Interventions for treating fractures of the patella in adults
Abstract
Background
Fractures of the patella (kneecap) account for around 1% of all human fractures. The treatment of these fractures can be surgical or conservative (such as immobilisation with a cast or brace). There are many different surgical and conservative interventions for treating fractures of the patella in adults.
Objectives
To assess the effects (benefits and harms) of interventions (surgical and conservative) for treating fractures of the patella in adults.
Search methods
We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register (2 May 2014), the Cochrane Central Register of Controlled Trials (The Cochrane Library, 2014, Issue 4), MEDLINE (1946 to April Week 4 2014), Ovid MEDLINE In‐Process & Other Non‐Indexed Citations (2 May 2014), Embase (1980 to 2014 Week 17), LILACS (1982 to 2 May 2014), trial registers and references lists of articles.
Selection criteria
Randomised controlled trials (RCTs) or quasi‐RCTs that evaluated any surgical or conservative intervention for treating adults with fractures of the patella were eligible for inclusion. The primary outcomes were patient‐rated knee function and knee pain, and major adverse outcomes.
Data collection and analysis
At least two review authors independently selected eligible trials, assessed risk of bias and cross‐checked data extraction. Where appropriate, results of comparable trials were pooled.
Main results
We included five small trials involving 169 participants with patella fractures. Participant age ranged from 16 to 76 years. There were 68 females and 100 males; the gender of one participant was not reported. Two trials were conducted in China and one each in Finland, Mexico and Turkey.
All five trials compared different surgical interventions. Two trials compared biodegradable versus metallic implants for treating displaced patella fractures; one trial compared patellectomy with advancement of vastus medialis obliquus versus simple patellectomy for treating comminuted patella fractures; and two trials compared percutaneous osteosynthesis (both procedures were 'novel' and one used a new device) versus open surgery for treating displaced patella fractures. All the trials had design flaws, such as lack of assessor blinding, which put them at high risk of bias, potentially limiting the reliability of their findings. No trial reported on health‐related quality of life, return to previous activity or cosmetic appearance.
Very low quality evidence from two trials (48 participants) comparing biodegradable versus metallic implants indicated little difference between the two interventions at two‐year follow‐up in the numbers of participants with occasional knee pain (1/23 versus 2/24), incurring adverse events (3/24 versus 1/24) or with reduced knee motion (2/23 versus 2/24). Neither trial reported patient‐rated knee function scores. In one trial, as per routine practice, metallic implants were removed one year after surgery (four participants). The other trial did not report on this aspect.
Very low quality evidence from one trial (28 participants) indicated that compared with simple patellectomy, patellectomy with advancement of vastus medialis obliquus surgery for treating comminuted patella fractures resulted in more participants with a 'good' result based on a subjectively rated score (12/12 versus 11/16; risk ratio (RR) 1.42, 95% confidence interval (CI) 1.01 to 2.01), fewer participants experiencing knee pain (5/12 versus 13/16; RR 3.11, 95% CI 1.01 to 9.60) and more participants with unlimited activity and no loss in quadriceps strength at four‐year follow‐up. The only adverse event reported was a patellar tendon subluxation in the simple patellectomy group.
Neither trial comparing percutaneous osteosynthesis (using novel devices or methods) versus open surgery reported on patient‐rated knee function scores. Very low quality evidence from two trials (93 participants) showed that percutaneous osteosynthesis improved knee pain measured using visual analogue scale (0 to 10 where 10 is worst pain) at one month (mean difference (MD) ‐2.24, 95% CI ‐2.80 to ‐1.68) and at up to three months (MD ‐1.87, 95% CI ‐2.45 to ‐1.29). This effect did not persist at six months (very low quality evidence from one trial). Very low quality evidence from the two trials showed significantly fewer participants with adverse events (loss of reduction, infection, hardware complications, delayed wound healing) after percutaneous surgery (8/47 versus 28/46; RR 0.28, 95% CI 0.14 to 0.55). Very low quality evidence from the two trials indicated better clinician‐rated knee function scores after percutaneous fixation at two to three months and 12 months follow‐up; however, the between‐group difference was not clinically important at 24 months. Very low quality evidence showed a lower incidence of hardware removal in the percutaneous group at two years; however, the results in the two trials were heterogeneous and the reasons for removal were not given in detail.
Authors' conclusions
There is very limited evidence from RCTs about the relative effects of different surgical interventions for treating fractures of the patella in adults. There is no evidence from RCTs evaluating the relative effects of surgical versus conservative treatment or different types of conservative interventions.
Based on very low quality evidence, biodegradable implants seem to be no better than metallic implants for displaced patellar fractures; patellectomy with vastus medialis obliquus advancement may give better results than simple patellectomy for comminuted patellar fractures; and two novel methods of percutaneous osteosynthesis may give better results than conventional open surgery. However, until conclusive evidence becomes available, treatment options must be chosen on an individual patient basis, carefully considering the relative benefits and harms of each intervention and patient preferences. Further randomised trials are needed, but in order to optimise research effort, these should be preceded by research that aims to identify priority questions.
PICOs
Plain language summary
Treatments for broken kneecaps in adults
Broken kneecaps (patella fractures) account for 1% of all fractures. There are many treatments for these fractures and they can be treated with surgery or conservatively (any treatment where surgery is not used). Conservative interventions can be cast immobilisation, brace, immobilisation by traction and others. Surgery can be open or percutaneous (through a needle), can use metallic or non‐metallic implants, and the implants can be wires, screws or plates.
Aim of review
This review aimed to evaluate the effects of different methods for treating kneecap fractures in adults, with or without surgery. The main outcomes we were interested in were patient‐rated knee function, pain and complications.
Search results and quality of the evidence
We searched the scientific literature up to May 2014 and found five relevant studies with a total of 169 participants. Participants in these studies were aged between 16 and 76 years. There were 68 females and 100 males; the gender of one participant was not reported. Two studies were conducted in China, and one each in Finland, Mexico and Turkey. All five studies compared different types of surgery or surgical devices. Thus, we found no studies comparing different types of conservative treatment or surgery versus conservative treatment.
The five studies made three comparisons. We judged the evidence available for each comparison was of very low quality. This was because all the trials had design flaws that put them at high risk of bias and the studies were also too small.
What the included studies found
None of the studies reported on health‐related quality of life, return to previous activity or cosmetic appearance.
Two studies comparing biodegradable (non‐metallic) versus metallic implants found little difference in outcomes (knee pain, adverse events and function) between the two groups. Neither study reported on patient‐rated function.
One study compared patellectomy with repositioning of a tendon with simple patellectomy (kneecap is removed) for treating complex kneecap fractures. It found that tendon repositioning resulted in more participants reporting better knee function and fewer participants with pain and limited knee function. One participant had an adverse event.
Two studies found that novel methods of percutaneous fixation (surgery using small incisions to insert the fixation devices) resulted in less knee pain and fewer adverse events (mainly relating to the fracture fixation materials) than open surgery (involving wide incisions). Neither study reported on patient‐rated function.
Conclusions
Overall, the evidence is very low quality and is insufficient to draw firm conclusions about the best method of treatment for kneecap fractures. Treatment options must be chosen on an individual patient basis, carefully considering the relative benefits and harms of each intervention and patient preferences. Further research is warranted and should be preceded by research to determine which questions should be prioritised.
Authors' conclusions
Background
The patella has several important functions. It acts as protective shield for the knee joint, augments the strength of the quadriceps muscle and has a cosmetic function. These functions can be damaged by the occurrence of fractures.
Description of the condition
The patella or kneecap is one of the three bones that form the knee joint. It is the largest sesamoid bone (i.e. bone embedded within a tendon; in this case, the patellar tendon) in the human body and has a rounded triangular shape. The cartilage‐covered underside of the patella articulates with the two lower ends (condyles) of the femur (the thigh bone). The patella acts as a protective shield for the knee joint, augments the effect of the quadriceps muscle during knee extension (straightening) and has a cosmetic function (Anderson 1978; Insall 2006).
Fractures of the patella account for approximately 1% of all skeletal fractures (Us 1966; Weber 1980), with an overall incidence of 10.7 per 100,000 people per year (Court‐Brown 2006). These fractures occur mainly in people aged between 20 and 50 years and around twice as often in men than women. Only two to seven per cent of fractures of the patella are open (Dy 2012; Insall 2006; Muller 1991). Common causes of patellar fractures are falls onto the knee, blows and sudden severe muscle pulls (Muller 1991).
Typically, the diagnosis of patellar fracture is made from the patient's history, physical examination and plain radiography. Magnetic resonance imaging or computed tomography are generally required only for more subtle injuries (Helfet 2003). The physical signs of a patellar fracture are deformity, inability to extend the knee, tenderness, and in some cases, a palpable gap. Most fractures are transverse (horizontally across the patella). Complications include haemorrhage (bleeding) into the knee joint and serious tears of the surrounding soft tissues of the joint (Catalano 1995; Levack 1985).
The classifications for describing these fractures are based on mechanism of injury, the degree of displacement, the fracture pattern or a combination of two or more of these descriptors. A commonly used classification based on fracture pattern includes the following descriptors: transverse, vertical, stellate (comminuted, i.e. broken into several pieces), apical, marginal and osteochondral (Insall 2006; Sturdee 2002). The fracture pattern often influences the choice of treatment.
Description of the intervention
Fractures of the patella can be treated conservatively or surgically (Insall 2006; Lotke 1981). Treatment approaches are often based on practitioner preferences and patient characteristics. Surgery should be avoided in patients with high preoperative risk or in those with joint ankylosis, prior failed extensor mechanism or those who are non‐ambulatory (Melvin 2011).
Conservative intervention involves immobilisation of the leg in nearly full extension for five to six weeks through the use of a long‐leg plaster or other type of cast or a brace. The patient is often allowed to partially weight‐bear during this time and most people will use crutches to get about. The leg is kept straight until fracture consolidation (healing) is evident on radiographs (Torchia 1996). Typically, conservative treatment is used for people with less severe fractures, such as non‐displaced (still in place) fractures.
Surgical treatment generally entails reducing (realigning) the displaced fragments and fixing these together with some combination of screws, pins and wires. One fixation method developed in the 1950s by the Arbeitssgemeinschaft fur Osteosynthesefragen/Association for the Study of Internal Fixation (AO/ASIF) is the anterior tension band principle, which offers a stable construct for some fracture types (e.g. transverse fractures), allowing early mobilisation (Günal 1997; Helfet 2003). Two other surgical techniques used since the 1960s are partial and complete patellectomy (Appel 1993; Insall 2006). These entail the partial or total removal of the patella. Typically, surgical intervention is considered for fractures that have greater than 2 mm of articular displacement or 3 mm of fragment separation, in comminuted fractures with displacement of the articular surface, in osteochondral fractures with displacement into the joint, in marginal or longitudinal fractures with comminution or displacement, and in any case in which the integrity of the extensor mechanism has been lost. The objectives of surgical treatment are to obtain accurate reduction of the fracture and the joint surface, provide stable fixation to allow early range of motion and restore the knee‐extensor mechanism.
Surgery can be percutaneous (via a needle) or conventional (open). There are many options for skin incisions and methods of internal fixation. Skin incisions can be transversal, longitudinal, medial longitudinal and lateral longitudinal. Techniques described for internal fixation include tension band wiring and screw fixation. The material used for fixation may be metallic or biodegradable (Melvin 2011).
How the intervention might work
Conservative intervention is usually chosen when there is integrity of the extensor mechanism (the leg can be straightened out), good preservation of articular congruity (joint surfaces fit correctly together) and lack of displacement between bone fragments. Where these conditions are not met, surgical intervention for patellar fracture has been advocated as hypothetically, it enables the restoration of the joint anatomy, thus avoiding deformity, incongruity and an unsatisfactory outcome. However, key disadvantages of surgery include potential migration and breakage of wires and pins, erosion of the bone, failure of the fixation methods, loss of reduction, a painful or unsightly scar, development of arthralgia and arthritis or need of a second surgery to remove the fixation hardware (Helfet 2003; Smith 1997).
The advantages of the conservative interventions are avoidance of hospitalisation, surgery and anaesthesia. The disadvantages are a longer period of immobilisation, possible loss of reduction and possible stiffness resulting from fibrous adhesions in the joint (Muller 1991).
Fracture fixation may be achieved in various ways. Several implants are available and the choice should be directed by the fracture pattern. The most common method is a tension band technique; however, this is only possible after the fracture is converted into a two‐part fracture. Additional fracture fragments can be fixed using supplementary small fragments or mini‐fragment screws (Baran 2009; Berg 1997; Fortis 2002).
In addition, evaluation of the extent of comminution is crucial; infrequently, a partial or total patellectomy should be performed, such as in cases of severe and irreparable comminution. The patient should be informed of the possible need for fragment excision, which might cause loss of strength of the extensor mechanism (Donken 2009; Günal 2001; LeBrun 2012).
Why it is important to do this review
As outlined above, there are many surgical or conservative interventions for treating patella fractures in adults, each having advantages and disadvantages. Although the undisplaced acute fractures used to be treated conservatively, the current treatment of some types of patellar fracture is more invasive, involving surgery. There is limited evidence to guide the clinical practice on management of patellar fractures and available systematic reviews do not restrict their included studies to randomised controlled trials (Dy 2012; Heusinkveld 2013a).
Objectives
To assess the effects (benefits and harms) of interventions (surgical and conservative) for treating fractures of the patella in adults.
Methods
Criteria for considering studies for this review
Types of studies
Randomised controlled trials (RCTs) that evaluated interventions (surgical and conservative) for treating fractures of the patella in adults were included. Quasi‐RCTs (method of allocating participants to a treatment that is not strictly random, e.g. by date of birth, hospital record number, alternation) were also eligible for inclusion.
Types of participants
Trials with adult participants with one (unilateral) or two (bilateral) acute patella fractures were included. We included trials with other knee injuries if separate data for participants with an acute patella fracture were available.
Types of interventions
All surgical and conservative interventions used for treating patella fractures were considered.
Surgical interventions could include internal fixation using anterior tension band, screw fixation, wires in cerclage and partial or total patellectomy. Conservative interventions could include cast, plaster cast and brace. The broad comparisons of interest were: different types of conservative interventions; surgical versus conservative interventions; and different types of surgical interventions.
Types of outcome measures
Primary outcomes
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Patient‐rated, preferably validated, knee function scores (for example, Knee Injury and Osteoarthritis Outcome Score (KOOS) (Roos 1998), Lysholm Knee Questionnaire (Lysholm 1982) and Tegner Activity Scale (Tegner 1985)). A specific scoring scheme for patellofemoral disorders is the Kujala score (Kujala 1993)
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Anterior knee pain. Preference was given to reports of pain measured using validated pain scales, such as visual analogue scale (VAS) and numeric rating scale (NRS)
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Major adverse outcomes (for example, infection, venous thromboembolism) as well as treatment failure requiring secondary unplanned intervention (for example, operation or re‐operation for unresolved non‐union or loss of reduction; problems with internal fixation devices)
Timing of primary outcome measurement
We extracted outcome data at the following time periods: short term (up to six weeks following treatment); intermediate term (more than six weeks and up to six months after the end of treatment) and long term (greater than six months after the end of treatment).
Secondary outcomes
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Observer‐rated measures of knee function (for example, knee range of motion, knee strength) including those measured with clinician‐rated knee scoring systems (for example, Knee Society Clinical Rating System (Insall 1989))
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Health‐related quality of life scores (for example, Short‐form 36 (SF‐36) (Ware 1992))
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Return to previous activities (sports, manual labour, etc) (including time to return)
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Cosmetic appearance including deformity
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Hardware removal
Search methods for identification of studies
Electronic searches
We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register (2 May 2014), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, 2014, Issue 4), MEDLINE (1946 to April Week 4 2014), Ovid MEDLINE In‐Process & Other Non‐Indexed Citations (2 May 2014), Embase (1980 to 2014 Week 17) and LILACS ‐ Latin American and Caribbean Health Sciences Literature (1982 to 2 May 2014). We searched the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP) and the ClinicalTrials.gov registry to May 2014 for ongoing and recently completed studies. We did not apply any restrictions based on language or publication status.
In MEDLINE, a subject‐specific strategy was combined with the sensitivity‐maximising version of the Cochrane Highly Sensitive Search Strategy for identifying randomised trials: (Lefebvre 2011) (seeAppendix 1). Search strategies for the Cochrane Central Register of Controlled Trials, EMBASE and LILACS are also shown in Appendix 1.
Searching other resources
We searched reference lists from relevant articles, reviews and textbooks for possible studies, and contacted experts in the field.
Data collection and analysis
Selection of studies
Two review authors (JS and RT) selected and assessed potentially eligible studies for inclusion in the review using a pre‐piloted form. We resolved any disagreements by discussion and, if necessary, adjudication by a third author (ML).
Data extraction and management
Two review authors (JS and RT) used a pre‐piloted data extraction form to independently collect data including methods, participants, interventions and outcomes. Any disagreements were resolved by a third review author (ML). Two review authors (JS and ML) entered data into Review Manager software. We sent requests to trial authors for additional information or data.
Assessment of risk of bias in included studies
Two review authors (JS and ML) independently assessed the included trials for risk of bias using the domain‐based evaluation described in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). We assessed the following domains.
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Random sequence generation
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Allocation concealment
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Blinding of participants and personnel
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Blinding of outcome assessment
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Incomplete outcome data
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Selective reporting
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Other bias (for example, major baseline imbalance; inappropriate influence of funders; and risk of bias associated with inexperience of surgeons and other care providers with the interventions, and differences in rehabilitation)
Each of these criteria was explicitly judged as low risk of bias, high risk of bias or unclear risk of bias (either lack of information or uncertainty over the potential for bias). Disagreements between review authors regarding the risk of bias for domains were resolved by consensus.
Measures of treatment effect
We calculated risk ratios (RRs) together with 95% confidence intervals (CIs) for dichotomous outcomes. Continuous outcome data were expressed as mean differences (MDs) with 95% CIs. The standardised mean difference (SMD) was used where different scales were used to measure the same continuous outcome. When appropriate, we intended to report the number needed to treat to benefit (NNTB) and the number needed to treat to harm (NNTH), both with 95% CIs.
Unit of analysis issues
The unit of randomisation for the included trials was the individual participant. We were alert to potential unit of analysis issues such as those relating to reporting of outcomes at different times or where participants had multiple complications. In the Effects of interventions section, we have highlighted the one instance where we may have inadvertently presented data from one trial for total complications rather than total number of participants with complications, but we suggest that the problem is unlikely to have serious implications in this case.
Dealing with missing data
We performed an intention‐to treat analysis to include all participants randomised to any intervention. When there was insufficient information relevant to estimate effects, such as number of participants, means, measures of uncertainty (standard deviation or error), or number of events and participants, we contacted the main authors of the included trials.
Where it was impossible to acquire adequate data for a forest plot (for example, means and standard deviations), we present data in the text.
Assessment of heterogeneity
We assessed the heterogeneity of estimate effects between the included studies by visual inspection of the forest plot (analysis) along with consideration of the Chi² test for heterogeneity and the I² statistic.
We quantified the possible magnitude of inconsistency (i.e. heterogeneity) through studies, using the I² statistic as follows: 0% to 40% might not be important; 30% to 60% may represent moderate heterogeneity; 50% to 90% may represent substantial heterogeneity; and 75% to 100%, very substantial ("considerable") heterogeneity (Deeks 2008). In cases of considerable heterogeneity (defined as I² ≥ 75%), we explored the data further by comparing the characteristics of individual studies and conducting subgroup analyses.
Assessment of reporting biases
We had planned to draw funnel plots of primary outcomes to assess the potential publication bias; however, the small number of included trials precluded this form of analysis.
We assessed the presence of small‐study bias in the overall meta‐analysis by checking whether the random‐effects estimate of the intervention effect showed more benefit than the fixed‐effect estimate. We also assessed outcome reporting bias by comparing results extracted from published journal reports with results from other sources (e.g. correspondence) and by checking trial registrations (at the WHO International Clinical Trials Registry Platform) or published protocols.
Data synthesis
When considered appropriate, we pooled results of comparable groups of trials using the fixed‐effect model and 95% CIs. We also checked the results using the random‐effects model where there was diversity in clinical or methodological characteristics, and presented random‐effects results where there was significant heterogeneity.
Subgroup analysis and investigation of heterogeneity
There were insufficient data to perform the planned subgroup analyses by age (people older than 65 years compared with those under 65), type of fracture (transverse versus comminuted) or timing of surgery (immediate versus delayed (from one week to four weeks after injury)). In future updates, should these analyses be possible, we will test whether subgroups were statistically significantly different from one another using the test for interaction provided in Review Manager.
Sensitivity analysis
There were insufficient data to conduct the planned sensitivity analyses examining various aspects of trial and review methodology, including the effects of missing data and study risk of bias relating to inadequate allocation concealment and lack of outcome assessor blinding.
'Summary of findings' tables and assessment of the quality of the evidence
We used the GRADE approach to assess the quality of evidence related to each of the key outcomes listed in Types of outcome measures (Schunemann 2011, Section 12.2). Where there is sufficient evidence in future to merit the preparation of 'Summary of findings' tables, we will develop these for the main comparisons.
Results
Description of studies
See Characteristics of included studies and Characteristics of excluded studies.
Results of the search
The search was completed in May 2014. We screened a total of 376 records from the following databases: Cochrane Bone, Joint and Muscle Trauma Group Specialised Register (9 records), CENTRAL (33), MEDLINE (101), EMBASE (169), LILACS (56), ClinicalTrials.gov (7) and the WHO ICTRP (1). We did not identify any potentially eligible studies from searching reference lists of relevant articles.
The search identified citations for 14 reports of potentially eligible studies, for which full reports were obtained. We included a total of five studies (Chen 1998; Günal 1997; Juutilainen 1995; Luna‐Pizarro 2006; Mao 2013). No trial was preceded by trial registration.
Overall, there are five included studies, nine excluded studies (Chang 2011; Gosal 2001; Heusinkveld 2013b; Hoshino 2013; Lee 2014; Luna Pizarro 2008; Mao 2012; Tang 2013; Xu 2013), no ongoing trials and no studies awaiting classification (Figure 1).
Study flow diagram
Included studies
Details of the five studies can be found in the Characteristics of included studies. Each trial reported their results in a single publication and all trials are reported in English.
Design and setting
All studies were single‐centre parallel randomised controlled trials with two interventions groups. Chen 1998 and Mao 2013 took place in China, Juutilainen 1995 in Finland, Luna‐Pizarro 2006 in Mexico and Günal 1997 in Turkey.
Sample sizes
The five trials enrolled a total of 169 participants; outcome data allowing analysis by the trial authors were available for a maximum of 159 participants (94.1%).
Participants
Age and gender
All the included participants were adults; their ages ranged between 16 and 76 years. The 38 participants (11 female and 27 male) in Chen 1998 were aged between 20 years and 76 years (mean age 46 years). Günal 1997 stipulated that all 28 participants (12 female and 16 male) were skeletally mature (mean age was 28 years). Juutilainen 1995 included 10 participants (seven female and two male; gender of the excluded participant not reported) aged between 29 to 69 years (mean age was 48 years). Luna‐Pizarro 2006 included 53 participants (23 female and 30 male) aged between 16 to 74 years (mean age was 47 years). Mao 2013 included 40 participants (15 female and 25 male) between 22 to 65 years (mean age was 42 years).
Thus, overall, 59% of the 169 randomised participants were male. Juutilainen 1995 reported the lowest percentages of males (22%) and Chen 1998, the highest percentages of males (71%).
Type/Classification of fractures
Chen 1998 and Juutilainen 1995 included participants with transverse or oblique displaced fractures; Günal 1997 included only comminuted fractures; and Mao 2013 included participants with transverse displaced fractures. Only Luna‐Pizarro 2006 used the AO classification (Muller 1991); but also described complete articular transverse fractures. Patients with open fractures were explicitly excluded from four trials, and also not reported in Günal 1997.
Interventions
All five trials compared different surgical interventions. We grouped the included trials into three comparisons.
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Biodegradable (biotension band wiring plus screws or plugs made of biomaterials that are degradable) versus metallic implants (tension band wiring) (Chen 1998; Juutilainen 1995). Follow‐up data were available for 47 participants (23 with biodegradable implant and 24 with metallic implant).
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Patellectomy with advancement of vastus medialis obliquus versus simple patellectomy (Günal 1997). Follow‐up data were available for 28 participants (12 with patellectomy with advancement of vastus medialis obliquus versus 16 with simple patellectomy).
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Percutaneous patellar osteosynthesis (minimally invasive surgery that uses small incisions and devices or implants as tension band, screws and others) versus open surgery (traditional surgery that uses wide incisions and traditional devices or implants as tension band, screws, wires and others) (Luna‐Pizarro 2006; Mao 2013). Luna‐Pizarro 2006 compared the percutaneous patellar osteosynthesis system (a new device to use the tension band technique in a percutaneous way) versus open surgery involving the tension band technique. Mao 2013 compared the cable pin system (a combination of interfragmentary screws and the tension band wire percutaneously) versus open surgery involving the tension band technique. Follow‐up data were available for 84 participants (43 with percutaneous patellar osteosynthesis and 41 with open surgery).
Outcomes
Primary outcomes
Patient‐rated knee function scores
Only one trial (Günal 1997) measured patient‐rated knee function; however, this was part of a non‐validated score described by Levack 1985.
Anterior knee pain
All of the included studies assessed knee pain. Chen 1998 graded pain in three categories: no more than slight or occasional pain, occasional to moderate pain, constant pain. Günal 1997 graded pain as: no pain, minimal pain during activity, constant severe pain. Juutilainen 1995 graded pain as: no pain or pain. Luna‐Pizarro 2006 and Mao 2013 measured pain by a VAS (from 0 (no pain) to 10 (most intense pain)).
Major adverse outcomes
All of the included studies reported on major adverse outcomes. Chen 1998 reported on infection, redisplacement, delayed wound healing and complications of bioabsorbable implants. Günal 1997 reported on heterotopic ossification, lateral subluxation of patellar tendon and quadriceps tendon rupture. Juutilainen 1995 reported on infection, radiographic loss of reduction, refracture and complications of bioabsorbable implants. Luna‐Pizarro 2006 reported on infection, painful hardware and redisplacement. Mao 2013 assessed loss of reduction, migration hardware and broken wires.
Secondary outcomes
Observer‐rated measures of knee function
Using a non‐validated score, Chen 1998 evaluated loss of movement in three categories: loss of movement of less than 15 degrees at the knee, loss of movement of 15 to 30 degrees at the knee and loss of more than 30 degrees at the knee. Günal 1997 assessed limitation of activity, loss of quadriceps strength and functional assessment using a non‐validated score described by Marshall 1977 (a functional assessment scale used for recovery after knee ligament injuries, where patients are asked to duck‐walk, run on the spot, jump on one leg and squat). Juutilainen 1995 reported loss of movement in two categories: normal or restricted range of movement of the knee. Luna‐Pizarro 2006 reported the outcome by goniometry for flexion and extension and used the Knee Society Clinical Rating System. Mao 2013 assessed knee range of motion and Bostman score (Böstman 1981).
Health‐related quality of life scores
None of the included trials evaluated health‐related quality of life scores.
Return to previous activity
None of the included trials evaluated return or time to return to previous activities.
Cosmetic appearance
None of the included trials evaluated cosmetic appearance.
Hardware removal
Removal of hardware, either routine or for symptoms, was reported in three trials (Juutilainen 1995; Luna‐Pizarro 2006; Mao 2013).
Other outcomes
Four trials evaluated other outcomes that are not included in this review. Chen 1998 evaluated time to union and radiographic results (graded as poor, fair or good) and wound healing. Juutilainen 1995 evaluated radiographic results (graded as poor or good). Luna‐Pizarro 2006 evaluated surgical time and Mao 2013 evaluated wound healing, operating time and use of intraoperative fluoroscopy.
Timing of outcome measurements
The studies varied in the timing of follow‐up. Although Chen 1998 evaluated outcome at three and eight weeks and three, six and 12 months after the surgery, as well as a final follow‐up at 24 months on average (range 14 to 32 months), they only reported results at the final follow‐up (long‐term follow‐up). Günal 1997 reported that the time of the measurements was at least three years after surgery (mean 4.2 years). Juutilainen 1995 evaluated the outcomes at two, four and six weeks, three and six months, one and two years; however, they only reported results at final follow‐up (long‐term follow‐up). Luna‐Pizarro 2006 evaluated at four and eight weeks and at 12 and 24 months. Participants were evaluated at one, three, six, 12, and 24 months after surgery in Mao 2013. For the two studies that reported multiple time points (Luna‐Pizarro 2006; Mao 2013), we considered short‐term follow‐up: four weeks in Luna‐Pizarro 2006 and one month in Mao 2013; intermediate follow‐up: eight weeks in Luna‐Pizarro 2006 and three months in Mao 2013, we also considered six months as intermediate follow‐up only for the outcome VAS score for pain in Mao 2013; and long‐term follow‐up 12 and 24 months in different analysis in both trials (Luna‐Pizarro 2006; Mao 2013).
Excluded studies
We excluded nine studies because they were not RCTs; see Characteristics of excluded studies.
Risk of bias in included studies
All trials had methodological flaws rendering them at high risk of bias (see Figure 2 and Figure 3)
'Risk of bias' graph: review authors' judgements about each risk of bias item presented as percentages across all included studies
'Risk of bias' summary: review authors' judgements about each risk of bias item for each included study
Allocation
Three studies (Chen 1998; Juutilainen 1995; Luna‐Pizarro 2006) were judged as unclear in terms of risk of bias because they provided insufficient information about the sequence generation process to permit a judgement about bias. Günal 1997 and Mao 2013 were at low risk of bias: Günal 1997 reported that random sequence generation was performed by drawing lots and Mao 2013 reported that random sequence generation was performed using a computer random number generator.
Since Chen 1998, Günal 1997 and Juutilainen 1995 did not describe their methods of allocation concealment, we assessed them as unclear risk of bias. Both Luna‐Pizarro 2006 and Mao 2013 used sealed envelopes but the former, which we judged as unclear risk of bias, provided no other details of safeguards. We judged Mao 2013 to be at low risk of bias because the sealed envelopes were also sequentially numbered and opaque.
Blinding
We judged all trials to be at high risk of performance and detection bias. As the trials all compared surgical interventions, it was not possible to blind treatment providers. No trials included sham surgery or blinded the participants. While it may have been possible to blind outcome assessors, none of the trials mentioned assessor blinding.
Incomplete outcome data
We considered trials to be at low risk of bias if more than 80% of participants completed the follow‐up, missing outcomes data were balanced in number across intervention groups and an intention‐to‐treat analysis was reported for the primary outcomes. As all of the studies met these criteria, we judged them to be at low risk of attrition bias. No participants were lost to follow‐up in Chen 1998 and Günal 1997. Juutilainen 1995 and Mao 2013 reported that only one participant was lost to follow‐up. Luna‐Pizarro 2006 reported that missing outcome data were balanced in numbers across intervention groups, with similar reasons for missing data across groups (8/53: 15% of participants were missing from follow‐up at 24 months).
Selective reporting
All of the included trials were considered to be at high risk of reporting bias because one or more outcomes of interest were incompletely reported or not reported; in addition, none of them provided details of their protocol or had prospective trial registration. In Chen 1998 and Juutilainen 1995, patient‐rated knee function and health‐related quality of life scores were not assessed, and anterior knee pain and observer‐rated measures of knee function were indirectly assessed using non‐validated scores. In Günal 1997, patient‐rated knee function scores and observer‐rated measures of knee function were measured by a non‐validated score, anterior knee pain was assessed only by a dichotomous endpoint and health‐related quality of life scores were not assessed. In Luna‐Pizarro 2006 and Mao 2013 patient‐rated knee function and health‐related quality of life scores were not assessed.
Other potential sources of bias
We judged that three trials (Chen 1998; Günal 1997; Juutilainen 1995) were at unclear risk of 'other' bias. The authors from Chen 1998 and Juutilainen 1995 did not provide sufficient information about the surgeons and care providers nor sufficient details of rehabilitation after surgery. Günal 1997 reported only the baseline characteristics of age and gender. We judged Luna‐Pizarro 2006 and Mao 2013 as being at high risk of other bias because of a potential conflict of interest reflecting the lack of independent scrutiny as each trial tested novel self‐developed techniques; in Luna‐Pizarro 2006, this also involved a locally designed device.
Effects of interventions
The included studies only compared different methods of surgical intervention. The three comparisons (biodegradable versus metallic implants; patellectomy with advancement of vastus medialis obliquus versus simple patellectomy; percutaneous patellar osteosynthesis versus open surgery) are described in turn.
Biodegradable versus metallic implants
Two trials, which recruited a total of 48 participants, compared biodegradable implants for treating patella fractures with metallic tension bands (Chen 1998; Juutilainen 1995).
Patient‐rated knee function scores
This outcome was not measured by either trial.
Anterior knee pain
Both trials assessed pain. Pooled data showed little difference between the two groups at long‐term follow‐up in participants with pain (1/23 versus 2/24; risk ratio (RR) 0.56 favouring biodegradable implants, 95% confidence interval (CI) 0.05 to 5.62; Analysis 1.1). All three participants with pain in Chen 1998 had 'occasional pain'. No participants in Juutilainen 1995 reported pain at long‐term follow‐up.
Major adverse outcomes
The sole case of 'treatment failure' was a refracture after new trauma in the biodegradable group in Juutilainen 1995. Other adverse outcomes were an infection in the metallic group of Chen 1998 and two cases of delayed wound healing in the biodegradable group, also in Chen 1998. Neither trial found evidence of complications of biodegradable implants (aseptic swelling or sinus tract formation), although Chen 1998 observed that tissue reaction may have contributed to delayed wound healing. Overall, there was no evidence confirming a difference between groups in the pooled results for adverse events from the two trials (Chen 1998; Juutilainen 1995) (3/24 versus 1/24; RR 2.19 favouring metallic implants, 95% CI 0.35 to 13.66; Analysis 1.2).
Observer‐rated measures of knee function
Both trials assessed range of knee motion. Pooled data showed similar numbers in the two groups had reduced knee motion at long‐term follow‐up (2/23 versus 2/24; RR 1.11, 95% CI 0.17 to 7.09; Analysis 1.3). All four participants in Chen 1998 had loss of knee motion of 20 degrees or more. All participants in Juutilainen 1995 were reported to have regained a good range of motion at long‐term follow‐up.
Health‐related quality of life scores
Neither trial measured any health‐related quality of life score.
Return to previous activity
Return or time to return to previous activity outcomes were not measured by either trial.
Cosmetic appearance including deformity
Cosmetic appearance outcomes were not measured by either trial.
Hardware removal
Juutilainen 1995 reported that all metallic implants were removed one year after the primary operation.
Patellectomy with advancement of vastus medialis obliquus versus simple patellectomy
One trial with 28 participants compared patellectomy with vastus medialis obliquus (VMO) advancement versus simple patellectomy for treating comminuted fractures of the patella (Günal 1997). Both interventions entailed open surgery.
Patient‐rated knee function scores
Günal 1997 reported subjective patient‐rated knee function rated using a part of the non‐validated Levack score (Levack 1985). They found all participants in the VMO advancement group had good results (scoring over 50 points or a 100 point score) at long‐term follow‐up compared with only 69% of those in the simple patellectomy group (12/12 versus 11/16; RR 1.42 favouring VMO advancement; 95% CI 1.01 to 2.01; Analysis 2.1).
Anterior knee pain
The difference in the number of participants with pain at long‐term follow‐up also favoured the VMO advancement group (5/12 versus 13/16; RR 3.11, 95% CI 1.01 to 9.60; Analysis 2.2).
Major adverse outcomes
There were no cases of heterotopic ossification and quadriceps rupture in either group. The only adverse event reported was a patellar tendon subluxation in the simple patellectomy group (0/12 versus 1/16; RR 0.44 favouring VMO advancement, 95% CI 0.02 to 9.85; Analysis 2.3).
Observer‐rated measures of knee function
Data from Günal 1997 found significantly better results in favour of the patellectomy with the vastus medialis obliquus advancement with respect to the number of participants who had unlimited activity (RR 4.44 favouring VMO advancement, 95% CI 1.55 to 12.71) and number of participants with no loss of quadriceps strength (RR 10.90 favouring VMO advancement, 95% CI 2.36 to 50.42; Analysis 2.4). In terms of specific activities, all participants in both groups could perform a 'duck‐walk' and squat fully. However, three participants in the simple patellectomy group could not run on the spot and four in the same group could not jump on one leg (see Analysis 2.4).
Health‐related quality of life scores
Günal 1997 did not measure any health‐related quality of life scores.
Return to previous activity
Günal 1997 did not assess return or time to return to previous activities.
Cosmetic appearance including deformity
Günal 1997 did not measure cosmetic appearance outcomes.
Percutaneous patellar osteosynthesis versus open surgery
Percutaneous patellar osteosynthesis for treating patella fractures was compared with open surgery in two trials, which recruited a total of 93 participants (Luna‐Pizarro 2006; Mao 2013).
Patient‐rated knee function scores
This outcome was not measured by either trial.
Anterior knee pain
Pooled data (VAS: 0 to 10: worse score) from the two trials (93 participants) demonstrated better short‐term and intermediate‐term pain outcomes in the percutaneous patellar osteosynthesis group (mean difference (MD) ‐2.24 percutaneous fixation, 95% CI ‐2.80 to ‐1.68; and MD ‐1.87 favouring percutaneous fixation, 95% CI ‐2.45 to ‐1.29, respectively; Analysis 3.1). Mao 2013 found no significant or clinically important difference between groups at six months follow‐up (MD ‐0.30, 95% CI ‐0.65 to 0.05; 40 participants) .
Major adverse outcomes
Luna‐Pizarro 2006 reported one case of intraoperative treatment failure in the percutaneous group where the patella fracture could not be reduced and a change in procedure was required. The results for postoperative adverse outcomes showed lower incidences of individual complications (loss of reduction, infection, hardware complications, delayed wound healing) in the percutaneous group (seeAnalysis 3.2). Pooled data from both trials showed a lower incidence of participants incurring an adverse event in the percutaneous group (8/47 versus 28/46; RR 0.28 favouring percutaneous fixation, 95% CI 0.14 to 0.55; Analysis 3.2). We cannot confirm that the data from Luna‐Pizarro 2006 apply to the total number of participants with complications rather than total complications where participants may have had more than one complication. However, individual patient data available for Mao 2013 show that of the 13 participants who had complications in the open surgery group, six participants had more than one complication: four participants had hardware migration plus hardware irritation, one participant had broken wires plus loss of reduction and one participant had hardware migration plus loss of reduction.
Observer‐rated measures of knee function
Two different observer‐rated measures of knee function (the Knee Society Clinical Rating System and Bostman score) were used in the two trials (Analysis 3.3). Pooled data using the standardised mean difference (SMD) showed better results for the percutaneous group at intermediate follow‐up (SMD 1.62 favouring percutaneous fixation, 95% CI 0.49 to 2.74; 93 participants), 12 months (SMD 1.31 favouring percutaneous fixation, 95% CI ‐0.07 to 2.69; 86 participants) and 24 months (SMD 0.62 favouring percutaneous fixation, 95% CI 0.18 to 1.06; 85 participants). However, the results at intermediate and 12 months follow‐up were significantly heterogeneous (P = 0.02, I2 = 82%; P = 0.004; I2 = 88%). The differences between groups in the actual effect sizes of both scales at 24 months were small and probably not clinically significant (Luna‐Pizarro 2006: 3.00, 95% CI 0.05 to 5.95; Mao 2013: 0.65, 95% CI 0.04 to 1.96); data not shown.
Knee range of motion
Pooled data for knee extension (Analysis 3.4) showed a small but clinically insignificant improvement in knee extension in favour of percutaneous patellar osteosynthesis at short‐term follow‐up (MD 1.68 degrees, 95% CI 0.74 to 2.62) and at intermediate‐term follow‐up (MD 2.10 degrees, 95% CI 1.27 to 2.93).
Pooled data for knee flexion (Analysis 3.5) showed a significant improvement in favour of percutaneous patellar osteosynthesis at short‐term follow‐up (MD 23.07 degrees, 95% CI 17.79 to 28.34) and at intermediate follow‐up (MD 33.29 degrees, 95% CI 25.80 to 40.78), but there was substantial heterogeneity at both follow‐ups (I2 = 90%; I2 = 94%, respectively). Long‐term follow‐up data for Mao 2013 also showed better results in favour of percutaneous patellar osteosynthesis at 12 months (MD 8.00 degrees, 95% CI 1.12 to 14.88) and at 24 months (MD 8.30 degrees, 95% CI 1.47 to 15.13); however, these are not clinically significant differences.
Health‐related quality of life scores
Neither trial measured any health‐related quality of life scores.
Return to previous activity
Return or time to return to previous activity outcomes were not measured by either trial.
Cosmetic appearance including deformity
Neither trial measured cosmetic appearance outcomes.
Hardware removal
Luna‐Pizarro 2006 reported on hardware removal due to pain or subcutaneous irritation at eight weeks and two years and Mao 2013 reported on hardware removal due to pain, irritation and psychological reasons at two years. Pooled data at two years showed a lower incidence of hardware removal in the percutaneous group (21/47 versus 33/46; RR 0.62, 95% CI 0.43 to 0.90) but the results were statistically heterogeneous (P = 0.008, I2 = 86%); see Analysis 3.6.
Discussion
Summary of main results
We found five small trials that assessed the effects (benefits and harms) of different surgical interventions for treating fractures of the patella in adults. These involved a total of 169 participants, aged between 16 and 76 years, with closed patella fractures. There were 68 females and 100 males, the gender of one participant was not reported. Two trials were conducted in China and one each in Finland, Mexico and Turkey.
Two trials (48 participants) compared biodegradable implants versus metallic implants for treating displaced patellar fractures; one trial (28 participants) compared patellectomy with advancement of vastus medialis obliquus versus simple patellectomy for patients with comminuted patellar fractures; and two trials (93 participants) compared percutaneous osteosynthesis versus open surgery for treating displaced patellar fractures. Overall, the quality of evidence was rated as very low for all outcomes reported for these comparisons.
Neither trial comparing biodegradable versus metallic implants reported on patient‐rated knee function scores, health‐related quality of life, return to previous activity or cosmetic appearance. Very low quality evidence (47 or 48 participants, two trials) indicated little difference between biodegradable versus metallic implants at two‐year follow‐up in the numbers of participants with knee pain, incurring adverse events or with reduced knee motion. As per routine practice in Juutilainen 1995, all metallic implants were removed at one year after surgery. Chen 1998 did not report on this aspect.
Very low quality evidence from one trial (Günal 1997) indicated that compared with simple patellectomy, patellectomy with advancement of vastus medialis obliquus surgery to treat comminuted patella fractures resulted in more participants with a 'good' result based on a subjectively rated score, fewer participants experiencing knee pain and more participants with unlimited activity and no loss in quadriceps strength. The only recorded adverse event was patellar tendon subluxation in the simple patellectomy group. The trial did not report on health‐related quality of life, return to previous activity or cosmetic appearance.
Neither trial (Luna‐Pizarro 2006; Mao 2013) comparing percutaneous osteosynthesis using novel devices or methods versus open surgery using the tension band technique reported on patient‐rated knee function scores, health‐related quality of life, return to previous activity or cosmetic appearance. Very low quality evidence from the two trials indicated less pain in the percutaneous group up to the first three months but the results from one trial showed no clinically important difference at six months. Very low quality evidence from two trials showed significantly fewer participants with adverse events (loss of reduction, infection, hardware complications, delayed wound healing) after percutaneous surgery (17%) than after open surgery (61%). (Both rates were notably higher than found for open surgery involving the tension band technique in the first comparison above (8.3% overall).) There was very low quality evidence from the two trials indicating better knee function scores after percutaneous fixation at two to three months, 12 and 24 months follow‐up. However, the between‐group difference was not clinically important at 24 months. Very low quality evidence showed a lower incidence of hardware removal in the percutaneous group at two years; however, the results in the two trials were heterogeneous and the reasons for removal were not given in detail.
Overall completeness and applicability of evidence
Only five randomised controlled trials providing follow‐up data for a total of 159 people with patella fractures are included in this review. These compared different surgical treatments for patella fractures; we did not find any trials comparing surgical versus conservative interventions or trials comparing different conservative interventions. Moreover, there was a maximum of two trials testing each of the three comparisons of different surgical treatments. None of these trials provided data for validated patient‐rated knee function, health‐related quality of life, return to previous activity outcomes or cosmetic appearance including deformity; all outcomes we consider important for these patients. We also received no response from the trial authors following our request for further details or data information for four of the five trials. Thus the data are very limited in quantity and are incomplete.
Despite the small numbers of trials and participants in each trial, we consider the gender and the age distribution are sufficiently representative. This also applies to the types of included fractures, the majority of which were transverse and all of which were closed. Only two to seven per cent of fractures of the patella are open (Dy 2012; Insall 2006; Muller 1991). The interventions applied in Günal 1997 were appropriate for the comminuted fractures included in this trial.
The surgical techniques tested in this review ranged from traditional techniques such as patellectomy and metallic tension band to new percutaneous techniques and devices, and biodegradable implants. As well as learning curve considerations relating to new techniques, it should be noted that the novel devices tested in Luna‐Pizarro 2006 and Mao 2013 are not generally available in current practice.
Quality of the evidence
Evidence was not available for many of the important outcomes for all three comparisons. Using the GRADE approach (Schunemann 2011), we assessed the evidence for each outcome reported for each comparison as very low quality. This means that we are very uncertain about the estimate of effect.
We downgraded the evidence by two levels because of risk of bias, reflecting that all five trials were at high risk of performance, detection and reporting biases (Figure 2). We downgraded a further level because of imprecision, reflecting the wide confidence intervals and the small sample sizes. For some outcomes, the quality of evidence was also reduced because of substantial heterogeneity (e.g. hardware removal at long‐term follow‐up for the percutaneous versus open surgery comparison). Downgrading for indirectness was also a consideration for the many poorly defined and poor quality outcome measures and also for the percutaneous versus open surgery comparison, where novel self‐developed techniques were used in the percutaneous surgery group. Thus the evidence is not robust for any of the three comparisons and we can affirm that the numerical results of this review should be interpreted with caution and viewed, at this stage, as requiring confirmation from future studies of good methodological quality and adequate power.
Potential biases in the review process
We conducted this review following criteria and methods set out in a published protocol (Sayum Filho 2012). We are confident that our search strategy was broad with no language restriction, and it has been maintained properly and regularly updated by the guarantor of review. We believe that the comprehensive literature search used in this review has found relevant studies and minimised the likelihood of missing trials; we also handsearched conference proceedings and searched for ongoing and recently completed trials. Nevertheless, it is possible that we have missed some potentially eligible trials. We tried to contact authors of all included trials to obtain further information and missing data from the included studies; however, this was unsuccessful.
Agreements and disagreements with other studies or reviews
We found two recently published non‐Cochrane systematic reviews that evaluated the surgical treatments for patellar fractures. Neither review restricted their results to randomised clinical trials (RCTs) only.
Dy 2012 aimed to assess the rates and factors that contribute to the following adverse events after open surgery: re‐operation, non‐union and infection. Dy 2012 included 24 studies (737 participants), only one of which was a RCT (Juutilainen 1995). Based on the included studies, the authors found that the frequency of re‐operation (because of treatment failure and hardware removal) was 33.6%, the rate of infection was 3.2% and the incidence of non‐union was 1.3%. In addition, they reported that there were no significant predictors for re‐operation, infection or non‐union in any of the regression analyses. We are uncertain of the validity of these results; however, we note as in our review, there was a large variation in the frequency of re‐operation.
Heusinkveld 2013a systematically assessed the effects of surgical interventions for treating patients with patella fractures. Their results, based on data from 20 studies (RCTs and non‐RCTs), included a total of 558 participants treated for a transverse patellar fracture. The authors concluded that the overall quality of the studies in this field was poor and reported that a direct comparison between fixation techniques using mixed or non‐metallic implants and metallic tension band fixation showed no significant difference in clinical outcome between both groups.
Our conclusions are consistent with Heusinkveld 2013a; though there are some important differences. For example, Heusinkveld 2013a considered Chen 1998 and Juutilainen 1995 to be prospective cohort studies, not RCTs. Next, we restricted our review to the results of RCTs only, extracted the data from the included trials following our pre‐established protocol and we did not use a scale to assess trial quality; such scales are not recommended because they provide unreliable assessments of validity (Juni 1999).
'Risk of bias' graph: review authors' judgements about each risk of bias item presented as percentages across all included studies
'Risk of bias' summary: review authors' judgements about each risk of bias item for each included study
Comparison 1 Biodegradable versus metallic implants, Outcome 1 Anterior knee pain at long‐term follow‐up (presence of pain).
Comparison 1 Biodegradable versus metallic implants, Outcome 2 Major adverse outcomes.
Comparison 1 Biodegradable versus metallic implants, Outcome 3 Observer‐rated measures of knee function.
Comparison 2 Patellectomy with vastus medialis obliquus (VMO) advancement versus simple patellectomy for comminuted fractures, Outcome 1 Patient‐rated knee function score.
Comparison 2 Patellectomy with vastus medialis obliquus (VMO) advancement versus simple patellectomy for comminuted fractures, Outcome 2 Anterior knee pain at long‐term follow‐up (presence of pain).
Comparison 2 Patellectomy with vastus medialis obliquus (VMO) advancement versus simple patellectomy for comminuted fractures, Outcome 3 Major adverse outcome.
Comparison 2 Patellectomy with vastus medialis obliquus (VMO) advancement versus simple patellectomy for comminuted fractures, Outcome 4 Observer‐rated measures of knee function at long‐term follow‐up.
Comparison 3 Percutaneous patellar osteosynthesis (PPO) versus open surgery, Outcome 1 Anterior knee pain (measured by VAS: 0 to 10 mm (worst score)).
Comparison 3 Percutaneous patellar osteosynthesis (PPO) versus open surgery, Outcome 2 Major adverse outcome.
Comparison 3 Percutaneous patellar osteosynthesis (PPO) versus open surgery, Outcome 3 Observer‐rated measures of knee function.
Comparison 3 Percutaneous patellar osteosynthesis (PPO) versus open surgery, Outcome 4 Knee range of motion: extension.
Comparison 3 Percutaneous patellar osteosynthesis (PPO) versus open surgery, Outcome 5 Knee range of motion: flexion.
Comparison 3 Percutaneous patellar osteosynthesis (PPO) versus open surgery, Outcome 6 Hardware removal (usually due to pain or subcutaneous irritation).
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Anterior knee pain at long‐term follow‐up (presence of pain) Show forest plot | 2 | 47 | Risk Ratio (M‐H, Fixed, 95% CI) | 0.56 [0.05, 5.62] |
| 2 Major adverse outcomes Show forest plot | 2 | Risk Ratio (M‐H, Fixed, 95% CI) | Subtotals only | |
| 2.1 Failure of treatment | 2 | 48 | Risk Ratio (M‐H, Fixed, 95% CI) | 2.14 [0.11, 42.52] |
| 2.2 Infection | 2 | 48 | Risk Ratio (M‐H, Fixed, 95% CI) | 0.37 [0.02, 8.51] |
| 2.3 Delayed wound healing | 2 | 48 | Risk Ratio (M‐H, Fixed, 95% CI) | 5.53 [0.28, 107.96] |
| 2.4 Total adverse events | 2 | 48 | Risk Ratio (M‐H, Fixed, 95% CI) | 2.19 [0.35, 13.66] |
| 3 Observer‐rated measures of knee function Show forest plot | 2 | Risk Ratio (M‐H, Fixed, 95% CI) | Subtotals only | |
| 3.1 Reduction in knee motion | 2 | 47 | Risk Ratio (M‐H, Fixed, 95% CI) | 1.11 [0.17, 7.09] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Patient‐rated knee function score Show forest plot | 1 | Risk Ratio (M‐H, Fixed, 95% CI) | Totals not selected | |
| 1.1 Levack score ‐ participants with good results at long‐term follow‐up | 1 | Risk Ratio (M‐H, Fixed, 95% CI) | 0.0 [0.0, 0.0] | |
| 2 Anterior knee pain at long‐term follow‐up (presence of pain) Show forest plot | 1 | Risk Ratio (M‐H, Fixed, 95% CI) | Totals not selected | |
| 3 Major adverse outcome Show forest plot | 1 | Risk Ratio (M‐H, Fixed, 95% CI) | Totals not selected | |
| 3.1 Patellar tendon subluxation | 1 | Risk Ratio (M‐H, Fixed, 95% CI) | 0.0 [0.0, 0.0] | |
| 3.2 Quadriceps rupture | 1 | Risk Ratio (M‐H, Fixed, 95% CI) | 0.0 [0.0, 0.0] | |
| 4 Observer‐rated measures of knee function at long‐term follow‐up Show forest plot | 1 | Risk Ratio (M‐H, Fixed, 95% CI) | Totals not selected | |
| 4.1 Number of participants with unlimited activity | 1 | Risk Ratio (M‐H, Fixed, 95% CI) | 0.0 [0.0, 0.0] | |
| 4.2 Number of participants with no loss of quadriceps strength | 1 | Risk Ratio (M‐H, Fixed, 95% CI) | 0.0 [0.0, 0.0] | |
| 4.3 Number of participants who could run on spot | 1 | Risk Ratio (M‐H, Fixed, 95% CI) | 0.0 [0.0, 0.0] | |
| 4.4 Number of participants who could jump on one leg | 1 | Risk Ratio (M‐H, Fixed, 95% CI) | 0.0 [0.0, 0.0] | |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Anterior knee pain (measured by VAS: 0 to 10 mm (worst score)) Show forest plot | 2 | Mean Difference (IV, Fixed, 95% CI) | Subtotals only | |
| 1.1 At short‐term follow‐up | 2 | 93 | Mean Difference (IV, Fixed, 95% CI) | ‐2.24 [‐2.80, ‐1.68] |
| 1.2 At intermediate follow‐up | 2 | 93 | Mean Difference (IV, Fixed, 95% CI) | ‐1.87 [‐2.45, ‐1.29] |
| 1.3 At intermediate follow‐up (6 months) | 1 | 40 | Mean Difference (IV, Fixed, 95% CI) | ‐0.3 [‐0.65, 0.05] |
| 2 Major adverse outcome Show forest plot | 2 | Risk Ratio (M‐H, Fixed, 95% CI) | Subtotals only | |
| 2.1 Failure of treatment: reduction was impossible requiring change in procedure | 1 | 53 | Risk Ratio (M‐H, Fixed, 95% CI) | 2.89 [0.12, 67.96] |
| 2.2 Failure of treatment (loss of reduction) | 2 | 93 | Risk Ratio (M‐H, Fixed, 95% CI) | 0.27 [0.05, 1.55] |
| 2.3 Infection | 1 | 53 | Risk Ratio (M‐H, Fixed, 95% CI) | 0.14 [0.01, 2.54] |
| 2.4 Hardware complications (irritation, broken or migration) | 2 | 93 | Risk Ratio (M‐H, Fixed, 95% CI) | 0.34 [0.16, 0.74] |
| 2.5 Delayed wound healing | 1 | 40 | Risk Ratio (M‐H, Fixed, 95% CI) | 0.2 [0.01, 3.92] |
| 2.6 Total adverse events | 2 | 93 | Risk Ratio (M‐H, Fixed, 95% CI) | 0.28 [0.14, 0.55] |
| 3 Observer‐rated measures of knee function Show forest plot | 2 | Std. Mean Difference (IV, Random, 95% CI) | Subtotals only | |
| 3.1 Knee function scores (KSCRS and Bostman score) at intermediate follow‐up | 2 | 93 | Std. Mean Difference (IV, Random, 95% CI) | 1.62 [0.49, 2.74] |
| 3.2 Knee function scores (KSCRS and Bostman score) at long‐term follow‐up ‐ 12 months | 2 | 86 | Std. Mean Difference (IV, Random, 95% CI) | 1.31 [‐0.07, 2.69] |
| 3.3 Knee function scores (KSCRS and Bostman score) at long‐term follow‐up ‐ 24 months | 2 | 84 | Std. Mean Difference (IV, Random, 95% CI) | 0.62 [0.18, 1.06] |
| 4 Knee range of motion: extension Show forest plot | 2 | Mean Difference (IV, Fixed, 95% CI) | Subtotals only | |
| 4.1 Extension (degrees) at short‐term follow‐up | 2 | 93 | Mean Difference (IV, Fixed, 95% CI) | 1.68 [0.74, 2.62] |
| 4.2 Extension (degrees) at intermediate follow‐up | 2 | 93 | Mean Difference (IV, Fixed, 95% CI) | 2.10 [1.27, 2.93] |
| 5 Knee range of motion: flexion Show forest plot | 2 | Mean Difference (IV, Fixed, 95% CI) | Subtotals only | |
| 5.1 Flexion (degrees) at short‐term follow‐up | 2 | 93 | Mean Difference (IV, Fixed, 95% CI) | 23.07 [17.79, 28.34] |
| 5.2 Flexion (degrees) at intermediate follow‐up | 2 | 93 | Mean Difference (IV, Fixed, 95% CI) | 33.29 [25.80, 40.78] |
| 5.3 Flexion (degrees) at long‐term follow‐up ‐ 12 months | 1 | 40 | Mean Difference (IV, Fixed, 95% CI) | 8.0 [1.12, 14.88] |
| 5.4 Flexion (degrees) at long‐term follow‐up ‐ 24 months | 1 | 40 | Mean Difference (IV, Fixed, 95% CI) | 8.30 [1.47, 15.13] |
| 6 Hardware removal (usually due to pain or subcutaneous irritation) Show forest plot | 2 | Risk Ratio (M‐H, Fixed, 95% CI) | Subtotals only | |
| 6.1 Hardware removal at intermediate follow‐up | 1 | 53 | Risk Ratio (M‐H, Fixed, 95% CI) | 0.53 [0.21, 1.39] |
| 6.2 Hardware removal at long‐term follow‐up | 2 | 93 | Risk Ratio (M‐H, Fixed, 95% CI) | 0.62 [0.43, 0.90] |
