Strength of the fixation of patellar tendon bone grafts using a totally absorbable self-reinforced poly-L-lactide expansion plug and screw. An experimental study in a bovine cadaver

doi:10.1016/S0749-8063(96)90035-3

Arthroscopy: The Journal of Arthroscopic & Related Surgery

Volume 12, Issue 4, August 1996, Pages 422-427

https://doi.org/10.1016/S0749-8063(96)90035-3 Get rights and content

Abstract

In a bovine cadaver study, bone-tendon-bone graft fixation strength with different graft geometry and fixation devices was measured to evaluate the fixation strength of totally absorbable implants: a 6.0-mm expansion plug and 6.3-mm screw both made of self-reinforced polylactide (SR-PLLA). Comparison was made with 6.5-mm AO cancellous screw. Maximum tensile force to dislodge the bone plug from the bone tunnel was recorded. First, two preliminary tests were performed. In the first test, triangular bone plugs were used (9-mm diameter). The direction of the pull force was parallel to the bone tunnel. The maximum tensile forces were 786 N in femoral insertions and 625 N in tibial insertions, mean. After this, we evaluated the influence of change in the pullout direction. In the second test, a circular bone plug was used with no fixation but the direction of the pull force was parallel to the tibial or femoral axis and the bone plug (10-mm diameter) was in a 30° to 40° angle to the direction of the pull force and it was compressed to the tunnel (9-mm diameter). The maximum tensile forces were 783 N in femoral insertions and 695 N in tibial insertions, mean. In the final third test, we used a curved saw in harvesting the graft. This made a half-circular bone block with a diameter of 12 mm. The maximum tensile force to dislodge the bone plug from the bone tunnel was recorded and the pull force was in a 30° to 40° angle to the tunnel. The results were evaluated with Student's t-test and Mann-Whitney U-test. With the AO screw, the maximum tensile force to dislodge the bone plug from the bone tunnel was 2,113 ± 407 N (mean ± standard deviation) and it was better than the fixation strength of the SR-PLLA expansion plug, 1,379 ± 328 N (P = .009, t-test) and better than the fixation strength of SR-PLLA screw, 1,454 ± 230 N (P = .007, t-test). However, the maximum tensile force of both SR-PLLA implants in all measurements in the third test were above 1,100 N and it seems that the initial strength of totally absorbable implants is enough for the clinical use.

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Cited by (22)

Bone block fixation by ultrasound activated resorbable pin osteosynthesis: a biomechanical in vitro analysis of stability
2010, Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology and Endodontology
Citation Excerpt :
However, the determined tensile forces, 80-100 N, match the results of other authors.24 Many authors applied the same experimental design, performing pull-out tests on screws.25-33 Nunamaker and Perren34 and Bluemlein et al.35,36 used small tension-measuring detectors for the measurement of axial forces on osteosynthesis screws.
The aim of this study was to determine the compound strength of the fixation between 2 blocks of synthetic bone using ultrasound activated resorbable pins (regarding drill hole diameter) and compare them to fixation with titanium miniscrews. Resorbable pins were up to 17 mm long.
Two synthetic bone blocks (Sawbone) were fixed by either a resorbable pin or miniscrew osteosynthesis. Maximum tensile forces were determined mechanically. Pin lengths of 7 mm, 11 mm, and 17 mm were analyzed in relation to different drill hole diameters.
The ideal drill hole configuration was a combination of diameters of 2.1/1.6 mm (in a lag screw configuration). Mean maximum tensile force was 80 N for 7 mm pins (105 N/11 mm, 69 N/17 mm). In comparison, tensile forces of titanium screws were 20 N (7 mm), 97 N (11 mm), and 135 N (17 mm).
Osteosynthesis by resorbable pins reached equal compound strength levels compared with titanium miniscrews. This in vitro study was the basis for a clinical trial of ultrasound-guided resorbable pin osteosynthesis.
A new device for the fixation of anterior cruciate ligament tendon grafts. Design and experimental study
2007, Medical Engineering and Physics
In this paper the design and experimental analysis is presented of a new fixation device of anterior cruciate ligament (ACL) grafts of the knee. This device is inserted into the bone tunnel, after the graft, in the same way as an interference screw. However, the fixation device described in this paper has been designed in such a way that, after the insertion of a threaded element in its interior, some of its components expand in a radial direction, pressing against the walls of the bone tunnel and thereby increasing the fixation of the graft. This expansion device can be used in both the femur and the tibia.
The device proposed in this paper was compared with an interference screw for load failure and fixation stiffness in experiments performed using porcine bones. The failure load was significantly higher in the new expansion device group (633 ± 202 N) than in the interference screw group (471 ± 179 N). The stiffness obtained when the new device was used (59 ± 20 N/mm) was also significantly higher than that obtained using the interference screw (37 ± 19 N/mm) (t-test, P < 0.05). According to these results, this new device could be considered a good alternative to improve fixation of anterior cruciate ligament grafts.
Quadriceps tendon impingement from a femoral interference screw
2003, Arthroscopy
Citation Excerpt :
Good results have been reported after ACL reconstruction with hamstring grafts fixed with metallic interference screws.4 However, nonmetallic interference screw fixation has been recommended by some researchers because of concerns about potential graft laceration from metallic threads and metallic implants interfering with future knee imaging studies.7 Unfortunately, use of nonmetallic implants makes confirming the position of the implants difficult, if not impossible, on plain radiographs.
Interference screws are a popular method of securing tendon grafts during anterior cruciate ligament reconstruction. This report describes the case of a patient with anterior knee pain, limited flexion, and partial-thickness tear of the quadriceps tendon caused by a protruding femoral interference screw following hamstring tendon anterior cruciate ligament reconstruction. The interference screw was radiolucent, requiring magnetic resonance imaging to visualize its location. Removal of the protruding portion of the interference screw and debridement of the partial-thickness tear of the quadriceps tendon led to rapid restoration of knee flexion and alleviation of the anterior knee pain.
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 19, No 4 (April), 2003: pp E34–E34
Primary stability with tibial press-fit fixation of patellar ligament graft: An experimental study in ovine knees
2001, Arthroscopy
Citation Excerpt :
With fixation on the cortical side, either block fracture or ligamentous rupture will occur. In their report, Tuompo et al.15 emphasized the importance of the bone block/ligament angle for the primary stability of the graft. It was shown that angulations of at least approximately 30° to 40° provided for a 3-fold load-to-failure.
Purpose: To investigate the initial fixation strength and to assess the value of tibial press-fit fixation of the bone-tendon-bone graft in anterior cruciate ligament reconstruction. Type of Study: Nonrandomized control trial. Methods: For tibial press-fit fixation, the tibial bone block of the bone-tendon-bone graft is countersunk in a bony groove at the distal tunnel outlet and fixed over a bone bridge with 2 No. 6 Ethibond sutures. The bone cylinder harvested from the tibial tunnel using an oscillating hollow saw is plugged into the tibial tunnel parallel to the graft, thus providing for additional anchoring of the graft by tibial press-fit fixation. In a comparative experimental study in 46 ovine knees, this fixation method was assessed for its value in anterior cruciate ligament reconstruction. A tibial bone tunnel was placed in routine manner in each ovine tibia using a target drill unit and an oscillating hollow saw. The complete patellar ligament, proximally attached to the patella and distally to a cylindrical bone block (20 × 8.4 mm), served as graft. Tibial fixation in group A (n = 10) was done using a titanium interference screw (20 × 8 mm), in group B (n = 10) using a titanium staple, in group C (n = 12) using suture fixation over a bone bridge, and in group D (n = 14) using the press-fit fixation described above. In a materials testing machine, all specimens were subjected to continuously increasing load until failure at a velocity of 1 mm/second. Ultimate failure load, stiffness, stress-strain characteristics, and failure mode were evaluated. Results: Ultimate load to failure was 572 N (range, 473 to 680 N) in group A, corresponding to a fixation stiffness of 17.68 N/mm. For group B, ultimate load to failure was 608.4 N (range, 511 to 727 N) and stiffness of 19.92 N/mm. Bone block dislocation was the failure mode in groups A and B. Group C with exclusive suture fixation showed an ultimate load to failure of 304.5 N (range, 120 to 327 N) and a stiffness of only 6.96 N/mm. The mode of failure was suture cutout caused by the bone block in 9 of the cases and untying of the suture knot in 3 cases. Group D with press-fit fixation showed a significantly higher primary stability of 758 N (range, 513 to 993 N) relative to group C, with a corresponding stiffness of 25.12 N/mm (P <.02). In this group, the mode of failure was ligamentous rupture from the bone block. Regarding mechanical properties, no significant differences were seen between groups A, B, and D. Conclusions: Tibial press-fit fixation allows for metal-free fixation with high primary stability. By refilling the bone tunnel, the ligament (with a rather small cross-sectional diameter compared with hamstrings) is safely fixed within the bone tunnel to prevent potential postoperative tunnel enlargement due to movement of the graft within the tunnel. Anchoring the graft at the entrance into the joint, it provides for reduced graft length and adequate elasticity and accomplishes the requirements of fixation at the correct anatomic insertion site.
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 9 (November-December), 2001: pp 963–970
Bioabsorbable polyglyconate interference screw fixation in anterior cruciate ligament reconstruction: A prospective computed tomography -Controlled study
2000, Arthroscopy
Citation Excerpt :
In the case of bioabsorbable screws, holding strength must be maintained up to this time despite degradation of the implant. Initial pullout strength in vitro has proved to be sufficient for most biodegradable screws.8,33,34 The CT images in our study showed bone block ingrowth between 6 and 12 weeks.
Purpose: It was the purpose of the study to evaluate a new polyglyconate bioabsorbable interference screw for graft fixation in anterior cruciate ligament (ACL) reconstruction. Type of Study: Prospective randomized. Materials and Methods: Forty patients who underwent endoscopic ACL reconstruction were included in the study and randomized intraoperatively. Group A consisted of 20 patients (6 women, 14 men; mean age, 29.6 years) who had femoral bone block fixation with a bioabsorbable interference screw and tibial fixation with a titanium interference screw. Group B included 20 patients (5 women, 15 men; mean age 29.6 years) who had fixation of both femoral and tibial bone blocks with titanium interference screws. There was no significant difference between the groups with regard to age, gender, height, weight, time from injury to surgery, activity level, and concomitant injuries. Results: Clinical results (using IKDC, Lysholm, Tegner scores) of the 2 groups as well as instrumented laxity measurements (KT-1000) did not show significant (P >.05) differences at any stage of follow-up. No complications with respect to graft fixation could be found. Computed tomography scans, performed within the first postoperative week, at 6 weeks, and at 3, 6, 12, and 24 months postoperatively revealed a uniform picture for all patients within the groups, showing completed screw degradation at 12 months in group A. Conclusion: Polyglyconate interference screw fixation for patellar tendon grafts has not been found to be associated with increased clinical complications or significant osteolysis. It provided equivalent fixation and clinical results compared with titanium screws. However, replacement of the screw with bone did not take place for up to 3 years postoperatively.
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 16, No 5 (July), 2000: pp 491–498
Is screw divergence in femoral bone-tendon-bone graft fixation avoidable in anterior cruciate ligament reconstruction using a single-incision technique? A radiographically controlled cadaver study
2000, Arthroscopy
Citation Excerpt :
ACL graft fixation in the bony tunnel is still a point of concern in knee ligament surgery and the object of intensive research. A trend toward accelerated rehabilitation programs and the use of bioabsorbable implants underlines the importance of sufficient initial early fixation.11,12,21,22 Interference screw fixation of patellar bone-tendon-bone grafts has proven to be a reliable method and has been shown to provide pullout strength exceeding that afforded by fixation with staples, cortical screws, or sutures over buttons.13,14,23
Summary: Interference screw fixation of patellar tendon bone-tendon-bone grafts for anterior cruciate ligament reconstruction has proven to be a method with high pullout strength if screw divergence is avoided. Twenty-four fresh-frozen cadaveric human knees were used to identify the ideal position for a portal and an optimal knee flexion angle to obtain parallel placement of screw and bone block. On all specimens, anterior cruciate ligament reconstruction was performed using a single-incision technique. In the first part of this study, screw placement was analyzed in the frontal plane. In the second part, screw placement was investigated in the sagittal plane, measuring the additional flexion required between femoral tunnel drilling (at 60° of knee flexion) and screw insertion to obtain parallel screw placement. For both part I and II, image intensification was used. In the third part, femoral screw placement was carried out through a paraligamentous approach and with additional flexion of 10°, 20°, 30°, 40°, 50°, and 60°. This study shows that screw placement with minimal divergence in the frontal and sagittal planes can be achieved by inserting the screw through a nearly central portal and flexing the knee an additional 35° to 40°.
Arthroscopy: The Journal of Arthroscopic and Related surgery, Vol 16, No 6 (September), 2000: pp 640–647

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^☆: Supported by Research grants from The Academy of Finland and the Finnish Orthopaedic Foundation.

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Original articleStrength of the fixation of patellar tendon bone grafts using a totally absorbable self-reinforced poly-L-lactide expansion plug and screw. An experimental study in a bovine cadaver☆

Abstract

Arthroscopy

Arthroscopy

Arthroscopy

Lancet

Arthroscopy

Biomechanical analysis of human ligament grafts used in knee-ligament repairs and reconstruction

J Bone Joint Surg Am

Reconstruction of the anterior cruciate ligament: A new technique using the central one-third of the patellar ligament

J Bone Joint Surg Am

Vascularized patellar tendon graft with rigid internal fixation for anterior cruciate ligament insufficiency

Clin Orthop

A biomechanical comparison of different surgical techniques of graft fixation in anterior cruciate ligament reconstruction

Am J Sports Med

Original article
Strength of the fixation of patellar tendon bone grafts using a totally absorbable self-reinforced poly-L-lactide expansion plug and screw. An experimental study in a bovine cadaver☆