Elsevier

Academic Radiology

Volume 23, Issue 6, June 2016, Pages 724-729
Academic Radiology

Original Investigation
Magnetic Resonance Imaging of Osteochondritis Dissecans: Validation Study for the ICRS Classification System

https://doi.org/10.1016/j.acra.2016.01.015Get rights and content

Rationale and Objectives

In this retrospective case series, we utilize arthroscopy as the gold standard to determine if magnetic resonance imaging (MRI) of the knee can predict osteochondritis dissecans (OCD) lesion stability, the most important information to guide patient treatment decisions. It is hypothesized that the classification system of the International Cartilage Repair Society (ICRS) will allow for improved assessment of lesion grade and stability in OCD.

Materials and Methods

Routine MRI studies of 46 consecutive patients with arthroscopically proven OCD lesions (mean age: 23.7 years; 26 male, 16 female) were assessed by three radiologists who were blinded to arthroscopic results. Arthroscopic images were evaluated by two orthopedic surgeons in consensus. The OCD criteria of the ICRS were applied to arthroscopy and imaging interpretations. Inter-rater correlation statistics and accuracy of magnetic resonance (MR) grading with respect to arthroscopy were determined.

Results

Only 56% of the available MR reports assigned a label of stable or unstable to the lesion description. Of these, 58% of the lesions were deemed unstable and 42% were stable. Accuracy was 53% when reports addressed stability. Utilizing the ICRS classification system, for all three readers combined, the respective sensitivity, specificity, and accuracy of MR imaging to determine lesion stability were 70%, 81%, and 76%. When compared to the original MRI report, the overall accuracy increased from 53% to 76% when readers were given the specific criteria of the OCD ICRS classification. However, inter-reader variability remained high, with Krippendorf's alpha ranging from 0.48 to 0.57.

Conclusions

In this paper, we utilize arthroscopy as the gold standard to determine if MRI can predict OCD lesion stability, the most important information to guide patient treatment decisions. To our surprise, the analysis of the existing radiology reports that addressed stability revealed an overall accuracy in defining OCD lesion stability of about 53%. The classification system of the ICRS, created by an international multidisciplinary, multi-expert consortium, did markedly improve the accuracy, but consistency among different readers was lacking. This retrospective study on OCD reporting and classification highlights the inadequacy of existing classification schemes, and emphasizes the critical need for improved diagnostic MRI protocols in musculoskeletal radiology in order to propel it toward evidence-based medicine.

Introduction

Osteochondritis dissecans (OCD) is the term first utilized in 1887 (1) to describe the occurrence of a progeny osteochondral fragment separated from the parent bone. The etiology remains controversial (2) considering genetic (3), traumatic 4, 5, and vascular causes (6). In the knee, OCD most commonly occurs in the central aspect of the medial femoral condyle, followed by the lateral femoral condyle, the trochlea, and the patella (7). Treatment of OCD largely depends on the presence or absence of stability of the progeny and the parent bone 8, 9. Surgical fixation is recommended for stable OCD lesions that have failed nonoperative management, as well as for all unstable lesions 9, 10.

There is a general consensus that OCD lesion stability is determined based on both clinical and radiological examinations 11, 12, 13, 14. Magnetic resonance imaging (MRI) has been shown to be reliable in predicting the stability of OCD once a patient's physis has closed (15). However, the same research has shown poor correlation between magnetic resonance (MR) findings and stability on arthroscopy prior to skeletal maturity (15). Another study concluded that MRI should not be used in isolation to assess lesion stability in juvenile OCD (16). Frequently, stability is not specifically assessed on preoperative imaging reports. This has left the preoperative diagnosis of stability to be heavily based on clinical rather than imaging findings (9).

There are several arthroscopic classification systems that have been used (17). The International Cartilage Repair Society (ICRS) has attempted to create a more standardized and universally accepted system 17, 18. As higher grades are more likely to be unstable and need intervention, there is a utility to using a corresponding grading system in preoperative MR imaging (19).

The purpose of this study was to determine the accuracy and inter-rater variability of MR diagnosis of grade and stability of OCD in the knee as compared to the gold standard of arthroscopy using the ICRS classification system for both MRI and arthroscopic assessment. In this study, it is hypothesized that lesion grade and stability determination in OCD will be more accurate and consistent with specific assessment criteria than without.

Section snippets

Study Design and Patient Selection

This study was a retrospective review of consecutive patients with OCD of the knee from November 2006 through May 2014. The study was approved by the local institutional review board and performed in accordance with the Health Insurance Portability and Accountability Act (HIPAA) guidelines. Inclusion criteria were OCD in the knee, preoperative MR imaging, and arthroscopic images and report. Exclusion criteria were prior surgery on the same knee, nondiagnostic MR images, and nondiagnostic

Results

Forty-six cases of knee OCD lesions with arthroscopy, but no prior surgery on the same knee, were compiled between November 2006 and May 2014. Two patients were excluded for inadequate MR image quality, and two patients were excluded for inadequate quality of arthroscopic images. This resulted in 42 patients being included in the study, mean age of 23.7 years (range: 10–48 years) with 26 male (62%) and 16 female (38%) patients. These 42 patients were further subdivided into adults and juveniles

Discussion

The most important finding in the present study was that the analysis of the existing radiology reports revealed an overall low accuracy in defining OCD lesion stability of about 29% and that the ICRS classification system did markedly improve the accuracy to 76%, but consistency among different readers was lacking. Our findings are in keeping with several other publications highlighting the limited reliability of MRI imaging findings 15, 16 for evidence-based patient management. Several issues

Conclusions

In this paper, we utilize arthroscopy as the gold standard to define if MRI can predict OCD lesion stability, the most important information to guide patient treatment decisions. To our surprise, the analysis of the existing radiology reports revealed an overall accuracy in defining OCD lesion stability of about 29%. The classification system of the ICRS, created by an international multidisciplinary, multi-expert consortium, did markedly improve the accuracy, but consistency among different

Acknowledgment

We thank John Hughes, PhD, from the University of Minnesota, Department of Statistics, for the statistical analysis of the data.

References (31)

  • E.W. Edmonds et al.

    A review of knowledge in osteochondritis dissecans: 123 years of minimal evolution from Konig to the ROCK study group

    Clin Orthop Relat Res

    (2013)
  • J.D. Polousky

    Juvenile osteochondritis dissecans

    Sports Med Arthrosc

    (2011)
  • K.G. Shea et al.

    Osteochondritis dissecans development after bone contusion of the knee in the skeletally immature: a case series

    Knee Surg Sports Traumatol Arthrosc

    (2013)
  • B. Linden

    The incidence of osteochondritis dissecans in the condyles of the femur

    Acta Orthop Scand

    (1976)
  • M.S. Kocher et al.

    Management of osteochondritis dissecans of the knee: current concepts review

    Am J Sports Med

    (2006)
  • Cited by (38)

    • Good medium-term functional results in reconstruction of lateral femoral condyle osteochondral lesions

      2022, Orthopaedics and Traumatology: Surgery and Research
      Citation Excerpt :

      Review board and data protection authorization were obtained (n° 2019-A0027-56) and patients signed a consent form. Inclusion criteria comprised: (1) symptomatic focal lateral femoral condyle osteochondral lesion, (2) lesion secondary to ICRS (International Cartilage Repair Society) grade 3 or 4 OCD [34] or OCF, (3) age 16–40 years, and (4) stable knee or knee stabilized in the same step. Surgery was indicated for > 6 months’ persistent pain, knee iterative blockage episodes or effusion.

    View all citing articles on Scopus
    View full text