Summary

Depending on location, anterior-based and posterolateral surgical approaches can both be effective for the treatment of posterolateral OCD lesions, however tibial tubercle osteotomy does not appear to significantly add to improved surgical exposure.

Abstract

Background

Osteochondritis dissecans (OCD) lesions of the lateral femoral condyle have a higher rate of instability and reduced rate of healing as compared to the more commonly described lesions of the medial femoral condyle. Unfortunately, lateral femoral condyle lesions are often located more posterior on the femoral condyle and thus more challenging to manage surgically. Effective, reproducible surgical approaches for operative management of lateral femoral condyle lesions have not been described. The aim of the study was to characterize reliable surgical exposure techniques for lateral femoral condyle OCD lesions.

Methods

This was a study of surgical approaches involving fresh whole-body cadaveric specimens (12 knees from 6 cadavers). All knees underwent a series of surgical approaches to evaluate the percentage of the articular surface that could then be adequately visualized. This included assessing the percentage of overall exposure of the lateral femoral condyle articular surface, as well as the percentage of exposure of the posterior region of the lateral femoral condyle articular surface (region encompassed by a line extending along the posterior cortex of the femur and its intersection with the femoral articular cartilage to the posterior articular chondral border of the femur). The following approaches were examined: lateral parapatellar, medial parapatellar with patellar eversion, lateral parapatellar with tibial tubercle osteotomy (TTO), medial parapatellar with TTO, posterolateral, and a posterior. Buried Kirschner wires were used to fluoroscopically demarcate the extent of exposure of the articular surface permitted by each surgical approach. One-factor analysis of variance (ANOVA) was used to compare mean surgical approach visualization percent differences. If a significant difference was detected, a Tukey post hoc test was conducted.

Results

The percentage exposure of the overall lateral femoral condyle for each approach were as follows: posterior 18.4%, posterolateral 27.3%, medial parapatellar with patellar eversion 76.8%, lateral parapatellar 80.1%, medial parapatellar with TTO 80.8%, and lateral parapatellar with TTO 84.4%. Of anterior-based approaches, there was a significant difference in the percentage of exposure of the lateral femoral condyle between the lateral parapatellar approach with TTO and the medial parapatellar approach with patellar eversion (84.4% vs. 76.8%, p=0.021), otherwise all other anterior-based approaches had a similar percentage of articular surface exposure. The lateral parapatellar approach with TTO provided the highest percentage of exposure involving the posterior region of the lateral femoral condyle (67.9%), however only the posterolateral and posterior approaches allowed visualization of the most posterior chondral region of the femoral condyle. The posterolateral approach had a significantly greater area of exposure of the posterior lateral femoral condyle than the posterior approach (62.3% vs. 41.4%, p<0.0001).

Conclusion

For OCD lesions involving the lateral femoral condyle, all anterior-based approaches can provide reliable exposure to the majority of the lateral femoral condyle articular surface. However, for lateral femoral condyle OCD lesions that extend far posteriorly, the posterolateral approach may be the most reliable approach to gain adequate exposure. Lastly, addition of a TTO does not appear to add significant improvement in exposure of the lateral femoral condyle articular surface versus a similar approach without TTO.