Measurement of distance between femoral insertion of fibular collateral ligament and popliteus tendon: A magnetic resonance imaging based study.

BACKGROUND

Fibular collateral ligament (FCL), popliteus tendon (PT) and popliteofibular ligament are key components of posterolateral corner (PLC) of the knee. These structures play a vital role in stabilizing the knee against varus and external rotation. The Anatomical location of these structures should be well understood for adequate reconstruction of PLC injuries.Purpose of our study is to measure mean distance between femoral insertion of FCL and PT; femoral medio-lateral dimension (MLD) and antero-posterior dimension (APD) of lateral femoral condyle on Magnetic Resonance Imaging (MRI) images and its relevance to anatomical reconstruction of PLC injuries of knee.

METHODS

The knee MRI data of 68 patients (43 males and 25 females) were studied. Measurement of PT-FCL distance was done in sagittal proton density fat-saturated (PDFS) sequence images. The femoral MLD and APD were measured in axial PDFS sequence images. The mean of each parameter was calculated and analyzed. To identify inter-observer agreement, we calculated (ICC) for each parameter.

RESULTS

The mean PT-FCL distance was 16.85 ± 1.55 mm (range 12.9-21.2 mm). In our observation, PT always inserts anteriorly and distally to FCL insertion on the lateral femoral condyle. The mean MLD was 78.74 ± 5.84 mm (range 65-90 mm). The Mean APD of the lateral femoral condyle was 60.47 ± 4.00 mm (range 52.5-69.5 mm). The difference between the mean values of all the above parameters in both genders was statistically significant (p-value <0.05). Inter-observer agreement was very good for measurement of PT-FCL distance (ICC 0.96), MLD (ICC 0.98) and APD (ICC 0.97).

CONCLUSION

The mean distance between femoral insertion of FCL and PT in our study was less in comparison to most of the western literature. However, despite this anatomical variation, the method of PLC reconstruction proposed in western literature can be safely advocated in the Indian population as well.