Purpose

To report the radiographic landmarks for the medial patellofemoral complex (MPFC) footprint on the medial femur and describe the difference between the radiographic landmarks corresponding to the medial quadriceps tendon femoral ligament (MQTFL) and medial patellofemoral ligament (MPFL) fibers.

Methods

In 8 unpaired cadaveric knees, the MPFC footprint was exposed on the medial femur, and the proximal and distal boundaries of the footprint were marked. Lateral fluoroscopic images of the knee were obtained and analyzed using Image J. The proximal MQTFL boundary (Q1) and midpoint of the MPFC (M1) and distal MPFL boundary (P1) were described as percentage of femoral condylar height (FCH, with 0-100% being distal to proximal) and femoral condylar width (FCW, with 0-100% being posterior to anterior). All measurements were compared using one-way ANOVA with post-hoc Tukey HSD. A p value < 0.05 was considered statistically significant.

Results

On fluoroscopic views, Q1 was 111 ? 6.9% FCH from the distal condyle and 39.1 ± 6.5% FCW from the posterior condyle. M1 was 96.9 ? 7.8% FCH from the distal condyle and 37.2 ± 5.3% FCW from the posterior condyle, while P1 was 81.5 ? 8.7% FCH and 35.7 ± 4.3% FCW respectively. Moreover, M1 was 14.2 ± 3.9% FCH, or 5.1 ± 3.5mm, distal (p = .004) and 1.9 ± 2.3% FCW, or 1.1 ± 1.3mm, posterior to Q1 (p = .499); while P1 was 15.4 ± 3.2% FCH, or 5.5 ± 1.1mm, distal (p = .002) and 1.5 ± 1.9% FCW, or 0.8 ± 1.0mm, posterior to M1 (p = .596). P1 was 29.6 ± 6.7% FCH, or 10.6 ± 2.4mm, distal (p <.001) and 3.3 ± 3.9% FCW, or 1.9 ± 2.2mm, posterior to Q1 (p = .234).

Conclusion

On fluoroscopy, proximal MQTFL and distal MPFL fibers have significantly different radiographic positions. Because fluoroscopy is often utilized intraoperatively to guide graft placement, our findings may serve as a reference when differentiating the locations of the MPFL vs MQTFL on the femur during reconstructive procedures.