Variability in the Patellar Attachment of the Medial Patellofemoral Ligament

Purpose To describe and quantify the variability of the attachments of the medial patellofemoral ligament (MPFL). Methods Thirty-three cadaveric knees were dissected, and the MPFL was identified from the articular side after anterior reflection of the extensor mechanism and removal of the synovium. The width of the MPFL at its femoral origin and anterior attachment was measured using digital calipers once by 1 examiner. The percentage of fibers that attached to the patella versus the quadriceps tendon was calculated relative to the width of the total attachment. The length of the MPFL fibers was measured from the femoral origin to (1) the patella and (2) the quadriceps tendon and compared using paired t tests. Results Four knees had no identifiable MPFL fibers, and 1 was excluded because of the presence of osteophytes. In 28 knees, the mean width of the MPFL was 10.7 ± 1.8 mm at the femoral origin and 30.4 ± 5.5 mm at the patellar attachment. One knee had all MPFL fibers attaching to the patella, and another had all fibers attaching to the quadriceps tendon. The remainder had attachments to both structures, with 57.3% ± 19.5% (range, 0% to 100%) of fibers attaching to the patella. Mean length of the MPFL fibers was 62.6 ± 5.2 mm from the femoral origin to the patella and 69.7 ± 5.5 mm from the femoral origin to the quadriceps tendon (7.1-mm difference; P <.0001). Conclusions MPFL fibers vary in their width and percentage of attachments to the patella and quadriceps tendon. Further studies are needed to identify the appropriate fixation points to re-create the anatomy and isometry of the MPFL during reconstruction for patellar stabilization. Clinical Relevance Variability in the anatomy of the MPFL suggests that optimal anatomic graft placement may vary during reconstruction of this ligament.