Wide Variability in the Radiographic Location of the Medial Patellofemoral Ligament Femoral Attachment: A Systematic Review and Meta-analysis.

Abstract

To systematically review and meta-analyze cadaveric studies quantifying the medial patellofemoral ligament (MPFL) femoral attachment site using radiopaque markers on radiographs to evaluate the accuracy of Schöttle's point as a radiographic landmark for MPFL attachment. A systematic review and meta-analysis was performed of the PubMed, EMBASE, and Scopus databases to identify cadaveric studies reporting the radiographic position of the MPFL femoral attachment. Included studies reported attachment location relative to the posterior cortical extension line in the anterior-posterior direction and to either the posterior point of Blumensaat's line or another radiographic landmark in the proximal-distal direction. The distance between Schöttle's point and other mean radiographic locations were calculated; distances greater than 3 mm, the radius of a femoral surgical tunnel, represented substantial variation. Nine studies of 94 cadaveric knees were included in the final analysis with a mean age of 62.45 ± 11.64 years. The average distance from the posterior cortical extension line to the MPFL insertion was 1.04 ± 10.09 mm anterior [95% CI: 0.40, 2.28, range: 4.80 mm posterior to 8.80 mm anterior] (n = 94). The average distance from Blumensaat's line was 2.07 ± 5.06 mm proximal [95% CI: 1.12, 2.00, range: 0.90 mm distal to 4.70 mm proximal] (n = 77). Three studies reported mean distance from the condylar transition line, averaging 2.88 ± 6.02 mm distal [95% CI: -5.04, -0.54, range: 0.50-5.70 mm distal] (n = 25). There was substantial heterogeneity in the radiographic location of the MPFL attachment, which suggests that relying solely on Schöttle's point risks nonanatomic tunnel placement. Although Schöttle's point is commonly used as a radiographic landmark during MPFL reconstruction, its variability suggests that the utilization of additional methods of assessment such as clinical palpation and graft isometry evaluation may enhance surgical precision and outcomes.