Femoral radiographic landmarks for popliteus tendon reconstruction and repair: a new method of reference

Background: Although the popliteus muscle-tendon complex is one of the most important structures in controlling posterolateral rotatory stability of the knee, not much literature has been reported concerning the use of femoral radiographic landmarks of the popliteus tendon in repair and reconstruction.

Hypothesis: By using standardized radiographic techniques, the femoral insertion of the popliteus tendon could be more precisely determined by the Blumensaat line than by the extension line of the posterior cortex.

Study design: Descriptive laboratory study.

Methods: Ten fresh-frozen human knees were dissected, and the popliteus tendon was exposed. After identification of the femoral insertion site of the popliteus tendon, the insertion's center was indicated with a radiographic marker. True lateral radiographs of the distal femur were taken, and the digital radiographic images were analyzed by 2 independent observers.

Results: The femoral insertion site of the popliteus tendon was found to be a mean 47.5% ± 5.2% across the width of the femoral condyle, 60.7% ± 7.8% along the perpendicular bisector of the Blumensaat line, 0.3 ± 1.7 mm posterior to the extension line of the posterior femoral cortex, and 20.5 ± 3.8 mm distal to the perpendicular line at the Blumensaat point. The variance from the mean point by using the Blumensaat line as a reference was significantly smaller than by using the extension line of the posterior cortex (mean, 2.6 vs 3.6 mm; P = .044).

Conclusion: A reproducible anatomic and radiographic reference point for the femoral insertion of the popliteus tendon can be determined using standardized radiographic techniques and can be more precisely determined by the Blumensaat line compared with the extension line of the posterior femoral cortex.

Clinical relevance: This radiographic information provides an adjunctive tool for preoperative, intraoperative, and postoperative assessments of surgical repair and reconstruction of the popliteus tendon.