Significant Variation in Quadriceps Tendon Thickness Is Observed Among Cadaveric Specimens

Abstract

Purpose

To evaluate variation in quadriceps tendon (QT) morphology in cadaveric specimens, focusing on tendon thickness, and to improve current QT harvesting techniques and graft preparation for anterior cruciate ligament (ACL) reconstruction.

Methods

Eight fresh-frozen, skeletally mature, midthigh-to-toe cadaveric legs with no history of knee surgery and at least 65 mm of tendon were utilized. There were 4 males and 4 females. The average donor age was 80.4 years (range, 69-93 years), and the average height was 66.1 inches (range, 59 to 72 inches). The tendon was exposed with an open extensile approach via a longitudinal midline incision. Tendon thickness was measured using calipers at the superior pole of the patella and 65 mm proximal to the insertion. Univariate analysis was used to generate sample means, standard deviations, and 95% confidence intervals (CIs).

Results

Tendon thickness at the distal patellar insertion site was a mean (standard deviation [SD]) of 8.7 (1.4) mm. At 65 mm proximal to the patellar insertion site, the mean (SD) thickness of the tendon was 6.5 (1.1) mm. The 95% CIs were 7.7 to 9.7 mm for the distal insertion and 5.8 to 7.2 mm for the proximal tendon. The 2 measurement sites had a mean (SD) difference of 2.2 (0.7) mm (95% CI, 1.6-2.8 mm; P < .001). Overall, the proximal tendon showed a reduction in thickness by a mean (SD) of 25.3% (6.7%) compared to the thickness at the patellar pole.

Conclusions

Quadriceps tendons had a significant decrease in thickness, measuring distally to proximally. However, the thickness was not uniform, and the variation was high among specimens tested.

Clinical Relevance

Anatomic variations in QT thickness may contribute to variable graft diameters in ACL reconstruction, highlighting the importance of accounting for tendon morphology for graft preparation, ACL tunnel position, and size.