Patellar tendon repair with hamstring autograft: A cadaveric analysis

Background: Rupture of the patellar tendon requires surgical repair to restore function of the knee. The most accepted repair technique utilizes running locking non-absorbable sutures secured to the patella through three drill holes. Complications with this repair technique include rerupture, knee stiffness, and extensor lag caused by gap formation at the site of repair. Some surgeons have suggested augmenting the standard repair with local autograft tendon to avoid these complications. It was hypothesized that using a repair technique that included augmentation of the repair with autograft tendons would decrease the gap formation at the repair site under cyclic loading conditions. Methods: In this experiment, eight specimens were used to analyze two methods of patellar tendon repair: hamstrings autograft augmentation and a standard repair using three vertical bone tunnels in the patella. Each specimen was then extended with a 2.2 kg weight on the tibia at 0.25 Hz to simulate early motion after surgery. The gap formed at the repair site was then measured at 1, 10, 100, and 250 cycles and both techniques confidence interval compared using a Wilcoxon signed rank test. Findings: The mean gap formation for the standard repair after one cycle was 8.9 mm (SD 2.4) and for the augmented repair was 3.6 mm (SD 0.9). At 250 cycles the mean gap formed for the standard repair was 13.2 mm (SD 1.9) and the mean gap for the augmented repair was 7.2 mm (SD 0.9). All gaps for all cycles analyzed had an 88% confidence interval for significance using a Wilcoxon signed rank test. Interpretation: The biomechanical results of this study show statistical trend toward decrease gap formation with an augmented tendon at the repair site under a simulated dynamic knee motion.