Objective: The aim of this study was to compare different patellar tendon repair constructs.

Materials and Methods: Eight pairs of cadaveric legs were used to compare metal suture anchor repair with “standard” Krakow tendon suture through patella bone tunnels and steel box wire augmentation loop repair. Each leg was retested with box wire augmentation loop and simple 2/0 polyglactin suture repair.

The repairs were tested by mounting the legs on a specially designed rig on a materials testing machine which allowed the leg to be cycled from 90° knee flexion to full extension. The specimens were cycled 1000 times at 0.25Hz or until the repair failed. Optical markers were attached to the leg which enabled the repair gap and knee angle to be monitored during testing (Smart Capture and Analyser Tracking system, Padua, Italy).

Results: Six out of eight suture anchor repairs failed, all suture bone tunnel repairs with augmentation loops completed 1000 cycles. One out of 16 augmentation loop with simple 2/0 suture repair failed.

For all specimens regardless of repair type that completed 1000 cycles there was no significant difference in repair gap distance.

Conclusion: Suture anchors alone do not provide a strong enough construct for patellar tendon repair.

The box wire augmentation loop is key to maintaining patellar tendon repair.

Krakow tendon sutures secured through patellar bone tunnels do not provide additional benefit to a simple appositional suture and box wire augmentation loop.