Background: Patellar tendon ruptures commonly are repaired using transosseous patellar drill tunnels with modified-Krackow sutures in the patellar tendon. This simple suture technique has been associated with failure rates and poor clinical outcomes in a modest proportion of patients. Failure of this repair technique can result from gap formation during loading or a single catastrophic event. Several augmentation techniques have been described to improve the integrity of the repair, but standardized biomechanical evaluation of repair strength among different techniques is lacking. Questions/purposes: The purpose of this study was to describe a novel figure-of-eight suture technique to augment traditional fixation and evaluate its biomechanical performance. We hypothesized that the augmentation technique would (1) reduce gap formation during cyclic loading and (2) increase the maximum load to failure. Methods: Ten pairs (two male, eight female) of fresh-frozen cadaveric knees free of overt disorders or patellar tendon damage were used (average donor age, 76 years; range, 65–87 years). For each pair, one specimen underwent the standard transosseous tunnel suture repair with a modified-Krackow suture technique and the second underwent the standard repair with our experimental augmentation method. Nine pairs were suitable for testing. Each specimen underwent cyclic loading while continuously measuring gap formation across the repair. At the completion of cyclic loading, load to failure testing was performed. Results: A difference in gap formation and mean load to failure was seen in favor of the augmentation technique. At 250 cycles, a 68% increase in gap formation was seen for the control group (control: 5.96 ± 0.86 mm [95% CI, 5.30–6.62 mm]; augmentation: 3.55 ± 0.56 mm [95% CI, 3.12–3.98 mm]; p = 0.02). The mean load to failure was 13% greater in the augmentation group (control: 899.57 ± 96.94 N [95% CI, 825.06–974.09 N]; augmentation: 1030.70 ± 122.41 N [95% CI, 936.61–1124.79 N]; p = 0.01). Conclusions: This biomechanical study showed improved performance of a novel augmentation technique compared with the standard repair, in terms of reduced gap formation during cyclic loading and increased maximum load to failure. Clinical Relevance: Decreased gap formation and higher load to failure may improve healing potential and minimize failure risk. This study shows a potential biomechanical advantage of the augmentation technique, providing support for future clinical investigations comparing this technique with other repair methods that are in common use such as transosseous suture repair.
Bibliographical noteFunding Information:
We thank the Washington University Musculoskeletal Research Core NIH P30 AR057235 (St Louis, MO, USA) for laboratory space, equipment and technical support, and Daniel Leib MS (Musculoskeletal Research Center, Washington University Department of Orthopaedics, St Louis, MO, USA) for providing technical laboratory assistance. We also thank Scott Bodell (Bodell Communications Inc, Dallas, TX, USA) for creation of medical illustrations. The institution of one of the authors (JCB) has received, during the study period, funding from the AOTrauma North America. One of the authors certifies that he (JCB), has received payments, during the study period, an amount of USD 10,000-USD 100,000 from the AOTrauma North America (Paoli, PA, USA).
© 2016, The Association of Bone and Joint Surgeons®.