Gap Formation and Fixation Strength After Unicortical Quadriceps Tendon Repair with All-Suture Anchors

Background: All-suture anchors (ASAs) significantly reduced gap formation and increased strength compared with traditional fixation in a transosseous cadaveric quadriceps tendon repair model. However, the biomechanical performance of ASAs for unicortical quadriceps tendon repair has not been evaluated. Hypothesis: ASAs would reduce gap formation and exhibit comparable stiffness, yield load, and ultimate load to knotless hard-body suture anchors (SAs) for unicortical quadriceps tendon repair. Study Design: Controlled laboratory study. Methods: Eight matched pairs of male cadaveric knees were used to compare ASA and SA control repairs. Distal quadriceps tendons were prepared with 2 Krackow sutures using 1.3-mm suture tape. Sutures were fixed unicortically with 2 anchors using 2.6-mm ASAs or 4.75-mm SAs. Knees were actuated from 5° to 90° of flexion via the quadriceps tendon for 10 native preconditioning cycles and 250 cycles after repair at 0.1 Hz, with a peak force of 150 N per cycle. Repairs were loaded to failure at 50 mm/min. Gap formation (mm) during cyclic loading and stiffness (N/mm), yield load (N), and ultimate load (N) during load to failure were statistically compared between groups using paired t tests. Results: The ASA repair had significantly less gap formation at cycle 250 compared with the control repair (Δ = 4.2 mm [95% CI, 2.9 to 5.3 mm]; P < .001) and survived greater cycles before reaching a critical gap threshold of 5 mm (200 vs 50 cycles). No significant differences in stiffness or ultimate load were found between repairs. The yield load was significantly greater in the control group than the ASA group (Δ = 55 N [95% CI = 27-82 N]; P = .002). Conclusion: Unicortical quadriceps tendon repair with ASAs reduced gap formation by 43% compared with hard-body SAs. No significant differences in stiffness or ultimate load were observed, although a significantly greater yield load was found for the SA controls. Clinical Relevance: ASAs are a biomechanically viable alternative to hard-body SAs for unicortical quadriceps tendon repair, potentially resulting in less gap formation.