Transosseous Quadriceps Tendon Repair With Knotless All-Suture Anchors Is Biomechanically Superior to Traditional Transosseous Fixation.

BACKGROUND

Reruptures and functional deficits can occur with conventional transosseous quadriceps tendon repair. Previous work has demonstrated the biomechanical superiority of adjustable transosseous metal cortical button fixation over conventional repair. Knotless all-suture anchor (ASA) buttons may provide a similar improvement but have not yet been investigated.

PURPOSE

To biomechanically compare adjustable transosseous cortical fixation with knotless ASAs to traditional transosseous repair.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eight matched pairs of male cadaveric knees were dissected to isolate and release the quadriceps tendon insertion. Paired knees were randomized to 2.6-mm knotless ASA or control repair, both with Krackow suturing using 1.7-mm suture tape. The ASA technique had two 1.6-mm tunnels through which the knotless ASA loops interlocked with the Krackow sutures. The control technique had three 2.4-mm tunnels through which suture tape tails were passed and tied over bone bridges. Knees were mounted onto a materials testing system and actuated from 5° to 90° of flexion via the quadriceps tendon for 10 native preconditioning cycles and 250 cycles after repair 0.1 Hz, with a peak force of 150 N per cycle. Repairs were loaded to failure at a rate of 50 mm/min. Outcomes included plastic gap formation (mm) during cyclic loading and stiffness (N/mm), yield load (N), and ultimate load (N) during load to failure. Paired tests were used for statistical analysis ( < .05).

RESULTS

The ASA had significantly less gap formation at cycle 250 (mean Δ = 6.3 mm; < .001) and superior stiffness (Δ = 17.7 N/mm; = .004), yield load (Δ = 40 N; = .014), and ultimate load (Δ = 127 N; = .015) compared with the control. The mean transosseous control displacement surpassed the defined critical threshold for gap formation (5.0 mm) in this study by cycle 50, whereas the mean ASA displacement never did.

CONCLUSION

Compared with conventional transosseous quadriceps tendon repair, adjustable ASA transosseous repair had 64% less tendon-bone gap formation, 35% greater stiffness, 21% greater yield load, and 27% greater ultimate load.

CLINICAL RELEVANCE

Adjustable knotless ASA cortical fixation is a viable alternative for transosseous quadriceps tendon repair that increases repair strength and reduces patellar tunnel drilling.