Biomechanical Comparison of Transosseous Knotless Rotator Cuff Repair Versus Transosseous Equivalent Repair: Half The Anchors With Equivalent Biomechanics?

PURPOSE: To compare the biomechanics of a transosseous equivalent (TOE) repair using medial and lateral anchors with tape to a transosseous knotless (TOK) tape repair with only laterally placed intraosseous anchors. METHODS: One of 2 different repairs were performed on 8 paired specimens: (1) transosseous equivalent (TOE) tape repair or (2) transosseous knotless (TOK) tape repair. Specimens were mounted on a materials testing machine and loaded in uniaxial tension to measure cyclic construct gap formation, followed by failure testing. Paired t tests were used to compare gapping, ultimate stiffness, and failure loads. Fisher exact test was used to compare modes of failure (soft tissue failure vs construct failure). RESULTS: Peak cyclic gapping, failure stiffness, and ultimate failure loads did not differ between TOE and TOK repairs (P = .140 for gapping, P = .106 for stiffness, and P = .672 for peak failure loads). All TOK repairs failed via soft tissue failure medial to the medial suture line, with no construct failures. TOE repairs failed more often through construct failure (anchor migration or suture-bone interface cut through) than TOK repairs (P = .026). CONCLUSION: TOK repairs only failed through soft tissue whereas TOE repairs failed through both soft tissue and the repair construct. Despite 50% fewer suture anchors in the TOK repairs than the TOE repairs, cyclic gapping and ultimate stiffness and failure loads were not significantly different. CLINICAL RELEVANCE: The transosseous knotless construct presented is a 2-anchor construct that is equivalent in biomechanical function to a traditional 4-anchor construct, reducing anchor load in the tuberosity.

Efficacy of osteogenic protein-1 in a challenging multilevel fusion model.

STUDY DESIGN: A therapeutic study compared the influence of osteogenic protein-1 to autograft and collagen carrier in multilevel sheep spine fusions. OBJECTIVE: To evaluate the efficacy of osteogenic protein-1 compared to autograft and collagen carrier in achieving fusion in a challenging multilevel lumbar spine ovine model. SUMMARY OF BACKGROUND DATA: Bone morphogenetic proteins can successfully augment spinal fusion. To date, all the preclinical and clinical studies using bone morphogenetic proteins have evaluated single-level fusion. In practice, multiple level fusions are commonly required for various conditions, like spinal deformity. METHODS: Eighteen sheep underwent three-level spine fusion. Six sheep were treated with osteogenic protein-1 and its carrier, autograft, or with the carrier alone. Specimens were analyzed for evidence of fusion by palpation, radiographic and histologic analysis, and biomechanical testing. RESULTS: Manual palpation testing for the presence of fusion showed none of the specimens fused all three levels or fused at the lumbosacral junction. No statistically significant difference was found between the osteogenic protein-1 and autograft groups' fusion rates based on radiographic grading (P = 0.65) or biomechanical testing. Histologic analysis showed no qualitative difference in bone morphology or cellularity of fusion masses when comparing the autograft and osteogenic protein-1 specimens. CONCLUSIONS: No model before this exists that tests the efficacy of bone morphogenic proteins in as challenging an environment. Extrapolation of single-level preclinical and clinical studies with bone morphogenic proteins for use in multilevel fusion requires careful review. Autograft and osteogenic protein-1 had similar rates of fusion. A high rate of nonunion is seen with this multiple level fusion to the sacrum using autograft or osteogenic protein-1. The biologic enhancement with osteogenic protein-1 is not able to overcome this mechanically rigorous model.