Double row equivalent for rotator cuff repair: A biomechanical analysis of a new technique.

INTRODUCTION: There are numerous configurations of double row fixation for rotator cuff tears however, there remains to be a consensus on the best method. In this study, we evaluated three different double-row configurations, including a new method. Our primary question is whether the new anchor and technique compares in biomechanical strength to standard double row techniques. METHODS: Eighteen prepared fresh frozen bovine infraspinatus tendons were randomized to one of three groups including the New Double Row Equivalent, Arthrex Speedbridge and a transosseous equivalent using standard Stabilynx anchors. Biomechanical testing was performed on humeri sawbones and ultimate load, strain, yield strength, contact area, contact pressure, and a survival plots were evaluated. RESULTS: The new double row equivalent method demonstrated increased survival as well as ultimate strength at 415N compared to the remainder testing groups as well as equivalent contact area and pressure to standard double row techniques. CONCLUSIONS: This new anchor system and technique demonstrated higher survival rates and loads to failure than standard double row techniques. This data provides us with a new method of rotator cuff fixation which should be further evaluated in the clinical setting. LEVEL OF EVIDENCE: Basic science biomechanical study.

Costs and Complications of Short Versus Long Cephalomedullary Nailing of OTA 31-A2 Proximal Femur Fractures in U.S. Veterans.

OBJECTIVES: In fractures without subtrochanteric extension, the indications for the use of short versus long cephalomedullary nails (CMNs) for intertrochanteric femur fractures are unclear. We hypothesized that long nails would be associated with higher costs and similar complication rates. DESIGN: Retrospective comparative study. SETTING: United States Department of Veterans Affairs Medical Centers. PARTICIPANTS: Patients receiving CMNs for OTA 31-A2 pertrochanteric fractures from 2001 to 2010. INTERVENTIONS: Short versus long cephalomedullary nailing. MAIN OUTCOME MEASUREMENTS: Costs, perioperative complications, readmissions, surgical failures, and mortality. RESULTS: We identified 262 patients with OTA 31-A2 pertrochanteric fractures (125 treated with short CMNs and 137 treated with long CMNs). The 2 cohorts had similar demographic and medical characteristics. There were no significant differences in perioperative complications, readmissions within 30 days, surgical failures within one year, or death within 30 days or one year. The average cost of hospitalization was significantly higher for the cohort treated with long nails (greater than $7000 in actual costs, and greater than $3000 when statistically adjusted for differences in postoperative lengths of stay). Multivariable analyses showed no significant differences in the rates of development of at least one complication, readmission, or death. CONCLUSIONS: In a cohort of patients with similar characteristics and fracture patterns, the use of long CMNs was associated with similar rates of complications, readmission, and reoperations, but significantly higher costs than with the use of short nails. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Hierarchical analysis and multi-scale modelling of rat cortical and trabecular bone.

The aim of this study was to explore the hierarchical arrangement of structural properties in cortical and trabecular bone and to determine a mathematical model that accurately predicts the tissue's mechanical properties as a function of these indices. By using a variety of analytical techniques, we were able to characterize the structural and compositional properties of cortical and trabecular bones, as well as to determine the suitable mathematical model to predict the tissue's mechanical properties using a continuum micromechanics approach. Our hierarchical analysis demonstrated that the differences between cortical and trabecular bone reside mainly at the micro- and ultrastructural levels. By gaining a better appreciation of the similarities and differences between the two bone types, we would be able to provide a better assessment and understanding of their individual roles, as well as their contribution to bone health overall.