Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures

Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo

Biomechanical Comparison of Hybrid Versus Non Locking Screw Fixation for Midshaft Clavicle Fractures

Objectives: Recent studies report nonunion rates of up to fifteen percent for nonoperative treatment of displaced, comminuted, or shortened midshaft clavicle fractures. Additionally, authors suggest operative treatment of these comminuted displaced midshaft clavicle fractures leads to a more satisfactory clinical outcome. Biomechanically, clavicle fracture plate fixation has been analyzed for locking versus non-locking screw use, but little evidence on hybrid screw use exists. We hypothesized that fixation of a comminuted midshaft clavicle fracture model with a pre-contoured hybrid screw-plate construct would increase stiffness and load-to-failure compared to a non-locking screw construct. Methods: Fourteen matched pairs of fresh frozen cadaveric clavicles were randomized into two groups: hybrid screw fixation (n=7 pairs) and non-locking screw fixation (n=7 pairs). One clavicle from each pair was randomly selected to receive a 1cm midshaft gap osteotomy and plate fixation, while the remaining clavicle was tested as the intact control. The clavicles were tested through four-point bending to determine stiffness and load-to-failure. Results: The hybrid construct was seventeen percent more stiff compared to the non-locked construct, although this did not reach statistical significance (p=0.09). The non-locked construct was significantly less stiff than the intact clavicle, whereas there was no significant difference in stiffness between the hybrid construct and the intact clavicle. Load-to-failure was not significantly different between the hybrid and nonlocked constructs. Conclusion: There was a trend towards higher stiffness of the hybrid construct compared to the non-locked construct. A similar study with more statistical power is needed to fully elicit the true differences in stiffness and load-to-failure between the two constructs. Level of Evidence: Basic Science Study – Biomechanical Level

Biomechanical Comparison of Hybrid Versus Non Locking Screw Fixation for Midshaft Clavicle Fractures

Objectives: Recent studies report nonunion rates of up to fifteen percent for nonoperative treatment of displaced, comminuted, or shortened midshaft clavicle fractures. Additionally, authors suggest operative treatment of these comminuted displaced midshaft clavicle fractures leads to a more satisfactory clinical outcome. Biomechanically, clavicle fracture plate fixation has been analyzed for locking versus non-locking screw use, but little evidence on hybrid screw use exists. We hypothesized that fixation of a comminuted midshaft clavicle fracture model with a pre-contoured hybrid screw-plate construct would increase stiffness and load-to-failure compared to a non-locking screw construct. Methods: Fourteen matched pairs of fresh frozen cadaveric clavicles were randomized into two groups: hybrid screw fixation (n=7 pairs) and non-locking screw fixation (n=7 pairs). One clavicle from each pair was randomly selected to receive a 1cm midshaft gap osteotomy and plate fixation, while the remaining clavicle was tested as the intact control. The clavicles were tested through four-point bending to determine stiffness and load-to-failure. Results: The hybrid construct was seventeen percent more stiff compared to the non-locked construct, although this did not reach statistical significance (p=0.09). The non-locked construct was significantly less stiff than the intact clavicle, whereas there was no significant difference in stiffness between the hybrid construct and the intact clavicle. Load-to-failure was not significantly different between the hybrid and nonlocked constructs. Conclusion: There was a trend towards higher stiffness of the hybrid construct compared to the non-locked construct. A similar study with more statistical power is needed to fully elicit the true differences in stiffness and load-to-failure between the two constructs. Level of Evidence: Basic Science Study – Biomechanical Level

Biomechanical Comparison of Hybrid Versus Non Locking Screw Fixation for Midshaft Clavicle Fractures

Objectives: Recent studies report nonunion rates of up to fifteen percent for nonoperative treatment of displaced, comminuted, or shortened midshaft clavicle fractures. Additionally, authors suggest operative treatment of these comminuted displaced midshaft clavicle fractures leads to a more satisfactory clinical outcome. Biomechanically, clavicle fracture plate fixation has been analyzed for locking versus non-locking screw use, but little evidence on hybrid screw use exists. We hypothesized that fixation of a comminuted midshaft clavicle fracture model with a pre-contoured hybrid screw-plate construct would increase stiffness and load-to-failure compared to a non-locking screw construct. Methods: Fourteen matched pairs of fresh frozen cadaveric clavicles were randomized into two groups: hybrid screw fixation (n=7 pairs) and non-locking screw fixation (n=7 pairs). One clavicle from each pair was randomly selected to receive a 1cm midshaft gap osteotomy and plate fixation, while the remaining clavicle was tested as the intact control. The clavicles were tested through four-point bending to determine stiffness and load-to-failure. Results: The hybrid construct was seventeen percent more stiff compared to the non-locked construct, although this did not reach statistical significance (p=0.09). The non-locked construct was significantly less stiff than the intact clavicle, whereas there was no significant difference in stiffness between the hybrid construct and the intact clavicle. Load-to-failure was not significantly different between the hybrid and nonlocked constructs. Conclusion: There was a trend towards higher stiffness of the hybrid construct compared to the non-locked construct. A similar study with more statistical power is needed to fully elicit the true differences in stiffness and load-to-failure between the two constructs. Level of Evidence: Basic Science Study – Biomechanical Level

Rabbit Supraspinatus Motor Endplates Are Unaffected by a Rotator Cuff Tear

Rotator cuff tears are a major cause of morbidity. Following rotator cuff tears, muscle atrophy and fatty infiltration begin in the tissue, limiting repair potential and leading to a higher re-tear rate and a worse functional outcome. We evaluated whether fatty degeneration resulting from a complete supraspinatus tear with retraction is associated with an injury to the suprascapular nerve. Four skeletally mature New Zealand white rabbits were randomized to receive an index procedure on either their right or left shoulder with the opposite shoulder serving as a control. At the index procedure, the supraspinatus tendon was transected at its insertion and allowed to retract. At 3 months, the rabbits were euthanized, and both supraspinatus muscles were harvested. The specimens were then examined with confocal microscopy and histology. Atrophy was grossly visible in all four test muscles, and fatty infiltration was confirmed with osmium tetroxide staining. In all four rabbits, the degree of denervation (p = 0.71) and partial denervation (p = 0.91) was not significantly different between control and experimental muscle. Rotator cuff tear does not affect the motor endplate or innervation status of the supraspinatus. Fatty infiltration occurs independent of denervation of the supraspinatus. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31:99–104, 201

Rabbit Supraspinatus Motor Endplates Are Unaffected by a Rotator Cuff Tear

Rotator cuff tears are a major cause of morbidity. Following rotator cuff tears, muscle atrophy and fatty infiltration begin in the tissue, limiting repair potential and leading to a higher re-tear rate and a worse functional outcome. We evaluated whether fatty degeneration resulting from a complete supraspinatus tear with retraction is associated with an injury to the suprascapular nerve. Four skeletally mature New Zealand white rabbits were randomized to receive an index procedure on either their right or left shoulder with the opposite shoulder serving as a control. At the index procedure, the supraspinatus tendon was transected at its insertion and allowed to retract. At 3 months, the rabbits were euthanized, and both supraspinatus muscles were harvested. The specimens were then examined with confocal microscopy and histology. Atrophy was grossly visible in all four test muscles, and fatty infiltration was confirmed with osmium tetroxide staining. In all four rabbits, the degree of denervation (p = 0.71) and partial denervation (p = 0.91) was not significantly different between control and experimental muscle. Rotator cuff tear does not affect the motor endplate or innervation status of the supraspinatus. Fatty infiltration occurs independent of denervation of the supraspinatus. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31:99–104, 201