Biomechanical analysis of peri­implant fractures in short versus long cephalomedullary implants following pertrochanteric fracture consolidation.

INTRODUCTION: Pertrochanteric femur fracture fixation with use of cephalomedullary nails (CMN) has become increasingly popular in recent past. Known complications after fracture consolidation include peri­implant fractures following the use of both short and long nails, with fracture lines around the tip of the nail or through the interlocking screw holes, resulting in secondary midshaft or supracondylar femur fractures, respectively. Limited research exists to help the surgeon decide on the use of short versus long nails, while both have their benefits. The aim of this biomechanical study is to investigate in direct comparison one of the newest generations short and long CMNs in a human anatomical model, in terms of construct stability and generation of secondary fracture pattern following pertrochanteric fracture consolidation. METHODS: Eight intact human anatomical femur pairs were assigned to two groups of eight specimens each for nailing using short or long CMNs. Each specimen was first biomechanically preloaded at 1 Hz over 2000 cycles in superimposed synchronous axial compression to 1800 N and internal rotation to 11.5 Nm. Following, internal rotation to failure was applied over an arc of 90° within one second under 700 N axial load. Torsional stiffness as well as torque at failure, angle at failure, and energy to failure were evaluated. Fracture patterns were analyzed. RESULTS: Outcomes in the study groups with short and long nails were 9.7 ± 2.4 Nm/° and 10.2 ± 2.9 Nm/° for torsional stiffness, 119.8 ± 37.2 Nm and 128±46.7 Nm for torque at failure, 13.5 ± 3.5° and 13.4 ± 2.6° for angle at failure, and 887.5 ± 416.9 Nm° and 928.3 ± 461.0 Nm° for energy to failure, respectively, with no significant differences between them, p ≥ 0.17. Fractures through the distal locking screw holes occurred in 5 and 6 femora instrumented with short and long nails, respectively. Fractures through the lateral entry site of the head element were detected in 3 specimens within each group. For short nails, fractures through the distal shaft region, not interfacing with the implant, were detected in 3 specimens. CONCLUSION: From a biomechanical perspective, the risk of secondary peri­implant fracture after intramedullary fixation of pertrochanteric fractures is similar when using short or long CMN. Moreover, for both nail versions the fracture pattern does not unexceptionally involve the distal locking screw hole.

Fracture of the Neck of a Lateral Flare Femoral Implant in Total Hip Arthroplasty.

We present the case of a 38-year-old man who presented 7 years after primary total hip replacement with a fracture of the neck of a lateral flare femoral stem and catastrophic polyethylene wear. The unique design of the lateral flare hip stem has been shown previously to be associated with accelerated polyethylene wear, whereas the stem remains well fixed. The resultant polyethylene wear results in the harder cobalt chrome head abrading the titanium shell generating metallic debris. This may have resulted in proximal migration of the implant neck into the cup with subsequent neck-cup impingement and implant fracture.

The impact of solid organ transplant history on inpatient complications, mortality, length of stay, and cost for primary total shoulder arthroplasty admissions in the United States.

BACKGROUND: There is a growing population of patients with history of solid organ transplant (SOT) surgery among total joint patients. Patients with history of SOT have been found to have longer lengths of stay and higher inpatient hospital costs and complications rates after hip and knee arthroplasty. The purpose of this study was to determine whether this is true for shoulder arthroplasty in SOT patients. METHODS: The Nationwide Inpatient Sample was queried to describe relative demographic, hospital, and clinical characteristics, perioperative complications, length of stay, and total costs for patients with a history of SOT (International Classification of Diseases-9th Edition-Clinical Modificiation V42.0, V42.1, V42.7, V42.83) undergoing shoulder arthroplasty (81.80, 81.88) from 2004 to 2014. RESULTS: A weighted total of 843 patients (unweighted frequency = 171) and 382,773 patients (unweighted frequency = 77,534) with and without history of SOT, respectively, underwent shoulder arthroplasty. SOT patients were more often younger and more likely to be male, have Medicare, and undergo surgery in a large teaching institution in the Midwest or Northeast (P < .001). SOT patients had higher or similar comorbid disease prevalence for 27 of 29 Elixhauser comorbidities. The risk of any complication was significantly higher among SOT patients (15.5% vs. 9.3%, P = .007). SOT patients experienced inpatient admissions an average 0.27 days longer (P < .001) and $1103 more costly (P = .06) than non-SOT patients. CONCLUSIONS: Patients with history of SOT undergoing shoulder arthroplasty appear to remain a unique population due to their specific vulnerability to minor complications and inherently increased inpatient resource utilization.