Cass, Joseph R.

AbstractPeriprosthetic fractures around a total knee arthroplasty (TKA), comminuted and intra-articular femur fractures, or fracture nonunions in osteoporotic bone represent technically challenging problems. This is particularly true when the fracture involves a loose femoral component or the pattern results in suboptimal fixation potential. These clinical indications often arise in an older and comorbid patient population in whom a principal goal of treatment includes allowing for early mobilization. Limited data indicate that arthroplasty via distal femoral replacement (DFR) is a reasonable alternative to open reduction and internal fixation, allowing for early ambulation with low complication rates. We performed a retrospective review of trauma and arthroplasty surgeries at three tertiary referral institutions. Adult patients treated for the above with a DFR were included. Patients with active infection, open and/or high-energy injuries and revisions unrelated to fracture were excluded. Patient demographics, treatment details, and outcomes were assessed. Between 2002 and 2017, 90 DFR's were performed for the above indications with a mean follow-up of 24 months. Postoperatively, 80 patients (88%) were allowed to weight bear as tolerated, and at final follow-up, 9 patients (10%) remained dependent on a wheelchair. The average arc of motion at final follow-up was 95 degrees. There were seven (8%) implant-related complications requiring secondary surgeries: two infections, one with associated component loosening; one fracture of the hinge mechanism and one femoral component failure in conjunction with a patellofemoral dislocation (both requiring revision); one case of patellofemoral arthrosis in a patient with an unresurfaced patella; one periprosthetic fracture with associated wound dehiscence; and one case of arthrofibrosis. In each of these cases, only modular components of the DFR were exchanged. All nonmodular components cemented into the femur or tibia were retained. DFR provides a viable reconstruction option in the treatment of acute distal femur fractures, periprosthetic femur fractures, and fracture nonunions. We noted that in an elderly patient population with high comorbidities, the complication and secondary surgery rates remained relatively low, while allowing for immediate weight bearing.

Objectives: To determine whether fixation of pertrochanteric hip fractures with cephalomedullary nails (CMNs) with a neck-shaft angle (NSA) less than the native NSA affects reduction and lag screw cutout. Design: Retrospective comparative study. Setting: Level I trauma center. Patients/Participants: Patients treated with a CMN for unstable pertrochanteric femur fractures (OTA/AO 31-A2.2 and 31-A2.3) between 2005 and 2014. Intervention: CMN fixation. Main Outcome Measurement: NSA reduction and lag screw cutout. Results: Patients fixed with a nail angle less than their native NSA were less likely to have good reductions [17% vs. 60%, 95% confidence interval (CI), −63% to −18%; P = 0.0005], secondary to more varus reductions (41% vs. 10%, 95% CI, 9%–46%; P = 0.01) and more fractures with ≥4 mm of displacement (63% vs. 35%, 95% CI, 3%–49%; P = 0.03). The cutout was not associated with the use of a nail angle less than the native NSA (60% vs. 76%, 95% CI, −56% to 18%; P = 0.5), varus reductions (60% vs. 32%, 95% CI, −13% to 62%; P = 0.3), or poor reductions (20% vs. 17%, 95% CI, −24% to 44%; P = 1.0). Conclusions: The fixation of unstable pertrochanteric hip fractures with a nail angle less than the native NSA was associated with more varus reductions and fracture displacement but did not affect the lag screw cutout. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Case: We report two cases of modular head-neck junction failure involving the Stryker Accolade TMZF stem leading to sudden dissociation of the femoral head from the stem. Both patients presented with mechanical symptoms in the hip followed by pain and hip dysfunction. Disassembly of the head and deformation of the male taper were seen on preoperative radiographs. Intraoperatively, both patients had substantial metallosis with a markedly damaged taper requiring stem revision. Conclusion: We recommend regular clinical and radiographic surveillance of patients with the Stryker Accolade TMZF stem, especially those patients with pain and/or mechanical symptoms.

ABSTRACTA 75-year-old man was diagnosed with probableCampylobacter jejuniprosthetic knee infection after a diarrheal illness. Joint aspirate and operative cultures were negative, but PCR of prosthesis sonicate fluid was positive, as was stool culture. Nineteen additional cases ofCampylobacterprosthetic joint infection reported in the literature are reviewed.

Background Cam-type femoral impingement is caused by structural abnormalities of the hip and is recognized as a cause of degenerative hip arthritis. Identifiable etiologies of this structural abnormality include congenital malformation, pediatric hip disease, and malunion of femoral neck fractures after internal fixation. Purpose The purpose of this study was to determine the prevalence of radiographic impingement in healed Orthopaedic Trauma Association (OTA) type 31B fractures treated with reduction and internal fixation. Methods Seventy OTA 31B hip fractures treated with internal fixation were identified from our institutional trauma database and radiographs were retrospectively reviewed for signs of impingement. Mean follow-up was 53 months after fracture. Alpha angle, Mose templates, and femoral head retroversion were the measurements used to determine impingement. Results The overall prevalence of any sign of radiographic impingement was 75%. Alpha angle was elevated in 32 hips (46%), asphericity was present in 46 femoral heads (65%), and femoral head retroversion was present in 26 hips (37%). The rates were highest in displaced subcapital fractures (OTA 31B-3) with a 63% (13/19) prevalence of elevated alpha angle, 68% (14/19) prevalence of asphericity, and 47% (10/19) prevalence of retroversion. Conclusions Prevalence of radiographic signs of impingement in this population is higher than expected based on population-based controls. Surgeons must be vigilant about reduction and fixation of femoral neck fractures. Malunion should be recognized as early intervention may be beneficial in improving long-term outcomes.

The stabilizing capacity of the ligaments and articular surface in the ankle was determined under defined physiologic loading conditions. The concept of primary and secondary constraints was adapted to the ankle. With physiologic loading, the articular surface ac counted for 30% and 100% of stability in rotation and version, respectively. That the articular surface was the sole source of inversion and eversion stability under the prescribed physiologic loading conditions has not been previously reported. The demonstration that the articular surface resists inversion displacement in the loaded ankle supports the conclusion of previous studies that rotation, rather than inversion, may account for a type of clinically sympto matic ankle instability. Further, ankle instability may occur during loading and unloading but not once the ankle is fully loaded. The results of our study confirm the importance of the anterior talofibular and calcaneo fibular ligaments and suggest an important role for the deltoid ligament.