The load transfer effect of monopolar and bipolar radial head prosthesis designs on capitellar cartilage: A comparative biomechanical cadaver study.

OBJECTIVE: The aim of this study was to determine whether bipolar radial head arthroplasty may transfer less load to the capitellum than monopolar radial head arthroplasty and native radial heads. METHODS: Six human elbow joints were obtained from six fresh frozen cadavers (3 males, 3 females; mean age = 78 years, age range = 66-80). None of the elbow joints had a previous osseous injury, a chondral defect, osteoarthritis, or instability. In group 1, load transfer of the native radial head was measured in each specimen under 100 N of compression force using a custom-made load cell at 0°, 30°, 60°, 90°, and 120° flexion of the elbow in supination, neutral rotation, and pronation, respectively. After excision of the radial heads, the same testing protocol was first applied for monopolar radial head arthroplasty (Group 2) and then for bipolar radial head arthroplasty (Group 3). RESULTS: The mean load transfer on the capitellum was significantly higher in each forearm rotation and all angles of the elbow flexion in the arthroplasty groups than the native radial head group. Mean load transfer values of bipolar prostheses were between the values of native radial heads and monopolar prostheses in all positions. Bipolar prostheses showed similar load transfer characteristics compared to those of the native radial head in supination at 60° flexion; in neutral rotation at 0°, 30°, 60°, and 120° flexion; and in pronation at 90° and 120° flexion. CONCLUSION: The results of this study have revealed that bipolar radial head arthroplasty transfers similar loading as the native radial head on the capitellum in certain forearm positions and at elbow flexion angles. No significant differences could be found between load transfer values of bipolar head design and monopolar head design except in the pronation at full extension.

Standard and Newly Defined Prognostic Factors Affecting Early Mortality After Hip Fractures.

PURPOSE: Early mortality rate in geriatric patients after hip fractures remains very high. Determining the prognostic factors is crucial for decreasing early mortality. This study aimed to evaluate the prognostic risk factors affecting early mortality after hip fracture in the elderly. METHODS: Medical records of 335 patients with age 70 years or older who sustained hip fractures which were treated by hemiarthroplasty or proximal femoral nailing between May 2017 and May 2019 were reviewed. Neutrophil/lymphocyte ratio (NLR) and platelet/lymphocyte ratio (PLR) were investigated for validity as the new prognostic markers. The other variables included age, gender, type of surgery, type of implant, type of anesthesia, American Society of Anesthesiologists (ASA) score, presence of comorbidities, delirium, length of hospital stay, time delay to surgery, number of erythrocyte transfusions, and laboratory data were assessed for 30-day, 90-day, and one-year mortality. Univariate analysis and logistic regression analysis were used to determine the associated mortality. RESULTS: Thirty-day mortality rate was 10.4% and was associated with being aged ≥90 years (p-value: 0.013, odds ratio {OR}: 0.13) and ASA score of 4 (p-value: 0.019, OR: 0.22). Ninety-day mortality rate was 21.5% and was associated with age (p-value: 0.002), being aged 80-89 years (p-value: 0.032, OR: 0.43), being aged ≥90 years (p-value: 0.001, OR: 0.13), general anesthesia (p-value: 0.016, OR: 0.41), preoperative high NLR level (p-value: 0.028, OR: 1.05), high blood urea nitrogen (BUN) level (p-value: 0.049, OR:1.02). One year mortality rate was 33.7% and independent significant prognostic risk factors were determined as being aged ≥90 years (p-value: 0.003, OR: 0.23), length of hospital stay (p-value: 0.003, OR: 1.04), and preoperative serum albumin level (p-value: 0.037, OR: 0.6). The other evaluated risk factors were not independently found to be associated with all early mortality time. CONCLUSION: Patients at or over 90 years old were at risk for all early mortality time points. NLR which is a new and cheap biomarker can be used as a prognostic risk factor for 90-day mortality. The variable of PLR was not found valuable for early mortality.