Recent work with Saccharomyces cerevisiae shows a linear relationship between the evolutionary rate of sites and the relative solvent accessibility (RSA) of the corresponding residues in the folded protein. Here, we aim to develop a mathematical model that can reproduce this linear relationship. We first demonstrate that two models that both seem reasonable choices (a simple model in which selection strength correlates with RSA and a more complex model based on RSA-dependent amino acid distributions) fail to reproduce the observed relationship. We then develop a model on the basis of observed site-specific amino acid distributions and show that this model behaves appropriately. We conclude that evolutionary rates are directly linked to the distribution of amino acids at individual sites. Because of this link, any future insight into the biophysical mechanisms that determine amino acid distributions will improve our understanding of evolutionary rates.

Objectives: To evaluate the cost effectiveness of suture buttons compared with syndesmotic screws for repair of tibiofibular syndesmotic injuries. Methods: A decision tree model was constructed to describe outcomes after syndesmosis repair using suture buttons and syndesmotic screws from the perspective of a capitated health care system. Outcomes were uneventful healing, removal of symptomatic implants, deep infection, and persistent diastasis requiring revision. Weighted literature averages were used to estimate variables for a baseline model. Outcomes were measured in quality adjusted life years. Procedure and implant costs were derived from Medicare reimbursement rates and the University Health System Consortium. An incremental cost-effectiveness ratio threshold of $50,000 per quality-adjusted life years was used to evaluate cost effectiveness. Results: The baseline model did not identify suture buttons to be cost effective. Sensitivity analysis demonstrates the model to be exquisitely sensitive to small changes in reoperation rates and implant price. At median University Health System Consortium implant prices, if the removal rate for symptomatic screws is below 13.7%, then screws are cost effective. If the screw removal rate is greater than 17.5%, then a suture button is cost effective. Within this interval, detailed analysis of the model suggests that screws may be the cost-effective strategy, but that determination should be taken with caution. Conclusions: Moving away from the practice of routinely removing all syndesmotic screws has changed the financial landscape of syndesmosis repair. At their median cost, suture buttons are likely to be cost effective over screws for symptomatic screw removal rates greater than 17.5%. Cost effectiveness is sensitive to changes in implant removal rates and the number of devices used per patient. Level of Evidence: Economic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Background: Neer type-II distal clavicle fractures are unstable and are generally appropriately managed with operative fixation. Fixation options include locking plates, hook plates, and suture button devices. No consensus on optimal technique exists. Methods: A decision tree model was created describing fixation of Neer type-II fractures using hook plates, locking plates, or suture buttons. Outcomes included uneventful healing, symptomatic implant removal, deep infection requiring debridement, and nonunion requiring revision. Weighted averages derived from a systematic review were used for probabilities. Cost-effectiveness was evaluated by calculating incremental cost-effectiveness ratios (ICERs). The ICER is defined as the ratio of the difference in cost and difference in effectiveness of each strategy, and is measured in cost per quality-adjusted life year (QALY). The model was evaluated using thresholds of $50,000/QALY and $100,000/QALY. Sensitivity analysis was performed on all outcome probabilities for each fixation strategy to assess cost-effectiveness across a range of values. Results: Forty-three papers met final inclusion criteria. Using suture buttons as the reference case in the health-care cost model, suture button repair was dominant (both less expensive and clinically superior). Hook plates cost substantially more ($5,360.52) compared with suture buttons and locking plates ($3,713.50 and $4,007.44, respectively). Suture buttons and locking plates yielded similar clinical outcomes (0.92 and 0.91 QALY, respectively). Suture button dominance persisted in the societal perspective model. Sensitivity analysis on outcome probabilities showed that locking plates became the most cost-effective strategy if the revision rate after their use was lowered to 2.2%, from the overall average in the sources of >19%. No other changes in outcome probabilities for any of the 3 techniques allowed suture buttons to be surpassed as the most cost-effective. Conclusions: The cost-effectiveness of suture buttons is driven by low revision rates and high uneventful healing rates. Similar QALY values for locking plate and suture button fixation were observed, which is consistent with existing literature that has failed to identify either as the clinically superior technique. Cost-effectiveness should fit prominently into the decision-making rubric for these injuries. Level of Evidence: Economic Level IV. See Instructions for Authors for a complete description of levels of evidence.

➤ A transgender person is defined as one whose gender identity is incongruent with their biological sex assigned at birth. This highly marginalized population numbers over 1.4 million individuals in the U.S.; this prevalence skews more heavily toward younger generations and is expected to increase considerably in the future. ➤ Gender-affirming hormone therapy (GAHT) has physiologic effects on numerous aspects of the patient’s health that are pertinent to the orthopaedic surgeon, including bone health, fracture risk, and perioperative risks such as venous thromboembolism and infection. ➤ Language and accurate pronoun usage toward transgender patients can have a profound effect on a patient’s experience and on both objective and subjective outcomes. ➤ Gaps in research concerning orthopaedic care of the transgender patient are substantial. Specific areas for further study include the effects of GAHT on fracture risk and healing, outcome disparities and care access across multiple subspecialties, and establishment of perioperative management guidelines.

Background: Stiffness and pain from arthrofibrosis following total knee arthroplasty (TKA) is a challenging problem, and investigating methods to prevent or reduce the incidence of postoperative arthrofibrosis is critical. Studies have shown that angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) are efficacious at preventing fibrotic disorders in the lungs, liver, kidneys, and eyes. Our aim was to determine if ACEI or ARB use postoperatively reduces the incidence of arthrofibrosis in TKA patients. Methods: In a retrospective review, we analyzed 141 consecutive TKAs performed at a single institution by a single surgeon from December 2010 to December 2014. Range of motion (ROM) in patients already taking ACEI, ARB, or neither medication was compared. Independent variables recorded were gender, age, BMI, presence of diabetes or preoperative opioid or statin use, preoperative ROM, and use of ACEIs or ARBs. Dependent variables recorded were postoperative knee flexion, extension, and total arc of motion. The primary outcome variable was success or failure of achieving 118^o total arc of motion postoperatively, based on a study that found significant compromise of function in TKA patients who failed to obtain this goal. Secondary endpoints were postoperative knee flexion, extension, and total arc of motion. Results: The use of neither ACEIs nor ARBs showed a significant difference in attaining greater than 118° of motion postoperatively compared to controls at 6 months. Significant predictors of obtaining > 118° motion were BMI (p < 0.05), preoperative flexion (p < 0.001), and preoperative total arc of motion (p < 0.002). Significant predictors of secondary ROM outcomes were preoperative ROM and BMI. Conclusions: Our study demonstrated that the principle predictor of postoperative ROM is BMI and preoperative ROM. The use of ACEIs or ARBs did not result in a greater likelihood of obtaining satisfactory ROM postoperatively.

Olecranon osteotomy is a commonly used method for obtaining adequate exposure of the articular surface in complex distal humeral fractures. We describe a new technique whereby a precontoured olecranon plate is first fixed to the olecranon, and a Gigli saw is used to perform the osteotomy while the plate is in place. By use of a standard posterior approach, a precontoured olecranon plate is applied to the olecranon and affixed with screws both proximally and distally to the planned osteotomy site. A Gigli saw is passed anterior to the olecranon and is used to create an osteotomy through the bare area of the sigmoid notch. The plate is removed from the distal fragment. The proximal olecranon fragment, plate, and extensor mechanism are retracted proximally en bloc to expose the articular surface. After fracture repair, the osteotomy fragments are reapproximated, and the plate is reattached to the distal fragment. QuickDASH (short version of the Disabilities of the Arm, Shoulder and Hand questionnaire) and Veterans RAND 12-Item Health Survey (VR-12) scores for patients treated with this technique were compared with those of patients treated with the standard chevron osteotomy method. All patients achieved radiographic and clinical union of the osteotomy site. QuickDASH, VR-12 physical, and VR-12 mental scores were not significantly different from those of patients in the chevron osteotomy group (P = .93, P = .79, and P = .68, respectively; t test). The described method provides excellent visualization of the joint, is less technically challenging than the standard chevron osteotomy, and reduces operative time. Osteotomy union was attained in all 5 cases, with functional outcomes comparable with those attained with the chevron technique.