Relationship of bicipital groove rotation with humeral head retroversion: a three-dimensional computed tomographic analysis.

BACKGROUND: Bicipital groove location has been used as a reference for humeral stem orientation in total shoulder arthroplasty to recreate humeral head retroversion. However, anatomic variability has rendered its use for prosthetic orientation problematic in cases of comminuted proximal fractures. We hypothesized that variability in groove rotation is directly related to variability in humeral head retroversion and that by defining the degree of groove rotation, humeral head retroversion can be predicted. METHODS: Computed tomographic scans (1-mm sections) were obtained along the entire lengths of thirty-four cadaveric humeri, and three-dimensional models were created by using computer-assisted design software. Humeral head retroversion was determined in reference to the transepicondylar axis. The bicipital groove was mapped from proximal to distal, and the rotation of the groove in relationship to the transepicondylar axis was tracked over the entire length of the groove. The overall groove rotation and the rotation of its proximal, intermediate, and distal 15-mm segments were determined. RESULTS: The average humeral head retroversion was 21°, and the average angles of groove rotation in relation to the transepicondylar axis for the overall groove and the proximal, intermediate, and distal segments were 65°, 60°, 63°, and 71° of internal rotation relative to the transepicondylar axis, respectively. Pearson correlation coefficients between bicipital groove rotation and humeral head retroversion were ≥0.78 for all segments. CONCLUSIONS: A previously unknown direct correlation between bicipital groove rotation and humeral head retroversion was found to exist. The ability to predict humeral head retroversion when mapping only the distal third of the groove has potentially important clinical implications because the distal third is often the only portion of the groove remaining in patients with a comminuted proximal humeral fracture. This is particularly relevant with computer-navigated surgery.

Arthroscopically assisted percutaneous fixation of Bennett fractures.

Arthroscopic-assisted reduction and fixation of Bennett-type fractures of the thumb metacarpal allow for the confirmation of reduction as well as the assessment of the degree of chondral damage. With use of a 1.9-mm arthroscope and a traction tower, direct visualization and reduction is possible. Traditional methods of fixation are used to secure the fracture fragment. Postoperative rehabilitation follows the usual protocol used in both open and percutaneous techniques. However, the potential to obtain and confirm a more accurate articular reduction may reduce the incidence of late arthritis of the thumb carpometacarpal articulation.

Determining the statistical significance of relative weights.

Relative weight analysis is a procedure for estimating the relative importance of correlated predictors in a regression equation. Because the sampling distribution of relative weights is unknown, researchers using relative weight analysis are unable to make judgments regarding the statistical significance of the relative weights. J. W. Johnson (2004) presented a bootstrapping methodology to compute standard errors for relative weights, but this procedure cannot be used to determine whether a relative weight is significantly different from zero. This article presents a bootstrapping procedure that allows one to determine the statistical significance of a relative weight. The authors conducted a Monte Carlo study to explore the Type I error, power, and bias associated with their proposed technique. They illustrate this approach here by applying the procedure to published data.

Acute ulnar collateral ligament injury in the athlete.

The functional thumb is a necessity for successful athletic participation. It not only allows the athlete to manipulate athletic equipment but also allows the precise manipulation of objects in the athlete's hand. Injury to the thumb often negates power grip and finesse of the athletic hand. Injuries can range from fractures, to dislocations, to ligamentous injuries. The relatively unconstrained thumb metacarpophalangeal joint is particularly vulnerable to injury from an abduction moment to its distal segment. Such injuries occur from direct contact and with falls on equipment such as racquet handles and ski poles. The stability of the athlete's metacarpophalangeal joint must be restored to allow for a productive return to sport.

Brodie's abscess of the distal radius: an unusual complication after percutaneous pinning.

We report a case of Brodie's abscess of the distal radius that presented 4 years after closed reduction and percutaneous pinning for a closed distal radius fracture. This condition has not been previously reported in the adult distal radius and we detail the clinical features and imaging findings. We also present a new way of management of Brodie's abscess using injectable bone substitute along with adjunctive parenteral antibiotic therapy.

The influence of educational preparation on evaluations of applicants for radiation therapy positions: a policy-capturing experiment.

PURPOSE: To determine whether radiation therapy department administrators prefer to hire graduates with certain types of educational preparation. The study was undertaken by the American Registry of Radiologic Technologists as part of a larger project to determine educational requirements for radiation therapists. METHODS AND MATERIALS: Forty-one department administrators evaluated applications from a pool of 984 hypothetical applicants for the position of radiation therapist. Applications were created by systematically varying eight characteristics such as years of experience, quality of educational program, and ratings from prior references. Type of educational program (baccalaureate degree, associate's degree, or hospital certificate) was of particular interest in this study. Each administrator evaluated 24 applications and assigned a rating ranging from 1 to 5 to indicate the extent to which he or she desired to interview each applicant. All ratings and applicant characteristics were coded and subjected to regression-type analyses to determine the relative importance of each applicant characteristic to administrators' decision-making policies. RESULTS: Information obtained from applicant references had the greatest impact on administrators' evaluations of applicant quality. Specifically, reference ratings of cooperation and technical skills were the two most important characteristics, followed closely by reference ratings of interpersonal skills and dependability. Quality of educational program had some influence, as did years of experience. Type of educational program had virtually no impact on interview decisions for a vast majority of the administrators. CONCLUSIONS: When making hiring decisions about hypothetical applicants, department administrators place most emphasis on evidence relating to past performance and give almost no weight to type of educational preparation. The extent to which these results generalize to actual applicants is addressed in the article.