Variations in Hook of Hamate Morphology: A Cadaveric Analysis.

PURPOSE: The hook of the hamate is an anatomical structure that separates the ulnar border of the carpal tunnel from Guyon's canal and serves as a landmark for surgeons. The hook of the hamate is also subject to fracture from injury. We hypothesize that there are variations in the hook of the hamate in the general population. METHODS: One thousand pairs of hamates (2,000 hamates) from the Hamann-Todd Collection at the Cleveland Natural History Museum were analyzed. The height of the hook of the hamate and the total height of the hamate bone were measured using digital calipers. The hook height ratio was defined as the hook height divided by the total height of the hamate. Statistical analysis was performed using unpaired Student's t test to determine differences in sex and race. RESULTS: The mean hook height was 9.8 ± 1.4 mm (range, 2.5-15.9 mm), whereas the mean hook height ratio was 0.42 ± 0.04 (range, 0.15-0.56). There was a 3.1% (62/2,000) incidence of abnormally small hooks, which we classified as hypoplastic and aplastic. Of the hypoplastic hooks, 55% (24/44) were bilateral, whereas 44% (8/18) of the aplastic hooks were bilateral. The incidence of variation in size in the hook of the hamate was highest in white females (9.3%) and lowest in black males (1.4%). CONCLUSIONS: Abnormalities in hook of hamate anatomy are common in the general population, especially in white females. CLINICAL RELEVANCE: Knowledge of anatomic variation in the hook of the hamate may provide additional insight into surgeons' palpation of bony anatomy, interpretation of imaging studies, and use of the hook as a landmark during surgery.

Quantitative trait loci for femoral size and shape in a genetically heterogeneous mouse population.

UNLABELLED: The aim of this study was to examine the genetic effects on cortical bone geometry. Genotypes from 487 mice were compared with geometric traits obtained from microCT. We found 14 genetic markers that associate with geometric traits, showing the complexity of genetic control over bone geometry. INTRODUCTION: Previous studies have shown that genetic background affects bone characteristics, particularly bone mineral density, in both mouse and human populations. Much less is known, however, about the effects of polymorphic genes on bone size, shape, and mechanical integrity. In this study, we investigated the genetic determinants of geometric properties of cortical bone in mice. MATERIALS AND METHODS: This study used a genetically heterogeneous mouse population, which is denoted UM-HET3 stock and is derived as the progeny of (BALB/cJ X C57BL/6J) F1 females and (C3H/HeJ X DBA/2J) F1 males. The experimental group consisted of 487 female UM-HET3 mice. Genotypic data from 99 polymorphic genetic loci was obtained from the mice at 4 weeks of age. At 18 months of age, the mice were humanely killed, and the right femurs were scanned with microcomputed tomography to assess geometric properties of cortical bone. A permutation-based test was used to detect significant associations between genetic markers and geometric traits. This test generates experiment-wise p values, which account for the effect of testing multiple hypotheses. An experiment-wise p < or = 0.05 was considered statistically significant. RESULTS: Fourteen genetic markers were found to significantly associate with one or more geometric traits. Two markers (D3Mit62 and D4Mit155) were associated with traits describing bone size; 2 (D12Mit167 and D14Mit170) were linked with traits describing bone shape; and 10 (D1Nds2, D5Mit95, D6Mit216, D7Mit91, D8Mit51, D9Mit110, D11Mit83, D15Mit100, D15Mit171, and D17Mit46) were associated with both size and shape. CONCLUSIONS: Our results indicate that the genetic control of cortical bone geometry is complex and that femoral size and shape may be influenced by different, although overlapping, groups of polymorphic loci.

Functional outcome after open reduction internal fixation of intra-articular fractures of the distal humerus in the elderly.

OBJECTIVE: We conducted a study to evaluate the functional outcomes of elderly patients after open reduction internal fixation of intra-articular distal humerus fractures. DESIGN: Retrospective clinical and radiographic evaluation. SETTING: A Level I trauma and tertiary referral center. PATIENTS/PARTICIPANTS: We identified 23 eligible patients aged older than 65 years from the center's orthopaedic trauma registry between 1997 and 2005. Fourteen patients were available for follow-up. We had a mean follow-up of 51 months with a range of 20 to 99 months. INTERVENTION: All enrolled patients were acutely treated with open reduction internal fixation of their distal humerus. MAIN OUTCOME MEASUREMENTS: All enrolled patients were contacted and evaluated radiographically and with physical examination. Functional outcome was assessed with the Mayo Elbow Performance, Disabilities of Arm and Shoulder and Hand, and Musculoskeletal Functional Assessment functional questionnaires. RESULTS: All 14 fractures united. The mean Mayo Elbow Performance score was 83. The mean elbow flexion-extension arc was 20° to 120°. There was no significant loss of forearm pronation-supination (P > 0.05) or grip strength (32.6 versus 34.0 lbs, P > 0.05) compared with the contralateral arm. The mean Disabilities of Arm and Shoulder and Hand score was 37.6. Musculoskeletal Functional Assessment scores demonstrated disability with a mean total score of 33.4 (normative 9.3), hand score of 34.7 (normative 3.7), and self-care score of 31.8 (normative 1.7). One patient required reoperation for a disabling flexion contracture. CONCLUSIONS: Intra-articular distal humerus fractures are severely disabling injuries, particularly in the elderly population. Good results can be achieved with stable fixation and fracture union. Despite reasonable range of motion, patient-directed questionnaires revealed persistent pain and functional limitations.