Morphometrical variations of the carpal bones in thoroughbreds and ponies.

There is scant morphological data for equine carpal bones despite the frequent pathology in Thoroughbreds (TB). This study aimed to identify morphological and morphometrical variations and similarities in carpal bones between and within TB and Ponies (Po). Carpal bones from nine TB and 13 Po were prepared by boiling and drying. Lateromedial width, dorsopalmar depth, proximodistal height, relative density and volume of each bone were measured. Normalized measurements of the radial (Cr) and third (C3) carpal bones were significantly different in all dimensions, and there were significant variations in relative sizes of articular facets of the ulnar (Cu), C3 and fourth (C4) carpal bones between the groups. Bilaterally, the proportionate volume of the intermediate carpal bone (Ci) was significantly greater in Po while that of Cu and C4 were significantly greater in TB. Relative density of most bones was greater in Po. The palmar tuberosity of the proximal surface of Ci and palmar tubercle on the palmar surface of Cu were more prominent and relatively larger in TB. In the second carpal bone (C2), the distal extent of the proximal articular surface on the palmar surface was greater in Po. The inconsistent first carpal bone (C1) was relatively larger in Po. Morphometrical similarities and differences in carpal bones between TB and Po indicate potential effects of selection for body size or fast exercise.

The coracoclavicular ligaments: an anatomic study.

PURPOSE: The treatment for the acromioclavicular joint dislocations has focused on anatomic restoration of the coracoclavicular ligaments. We reviewed the detailed anatomy of trapezoid ligaments and conoid ligaments using cadavers. METHODS: The subjects were 40 shoulders of the 20 cadavers. We investigated the distributed direction and attachment sites of both trapezoid and conoid ligaments. RESULTS: The trapezoid ligaments began at about 2 cm away the central point of the distal coracoid process and directed toward the undersurface of the clavicle. The attachments extended from 13 to 26 mm in sagittal dimension and from 13 to 15 mm in coronal dimension. The conoid ligaments began at the medial posterior margin of the coracoid process and directed toward to the conoid tubercle in the clavicle. The attachments extended from 15 to 30 mm in sagittal dimension and from 3 to 6 mm in coronal dimension. CONCLUSION: The findings are important indices for the accurate reconstruction of the coracoclavicular ligaments in acromioclavicular joint dislocations.

Treatment of scaphotrapezio-trapezoid arthritis.

Arthritis of the scaphotrapeziotrapezoid (STT) joint presents with deep thenar eminence and thumb basilar pain and is often coexistent with carpometacarpal arthritis of the thumb. Conservative treatment includes splinting and corticosteroid injections. Operative treatment consists primarily of fusion of the STT joint, although alternatives include trapeziectomy, fibrous arthroplasty, and prosthetic replacements. When STT arthritis is coexistent with carpometacarpal arthritis, excision of the trapezium and proximal 2 mm of trapezoid has been recommended. Complications of surgery include pericarpal arthrosis, superficial radial nerve injury, and nonunion.

Anthropometric characteristics of wrists joint surfaces depending on lunate types.

It is well known that the lunate presents with two main types: lunate type I has one facet of its distal surface only for capitates, whereas lunate type II has two facets of the same surface for capitate and for hamate. Our previous anthropometric studies showed that the lunate type II wrists are of greater size than the lunate type I wrists. The aim of the present study was to determine whether the lunate types and the presence or absence of hamato-lunate joint correlate with anthropometric characteristics of the joint surfaces of other wrists. Sixteen sets of macerated wrists with the lunate type I and 21 with the lunate type II were studied. Two-thousand-four-hundred-and-forty-eight anthropometric measurements were done (for 68 anthropometric indicators) and 864 anthropometric indices were calculated (for 24 anthropometric indices) separately for the wrist joint surfaces. The absolute value of the anthropometric indicators of the joint surfaces of the separated wrists were greater in the wrists with the lunate type II, except for the indicators "Greatest length of the dorsal joint surface of pisiform", "Width of the proximal joint surface, measured in the middle" and "Greatest width of the proximal joint surface" for the trapezoid and "Greatest height of the ulnar joint surface" for the capitate. The enlargement of the joint surfaces for the scaphoid was mainly in proximo-distal direction. The enlargement for the triquetrum and pisiform was mainly in radio-ulnar direction. The enlargement for trapezium, trapezoid and capitate was mainly in dorso-volar direction (except for the ulnar joint surface of capitate). The enlargement for hamate was mainly in radio-ulnar and dorso-volar directions (except for the joint surfaces for capitate and triquetrum). The calculated indices illustrate the quantitative proportions of the variations mentioned above. The anthropometric differences are a good reason to make a clear distinction between both types of wrist joint complexes-with or without a hamato-lunate joint.

A 3D quantitative comparison of trapezium and trapezoid relative articular and nonarticular surface areas in modern humans and great apes.

The structure and functions of the modern human hand are critical components of what distinguishes Homo sapiens from the great apes (Gorilla, Pan, and Pongo). In this study, attention is focused on the trapezium and trapezoid, the two most lateral bones of the distal carpal row, in the four extant hominid genera, representing the first time they have been quantified and analyzed together as a morphological-functional complex. Our objective is to quantify the relative articular and nonarticular surface areas of these two bones and to test whether modern humans exhibit significant shape differences from the great apes, as predicted by previous qualitative analyses and the functional demands of differing manipulative and locomotor strategies. Modern humans were predicted to show larger relative first metacarpal and scaphoid surfaces on the trapezium because of the regular recruitment of the thumb during manipulative behaviors; alternatively, great apes were predicted to show larger relative second metacarpal and scaphoid surfaces on the trapezoid because of the functional demands on the hands during locomotor behaviors. Modern humans were also expected to exhibit larger relative mutual joint surfaces between the trapezoid and adjacent carpals than do the great apes because of assumed transverse loads generated by the functional demands of the modern human power grip. Using 3D bone models acquired through laser digitizing, the relative articular and nonarticular areas on each bone are quantified and compared. Multivariate analyses of these data clearly distinguish modern humans from the great apes. In total, the observed differences between modern humans and the great apes support morphological predictions based on the fact that this region of the human wrist is no longer involved in weight-bearing during locomotor behavior and is instead recruited solely for manipulative behaviors. The results provide the beginnings of a 3D comparative standard against which further extant and fossil primate wrist bones can be compared within the contexts of manipulative and locomotor behaviors.