Rudimentary, “functionless” first metapodials of Canis latrans: Variation and association in length with longer,functional metapodials

A tenet of evolutionary theory is that phenotypic variation of a trait is inversely related to the intensity of stabilizing selection pressure. Among homologous bones, such as metapodials, a rudimentary, “nonfunctional” bone is expected to be more variable in length than nonrudimentary bones. This study compares variation and association in length among metapodials using 277 adult skeletons of Canis latrans. Canis latrans has a short, “functionless” first metacarpal (mc1) and “rudimentary, vestigial” first metatarsal (mt1). Results show that among the 10 metapodials, mt1 has the highest variation in length; other metapodials do not differ significantly from one another in their variation. Correlation coefficients for length of mc1 and mt1 with their ipsilateral metapodials 2-5 are significantly lower than coefficients for all other ipsilateral pairs. The correlation coefficient between left and right mt1 is significantly the lowest among all bilateral pairs of metapodials. Results are interpreted as follows. Mt1's high variation and low association in length are the outcome of less intense stabilizing selection pressure compared with other metapodials. The nonsignificant difference for variation in length between mc1 and metapodials 2-5 may be that mc1 is functional for development of a pollical dewclaw that helps restrain small prey.     

Robusticity and osteoarthritis at the trapeziometacarpal joint in a Bronze Age population from Tell Abraq, United Arab Emirates

Osteoarthritis (OA) is a progressive disease of the joints and can cause pain, reduced range of motion and strength, and ultimately loss of function at affected joints. Osteoarthritis often occurs at sites where biomechanical stress is acutely severe or moderate but habitual over the course of a lifetime. Skeletal remains from an Umm an-Nar tomb at Tell Abraq, United Arab Emirates (ca. 2300 BC), were recovered and represented over 300 individuals of all ages. The remains were disarticulated, commingled, and mostly fragmented. An analysis of 650 well-preserved adult metacarpal and carpal bones, from the tomb's western chamber, revealed that over 53% of the trapeziometacarpal joint facets showed signs of OA varying from mild to severe. The first and second metacarpals and trapezium bones were sided and evaluated for OA at the trapeziometacarpal joint articulations. Osteoarthritis was detected on 53% of the first metacarpals, 40% of the second metacarpals, and 57% of the trapezium bones. All specimens appeared enlarged, and the first metacarpals were assessed for sexual identification and robusticity. Eighty-five percent of the bones were probable males, and more than 80% of them had a robusticity index of 60 or higher. A strong correlation was found between OA, sex, and robusticity. High levels of OA and robusticity at the thumb suggest that the people of Tell Abraq were habitually involved in biomechanically challenging work with their hands.     

Bilateral asymmetry in the limb bones of the chimpanzee (Pan troglodytes)

There is much debate in behavioral primatology on the existence of population-level handedness in chimpanzees. The presence or absence of functional laterality in great apes may shed light on the origins of human handedness and on the evolution of cerebral asymmetry. The plasticity of long bone diaphyses in response to mechanical loading allows the functional interpretation of differences in cross-sectional geometric. While left-right asymmetry in upper limb diaphyseal morphology is a known property in human populations, it remains relatively unexplored in apes. We studied bilateral asymmetry in 64 skeletons of wild-caught chimpanzee using the humerus, second metacarpal, and femur. The total subperiosteal area (TA) of the diaphyses was measured at 40% of maximum humeral length and at the midshaft of the metacarpals and femora using external silicone molds. Overall, the TA values of the left humeri were significantly greater than the right, indicating directional asymmetry. This effect was even greater when the magnitude of difference in TA between each pair of humeri was compared. The right second metacarpals showed a tendency toward greater area than did the left, but this did not reach statistical significance. The lack of asymmetry in the femur serves as a lower limb control, and suggests that the upper limb results are not a product of fluctuating asymmetry. These findings imply behavioral laterality in upper limb function in chimpanzees, and suggest a complementary relationship between precision and power.     

第二掌骨长度与身高

本文通过对青藏高原海拔3000—4000米地区藏族、汉族7—18岁青少年1468人第二掌骨长度与身高的调查,探讨了二者的内在联系及规律。结果表明:第二掌骨长度与身高的增长近乎平行趋势,该二者之间存在着较高程度的正相关。第二掌骨长度/身高指数比较恒定,以第二掌骨长度推算身高是简便可行的。     

Age-related cortical bone loss in women from a 3rd-4th century AD population from England

Age-dependent cortical bone loss in adult females from a skeletal assemblage from 3rd-4th century AD England was studied using metacarpal radiogrammetry. Results showed reduced peak cortical bone thickness compared with modern subjects, and the magnitude of cortical bone loss in older females compared with their younger counterparts was greater than that documented for a modern reference population. An elevated prevalence of fractures classically associated with osteoporosis was also observed in the over-50-year cohort. The severity of osteoporosis in this group is difficult to explain in terms of extraneous factors relating to 3rd-4th century lifestyles. Given the important genetic component in osteoporosis, the results may indicate some inherent susceptibility in this particular population to the disease, and ways in which this possibility might be further explored are suggested.     

基于有限元的第5 掌骨颈骨折钢板螺钉内固定的生物力学分析

目的：应用有限元方法建立三种不同的治疗第5 掌骨颈骨折的钢板螺钉内固定模型,比较三种模型的生物力学稳定性,为 第5 掌骨颈骨折的临床早期功能康复提供参考。方法：选取一名健康青年志愿者,将CT 扫描数据导入三维有限元软件建立第5 掌骨颈骨折模型,并选取三种钢板螺钉内固定方法进行骨折固定。对三种模型施加外力荷载并进行生物力学有限元分析,对比骨 折断端的最大位移和钢板螺钉的应力分布情况。结果：方法一、二、三的第5 掌骨骨折端的最大位移分别为0.189775 mm、 0.181428 mm、0.224299 mm,以方法二的骨折端位移最小;内固定材料的最大应力分别为1.20 KPa、1.00 KPa、1.39 KPa,以方法二 的钢板螺钉应力最小。结论：采用近端三颗螺钉远端两颗螺钉的直型钢板内固定方法治疗第五掌骨颈骨折的生物力学稳定性更 好,术后早期功能锻炼的安全性更高,是治疗第5 掌骨颈骨折的理想内固定方法。     

Accelerated Return to Play in Professional Basketball Players With Surgically-Treated Metacarpal Shaft Fractures

BackgroundTraditional rehabilitation protocols for surgically treated metacarpal shaft fracture allow for return to play at 6-8 weeks post-operative. This may be devastating for the elite athlete. We outline a protocol that may allow for professional basketball players to successfully return to sport within four weeks following surgery.MethodsProfessional basketball players who sustained non-thumb metacarpal shaft fractures were included. All athletes underwent open reduction and internal fixation of the injured metacarpal. Patients were subsequently enrolled into an accelerated rehabilitation protocol.ResultsThe five athletes in our case series successfully passed return to sport testing within four weeks of surgery.ConclusionA plate and screw construct can potentially allow for professional basketball players to return to play in half the time. Future research studies should include a larger pool of athletes to further investigate accelerated rehabilitation following surgical fixation of metacarpal fractures. Level of Evidence: IV     

点压按摩第二掌骨全息穴点联合冲击波治疗慢性肩袖损伤的临床研究

摘要 目的：探究点压按摩第二掌骨全息穴点联合冲击波治疗慢性肩袖损伤患者的临床疗效。方法：选取2019年1月-2019年12月本院接诊的122例慢性肩袖损伤患者展开研究,使用随机数字表法将两组患者随机分为研究组和常规组,每组患者均61例。给予常规组患者体外冲击波治疗,在常规组治疗的基础上给予研究组患者第二掌骨全息穴点点压按摩治疗。观察两组患者的临床疗效、美国加州大学肩关节评分量表(UCLA)评分、视觉疼痛模拟评分（VAS）、肩关节活动度(ROM)以及并发症的发生率。结果：研究组患者的总有效率显著高于常规组（P＜0.05）;治疗后,两组患者的UCLA评分均得到显著改善,且研究组患者改善优于常规组（P＜0.05）;两组患者的VAS评分显著降低,且研究组患者VAS评分显著低于常规组（P＜0.05）;两组患者的前屈、外展、体侧外旋ROM均优于治疗前,研究组患者ROM显著优于常规组（P＜0.05）。治疗后随访1年,研究组患者并发症发生率显著低于常规组（P＜0.05）。结论：第二掌骨全息穴点点压按摩结合冲击波治疗慢性肩袖损伤患者,可以提升患者的临床疗效,改善患者的肩关节功能,减轻疼痛,降低患者的并发症,具有较高的临床意义,值得在临床推广使用。