桡骨畸形愈合后第一背侧伸肌间隔内的肌肉力臂：一项尸体研究。

LaRoque Elly S, Murray Wendy M, Langley Sarah, Hariri Sanaz, Levine Benjamin Parker, Ladd Amy L

Stanford University School of Medicine, Stanford, California, USA.

J Bone Joint Surg Am. 2008 Sep;90(9):1979-87. doi: 10.2106/JBJS.G.01015.

BACKGROUND

Functional loss is a common complication of the fractured distal part of the radius. The purpose of the present study was to determine if the moment arms of the first dorsal extensor compartment are altered by distal radial fracture malunion. We hypothesized that the moment arms of the abductor pollicis longus and extensor pollicis brevis are significantly affected by dorsal angulation, radial inclination, and radial shortening, the most common deformities accompanying distal radial malunion.

METHODS

Moment arms of the extensor pollicis brevis and abductor pollicis longus were estimated in twelve cadaver wrists with use of the tendon-displacement method, which involves calculating the moment arm as the derivative of tendon displacement with respect to joint angle. Tendon displacement was quantified in different wrist postures before and after a closing-wedge osteotomy simulating a complex malunion of an extra-articular radial fracture.

RESULTS

The simulated distal radial malunion resulted in a decrease in the wrist flexion moment arm for both the extensor pollicis brevis (p = 0.0003) and the abductor pollicis longus (p < 0.0001). The wrist flexion moment arms for the extensor pollicis brevis and abductor pollicis longus decreased by a mean (and standard deviation) of 114% +/- 75% and 77% +/- 50%, respectively, after the osteotomy. The wrist radial deviation moment arms for the extensor pollicis brevis and abductor pollicis longus increased by 16% +/- 26% (p = 0.071) and 28% +/- 44% (p = 0.043), respectively, after the osteotomy. Radiographs of the wrist that were made before and after the osteotomy indicated that radial tilt changed from 11.1 degrees of volar angulation to 14.8 degrees of dorsal angulation, radial inclination decreased from 21.8 degrees to 7.7 degrees, and radial height decreased from 11.6 to 4.4 mm.

CONCLUSIONS

Distal radial malunion alters the mechanical advantage of the muscles in the first dorsal extensor compartment.

背景

功能丧失是桡骨远端骨折常见的并发症。本研究的目的是确定桡骨远端骨折畸形愈合是否会改变第一背侧伸肌间隔的力臂。我们假设拇长展肌和拇短伸肌的力臂会受到背侧成角、桡侧倾斜和桡骨短缩（桡骨远端畸形愈合最常见的畸形）的显著影响。

方法

采用肌腱移位法在12具尸体手腕中估计拇短伸肌和拇长展肌的力臂，该方法涉及将力臂计算为肌腱位移相对于关节角度的导数。在模拟关节外桡骨骨折复杂畸形愈合的闭合楔形截骨术前和术后，在不同的手腕姿势下对肌腱位移进行量化。

结果

模拟的桡骨远端畸形愈合导致拇短伸肌（p = 0.0003）和拇长展肌（p < 0.0001）的腕关节屈曲力臂减小。截骨术后，拇短伸肌和拇长展肌的腕关节屈曲力臂平均（及标准差）分别下降了114%±75%和77%±50%。截骨术后，拇短伸肌和拇长展肌的腕关节桡偏力臂分别增加了16%±26%（p = 0.071）和28%±44%（p = 0.043）。截骨术前和术后的腕关节X线片显示，桡侧倾斜从掌侧成角11.1°变为背侧成角14.8°，桡侧倾斜度从21.8°降至7.7°，桡骨高度从11.6 mm降至4.4 mm。