尺骨鹰嘴骨折不同程度骨量丢失对肘关节稳定性的影响

Effects of bone defects on elbow stability in olecranon fractures

目的 探讨尺骨鹰嘴骨折时不同程度骨量丢失对肘关节稳定性的影响.方法 取10具20侧男性新鲜上技标本,在距尺骨鹰嘴尖部10 mm处向远端截骨,制备鹰嘴中部不同程度骨缺损,即骨量丢失模型,截骨分为4组,每组5侧上肢标本,即尺骨鹰嘴完整组、截除3mm组、截除6mm组、截除9 mm组,骨折断端予张力带内固定后,测量每组肘关节屈伸活动范围变化及肘关节在屈曲30°、60°、90°、120°时,前臂施加1.96 N·m扭距,肘关节内外翻角度的变化,同时观察肱尺关节关系.结果当尺骨鹰嘴截骨至3 mm时,肘关节的伸直活动开始受限;当尺骨鹰嘴截骨至6 mm时,CB片示肱尺关节出现不服贴,鹰嘴尖紧贴滑车关节面,滑车与鹰嘴之间间隙增大,肘关节的伸直活动明显受限;当尺骨鹰嘴截骨至9mm时,CR片示肘关节明显处于半脱位,滑车切迹的弧度基本消失.肘关节屈曲30°、60°、90°时,随截骨量增大肘外翻角度增大,当截骨量达到6 mm时外翻角度明显增大,差异有统计学意义（P＜0.05）.而肘关节屈曲30°、60°、90°、120°时,内翻角度组间差异无统计学意义（P＞0.05）.结论 尺骨鹰嘴中部截骨缩短达到6mm时,滑车切迹弧度发生改变,出现肘关节不稳定.临床对于尺骨鹰嘴中部粉碎性骨折如短缩不超过6 mm可单纯固定,否则应考虑原位植骨内固定.

Objective To investigate effects of different bone defects on stability of the elbow in the olecranon fracture. Methods Ten fresh cadavers with 20 upper extremities were used in the present study. Different models of bone defects in the middle olecranon were created by cutting the bone from 10 mm below the olecranon process. The 20 specimens were randomly made into intact, 3 mm defect, 6 mm defect and 9 mm defect groups. After osteotomy fixations were applied with the tension band wire. Changes in the range of motion of the elbow joint were measured. When the elbow was flexed at 30°, 60°, 90°, and 120°, a and the varus angulations in the varus test position, and observe the changes in relationship to the humeroulnar joint. Results Extension of the elbow was limited when the defect was 3 mm. X-ray showed that the extension of the elbow was obviously limited when the defect was 6 mm, with the humeroulnar joint moving resistantly, the olecranon process completely touching the surface of the trochlear and the interspace between the humeroulnar joint increasing. When the defect was up to 9 mm, the humeroulnar joint was subluxated obviously,with the trochlear notch nearly disappearing. Given the same degree of elbow flexion, the valgus angulation increased with the defect, especially when the defect was beyond6 mm （P 〈0.05）. Conclusions When the bone defect at the middle olecranon reaches 6 mm, the trochlear notch radian will change, leading to an unstable elbow joint. Consequently, comminuted fractures of the middle olecranon can be treated with fixation if the defect is less than 6 mm： Otherwise bone grafting may be necessary to recover the trochlear notch radian and reduce the risk of traumatic osteoarthritis.