内侧副韧带、桡骨头影响肘关节外翻稳定性的生物力学研究

Biomechanical research on the effect of the medial collateral ligament and radial head to valgus stability of the elbow

摘要:

目的 探讨内侧副韧带( medial collateral ligament，MCL )、桡骨头对肘关节外翻稳定性的影响，评价单独或联合修复MCL、固定桡骨头骨折的相对效果，明确桡骨头切除后MCL修复能否有效恢复肘关节稳定性。方法 选取6具成人新鲜冰冻上肢标本，制作肘关节骨-韧带标本，在0.75 N·m的外翻载荷下测量不同屈曲角度肱尺关节的外翻松弛度。首先测量完整肘关节标本，然后按以下步骤顺序测试：1)MCL切断；2)MCL修复；3)MCL切断+桡骨头骨折；4)MCL修复+桡骨头骨折；5)MCL切断+桡骨头固定；6)MCL修复+桡骨头固定；7) MCL修复+桡骨头切除。实验数据用SPSS 23.0 统计软件分析。结果 切断MCL使外翻松弛度增加，与完整关节相比差异有统计学意义(P=0.005)。修复MCL可降低外翻松弛度，与完整关节相比差异无统计学意义(P=0.690)。再次切断MCL后造成桡骨头骨折，使外翻松弛度明显增加，与仅切断MCL相比差异有统计学意义(P=0.004)。当处于MCL切断+桡骨头骨折损伤状态下，单独修复MCL使外翻松弛度明显降低，与完整关节相比差异无统计学意义(P=0.061)；单独固定骨折使外翻松弛度下降，与完整关节相比差异有统计学意义(P=0.005)；给予修复MCL联合骨折固定，外翻松弛度明显下降，与完整关节相比差异无统计学意义(P=0.054)。修复MCL后切除桡骨头，外翻松弛度与完整关节相比差异无统计学意义(P=0.050)。结论 1)，MCL损伤即可引起肘外翻不稳定，合并桡骨头骨折，则导致严重外翻不稳定。单独修复MCL优于单独固定桡骨头骨折，足以恢复外翻稳定性。2)，对于MCL损伤合并桡骨头粉碎性骨折无法重建的患者，修复MCL、切除桡骨头可能是一种安全、有效的手术方式。

Abstract:

Objective: To investigate the influence of the medial collateral ligament (MCL) and radial head to valgus stability of the elbow, evaluate the relative efficacy of fixation of the radial head and repair of the MCL isolated or in combination, and determine whether repair of the MCL could restore valgus stability in the absence of the radial head. Methods: Six fresh-frozen adults upper limb specimens were selected to make bone-ligament specimens of the elbow. MTS 858 Bionix test system was used to apply a valgus torque of 0.75 N·m to the elbow specimens. The digital speckle correlation method was used to measure the valgus laxity of the ulnohumeral articulation at different flexion angles of the elbow. The testing protocol was carried out on the intact elbows and after each step in the following sequence: 1) MCL division; 2) MCL repair; 3) MCL re-release and fracture of the radial head; 4) MCL repair; 5) MCL re-release and internal fixation of the radial head; 6) MCL repair with the fixation still in situ; and 7) MCL repair and excision of the radial head. The experimental data were analyzed by SPSS 23.0 statistical software. Results: Section of the MCL increased valgus laxity, which was statistically significant compared with the intact elbows (P = 0.005). Repair of the MCL corrected the laxity with a mean reduction of 0.04 ± 0.51° compared with the intact joints, which was not significant (P = 0.690). After re-section of the MCL, fracture of the radial head produced a mean increase of valgus laxity of 9.31 ± 2.45° compared with the MCL-deficient elbow (P = 0.004). In the case of radial head fracture and MCL division, isolated repair of the MCL reduced valgus laxity to a mean of 0.54 ± 0.66° compared with the intact joints, which was not significant (P = 0.061). Isolated fixation of the radial head reduced laxity to a mean of 4.10 ± 2.43° greater than that of the intact elbows, which was significant (P = 0.005). After combined repair of the MCL and fixation of the radial head, the mean valgus laxity is not significantly different from that of the intact elbows (P = 0.054). After repair of the MCL, excision of the radial head produced a mean increase of valgus laxity of 0.79 ± 1.15° compared with the intact elbows, which was not significant (P = 0.050). Conclusions: 1). Division of the MCL can lead to valgus instability of the elbow. Subsequent fracture of the radial head can lead to severe valgus instability. Isolated repair of the MCL is superior to isolated fixation of the radial head and may be sufficient to restore valgus stability after fractures of the radial head and division of the MCL. 2). For patients with disruption of the MCL and unreconstructable fractures of the radial head, repair of the MCL and resection of the radial head may be a safe and effective procedure.