Tantithawornwat Suphawat, Narkbunnam Rapeepat
J Med Assoc Thai. 2016 Nov;99(11):1226-32.
Total hip arthroplasty (THA) is an effective treatment to reduce pain and improve function outcomes for osteoarthritis patients. To our knowledge, there were scant of information about effect of preoperative leg length discrepancy (LLD) on recovery of hip abductor muscle strength and functional outcomes.
To evaluate the recovery of hip abductor muscle strength after THA in osteoarthritis patients with LLD and to study the correlation among LLD, recovery of hip abductor muscle strength and functional outcomes.
Between January 2014 and December 2015, 30 osteoarthritis patients who underwent THA at least six months were divided into two groups, Group 1 (LLD less than 2 cm), and Group 2 (LLD greater than 2 cm). Four parameters were measured on anteroposterior both hip radiographs in the supine position before and after operation: LLD, abductor length, abductor lever arm, and femoral offset (FO). Abductor muscle strength was calculated quantitatively by an isokinetic/isometric dynamometer [Con-Trex MJ]. Hip abductor strengths were calculated as the ratio of operated hip to contralateral healthy hip which used as controls. Functional outcomes were evaluated by two-minute walk test (2MWT) and timed up and go test (TUG).
The mean of hip abductor muscle strength ratio in all patients was 89.50% (standard deviation (SD) 29.94). Patients showed 83.10% (SD 34.58) of mean abductor muscle strength ratio at 6 to 12 months after operation, 88.50% (SD 25.36) at 12 to 24 months after operation, and 112.20% (SD 25.27) after 24 months after operation. Patients in Group 1 had 94.74% (SD 33.54) of mean hip abductor muscle strength ratio. It was greater than 79.02% (SD 18.18) in Group 2, however, there were no statistically significant differences between the two groups (p = 0.18). There were no significant differences of 2MWT and TUG between the two groups either. A weak correlation between preoperative LLD and hip abductor muscle strength ratio (rs = 0.163, p = 0.39), and between preoperative LLD and 2MWT (rs = 0.030, p = 0.874), TUG (rs = -0.067, p = 0.73) were found.
The hip abductor muscle strength showed good to excellent recovery after THA. The results from this study showed no correlation among preoperative LLD, the recovery of hip abductor muscle strength, and functional outcomes.
全髋关节置换术（THA）是减轻骨关节炎患者疼痛并改善功能结局的有效治疗方法。据我们所知，关于术前腿长差异（LLD）对髋外展肌力量恢复及功能结局影响的信息很少。
评估LLD的骨关节炎患者行THA后髋外展肌力量的恢复情况，并研究LLD、髋外展肌力量恢复与功能结局之间的相关性。
2014年1月至2015年12月期间，30例接受THA至少6个月的骨关节炎患者被分为两组，第1组（LLD小于2cm）和第2组（LLD大于2cm）。在仰卧位前后位双髋X线片上于手术前后测量四个参数：LLD、外展肌长度、外展肌杠杆臂和股骨偏心距（FO）。使用等速/等长测力计[Con-Trex MJ]定量计算外展肌力量。将患侧髋外展肌力量计算为与对侧健康髋（用作对照）的比值。通过两分钟步行试验（2MWT）和计时起立行走试验（TUG）评估功能结局。
所有患者髋外展肌力量比值的平均值为89.50%（标准差（SD）29.94）。患者在术后6至12个月时外展肌力量比值的平均值为83.10%（SD 34.58），术后12至24个月时为88.50%（SD 25.36），术后24个月后为112.20%（SD 25.27）。第1组患者髋外展肌力量比值的平均值为94.74%（SD 33.54）。该值大于第2组的79.02%（SD 18.18），然而，两组之间无统计学显著差异（p = 0.18）。两组之间的2MWT和TUG也无显著差异。发现术前LLD与髋外展肌力量比值之间存在弱相关性（rs = 0.163，p = 0.39），术前LLD与2MWT之间（rs = 0.030，p = 0.874）、TUG之间（rs = -0.067，p = 0.73）也存在弱相关性。
THA后髋外展肌力量显示出良好至优秀的恢复。本研究结果表明术前LLD、髋外展肌力量恢复与功能结局之间无相关性。
