Shriners Children's, Gerald F. Harris Motion Analysis Center, Chicago, IL.
Marquette University, Biomedical Engineering, Milwaukee, WI.
J Pediatr Orthop. 2024 Aug 1;44(7):e598-e603. doi: 10.1097/BPO.0000000000002704. Epub 2024 May 6.
Though the primary goal for limb length discrepancy (LLD) management is to equalize the leg lengths, symmetry between corresponding long bones is usually not achieved, leading to knee height asymmetry (KHA). To date, there is minimal information on what effect KHA has on gait biomechanics and joint loading. Thus, the purpose of this study is to determine the impact of KHA on gait biomechanics.
Seventeen subjects with KHA after limb equalizing surgery and 10 healthy controls were enrolled. Subjects participated in 3D gait analysis collected using self-selected speed. Lower extremity kinematics, kinetics, work generated/absorbed, and total work were calculated. Standing lower limb x-rays and scanograms were used to measure LLD and calculate the tibia-to-femur (TF) ratio for each limb. Two sample t tests were used to compare differences in standing LLD, TF ratio, and work between groups. Bivariate correlation using Pearson correlation coefficients was conducted between TF ratio and total mechanical work, as well as between knee height asymmetry indices and total work asymmetry (α=0.05).
Among participants, there were no differences between LLD; however, there were differences between TF ratio and knee height asymmetry. We found a nonsignificant relationship between TF ratio and total mechanical work for individual lower extremities. Therefore, the length of individual bones (TF ratio) relative to each other within the individual lower extremity was not associated with the amount of work produced. However, when a difference exists between sides (asymmetry, ie, TF ratio asymmetry), there were associated differences in work (work asymmetry) produced between sides (r=0.54, P =0.003). In other words, greater knee height asymmetry between limbs resulted in more asymmetrical mechanical work during walking.
These findings may have implications for the management of LLD. Asymmetrical total mechanical work could lead to atypical joint loading during gait. Surgeons may want to consider prioritizing achieving knee height symmetry as a postoperative goal when correcting limb length discrepancy.
Level III, Case Control Study.
尽管肢体长度差异（LLD）管理的主要目标是使腿长相等，但相应长骨之间通常无法达到对称，从而导致膝关节高度不对称（KHA）。迄今为止，关于 KHA 对步态生物力学和关节负荷的影响的信息很少。因此，本研究的目的是确定 KHA 对步态生物力学的影响。
招募了 17 名接受肢体均衡手术后存在 KHA 的患者和 10 名健康对照者。参与者以自身选择的速度参与 3D 步态分析。计算下肢运动学、动力学、产生/吸收的功和总功。使用站立下肢 X 射线和扫描图测量 LLD 并计算每条肢体的胫骨到股骨（TF）比。使用两样本 t 检验比较两组之间站立 LLD、TF 比和功的差异。使用 Pearson 相关系数进行双变量相关性分析，以确定 TF 比与总机械功之间以及膝关节高度不对称指标与总功不对称之间的相关性（α=0.05）。
在参与者中，LLD 之间没有差异；然而，TF 比和膝关节高度不对称之间存在差异。我们发现个体下肢的 TF 比与个体下肢的总机械功之间没有显著关系。因此，个体骨骼之间的长度（TF 比）相对于个体下肢彼此之间没有与产生的功量相关。然而，当两侧存在差异（即，TF 比不对称）时，两侧之间的功（功不对称）也存在差异（r=0.54，P=0.003）。换句话说，四肢之间更大的膝关节高度不对称会导致步行时机械功更不对称。
这些发现可能对 LLD 的管理具有意义。不对称的总机械功可能导致步态期间关节负荷异常。外科医生可能希望考虑将术后实现膝关节高度对称作为纠正肢体长度差异的目标。
三级，病例对照研究。
