Department of Orthopaedic Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo, 160-8582, Japan.
J Orthop Surg Res. 2021 Feb 2;16(1):102. doi: 10.1186/s13018-021-02252-5.
Although unloading of the joint is related to reduction of the local bone mineral density (BMD), little attention had been paid to the relationship between loading asymmetry and side-to-side difference of BMD in patients with bilateral knee osteoarthritis (OA). The aim of the present study was to evaluate and clarify the relationship between gait parameters and bone mineral density in those patients.
A total of 36 knees in eighteen patients (mean age = 73.7 ± 6.3 years, mean body mass index = 26.7 ± 3.8 kg/m) with bilateral medial knee OA were enrolled in the present study. All subjects performed relaxed standing and level walking at our gait laboratory after informed consent was obtained. First, ground reaction force was calculated on bilateral knees during standing. The knees in each patient were divided into higher and lower force side for the definition of dominant side limb. Second, gait parameters in each subject were obtained. To analyze the factors that affect the weight-bearing distribution in both limbs, clinical data and biomechanical parameters were compared between knees. Clinical data included radiographic OA grade, femorotibial angle, and BMD at the bilateral femoral neck.
Knees on higher force side were significantly more extended than on lower force side in standing (P = 0.012) and knee excursion during weight acceptance phase in gait was significantly larger in higher side than in lower side (P = 0.006), while the other parameters were not significantly different. As to the clinical data, higher force side had greater BMD, compared to lower force side. In terms of Kellgren-Lawrence scale and femorotibial angle on plain radiographs, there were no significant differences between higher and lower force side.
Based on loading asymmetry in the present study, lower BMD was observed on Lower force side in patients with knee OA. Therefore, it is helpful for orthopedic surgeons to examine side-to-side differences of bone mineral density or extension limitation during standing for evaluation of the loading condition in patients with bilateral knee OA.
虽然关节卸载与局部骨密度（BMD）降低有关，但对于双侧膝骨关节炎（OA）患者的负荷不对称与 BMD 两侧差异之间的关系，关注甚少。本研究旨在评估和阐明这些患者的步态参数与骨密度之间的关系。
本研究共纳入 18 例（平均年龄=73.7±6.3 岁，平均体重指数=26.7±3.8kg/m2）双侧膝关节内侧 OA 患者的 36 个膝关节。所有患者均在获得知情同意后在我们的步态实验室进行放松站立和水平行走。首先，在站立时计算双侧膝关节的地面反作用力。为了定义优势肢体，根据力的大小将每个患者的膝关节分为高力侧和低力侧。其次，获取每个受试者的步态参数。为了分析影响双下肢承重分布的因素，对膝关节的临床数据和生物力学参数进行了比较。临床数据包括放射 OA 分级、股胫角和双侧股骨颈的 BMD。
站立时，高力侧膝关节明显比低力侧膝关节伸展更多（P=0.012），而在步态的负重期，高力侧膝关节的膝关节活动度明显大于低力侧（P=0.006），而其他参数则无显著差异。就临床数据而言，高力侧的 BMD 高于低力侧。在 plain 射线片上的 Kellgren-Lawrence 分级和股胫角方面，高力侧和低力侧之间没有显著差异。
根据本研究中的负荷不对称，OA 患者的低力侧 BMD 较低。因此，对于骨科医生来说，在评估双侧膝关节 OA 患者的负荷情况时，检查站立时的骨密度或伸展受限的两侧差异有助于进行检查。
