School of Allied Health, La Trobe University, Victoria, Australia.
Faculty of Medicine, Nursing and Health Sciences, Monash University, Victoria, Australia.
Am J Sports Med. 2020 Jun;48(7):1711-1719. doi: 10.1177/0363546520914628. Epub 2020 May 6.
Patellofemoral joint (PFJ) osteoarthritis may occur after anterior cruciate ligament reconstruction (ACLR). The mechanisms underpinning the development of PFJ osteoarthritis are not known but may relate to altered PFJ loading. Few studies have assessed PFJ loads during high-impact tasks, such as running, beyond the acute rehabilitation phase (ie, >12 months) after ACLR.
PURPOSE/HYPOTHESIS: The purpose was to compare between-limb joint angles, joint moments, and PFJ contact force during running in individuals at 12 to 24 months after unilateral ACLR. We hypothesized that peak knee flexion angle, knee extension moment, and PFJ contact force during stance would be lower in the ACLR limb compared with the uninjured limb.
Controlled laboratory study.
A total of 55 participants (mean ± SD age, 28 ± 7 years), 12 to 24 months after ACLR, ran at a self-selected speed (2.9 ± 0.3 m/s). Measured kinematics and ground-reaction forces were input into musculoskeletal models to calculate joint moments and muscle forces. These values were subsequently input into a PFJ model to calculate contact force peak and impulse. Outcome measures were compared between the ACLR and uninjured limbs.
In the ACLR limb, compared with the uninjured limb, the PFJ contact force displayed a lower peak (ACLR, 6.1 ± 1.3 body weight [BW]; uninjured, 6.7 ± 1.4 BW; < .001) and impulse (ACLR, 0.72 ± 0.17 BWseconds [BWs]; uninjured, 0.81 ± 0.17 BWs; < .001). At the time of the peak PFJ contact force, the knee extension moment was lower in the ACLR limb (ACLR, 14.0 ± 2.4 %BWheight [%BWHT]; uninjured, 15.5 ± 2.5 %BWHT; < .001). The opposite was true for the ankle plantarflexion moment (ACLR, 12.1 ± 2.6 %BWHT; uninjured, 11.5 ± 2.7 %BWHT; = .019) and the hip extension moment (ACLR, 2.3 ± 2.5 %BWHT; uninjured, 1.6 ± 2.3 %BWHT; = .013). The foot-ground center of pressure was located more anteriorly with respect to the ankle joint center (ACLR, 5.8 ± 0.9 %height [%HT]; uninjured, 5.4 ± 1.0 %HT; = .001). No differences were found for the sagittal plane hip, knee, and ankle angles.
The ACLR limb experienced lower peak PFJ loads during running, explained by a small anterior shift in the foot-ground center of pressure during stance that offloaded the torque demand away from the ACLR knee.
Lower net PFJ loading during running in the ACLR limb more than 12 months after ACLR suggests that underloading might play a role in the onset of PFJ osteoarthritis after ACLR.
前交叉韧带重建（ACLR）后可能会发生髌股关节（PFJ）骨关节炎。导致 PFJ 骨关节炎发展的确切机制尚不清楚，但可能与 PFJ 负荷改变有关。很少有研究评估 ACLR 后 12 个月（即急性康复期后）进行高强度活动（如跑步）时的 PFJ 负荷。
目的/假设：本研究的目的是比较 ACLR 后 12 至 24 个月个体跑步时双侧膝关节角度、关节力矩和 PFJ 接触力。我们假设在 ACLR 侧，与未受伤侧相比，在支撑相时，膝关节最大屈曲角度、膝关节伸展力矩和 PFJ 接触力会更低。
对照实验室研究。
共有 55 名参与者（平均年龄±标准差，28±7 岁），在 ACLR 后 12 至 24 个月，以自我选择的速度（2.9±0.3m/s）跑步。测量运动学和地面反作用力被输入到肌肉骨骼模型中，以计算关节力矩和肌肉力。这些值随后被输入到 PFJ 模型中，以计算接触力峰值和冲量。比较 ACLR 和未受伤侧的结果测量值。
在 ACLR 侧，与未受伤侧相比，PFJ 接触力的峰值较低（ACLR，6.1±1.3 体重[BW]；未受伤，6.7±1.4 BW；<0.001）和冲量（ACLR，0.72±0.17 BW秒[BWs]；未受伤，0.81±0.17 BWs；<0.001）。在 PFJ 接触力峰值时，ACL 侧的膝关节伸展力矩较低（ACLR，14.0±2.4% BW身高[%BWHT]；未受伤，15.5±2.5% BWHT；<0.001）。相反，踝关节跖屈力矩（ACLR，12.1±2.6% BWHT；未受伤，11.5±2.7% BWHT；=0.019）和髋关节伸展力矩（ACLR，2.3±2.5% BWHT；未受伤，1.6±2.3% BWHT；=0.013）较高。与踝关节中心相比，足底压力中心更向前（ACLR，5.8±0.9% 高度[%HT]；未受伤，5.4±1.0% HT；=0.001）。在矢状面髋关节、膝关节和踝关节角度方面没有发现差异。
在 ACLR 侧，跑步时 PFJ 峰值负荷较低，这是由于在支撑相时足底压力中心向前小幅度移位，从而减轻了 ACLR 膝关节的扭矩需求。
ACL 后 12 个月以上跑步时 PFJ 净负荷较低，提示 ACLR 后 PFJ 骨关节炎的发生可能与负荷不足有关。
