Clinic of Orthopaedic and Traumatology, Polish Mother's Memorial Hospital Research Institute, Rzgowska 281/289, 93-338, Lodz, Poland.
Department of Arthroscopy, Minimally Invasive Surgery and Sports Traumatology, Medical University of Lodz, Żeromskiego 113, 90-549, Lodz, Poland.
BMC Musculoskelet Disord. 2021 Aug 28;22(1):740. doi: 10.1186/s12891-021-04636-4.
Biomechanical studies indicate that during outward rotation of the tibia and the valgus knee joint position, the patella is shifted in the lateral direction. After first-time patellar dislocation, the dynamic position of the femur in relation to the tibia plays an important role in joint stability, because the medial stabilizer of the patella (mostly the MPFL) is damaged or inefficient. The most important factor in controlling the rotational movement of the tibia in relation to the thigh are the hamstring muscles. The aim of the study therefore is to determine whether patients with patellar instability have a significant weakness in the knee flexor muscles, which can predispose to recurrent dislocations. This is an important consideration when planning the rehabilitation of patients with first-time patellar dislocation.
The study enrolled 33 patients with confirmed recurrent patellar dislocation, including six patients with bilateral involvement. In the study group, the hamstring muscles (both sides) were evaluated at velocities of 60 and 180 deg/s for the following parameters: peak torque, torque at 30 degrees of knee flexion, angle of peak torque and peak torque hamstring to quadriceps ratio (H/Q ratio).
In the recurrent patellar dislocation group, a statistically significant weakness in knee flexors was observed for both angular velocities compared to age and gender normative data. No such relationship was observed in the control group of heathy subjects. In patients with one-sided dislocation, no differences were found in knee flexors peak torque, torque at 30 degrees of knee flexion, angle of peak torque or H/Q ratio between the healthy and affected limbs for either angular velocity.
In patients with recurrent patellar dislocation, knee flexors strength is decreased significantly in both the unaffected and affected limbs. This may indicate a constitutional weakening of these muscles which can predispose to recurrent dislocations.
The study was retrospectively registered on ClinicalTrials.gov ( NCT04838158 ), date of registration; 22/03/2021.
生物力学研究表明，在胫骨向外旋转和膝关节外翻的位置，髌骨会向外侧移位。在初次髌骨脱位后，股骨相对于胫骨的动态位置在关节稳定性中起着重要作用，因为髌骨的内侧稳定器（主要是 MPFL）受损或效率降低。控制胫骨相对于大腿的旋转运动的最重要因素是腘绳肌。因此，本研究的目的是确定髌骨不稳定患者的膝关节屈肌是否存在明显的无力，这可能导致复发性脱位。这是计划初次髌骨脱位患者康复治疗时的一个重要考虑因素。
本研究纳入了 33 名确诊为复发性髌骨脱位的患者，其中 6 名患者存在双侧受累。在研究组中，对双侧腘绳肌（均进行评估），评估速度分别为 60 和 180°/s，评估参数包括：峰值扭矩、30°屈膝时的扭矩、峰值扭矩角度和股四头肌与腘绳肌峰值扭矩比（H/Q 比）。
与年龄和性别正常数据相比，在复发性髌骨脱位组中，两种角速度下的膝关节屈肌都存在明显的无力，而在健康对照组中则没有观察到这种关系。在单侧脱位患者中，在两种角速度下，健康和患侧肢体的膝关节屈肌峰值扭矩、30°屈膝时的扭矩、峰值扭矩角度或 H/Q 比均无差异。
在复发性髌骨脱位患者中，未受累和受累肢体的膝关节屈肌力量都明显减弱。这可能表明这些肌肉存在先天性的弱点，这可能导致复发性脱位。
本研究在 ClinicalTrials.gov 上进行了回顾性注册（NCT04838158），注册日期为 2021 年 3 月 22 日。
