Department of Research, Cleveland Clinic Akron General, Akron, OH, USA.
Department of Orthopedic Surgery, Akron Children's Hospital, Akron, OH, USA.
Knee Surg Sports Traumatol Arthrosc. 2018 Oct;26(10):2883-2890. doi: 10.1007/s00167-017-4799-9. Epub 2017 Nov 11.
Graft tensioning during medial patellofemoral ligament (MPFL) reconstruction typically allows for lateral patellar translation within the trochlear groove. Computational simulation was performed to relate the allowed patellar translation to patellofemoral kinematics and contact pressures.
Multibody dynamic simulation models were developed to represent nine knees with patellar instability. Dual limb squatting was simulated representing the pre-operative condition and simulated MPFL reconstruction. The graft was tensioned to allow 10, 5, and 0 mm of patellar lateral translation at 30° of knee flexion. The patellofemoral contact pressure distribution was quantified using discrete element analysis.
For the 5 and 10 mm conditions, patellar lateral shift decreased significantly at 0° and 20°. The 0 mm condition significantly decreased lateral shift for nearly all flexion angles. All graft conditions significantly decreased lateral tilt at 0°, with additional significant decreases for the 5 and 0 mm conditions. The 0 mm condition significantly increased the maximum medial pressure at multiple flexion angles, increasing by 57% at 30°, but did not alter the maximum lateral pressure.
Allowing 5 to 10 mm of patellar lateral translation limits lateral maltracking, thereby decreasing the risk of post-operative recurrent instability. Allowing no patellar translation during graft tensioning reduces maltracking further, but can overconstrain the patella, increasing the pressure applied to medial patellar cartilage already fibrillated or eroded from an instability episode.
在进行内侧髌股韧带（MPFL）重建时，通常会对移植物进行张力调整，以允许髌骨在滑车沟内发生外侧平移。本研究通过计算模拟的方法，旨在研究允许的髌骨平移与髌股关节运动学和接触压力之间的关系。
建立了代表 9 例髌股关节不稳定患者的多刚体动力学模拟模型。采用双下肢深蹲模拟术前状态和模拟 MPFL 重建。在 30°膝关节屈曲时，对移植物进行张力调整，以允许髌骨发生 10、5 和 0mm 的外侧平移。采用离散元分析方法对髌股接触压力分布进行量化。
在 5mm 和 10mm 两种情况下，髌骨在 0°和 20°时的外侧移位显著减小。0mm 条件下，几乎所有屈曲角度的髌骨外侧移位都显著减小。所有移植物条件下，髌骨在 0°时的外侧倾斜显著减小，5mm 和 0mm 条件下的髌骨外侧倾斜进一步显著减小。0mm 条件显著增加了多个屈曲角度的最大内侧压力，在 30°时增加了 57%，但没有改变最大外侧压力。
允许髌骨发生 5 至 10mm 的外侧平移可以限制髌骨外侧脱位，从而降低术后复发性不稳定的风险。在移植物张力调整过程中不允许髌骨发生任何平移可以进一步减少脱位，但可能会过度限制髌骨，增加已经因不稳定事件而出现纤维化或侵蚀的内侧髌股软骨的压力。
