Department of Rehabilitation, Faculty of Rehabilitation, Hiroshima International University, Hiroshima, Japan.
Graduate School of Medical Technology and Health welfare Sciences, Hiroshima International University, Hiroshima, Japan.
J Orthop Res. 2024 Jul;42(7):1490-1500. doi: 10.1002/jor.25812. Epub 2024 Feb 18.
Knee malalignment is a risk factor for patellar instability and patellofemoral osteoarthritis (PFOA), but etiologies remain unknown. We investigated the potential effects of decreased weight loading during growth on knee alignments and patellofemoral (PF) joint pathology. Hindlimb suspension (HS) was performed in 4-week-old female rats for 2, 4, and 8 weeks (HS groups). Age-matched rats were used as controls. Three-dimensional reconstructed images of the knee were obtained using X-ray computed tomography. Tibial tubercle-trochlear groove (TT-TG) distance, patellar tilt angle, and bisect offset were measured as indices of knee alignment. Histological analysis was also performed to evaluate the changes in cartilage and synovium in the PF joints. At Week 8, TT-TG distance, patella tilt angle, and bisect offset were significantly larger in the HS group than in the control group, respectively, indicating tibial external rotation, outward patellar tilt, and external displacement of the patella. Lateral patellar dislocation was frequently found in the HS group at Week 8 (five of eight knee joints, p < 0.05). Degenerative changes in the cartilage of the trochlear groove were observed at Week 8, and synovial changes such as hypertrophy and synovitis were observed at Weeks 4 and 8. Correlation analyses revealed significant relationships between the Mankin score and bisect offset, and between the OARSI synovitis score and all knee alignments indices. These results suggest that decreased weight loading on the lower extremities in growing rats resulted in knee malalignments characterized by external rotation of tibia and high incidence of lateral patellar dislocation with concomitant PFOA.
膝关节对线不良是髌骨不稳和髌股关节骨关节炎（PFOA）的危险因素，但病因仍不清楚。我们研究了生长过程中体重负荷降低对膝关节对线和髌股（PF）关节病理的潜在影响。4 周龄雌性大鼠进行后肢悬吊（HS）2、4 和 8 周（HS 组）。年龄匹配的大鼠作为对照组。使用 X 射线计算机断层扫描获得膝关节的三维重建图像。测量胫骨结节-滑车沟（TT-TG）距离、髌骨倾斜角和等分偏移作为膝关节对线的指标。还进行了组织学分析，以评估 PF 关节软骨和滑膜的变化。第 8 周时，HS 组 TT-TG 距离、髌骨倾斜角和等分偏移均明显大于对照组，分别提示胫骨外旋、髌骨外倾和髌骨外移。第 8 周 HS 组经常出现外侧髌骨脱位（8 个膝关节中有 5 个，p<0.05）。第 8 周时观察到滑车沟软骨的退行性改变，第 4 和 8 周时观察到滑膜增生和滑膜炎等变化。相关分析显示 Mankin 评分与等分偏移、OARSI 滑膜炎评分与所有膝关节对线指标之间存在显著相关性。这些结果表明，生长过程中下肢体重负荷降低导致膝关节对线不良，表现为胫骨外旋和外侧髌骨脱位发生率高，同时伴有 PFOA。
