Lansdown Drew A, Pedoia Valentina, Zaid Musa, Amano Keiko, Souza Richard B, Li Xiaojuan, Ma C Benjamin
Department of Orthopaedic Surgery, University of California, San Francisco, 1500 Owens Street, San Francisco, CA, 94158, USA.
Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, USA.
Clin Orthop Relat Res. 2017 Oct;475(10):2427-2435. doi: 10.1007/s11999-017-5368-8.
The factors that contribute to the abnormal knee kinematics after anterior cruciate ligament (ACL) injury and ACL reconstruction remain unclear. Bone shape has been implicated in the development of hip and knee osteoarthritis, although there is little knowledge about the effects of bone shape on knee kinematics after ACL injury and after ACL reconstruction. QUESTIONS/QUESTIONS: (1) What is the relationship between bony morphology with alterations in knee kinematics after ACL injury? (2) Are baseline bone shape features related to abnormal knee kinematics at 12 months after ACL reconstruction?
Thirty-eight patients (29 ± 8 years, 21 men) were prospectively followed after acute ACL injury and before ligamentous reconstruction. Patients were excluded if there was a history of prior knee ligamentous injury, a history of inflammatory arthritis, associated meniscal tears that would require repair, or any prior knee surgery on either the injured or contralateral side. In total, 54 patients were recruited with 42 (78%) patients completing 1-year followup and four patients excluded as a result of incomplete or unusable imaging data. MR images were obtained for the bilateral knees at two time points 1 year apart for both the injured (after injury but before reconstruction and 1 year after reconstruction) and contralateral uninjured knees. Kinematic MRI was performed with the knee loaded with 25% of total body weight, and static images were obtained in full extension and in 30° of flexion. The side-to-side difference (SSD) between tibial position in the extended and flexed positions was determined for each patient. Twenty shape features, referred to as modes, for the tibia and femur each were extracted independently from presurgery scans with the principal component analysis-based statistical shape modeling algorithm. Spearman rank correlations were used to evaluate the relationship between the SSD in tibial position and bone shape features with significance defined as p < 0.05. Each of the shape features (referred to as the bone and mode number such as Femur 18 for the 18th unique femoral bone shape) associated with differences in tibial position was then investigated by modeling the mean shape ± 3 SDs.
Two of the 20 specific femur bone shape features (Femur 10, Femur 18) and two of the 20 specific tibial bone shape features (Tibia 19, Tibia 20) were associated with an increasingly anterior SSD in the tibial position for the patients with ACL injury before surgical treatment. The shape features described by these modes include the superoinferior height of the medial femoral condyle (Femur 18; ρ = 0.33, p = 0.040); the length of the anterior aspect of the lateral tibial plateau (Tibia 20; ρ = -0.35, p = 0.034); the sphericity of the medial femoral condyle (Femur 10; ρ = -0.52, p < 0.001); and tibial slope (Tibia 19; ρ = 0.34; p = 0.036). One year after surgical treatment, there were two of 20 femoral shape features that were associated with SSD in the tibial position in extension (Femur 10, Femur 18), one of 20 femoral shape features associated with SSD in the tibial position in flexion (Femur 10), and three of 20 tibial shape features associated with SSD in the tibial position in flexion (Tibia 2, Tibia 4, Tibia 19). The shape features described by these modes include the sphericity of the medial femoral condyle (Femur 10; ρ = -0.38, p = 0.020); the superoinferior height of the medial femoral condyle (Femur 18; ρ = 0.34, p = 0.035); the height of the medial tibial plateau (Tibia 2; ρ = -0.32, p = 0.048); the AP length of the lateral tibial plateau (Tibia 4; ρ = -0.37, p = 0.021); and tibial slope (Tibia 19; ρ = 0.34, p = 0.038).
We have observed multiple bone shape features in the tibia and the femur that may be associated with abnormal knee kinematics after ACL injury and ACL reconstruction. Future directions of research will include the influence of bony morphology on clinical symptoms of instability in patients with and without ACL reconstruction and the long-term evaluation of these shape factors to better determine specific contributions to posttraumatic arthritis and graft failure.
Level II, therapeutic study.
前交叉韧带（ACL）损伤及ACL重建术后导致膝关节运动学异常的因素仍不明确。尽管关于骨形态对ACL损伤及ACL重建术后膝关节运动学的影响知之甚少，但骨形态已被认为与髋膝关节骨关节炎的发展有关。
（1）ACL损伤后骨形态与膝关节运动学改变之间有何关系？（2）ACL重建术后12个月时，基线骨形态特征与膝关节运动学异常是否相关？
38例患者（29±8岁，21例男性）在急性ACL损伤后、韧带重建术前进行前瞻性随访。如果患者有膝关节韧带损伤史、炎性关节炎病史、需要修复的相关半月板撕裂或受伤侧或对侧膝关节既往有手术史，则将其排除。总共招募了54例患者，其中42例（78%）完成了1年的随访，4例因影像学数据不完整或无法使用而被排除。在两个时间点分别对双侧膝关节进行磁共振成像（MR）检查，时间间隔为1年，检查对象包括受伤膝关节（受伤后但重建术前以及重建术后1年）和对侧未受伤膝关节。膝关节在承受25%体重负荷的情况下进行运动学MRI检查，并在完全伸直和屈曲30°时获取静态图像。确定每位患者在伸直和屈曲位置时胫骨位置的左右差异（SSD）。使用基于主成分分析的统计形状建模算法，从术前扫描中分别独立提取20个胫骨和股骨形状特征，称为模式。采用Spearman秩相关分析评估胫骨位置SSD与骨形态特征之间的关系，显著性定义为p<0.05。然后通过对平均形状±3个标准差进行建模，研究与胫骨位置差异相关的每个形状特征（称为骨和模式编号，如第18个独特股骨骨形状的股骨18）。
在手术治疗前，20个特定股骨骨形态特征中的2个（股骨10、股骨18）以及20个特定胫骨骨形态特征中的2个（胫骨19、胫骨20）与ACL损伤患者胫骨位置越来越靠前的SSD相关。这些模式所描述的形状特征包括股骨内侧髁的上下高度（股骨18；ρ=0.33，p=0.040）；胫骨外侧平台前缘的长度（胫骨20；ρ=-0.35，p=0.034）；股骨内侧髁的球形度（股骨10；ρ=-0.52，p<0.001）；以及胫骨斜率（胫骨19；ρ=0.34；p=0.036）。手术治疗1年后，20个股骨形状特征中有2个与伸直位胫骨位置的SSD相关（股骨10、股骨18），20个股骨形状特征中有1个与屈曲位胫骨位置的SSD相关（股骨10），20个胫骨形状特征中有3个与屈曲位胫骨位置的SSD相关（胫骨2、胫骨4、胫骨19）。这些模式所描述的形状特征包括股骨内侧髁的球形度（股骨10；ρ=-0.38），p=0.020）；股骨内侧髁的上下高度（股骨18；ρ=0.34，p=0.035）；胫骨内侧平台的高度（胫骨2；ρ=-0.32，p=0.048）；胫骨外侧平台的前后长度（胫骨4；ρ=-0.37，p=0.021）；以及胫骨斜率（胫骨19；ρ=0.34，p=0.038）。
我们观察到胫骨和股骨的多个骨形态特征可能与ACL损伤及ACL重建术后膝关节运动学异常有关。未来的研究方向将包括骨形态对有或无ACL重建患者不稳定临床症状的影响，以及对这些形状因素的长期评估，以更好地确定其对创伤后关节炎和移植物失败的具体作用。
二级，治疗性研究。
