Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, CB# 8700, 209 Fetzer Hall South Road, Chapel Hill, NC, 27599, USA.
Human Movement Science Curriculum, University of North Carolina at Chapel Hill, Fetzer Hall 209 South Road, Chapel Hill, NC, 27599, USA.
Knee Surg Sports Traumatol Arthrosc. 2019 Aug;27(8):2632-2642. doi: 10.1007/s00167-018-5290-y. Epub 2018 Dec 17.
Quadriceps weakness following anterior cruciate ligament reconstruction (ACLR) is linked to decreased patient-reported function, altered lower extremity biomechanics and tibiofemoral joint space narrowing. It remains unknown if quadriceps weakness is associated with early deleterious changes to femoral cartilage composition that are suggestive of posttraumatic osteoarthritis development. The purpose of the cross-sectional study was to determine if quadriceps strength was associated with T1ρ relaxation times, a marker of proteoglycan density, of the articular cartilage in the medial and lateral femoral condyles 6 months following ACLR. It is hypothesized that individuals with weaker quadriceps would demonstrate lesser proteoglycan density.
Twenty-seven individuals (15 females, 12 males) with a patellar tendon autograft ACLR underwent isometric quadriceps strength assessments in 90°of knee flexion during a 6-month follow-up exam. Magnetic resonance images (MRI) were collected bilaterally and voxel by voxel T1ρ relaxation times were calculated using a five-image sequence and a monoexponential equation. Following image registration, the articular cartilage for the weight-bearing surfaces of the medial and lateral femoral condyles (MFC and LFC) were manually segmented and further sub-sectioned into posterior, central and anterior regions of interest (ROI) based on the corresponding meniscal anatomy viewed in the sagittal plane. Univariate linear regression models were used to determine the association between quadriceps strength and T1ρ relaxation times in the entire weight-bearing MFC and LFC, as well as the ROI in each respective limb.
Lesser quadriceps strength was significantly associated with greater T1ρ relaxation times in the entire weight-bearing MFC (R = 0.14, P = 0.05) and the anterior-MFC ROI (R = 0.22, P = 0.02) of the ACLR limb. A post hoc analysis found lesser strength and greater T1ρ relaxation times were significantly associated in a subsection of participants (n = 18) without a concomitant medial tibiofemoral compartment meniscal or chondral injury in the entire weight-bearing MFC, as well as anterior-MFC and central-MFC ROI of the ACLR and uninjured limb.
The association between weaker quadriceps and greater T1ρ relaxation times in the MFC suggests deficits in lower extremity muscle strength may be related to cartilage composition as early as 6 months following ACLR. Maximizing quadriceps strength in the first 6 months following ACLR may be critical for promoting cartilage health early following ACLR.
Prognostic level 1.
前交叉韧带重建（ACLR）后股四头肌无力与患者报告功能下降、下肢生物力学改变和胫股关节间隙变窄有关。目前尚不清楚股四头肌无力是否与早期对股骨软骨成分的有害改变有关，这些改变提示创伤后骨关节炎的发展。本横断面研究的目的是确定 ACLR 后 6 个月，股四头肌力量是否与内侧和外侧股骨髁关节软骨的 T1ρ弛豫时间（一种蛋白聚糖密度的标志物）相关。假设股四头肌较弱的个体表现出较低的蛋白聚糖密度。
27 名（15 名女性，12 名男性）接受髌腱自体移植物 ACLR 的患者在 6 个月的随访检查中，在 90°膝关节屈曲下进行等长股四头肌力量评估。双侧采集磁共振图像（MRI），并使用 5 个图像序列和单指数方程计算体素 T1ρ弛豫时间。在图像配准后，根据矢状面观察到的相应半月板解剖结构，手动将负重面的内侧和外侧股骨髁（MFC 和 LFC）的关节软骨分割，并进一步分为后、中、前感兴趣区（ROI）。使用单变量线性回归模型确定 ACLR 肢体整个负重 MFC 和 LFC 以及每个肢体相应 ROI 中股四头肌力量与 T1ρ弛豫时间之间的关联。
股四头肌力量较弱与 ACLR 肢体整个负重 MFC（R=0.14，P=0.05）和前-MFC ROI（R=0.22，P=0.02）的 T1ρ弛豫时间增加显著相关。事后分析发现，在无内侧胫股关节间室半月板或软骨损伤的亚组参与者（n=18）中，股四头肌力量较弱与整个负重 MFC 以及 ACLR 和未受伤肢体的前-MFC 和中-MFC ROI 的 T1ρ弛豫时间显著相关。
MFC 中股四头肌较弱与 T1ρ弛豫时间增加之间的关联表明，下肢肌肉力量的缺陷可能早在 ACLR 后 6 个月就与软骨成分有关。在 ACLR 后最初的 6 个月内最大限度地增强股四头肌力量可能对促进 ACLR 后早期的软骨健康至关重要。
预测水平 1。
