Ultrasonographic Assessment of Femoral Cartilage in Individuals With Anterior Cruciate Ligament Reconstruction: A Case-Control Study

Abstract

Context Developing osteoarthritis is common after anterior cruciate ligament reconstruction (ACLR). Monitoring changes in femoral cartilage size after ACLR may be a way to detect the earliest structural alterations before the radiographic onset of osteoarthritis. Diagnostic ultrasonography (US) offers a clinically accessible and valid method for evaluating anterior femoral cartilage size. Objective To compare the US measurements of anterior femoral cross-sectional area and cartilage thickness between limbs in individuals with a unilateral ACLR and between the ACLR limbs of these individuals and the limbs of uninjured control participants. Design Case-control study. Setting Research laboratory. Patients or Other Participants A total of 20 volunteers with an ACLR (37.0 ± 26.6 months after surgery) and 28 uninjured volunteers. Main Outcome Measure(s) We used US to assess anterior femoral cartilage cross-sectional area and thickness (ie, medial, lateral, and intercondylar) in the ACLR and contralateral limbs of participants with ACLR and unilaterally in the reference limbs of uninjured participants. Results The ACLR limb presented with greater anterior femoral cartilage cross-sectional area (96.68 ± 22.68 mm2) than both the contralateral (85.69 ± 17.57 mm2, t19 = 4.47; P < .001) and uninjured (84.62 ± 15.89 mm2, t46 = 2.17; P = .04) limbs. The ACLR limb presented with greater medial condyle thickness (2.61 ± 0.61 mm) than both the contralateral (2.36 ± 0.47 mm, t19 = 2.78; P = .01) and uninjured limbs (2.22 ± 0.40 mm, t46 = 2.69; P = .01) and greater lateral condyle thickness (2.46 ± 0.65 mm) than the uninjured limb (2.12 ± 0.41 mm, t46 = 2.20; P = .03). Conclusions Anterior femoral cartilage cross-sectional area and thickness assessed via US were greater in the ACLR limb than in the contralateral and uninjured limbs. Greater thickness and cross-sectional area may have been due to cartilage swelling or hypertrophy after ACLR, which may affect the long-term health of the joint.

Managing the Early Risk of Posttraumatic Osteoarthritis Following Anterior Cruciate Ligament Injury

“…These data suggest that early cartilage thickening may predate the eventual cartilage thinning occurring later in the PTOA disease process. While the pathophysiology leading to a "thickening-to-thinning" cartilage response remain unknown, it has been hypothesized that change in cartilage composition may draw water into the cartilage resulting in a swelling of the cartilage tissue [20]. Further MRI research evaluating joint morphology has demonstrated changes in the shape or curvature of the femur and tibia within the first 5 years following ACL injury [25], providing evidence that significant changes to anatomical features occurs within the first 5 years following injury, which may be associated with the eventual development of PTOA.…”

“…Diagnostic ultrasound has been used to reliability visualize changes in femoral cartilage thickness and crosssectional area [19]. Greater femoral cross-sectional area, detected with diagnostic ultrasound, has been reported in patients with an ACLR [20], thus agreeing with data from other MRI studies [15]. Additionally, diagnostic ultrasound measures of femoral cartilage cross-sectional area is capable of evaluating the immediate response of the femoral cartilage to loading following walking, running, or jumping [18,19], suggesting that diagnostic ultrasound may provide a means for determining how cartilage responds to joint loading.…”

“…Additionally, diagnostic ultrasound measures of femoral cartilage cross-sectional area is capable of evaluating the immediate response of the femoral cartilage to loading following walking, running, or jumping [18,19], suggesting that diagnostic ultrasound may provide a means for determining how cartilage responds to joint loading. While diagnostic ultrasound may provide more accessible and cost-effective assessments of femoral cartilage, it is limited to evaluating articular cartilage in only certain regions of the femur [18][19][20] and future research is needed to determine if therapeutic ultrasound measures relate to PTOA development.…”

Reliability of a Novel Semiautomated Ultrasound Segmentation Technique for Assessing Average Regional Femoral Articular Cartilage Thickness

“…2 Although not yet validated, femoral articular cartilage echo intensity may also provide unique information about water content changes associated with early knee OA development. 3 Individuals with anterior cruciate ligament (ACL) injuries at elevated risk for OA demonstrate differences in ultrasound-based femoral articular cartilage thickness, 4 which provides preliminary evidence for the assessment's utility.…”

“…5 In addition, a single thickness location may not represent thickness throughout the entire cartilage region. 3,4 We have developed a novel semiautomated segmentation technique using a manual segmentation of the entire femoral cartilage CSA to automatically separate the cartilage into standardized regions normalized to cartilage length and calculate the average thickness within each region. This novel segmentation technique improves the ability of ultrasonography to assess femoral cartilage by providing an outcome that is representative of the thickness throughout standardized femoral regions while reducing the burden of manually measuring additional cartilage outcomes (ie, cartilage length or multiple compartments).…”