Meniscal Treatment as a Predictor of Worse Articular Cartilage Damage on MRI at 2 Years After ACL Reconstruction: The MOON Nested Cohort

Abstract

Background: Patients undergoing anterior cruciate ligament reconstruction (ACLR) are at an increased risk for posttraumatic osteoarthritis (PTOA). While we have previously shown that meniscal treatment with ACLR predicts more radiographic PTOA at 2 to 3 years postoperatively, there are a limited number of similar studies that have assessed cartilage directly with magnetic resonance imaging (MRI).

Hypothesis: Meniscal repair or partial meniscectomy at the time of ACLR independently predicts more articular cartilage damage on 2- to 3-year postoperative MRI compared with a healthy meniscus or a stable untreated tear.

Study design: Cohort study; Level of evidence, 2.

Methods: A consecutive series of patients undergoing ACLR from 1 site within the prospective, nested Multicenter Orthopaedic Outcomes Network (MOON) cohort underwent bilateral knee MRI at 2 to 3 years postoperatively. Patients were aged <36 years without previous knee injuries, were injured while playing sports, and had no history of concomitant ligament surgery or contralateral knee surgery. MRI scans were graded by a board-certified musculoskeletal radiologist using the modified MRI Osteoarthritis Knee Score (MOAKS). A proportional odds logistic regression model was built to predict a MOAKS-based cartilage damage score (CDS) relative to the contralateral control knee for each compartment as well as for the whole knee, pooled by meniscal treatment, while controlling for sex, age, body mass index, baseline Marx activity score, and baseline operative cartilage grade. For analysis, meniscal injuries surgically treated with partial meniscectomy or meniscal repair were grouped together.

Results: The cohort included 60 patients (32 female; median age, 18.7 years). Concomitant meniscal treatment at the time of index ACLR was performed in 17 medial menisci (13 meniscal repair and 4 partial meniscectomy) and 27 lateral menisci (3 meniscal repair and 24 partial meniscectomy). Articular cartilage damage was worse in the ipsilateral reconstructed knee (P < .001). A meniscal injury requiring surgical treatment with ACLR predicted a worse CDS for medial meniscal treatment (medial compartment CDS: P = .005; whole joint CDS: P < .001) and lateral meniscal treatment (lateral compartment CDS: P = .038; whole joint CDS: P = .863). Other predictors of a worse relative CDS included age for the medial compartment (P < .001), surgically observed articular cartilage damage for the patellofemoral compartment (P = .048), and body mass index (P = .007) and age (P = .020) for the whole joint.

Conclusion: A meniscal injury requiring surgical treatment with partial meniscectomy or meniscal repair at the time of ACLR predicted worse articular cartilage damage on MRI at 2 to 3 years after surgery. Further research is required to differentiate between the effects of partial meniscectomy and meniscal repair.

Keywords: MRI; anterior cruciate ligament reconstruction; meniscus; posttraumatic osteoarthritis.

Figure 1:. Composite cartilage damage scores (CDS).

The primary outcome is a total of the sub-regional CDS for specified compartment or for the whole knee. Positive scores indicate higher grade cartilage loss in the ipsilateral surgical knee compartments relative to the contralateral control knee. The secondary outcome was the highest sub-regional MRI score in the specified compartment or throughout the whole knee. CDS = Cartilage Damage Score.

Figure 2:. Average primary cartilage damage score (CDS) in the tibiofemoral joint (2a) and patellofemoral joint (2b) with 95% confidence intervals by various patient characteristics.

Primary CDS refers to the totaled compartmental sum of each relative subcompartment MRI score (affected knee subcompartment minus same contralateral control knee subcompartment). “Cartilage damage” and “Patellofemoral cartilage grade” headers refer to baseline cartilage damage assessed surgically. The last box of 2a demonstrates the effect of meniscus treatment. Treatment group A refers to untreated menisci in that compartment, and treatment group B refers to treated menisci in that compartment. BMI = Body Mass Index.

Figure 2:. Average primary cartilage damage score (CDS) in the tibiofemoral joint (2a) and patellofemoral joint (2b) with 95% confidence intervals by various patient characteristics.

Primary CDS refers to the totaled compartmental sum of each relative subcompartment MRI score (affected knee subcompartment minus same contralateral control knee subcompartment). “Cartilage damage” and “Patellofemoral cartilage grade” headers refer to baseline cartilage damage assessed surgically. The last box of 2a demonstrates the effect of meniscus treatment. Treatment group A refers to untreated menisci in that compartment, and treatment group B refers to treated menisci in that compartment. BMI = Body Mass Index.

Figure 3:. Frequency of each sub-region as greatest compartmental nonzero cartilage damage score.

CDS = cartilage damage score, PMF = posterior medial femoral condyle, CMF = central medial femoral condyle, PMTP = posterior medial tibial plateau, CMTP = central medial tibial plateau, AMTP = anterior medial tibial plateau, PLF = posterior lateral femoral condyle, CLF = central lateral femoral condyle, PLTP = posterior lateral tibial plateau, CLTP = central lateral tibial plateau, ALTP = anterior lateral tibial plateau, MTr = medial trochlea, LTr = lateral trochlea, MP = medial patella, LP = lateral patella.

Figure 4:

Sagittal proton density weighted MR image of the lateral compartment of a knee 2 years post ACLR demonstrating high grade and full thickness cartilage loss in the lateral femoral condyle (large black arrow) at the site of a partial lateral meniscectomy (white arrow) as well as full thickness fissuring at the site of pivot shift impaction injury (small black arrow). Both of these cartilage lesions were associated with a degree of T2 bright bone marrow changes (not shown).

Figure 5:

Coronal 3D gradient echo MR image of a knee 2 years post ACLR demonstrating high grade and full thickness cartilage loss in the posterior and central medial tibial plateau with associated subchondral marrow edema (large white arrow) and subchondral cysts (small white arrow). Linear degenerative signal in the medial meniscus did not meet MR criteria for tear on proton density sequences (not shown).

Figure 6:

Coronal proton density fat saturated MR image of a knee database 2 years post ACLR demonstrating full thickness cartilage loss in the central lateral femoral condyle with associated bone marrow T2 signal (white arrow). The lateral meniscus appeared intact and there was no discernable impaction injury. Patient had a horizontal medial meniscus tear in this knee that is not optimally included in this image.

Figure 7:

Axial proton density (PD) fat saturated MR image of a contralateral control knee demonstrating full thickness chondral fissuring with cartilage delamination (small white arrow) in the medial patella with associated subchondral marrow edema.