Do cartilage repair procedures prevent degenerative meniscus changes?: longitudinal t1ρ and morphological evaluation with 3.0-T MRI

Abstract

Background: Cartilage repair (CR) procedures are widely accepted for treatment of isolated cartilage defects in the knee joint. However, it is not well known whether these procedures prevent degenerative joint disease.

Hypothesis: Cartilage repair procedures prevent accelerated qualitative and quantitative progression of meniscus degeneration in individuals with focal cartilage defects.

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

Methods: Ninety-four subjects were studied. Cartilage repair procedures were performed on 34 patients (osteochondral transplantation, n = 16; microfracture, n = 18); 34 controls were matched. An additional 13 patients received CR and anterior cruciate ligament (ACL) reconstruction (CR&ACL), and 13 patients received only ACL reconstruction. Magnetic resonance imaging at 3.0-tesla with T(1ρ) mapping and sagittal fat-saturated intermediate-weighted fast spin echo (FSE) sequences was performed to quantitatively and qualitatively analyze menisci (Whole-Organ Magnetic Resonance Imaging Score [WORMS] assessment). Patients in the CR and CR&ACL groups were examined 4 months (n = 34; n = 13), 1 year (n = 21; n = 8), and 2 years (n = 9; n = 5) after CR. Control subjects were scanned at baseline and after 1 and 2 years, ACL patients after 1 and 2 years.

Results: At baseline, global meniscus T(1ρ) values (mean ± SEM) were higher in individuals with CR (14.2 ± 0.5 ms; P = .004) and in individuals with CR&ACL (17.1 ± 0.9 ms; P < .001) when compared with controls (12.8 ± 0.6 ms). After 2 years, there was a statistical difference between T(1ρ) at the overlying meniscus above cartilage defects (16.4 ± 1.0 ms) and T(1ρ) of the subgroup of control knees without cartilage defects (12.1 ± 0.8 ms; P < .001) and a statistical trend to the CR group (13.3 ± 1.0 ms; P = .09). At baseline, 35% of subjects with CR showed morphological meniscus tears at the overlying meniscus; 10% of CR subjects showed an increase in the WORMS meniscus score within the first year, and none progressed in the second year. Control subjects with (without) cartilage defects showed meniscus tears in 30% (5%) at baseline; 38% (19%) increased within the first year, and 15% (10%) within the second year.

Conclusion: This study demonstrated more severe meniscus degeneration after CR surgery compared with controls. However, progression of T(1ρ) values was not observed from 1 to 2 years after surgery. These results suggest that CR may prevent degenerative meniscus changes.

Figure 1

Global meniscus T_1ρ values 0.3, 1 and 2 years after cartilage repair (CR) compared to subjects 0.3, 1 and 2 years after combined CR and anterior cruciate ligament reconstruction (CR&ACL) and to controls at baseline and after 1 and 2 years. *P<0.05, compared to the control group at the according timepoint.

Figure 2

Global meniscus T_1ρ values of the control subgroup without cartilage defect at baseline and after 1 and 2 years, compared to meniscus T_1ρ at the overlying meniscus above the cartilage defect in the control subgroup with cartilage defect (Defect) and compared to meniscus T_1ρ at the overlying meniscus above the cartilage repair region in the cartilage repair group (CR) 0.3, 1 and 2 years after surgery. *P<0.05, compared to the control subgroup without cartilage defect (No) at the according timepoint. **=0.055.

Figure 3

T_1ρ values of the overlying meniscus above the repair region in subjects with osteochondral transplantation (OCT) and subjects with microfracture procedure (Mfx) 0.3, 1 and 2 years after surgery. Differences between the groups were not significant (P>0.05).

Figure 4

Prevalence of morphological meniscus lesions. Green color indicates no meniscus lesion, yellow simple and red complex meniscus lesions. A: Lesions at the overlying meniscus above cartilage repair regions in the cartilage repair group (CR) and above cartilage defects in the control subgroup with cartilage defect (Defect) were compared to the control subgroup without cartilage defect (No). B: Lesions at the medial (MM) and lateral meniscus (LM) in the group with reconstruction of the anterior cruciate ligament (ACL; 1 year after surgery) and the group with combined CR and ACL surgery (CR&ACL), respectively.

Figure 5

T_1ρ color maps of the anterior and posterior horn of the medial meniscus of 1 year and 2 year follow-up time-points, overlaid with the first-echo images. Superior: Control subject with cartilage defect at the medial femoral condyle, who did not receive a cartilage repair (CR) procedure. Inferior: CR subject with osteochondral transplantation at the medial femoral condyle. Blue color indicates low, red color high meniscus T_1ρ values. Subjects with untreated cartilage lesion showed a higher increase in T_1ρ values over time compared to the subject with CR.