Cartilage adaptation after anterior cruciate ligament injury and reconstruction: implications for clinical management and research? A systematic review of longitudinal MRI studies.

OBJECTIVE: To summarize the current evidence of magnetic resonance imaging (MRI)-measured cartilage adaptations following anterior cruciate ligament (ACL) reconstruction and of the potential factors that might influence these changes, including the effect of treatment on the course of cartilage change (i.e., surgical vs non-surgical treatment). METHODS: A literature search was conducted in seven electronic databases extracting 12 full-text articles. These articles reported on in vivo MRI-related cartilage longitudinal follow-up after ACL injury and reconstruction in "young" adults. Eligibility and methodological quality was rated by two independent reviewers. A best-evidence synthesis was performed for reported factors influencing cartilage changes. RESULTS: Methodological quality was heterogenous amongst articles (i.e., score range: 31.6-78.9%). Macroscopic changes were detectable as from 2 years follow-up next to or preceded by ultra-structural and functional (i.e., contact-deformation) changes, both in the lateral and medial compartment. Moderate-to-strong evidence was presented for meniscal lesion or meniscectomy, presence of bone marrow lesions (BMLs), time from injury, and persisting altered biomechanics, possibly affecting cartilage change after ACL reconstruction. First-year morphological change was more aggravated in ACL reconstruction compared to non-surgical treatment. CONCLUSION: In view of osteoarthritis (OA) prevention after ACL reconstruction, careful attention should be paid to the rehabilitation process and to the decision on when to allow return to sports. These decisions should also consider cartilage fragility and functional adaptations after surgery. In this respect, the first years following surgery are of paramount importance for prevention or treatment strategies that aim at impediment of further matrix deterioration. Considering the low number of studies and the methodological caveats, more research is needed.