Knee osteoarthritis in traumatic knee symptoms in general practice: 6-year cohort study.

AIM:
To identify degenerative knee abnormalities using MRI and radiography 6 years after knee trauma, their relation with persistent knee symptoms and baseline prognostic factors.

METHODS:
Adults (18-65 years) with incident traumatic knee symptoms visiting their general practitioner were followed up for 6 years and underwent baseline MRI and 6-year follow-up MRI and radiography. Logistic regression was used to analyse associations between various degenerative abnormalities on 6-year MRI and radiography, persistent knee symptoms and baseline prognostic factors for knee osteoarthritis (OA) on 6-year MRI.

RESULTS:
On 6-year radiography, 60% of patients showed no OA, 28% showed OA with Kellgren&Lawrence (K&L) grade 1 and 13% showed with K&L grade 2. On 6-year MRI, 55% of patients showed cartilage defect(s), 45% showed osteophyte(s), 36% showed subchondral cyst(s), 40% showed bone marrow oedema, 21% showed meniscal subluxation, 83% showed meniscal degeneration,11% showed effusion and 11% showed a Baker's cyst. Of these, most were significantly related with 6-year radiographic K&L grade, while only lateral cartilage defect(s), medial osteophyte(s) and medial meniscal subluxation were significantly related with persistent knee symptoms. 32% of patients showed new onset or progressive knee OA on 6-year MRI, for which age, history of non-traumatic knee symptoms and bone marrow oedema at baseline were independent prognostic factors.

CONCLUSIONS:
Degenerative knee abnormalities on MRI are related to the K&L score; however, not all abnormalities are reflected in clinical outcome. Age, history of non-traumatic knee symptoms and bone marrow oedema predict knee OA 6 years after knee trauma, present in 32% of the patients.