Articular Cartilage Degenerates After Subtotal/Total Lateral Meniscectomy but Radiographic Arthrosis Progression Is Reduced After Meniscal Transplantation.

BACKGROUND: Little is known about the degree of articular cartilage degeneration after subtotal/total lateral meniscectomy in patients who later undergo isolated lateral meniscal allograft transplantation (LMAT). It has not yet been studied whether arthritic changes as shown on radiographs were lower during the posttransplantation period than during the meniscus-deficient period.

HYPOTHESIS: Articular cartilage will significantly degenerate during the meniscus-deficient period, but the progression in radiographic arthrosis is reduced after LMAT.

STUDY DESIGN: Case series; Level of evidence, 4.

METHODS: This study retrospectively reviewed 49 patients who underwent subtotal/total lateral meniscectomy before isolated LMAT performed over 1 year later by the same surgeon. International Cartilage Repair Society (ICRS) grades of the femorotibial joint at the time of subtotal/total meniscectomy and at LMAT were compared. Radiographic evaluation was performed at the time of initial meniscectomy, LMAT, and the latest follow-up in 38 patients (after 11 patients whose radiographs showed incomplete ossification at the time of meniscectomy were excluded). Arthrosis, based on Kellgren-Lawrence (K-L) grades, was determined on standing anteroposterior views. Joint space width (JSW) was measured on weightbearing flexion posteroanterior views.

RESULTS: Over a mean meniscus-deficient period of 4.5 years (range, 1-13 years), articular cartilage significantly degenerated on the femoral and tibial sides (P < .001). Grade ≥3 degeneration on the lateral tibial plateau was observed in 13 patients (27%) at the time of initial meniscectomy; this incidence doubled to 28 patients (57%) by the time of LMAT. The K-L grades worsened (P < .001) and JSWs narrowed significantly (-0.65 ± 1.09 mm; P = .001) during the mean meniscus-deficient period of 3.1 years. At radiographic assessment, however, the K-L grades (P = .097) and JSWs (4.06 ± 1.19 vs 3.92 ± 1.21 mm; mean difference, -0.14 ± 0.68 mm; P = .213) did not significantly change during the mean posttransplantation period of 3.8 years. The changes in ICRS grade and JSW during the meniscus-deficient period were not associated with age, body mass index, mechanical axis deviation, or Tegner activity level (P > .05 for all relationships).

CONCLUSION: Patients who underwent isolated LMAT showed substantial articular cartilage degeneration at the time of initial subtotal/total lateral meniscectomy, and this degeneration progressed thereafter. Further progression of radiographic arthrosis was delayed after LMAT.