Delayed Rehabilitation After Lateral Meniscal Allograft Transplantation Can Reduce Graft Extrusion Compared With Standard Rehabilitation

Meniscal extrusion prevention would be important for restoring normal knee kinematics, even though the effect of graft extrusion after meniscal allograft transplantation (MAT) has not been clearly identified. When compared with standard rehabilitation protocols, delayed rehabilitation after lateral MAT could reduce graft extrusion. Cohort study; Level of evidence, 3. A total of 53 patients who underwent lateral MAT with the keyhole technique from June 2011 to March 2015 were included. Graft extrusion and lateral compartment articular cartilage loss on magnetic resonance imaging, joint space width (JSW) on weightbearing radiographs, and clinical outcomes (including subjective scores and functional tests) of 25 patients who underwent standard rehabilitation (group S) after lateral MAT were compared with those of 28 patients who underwent delayed rehabilitation (group D), which included immobilization during the first 3 weeks and use of unloading braces for 9 weeks. Mean ± SD follow-up times for groups S and D were 25.7 ± 6.4 and 24.5 ± 7.1 months, respectively. Although the postoperative clinical outcomes did not differ between the groups, graft extrusion (3.2 ± 1.5 mm vs 1.8 ± 1.6 mm) and relative percentage of extrusion (32.2% ± 14.6% vs 17.3% ± 16.6%) were greater in group S than in group D (P < .001 for both). The percentage of patients with graft extrusion (≥3 mm) was 52% in group S and 21.4% in group D. JSWs on Rosenberg view decreased by 0.1 mm in group S but increased by 0.3 mm in group D (P = .035). Kellgren-Lawrence grade and modified Outerbridge grade progressed by 44% and 44% among patients in group S and by 17.9% and 21.4% among patients in group D, respectively. There were significant correlations between the coronal graft extrusion and postoperative JSWs on full extension (–0.452) and Rosenberg (–0.410) views, Kellgren-Lawrence grade (0.727), and modified Outerbridge grade (0.732) on magnetic resonance imaging (P < .001 for all). Compared with standard rehabilitation, delayed rehabilitation showed less coronal graft extrusion and joint space narrowing on weightbearing and reduced the progression of arthrosis, although the rehabilitation protocols showed no differences in clinical outcomes