Results of isolated lateral meniscus allograft transplantation: focus on objective evaluations with magnetic resonance imaging.

BACKGROUND

Although numerous studies have reported outcomes of meniscus allograft transplantation, only a few dealt with isolated procedures or employed objective evaluation methods.

HYPOTHESIS

Isolated lateral meniscus allograft transplantation (LMAT) provides clinical improvements and favorable objective results in symptomatic lateral meniscus-deficient knees.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

The authors collected and analyzed the results of 29 consecutive isolated LMATs with a minimum of 24 months' follow-up. The mean age of the patients was 29.6 years (range, 18-48 years). The modified Lysholm scoring system and the Hospital for Special Surgery score were used to evaluate subjective improvements. Every patient underwent postoperative magnetic resonance imaging (MRI) or second-look arthroscopy or both as objective evaluation. The allograft extrusion and relative percentage of extrusion (RPE) was measured on final MRI. Status of the allograft was classified according to the above 3 categories into 3 grades; satisfactory, fair, or poor.

RESULTS

The average length of follow-up was 53.6 months. Symptoms and functions of the involved knee improved in 28 knees (96.6%) at the last follow-up. The average preoperative modified Lysholm score was 69.5, which increased to 89.9 postoperatively (P < .001). The average preoperative Hospital for Special Surgery pain score was 15.3, which increased to 26.7 postoperatively (P < .001). Postoperative MRI alone was performed in 22 knees (75.9%), second-look arthroscopy alone in 1 knee (3.4%), and both examinations in 6 knees (20.7%). The MRI scans revealed 4 gross and 5 small tears in the allograft and also provided valuable information despite magnetic susceptibility artifacts. Mean allograft extrusion was 4.0 mm and mean RPE was 45.4%. At second-look arthroscopy, 3 gross tears and a small flap tear were identified in 4 cases. According to the clinical and the objective criteria, the allografts were graded as satisfactory in 20 cases (69.0%), fair in 5 cases (17.2%), and poor in 4 cases (13.8%).

CONCLUSION

The results of the present study showed remarkable symptomatic improvements and acceptable objective findings in short- to intermediate-term follow-up. Even in cases with favorable clinical results, MRI or second-look arthroscopy was necessary to identify the actual status of the allograft. Isolated LMAT could be an effective treatment for symptomatic, lateral meniscus-deficient knees.