Purpose: This study aimed to investigate the long-term outcomes of arthroscopic partial meniscectomy for medial meniscus tear (with intact posterior root) and to analyze the risk factors for treatment failure.
Methods: The records of 165 patients who underwent partial meniscectomy for medial meniscus tear with intact posterior root with a minimum 5-year follow-up were included. Modified Lysholm score and radiologic outcomes were compared between preoperative and latest follow-up periods. The cumulative Outerbridge grade of the medial compartment was defined as follows: 0-4, low chondral wear; 5-6, intermediate wear; or 7-8, high wear. Kaplan-Meier survival and Cox hazard regression analyses were performed to assess the survivorship after partial meniscectomy. Conversion to total knee replacement arthroplasty, high tibial osteotomy or a Lysholm score of < 65 points indicated treatment failure.
Results: Mean Lysholm score improved from 66.3 ± 14.2 preoperatively to 81.8 ± 17.9 at the latest follow-up (p = 0.001). The postoperative 10-year survival rate of the low chondral wear group [97% (95% confidence interval (CI) 141.7-152.6 months)] was higher than that of the intermediate [83.1% (95% CI 129.6-147.9 months)] and high wear groups [76.1% (95% CI 115.2-135.0 months)]. A 1 mm joint space width narrowing led to a 37.7% increase in the failure rate [B = - 0.473; hazard ratio, 0.623 (95% CI 0.423-0.917); p = 0.016]. The high chondral wear group showed a higher failure rate compared to the low wear group [B = 1.870; hazard ratio, 6.488 (95% CI 0.853-49.333); p = 0.041].
Conclusion: Partial meniscectomy offers pain relief and functional improvement for medial meniscus tear with intact posterior root. Preoperative joint space narrowing and higher chondral wear at surgery were significant risk factors of treatment failure. Partial meniscectomy should be considered as an effective treatment for irreparable medial meniscus tear with intact posterior root without joint space narrowing and chondral wear.
Level of evidence: Case series, Level IV.
Keywords: Arthritis; Medial meniscus; Partial meniscectomy; Survivorship.