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Background: Meniscus allograft transplantation (MAT) is useful for meniscus-deficient knees. Although meniscal extrusion is common after MAT, there is no consensus regarding the criteria for normal meniscal extrusion or the relationship between clinical and radiologic results.

Hypothesis: Meniscal extrusion after MAT results in poor clinical, radiologic, and arthroscopic outcomes.

Study Design: Case series; Level of evidence, 4.

Methods: Thirty-six of 60 patients undergoing MAT from September 2002 to June 2007 who were available for follow-up evaluation for more than 2 years were evaluated. The study population (31 men, 5 women) consisted of 15 and 21 cases of medial and lateral meniscus transplant, respectively. Knee status was evaluated by Lysholm score, plain radiography, and magnetic resonance imaging preoperatively and postoperatively. Second-look examinations were performed in 18 cases.

Results: Mean follow-up was 31.4 months (range, 24-36). Lysholm knee score increased significantly (mean, 88.2; range, 70-100) on final visit versus the preoperative value (mean, 61.2; range, 26-83; P < .001). Joint-space narrowing was 0.08 mm (range, –2.58 to 1.92) in extension AP and –0.09 mm (range, –2.3 to 1.8) in Rosenberg view. Kellgren-Lawrence arthrosis grade did not change in 28 knees (77.8%) and progressed by 1 grade in 8 knees. Meniscal extrusion extent was 3.87 ± 1.94 mm and relative percentage extrusion was 42.1% ± 17.7%. Seven cases (19.4%) showed minor extrusion (<3 mm), 27 (75%) showed major extrusion (>3 mm), and 2 (5.6%) showed no extrusion. Further degeneration was absent in 28 knees (77.8%) on magnetic resonance imaging. In second-look arthroscopic examinations at an average of 26.3 months, 11 of 18 (63.6%) cases showed no progression of cartilage degeneration. There was no significant correlation between meniscal extrusion and other parameters.

Conclusion: This study indicated that MAT can improve the clinical status of the meniscectomized knee. Although meniscal extrusion occurred after surgery in most cases, there was no significant correlation with various clinical, radiologic, or arthroscopic outcomes. Further studies are required to evaluate long-term effects of meniscal extrusion.

Background: Quantifying changes in meniscal volume in vivo before and after partial meniscectomy (PM) could help elucidate the mechanisms involved in osteoarthritis development after meniscal injury and its surgical treatment.

Purpose/Hypothesis: To determine whether quantitative magnetic resonance imaging (qMRI) can detect the immediate reduction in meniscal volume created by PM, while ruling out changes in unresected structures. We hypothesized that qMRI would be reliable for determining meniscal volume within the repeated images of unresected menisci. Additionally, we expected no significant difference in volume between the uninjured menisci of the injured knees and the same menisci of the uninjured knees.

Study Design: Cohort study (Diagnosis); Level of evidence, 2.

Methods: Ten subjects with meniscal tears were evaluated with 3-T MRI before and after arthroscopic PM. Manual segmentation was used to create models of the menisci and to determine the preoperative and postoperative meniscal volumes for each subject. The responsiveness and reliability of qMRI for determining meniscal volume in vivo were evaluated using these measurements. We expected a decrease in volume of the resected menisci, but not in the uninjured menisci, after surgery.

Results: The mean preoperative volume of the injured menisci was significantly greater than the mean postoperative volume (2896 ± 277 vs 2480 ± 277 mm³; P = .000). There was no significant difference between the mean preoperative and postoperative volumes of the uninjured menisci (2687 ± 256 vs 2694 ± 256 mm³; P = 1.000).

Conclusion: Manual segmentation demonstrated a significant reduction in the volume of the surgically resected menisci after PM, but no significant change in the volume of unresected meniscal tissue, indicating that the manual segmentation method is responsive.

Clinical Relevance: This approach offers a novel, reliable method to study the relationship between the volume of meniscal tissue removed during PM and subsequent patient outcomes during long-term clinical studies.