The Long-term Chondroprotective Effect of Meniscal Allograft Transplant: A 10- to 14-Year Follow-up Study

Background: The long-term chondroprotective effect of meniscal allograft transplant (MAT) and its superiority over meniscectomy have rarely been reported. Hypothesis: MAT would reduce osteoarthritis (OA) progression when compared with the meniscus-deficient knee. Graft extrusion distance would strongly affect the chondroprotective effect of the MAT. Study Design: Cohort study; Level of evidence, 3. Methods: A total of 17 knees receiving MAT were followed up as the MAT group. The MAT group was further divided into the nonextrusion subgroup (n = 9) and the extrusion subgroup (n = 8) according to 3-mm extrusion on the magnetic resonance imaging (MRI) coronal section. A further 26 consecutive patients receiving meniscectomy in the same period were followed up as the ME group. The healthy control group consisted of healthy contralateral legs chosen from the MAT and ME groups (n = 27). Joint space width (JSW) narrowing was measured on radiographs. Three-dimensional MRI with a T2 mapping sequence was used to quantitatively analyze cartilage degeneration and meniscal allograft extrusion in 5 directions (0°, 45°, 90°, 135°, and 180°). The cartilage degeneration index (CDI) was calculated according to the size and degree of the chondral lesions on MRI scans. The correlation between the CDI increase and the extrusion distance was analyzed. Results: The mean follow-up time was 11.3 years (range, 10-14 years). The MAT group had moderate superiority in chondral protection with less JSW narrowing (0.58 ± 0.66 mm) and CDI increase (1132 ± 1589) compared with the ME group (JSW narrowing: 1.26 ± 1.13 mm, P = .025; CDI increase: 2182 ± 1958, P = .079). The JSW narrowing (0.71 ± 0.80 mm; P = .186) and CDI increase (2004 ± 1965; P = .830) of the extrusion subgroup were close to those of the ME group, demonstrating that a 3-mm extrusion led to complete loss of the meniscal chondroprotective effect. The nonextrusion group had significantly less JSW narrowing (0.48 ± 0.48 mm; P = .042) and CDI increase (358 ± 249; P = .011) than the ME group. The JSW narrowing of the healthy control group was 0.22 ± 0.27 mm. The cartilage T2 values of the extrusion subgroup were similar to those of the ME group, with more OA features, whereas the T2 values of the nonextrusion subgroup were closer to those of the healthy control group. The extrusion distance in the 90° direction ( P = .002) and the follow-up time ( P = .019) significantly affected the CDI increase in the multivariate regression model. The average extrusion distance in the 45°, 90°, and 135° directions better predicted chondroprotection compared with the other individual directions. Conclusion: MAT had moderate advantages in chondroprotection compared with meniscectomy in the long term. Graft extrusion distance strongly affected the chondroprotective effect of MAT. The chondroprotective effect of the nonextruded meniscal allograft was close to that of the native meniscus, whereas the allografts with an extrusion >3 mm completely lost their function after meniscectomy.

Lateral Capsular Stabilization in Lateral Meniscal Allograft Transplantation

Background: Stabilization of the lateral capsule to the tibial plateau may decrease midbody extrusion after lateral meniscal allograft transplantation (MAT). However, there is a paucity of literature reporting on postoperative magnetic resonance imaging (MRI) findings after lateral capsular stabilization (LCS) at the time of lateral MAT. Purpose/Hypothesis: The purpose was to describe MRI findings after LCS and compare postoperative extrusion between isolated lateral MAT and lateral MAT with LCS. It was hypothesized that allograft extrusion would be reduced after MAT with LCS but that the stabilized capsule would increase the risk of tears to the capsule or allograft. Study Design: Cohort study; Level of evidence, 3. Methods: Included were patients who underwent lateral MAT with 6-month follow-up MRI. Concomitant LCS was performed for patients with redundant lateral capsule displaced from the lateral tibial plateau as evident on coronal MRI or arthroscopic examination (MAT+LCS group); otherwise, patients underwent MAT only (isolated MAT group). The Lysholm score, Tegner score, and lateral joint space on radiographs were compared between the 2 groups at 2 years postoperatively, and the stabilized lateral capsule and allograft were evaluated using 6-month follow-up MRI. Extrusion, rotation, and position of the allograft bridge were compared between the 2 groups. Regression analysis was performed to identify factors predictive of degree of extrusion. Results: There were 10 patients in the MAT+LCS group and 13 patients in the isolated MAT group. No significant differences were found between groups in preoperative patient characteristics or postoperative Lysholm score, Tegner score, lateral joint space, or MRI parameters. Postoperative extrusion was not related to obliquity angle, position of the bony bridge, or presence of LCS. In the MAT+LCS group, 1 patient showed a tear of the lateral capsule and a radial tear of the allograft, and 3 patients had a meniscocapsular separation at the midbody of the allograft. In the isolated MAT group, 1 patient had a peripheral tear at the midbody, but there was no tear of the allograft in the other patients. Conclusion: LCS did not decrease extrusion of lateral meniscal transplantation, but it can lead to increased risk for graft or capsule tear.

Securing Transplanted Meniscal Allografts Using Bone Plugs Results in Lower Risks of Graft Failure and Reoperations: A Meta-analysis

Background: Meniscal allograft transplant (MAT) is an important treatment option for young patients with deficient menisci; however, there is a lack of consensus on the optimal method of allograft fixation. Hypothesis: The various methods of MAT fixation have measurable and significant differences in outcomes. Study Design: Meta-analysis; Level of evidence, 4. Methods: A single-arm meta-analysis of studies reporting graft failure, reoperations, and other clinical outcomes after MAT was performed. Studies were stratified by suture-only, bone plug, and bone bridge fixation methods. Proportionate rates of failure and reoperation for each fixation technique were pooled with a mixed-effects model, after which reconstruction of relative risks with confidence intervals was performed using the Katz logarithmic method. Results: A total of 2604 patients underwent MAT. Weighted mean follow-up was 4.3 years (95% CI, 3.2-5.6 years). During this follow-up period, graft failure rates were 6.2% (95% CI, 3.2%-11.6%) for bone plug fixation, 6.9% (95% CI, 4.5%-10.3%) for suture-only fixation, and 9.3% (95% CI, 6.2%-13.9%) for bone bridge fixation. Transplanted menisci secured using bone plugs displayed a lower risk of failure compared with menisci secured via bone bridges (RR = 0.97; 95% CI, 0.94-0.99; P = .02). Risks of failure were not significantly different when comparing suture fixation to bone bridge (RR = 1.02; 95% CI, 0.99-1.06; P = .12) and bone plugs (RR = 0.99; 95% CI, 0.96-1.02; P = .64). Allografts secured using bone plugs were at a lower risk of requiring reoperations compared with those secured using sutures (RR = 0.91; 95% CI, 0.87-0.95; P < .001), whereas allografts secured using bone bridges had a higher risk of reoperation when compared with those secured using either sutures (RR = 1.28; 95% CI, 1.19-1.38; P < .001) or bone plugs (RR = 1.41; 95% CI, 1.32-1.51; P < .001). Improvements in Lysholm and International Knee Documentation Committee scores were comparable among the different groups. Conclusion: This meta-analysis demonstrates that bone plug fixation of transplanted meniscal allografts carries a lower risk of failure than the bone bridge method and has a lower risk of requiring subsequent operations than both suture-only and bone bridge methods of fixation. This suggests that the technique used in the fixation of a transplanted meniscal allograft is an important factor in the clinical outcomes of patients receiving MATs.

Clinical Outcomes of Meniscal Allograft Transplantation With Respect to the Minimal Clinically Important Difference

Background: Arthroscopic-assisted meniscal allograft transplantation (MAT) has become a viable and effective treatment option for young active patients with postmeniscectomy pain. The minimal clinically important difference (MCID) of patient-reported outcome measures (PROMs) is imperative to evaluate the clinical significance of surgical interventions and inform clinical practice guidelines in orthopaedic surgery. Purpose: To perform a systematic review of clinical outcome studies of patients undergoing MAT and compare postoperative improvement with established MCID thresholds. Study Design: Systematic review and meta-analysis; Level of evidence, 4. Methods: A systematic review was performed using the PubMed, Web of Science, and Cochrane Library databases. A meta-analysis was performed using data obtained from studies reporting patient-reported outcomes. Subgroup analysis was performed on patients undergoing isolated lateral MAT using fresh-frozen grafts. Weighted mean postoperative improvements in the International Knee Documentation Committee (IKDC), Lysholm, and visual analog scale for pain (VAS pain) were calculated and compared with MCID values to determine if they met the MCID threshold. Results: A total of 35 studies were identified, including 1658 unique patients. Weighted mean postoperative score improvements exceeded MCID thresholds for the VAS pain, IKDC, and Lysholm. Subgroup analysis of patients undergoing isolated lateral fresh-frozen MAT demonstrated postoperative improvements exceeding the MCID for the Lysholm and VAS pain. Conclusion: Evaluating postoperative PROMs with respect to the MCID is crucial to evaluate the effect of MAT on functional improvement. The results of the present meta-analysis suggest that postoperative improvements after MAT are clinically meaningful as reflected by PROMs exceeding the MCID threshold for the IKDC, Lysholm, and VAS pain.