Lateral Meniscal Allograft Transplantation Provides a Chondroprotective Effect on Articular Cartilage: Quantitative 3-T Magnetic Resonance Imaging T2 Mapping

Lateral Meniscal Allograft Transplantation Shows a Long-Term Chondroprotective Effect on Quantitative Magnetic Resonance Imaging T2 Mapping at 7-Year Minimum Follow-Up

PURPOSE

To assess the long-term chondroprotective effect of lateral meniscal allograft transplantation (MAT) using quantitative magnetic resonance imaging (MRI) T2 mapping.

METHODS

In patients who underwent isolated lateral MAT, quantitative MRI T2 mapping was conducted preoperatively and postoperatively with at minimum follow-up of 7 years to assess the articular cartilage status. On the sagittal section image bisecting the lateral femoral condyle, the weight-bearing portions of the femoral and tibial articular cartilage were divided into 3 segments each-6 segments in total-based on the meniscal coverage area. The regions-of-interest analyses were performed on the 6 segments to measure the mean T2 value. Then the whole layer was divided into deep and superficial layers for further zonal analysis. The longitudinal change in T2 values was statistically analyzed using paired t-tests. Clinical outcome was evaluated using the Lysholm score.

RESULTS

A total of 31 patients were included in the study, with the MRI follow-up period of a minimum of 7 years (mean: 8.9 ± 1.3 years; range: 7.0-11.2 years). The mean T2 value of the whole layer showed significant improvement in all segments of the femoral cartilage and the posterior segment of tibial cartilage. In the zonal analysis, the mean T2 value of the tibial cartilage showed significant improvement in the superficial layer of the mid to posterior portion, while the deep layer remained stable. In contrast, the mean T2 value of the femoral cartilage showed significant improvement in the superficial and deep layers in all segments. The mean Lysholm score significantly improved from 62.6 ± 12.8 to 90.9 ± 10.5 (P < .001).

CONCLUSIONS

This study suggests that MAT appears to have a long-term chondroprotective effect on the articular cartilage as judged by quantitative T2 mapping.

LEVEL OF EVIDENCE

Level Ⅳ, case series.

Editorial Commentary: Meniscal Allograft Transplantation Results in Both Pain Relief and Chondroprotection

Meniscal allograft transplantation (MAT) effectively alleviates symptoms of the meniscus deficiency. Thus, MAT is a widely accepted and recommended treatment for individuals with unicompartmental pain due to meniscus deficiency. Long-term follow-up studies have indicated that MAT yields favorable clinical outcomes, demonstrating high survivorship and low rates of serious complications. In addition, the ability of MAT to function akin to the native meniscus and shield the knee cartilage from osteoarthritis has been a subject of ongoing investigation, and recent direct magnetic resonance imaging evidence shows long-term chondroprotection following MAT. Cartilage lesions worsen during the meniscus deficiency period. Consequently, delaying MAT until patients become more symptomatic may lead to poor outcomes and low graft survivorship due to concomitant cartilage lesions. These findings prompt a reevaluation of the purpose and timing of MAT decisions for meniscectomy patients, suggesting a more proactive approach to recommending MAT, particularly for patients at high risk of postmeniscectomy syndrome and osteoarthritis progression.

Survivorship of 157 Arthroscopic Meniscal Allograft Transplants Using Bone Fixation at a Mean of 7 Years and Prognostic Factors Analysis

BACKGROUND

Meniscal allograft transplantation (MAT) is an accepted and effective treatment option in the context of unsalvageable menisci, particularly in young and active patients. It has been shown to reduce pain and improve knee function in previously symptomatic patients. However, there is still limited knowledge about the long-term survival rates of allografts, the durability of clinical results, and the influence of patient-specific parameters, such as leg alignment, tibial slope, and preoperative International Cartilage Regeneration & Joint Preservation Society (ICRS) grade.

PURPOSE

To determine (1) the long-term clinical success rate after MAT with bony fixation in a large, single-center cohort of consecutive patients, and (2) if patient-specific and procedural variables influence the clinical, anatomic, and subjective outcomes and risk of failure.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Data on 185 consecutive knees undergoing MAT in a single institution were prospectively collected and screened for inclusion in this study. The minimum follow-up time was 2 years. Radiographic variables (ICRS grade and Kellgren-Lawrence grade) were assessed preoperatively and at follow-up. Subjective patient-reported outcome measures (PROMs) (Lysholm score, Knee injury and Osteoarthritis Outcome Score [KOOS] including subscores, International Knee Documentation Committee [IKDC] score, and visual analog scale [VAS] score) were collected preoperatively and at follow-up. Clinical failure was defined as revision surgery due to graft failure or conversion to total knee arthroplasty. Anatomic failure was considered a tear covering >20% of the allograft, any peripheral tear, and unstable peripheral fixation leading to dislocation of the graft. Subjective failure was defined as Lysholm score ≤65. Preoperative tibial slope and leg alignment were assessed. Survival analyses were performed using the Kaplan-Meier estimate. Univariate and multivariate analyses were performed to determine risk factors for clinical and anatomic failure.

RESULTS

A total of 157 knees met inclusion criteria. After a mean follow-up time of 7 ± 3.5 years, 127 (80.9%) knees were free of clinical, anatomic, and subjective failure. Fourteen (8.9%) knees experienced clinical failure, 26 (16.6%) knees were identified as having experienced anatomic failure, and 13 (8.3%) patients experienced subjective failure with a reported Lysholm score of ≤65 at a mean follow-up of 7 years. Concurrent osteochondral allograft transplantation was identified as a predictor of both clinical (hazard ratio [HR], 4.55; 95% CI, 1.46-14.17; P = .009) and anatomic (HR, 3.05; 95% CI, 1.34-6.92; P = .008) failure. Cartilage damage of ICRS grade 3 or 4 of the index compartment conveyed an increased risk for clinical (HR, 3.41; 95% CI, 1.05-11.01; P = .04) and anatomic (HR, 3.04; 95% CI, 1.31-7.11; P = .01) failure. High-grade cartilage damage preoperatively (HR, 10.67; 95% CI, 1.037-109.768; P = .046), patient age >25 years (HR, 5.44; 95% CI, 0.120-246.070; P = .384), and a body mass index >30 (HR, 2.24; 95% CI, 0.748-6.705; P = .149) were associated with subjective failure. PROMs including KOOS and IKDC were significantly improved at final follow-up compared with preoperative scores across all measurements (P < .005).

CONCLUSION

MAT showed good to excellent clinical results at a mean follow-up of 7 years. Low ICRS lesion grade was associated with a higher clinical and anatomic survival rate. Patients with concurrent OCA transplantation are at a higher risk of clinical and anatomic failure, but still report significantly improved PROMs. These results suggest that MAT has a lasting beneficial effect both in isolation and in complex cases with ≥1 concurrent procedures.

Meniscal allograft transplantation improves patient-reported outcomes in both minimal and moderate knee osteoarthritis at 1 and 2 years postoperatively

PURPOSE

Severe cartilage damage and advanced knee osteoarthritis (OA) might be associated with poor outcomes of meniscal allograft transplantation (MAT). The purpose of this prospective follow-up study was to explore MAT survivorship and patient satisfaction among young patients with symptomatic meniscal deficiency and radiological OA of different Kellgren-Lawrence (K-L) grades.

METHODS

Thirty-five consecutive MAT patients were prospectively followed up for 2 years. The lateral meniscus was replaced in 29 patients and the medial meniscus in 6 patients. Outcomes were assessed using the KOOS4 composite score, KOOS subscales, Lysholm knee score, and OA K-L grade progression from weight-bearing knee radiographs. For the outcome analysis, patients were categorized into two groups: 19 in Group A (K-L classification 0-1) and 16 in Group B (K-L classification 2).

RESULTS

In terms of KOOS4 and Lysholm scores, the patients showed a clinically significant improvement from baseline to the 1-year follow-up (22.2 points, 95% CI 16.6-27.8 for KOOS4 and 16.8 points, 95% CI 8.9-24.6 for Lysholm), and the improvement remained at 2 years (20.6 points, 95% CI 13.2-28.1 for KOOS4 and 21.5, 95% CI 12.5-30.7 for Lysholm). At the 6-month follow-up, this improvement was not yet observed. Minor between-group differences were observed in the KOOS4 and Lysholm scores for the K-L 0-1 and K-L 2 OA groups, but the estimates were imprecise with wide confidence intervals. A clinically relevant difference between these two study groups could not be found at any timepoint. The reoperation rate was higher in the K-L 2 group than in the K-L 0-1 group (31% vs. 11%).

CONCLUSIONS

MAT yielded improved patient-reported outcomes and subjective satisfaction at 1 and 2 years postoperatively. The differences from baseline exceeded the minimal clinically important difference (MCID) at all timepoints. The severity of cartilage damage and knee OA in terms of the K-L grade at the time of surgery did not affect the KOOS and Lysholm scores after the MAT procedure. Knee OA progression in terms of K-L grade worsening was not observed in any patients.

LEVEL OF EVIDENCE

III.

In situ observation of cartilage matrix based on two-photon fluorescence microscopy

Articular cartilage lesions remain a major challenge for clinicians and researchers. Several techniques, such as histological scoring, magnetic resonance imaging, and tissue section staining, are available for detecting cartilage degeneration and lesions and evaluating cartilage repairs. Nevertheless, these methods are complex and have numerous influencing factors, which may present obstacles to efficient communication between studies. In this study, we developed a fluorescence observation system that integrated a two-photon laser scanning confocal microscope (TPLSCM) with the second-harmonic generation (SHG) of a cartilage matrix. The observation system enabled the detection of autofluorescence emitted by the cartilage matrix without species specificity, facilitating both qualitative and quantitative analyses of the cartilage matrix. Notably, this observation could be applied three-dimensionally to a fresh specimen in situ up to a depth of 300 μm, obviating the need for traditional histological fixation, slicing, or staining. Furthermore, using this observation system, we reconstructed a three-dimensional (3D) image and a 3D model of the cartilage matrix. The utilization of the 3D fluorescence model may serve as a dependable option for the fabrication of cartilage matrix biomimetic scaffolds in future studies.