Influence of Concomitant Meniscal Allograft Transplantation on Midterm Outcomes After Osteochondral Allograft Transplantation: A Comparative Matched-Pair Analysis.

BACKGROUND: Osteochondral allograft transplantation (OCAT) is an accepted knee joint-preserving treatment strategy for focal osteochondral lesions that is often conducted in combination with meniscal allograft transplantation (MAT). Despite its frequent and simultaneous utilization, there remains a lack in the literature reporting on outcomes and failure rates after concomitant procedures. PURPOSE: To determine (1) the midterm clinical success rate after OCAT+MAT in comparison with a matched-pair cohort undergoing isolated OCAT, (2) whether patient-specific and procedural variables influence the risk of failure, and (3) patient-reported outcome measures over time. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A single-center matched-pair cohort study was conducted investigating outcomes in patients who underwent OCAT of the medial or lateral femoral condyle with and without MAT between 2004 and 2020. Patients were matched 1:1 by age (±5 years), sex (male or female), body mass index (±5), and grouped Kellgren and Lawrence grade (grades 0-1 or 2-4). The minimum follow-up time was 2 years. Radiographic variables (International Cartilage Regeneration & Joint Preservation Society [ICRS] grade and Kellgren and Lawrence grade) were assessed preoperatively and at follow-up. Subjective patient-reported outcome measures (Lysholm score, Knee injury and Osteoarthritis Outcome Score [KOOS] including subscores, International Knee Documentation Committee [IKDC] score, and visual analog scale score) were collected preoperatively and at follow-up. Clinical failure was defined as revision surgery for graft failure or conversion to total knee arthroplasty. Patient-reported, clinical, and radiographic outcomes were compared between groups. RESULTS: In total, 66 patients (33 treated with isolated OCAT, 33 treated with OCAT+MAT; 57.6% male) with a mean age of 26.3 years (range, 18-62 years) were followed for a mean of 5.6 years (minimum, 2 years; range, 24-218 months). The 2 cohorts showed no difference in Kellgren and Lawrence grade postoperatively (P = .59). There was a significantly higher ICRS grade detected at follow-up in the OCAT+MAT group (2.81 ± 1.10) compared with the OCAT group (2.04 ± 0.96) (P < .05). There were no statistically significant differences between the groups regarding reoperation rate (OCAT: n = 6; OCAT+MAT: n = 13; P = .116), time to reoperation (OCAT: 46.67 ± 47.27 months vs OCAT+MAT: 28.08 ± 30.16 months; P = .061), and failure rate (OCAT: n = 4 [12.1%] vs OCAT+MAT: n = 5 [15.2%]; P = .66). In the OCAT+MAT group, an increase of tibial slope by 1° conferred a 1.65-fold increase in the hazard for failure over decreased slope (hazard ratio, 1.65; 95% CI, 1.10-2.50; P < .05). The overall survival rate was 86% at a mean follow-up of 5.6 years. Patient-reported outcome scores were significantly improved at the final follow-up compared with preoperative status. No significant differences were seen between groups with respect to subjective IKDC, Lysholm, Tegner, and KOOS results, except for the KOOS Symptoms subscale score, which was significantly higher in the OCAT+MAT group than in the OCAT group (mean difference, 14.6; P < .05) and did exceed the minimal clinically important difference threshold of 10.7. CONCLUSION: Midterm results after isolated OCAT and OCAT+MAT show high rates of healing and sustainable subjective improvement of knee function and quality of life. However, it should be noted that the difference in reoperation rate and time to reoperation between the groups is arguably clinically important and that lack of statistical significance may be because of low power. These results imply that isolated OCAT is an efficient joint-preserving treatment that can be combined with MAT in well-selected patients with meniscal insufficiency without negative influence on global clinical outcomes.

Correlation between articular cartilage status on outcomes and survivorship following meniscal allograft transplantation: A systematic review.

PURPOSE: To conduct a systematic review evaluating potential correlations between preoperative articular cartilage integrity on outcomes and survivorship in patients undergoing meniscal allograft transplantation (MAT). METHODS: A literature search was performed by querying SCOPUS, PubMed, Medline, and the Cochrane Central Register for Controlled Trials from database inception through May 2023 according to the 2020 PRISMA statement. Inclusion criteria were limited to studies reporting on outcomes and survivorship following MAT based on preoperative cartilage status. RESULTS: Sixteen studies, consisting of 1723 patients (n = 1758 total menisci), were identified in six level III and 10 level IV evidence studies. There was high heterogeneity in cartilage grading scales, reporting of concomitant cartilage procedures, and indications for MAT based on osteoarthritis. Patients with lower limb malalignment were either excluded or corrected with an osteotomy. MAT failure rate was reported in nine studies, with four studies reporting a greater rate of failure in knees with higher degrees of cartilage damage. Eight studies reported on clinical outcomes based on cartilage grade, with two studies reporting significant differences in clinical outcomes based on cartilage grade. Of the five studies reporting management of full-thickness chondral defects with cartilage surgery, three studies reported no significant difference in survivorship based on preoperative cartilage grade, while one study reported lower survivorship and one study reported unclear results. No studies found significant differences in survivorship and outcomes between medial and lateral MAT. CONCLUSIONS: Conflicting results and high variability in reporting of concomitant cartilage repair and indications for MAT exist in studies evaluating the efficacy of MAT based on articular cartilage status. The degree of preoperative chondral damage did not have a strong relationship with clinical outcomes following MAT. Higher degrees of cartilage damage were associated with higher MAT failure rates, with possible improvement in survivorship when treated with an appropriate cartilage procedure. LEVEL OF EVIDENCE: Level IV.

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.

Editorial Commentary: High-Grade Cartilage Lesions Require Treatment to Prevent Meniscal Allograft Transplant Failure.

In patients with symptomatic high loss of meniscal volume and function due to irreparable tears, meniscal allograft transplantation may result in symptom relief and ideally prevent long-term consequences of articular cartilage degeneration and osteoarthritis. However, the degree of cartilage damage at the time of meniscal allograft transplantation is associated with graft failure, and untreated high-grade cartilage lesions increase the risk. Correction of femorotibial malalignment is also essential.

Editorial Commentary: Polyurethane Meniscal Scaffold Could Serve as a Bridge to Meniscal Allograft or Arthroplasty in Carefully Selected Post-Meniscectomy Patients.

The young, active patient with pain after subtotal meniscectomy represents a troubling clinical situation with limited treatment options. "Post-meniscectomy syndrome" occurs at a rate of 4-25% and is defined as the presence of knee pain and functional limitations due to increased contact stresses and overload of the articular cartilage in a knee compartment, after subtotal or total meniscectomy. Meniscal allograft transplantation (MAT) can have reasonable results for some patients, typically under the age of 50, with no degenerative change, and no, or correctable instability or malalignment. However, MAT is expensive, it is often difficult to access meniscal allograft tissue, and the procedure can be technically challenging for the surgeon. Meniscal scaffolds have been commercially available and examined in small studies in the literature and metanalyses since the early 2000s. Generally, patients have shown clinical improvement with their use, but over time, they have shown signs of radiologic failure (decrease in size of the meniscal scaffold, meniscal extrusion on MRI, or other radiographic changes.) Nonetheless, recent research shows long-term survivorship of a polyurethane scaffold in some, carefully selected patients. While not shown to be chondroprotective, this could serve as a bridge to MAT or arthroplasty.

Editorial Commentary: Meniscal Allograft Transplantation Is Effective for Adolescents With Meniscal Insufficiency, Although Outcomes May Decline Over Time.

Over the last several years, there has been a shift from arthroscopic partial meniscectomy to meniscal repair, especially in the younger patient. In case of a necessary partial meniscectomy, some patients have unremittent symptoms of pain and effusion corresponding to the postmeniscectomy syndrome. In these patients without large coronal malalignment, meniscal allograft transplantation is a valuable option to restore contact pressures, promote a chondroprotective microenvironment, and potentially delay secondary surgical interventions symptoms. In the adolescent population, meniscal allograft transplantation has been shown to effectively improve patient-reported outcomes with a low conversion to arthroplasty. However, these treatments are far from ideal, and prevention is certainly better than the cure: timely diagnosis of meniscus injuries, appropriate treatment with meniscus repair rather than partial meniscectomy, even in the complex tear patterns, and consideration of corrective osteotomy for milder cases of malalignment.

Risk Factor for Clinical Failure of Medial Meniscal Allograft Transplant: Early vs Late Graft Tear.

BACKGROUND: Graft tears are common postoperative findings in meniscal allograft transplant (MAT). Graft tear in medial MAT may be different from that of lateral MAT, considering the difference between medial meniscal tears and lateral meniscal tears. Moreover, medial MAT is frequently accompanied by ligament reconstruction, which is associated with graft tear. The effect of graft tear on the long-term survivorship of medial MAT has not been investigated. HYPOTHESIS: Graft tear would adversely affect the survivorship of medial MAT and the effect would be different according to the timing of graft tear. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 55 patients undergoing medial MAT between June 2019 and March 2000 were retrospectively reviewed. Postoperative magnetic resonance imaging (MRI) scans were reviewed to identify graft tears, and the timing of their occurrence was investigated. Postoperative MRI was performed routinely during the first postoperative year and every 2 years thereafter. The patients were classified into a no graft tear (NT) group, early graft tear (occurring within 1 year; ET) group, and late graft tear (occurring 1 year after surgery; LT) group. The survival rate of medial MAT was estimated according to graft tear, with a failure being defined as (1) reoperations including arthroplasty, realignment osteotomy, revision MAT, and meniscectomy (>50% of the graft or to the zone of the meniscocapsular junction) or (2) Lysholm score <65. Clinical scores were compared between the groups. RESULTS: The mean follow-up duration was 8.6 ± 5.3 years. During that period, clinical failures occurred in 6 (10.9%) patients. The overall survival rate at 5 years was 94.0% (95% CI, 90.6%-97.4%). Graft tears were seen in 18 patients: 6 patients in the ET group and 12 patients in the LT group. The median time when the graft tear was noted on MRI scans was 5.5 months (range, 1-11 months) postoperatively in the ET group and 99.5 months (range, 19-264 months) postoperatively in the LT group. Five patients in the ET group had root tears, whereas 9 patients in the LT group had complex or horizontal tears. The 5-year survival rate of the ET group was 62.5% (95% CI, 41.2%-83.8%), which was significantly lower than that of the NT group (96.8%; 95% CI, 93.6%-99.9%) and the LT group (85.7%; 95% CI, 72.5%-98.9%; P = .002). The mean postoperative Lysholm scores were 85.6 ± 17.9 in the NT group, 93.0 ± 2.8 in the ET group, and 79.3 ± 11.6 in the LT group, showing no significant difference between the groups (Kruskal-Wallis test, P = .058). CONCLUSION: Clinical relevance of graft tear that occurred after medial MAT was dependent upon its timing. ET was a risk factor for clinical failure, whereas LT did not adversely affect graft survivorship. Lysholm scores did not differ according to graft tear.

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.

Editorial Commentary: Tissue-Engineered Meniscal Scaffolds and Implants Show Promising Short-Term Outcomes While Long-Term Comparison With Meniscal Allograft Transplantation Is Pending.

Because of the prevalence of meniscal injuries and the difficulty treating irreparable tears and large defects, there has been increasing research and resultant engineering strategies over the past 20 years that have resulted in development of various meniscal scaffolds and meniscal implants. At this time, meniscal allograft transplant may be the "standard" consideration for the nonarthritis, meniscal deficient, stable, and properly aligned painful knee, but challenges include availability, preoperative planning and sizing, costs, and logistics. Newer tissue-engineered implants can minimize these concerns, and recent systematic review shows these may provide short-term improvement in knee pain and function. However, studies demonstrating long-term improvements remain pending, and it is unclear whether these implants will result in outcomes better than meniscal allograft transplant.

Editorial Commentary: Revision Meniscal Allograft Transplantation is a Bridge Option for Appropriately Indicated Patients With Realistic Patient Expectations in the Hands of Experienced Knee Surgeons Able to Perform All Necessary Concomitant Procedures.

Primary meniscal allograft transplantation (PMAT) is an effective yet sometimes short-term solution to postmeniscectomy syndrome. Survivorship beyond 10 years can carry a guarded prognosis. Alternatives after failure of PMAT are typically total or unicompartmental arthroplasty, which, depending on desired activity level, can be reasonable options for older patients. However, when faced with younger, otherwise healthy patients, revision meniscal allograft transplantation (RMAT) shows outcomes in appropriately indicated patients when concomitant pathology is also addressed. Patient expectations must be tempered (i.e., they should not expect to achieve an International Knee Documentation Committee score of 70 to 100, but rather 40 to 70 meaning that a patient can function reasonably well in activities of daily living). Thus RMAT is a viable "salvage" or "bridge" option in the hands of experienced high-volume knee surgeons (to ensure meticulous surgical technique and the ability to perform all necessary concomitant procedures). Patients must have appropriate expectations and be appropriately indicated.

Clinical Outcomes After Polyurethane Meniscal Scaffolds Implantation Remain Stable Despite a Joint Space Narrowing at 10-Year Follow-Up.

PURPOSE: To report the clinical outcomes, radiologic evolution, and survivorship of a series of patients affected by the postmeniscectomy syndrome and treated with a polyurethane scaffold at a minimum 10-year follow-up. In addition, the radiologic evolution of these patients was also assessed. METHODS: All the patients operated on with a polyurethane meniscal scaffold implantation to treat postmeniscectomy syndrome from 2008 to 2011 were prospectively followed. Clinical evaluations and radiologic studies were assessed at the preoperative period, at 5-year follow-up, and at minimum 10-year follow-up. Clinical outcomes were based on patient-reported outcomes (e.g., the Knee injury and Osteoarthritis Outcome Score, International Knee Documentation Committee, Lysholm, and Tegner). Radiographical evaluation of the joint-space narrowing was done in the Rosenberg view. Failure was defined as patients who required surgery to remove the scaffold or those patients who needed surgery for a total or partial knee replacement. RESULTS: Twenty-one of 27 patients, with a mean age of 56 ± 9.8 years, were available for the final follow-up. The mean follow-up was 11.8 (range, 10-12.7) years. Six patients were lost to follow-up. All functional scores showed a significant improvement (P < .001) at the 5- and 10-year follow-up. The exception was the Tegner score, which remained stable. The joint-space width was maintained from the preoperative period (1.9 ± 1.2 mm) up to the 5-year follow-up (1.3 ± 1.5 mm, P = .3) and decreased by the last evaluation (0.6 ± 1.2 mm, P = .001) at the last follow-up. Two (9.5%) of 21 patients were converted to a total knee replacement during the study period. None of the other patients needed revision surgery during the study period. CONCLUSIONS: The polyurethane meniscal scaffold provides significant and stable pain relief over time and improved functional outcomes at a minimum of 10 years after surgery. However, degenerative changes progressed in the treated compartment, with a joint-space narrowing over the 10-year period. LEVEL OF EVIDENCE: Level IV, retrospective case series.

Revision and Primary Meniscal Allograft Transplantations Provide Clinical Benefit at Mid-Term Follow-Up: A Matched-Cohort Analysis of Patient-Reported Outcomes, Reoperations, and Failures.

PURPOSE: To report the mid-term outcomes of patients who underwent revision meniscal allograft transplantation (RMAT) and compare survivorship free from reoperation and failure with a matched cohort of patients who underwent primary meniscal allograft transplantation (PMAT). METHODS: A retrospective review of prospectively collected data identified patients who underwent RMAT and PMAT between 1999 and 2017. A cohort of PMAT patients matched at a ratio of 2:1 with respect to age, body mass index, sex, and concomitant procedures served as the control group. Patient-reported outcome measures (PROMs) at baseline and at a minimum of 5 years postoperatively were collected. PROMs and the achievement of clinically significant outcomes were analyzed within groups. Graft survivorship free from meniscal reoperation and failure (arthroplasty or subsequent RMAT) was compared between cohorts using log-rank testing. RESULTS: During the study period, 22 RMATs were performed in 22 patients. Of these RMAT patients, 16 met the inclusion criteria (73% follow-up rate). The mean age of RMAT patients was 29.7 ± 9.3 years, and the mean follow-up period was 9.9 ± 4.2 years (range, 5.4-16.8 years). There were no differences between the RMAT cohort and the 32 matched PMAT patients with respect to age (P = .292), body mass index (P = .623), sex (P = .537), concomitant procedures (P ≥ .286), or baseline PROMs (P ≥ .066). The patient acceptable symptomatic state was achieved by the RMAT cohort for the subjective International Knee Documentation Committee score (70%), Lysholm score (38%), and Knee Injury and Osteoarthritis Outcome Score subscales (Pain [73%], Symptoms [64%], Sport [45%], Activities of Daily Living [55%], and Quality of Life [36%]). In the RMAT cohort, 5 patients (31%) underwent subsequent reoperation at a mean of 4.7 ± 2.1 years (range, 1.7-6.7 years) and 5 patients met the criteria for failure at a mean of 4.9 ± 2.9 years (range, 1.2-8.4 years). There were no significant differences in survivorship free from reoperation (P = .735) or failure (P = .170) between the RMAT and PMAT cohorts. CONCLUSIONS: At mid-term follow-up, most patients who underwent RMAT achieved the patient acceptable symptomatic state for the subjective International Knee Documentation Committee score and the Knee Injury and Osteoarthritis Outcome Score subscales of Pain, Symptoms, and Activities of Daily Living. Additionally, there were no differences in survival free from meniscal reoperation or failure between the PMAT and RMAT cohorts. LEVEL OF EVIDENCE: Level III, retrospective comparative cohort.

Single-incision bone bridge lateral meniscus allograft transplantation: preserving neurovascular safety with promising results for posterior horn distortion and graft maturation.

PURPOSE: This study aimed to investigate the graft maturation and safety of single-incision bone bridge lateral meniscus allograft transplantation (LMAT). METHODS: This study involved 35 patients who underwent LMAT between 2019 and 2020. All patients completed at least 2 years of follow-up (median 34 months; range 24-43) and underwent preoperative magnetic resonance imaging (MRI) to assess the trajectory safety of the leading suture passer and all-inside suture instrument (Fast-Fix). Graft status was evaluated according to the Stoller classification. RESULTS: Based on preoperative MRI measurements, the expected trajectory of the leading suture passer did not transect the common peroneal nerve (CPN), with the closest distance between the expected trajectory and CPN being 1.4 mm and the average distance being 6.8 ± 3.2 mm. The average distance from the lateral meniscal posterior horn (LMPH) to the popliteal neurovascular bundle (PNVB) was 7.4 ± 2.6 mm and the nearest was 4.8 mm. The expected trajectory of the all-inside suturing instrument did not transect the PNVB when the distance was at least 12 mm, from the most lateral margin of the posterior cruciate ligament (PCL). Grade 3 signal intensity in the posterior third of the allograft on MRI was observed in 6 of 35 (17.1%) patients. Amongst the grade 3 signal intensities in the posterior one-third of the allografts, 3 of the 35 (8.5%) LMATs had a distorted contour. CONCLUSION: The single-incision bone bridge LMAT technique introduced in this study is a convenient approach that preserves neurovascular safety and provides good results for the distortion of the posterior horn of the allograft and graft maturation. The safety zone for the penetrating devices during the procedure extended from 12 mm laterally to the most lateral margin of the PCL to the medial margin of the popliteal hiatus. LEVEL OF EVIDENCE: IV.

Early Graft Tear As a Major Risk Factor for the Clinical Failure of Lateral Meniscal Allograft Transplantation.

BACKGROUND: Graft tears are often observed on magnetic resonance imaging after lateral meniscal allograft transplantation (MAT). Their characteristics, such as the location and configuration, are likely to be different depending on the timing of the injury. However, the clinical relevance of early and late graft tears has not been investigated. HYPOTHESIS: (1) Both early and late graft tears would be associated with the clinical failure of lateral MAT, and (2) an early graft tear (ET) would lead to worse outcomes than a late graft tear (LT) or an intact graft. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 261 patients who had undergone lateral MAT between March 2000 and June 2019 were retrospectively reviewed. The graft tear was investigated using magnetic resonance imaging, which was performed routinely during the first postoperative year and every 2 years thereafter. The patients were classified according to the timing of the graft tear: no graft tear (NT) group, ET (≤1 year after surgery) group, and LT (>1 year after surgery) group. Clinical failure was defined as (1) reoperations including arthroplasty, realignment osteotomy, revision MAT, and meniscectomy (>50% of the graft or to the zone of the meniscocapsular junction) or (2) a Lysholm score of <65. Risk factors for a low survival rate were investigated using Cox regression analysis. A comparison of the Lysholm scores for each group was also performed. RESULTS: There were 24 (9.2%) patients who had clinical failure at a mean follow-up of 7.5 ± 4.3 years. The overall survival rate at 5 years was 92.8% (95% CI, 91.1%-94.5%). A graft tear was noted in 80 patients: 23 patients in the ET group and 57 patients in the LT group. The most common tear pattern was a meniscocapsular tear in the ET group and a complex tear in the LT group. The hazard ratios for clinical failure in the ET and LT groups were 30.7 (95% CI, 9.4-76.4; P < .001) and 4.0 (95% CI, 1.3-12.9; P = .013), respectively. The Lysholm score of the ET group (82.7 ± 14.8) was significantly lower than that of the other 2 groups (NT: 87.6 ± 11.7; LT: 90.7 ± 9.0; P = .024). CONCLUSION: An ET was a major risk factor for the clinical failure of lateral MAT. An LT was associated with a lower survival rate. An ET was also associated with worse clinical outcomes.

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.

Survivorship After Lateral Meniscal Allograft Transplantation Plus Concurrent Cartilage Procedure in Patients With Poor Cartilage Status: A Comparative Study.

BACKGROUND: The effect of a concurrent cartilage procedure in lateral meniscal allograft transplantation (MAT) in patients with bipolar cartilage lesions (high-grade lesions on both the femoral and the tibial side) is not well studied. An objective evaluation of graft status after MAT and a concurrent cartilage procedure has not been reported. PURPOSE: To investigate the effect of concurrent cartilage procedures and lateral MAT on objective and clinical outcomes, including survival, in patients with bipolar cartilage lesions. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 149 patients with high-grade (International Cartilage Regeneration & Joint Preservation Society grade 3 or 4) cartilage lesions were enrolled and assigned to 1 of 3 groups based on the cartilage procedure and cartilage status at the time of MAT. Femoral cartilage procedures (microfracture, n = 18; osteochondral autograft transfer, n = 13) and lateral MAT were performed in 31 patients with bipolar cartilage lesions (cartilage procedure group). Another 70 patients with bipolar lesions underwent only lateral MAT without cartilage procedure (bipolar lesion group). The remaining 48 patients, who had high-grade lesions only on the tibial side and underwent lateral MAT without a cartilage procedure, were selected as a control group (unipolar lesion group). Anatomic survival was objectively assessed by follow-up magnetic resonance imaging and second-look arthroscopy. Clinical survivorship was determined with a Lysholm score <65 or need for additional surgery, such as revision MAT. RESULTS: The mean Lysholm score improved from 67.2 ± 15.9 preoperatively to 86.7 ± 11.1 with a mean follow-up of 78.0 ± 51.2 months (P < .001). The postoperative scores were not significantly different between the 3 groups. The estimated 5-year anatomic survival rate in the cartilage procedure group (86.7%) was higher than that in the bipolar lesion group (65.0%; P = .043) but comparable with that in the unipolar lesion group (90.2%; P = .572). The estimated 5-year clinical survival rates were not significantly different between the groups (P = .187). CONCLUSION: A concurrent femoral cartilage procedure improved the anatomic survival rate in patients with bipolar chondral lesions who underwent lateral MAT. This finding suggests that the cartilage procedure is an effective treatment choice and may improve the status of an allograft after lateral MAT for patients with bipolar cartilage lesions.

Bone bridge technique for lateral meniscal allograft transplantation: no difference in clinical outcome compared to the soft tissue technique.

PURPOSE: There is considerable debate regarding the optimal method of fixation for lateral meniscus allograft transplantation (MAT), with bone bridge techniques technically harder but allowing maintenance of root attachments, while soft tissue techniques are potentially more challenging for healing. The aim of this study was to compare the clinical results of the bone bridge and soft tissue techniques for lateral MAT in terms of failure, re-operation rate, complications and patient reported outcomes. METHODS: Retrospective analysis of prospectively collected data for patients undergoing primary lateral MAT with a minimum of 12-month follow-up. Patients following surgery utilising the bone bridge technique (BB) were compared with historical control patients who underwent MAT with the soft tissue technique (ST). Outcome was assessed by failure rate, defined as removal or revision of the meniscus transplant, survivorship by Kaplan-Meir analysis, re-operation rates, and other adverse event. Patient-reported outcome measures (PROMs) were compared using data at the 2-year point or 1 year if not reached 2 years. RESULTS: One-hundred and twelve patients following lateral meniscal transplants were included, 31 in the BB group and 81 in the ST historical control group, with no differences in demographics between both groups. Median follow-up for the BB group was 18 (12-43) months compared to 46 (15-62) months for the ST group. There were 3 failures (9.6%) in the BB group v 2 (2.4%) in the ST group (n.s.) with a mean time to failure of 9 months in both groups. 9 patients (29%) required a re-operation (all cause) in the BB group v 24 patients (29.6%) in the ST group (n.s). There was no difference in complications between both groups. There was significant improvement (p < 0.0001) in all PROMs (Tegner, IKDC, KOOS and Lysholm) between baseline and 2-year follow-up for both groups but no between-group differences. CONCLUSION: Lateral MAT has a high success rate for symptomatic meniscal deficiency with significant benefits irrespective of the fixation technique. There is no advantage in performing the more technically demanding BB technique over ST fixation. LEVEL OF EVIDENCE: Level 2.

Graft Extrusion of 3 Millimeters Is Acceptable at a Minimum of 5-Year Outcomes for Lateral Meniscal Allograft Transplantation.

PURPOSE: To determine the acceptable amount of graft extrusion based on long-term radiographic outcomes in lateral meniscal allograft transplantation (MAT). METHODS: 94 lateral MAT patients with a minimum 5-year follow-up period were reviewed. Graft extrusion was measured on MRI scans taken 1 year after surgery, and the study population was divided according to the amount of extrusion: group A, extrusion <3 mm; group B, 3 mm ≤ extrusion <5 mm; and group C, extrusion ≥5 mm. For radiographic evaluation, the bilateral lateral joint space widths (JSWs) were measured on a standing 45° flexion posteroanterior radiograph. To standardize the measurements, the affected JSW was divided by the contralateral JSW. The change in the standardized JSW (ΔJSWstd) between the preoperative and latest follow-up assessments was analyzed according to the three groups. Multiple regression analysis was performed to control other related factors, such as lower limb alignment and cartilage status at the time of MAT. The acceptable amount of graft extrusion was calculated using a receiver operating characteristic (ROC) curve for the third quartile of ΔJSWstd. Clinical outcomes were evaluated using the Lysholm score and were compared among the groups. RESULTS: The mean follow-up duration was 8.3 ± 3.1 years. There were 54, 25, and 15 patients in group A, group B, and group C, respectively. In multiple regression analysis, both group B and group C had significant associations with ΔJSWstd and their beta coefficients were comparable (group B, P < .001, ß = .642; group C, P < .001, ß = 0.613). No significant difference in ΔJSWstd was found between group B and group C (P = .494). On the basis of the ROC curve, the acceptable amount of graft extrusion was 3.74 mm (sensitivity, 81.8%; specificity, 77.8%). There were no differences in the Lysholm scores among the three groups (P = .329). CONCLUSIONS: ΔJSWstd differed between graft extrusion <3 mm (group A) and graft extrusion ≥3 mm (group B and group C). However, there was no significant difference in ΔJSWstd between group B and group C. No significant difference in clinical outcomes was found according to graft extrusion. This study gave supporting evidence for the currently recognized acceptable amount of graft extrusion (3 mm). LEVEL OF EVIDENCE: Level III, retrospective cohort study.

Initial Outcomes After Unicompartmental Tibiofemoral Bipolar Osteochondral and Meniscal Allograft Transplantation in the Knee Using MOPS-Preserved Fresh (Viable) Tissues.

BACKGROUND: Unicompartmental tibiofemoral bipolar osteochondral allograft transplantation (OCAT) with meniscal allograft transplantation (MAT) has not historically been associated with consistently successful outcomes for treatment of knee articular cartilage defects with meniscal deficiency. HYPOTHESIS: Primary OCAT and MAT using fresh tissues will be associated with successful short-term outcomes based on statistically significant and clinically meaningful improvements in pain and function in the majority of patients. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Patients were prospectively enrolled into a registry for outcomes after OCAT and MAT. Patients included those who underwent primary OCAT and MAT using Missouri Osteochondral Preservation System (MOPS)-preserved allografts for treatment of large bipolar tibiofemoral articular cartilage defects with meniscal deficiency and had a minimum of 2-year follow-up data. RESULTS: A total of 76 patients (n = 52 male; 68%) met inclusion criteria (mean follow-up, 52 months). The mean age was 41.1 years (range, 15-69 years), and the mean body mass index was 28.9 (range, 17-46); 48 patients underwent another OCAT in addition to the unicompartmental bipolar tibiofemoral OCAT and MAT; 23 patients (30.3%) were documented to be nonadherent to the prescribed postoperative restriction and rehabilitation protocol. The initial success rate (>2 years) was 77.6%, with 8 patients (10.5%) undergoing revision and 9 (11.8%) converting to arthroplasty. Variables associated with an increased risk for treatment failure (revision or arthroplasty) included ipsilateral osteotomy (P = .046; odds ratio [OR] = 3.3), ipsilateral concurrent procedure (P = .0057; OR = 5.5), and nonadherence (P = .0009; OR = 7.2). None of the patients undergoing revision surgery required arthroplasty at the time of data analysis such that the overall success rate for primary and revision unicompartmental bipolar OCA plus MAT was 88.2%. There were statistically significant (P < .0001) and clinically important improvements for all patient-reported outcomes at each annual follow-up time point. CONCLUSION: Unicompartmental tibiofemoral bipolar OCAT and MAT can result in successful short-term outcomes (2-6 years) and satisfaction in the majority of patients (78%). Primary MOPS-preserved OCAT with MAT for treatment of femoral condyle and tibial plateau articular cartilage defects with concurrent meniscal deficiency was associated with statistically significant and clinically meaningful improvements in patient-reported measures of pain and function.

Systematic Review of Clinical Results After Medial Meniscus Allograft Transplantation Reveals Improved Patient Reported Outcomes at Greater Than 5 Years Follow-Up.

PURPOSE: To systematically summarize the medial meniscus allograft transplantation (MAT) reported outcomes and evaluate whether the surgical technique is associated with allograft extrusion and knee function. METHODS: Systematic review was conducted according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Inclusion criteria were English-language clinical studies involving arthroscopically assisted medial MAT that reported the surgical technique and the presence of graft extrusion or functional outcomes after surgery. Studies in which outcomes for medial MAT could not be separated from lateral MAT were excluded. Surgical technique, allograft-related characteristics, and clinical outcomes were extracted. RESULTS: Twenty-four studies with 328 medial MAT were included, 58.3% studies qualified as level 4 of evidence, 29.2% as level 3, and 12.5% as level 2. Allograft fixation techniques were bone plug (235/328 [71.6%]), bone bridge/trough (55/328 [16.8%]), and soft-tissue suture fixation only (38/328 [11.6%]). Relative percentage of extrusion after surgery ranged from 24.8% to 53.7%. Major extrusion (>3 mm) ranged from zero to 78%. Overall, functional scores improved after medial MAT. None of surgical techniques were associated with poor functional outcomes or extruded meniscus; however, nonanatomical placement of the anterior and posterior horns appeared to increase meniscus extrusion. CONCLUSION: Medial MAT provides favorable outcomes, with acceptable rates of complication and failure regardless of surgical technique. Although allograft extrusion appears equivalent for both bone plug and soft-tissue fixation techniques, positioning allograft horns at the native meniscal footprint may be critical for preventing extrusion. However, the heterogeneity and low level of evidence of the studies included in this review prevent decisive conclusions regarding optimal MAT fixation techniques, clinical significance of allograft extrusion, or comparative clinical outcomes after medial MAT. LEVEL OF EVIDENCE: Level IV - systematic review of Level II to IV studies.