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Editorial Commentary: Knee Meniscal Allograft Transplantation Results in Significantly Improved Outcomes in the Majority Patients, but There Is Wide Variability in the Rate at Which Athletes Return to Sports

      Abstract

      Meniscal allograft transplantation (MAT) is the reconstructive procedure of choice following a total or near-total meniscectomy for the symptomatic patient with a stable, well-aligned knee prior to the onset of degenerative arthritis. Historically, the goals were to eliminate symptoms with activities of daily living and improve longevity of the articular cartilage. However, athletically active individuals are rarely satisfied unless they return to their prior level of function, which is dependent on patient-specific, knee-specific, and sports-specific factors. Despite the fact that subjective patient-reported outcomes are significantly improved in the majority of MAT patients, there is wide variability in the rate at which athletic patients are able to return to sports, when they return, and their ultimate level of performance. We advise active individuals who undergo a MAT to pursue “low-impact” activities based on 10-year survivorship of 70% to 80%. Risk of a recurrent meniscal tear is the most common complication, and the ability of MAT to prevent osteoarthritis is unproven.
      Meniscal tears are one of the most common injuries seen in athletic patients and often require surgery to address the joint line pain, catching, and swelling that impair both athletic activity and normal knee function. The majority of meniscal tears are simply debrided, since only 20% of these tears can be repaired because of on the limited synovial-based blood supply and tear patterns amenable to repair.
      • Yoon K.H.
      • Park K.H.
      Meniscal repair.
      The importance of meniscal preservation is supported by abundant biomechanical data attesting to the role the menisci play in load distribution, shock absorption, knee stability, proprioception, and synovial fluid dispersal.
      • Kim J.G.
      • Lee Y.S.
      • Bae T.S.
      • et al.
      Tibiofemoral contact mechanics following posterior root of medial meniscus tear, repair, meniscectomy, and allograft transplantation.
      Patients who have undergone a complete or near-complete meniscectomy and subsequently develop disabling pain and evidence of impending articular cartilage degeneration in the same compartment may be candidates for meniscal allograft transplantation (MAT).
      • Rao A.J.
      • Erickson B.J.
      • Cvetanovich G.L.
      • Yanke A.B.
      • Bach Jr., B.R.
      • Cole B.J.
      The meniscus-deficient knee: Biomechanics, evaluation, and treatment options.
      Ligamentous stability, neutral alignment, and minimal preexisting arthritis or chondral defects are prerequisites for success and should be addressed either prior to, or concurrent with, the transplantation.
      • Getgood A.
      • Laprade R.F.
      • Verdonk P.
      • et al.
      International Meniscus Reconstruction Experts Forum (IMREF) 2015 Consensus Statement on the practice of meniscal allograft transplantation.
      Clinical case series and systematic reviews support favorable clinical outcomes in terms of symptom relief with activities of daily living (ADLs) at short- and mid-term follow-up, while long-term prevention of osteoarthritis remains debatable.
      • Rosso F.
      • Bisicchia S.
      • Bonasia D.E.
      • Amendola A.
      Meniscal allograft transplantation: A systematic review.
      • Elattar M.
      • Dhollander A.
      • Verdonk R.
      • Almqvist K.F.
      • Verdonk P.
      Twenty-six years of meniscal allograft transplantation: Is it still experimental? A meta-analysis of 44 trials.
      • Figueroa F.
      • Figueroa D.
      • Calvo R.
      • Vaisman A.
      • Espregueira-Mendes J.
      Meniscus allograft transplantation: Indications, techniques and outcomes.

      Bonanzinga T, Grassi A, Altomare D, Vitale ND, Zaffagnini S, Marcacci M. Long sports career and satisfactory clinical outcomes after meniscal allograft transplantation (MAT) in young professional athletes involved in strenuous sports [published online November 23, 2021]. Knee Surg Sports Traumatol Arthrosc https://doi.org/10.1007/s00167-021-06779-2.

      • Ahmed A.
      • Rinaldi J.
      • Noorzad A.
      • Zikria B.
      Return to sports following meniscal allograft transplantation is possible but remains questionable: a systematic review.
      • Baldairon F.
      • Toanen C.
      • Pujol N.
      Functional and anatomical outcomes of single-stage arthroscopic bimeniscal replacement.
      • Saltzman B.M.
      • Meyer M.A.
      • Weber A.E.
      • Poland S.G.
      • Yanke A.B.
      • Cole B.J.
      Prospective clinical and radiographic outcomes after concomitant anterior cruciate ligament reconstruction and meniscal allograft transplantation at a mean 5-year follow-up. The.
      However, regarding return to sports following MAT, unlike death and taxes, there are no guarantees.
      Despite the basic science and clinical evidence that MAT provides symptomatic improvement in normal physical activities, there is considerable uncertainty regarding the ability of athletic patients to return to more strenuous activities involving running, jumping, cutting, and pivoting, as well as whether or not these activities are even recommended. Furthermore, there is even less information available to guide both clinicians and patients in terms of the optimal time postoperatively to resume athletic activity, the recommended maximum level of athletic intensity, the likelihood of resuming at the pre-injury level of play, and the impact of sports on the natural history of the knee following MAT. Potential differences between medial and lateral meniscal allografts, the effect of concurrent ligamentous and/or chondral procedures and patient age are factors that complicate this issue even further. Recent retrospective case series have attempted to address return to sports following a MAT.
      • Cvetanovich G.L.
      • Christian D.R.
      • Garcia G.H.
      • et al.
      Return to sport and patient satisfaction after meniscal allograft transplantation.
      • Puzzitiello R.N.
      • Liu J.N.
      • Garcia G.H.
      • et al.
      Return to sport and outcomes after concomitant lateral meniscal allograft transplant and distal femoral varus osteotomy.
      • Searle H.
      • Asopa V.
      • Coleman S.
      • McDermott I.
      The results of meniscal allograft transplantation surgery: What is success?.
      • Liu J.N.
      • Agarwalla A.
      • Garcia G.H.
      • et al.
      Return to sport and work after high tibial osteotomy with concomitant medial meniscal allograft transplant.
      • Baldairon F.
      • Toanen C.
      • Pujol N.
      Functional and anatomical outcomes of single-stage arthroscopic bimeniscal replacement.
      Unfortunately, there is often wide variability in return-to-sports rates between individual studies and prior systematic reviews, which were published earlier than these more recent studies.
      • Grassi A.
      • Bailey J.R.
      • Filardo G.
      • Samuelsson K.
      • Zaffagnini S.
      • Amendola A.
      Return to sport activity after meniscal allograft transplantation: At what level and at what cost? A systematic review and meta-analysis.
      ,
      • Lee B.S.
      • Kim H.J.
      • Lee C.R.
      • et al.
      Clinical outcomes of meniscal allograft transplantation with or without other procedures: A systematic review and meta-analysis.
      To address this uncertainty regarding the return to sports in this subset of patients, Ahmed, Rinaldi, Noorzad and Zikria have systematically reviewed the available literature to determine the feasibility of athletic activity following MAT in their study entitled, “Return to Sports Following Meniscal Allograft Transplantation Is Possible but Remains Questionable: A Systematic Review”.

      United States, Congress, National Heart, Lung and Blood Institute. Study Quality Assessment Tools, National Institutes of Health, 1 July 2021. https://www.nhlbi.nih.gov/health-topics/study-quality-assessment-tools. Accessed January 4, 2022.

      Their systematic search of the literature published through 2020 resulted in 14 eligible studies that assessed 670 patients. Consistent with the wide variance in mean patient age (range: 12.6 to 45.3 years) and follow-up (range: 2.0 to 9.3 years), these authors found that the return-to-play rate following a MAT varied between 20% and 91.7% with the mean time to return ranging from 7.6 months to 16.9 months, postoperatively. Despite this variability in return to sports, there was consistent improvement in patient-reported outcomes across all studies. This improvement was noted despite the variability in patient age, number of concomitant procedures, which meniscus was transplanted, graft fixation technique, and outcome measures used. Given the significant variation that existed among the included studies, outcome data could only be reported in ranges precluding any quantitative or pooled analyses required of a meta-analysis. The authors conclude that the current level of evidence regarding the clinical outcome following MAT is of low quality, since all of the studies included in their systematic review were level IV case series. Despite these limitations, Ahmed et al. should be congratulated on addressing an important topic for many active patients who undergo MAT yet want to continue participation in some degree of athletic activity.
      The authors qualitatively evaluated each study with the use of the National Institutes of Health assessment tool of pre-post uncontrolled studies, which consists of 12 questions examining a study’s objective, sample size, treatment(s), outcome measures, and statistical analysis.

      United States, Congress, National Heart, Lung and Blood Institute. Study Quality Assessment Tools, National Institutes of Health, 1 July 2021. https://www.nhlbi.nih.gov/health-topics/study-quality-assessment-tools. Accessed January 4, 2022.

      In summary, only four studies had good overall rating, four had a moderate rating, and six had a poor rating. There were a multitude of deficiencies among the 14 studies, such as unclear eligibility criteria, >20% loss to follow-up, absence of a defined statistical plan, and an unclear surgical technique that resulted in a low level of evidence for this body of research.
      A deeper analysis of the overall return to sports rate and time to return to sports revealed that despite the wide range in both metrics noted earlier, 12 of the 14 studies reported a higher mean return to sports rate ranging from 73.5% to 91.7%. Similarly, seven of the nine studies that provided the time to return to sports, reported a time between 8.6 and 12.6 months following surgery. Similarly, total reoperation rates varied between 3.1% and 80%, and mean total failure rates (both clinical and surgical) ranged from 1.1% to 30.1%. Therefore, it is difficult to summarize the limited literature that is available since studies that are “outliers” in various outcome measures may skew the data either in favor of or against a return to sports following a MAT.
      Although the percentage of patients in the study by Ahmed et al.,

      United States, Congress, National Heart, Lung and Blood Institute. Study Quality Assessment Tools, National Institutes of Health, 1 July 2021. https://www.nhlbi.nih.gov/health-topics/study-quality-assessment-tools. Accessed January 4, 2022.

      who were able to return to sports following a MAT was relatively high, the ability to return to the same level of preinjury participation was not as certain. For example, in the study by Noyes et al.
      • Noyes F.R.
      • Barber-Westin S.D.
      • Rankin M.
      Meniscal transplantation in symptomatic 513 patients less than fifty years old.
      86% of patients returned to a higher level of play. Whereas Searle et al.
      • Searle H.
      • Asopa V.
      • Coleman S.
      • McDermott I.
      The results of meniscal allograft transplantation surgery: What is success?.
      reported that the majority (74.4%) of their patients returned to a lower level of play. This would suggest that the ability to resume sports at the same level of play is just as variable as the ability to return at all. Many factors may contribute to this finding that are related both to the patient’s knee, as well as the type of sport and level of competition he or she attempts to resume.
      Despite the limitations in the literature, the systematic review by Ahmed et al.
      • Ahmed A.
      • Rinaldi J.
      • Noorzad A.
      • Zikria B.
      Return to sports following meniscal allograft transplantation is possible but remains questionable: a systematic review.
      makes a substantial contribution to the literature by focusing specifically on the ability to return to sports following a MAT. The current evidence suggests that the return-to-sport rate is reasonably high (though not uniformly so) with commensurate improvement in patient-reported outcome measures.

      Bonanzinga T, Grassi A, Altomare D, Vitale ND, Zaffagnini S, Marcacci M. Long sports career and satisfactory clinical outcomes after meniscal allograft transplantation (MAT) in young professional athletes involved in strenuous sports [published online November 23, 2021]. Knee Surg Sports Traumatol Arthrosc https://doi.org/10.1007/s00167-021-06779-2.

      ,
      • Cvetanovich G.L.
      • Christian D.R.
      • Garcia G.H.
      • et al.
      Return to sport and patient satisfaction after meniscal allograft transplantation.
      ,
      • Puzzitiello R.N.
      • Liu J.N.
      • Garcia G.H.
      • et al.
      Return to sport and outcomes after concomitant lateral meniscal allograft transplant and distal femoral varus osteotomy.
      ,
      • Grassi A.
      • Bailey J.R.
      • Filardo G.
      • Samuelsson K.
      • Zaffagnini S.
      • Amendola A.
      Return to sport activity after meniscal allograft transplantation: At what level and at what cost? A systematic review and meta-analysis.
      These conclusions are tempered by the low level of evidence on which these results are based due, primarily, to the significant variability in patient-specific factors such as age, graft fixation technique, side of transplant, concomitant procedures, degree of pre-existing arthritis and duration of follow-up. Unfortunately, graft size mismatch between the donor and recipient meniscus—possibly the single most important predictor of failure—as well as graft extrusion are poorly, if ever, quantified in any clinical series. Sport-specific metrics, such as ability and timing of return to play, desired level of athletic competition and attainment of the preinjury level of performance only add further complexity to an already nebulous topic. The relative rarity of meniscal transplantation compounded by these patient-specific and sport-specific variables complicates the ability to perform higher-quality studies evaluating the return to sports following a MAT. Until the relative importance of these factors is better understood, we should remain cautious before suggesting to patients that a return to preinjury levels of athletic activity is not only possible but also recommended.
      Our approach regarding this issue has been to advise active individuals who undergo a MAT to pursue “low-impact” activities with the admonition that the overall 10-year success rate based on most clinical series is only 70%-80%,
      • Verdonk P.C.
      • Demurie A.
      • Almqvist K.F.
      • Veys E.M.
      • Verbruggen G.
      • Verdonk R.
      Transplantation of viable meniscal allograft. Survivorship analysis and clinical outcome of one hundred cases.
      that the risk of a recurrent meniscal tear is the most common complication following the procedure,
      • Young J.
      • Tudor F.
      • Mahmoud A.
      • Myers P.
      Meniscal transplantation: Procedures, outcomes, and rehabilitation.
      and that the ability of a MAT to prevent long-term osteoarthritis is unproven.
      • Smith N.A.
      • Parkinson B.
      • Hutchinson C.E.
      • Costa M.L.
      • Spalding T.
      Is meniscal allograft transplantation chondroprotective? A systematic review of radiological outcomes.
      ,

      Wang DY, Zhang B, Li YZ, Meng XY, Jiang D, Yu JK. The long-term chondroprotective effect of meniscal allograft transplant: A 10- to 14-year follow-up study. Am J Sports Med In press. https://doi.org/10.1177/03635465211054022.

      The majority of patients understand the risks of further knee issues in both the short and long term and willingly accept the compromise of reduced activity for a relatively symptom-free knee. Furthermore, patients should be made aware that a MAT is a “salvage procedure” to make a bad problem tolerable, not to enable strenuous jumping, cutting, and pivoting analogous to an anterior cruciate ligament reconstruction. Unfortunately, even with appropriate patient education, some previously active individuals will attempt to “push the envelope” by returning to high-impact weight-bearing exercise. While we hope they do well, we are admittedly pessimistic that a meniscal allograft will be able to withstand such activities in the majority of patients.
      Meniscal transplantation is a technically challenging operation performed relatively infrequently for a small subset of physiologically younger patients with a symptomatic meniscus-deficient knee. The interplay of knee pathology, surgical details, and athletic proclivity unique to each patient makes it very difficult to compare “apples to apples” when trying to interpret the existing literature in order to make informed decisions regarding postoperative activity. Optimally, these questions are best answered by prospective randomized trials matching patients for as many variables as possible. The systematic review by Ahmed et al.
      • Ahmed A.
      • Rinaldi J.
      • Noorzad A.
      • Zikria B.
      Return to sports following meniscal allograft transplantation is possible but remains questionable: a systematic review.
      is informative, but merely an initial step in determining the potential for athletic activity following an MTA. Future work should focus on clarifying a number of issues, such as 1) what level of athletic activity should be permissible, 2) the relationship between the degree of osteoarthritis and athletic activity, and 3) the optimal timing of return to sports based on the degree of lower extremity impact. In the meantime, these patients should be advised that a MAT will reliably improve those symptoms necessitating the surgery, but the return to more strenuous athletic activity should be undertaken with caution. Although it is possible to resume some level of sports following a MAT, the real question isn’t when athletic activity is advisable, but if it should be advised at all.

      Supplementary Data

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