Long-term Survivorship and Function of Meniscus Transplantation

Long-term Results of Meniscus Allograft Transplantation with Bone Fixation Show Improved Outcomes but Progression of Joint Space Narrowing, Osteoarthritis, and Cartilage Degeneration

PURPOSE

To investigate the clinical and objective outcomes of meniscal allograft transplantation (MAT) using bone fixation in patients after a minimum follow-up duration of 15 years, and to compare the demographic factors and allograft status between patients who experienced progression of osteoarthritis and those who did not.

METHODS

The consecutive patients who underwent primary MAT between December 1996 and January 2008 were retrospectively reviewed. The inclusion criteria was primary MAT with a minimum follow-up duration of 15 years. Clinical outcomes were evaluated using the modified Lysholm score, along with an evaluation of clinical failure. In objective outcomes, the progression of joint space narrowing, osteoarthritis, and the status of the associated cartilages and allografts were evaluated with follow-up radiographs and MRI.

RESULTS

Among the 79 cases, 54 knees in 52 patients were included in the study and evaluated for clinical outcomes. The mean Lysholm score improved from 73.9 ± 17.5 preoperatively to 86.4 ± 15.6 over a mean follow-up period of 17.5 ± 3.8 years (P<0.001). Regarding the Minimal clinically important differences (MCID), 38 cases (70.4%) showed an improvement in the Lysholm score. The cumulative clinical survival rate was 87.0%. Objective evaluations evaluated in 32 cases with a minimum of 15 years of radiographic data revealed significant progression of joint space narrowing, osteoarthritis, and cartilage degeneration at the final follow-up, with 11 (34.4%) out of 32 cases exhibiting allograft tears involving ˃50% of the allograft. Patients with osteoarthritis progression exhibited more meniscal allograft tears and extrusion on the last follow-up MRI scan than those without progression.

CONCLUSION

Notable progression in joint space narrowing, osteoarthritis, and cartilage degeneration were observed in objective assessment. The progression of osteoarthritis might be associated with allograft tears and extrusion. In clinical evaluations, favorable long-term clinical outcomes were consistently demonstrated after MAT using the bone fixation technique.

LEVEL OF EVIDENCE

Level Ⅳ, therapeutic case series.

Meniscal Allograft versus Synthetic Graft in Treatment Outcomes of Meniscus Repair: A Mini-review and Meta-analysis

Meniscal injuries are highly correlated with osteoarthritis (OA) onset and progression. Although meniscal allograft transplantation (MAT) is a therapeutic option to restore meniscal anatomy, a shortage of donor material and the donor-derived infectious risk may be concerns in clinics. This review summarizes the literature reporting meniscus repair status in preclinical models and clinical practice using allografts or synthetic grafts. The advantages and limitations of biodegradable polymer-based meniscal scaffolds, applied in preclinical studies, are discussed. Then, the long-term treatment outcomes of patients with allografts or commercial synthetic scaffolds are compared. A total of 47 studies are included in our network meta-analysis. Compared with the meniscal allografts, the commercial synthetic products significantly improved clinical treatment outcomes in terms of the Knee Injury and Osteoarthritis Outcome Score (KOOS), Visual Analog Scale (VAS) scores, and Lysholm scores. In addition, development strategies for the next generation of novel synthetic scaffolds are proposed through optimization of structural design and fabrication, and selection of cell sources, external stimuli, and active ingredients. This review may inspire researchers and surgeons to design and fabricate clinic-orientated grafts with improved treatment outcomes.

Outcome comparison of meniscal allograft transplantation (MAT) and meniscal scaffold implantation (MSI): a systematic review

BACKGROUND

Although numerous studies have reported successful clinical outcomes of meniscal allograft transplantation (MAT) or meniscal scaffold implantation (MSI), the difference between the outcome of MAT and MSI remains unclear.

PURPOSE

To compare the overall outcomes and survival rates of MAT and MSI, aiming to provide comprehensive evidence for determining the optimal treatment strategy for meniscal defects.

METHODS

A systematic review was performed via a comprehensive search of PubMed, Embase, and the Cochrane Library. Studies of MAT or MSI were included according to the inclusion and exclusion criteria. The Lysholm score was chosen as the primary outcome measure, while secondary outcomes encompassed patient-reported outcome measures (PROMs), return to sports (RTS) rates, survival rates, and complication rates. The outcomes were stratified into two groups: MAT group and MSI group, followed by statistical comparison ( P <0.05). The quality of the included studies was assessed by the Cochrane Risk of Bias 2 (RoB2) assessment tool for randomized controlled trials (RCTs) and the Coleman Methodology Score (CMS) for non-randomized controlled trials.

RESULTS

A total of 3932 patients (2859 MAT, 1073 MSI) in 83 studies (51 MAT, 32 MSI) had the overall significant improvement in all clinical scores. The group MSI had a higher Lysholm score of both preoperative ( P =0.002) and postoperative ( P <0.001) than group MAT; however, the mean improvements were similar between the two groups ( P =0.105). Additionally, MSI had higher improvements of IKDC ( P <0.001), KOOS symptom ( P =0.010), KOOS pain ( P =0.036), and KOOS ADL ( P =0.004) than MAT. Interestingly, MAT had higher preoperative ( P =0.018) and less postoperative VAS pain ( P =0.006), which was more improved in MAT ( P <0.001). Compared with MAT, MSI had a higher 10-year survival rate ( P =0.034), a similar mid-term survival rate MAT ( P =0.964), and a lower complication rate ( P <0.001).

CONCLUSION

Both MAT and MSI could have good clinical outcomes after surgery with a similar improvement in Lysholm score. MSI had a higher 10-year survival rate and fewer complications than MAT.

LEVEL OF EVIDENCE

Level IV, systematic review.

Meniscus Allograft Transplantation in Conjunction With Arthroscopic Biologic Knee Restoration Delays Arthroplasty in Patients Older Than 50 Years

PURPOSE

To evaluate the utility of meniscus allografts in combination with other procedures to delay knee arthroplasty in patients older than 50 years previously advised joint arthroplasty.

METHODS

A total of 108 meniscus allograft transplants using the arthroscopic 3-tunnel technique between 1997 and 2019 in patients older than 50 years were retrospectively reviewed with a 2-year minimum follow-up period. Inclusion criteria were patients recommended for knee arthroplasty with pain and preservation of some joint space by standing flexion radiographs. Exclusion criteria were lack of joint space, failure to comply with rehabilitation protocol, and failure to complete research questionnaires. International Knee Documentation Committee composite and isolated pain scale were evaluated longitudinally. Time from meniscus allograft transplant to arthroplasty was measured, with failure defined as allograft excision or revision, progression to arthroplasty, or same or increased pain.

RESULTS

Eighty-six of 108 (79.6%) patients met eligibility criteria. Over the follow-up mean 8.55 (range 0.68 to 25.2) years, 42 of 87 (48.2%) grafts progressed to arthroplasty with mean time of 8.64 (median 8.05) years. Concomitant procedures did not have significant impact on survival; however, survival medians were higher among paste graft and chondroplasty and lower among osteotomy groups. At the time of reporting, 41 of 84 (48.8%) patients had intact meniscus transplants, demonstrating significant improvements (P < .001) in pain and function as assessed by International Knee Documentation Committee Score. These improvements were sustained 10 years postoperatively, correlated to a mean of 65.8 years of age. At least 50% of patients achieved Minimal Clinically Important Difference through 10 years postoperatively.

CONCLUSIONS

Meniscus allografts in combination with other arthroscopic interventions delay knee arthroplasty and improve knee symptoms of pain and function in a population of knee arthroplasty candidates older than 50 years. Influences of concomitant procedures cannot be defined.

LEVEL OF EVIDENCE

Level IV, therapeutic case series, retrospective.

Concomitant Treatment of High-Grade Cartilage Lesions Mitigates Risk of Meniscal Allograft Transplant Failure

PURPOSE

To identify frequently studied significant preoperative risk factors for meniscal allograft transplantation (MAT) failure.

METHODS

Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines were used to conduct this systematic review. The database analysis was performed in May 2022 and included PubMed, Embrace, and Cochrane. Studies between January 1, 2000, and January 1, 2021, were reviewed with search terms, including "meniscal," "meniscus," "transplantation," "transplant," and "allograft." Twenty-one full-text manuscripts met inclusion criteria of studies assessing preoperative risk factors for MAT failure defined as either clinical failure (Lysholm <65) or surgical failure (revision, removal, or conversion to knee arthroplasty).

RESULTS

In total, 21 studies were included, comprising 47.6% with Level of Evidence III and 52.4% with Level of Evidence IV. The analysis involved 2,533 patients, and the mean final follow-up ranged from 2.2 to 20.0 years. The presence of high-grade cartilage defects was the only factor found predictive of MAT surgical failure in the majority of studies in which it was analyzed (5/7 studies, 71.4%). Four of the 5 studies that found high-grade cartilage defects to be a predictor of MAT surgical failure did not treat all cartilage lesions, whereas the 2 studies that found high-grade cartilage defects an insignificant predictor of MAT surgical failure treated all defects at the time of MAT. For clinical failure, no risk factors were predictive of MAT failure in the majority of studies, although smoking and concomitant ligamentous or realignment procedures were significant in 1 study.

CONCLUSIONS

The presence of untreated high-grade cartilage appears to elevate the risk of surgical MAT failure; however, concomitant treatment of defects may mitigate their detrimental effect. There is no clear risk factor that consistently predicts clinical failure. Age, sex, body mass index, knee compartment, time from prior meniscectomy, femorotibial alignment (after correction), concomitant cartilage procedure, and laterality do not routinely influence MAT failure.

LEVEL OF EVIDENCE

Level IV, systematic review of Level III and IV studies.

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.

A Case Report of a National Judo Champion: Is Return to High-Level Contact Sports Possible After Meniscus Allograft Transplantation?

Meniscus allograft transplantation (MAT) is a surgical procedure reserved for (relatively) younger individuals who remain symptomatic after the resection of a voluminous part of the meniscus. Return to sports and certainly the level of sport post-MAT are highly variable. We present a unique case of a national judo champion who was able to compete at the highest level following MAT. Considerations regarding the rehabilitation and follow-up of this patient are provided, and the risk of rerupture is discussed. Although returning to high-level contact sports post-MAT is possible, the risk of rerupture should be considered.

Cellular Enhancement of Frozen Meniscus Allograft Combining Native Meniscus and Mesenchymal Stromal Cell Injections

OBJECTIVE

This proof-of-concept study investigated an improved cell-based injection therapy combining mesenchymal stem cells (MSCs) and meniscus cells (MCs) to support superior meniscus allograft repopulation and early revival compared to injecting MSCs alone.

DESIGN

In this controlled laboratory study, frozen meniscus allograft samples were injected vertically with a cell suspension containing different ratios of MSCs and MCs or control (lactated ringers) and cultured for 28 days. Samples were analyzed weekly for cell viability, migration, and metabolism using histological and biochemical assays. Tissue medium was analyzed for matrix metalloproteinase (MMP) expression using zymography.

RESULTS

Cellular repopulation of frozen allografts injected with different cell suspensions was validated by immunohistochemistry. Significant higher DNA content was evidenced in grafts treated with suspensions of MCs or MC:MSC (1:4 ratio). Cell metabolic activity was significantly different between all treated groups and control group after 1 week. Allografts injected with MCs showed significantly more cell proliferation than injections with MSCs. MMP2 activity was detected in medium of all grafts cellularized with MCs with or without MSCs. Scanning electron microscopy (SEM) analysis showed resolution of the needle puncture, but not in the control group. Cell labeling of MCs upon injection of mixed MC:MSC suspensions revealed a gradual increase in the cell ratio.

CONCLUSIONS

The findings of this study establish that injection of MCs with or without MSCs enhances the cellularity of meniscus allograft to support early graft revival and remodeling.

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.

Mid-Term Clinical and Radiological Outcomes of Lateral Meniscal Allograft Transplantation with Suture-Only Fixation Plus Capsulodesis

Meniscal allograft transplantation (MAT) is an effective reconstructive procedure for treating a symptomatic postmeniscectomy syndrome. It consists of replacing the lost meniscal tissue aiming to improve the clinical outcomes and prevent progressive deterioration of the joint. The aim of this study was to evaluate meniscal graft survivorship and report on the radiographic (in terms of graft extrusion and joint space width and alignment) and the functional results through a midterm follow-up of lateral MAT performed with a soft tissue fixation technique after capsulodesis. In total, 23 patients who underwent lateral MAT as a single procedure were included. The Knee injury and Osteoarthritis Outcome Score, Lysholm, Tegner, and visual analog scale scales were used for patient assessment. Magnetic resonance imaging and a complete radiographic protocol were conducted to determine the degree of meniscal extrusion and the changes in the degree of osteoarthritis and coronal alignment. Assessments were performed after 2 and 7 years of follow-up. A significant improvement in all the scores, relative to preoperative values, was found after 7 years of follow-up. This improvement remained consistent throughout the first and second follow-up periods. A mean absolute extrusion of 2.2 mm ± 1.6 and an extrusion percentage of 28.0% ± 11.43 were found, with no significant differences throughout the follow-up periods. There was no statistically significant difference in terms of the frontal mechanical axis and joint space narrowing between the preoperative value and at the first and second follow-up periods. A survival rate of 85.7% was found after 7 years of follow-up. Capsulodesis results in a low degree of meniscal extrusion in isolated lateral MAT fixed with a suture-only technique, which is maintained after 7 years of follow-up, with a high graft survival index (>85%) and satisfactory results on the functional scales.

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.

Biomechanical Analysis Evaluating Meniscal Extrusion After Knotless Suture Anchor Fixation for Segmental Medial Meniscal Allograft Transplantation

Background

Segmental medial meniscal allograft transplantation (MAT) has been shown to restore knee biomechanics; however, stable fixation of the transplantation is critical to avoid extrusion and maximize healing.

Purpose

To evaluate the degree of meniscal extrusion and biomechanical function of segmental medial MAT performed with meniscocapsular sutures versus repair augmentation with knotless suture anchors.

Study Design

Controlled laboratory study.

Methods

Segmental midbody medial meniscectomy and subsequent segmental medial MAT were performed on 10 fresh-frozen cadaveric knees. The knees were then loaded in a dynamic tensile testing machine to 1000 N for 60 seconds at 0°, 30°, 60°, and 90° of flexion, and 4 conditions were tested: (1) intact, (2) segmental defect, (3) inside-out segmental repair, and (4) anchor plus inside-out segmental repair of the medial MAT. Meniscal extrusion was measured using high-fidelity ultrasound imaging. The mean contact area and the mean and peak contact pressures were assessed with submeniscal pressure-mapping sensors. Data from testing conditions were compared with 2-way repeated-measures analysis of variance, with pairwise comparison using the Bonferroni method.

Results

At 90° of flexion, the segmental defect state showed a higher degree of meniscal extrusion compared with all other states (P ≤ .012). There was no difference in the degree of meniscal extrusion between the intact state and the inside-out repair or anchor plus inside-out segmental repair states at all knee flexion angles (P > .05). There was no significant difference in the mean and peak contact pressures among the 4 states at all flexion angles except that at 0° of knee flexion there was significantly lower peak contact pressure at the medial compartment after anchor plus inside-out segmental repair compared with the segmental defect state (P = .048).

Conclusion

Meniscal extrusion was not significantly increased at any flexion angle after segmental resection. The addition of knotless anchors did not improve meniscal extrusion or contact pressures/area compared with capsular repair alone. The addition of knotless anchors did improve contact mechanics from the segmental defect state, but only at 0° of flexion.

Clinical Relevance

The addition of knotless suture anchors to segmental meniscal transplantation increased stabilization of the meniscus at full extension compared with repair with sutures alone. This increased stabilization may lead to better long-term outcomes.

Risk Factors for Graft Failure After Meniscal Allograft Transplantation: A Systematic Review and Meta-analysis

Background

Graft failure after meniscal allograft transplantation (MAT) may necessitate revision surgery or conversion to arthroplasty. A comprehensive understanding of the risk factors for failure after MAT of the knee may facilitate more informed shared decision-making discussions before surgery and help determine whether MAT should be performed based on patient risk.

Purpose

To perform a systematic review and meta-analysis of risk factors associated with graft failure after MAT of the knee.

Study Design

Systematic review; Level of evidence, 4.

Methods

The PubMed, OVID/Medline, and Cochrane databases were queried in October 2021. Data pertaining to study characteristics and risk factors associated with failure after MAT were recorded. DerSimonian-Laird binary random-effects models were constructed to quantitatively evaluate the association between risk factors and MAT graft failure by generating effect estimates in the form of odds ratios (ORs) with 95% CIs. Qualitative analysis was performed to describe risk factors that were variably reported.

Results

In total, 17 studies including 2184 patients were included. The overall pooled prevalence of failure at the latest follow-up was 17.8% (range, 3.3%-81.0%). In 10 studies reporting 5-year failure rates, the pooled prevalence of failure was 10.9% (range, 4.7%-23%). In 4 studies reporting 10-year failure rates, the pooled prevalence was 22.7% (range, 8.1%-55.0%). A total of 39 risk factors were identified, although raw data presented in a manner amenable to meta-analysis only allowed for 3 to be explored quantitatively. There was strong evidence to support that an International Cartilage Regeneration & Joint Preservation Society grade >3a (OR, 5.32; 95% CI, 2.75-10.31; P < .001) was a significant risk factor for failure after MAT. There was no statistically significant evidence to incontrovertibly support that patient sex (OR, 2.16; 95% CI, 0.83-5.64; P = .12) or MAT laterality (OR, 1.11; 95% CI, 0.38-3.28; P = .85) was associated with increased risk of failure after MAT.

Conclusion

Based on the studies reviewed, there was strong evidence to suggest that degree of cartilage damage at the time of MAT is associated with graft failure; however, the evidence was inconclusive on whether laterality or patient sex is associated with graft failure.

Signal intensity of lateral meniscal allografts deteriorates over time: a longitudinal MRI analysis during a minimum follow-up of 8 years

PURPOSE

To evaluate the serial change of magnetic resonance imaging (MRI) signal intensity (SI) of lateral meniscal allografts in a long-term period of > 8 years and to determine whether the SI change adversely affected clinical outcomes.

METHODS

Thirty-three lateral meniscal allograft transplantation (LMAT) patients with MRI taken > 8 years after surgery were included. The allograft was assessed using MRI at five serial time points (1, 2-4, 4-6, 6-8, and > 8 years after surgery), based on the following grading system: grade 1, globular increased SI not adjacent to the articular surface; grade 2, linear SI within the meniscus; and grade 3, increased SI extended to the articular surface. MRI evaluation was performed for three locations of the allograft (anterior horn, mid-body, and posterior horn), and the serial changes of allograft SI at each location were analyzed using the generalized estimating equation (GEE) with cumulative logit link function. The patients were classified according to SI change at each location (stationary group and deterioration group), and the two groups were compared in terms of clinical outcomes using the Lysholm score.

RESULTS

The mean follow-up duration was 9.2 ± 1.2 years. During that period, SI of the allograft deteriorated over time, regardless of the location (anterior horn, p = 0.034; mid-body, p = 0.002; posterior horn, p < 0.001). The amount of SI deterioration at each location of the graft differed with a borderline significance (p = 0.050, GEE), and the proportion of grade 3 SI was higher at the posterior horn (36.4%) than at the other locations at the last follow-up (p < 0.001, chi-square test). However, no significant differences in the Lysholm scores were found between the stationary group and the deterioration group at all locations.

CONCLUSION

SI of the meniscal allograft deteriorated over time at all locations during the long-term follow-up. Deterioration of the graft was more prominent at the posterior horn than at the other locations. SI deterioration did not adversely affect the clinical outcomes, which should be interpreted with caution, considering the small sample size of this study. In the prognosis of lateral MAT, SI deterioration at the posterior horn is a more determining factor than that at the other part of the allograft. Therefore, SI at the posterior horn needs to be examined with special concern.

LEVEL OF EVIDENCE

III.

Good clinical outcomes can be expected after meniscal allograft transplantation at 15 years of follow-up

PURPOSE

The aim of this study was to evaluate graft survivorship and report the functional and radiographic results of Meniscal allograft transplantation (MAT) throughout a minimum 15-year follow-up period.

METHODS

Fifty-one patients that had undergone an isolated MAT procedure during the period studied were included. The results were assessed with the Lysholm and Tegner scores as well as the Visual Analog Scale. Magnetic resonance imaging and a complete radiographic series were carried out to determine the degree of meniscal extrusion and joint space narrowing. A comparison was made between the radiological findings of the last follow-up, the 5-year mid-term follow-up and those from the preoperative period.

RESULTS

Thirty-eight patients were available for the final follow-up. The mean follow-up was 17.4 years. There were 23 (60.5%) medial menisci and 15 lateral menisci (39.4%). Meniscal extrusion increased from the 29.7% ± 14.9 obtained at the 5-year follow-up to the 72.5% ± 22.5 seen at the end of the follow-up (p = 0.0001). The joint space distance was almost unchanged from the initial evaluation (3.3 ± 1.5 mm) to the 5-year follow-up measurement (3.1 ± 1.7 mm, n.s.). However, it did decrease at the last follow-up (1.9 ± 1.5 mm, p < 0.05). The functional outcomes improved from the preoperative period to the mid-term follow-up and later worsened at the final follow-up. The mean preoperative Lysholm score at the initial follow-up was 61.5 ± 9.6, 86.9 ± 10.9 for the 5-year evaluation and stood at 77.4 ± 11.5 (p = 0.0001) at the final follow-up. Regarding the Tegner score, those pre-operative scores were compared to the ones at the last follow-up (median: 3; range 0-6 vs. 5.5; 3-6, respectively; p = 0.0001). The VAS went down from 6.6 ± 1.7 at the initial evaluation to 2.5 ± 1.9 at the final follow-up (p = 0.0001). The joint-space width remained unchanged from the initial evaluation (3.35 ± 1.5 mm) up to the 5-year follow-up measurement (3.1 ± 1.7 mm, n.s.). However, this joint-space distance had decreased by the last evaluation in the long-term follow-up (1.9 ± 1.4 mm, p < 0.05). Five patients (13.1%) presented with a MAT failure at 5 years, which was followed by extirpation of the meniscal graft. At the final follow-up, a total of 16 patients (42.1%) presented with a failure. At that time, there were 4 more MAT removals and seven patients that required a total knee replacement. The mean time to failure of the meniscal graft was 206.2 months ± 13.4 (18.0 years).

CONCLUSIONS

Meniscal allograft transplantation produces good functional results at a minimum 15-year follow-up. However, degenerative arthritis in the affected compartment progressed during that period.

LEVEL OF EVIDENCE

III.

Editorial Commentary: Restoring Native Meniscal Anatomy With Medial Meniscus Allograft Transplantation and Augmentation of the Meniscotibial Ligament May Decrease Meniscal Graft Extrusion

While studies have shown significant clinical improvement after medial meniscus allograft transplantation (MMAT) with good long-term graft survivorship, progression to osteoarthritis still occurs, even in the presence of intact grafts. Several factors can potentially explain the lack of chondroprotection despite graft survivorship, including meniscal degeneration, tearing, and remodeling after the initial procedure. A major factor contributing to progression of osteoarthritis is meniscal extrusion, which is seen in up to 60% of patients and seems to be more of an issue in medial meniscus transplantation compared to lateral and is present even immediately postoperatively. Grafts without extrusion provide protective effects similar to the native meniscus, while greater than 3 mm of extrusion leads to nearly complete loss of the protective effects. A reconstruction of the meniscotibial ligament, in addition to standard MMAT, may significantly decrease meniscal extrusion. Optimization of graft size, quality, and meniscal root positioning is best to prevent extrusion and restore native biomechanics.

Effect of ICRS Lesion Grade on Graft Survival After Medial Meniscal Allograft Transplantation: MRI-Based Objective Evaluation

BACKGROUND

Data are lacking regarding the survival rate after medial meniscal allograft transplantation (MAT) alone. Furthermore, little information is available about prognostic factors for graft survival that affect the outcomes of medial MAT.

PURPOSE

To investigate the prognostic factors and survival rate of allograft after medial MAT.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

The records of 78 consecutive patients who underwent primary medial MAT between 1996 and 2018 were reviewed. Kaplan-Meier survival analysis was performed to analyze the anatomic and clinical survival rates. Anatomic failure was defined as a tear covering >50% of the allograft or unstable peripheral rim. Clinical failure was considered Lysholm score <65 or need for additional surgery such as meniscal repair, revision MAT, realignment osteotomy, and meniscectomy for >50% of the allograft. Patient factors affecting anatomic and clinical failure were analyzed.

RESULTS

The mean follow-up period was 6.9 ± 5.3 years (range, 2-21 years). Anatomic failure was noted in 19 patients (24.4%), and none of these patients had a persistent poor Lysholm score of <65; of these, 2 patients who underwent meniscal repair also had clinical failure. Clinical failure was noted in 7 patients (9.0%); 4 patients had Lysholm score <65, 2 patients underwent meniscal repair, and 1 patient underwent realignment osteotomy. The estimated 10-year anatomic and clinical survival rates were 73.89% and 87.90%, respectively. Anatomic survival was significantly associated with only high-grade International Cartilage Regeneration & Joint Preservation (ICRS) lesion (ICRS grade 3 or 4) (hazard ratio, 3.171; 95% CI, 1.124-8.944; P = .029). However, the clinical survival rate was not significantly associated with any factors. Patients with low-grade ICRS lesion (ICRS grade 0, 1, or 2) showed a higher estimated 10-year anatomic survival rate compared with patients with high-grade ICRS lesions (87.6% vs 63.3%, respectively; P = .022).

CONCLUSION

Low-grade ICRS lesion was associated with higher anatomic survival rate after medial MAT. In patients with high-grade ICRS lesions, the clinical outcome might be good; however, the status of an allograft might be poor. The surgeon should be aware of this and explain to the patient that close observation is necessary.

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.

Risk Factors Affecting the Survival Rate of Collagen Meniscal Implant for Partial Meniscal Deficiency: An Analysis of 156 Consecutive Cases at a Mean 10 Years of Follow-up

BACKGROUND

Collagen meniscal implant (CMI) is a biologic scaffold that can be used to replace meniscus host tissue after partial meniscectomy. The short-term results of this procedure have already been described; however, little is known about risk factors for failure.

PURPOSE

To determine the factors that predict failure of meniscal scaffold implantation in a large series of patients treated at a single institution and to better define the indications for surgery.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

The analysis included 186 consecutive patients with a minimum 5-year follow-up who underwent CMI scaffold implantation or combined procedures. Patients' characteristics and details of the surgery were obtained via chart review. Patients with a Lysholm score <65 were considered to have experienced clinical failure. Surgical failure was defined as partial or total scaffold removal.

RESULTS

The final analysis included 156 patients (84%) at a mean follow-up of 10.9 ± 4.3 years. The patients' mean age at surgery was 42.0 ± 11.1 years, and the survival rate was 87.8%. Subgroup analysis identified Outerbridge grade 3-4 (Hazard ratio [HR], 3.8; P = .004) and a lateral meniscal implant (HR, 3.2; P = .048) as risk factors for failure. The survival rate was 90.4% for medial implants and 77.4% for lateral implants. An Outerbridge grade 3-4 (HR, 2.8; P < .001) and time from meniscectomy to scaffold >10 years (HR, 2.8; P = .020) were predictive of surgical or clinical failure.

CONCLUSION

CMI for partial meniscal deficiency provided good long-term results, with 87.8% of the implants still in situ at a mean 10.9 years of follow-up. Outerbridge grade 3-4, lateral meniscal implants, and longer time from the meniscectomy to implantation of the CMI were identified as risk factors for clinical and surgical failure.

Clinical significance and management of meniscal extrusion in different knee pathologies: a comprehensive review of the literature and treatment algorithm

The menisci are crescent-shaped, fibrocartilaginous structures that play a crucial role in the load transition and distribution of the contact forces along the tibiofemoral articulation. Meniscal extrusion (ME) is a radiological finding, especially in magnetic resonance imaging (MRI) scans, for which there has been growing interest in recent years. ME, in the coronary plane, is defined as the maximum distance of the most distal end of the meniscus from the border of the tibial plateau, where the tibial eminences are the most prominent, without taking into account the osteophytes. Although there is still controversy in the literature in respect of the optimal cutoff value, a threshold of 3 mm is considered significant. ME has no specific clinical finding or sign and it is encountered in many knee pathologies. It is associated with either rapidly progressive knee osteoarthritis or early onset of knee osteoarthritis and increased morbidity. In this review, we delineate the clinical significance of ME in various knee pathologies, as well as when, why and how it should be managed. To the best of our knowledge, this is the first study to elaborate on these topics.

Lateral Meniscus Allograft Transplantation in Combination with BMAC (Bone Marrow Aspirate Concentrate) Injection: Biologic Augmentation of the Allograft

Meniscal allograft transplantation (MAT) has proven successful in relieving joint pain and providing functional improvement in patients who have undergone subtotal or total meniscectomy. Bone marrow aspirate concentrate (BMAC) is a biological adjuvant that was shown in the literature to be effective in treating cartilage damage and muscle-tendon tissue problems. The aim of the study is the concomitant use of MAT and BMAC, which are both considered biological treatments and would be beneficial in clinical practice.

Biomechanical Analysis of Segmental Medial Meniscal Transplantation in a Human Cadaveric Model

BACKGROUND

Meniscal deficiency has been reported to increase contact pressures in the affected tibiofemoral joint, possibly leading to degenerative changes. Current surgical options include meniscal allograft transplantation and insertion of segmental meniscal scaffolds. Little is known about segmental meniscal allograft transplantation.

PURPOSE

To evaluate the effectiveness of segmental medial meniscal allograft transplantation in the setting of partial medial meniscectomy in restoring native knee loading characteristics.

STUDY DESIGN

Controlled laboratory study.

METHODS

Ten fresh-frozen human cadaveric knees underwent central midbody medial meniscectomy and subsequent segmental medial meniscal allograft transplantation. Knees were loaded in a dynamic tensile testing machine to 1000 N for 20 seconds at 0°, 30°, 60°, and 90° of flexion. Four conditions were tested: (1) intact medial meniscus, (2) deficient medial meniscus, (3) segmental medial meniscal transplant fixed with 7 meniscocapsular sutures, and (4) segmental medial meniscal transplant fixed with 7 meniscocapsular sutures and 1 suture fixed through 2 bone tunnels. Submeniscal medial and lateral pressure-mapping sensors assessed mean contact pressure, peak contact pressure, mean contact area, and pressure mapping. Two-factor random-intercepts linear mixed effects models compared pressure and contact area measurements among experimental conditions.

RESULTS

The meniscal-deficient state demonstrated a significantly higher mean contact pressure than all other testing conditions (mean difference, ≥0.35 MPa; P < .001 for all comparisons) and a significantly smaller total contact area as compared with all other testing conditions (mean difference, ≤140 mm²; P < .001 for all comparisons). There were no significant differences in mean contact pressure or total contact area among the intact, transplant, or transplant-with-tunnel groups or in any outcome measure across all comparisons in the lateral compartment. No significant differences existed in center of pressure and relative pressure distribution across testing conditions.

CONCLUSION

Segmental medial meniscal allograft transplantation restored the medial compartment mean contact pressure and mean contact area to values measured in the intact medial compartment.

CLINICAL RELEVANCE

Segmental medial meniscal transplantation may provide an alternative to full meniscal transplantation by addressing only the deficient portion of the meniscus with transplanted tissue. Additional work is required to validate long-term fixation strength and biologic integration.

Association Between Meniscal Allograft Tears and Early Surgical Meniscal Allograft Failure

BACKGROUND

Meniscal allograft transplantation (MAT) has become a viable treatment option for patients with symptomatic meniscal deficiency. Some patients experience early surgical meniscal allograft failure attributed to causes that have not yet been sufficiently clarified.

PURPOSE

To evaluate the prevalence, types, and distribution of arthroscopically confirmed meniscal allograft tears and the associated effect on surgical meniscal allograft survival.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients undergoing MAT with a minimum 2-year follow-up were retrospectively reviewed. Descriptive and surgical data were collected. Type and location of arthroscopically confirmed meniscal allograft tears were recorded and compared between medial and lateral allografts and suture-only and bone block fixation. A survival analysis was conducted to evaluate the effect of meniscal allograft tears on surgical meniscal allograft survival.

RESULTS

This study included 142 patients (54% male; mean ± SD age, 29.6 ± 10.4 years) with a mean follow-up of 10.3 ± 7.5 years. The prevalence of meniscal allograft tears was 32%, observed at a median of 1.2 years (interquartile range, 2.8 years) after MAT. The posterior horns were most frequently affected, followed by the posterior roots, midbodies, anterior horns, and anterior roots. The most frequently observed tear types were root tears (43%), followed by longitudinal, horizontal, radial, complex, bucket-handle, and meniscocapsular separation tears. A statistically significant association was found between meniscal allograft tear types and fixation techniques (P = .027), with root tears predominant after suture-only as compared with bone block fixation (57% vs 22%). Patients with meniscal allograft root tears were a mean of 5.4 years (95% CI, 1.6-9.2 years; P = .007) younger than were patients without root tears. The 1-year surgical meniscal allograft survival rate was significantly lower for torn versus intact meniscal allografts (75% vs 99%; P < .001).

CONCLUSION

Meniscal allograft root tears were predominant, associated with younger patient age, and more often observed when using the suture-only fixation technique versus the bone block fixation technique. Torn meniscal allografts were associated with early surgical graft failure when compared with intact meniscal allografts, resulting in a significantly lower 1-year survival rate.

Increased MRI Signal Intensity of Allografts in the Midterm Period After Meniscal Allograft Transplant: An Evaluation of Clinical Significance According to Location and Morphology

Background:

Magnetic resonance imaging (MRI) is an effective tool for objective evaluation after meniscal allograft transplant (MAT). Little is known about the association between MRI features of allograft and clinical outcomes.

Purpose/Hypothesis:

To assess the degree and location of signal intensity (SI) as well as the morphology of allografts on MRI after MAT and evaluate the association between clinical outcomes and MRI features in the midterm period. It was hypothesized that a high SI accompanied by a deformed allograft in specific locations on MRI would be associated with inferior clinical outcomes.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Included were patients who underwent MAT with fresh-frozen allografts and had >3 years of follow-up with 3.0-T MRI scans. Allograft status was assessed by SI on MRI as grade 0 (normal), grade 1 (globular increased SI not adjacent to the articular surface), grade 2 (linear SI within the meniscus), or grade 3 (increased SI extended to the articular surface). Allograft morphology was assessed by the presence of distorted contours. Clinical outcomes were evaluated using the Lysholm score. The association between clinical outcomes and MRI findings was assessed by multiple linear regression analysis.

Results:

A total of 138 patients (156 MAT procedures: 132 lateral, 24 medial) with a mean follow-up period of 55.4 ± 19.9 months (range, 36-110 months) were enrolled in this study. Grade 3 SI was observed in the posterior meniscus root and posterior third of the allograft in 39 (25%) and 62 (39.7%) MATs, respectively. Among the 62 MATs with grade 3 SI in the posterior third of the allograft, 34 (54.8%) were accompanied by distorted allograft contour. The presence of grade 3 SI with distorted contour in the posterior third of the allograft was significantly associated with inferior outcomes (β = –6.5 [95% CI, –12.5 to –0.5]; P < .035), as was the presence of grade 3 SI in the posterior meniscus root (β = –5.5 [95% CI, –10.5 to –0.4]; P < .034).

Conclusion:

On MRI evaluation in the midterm period after MAT, grade 3 SIs of the meniscal allograft were observed in about a third of the cases, and the association with clinical outcomes was dependent on the specific location and morphology of the allograft on MRI.

Meniscal Salvage: Where We Are Today

The menisci are fibrocartilaginous semilunar structures in the knee that provide load support. Injury to the meniscus alters its load sharing and biomechanical profile. Knee arthroscopy with meniscus débridement is the most common orthopaedic surgical procedure done in the United States. The current goals of meniscal surgery are to preserve native meniscal tissue and maintain structural integrity. Meniscal preservation is critical to maintain the normal mechanics and homeostasis of the knee; however, it is not always feasible because of the structure's poor blood supply and often requires removal of irreparable tissue with meniscectomy. Efforts have increasingly focused on the promotion of meniscal healing and the replacement of damaged menisci with allografts, scaffolds, meniscal implants, or substitutes. The purpose of this article was to review current and future meniscal salvage treatments such as meniscus transplant, synthetic arthroplasty, and possible bioprinted meniscus to allow patients to maintain quality of life, limit pain, and delay osteoarthritis.

Meniscal Regenerative Scaffolds Based on Biopolymers and Polymers: Recent Status and Applications

Knee menisci are structurally complex components that preserve appropriate biomechanics of the knee. Meniscal tissue is susceptible to injury and cannot heal spontaneously from most pathologies, especially considering the limited regenerative capacity of the inner avascular region. Conventional clinical treatments span from conservative therapy to meniscus implantation, all with limitations. There have been advances in meniscal tissue engineering and regenerative medicine in terms of potential combinations of polymeric biomaterials, endogenous cells and stimuli, resulting in innovative strategies. Recently, polymeric scaffolds have provided researchers with a powerful instrument to rationally support the requirements for meniscal tissue regeneration, ranging from an ideal architecture to biocompatibility and bioactivity. However, multiple challenges involving the anisotropic structure, sophisticated regenerative process, and challenging healing environment of the meniscus still create barriers to clinical application. Advances in scaffold manufacturing technology, temporal regulation of molecular signaling and investigation of host immunoresponses to scaffolds in tissue engineering provide alternative strategies, and studies have shed light on this field. Accordingly, this review aims to summarize the current polymers used to fabricate meniscal scaffolds and their applications in vivo and in vitro to evaluate their potential utility in meniscal tissue engineering. Recent progress on combinations of two or more types of polymers is described, with a focus on advanced strategies associated with technologies and immune compatibility and tunability. Finally, we discuss the current challenges and future prospects for regenerating injured meniscal tissues.

Prognostic Factors to Determine Survivorship of Meniscal Allograft Transplant: A Systematic Review

Background:

There is much room for improvement and optimization of meniscal allograft survivorship.

Purpose:

To understand prognostic factors for survivorship using evidence-based selection criteria in order to identify patients who would best benefit from meniscal allograft transplant (MAT).

Study Design:

Systematic review; Level of evidence, 4.

Methods:

We conducted this systematic review to analyze prognostic factors for survivorship of MAT. The Cochrane Central Register, PubMed publisher, Embase.com, and Web of Science databases were searched through August 8, 2019. Included studies entailed patients of any age who received MAT with a reported association between prognostic factors and survivorship of the allograft. Two reviewers independently screened all titles and abstracts for eligibility, extracted the data, assessed the risk of bias using the Newcastle-Ottawa Scale, and performed a best-evidence synthesis.

Results:

The review included 18 studies with a total of 1920 patients. The mean follow-up time was 6.0 years (range, 2.1-11.2 years). A total of 20 prognostic factors were identified and shown to be associated with survivorship of MAT. Strong evidence was found that severe cartilage damage was associated with poor survivorship. Strong evidence was also found showing that sex, knee compartment, surgical side, concomitant anterior cruciate ligament (ACL) reconstruction, and concomitant osteotomy for malalignment had no effect on survivorship. Moderate evidence was found that body mass index (<36), tobacco use, and arthroscopic versus open procedure had no influence on survivorship. Conflicting evidence was found that older age and kissing cartilage lesions (lesions on both the femur and tibia vs on a single side) decreased survivorship.

Conclusion:

Severe cartilage damage decreases the survivorship of MAT. Concomitant ACL reconstruction and osteotomy showed no relationship to survivorship. Many determinants showed conflicting and limited evidence. Older age may be of interest and should be further studied.

Segmental Meniscus Allograft Transplantation

Meniscal tears treated with partial meniscectomies have been shown to significantly increase contract pressures within the tibiofemoral joint, and a complete focal meniscal deficiency may render the entirety of the meniscus functionally incompetent. Although various techniques of meniscal transplantation have been described, these techniques may require the excision of a considerable amount of healthy meniscal tissue. Furthermore, failures continue to frequently occur. Therefore, attempts to restoring normal knee kinematics and biomechanical forces are essential. Segmental meniscus allograft transplantations may offer the advantage of a robust repair by both maintaining knee biomechanics and biology while maximizing preservation of native meniscal tissue. Also, most meniscal deficiency involves only a portion of the meniscus, and thus we developed this technique to segmentally transplant only the deficient portion. The purpose of this Technical Note is to describe a technique of segmental medial meniscus allograft transplantation in a patient with focal medial meniscus deficiency.

Microstructure Analysis and Reconstruction of a Meniscus

OBJECTIVE

To analyze the characteristics of menicus microstructure and to reconstruct a microstructure-mimicing 3D model of the menicus.

METHODS

Human and sheep meniscus were collected and prepared for this study. Hematoxylin-eosin staining (HE) and Masson staining were conducted for histological analysis of the meniscus. For submicroscopic structure analysis, the meniscus was first freeze-dried and then scanned by scanning electron microscopy (SEM). The porosity of the meniscus was determined according to SEM images. A micro-MRI was used to scan each meniscus, immersed in distilled water, and a 3D digital model was reconstructed afterwards. A three-dimensional (3D) resin model was printed out based on the digital model. Before high-resolution micro-CT scanning, each meniscus was freeze-dried. Then, micro-scale two-dimensional (2D) CT projection images were obtained. The porosity of the meniscus was calculated according to micro-CT images. With micro-CT, multiple 2D projection images were collected. A 3D digital model based on 2D CT pictures was also reconstructed. The 3D digital model was exported as STL format. A 3D resin model was printed by 3D printer based on the 3D digital model.

RESULTS

As revealed in the HE and Masson images, a meniscus is mostly composed of collagen, with a few cells disseminated between the collagen fiber bundles at the micro-scale. The SEM image clearly shows the path of highly cross-linked collagen fibers, and massive pores exist between the fibers. According to the SEM images, the porosity of the meniscus was 34.1% (34.1% ± 0.032%) and the diameters of the collagen fibers were varied. In addition, the cross-linking pattern of the fibers was irregular. The scanning accuracy of micro-MRI was 50 μm. The micro-MRI demonstrated the outline of the meniscus, but the microstructure was obscure. The micro-CT clearly displayed microfibers in the meniscus with a voxel size of 11.4 μm. The surface layer, lamellar layer, circumferential fibers, and radial fibers could be identified. The mean porosity of the meniscus according to micro-CT images was 33.92% (33.92% ± 0.03%). Moreover, a 3D model of the microstructure based on the micro-CT images was built. The microscale fibers could be displayed in the micro-CT image and the reconstructed 3D digital model. In addition, a 3D resin model was printed out based on the 3D digital model.

CONCLUSION

It is extremely difficult to artificially simulate the microstructure of the meniscus because of the irregularity of the diameter and cross-linking pattern of fibers. The micro-MRI images failed to demonstrate the meniscus microstructure. Freeze-drying and micro-CT scanning are effective methods for 3D microstructure reconstruction of the meniscus, which is an important step towards mechanically functional 3D-printed meniscus grafts.

Predictors of Meniscal Allograft Transplantation Outcome: A Systematic Review

This systematic review investigates factors associated with outcomes after meniscal allograft transplantation (MAT). The PubMed, Scopus, and Cochrane Central Register databases were used to search relevant articles in April 2018. Studies that evaluated at least one association between a factor and outcomes were extracted. Of 3,381 titles, 52 studies were finally analyzed. Data about predictors, patient-reported outcome scores (PROMs), and failure rates were extracted for quantitative and qualitative analysis. A total of 3,382 patients and 3,460 transplants were identified. Thirty different predictors were reported in the current MAT literature, 18 of which by at least two studies. Subgroup analysis showed that lateral MAT had higher postoperative values than medial MAT in Lysholm's (p = 0.0102) and International Knee Documentation Committee (IKDC; p = 0.0056) scores. Soft tissue fixation showed higher postoperative IKDC scores than bone fixation (p = 0.0008). Fresh frozen allografts had higher Lysholm's scores (p < 0.0001) and showed significantly lower failure rates (p < 0.0001) than cryopreserved allografts. Age (p < 0.015, β = 0.80), sex (p < 0.034, β  =  - 8.52), and body mass index (BMI; p < 0.014, β = -4.87) demonstrated an association with PROMs in the regression model. Qualitative analysis found moderate evidence that a higher number of previous procedures in the same knee are an independent predictor of transplant failure. Conflicting evidence was found with regard to chondral damage, time from meniscectomy, smoke, sport level, worker's compensation status, and preoperative Lysholm's score as predictors of outcomes. Our review suggests that the ideal candidate to undergo MAT may be a young male of normal weight with no previous knee surgeries, treated with a lateral isolated procedure. However, MAT is associated with good outcomes in the majority of patients with many of the PROMs requiring further study to determine their direct effects on long-term outcomes. This study is a systematic review and reflects level of evidence IV.

Editorial Commentary: Medial and Lateral Meniscus Allografts Using Bone Plug Fixation in Patients Without Advanced Arthritis Have 80% Positive Outcomes at 10 Years

Meniscal allograft transplantation (MAT) for symptomatic knees after meniscectomy decreases pain and often improves function, but it does not replicate a normal meniscus. The ability of MAT to delay arthritic changes is an ongoing area of study, and it is known that outcomes and graft survivorship deteriorate with longer follow-up. Recommended indications are symptomatic patients after meniscectomy with mild (or at most moderate) degenerative changes and absence of (or surgically corrected) associated malalignment or ligament deficiency. When these indications are followed, 80% of patients improve, with survivorship of 83% at 10 years and 56.2% at 20 years. Medial or lateral MAT shows no difference with respect to graft survivorship or patient-reported outcome measures. Meniscus allografts fixed with bone have less graft extrusion than soft tissue fixation alone. While MAT can be beneficial in an arthritic knee in the short term, the survivorship in knees with advanced arthritis is much smaller, with an extensive rehabilitation requirement, and there is a limited supply of meniscal allograft tissue.

Medial and Lateral Meniscus Allograft Transplantation Showed No Difference With Respect to Graft Survivorship and Clinical Outcomes: A Comparative Analysis With a Minimum 2-Year Follow-Up

PURPOSE

To compare the differences with respect to clinical and graft survivorship and patient-reported outcomes (PROs) between lateral (LMAT) and medial (MMAT) meniscus allograft transplantation.

METHODS

Patients having a primary MAT between 1998 and 2016 were enrolled. The inclusion criteria were (1) patients who had a minimum 2-year follow-up and (2) patients who had magnetic resonance imaging (MRI) >2 years after surgery. Knees with localized grade 4 articular cartilage lesions >3 cm² at the time of MAT were excluded. Clinical failure was defined as follows: modified Lysholm score <65, meniscectomy >50% of the graft, meniscectomy to the meniscocapsular junction zone, conversion to revision MAT, or realignment osteotomy or arthroplasty. Graft failure was defined as follows: tears involving >50% of the graft or unhealed peripheral rim observed on MRI. Kaplan-Meier survival analysis with log-rank test was used to compare survivorship between LMAT and MMAT. Patient-reported outcomes were compared based on the Hospital for Special Surgery, modified Lysholm, and International Knee Documentation Committee subjective scores collected preoperatively and at the final follow-up.

RESULTS

A total of 299 knees (249 LMAT, 50 MMAT, mean age 33.0 ± 9.8 years) were included. Twenty clinical [2 MMAT (4.0%), 18 LMAT (7.2%)] and 24 graft [2 MMAT (4.0%), 22 LMAT (8.8%)] failures were identified. The mean clinical follow-up period was 63.1 ± 43.1 months (range 2 to 248), and MRI follow-up period was 62.6 ± 43.8 months (range 2 to 248). No significant differences in clinical and graft survivorship were found between the LMAT and MMAT groups (P = .481, P = .271, respectively). PROs preoperatively and at last follow-up also showed no significant difference between the groups.

CONCLUSION

No significant differences in clinical survivorship, graft survivorship, and PROs were found between the LMAT and MMAT groups.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

High rate of return-to-play following meniscal allograft transplantation

PURPOSE

In recent years, meniscal allograft transplantation (MAT) has been established as an effective option for young patients with symptomatic meniscus insufficiency with goals of functional improvement and joint preservation. Currently, there is little available information on return-to-play among patients in this cohort. The purpose of this study is to systematically review the literature and to evaluate the reported rehabilitation protocols, return-to-play guidelines, and subsequent rates of return-to-play following MAT.

METHODS

MEDLINE, EMBASE and the Cochrane Library were searched according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to find studies on MAT. Studies were included if they reported return-to-play data or rehabilitation protocols. The rate and timing of return-to-play was assessed. The rehabilitation protocols were recorded, including time to start range of motion (ROM), full ROM, partial weight bearing (WB), and full WB.

RESULTS

Overall, 67 studies met the inclusion criteria. Eleven studies, including 624 patients, reported 483 out of 624 patients (77.4%) returning to play, with 326 out of a reported 475 patients (68.6%) returning to the same/higher level, at a mean time to return of 9.0 months. There was significant variability in the reported rehabilitation protocols, but the most commonly reported time to begin ROM exercises was within the first week by 42 out of 60 studies (70.0%) and full ROM at 8 weeks by 18 out of 46 studies (39.1%). Partial weight bearing was most commonly begun in the fourth week by 20 out of 46 studies (43.5%), and for full WB the sixth week by 43 out of 65 studies (66.1%). Time elapsed following surgery was the most commonly reported criteria for return-to-play by 44 out of 48 studies (91.6%), with 6 months being the most common time point utilized by 17 out of 45 studies (37.8%). A small proportion of studies, 16 out of 48 (33.3%), advised against returning to competitive/collision sports altogether following MAT.

CONCLUSIONS

In conclusion, there is a high rate of return-to-play following MAT, with the majority of patients returning to the same level of play. However, there is significant variability in reported rehabilitation protocols, and poor-quality reporting in return-to-play criteria in the literature indicates a need for further study and the development of an evidence-based consensus statement for this patient population. The results from this study can be used to better inform patients on their expected outcomes and provide a more informed consent process.

LEVEL OF EVIDENCE

IV.

Reoperation Rates Following Meniscus Transplantation Using the Truven Database

PURPOSE

The purpose of this study was to determine the (1) reoperation rate and (2) 30-day complication rate in a large insurance database.

METHODS

The Truven Database was queried for subjects that underwent meniscus allograft transplantation (Current Procedural Terminology code 29868) in the outpatient setting with minimal 2-year follow-up. Patients without confirmed laterality and patients that underwent concomitant ligament reconstruction were excluded. Reoperation was defined by ipsilateral knee procedure after the index surgery. The 30-day postoperative complication rates were assessed using International Classification of Diseases, 9th Revision, Clinical Modification codes.

RESULTS

A total of 284 patients (mean age of 26.2 ± 10.4 years; 49.6% females) were included in this study with mean follow up of 43.2 ± 19.2 months. One hundred and sixty-seven subjects (58.8%) undergoing meniscus allograft transplantation underwent reoperation at an average of 11.9 ± 12.2 months postoperatively. There was a low number of subjects that required ipsilateral unicompartmental knee arthroplasty and total knee arthroplasty postoperatively (0.7% and 1.1%, respectively). The overall 30-day complication rate following meniscus allograft transplantation was 1.4%.

CONCLUSIONS

Patients undergoing meniscus allograft transplantation have a 58.8% reoperation rate at final follow up with low (1.4%) 30-day complication rates in a large insurance database.

LEVEL OF EVIDENCE

Level IV, case series.

Editorial Commentary: Meniscal Allograft Transplantation Results in Unacceptable Reoperation Rates According to a Large Claims Database-However, Reoperations Do Not Necessarily Equal Failure

The biomechanical and clinical importance of the meniscus is now well-accepted. In accordance with this understanding, recent focus has shifted toward techniques that preserve the meniscus, including repair and meniscal allograft transplantation (MAT). Although MAT is a technically challenging procedure, evidence has suggested that it restores knee kinematics and tibiofemoral contact pressures, which may subsequently delay or prevent cartilage degeneration. Recent literature has reported concerns as to the high rate of reoperations after MAT, bringing into question the clinical utility of this procedure and its place in the realm of knee preservation. However, reoperations do not necessarily equal failure. MAT is a temporizing procedure that, when aligned with patient expectations, is valuable.

Editorial Commentary: Long-Term Survivorship of Knee Meniscal Transplant Surgery-The Importance of Patient-Reported Outcomes With Magnetic Resonance Imaging Demonstration of Retained Meniscal Transplant Function

The altered knee joint function and symptomatic state in younger patients after meniscectomy and progressive tibiofemoral arthritis remain an important unsolved treatment dilemma. Meniscal allograft transplantation has evolved as an acceptable treatment because there are few (if any) other options. The procedure is effective in most patients, who experience a decrease in tibiofemoral pain and improved knee function, even allowing a return to light recreational activities. However, biological remodeling of the implant occurs over time, with replacement of the complex circumferential and radial fibers with disorganized collagen tissues and altered cellular and proteoglycan components that affects load bearing and negates chondroprotective function. Positive patient outcomes may still be reported even with the loss of meniscal transplant function on magnetic resonance imaging giving a false-positive survivorship analysis. Repeated surgical procedures are frequent by 10 years. Patients are advised that meniscal allograft transplant surgery, although beneficial in the short term to buy time, is not curative.

Meniscal Allograft Survivorship and Outcomes 20 Years After Implantation

PURPOSE

To evaluate meniscal allograft survivorship and outcomes 20 years after implantation.

METHODS

Fifty-six meniscal allograft patients at a minimum 20 years following implantation comprised the study group. Forty-eight (85.7%) were able to be contacted regarding the function of their knee and if any additional surgeries were performed.

RESULTS

Of the 48 patients, 21 required surgical treatment of the graft. Thirteen patients had isolated partial meniscectomy. Eight patients had knee arthroplasty with 1 having prior partial graft removal and one also had a high tibial osteotomy. The average time to arthroplasty was 12.7 years. The graft survivorship was 56.2%. The activity levels at follow-up varied widely, but in general did not deteriorate compared to those preoperatively. Only 1 patient stated they would not have undergone the procedure.

CONCLUSIONS

Meniscal allografts were able to provide subjective improvement at 20 years after surgery and while not as durable as the native meniscus, the overall graft survivorship was 56.2% after implantation.

LEVEL OF EVIDENCE

Retrospective case series, Level of evidence IV.

Long-term Outcomes and Survivorship of Fresh-Frozen Meniscal Allograft Transplant With Soft Tissue Fixation: Minimum 10-Year Follow-up Study

BACKGROUND

Meniscal allograft transplant (MAT) is considered an effective procedure for reducing pain and improving knee function. Nevertheless, the current knowledge regarding the results of MAT is limited to short- to mid-term follow-up studies, especially for arthroscopic techniques.

PURPOSE

To evaluate the long-term clinical outcomes, reoperations, and failures with a minimum follow-up of 10 years after fresh-frozen MAT performed arthroscopically with soft tissue fixation.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 46 patients (age, 36.6 ± 10.6 years; 36 male, 10 female) who underwent medial MAT (n = 27) or lateral MAT (n = 19) with a minimum 10-year follow-up were evaluated with the Lysholm score, Knee injury and Osteoarthritis Outcome Score (KOOS), visual analog scale for pain, and Tegner score. Surgical failure was defined as the need for partial or total graft removal (meniscectomy or knee replacement), and clinical failure was defined as the need for partial or total graft removal in addition to a poor Lysholm score (<65 points) at final follow-up. Survival analysis was performed with Kaplan-Meier curve, and clinical scores were analyzed based on the Patient Acceptable Symptom State (PASS) for MAT.

RESULTS

10-year survival and clinical data were available for 38 patients. Because 6 meniscectomies were required, the rate of survival free from surgical failure was 91% at 5 years and 86% at 10 years. Lower survival was reported in lateral MAT (73%) compared with medial MAT (96%). Because a further 4 patients had poor Lysholm scores, the rate of survival free from surgical and clinical failure was 87% at 5 years and 70% at 10 years. The average Lysholm score at final follow-up was 82 ± 20, and 60% to 82% of patients achieved PASS of the various KOOS subscales. The Tegner score and the KOOS Sport score significantly decreased from mid-term to long-term evaluation (P < .001 and P < .05, respectively). Other KOOS subscales and the Lysholm score remained stable at long-term evaluation. No significant differences were found between isolated MAT or combined MAT regarding subjective scores, surgical failures, or clinical failures.

CONCLUSION

Up to 10 years after surgery, 86% of fresh-frozen MATs with soft tissue fixation were still in situ, and satisfactory clinical results were present for about 70% of patients. Decline of clinical outcomes from midterm to long term was noted only in sports-related scores. A higher number of overall reoperations was noted in female patients, whereas a higher risk of failure was present in the patients with lateral MAT.

Illustrative review of knee meniscal tear patterns, repair and replacement options, and imaging evaluation

This review article aims to reinforce anatomical concepts about meniscal tears while linking associated treatment options. The main teaching points start with the basic meniscal anatomy and key differences between the medial and lateral menisci. Subsequently, various meniscal tear patterns along with their associated history and physical exam findings will be discussed with corresponding illustrations and MR images. Additional discussion will involve the different surgical repair techniques (with arthroscopic correlates), their indications with pertinent imaging findings, imaging related to previous meniscal tear repairs, and novel surgical techniques. Lastly, keys to evaluating for retear with an emphasis on MRI arthrogram findings will be reviewed. While each of these topics is not discussed in totality, the key points of the review article will enforce key concepts and help radiologists evaluate the menisci on imaging.

Meniscus transplantation-prospective assessment of clinical results in two, five and ten year follow-up

PURPOSE

The authors present clinical results in patients following transplantation of deep-frozen menisci within ten years following the surgery.

METHODS

A cohort of 46 patients who were transplanted altogether 49 menisci was subject to prospective study following six months, two, five and ten years after meniscus transplantation. For subjective assessment, we used KOOS, IKDC and Lysholm scores; objective assessment was based on load X-ray examination of the operated knee at two, five and ten years after the surgery, MRI examination of 34 patients in the interval of two and ten years after the operation, control arthroscopy was performed in 23 patients eight of whom suffered a new injury.

RESULTS

All 38 patients who have completed ten year follow-up without any new injury of the operated joint demonstrated statistically significant improvement of mobility in the period of six months and two, five and ten years following the meniscal transplantation. Further follow-up demonstrated different results in patients with a new injury and without a new injury of the operated knee joint. In eight patients (17.3%), the follow-up was disturbed by a new injury of the operated joint within three to eight years after the meniscal transplantation. In three patients with the damaged meniscal transplant, a cartilage deterioration from degree II to degree IIIa was found. In second-look arthroscopy, the patients with no injury showed signs of the improved condition of cartilage by one degree according to ICRS classification on average. The MRI imaging showed relatively frequent (47%) extrusion of the anterior and medial part of meniscus (2.5-3.8 mms) without the followed-up dynamics of changes at two and ten years after the surgery.

CONCLUSION

All patients in the selected cohort proved the positive benefit of meniscus transplant when it comes to the improvement of clinical symptoms and improvement of mobility of the operated knee joint. The higher mobility following the transplantation compared to the activity prior to the surgery could have contributed to a new injury of the operated joint in 17% of the patients in the cohort.

Likelihood of Return to Duty Is Low After Meniscal Allograft Transplantation in an Active-duty Military Population

BACKGROUND

Meniscal allograft transplantation (MAT) is considered a viable surgical treatment option in the symptomatic, postmeniscectomy knee and as a concomitant procedure with ACL revision and articular cartilage repair. Although promising outcomes have recently been reported in active and athletic populations, MAT has not been well-studied in the high-demand military population.

QUESTIONS/PURPOSES

(1) What proportion of active-duty military patients who underwent MAT returned to full, unrestricted duty? (2) What demographic and surgical variables, if any, correlated with return to full, unrestricted duty?

METHODS

Between 2005 and 2015, three fellowship-trained sports surgeons (TMD, SJS, BDO) performed 110 MAT procedures in active-duty military patients, of which 95% (104 patients) were available for follow-up at a minimum 2 years (mean 2.8 ± SD 1.1 year). During the study period, indications for MAT generally included unicompartmental pain and swelling in a postmeniscectomized knee and as a concomitant procedure when a meniscal-deficient compartment was associated with either an ACL revision reconstruction or cartilage repair. Demographic and surgical variables were collected and analyzed. The primary endpoints were the decision for permanent profile activity restrictions and military duty termination by a medical board. The term "medical board" implies termination of military service because of medical reasons. We elected to set statistical significance at p < 0.001 to reduce the potential for spurious statistical findings in the setting of a relatively small sample size.

RESULTS

Forty-six percent (48 of 104) of eligible patients had permanent profile activity restrictions and 50% (52 of 104) eventually had their military duty terminated by a military board. Only 20% (21 of 104) had neither permanent profile activity restrictions nor medical-board termination and were subsequently able to return to full duty, and only 13% (13 of 104) continued unrestricted military service beyond 2 years after surgery. Age, gender, tobacco use, and BMI did not correlate with return to full duty. Combat arms soldiers were less likely to have permanent profile activity restrictions (odds ratio 4.76 [95% confidence interval 1.93 to 11.8]; p = 0.001) and were more likely to return to full duty than soldiers in support roles (OR 0.24 [95% CI 0.09 to 0.65]; p = 0.005), although these findings did not reach statistical significance. Officers were more likely to return to full duty than enlisted soldiers at more than 2 years after surgery (OR 17.44 [95% CI 4.56 to 66.65]; p < 0.001). No surgical variables correlated with return-to-duty endpoints.

CONCLUSIONS

Surgeons should be aware of the low likelihood of return to military duty at more than 2 years after MAT and counsel patients accordingly. Based on this study, MAT does not appear to be compatible with continued unrestricted military duty for most patients.

LEVEL OF EVIDENCE

IV, therapeutic study.

Meniscus Repair and Regeneration: A Systematic Review from a Basic and Translational Science Perspective

Meniscus injuries are among the most common athletic injuries and result in functional impairment in the knee. Repair is crucial for pain relief and prevention of degenerative joint diseases like osteoarthritis. Current treatments, however, do not produce long-term improvements. Thus, recent research has been investigating new therapeutic options for regenerating injured meniscal tissue. This review comprehensively details the current methodologies being explored in the basic sciences to stimulate better meniscus injury repair. Furthermore, it describes how these preclinical strategies may improve current paradigms of how meniscal injuries are clinically treated through a unique and alternative perspective to traditional clinical methodology.

Clinical outcomes and survival rate of autologous chondrocyte implantation with and without concomitant meniscus allograft transplantation: 10- to 15-year follow-up study

PURPOSE

The purpose of this study was to compare the clinical outcomes and survival rate of autologous chondrocyte implantation (ACI) with or without concomitant meniscus allograft transplantation (MAT).

METHODS

Patients who underwent ACI of the medial or lateral femoral condyle with or without concomitant MAT were retrospectively reviewed. There were 14 patients (mean age, 31.2 ± 9.9 years) who underwent isolated ACI and 19 patients who underwent ACI with concomitant MAT (mean age, 34.8 ± 8.4 years). The International Knee Documentation Committee (IKDC) subjective score, Lysholm score, Tegner activity score, and 10- to 15-year survival rate were compared between groups.

RESULTS

All clinical scores showed significant improvement postoperatively in both groups. At final follow-up, the IKDC subjective score was superior in isolated ACI (75.8 ± 18.4) compared to ACI with MAT (61.0 ± 16.6, p = 0.024). The Lysholm score was also higher in isolated ACI (77.5 ± 19.1) than ACI with MAT (62.5 ± 18.1, p = 0.029). The Tegner activity score did not differ between treatments (isolated ACI, 5.3 ± 1.1; ACI with MAT, 4.5 ± 1.3; p = 0.072). The 15-year survival rate for isolated ACI was higher than that of ACI with concomitant MAT (69.6% vs 50.2%), but this difference was not statistically significant (p = 0.19).

CONCLUSIONS

ACI with concomitant MAT did not restore clinical outcomes as much as isolated ACI. There was a trend for the long-term survival rate to be greater in isolated ACI than ACI with MAT. These results should be considered in planning for the treatment of focal chondral defect with meniscus deficiency.

LEVEL OF STUDY

Retrospective comparative trial; level of evidence, 3.

Lateral Meniscal Allograft Transplantation With Bone Block and Suture-Only Techniques Partially Restores Knee Kinematics and Forces

BACKGROUND

The ability of lateral meniscal allograft transplantation (MAT) to improve knee stability and the meniscal load-bearing function in patients after meniscectomy is critical for surgical success.

PURPOSE

To compare the effects of 2 lateral MAT fixation techniques-bone block and suture only-on knee kinematics and forces.

STUDY DESIGN

Controlled laboratory study.

METHODS

With a robotic testing system, loads were applied during flexion on 10 fresh-frozen cadaveric knees: 134-N anterior tibial load + 200-N axial compression, 5-N·m internal tibial + 5-N·m valgus torques, and 5-N·m external tibial + 5-N·m valgus torques. Kinematic data were recorded for 4 knee states: intact, total lateral meniscectomy, lateral MAT bone block, and lateral MAT suture-only fixation. In situ force in the anterior cruciate ligament and resultant forces in the lateral meniscus and in the meniscal allograft were quantified via the principle of superposition. A repeated measures analysis of variance was used to analyze variations in kinematics and forces at 0°, 30°, 60°, and 90° of knee flexion. Significance was set at P < .05.

RESULTS

When anterior loads were applied, a decrease in medial translation of the tibia that was increased after total lateral meniscectomy was observed at 30°, 60°, and 90° of knee flexion for both the lateral MAT bone block (54.2%, 48.0%, and 50.0%) and the MAT suture-only (50.0%, 40.0%, and 34.6%) fixation techniques (P < .05). Yet, most of the increases in knee kinematics after lateral meniscectomy were not significantly reduced by either lateral MAT technique (P > .05 for each MAT technique vs the total lateral meniscectomy state). Resultant forces in the meniscal allograft were 50% to 60% of the resultant forces in the intact lateral meniscus in response to all loading conditions at all flexion angles (P < .05). Overall, no significant differences between lateral MAT techniques were observed regarding kinematics and forces (P > .05).

CONCLUSION

Lateral MAT partially restored medial translation of the tibia, and the resultant forces in the meniscal allograft were only 50% to 60% of the intact lateral meniscus forces in the cadaver model. In the majority of testing conditions, no significant changes of the in situ force in the anterior cruciate ligament were observed. Surgeons should consider the potential benefits of lateral MAT when deciding the appropriate treatment for symptomatic patients after lateral meniscectomies. Both lateral MAT techniques functioned similarly.

CLINICAL RELEVANCE

The load-bearing function of the meniscal allograft observed in this study may be beneficial in ameliorating the short- and long-term disability associated with lateral meniscal deficiency.

The Meniscus in Normal and Osteoarthritic Tissues: Facing the Structure Property Challenges and Current Treatment Trends

The treatment of meniscus injuries has recently been facing a paradigm shift toward the field of tissue engineering, with the aim of regenerating damaged and diseased menisci as opposed to current treatment techniques. This review focuses on the structure and mechanics associated with the meniscus. The meniscus is defined in terms of its biological structure and composition. Biomechanics of the meniscus are discussed in detail, as an understanding of the mechanics is fundamental for the development of new meniscal treatment strategies. Key meniscal characteristics such as biological function, damage (tears), and disease are critically analyzed. The latest technologies behind meniscal repair and regeneration are assessed.

Treatment options for the symptomatic post-meniscectomy knee

PURPOSE

To provide a current review on the evidence for management of the symptomatic meniscus-deficient knee.

METHODS

A literature review was performed detailing the natural history and origin of symptoms in a meniscus-deficient knee, in addition to strategies for non-surgical management, meniscus scaffolds, meniscus allograft transplantation (MAT), isolated cartilage repair, unloading osteotomies, meniscus prosthesis, and joint replacements which were revealed as treatment possibilities.

RESULTS

Meniscus deficiency was recognized to lead to an early onset knee osteoarthritis (OA). A subset of patients develop post-meniscectomy syndrome: dull and nagging pain after a short pain-free interval subsequently to meniscectomy, which can be accompanied by transient effusions. Evidence for non-surgical management of post-meniscectomy knee pain is lacking. Two available meniscus scaffolds, indicated for symptomatic segmental meniscus deficiency, show pain relief at mid-term follow-up, and effect on joint preservation is unclear. MAT represents a durable solution for sub/total meniscus deficiency (80% survival at 10 years), but it is still considered a temporary solution for post-meniscectomy pain. MAT may also reduce the progression of OA. Isolated cartilage repair without a meniscus reconstruction is commonly performed, but better results were reported with preserved or reconstructed menisci. Osteotomies are used in the combination of misaligned knee and meniscus reconstruction or as pain solution for irreversible unilateral knee structural changes following a meniscectomy. Polycarbonate-urethane medial meniscus prosthesis is currently undergoing clinical trial. Joint replacements should be limited to later stages of post-meniscectomy OA.

CONCLUSIONS

Post-meniscectomy pain syndrome and post-meniscectomy knee OA are common findings after meniscus resection. Short-term pain relief is provided by non-surgical management, mid-term pain relief by meniscus scaffolds, and long-term relief by MAT, though each has differing indications. In later stages, osteotomies and joint replacements are indicated.

LEVEL OF EVIDENCE

IV.

Meniscus allograft transplantation: indications, techniques and outcomes

New indications for meniscal allograft transplantation (MAT) are being added, but the general expert opinion is that it is still a procedure reserved for symptomatic meniscal loss.

Lateral MAT has better clinical outcomes and less failure risk compared to medial MAT.

Ideal conditions (low-grade chondral lesions) make MAT a more survivable and successful procedure.

Meniscal extrusion after MAT is common and does not seem to alter results.

Midterm survivorship of a MAT is reported to be 85–90%, while long-term survivorship decreases to 50–70% depending on chondral status and concomitant procedures.

Even if the procedure is a success, there are high possibilities of not being able to resume sports activities.

Cite this article: EFORT Open Rev 2019;4:115-120. DOI: 10.1302/2058-5241.4.180052