Transplantation of viable meniscal allograft. Survivorship analysis and clinical outcome of one hundred cases

Viable Vitreous Grafts of Whole Porcine Menisci for Transplant in the Knee and Temporomandibular Joints

The shortage of suitable donor meniscus grafts from the knee and temporomandibular joint (TMJ) impedes treatments for millions of patients. Vitrification offers a promising solution by transitioning these tissues into a vitreous state at cryogenic temperatures, protecting them from ice crystal damage using high concentrations of cryoprotectant agents (CPAs). However, vitrification's success is hindered for larger tissues (>3 mL) due to challenges in CPA penetration. Dense avascular meniscus tissues require extended CPA exposure for adequate penetration; however, prolonged exposure becomes cytotoxic. Balancing penetration and reducing cell toxicity is required. To overcome this hurdle, a simulation-based optimization approach is developed by combining computational modeling with microcomputed tomography (µCT) imaging to predict 3D CPA distributions within tissues over time accurately. This approach minimizes CPA exposure time, resulting in 85% viability in 4-mL meniscal specimens, 70% in 10-mL whole knee menisci, and 85% in 15-mL whole TMJ menisci (i.e., TMJ disc) post-vitrification, outperforming slow-freezing methods (20%-40%), in a pig model. The extracellular matrix (ECM) structure and biomechanical strength of vitreous tissues remain largely intact. Vitreous meniscus grafts demonstrate clinical-level viability (≥70%), closely resembling the material properties of native tissues, with long-term availability for transplantation. The enhanced vitrification technology opens new possibilities for other avascular grafts.

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.

Fresh Versus Frozen Meniscal Allograft Transplant: Revisit or Redundant? A Systematic Review

BACKGROUND

Fresh-frozen allografts are the current standard in meniscal allograft transplant (MAT) surgery, due to their availability, ease of preservation, and affordability. However, fresh-frozen grafts are associated with several clinical challenges such as graft shrinkage and extrusion, among many others.

PURPOSE

To present the current knowledge on the use of fresh meniscal allografts, presenting whether benefits associated with fresh grafts provide sufficient evidence to support their use in clinical practice.

STUDY DESIGN

Systematic review; Level of evidence, 5.

METHODS

A comprehensive search was conducted with keywords listed below. After an initial screening on title and abstract, full-text articles were assessed with the inclusion criteria.

RESULTS

A total of 78 studies matched the inclusion criteria. Literature and preclinical studies indicated that fresh meniscal allografts are beneficial for maintaining mechanical properties, graft ultrastructure, and matrix metabolism due to the presence of viable cells. Therefore, fresh allografts may address common complications associated with fresh-frozen MAT. To overcome challenges associated with both fresh-frozen and fresh allografts, a group has studied treating fresh-frozen allografts with a cell-based injection therapy.

CONCLUSION

Fresh meniscal allografts pose several challenges including limited availability, demanding preservation procedures, and high costs. Although the role of viable cells within meniscal allografts remains controversial, these cells may be vital for maintaining tissue properties.

Clinical and Radiological Outcomes of Medial Meniscal Allograft Transplantation Combined With Realignment Surgery

BACKGROUND

The outcomes of medial meniscal allograft transplantation (MMAT) combined with high tibial osteotomy (HTO) compared with isolated MMAT remain unclear.

PURPOSE

To compare the clinical and radiological results of MMAT combined with HTO and isolated MMAT.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

This retrospective study included 42 consecutive patients, who were divided into group M (isolated MMAT; n = 22) and group H (MMAT combined with HTO with a varus angle >3°; n = 20). Group differences in subjective knee scores, isokinetic muscle strength test, and radiological outcomes (Kellgren-Lawrence grade, mechanical axis, graft extrusion, graft status, and articular cartilage loss) were compared.

RESULTS

The mean follow-up period was 29.2 ± 4.9 months and 27.4 ± 5.3 months for groups M and H, respectively. The Lysholm score improved from 55.4 ± 9.5 to 81.3 ± 9.7 and from 52.6 ± 8.9 to 84.2 ± 10.2 in groups M and H, respectively (both P < .001). The International Knee Documentation Committee subjective score improved from 51.4 ± 10.3 to 79.6 ± 9.4 and from 49.3 ± 11.4 to 81.4 ± 8.3 in groups M and H, respectively (both P < .001). Both groups showed no significant differences in subjective knee scores and isokinetic extensor strength at the final follow-up. The rate of preoperative and postoperative high International Cartilage Regeneration & Joint Preservation Society grade (≥3) did not differ between the 2 groups. Group M showed greater coronal graft extrusion than did group H (3.3 ± 0.7 mm vs 2.7 ± 0.8 mm; P = .014); the rate of pathologic graft extrusion (≥3 mm) was not higher in group M (40.9%) than in group H (20%) with the number of patients available (P = .143). Both groups showed no significant difference in the graft status. Graft tears were observed in 2 patients (9%) in group M and 1 patient (5%) in group H (P = .607).

CONCLUSION

Clinical scores significantly improved after isolated MMAT and MMAT combined with HTO compared with preoperative values, and their short-term outcomes were similar. Postoperative graft extrusion was greater in patients who underwent isolated MMAT, implying that active correction of varus alignment during MMAT may help in intra-articular biomechanics.

10-Year Survival and Clinical Improvement of Meniscal Allograft Transplantation in Early to Moderate Knee Osteoarthritis

BACKGROUND

Meniscal allograft transplantation (MAT) is a viable option for patients experiencing unicompartmental knee pain after total or subtotal meniscectomy. Nonetheless, caution is recommended when suggesting this procedure in the presence of knee osteoarthritis (OA) because of the higher risk of poor survival and outcomes.

PURPOSE/HYPOTHESIS

The purpose was to document the long-term survival of MAT performed as a salvage procedure in patients with knee OA. The hypothesis was that MAT would significantly reduce pain and increase the function of the affected joint at a long-term follow-up compared with the preoperative condition, with a low number of failures and knee replacement surgeries.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 47 patients (37 men and 10 women) with symptomatic knee OA (Kellgren-Lawrence grades 2 or 3) treated with MAT were evaluated at baseline, 5 years, and a minimum 10-year final follow-up (11.1 ± 1 years) using the Lysholm score, the visual analog scale for pain, the Knee injury and Osteoarthritis Outcome Score subscales, and the Tegner score. A total of 44 patients had undergone previous surgeries. Patient satisfaction, revision surgeries, and failures were also recorded.

RESULTS

A statistically significant improvement was observed in all clinical scores from the baseline assessment to the final follow-up. The Lysholm score improved significantly from 46.4 ± 17.2 at the preoperative assessment to 77.7 ± 20.4 at the intermediate follow-up (P < .001), with a significant decrease at the final follow-up (71 ± 23.3; P = .018). A similar trend was reported for the visual analog scale scale for pain, Knee injury and Osteoarthritis Outcome Score, and Tegner score, with no complete recovery to the previous sports activity level. A total of 33 patients required concurrent procedures, such as anterior cruciate ligament reconstructions, osteotomies, and cartilage procedures. Five patients underwent reoperation and were considered surgical failures, while 15 patients presented a clinical condition of <65 of the Lysholm score and were considered clinical failures. Among these, 4 patients were considered both surgical and clinical failures.

CONCLUSION

MAT surgery has proven to be a valid option for improving pain and function even in OA joints (Kellgren-Lawrence grades 2 or 3), yielding satisfactory results despite a worsening clinical outcome in the long-term follow-up. Therefore, based on the data from this study, orthopaedic surgeons may consider recommending MAT as a salvage procedure even in knees affected by early to moderate OA, while advising patients that the need for combined interventions could potentially reduce graft survival.

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.

Clinical Outcomes of Medial Meniscal Allograft Transplantation With or Without High Tibial Osteotomy: A Case-Control Study Up to 8 Years of Follow-up

BACKGROUND

Satisfactory clinical results of meniscal allograft transplantation (MAT) have been reported in recent years. However, it remains unclear whether the clinical outcomes of MAT when combined with an osteotomy are inferior to those of isolated MAT.

PURPOSE

To compare the survival rates and clinical outcomes of patients who received isolated medial MAT with those of patients undergoing medial MAT combined with high tibial osteotomy (HTO).

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 55 patients underwent arthroscopic medial MAT using the soft tissue technique and HTO (mean age, 41.3 ± 10.4 years; 9 female); after fuzzy case-control matching on demographics, 55 controls who underwent isolated medial MAT were also included. Survival analyses were performed using the Kaplan-Meier method with surgical failure, clinical failure (Lysholm score, <65), and reoperation as endpoints. Subjective clinical scores were collected preoperatively and at the final follow-up.

RESULTS

The mean follow-up time was 5.4 years, up to 8 years. All outcomes significantly improved at the last follow-up (P < .001). No differences were identified between MAT and MAT + HTO groups preoperatively and at the last follow-up (P > .05). At the final follow-up, 8 of 55 (14.5%) of the MAT + HTO patients and 9 of 55 (16.4%) of the MAT patients had a Lysholm score <65 (P = .885). Overall, 90% of the patients declared they would repeat the surgery regardless of the combined procedure. Surgical failure was identified in 6 of 110 (5.5%) patients: 5 of 55 (9.1%) in the MAT + HTO group and 1 of 55 (1.8%) in the MAT group (P = .093). Clinical failure was identified in 19 of 110 (17.3%) patients: 11 of 55 (20%) in the MAT + HTO group and 8 of 55 (14.5%) in the MAT group (P = .447). A significantly lower survivorship from surgical failure was identified in the MAT + HTO group (hazard ratio, 5.1; P = .049), while no differences in survivorship from reoperation and clinical failure were identified (P > .05).

CONCLUSION

Patients undergoing medial MAT + HTO showed similar clinical results to patients undergoing isolated medial MAT at midterm follow-up, and thus a surgically addressed malalignment does not represent a contraindication for medial MAT. However, the need for a concomitant HTO is associated with a slightly higher failure rate over time.

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.

High tibial osteotomy is equally effective for varus malaligned knees with either virgin or wrecked medial meniscus: An age and gender-matched secondary analysis of a Francophone Arthroscopy Society Symposium

INTRODUCTION

Despite the growing concept of meniscal preservation, partial meniscectomy could be the definitive procedure in specific scenarios. And total meniscectomy was once before a frequent procedure, with current sequelae of degenerate knees. High tibial osteotomy (HTO) is an effective treatment for patients suffering from unicompartmental degenerative changes, and substantial deformities. However, it is yet to be answered, whether HTO is similarly effective in both post-meniscectomy knees and knees with not previously operated meniscus.

HYPOTHESIS

Outcomes of HTO is similar with or without previous history of total or subtotal meniscectomy.

METHODS

This study compared the clinical and radiological outcomes of 41 patients who received HTO and had no previous history of surgery in the ipsilateral knee (group I), and 41 age, and gender-matched patients who had meniscectomy surgery in the ipsilateral knee (group II). Preoperatively and postoperatively, all patients were clinically evaluated; the visual analogue scale scores, Tegner activity score, and the Western Ontario and Macmaster University scores were reported. Radiographically, osteoarthritis grade and pre- and postoperative parameters were reported, including hip-knee-ankle angle, femoral mechanical angle, medial proximal tibial angle, joint line convergence angle, proximal posterior tibial angle, and limb length discrepancy. Perioperative details and complications were reported.

RESULTS

A total of 82 patients were included; group I (n=41) and group II (n=41). The mean age was 51.18±8.64 (27-68) and 90.24% were male. The duration since the onset of symptoms was longer in group II vs. group I, 43.34±41.03 versus 38.07±36.11months respectively. No significant differences in the clinical evaluation between the two groups with a greater proportion of patients demonstrating moderate degenerative changes. Similar preoperative and postoperative radiographic parameters were reported, in group I, Δ HKA was 7.19±4.14 versus 7.65±3.16 in group II. Preoperative pain VAS scores were slightly higher in group II vs. group I, 79.23±26.35 vs. 76.31±24.45, respectively. However, postoperatively, the pain scores significantly improved in group I vs. group II, 22.84±3.65 vs. 41.69±17.33, respectively. Tegner activity scores and WOMAC scores were comparable between both groups preoperatively and postoperatively. Only the WOMAC function scores were better in group I when compared to group II, 26.13±25.84 versus 20.01±17.98. All patients returned to work at an average of 0.82±0.38months.

CONCLUSION

Knee preservation with high tibial osteotomy is equally effective in managing unicompartmental degenerative changes in varus malaligned knees with either no previous history of meniscal surgeries or where a meniscal sacrifice was inevitable, either with subtotal or total meniscectomy.

LEVEL OF EVIDENCE

III, retrospective case-control study.

Effects of Lateral Opening-Wedge Distal Femoral Osteotomy on Meniscal Allograft Transplantation: A Biomechanical Evaluation

Background

Lateral meniscal deficiency with valgus malalignment increases the rate of lateral compartment osteoarthritis. Lateral meniscal allograft transplantation (LMAT) with a concomitant varus-producing opening-wedge distal femoral osteotomy (DFO) is an option yet to be evaluated biomechanically.

Purpose/Hypothesis

The purpose of this study was to clarify the biomechanical effects of the realignment procedure in the setting of LMAT. We hypothesized that (1) given the dependence of the lateral compartment on the lateral meniscus, a DFO and increasing degrees of varus would be insufficient to restore lateral compartment pressures to normal from a lateral meniscus-deficient state, and that (2) LMAT would restore lateral compartment pressures to the intact state while DFO would decrease lateral compartment pressures for any given state of the meniscus.

Study Design

Controlled laboratory study.

Methods

Ten cadaveric knees underwent opening-wedge varus-producing DFO secured by an external fixator. Anatomic alignment was standardized to 6° of mechanical valgus, and each joint was tested in full extension. Submeniscal placement of thin film pressure sensors allowed for the recording of contact pressure, peak contact pressure, and contact area. The specimens were loaded on a biaxial dynamic testing machine with loading angles between 9° valgus and 6° varus of mechanical alignment. Conditions tested included intact meniscus, meniscal deficiency, and meniscal transplantation.

Results

Isolated varus-producing DFO to 6° in the meniscus-deficient state failed to restore joint pressures and contact areas to the intact state, with significant changes in mean contact pressure (175%), mean peak contact pressure (135%), and contact area (-41%) (all P < .05 vs intact), while LMAT restored all outcome measures (all P > .05 compared with intact). After LMAT, every additional 1° of DFO correction contributed to a decrease in the mean contact pressure, peak pressure, and contact area of 5.6% (-0.0479 N/mm²), 5.9% (-0.154 N/mm²), and 1.4% (-6.99 mm²) for the lateral compartment and 7.3% (+0.034 N/mm²), 12.6% (+0.160 N/mm²), and 4.3% (+20.53 mm²) for the medial compartment, respectively.

Conclusion

Isolated DFO was inadequate to restore load distribution in meniscus-deficient knees, while concomitant LMAT restored near normal forces and improved the lateral compartment biomechanical profile.

Clinical Relevance

Our findings support the concomitant use of LMAT and varus-producing DFO in the setting of lateral meniscal deficiency with valgus malalignment. This study provides tools for the orthopaedic surgeon to individualize the correction for each patient.

Meniscus Size Differs Between Patient and Donor Populations for Meniscus Allograft Transplantation

Purpose

To determine the extent of variability in meniscus size and anthropometric data between donors (supply) and patients (demand), to evaluate potential factors that may contribute to size discrepancies, and to determine whether the discrepancies lead to longer patient wait times.

Methods

Lateral and medial meniscal measurements, anthropometric data, and time to match a donor graft were extracted from a tissue supplier database. The frequency and distribution of meniscus size were analyzed. Body mass index (BMI), relative meniscus area, body mass to meniscus area index, and height to meniscus area index were compared between patient and donor pools via χ² tests and independent samples t-test. The effect of size on time to match was analyzed using analysis of variance and post-hoc Tukey test.

Results

The lateral meniscus patient population showed a greater frequency of larger size requirements compared to the donor population (P < .001) and the medial meniscus patient population showed a higher frequency of smaller meniscus size requirements (P < .001). The medial meniscus analysis showed significantly smaller meniscus areas (P < .001) in the patient population contributing to the observed trend of an increased body mass to meniscus area index and height to meniscus area index. The time to match a donor meniscus was affected by the patient meniscus size.

Conclusions

This analysis demonstrates variations in frequency of meniscus sizes between donor and patient populations. This variation is attributed to differences in anthropometric data between patient and donor populations. This work identifies a mismatch between demand and supply for certain patient sizes contributing to longer times to match.

Clinical Relevance

This work associated donor and patient mismatches with longer wait times. This can be useful for patient counseling as well as provide a framework to determine whether there are solutions within the current meniscus donor pool that can be used to meet this clinical need.

Survivorship and Reoperation of 324 Consecutive Isolated or Combined Arthroscopic Meniscal Allograft Transplants Using Soft Tissue Fixation

BACKGROUND

Meniscal allograft transplant (MAT) is an effective treatment for relieving symptoms and improving knee function in patients who experience symptomatic unicompartmental knee pain after a previous meniscectomy. However, the literature contains a paucity of studies assessing the survival rate and prognostic factors of soft tissue MAT.

PURPOSE

To report the survivorship of a large, single-center cohort of consecutive patients treated with arthroscopic MAT using soft tissue technique and to investigate variables that could potentially influence failures and outcomes.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Consecutive MAT procedures totaling 364 performed in a single institution between June 2004 and April 2019 were screened and assessed for eligibility. Subjective clinical scores (Lysholm score, Tegner activity scale, and visual analog score) were collected preoperatively and at 2, 5, 7, and 10 years of follow-up. Two survival analyses were performed using Kaplan-Meier curves, with surgical failure (defined as any graft revision) and clinical failure (defined as a Lysholm score <65 points) used as endpoints. Univariate analyses were performed using reoperations, surgical failure, clinical failure, and different demographic and surgical characteristics as endpoints.

RESULTS

A total of 324 consecutive patients were evaluated at a mean follow-up 5.7 ± 3.0 years. Of these, 189 (58%) underwent an associated surgical procedure. A total of 22 patients (6.8%) were considered to have experienced surgical failure, and no predictors of surgical failure were identified based on the relevant variables. When all patients were considered, a significant improvement in all of the patient-reported outcome measures was present between the preoperative assessment and the last follow-up (P < .001), with no significant decrease over time. Moreover, 70 (21.6%) patients were considered to have experienced clinical failure; the need for concurrent cartilage procedures (odds ratio, 0.16; P = .001) and anterior cruciate ligament (ACL) reconstruction (odds ratio, 0.40; P = .059) were predictors of failure. Finally, a lower survival rate was reported in female patients compared with male patients (49% vs 69%, respectively; P = .007) and in patients who required cartilage surgery (P = .014). In particular, patients who required cartilage surgery showed nearly half the survival rate compared with those with required no cartilage procedures at 10-year follow-up (36.4% vs 71%, respectively; P = .029).

CONCLUSION

Female sex and the need to combine MAT with a cartilage procedure or ACL reconstruction could result in an increased rate of clinical failure at midterm follow-up.

Compressive mechanical properties of vitrified porcine menisci are superior to frozen and similar to fresh porcine menisci

The common practice of freezing meniscal allograft tissue is limited due to the formation of damaging ice crystals. Vitrification, which eliminates the formation of damaging ice crystals, may allow the mechanical properties of meniscal allograft tissue to be maintained during storage and long-term preservation. The primary objective of this study was to investigate the differences between fresh, frozen, and vitrified porcine lateral menisci examining compressive mechanical properties in the axial direction. Unconfined compressive stress-relaxation testing was conducted to quantify the mechanical properties of fresh, frozen and vitrified porcine lateral menisci. The compressive mechanical properties investigated were peak and equilibrium stress, secant, instantaneous and equilibrium modulus, percent stress-relaxation, and relaxation time constants from three-term Prony series. Frozen menisci exhibited inferior compressive mechanical properties in comparison with fresh menisci (significant differences in peak and equilibrium stress, and secant, instantaneous and equilibrium modulus) and vitrified menisci (significant differences in peak stress, and secant and instantaneous modulus). Interestingly, fresh and vitrified menisci exhibited comparable compressive mechanical properties (stress, modulus and relaxation parameters). These findings are significant because (1) vitrification was successful in maintaining mechanical properties at values similar to fresh menisci, (2) compressive mechanical properties of fresh menisci were characterized providing a baseline for future research, and (3) freezing affected mechanical properties confirming that freezing should be used with caution in future investigations of meniscal mechanical properties. Vitrification was superior to freezing for preserving compressive mechanical properties of menisci which is an important advance for vitrification as a preservation option for meniscal allograft transplantation.

Failure rates and clinical outcomes of synthetic meniscal implants following partial meniscectomy: a systematic review

Background

Meniscal injury is one of the most common indications for knee surgery. The advent of meniscal repair techniques has facilitated meniscal preservation in suitable cases. Meniscal substitution with scaffolds may be advantageous following partial meniscal resection. There are three main scaffolds in current clinical use; Collagen Meniscal Implant (CMI Stryker Corporation, Kalamazoo, MI, USA), Actifit (Actifit, Orteq Ltd, London, UK) and NUsurface (Active Implants, LLC). The purpose of this systematic review was to compare clinical outcomes and failure rates of patients who have had implantation with these meniscal scaffolds.

Methods

MEDLINE and EMBASE databases were searched for studies that included patients who had surgical implantation with Actifit or CMI. Eligibility criteria included papers that described both clinical outcomes and failure rates of these implants, a mean follow up of 5 years and studies published in English. A Google search was also performed to identify any grey literature.

Results

Five Level IV studies were found for Actifit. One Level II, one Level III and four Level IV studies were found for the CMI implant. One Level II study was identified for the NUsurface scaffold with a follow-up 12 months and was included for completeness. Overall, 262 patients were treated with Actifit, 109 with CMI and 65 with NUsurface. Failure rates for Actifit were 18% (range 6.3–31.8%) with a mean follow up of 66.8 months, and for CMI 6.5% (range 0–11.8%) with a mean follow up of 97.1 months. The NUsurface failure rate was 16.9% at 12 months. Clinical outcomes such as VAS, Tegner and Lysholm scores improved significantly post-operatively. However, there was a high volume of concurrent procedures, such as anterior cruciate ligament reconstructions and high tibial osteotomies in each study group; 118 (45%) for Actifit and 53 (45%) for CMI.

Conclusion

The evidence for meniscal scaffold use is insufficient to suggest that they could potentially improve clinical outcomes in patients post-meniscal resection. This is largely due to the high proportion of concurrent procedures performed at index procedure for both CMI and Actifit. On the basis of current evidence, the use of meniscal scaffolds as a sole treatment for partial meniscal defects cannot be recommended, owing to the relatively high failure rate and paucity of clinical data.

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.

Tensile mechanical properties of vitrified porcine menisci are superior to frozen and similar to fresh porcine menisci

Vitrification inhibits crystallization of ice and may allow the mechanical properties of menisci to be preserved for transplantation without the damaging consequences of ice crystals formed during freezing. The primary objective of this study was to investigate the differences between fresh, frozen, and vitrified porcine lateral menisci examining tensile mechanical properties along the circumferential-peripheral, circumferential-central, longitudinal, and radial orientations. The secondary objective was to investigate the variations in the tensile mechanical properties of menisci comparing the circumferential-peripheral orientation to the three other orientations: circumferential-central, longitudinal, and radial. Quasi-static tensile testing was conducted to quantify the tensile mechanical properties of fresh, frozen and vitrified menisci. Ultimate tensile strength of frozen menisci were significantly decreased compared with fresh and vitrified menisci along three orientations: circumferential-peripheral, longitudinal, and radial. Along the circumferential-central orientation, tensile modulus of frozen menisci was significantly decreased compared with fresh menisci. The mechanical properties of vitrified menisci were comparable to fresh menisci along all four orientations. For all menisci (fresh, frozen and vitrified), ultimate tensile strength and failure strain along the circumferential-peripheral orientation were significantly increased compared with the three other orientations. Freezing was detrimental to the mechanical properties of menisci but vitrification likely avoided the negative effects of freezing thereby preserving mechanical properties that were comparable to fresh menisci. The findings of this study revealed that vitrification was superior to freezing for preserving mechanical properties of meniscal tissue; hence, vitrification is likely to be a competitive alternative to freezing for meniscal transplantation in the future.

Meniscal allograft transplantation shows a mismatch between anatomic and clinical failures

PURPOSE

Clinical results of meniscal allograft transplantation (MAT) are not always consistent with graft status. This study aimed to investigate (1) the degree and pattern of mismatch between anatomic and clinical failures in MAT and (2) preoperative factors associated with the mismatch.

METHODS

Two hundred and ninety-eight consecutive patients who underwent primary medial or lateral MAT during 2004-2015 were reviewed. Anatomic failure was defined as an allograft showing meniscal tear involving > 50% of the graft or unstable peripheral rim. Clinical failure included poor Lysholm score of < 65 and any requirement for re-operations such as arthroplasty, realignment osteotomy, revision MAT, and meniscectomy (more than 50% of the graft or to the zone of meniscocapsular junction). Failure cases were categorised according to the type of failure as follows: (1) type 1, anatomic failure followed by clinical failure; (2) type 2, anatomic failure did not lead to clinical failure; and (3) type 3, clinical failure without anatomic failure. Preoperative factors including age, sex, body mass index, MAT compartment, time from previous meniscectomy, alignment, cartilage status, and accompanying procedures were analysed according to the failure type.

RESULTS

Forty (13.4%) patients showed anatomical or clinical failure during the median (25th-75th percentile) follow-up duration of 47 (30-72) months (range 24-178 months). Eleven (3.7%) patients showed both anatomical and clinical failure (type 1 failure). Seventeen (5.7%) patients showed anatomic failure that did not lead to clinical failure (type 2 failure). Twelve (4.0%) patients failed clinically without meniscal tear (> 50% of graft) or unstable peripheral rim (type 3 failure). Comparative analyses among failure types found a significant difference in MAT compartment (p = 0.01). In particular, the incidence of type 3 failure was higher in medial than in lateral MAT (p = 0.003).

CONCLUSION

A notable number of failure cases of MAT showed a mismatch between anatomic and clinical failures. Even with anatomic failure, MAT did not always lead to poor clinical scores or re-operations, whereas MAT could have poor results without substantial allograft problems. Therefore, both anatomic and clinical aspects should be considered when evaluating MAT. In particular, type 3 failure occurred more frequently in medial than in lateral MAT.

LEVEL OF EVIDENCE

III.

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

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.

Outcomes, Complications, and Reoperations After Meniscal Allograft Transplantation

Background:

Outcomes following meniscal allograft transplantation (MAT) are an evolving topic.

Purpose:

To review clinical outcomes in younger, previously active patients who underwent an isolated MAT or MAT plus any osteotomy. Concurrent surgeries, complications, and graft survivorship are presented.

Study Design:

Case series; Level of evidence, 4.

Methods:

Inclusion criteria included having undergone MAT with a minimum of 1 year of follow-up with at least 1 of the following patient-reported outcome (PRO) measures collected pre- and postoperatively: visual analog scale for pain, Knee injury and Osteoarthritis Outcome Score (KOOS), the Western Ontario and McMaster Universities Arthritis Index, the 36-Item Short Form Health Survey, and overall satisfaction. From patient records, we recorded descriptive data, side (medial/lateral), previous or concurrent procedures, perioperative complications, revisions, and conversion to arthroplasty. Two-factor analysis of variance (ANOVA) was used to test for differences in age and body mass index (BMI). A 2 × 2 chi-square test was used to determine if the spectrum of procedures performed on our study’s patient group was representative of the entire population. PRO results were analyzed using a multivariate ANOVA.

Results:

From a total of 91 eligible patients, 61 (63 knees) met our inclusion criteria. Mean presurgery age was 25.5 ± 9.2 years, and mean BMI was 26.7 (range, 18.5-38.4). At follow-up (mean, 4.8 years; range, 1.0-13.6 years) overall PROs were statistically and clinically improved at final follow-up ( P ≤ .003); effect sizes were moderate and large. KOOS Pain and KOOS Activities of Daily Living showed some main or interaction effects that were trivial or small. Patient satisfaction with the treatment was ≥7 out of 10 in 85% of patients. A minimum of 1 subsequent surgery for various concerns was necessary in 23% of the 93 knees. Graft survival in the included patients was 100%.

Conclusion:

Complications (conditions requiring at least 1 subsequent surgery) affected about one-quarter of the patients who underwent MAT. Nevertheless, MAT seemed to provide our patients with adequate pain relief and improved function.

Biomaterials and Meniscal Lesions: Current Concepts and Future Perspective

Menisci are crucial structures for knee homeostasis. After a meniscal lesion, the golden rule, now, is to save as much meniscus as possible; only the meniscus tissue that is identified as unrepairable should be excised, and meniscal sutures find more and more indications. Several different methods have been proposed to improve meniscal healing. They include very basic techniques, such as needling, abrasion, trephination and gluing, or more complex methods, such as synovial flaps, meniscal wrapping or the application of fibrin clots. Basic research of meniscal substitutes has also become very active in the last decades. The aim of this literature review is to analyze possible therapeutic and surgical options that go beyond traditional meniscal surgery: from scaffolds, which are made of different kind of polymers, such as natural, synthetic or hydrogel components, to new technologies, such as 3-D printing construct or hybrid biomaterials made of scaffolds and specific cells. These recent advances show that there is great interest in the development of new materials for meniscal reconstruction and that, with the development of new biomaterials, there will be the possibility of better management of meniscal injuries

The Role of Collagen-Based Biomaterials in Chronic Wound Healing and Sports Medicine Applications

Advancements in tissue engineering have taken aim at treating tissue types that have difficulty healing naturally. In order to achieve improved healing conditions, the balance of exogenous matrix, cells, and different factors must be carefully controlled. This review seeks to explore the aspects of tissue engineering in specific tissue types treated in sports medicine and advanced wound management from the perspective of the matrix component. While the predominant material to be discussed is collagen I, it would be remiss not to mention its relation to the other contributing factors to tissue engineered healing. The main categories of materials summarized here are (1) reconstituted collagen scaffolds, (2) decellularized matrix tissue, and (3) non-decellularized tissue. These three groups are ordered by their increase in additional components beyond simply collagen.

Isolated high tibial osteotomy is appropriate in less than two-thirds of varus knees if excessive overcorrection of the medial proximal tibial angle should be avoided

PURPOSE

To perform a detailed deformity analysis of patients with varus alignment and to define the ideal osteotomy level (tibial vs. femoral vs. double level) to avoid an oblique joint line.

METHODS

A total of 303 digital full-leg standing radiographs of patients aged 18-60 years and varus alignment [mechanical tibiofemoral varus angle (mFTA) ≥ 3°] were included. All legs were analyzed regarding mFTA, mechanical medial proximal tibia angle (mMPTA), mechanical lateral distal femur angle (mLDFA), and joint line convergence angle. Based on mFTA, varus alignment was categorized as "mild" (3°-5°), "moderate" (6°-8°), or "severe" (≥ 9°). Deformity location was determined according to the malalignment test described by Paley. Two osteotomy simulations were performed with different upper limits for mMPTA: anatomic correction (mMPTA ≤ 90°, mLDFA ≥ 85°) and overcorrection (mMPTA ≤ 95°, mLDFA ≥ 85°). If a single osteotomy exceeded these limits at the intended mFTA of 2° valgus, a double-level osteotomy was simulated. If even a double-level osteotomy resulted in deviations from the defined limits, the leg was categorized as "uncorrectable".

RESULTS

Mean mFTA was 6° ± 11° of varus (range 3°-15°). A tibial deformity was observed in 28%, a femoral deformity in 23%, a combined tibial and femoral deformity in 4%, and no bony deformity in 45%. The prevalence of a tibial deformity did not differ between varus severity groups, whereas a femoral and bifocal deformity was significantly more prevalent in knees with more distinct varus (p < 0.001). Osteotomy simulation revealed that isolated high tibial osteotomy (HTO) was appropriate in only 12% for anatomic correction, whereas a double-level osteotomy was necessary in 63%. If overcorrection of mMPTA was tolerated, the number of HTOs significantly increased to 57% (p < 0.001), whereas the number of double-level osteotomies significantly decreased to 33% (p < 0.001). Isolated DFO was considered ideal in 8% for both simulations. Significantly more knees were considered "uncorrectable" by simulating anatomic correction (18 vs. 2%; p < 0.001). A double-level osteotomy was significantly more often necessary in knees with "severe" varus (p < 0.001).

CONCLUSION

Less than one-third of patients (28%) with mechanical varus ≥ 3° have a tibial deformity. If anatomic correction (mMPTA ≤ 90°) is intended, only 12% of patients can be corrected via isolated HTO, whereas 63% of patients require a double-level osteotomy. If slight overcorrection is accepted (mMPTA ≤ 95°), 57% of patients can be corrected via isolated HTO, whereas 33% of patients would still require a double-level osteotomy.

LEVEL OF EVIDENCE

III, cross-sectional study.

All-Arthroscopic Meniscal Allograft Transplantation Technique with Bone Plugs and Preloaded Sutures

The meniscus is an essential structure for the knee functioning and survival. Meniscectomy is the most common surgical procedure in orthopaedic surgery. Following total or subtotal meniscectomy, meniscal allograft transplantation (MAT) should be considered in symptomatic active young patients. Several MAT techniques have been described in the literature as an attempt to restore normal knee kinematics and potentially decrease the risk of developing knee osteoarthritis. The purpose of this article is to describe in detail an efficient and reproducible all-arthroscopic MAT technique with bone plugs and preloaded sutures.

Three-dimensional meniscus allograft sizing-a study of 280 healthy menisci

Background

Inaccurate meniscus allograft size is still an important problem of the currently used sizing methods. The purpose of this study was to evaluate a new three-dimensional (3D) meniscus-sizing method to increase the accuracy of the selected allografts.

Methods

3D triangular surface models were generated from 280 menisci based on 50 bilateral and 40 unilateral knee joint magnetic resonance imaging (MRI) scans. These models served as an imaginary meniscus allograft tissue bank. Meniscus sizing and allograft selection was simulated for all 50 bilateral knee joints by (1) the closest mean surface distance (MeSD) (3D-MRI sizing with contralateral meniscus), (2) the smallest meniscal width/length difference in MRI (2D-MRI sizing with contralateral meniscus), and (3) conventional radiography as proposed by Pollard (2D-radiograph (RX) sizing with ipsilateral tibia plateau). 3D shape and meniscal width, length, and height were compared between the original meniscus and the selected meniscus using the three sizing methods.

Results

Allograft selection by MeSD (3D MRI) was superior for all measurement parameters. In particular, the 3D shape was significantly improved (p < 0.001), while the mean differences in meniscal width, length, and height were only slightly better than the allograft selected by the other methods. Outliers were reduced by up to 55% (vs. 2D MRI) and 83% (vs. 2D RX) for the medial meniscus and 39% (vs. 2D MRI) and 56% (vs. 2D RX) for the lateral meniscus.

Conclusion

3D-MRI sizing by MeSD using the contralateral meniscus as a reconstruction template can significantly improve meniscus allograft selection. Sizing using conventional radiography should probably not be recommended.

Trial registration

Kantonale Ethikkommission Zürich had given the approval for the study (BASEC-No. 2018-00856).

Integration and Vascular Ingrowth of a Collagen Meniscal Implant: A Case Report

Meniscectomy is the most common surgery in orthopaedics. The absence of meniscal tissue might be related to irreversible damage to the articular cartilage. Meniscal replacement is a tissue-engineering technique for post-meniscectomy syndrome. Its success depends on the implant integration which was vastly proven in animal model studies. Histological evidence is hard to obtain in humans due to ethical issues. We report a clinical case in which a collagen scaffold meniscal implant was harvested six months after implantation due to mechanical failure. Histological analysis was performed revealing vascularisation not only of the peripheral attachment of the implant but also on the anterior horn. These morphologic findings demonstrate that this implant allows the colonisation by precursor cells and vessels, leading to the formation of a fully functional tissue. This present report is one of the few independent reports of scaffold biological integration in the literature.

Cells, soluble factors and matrix harmonically play the concert of allograft integration

Implantation of allograft tissues has massively grown over the last years, especially in the fields related to sports medicine. Beside the fact that often no autograft option exists, autograft related disadvantages as donor-site morbidity and prolonged operative time are drastically reduced with allograft tissues. Despite the well documented clinical success for bone allograft procedures, advances in tissue engineering raised the interest in meniscus, osteochondral and ligament/tendon allografts. Notably, their overall success rates are constantly higher than 80%, making them a valuable treatment option in orthopaedics, especially in knee surgery. Complications reported for allografting procedures are a small risk of disease transmission, immunologic rejection, and decreased biologic incorporation together with nonunion at the graft-host juncture and, rarely, massive allograft resorption. Although allografting is a successful procedure, improved techniques and biological knowledge to limit these pitfalls and maximize graft incorporation are needed. A basic understanding of the biologic processes that affect the donor-host interactions and eventual incorporation and remodelling of various allograft tissues is a fundamental prerequisite for their successful clinical use. Further, the importance of the interaction of immunologic factors with the biologic processes involved in allograft incorporation has yet to be fully dissected. Finally, new tissue engineering techniques and use of adjunctive growth factors, cell based and focused gene therapies may improve the quality and uniformity of clinical outcomes. The aim of this review is to shed light on the biology of meniscus, osteochondral and ligament/tendon allograft incorporation and how collection and storage techniques may affect graft stability and embodiment.Level of evidence V.

Autologous living chondrocytes contained in the meniscal matrix play an important role in in vivo meniscus regeneration induced by in situ meniscus fragment implantation

INTRODUCTION

Implantation of autogenous meniscal fragments wrapped with a fascia sheath significantly enhances fibrocartilage regeneration in vivo in defect cases at 12 weeks after implantation. The specific effects of the implanted autologous living chondrocytes and meniscal matrix have not been elucidated, however. The aim of this study was to clarify the role of autologous living chondrocytes contained in the meniscal matrix in in vivo meniscus regeneration induced by in situ meniscus fragment implantation.

HYPOTHESIS

Implantation of meniscus fragments containing autologous living chondrocytes may result in significant in vivo meniscus regeneration.

MATERIALS AND METHODS

Seventy-five rabbits were used in this study. A partial meniscectomy of the anterior one-third of the medial meniscus including the part of the anterior horn was performed. The rabbits were divided into 3 groups. In Group I, no treatment was applied to the defect. In Group II, the autogenous meniscal fragments devitalized by freeze-thaw treatment were reimplanted into the defect. In Group III, the autogenous meniscal fragments were reimplanted. In each group, the defect was covered with a fascia. Five rabbits from each group were subjected to morphologic and histologic evaluations at 3, 6, and 12 weeks, and 5 rabbits from each group were subjected to biomechanical evaluations at 6 and 12 weeks.

RESULTS

Histologically, no cells were seen in the grafted meniscal fragments at 3 weeks in Group II, whereas chondrocytes in the grafted meniscal fragments were alive at 3 weeks in Group III. Histologic and biomechanical data for Group II were slightly but significantly better than those of Group I at 12 weeks after implantation (p=0.007 and p=0.002, respectively), whereas the data for Group III were significantly superior to those of Groups I and II at 12 weeks (p<0.0014 and p<0.0029, respectively).

DISCUSSIONS

Grafted autologous living chondrocytes contained in the meniscal matrix play an important role in in vivo meniscus regeneration induced by in situ meniscus fragment implantation.

STUDY DESIGN

II, Controlled laboratory study.

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.

Preservation Methods Influence the Biomechanical Properties of Human Lateral Menisci: An Ex Vivo Comparative Study of 3 Methods

Background:

Three main meniscal preservation methods have been used over the past decade: cryopreservation, freezing, and freezing with gamma irradiation.

Hypothesis:

All 3 preservation methods will result in similar biomechanical properties as defined by tensile and compression testing.

Study Design:

Controlled laboratory study.

Methods:

A total of 24 human lateral menisci were collected from patients who underwent total knee arthroplasty. Inclusion criteria were patients younger than 70 years with primary unilateral (medial) femorotibial knee osteoarthritis. Each meniscus was divided into 2 specimens cross-sectionally. One specimen was systematically cryopreserved and constituted the control (Cy; –140°C), and the other specimen was used for either the simple frozen group (Fr; –80°C) or the frozen+irradiated group (FrI; –80°C + 25-kGy irradiation). Compression and tensile tests were performed to analyze the elasticity modulus (Young modulus) in compression, the elasticity modulus in tension, the tensile force at failure, and the rupture profile of the tensile stress-strain curve.

Results:

A significant difference in the mean compression elasticity modulus was observed between the Cy and Fr groups (28.86 ± 0.77 vs 37.26 ± 1.08 MPa, respectively; P < .001) and between the Cy and FrI groups (28.86 ± 0.77 vs 45.92 ± 1.09 MPa, respectively; P < .001). A significant difference in the mean tensile elasticity modulus was also observed between the Cy and Fr groups (11.66 ± 0.97 vs 19.97 ± 1.37 MPa, respectively; P = .008) and between the Cy and FrI groups (11.66 ± 0.97 vs 45.25 ± 1.39 MPa, respectively; P < .001). There were no significant differences between the control and study groups in tensile force at failure. The analysis of the stress-strain curve revealed a slow-slope curve with a nonabrupt rupture (ductile material) for the Cy samples versus a clear rupture of the curve for the Fr and FrI samples (more fragile material).

Conclusion:

Cryopreservation allows for more elastic and less fragile tissue compared with simple freezing or freezing plus irradiation.

Clinical Relevance:

The study results exhibit the detrimental effect of simple freezing and freezing plus irradiation on human meniscal mechanical properties. If these effects occur in menisci prepared for allograft procedures, important differences could appear in the graft’s mechanical behavior and thus patient outcomes.

Establishing Clinically Significant Outcomes After Meniscal Allograft Transplantation

Background:

Traditionally, the primary outcome in meniscal allograft transplantation (MAT) has been long-term survivorship; however, short-term clinically significant outcomes are necessary to fully evaluate patient improvement after surgery.

Purpose:

To (1) establish the minimal clinically important difference (MCID) and patient acceptable symptomatic state (PASS) with respect to patient-reported outcome measures (PROMs) and (2) evaluate preoperative and intraoperative variables correlated with achieving these threshold values.

Study Design:

Cohort study (diagnosis); Level of evidence, 2.

Methods:

A prospectively maintained institutional registry was queried for all MATs performed between 1999 and 2017. The following PROM scores were collected: International Knee Documentation Committee (IKDC) score, Lysholm score, and Knee injury and Osteoarthritis Outcome Score (KOOS). Patients who completed preoperative and postoperative PROMs within a 1-month window were included to calculate the distribution-based MCID at this interval. An anchor question regarding satisfaction with surgery was asked at the same time point and was employed to determine the PASS using nonparametric receiver operating characteristic curve/area under the curve analysis. Multivariate regression analysis was performed to correlate patient demographics, medical history, and concomitant procedures to propensity in achieving the MCID and PASS.

Results:

A total of 98 patients who underwent MAT met the inclusion/exclusion criteria, of whom 10 underwent concomitant ligamentous procedures, 65 underwent concomitant cartilage procedures, and 7 underwent concomitant realignment procedures. The mean patient age was 29.4 ± 9.0 years, and the mean body mass index (BMI) was 26.8 ± 5.2 kg/m². The distribution-based MCID and PASS were determined for the Lysholm score (12.3 and 66.5) and IKDC (9.9 and 36.0) as well as the KOOS Pain (9.9 and N/A ), Symptoms (9.7 and 73.0), Activities of Daily Living (9.5 and N/A), Sport (13.3 and N/A), and Quality of Life (14.6 and 53.0) subscales, respectively. A preoperative Short Form Physical Component Summary (SF PCS) score greater than 32.0 was predictive of postoperative satisfaction. Patients with work-related claims had a reduced likelihood of achieving the MCID for the IKDC and the PASS for the KOOS Symptoms. An increased BMI was also associated with failing to achieve the PASS for the KOOS Quality of Life (QOL).

Conclusion:

This study established the MCID and PASS for the Lysholm score, IKDC, and KOOS in patients undergoing MAT. Workers’ compensation and higher BMI were associated with failing to achieve clinically significant values. Lower preoperative Lysholm, IKDC, and KOOS scores were predictive of achieving the MCID, while higher preoperative SF PCS scores were associated with achieving satisfaction after MAT.

Meniscal allograft transplantation after meniscectomy: clinical effectiveness and cost-effectiveness

PURPOSE

To assess the clinical effectiveness and cost-effectiveness of meniscal allograft transplantation (MAT) after meniscal injury and subsequent meniscectomy.

METHODS

Systematic review of clinical effectiveness and cost-effectiveness analysis.

RESULTS

There is considerable evidence from observational studies, of improvement in symptoms after meniscal allograft transplantation, but we found only one small pilot trial with a randomised comparison with a control group that received non-surgical care. MAT has not yet been proven to be chondroprotective. Cost-effectiveness analysis is not possible due to a lack of data on the effectiveness of MAT compared to non-surgical care.

CONCLUSION

The benefits of MAT include symptomatic relief and restoration of at least some previous activities, which will be reflected in utility values and hence in quality-adjusted life years, and in the longer term, prevention or delay of osteoarthritis, and avoidance or postponement of some knee replacements, with resulting savings. It is likely to be cost-effective, but this cannot be proven on the basis of present evidence.

LEVEL OF EVIDENCE

IV.

An original all-arthroscopic technique for bony fixation of lateral meniscus allograft via four tibial tunnels: A cadaver study

Bone fixation of the two roots improves meniscal allograft positioning as compared to simple meniscal peripheral wall fixation. An all-arthroscopic 4-point bone fixation technique could provide rigid primary fixation and a more stable allograft. The technique was implemented on 8 fresh cadavers, under arthroscopy, via tibial bone tunnels at the posterior root, popliteal hiatus, anteromedial segment and anterior root, with cortical buttons for tibial graft fixation. Mean surgery time was 65±5minutes (range, 55-80min). The main difficulty lay in creating the tunnel to fix the anterior horn, which sometimes required an additional lateral portal. This 4-point bone fixation technique proved feasible and reproducible, and offers a novel means of stable primary fixation. LEVEL OF EVIDENCE: IV, cadaver study.

Medial meniscus extrusion increases with age and BMI and is depending on different loading conditions

PURPOSE

Meniscus extrusion has always been described as an indirect sign of meniscus pathology and is associated with a loss of function of the affected meniscus. The current cut-off value of 3 mm displacement is indicated as abnormal and has been determined on magnetic resonance images (MRI) and ultrasound (US). However, it has to be considered that there is no description of the physiological meniscus extrusion in healthy knees depending on age or different weight-bearing conditions. It was hypothesized that in healthy knees there is a physiological age and BMI dependent meniscal extrusion, and meniscus extrusion depends on different loading conditions.

METHODS

Healthy volunteers with non-symptomatic knee, and no history of knee injuries or operations were included in this prospective cross-sectional study. Exclusion criteria were age < 18years, subjective or objective instability, malalignment and positive medial meniscus test. Secondary exclusion criteria were osteoarthritis ICRS grade 3-4 or signs of meniscus tear on MRI. Every patient underwent standard knee examination following measurement of medial meniscus extrusion (MME) using US. In US extrusion was determined in supine position (unloaded) and in standing position with full weight-bearing and 20° of flexion (loaded). MRI was performed in a neutral knee position to compare ultrasound measurements with the current gold standard. Based on the power calculation of preliminary results a minimum of 70 volunteers was needed.

RESULTS

75 patients were enrolled to this study. The mean US MME was 1.1 mm ± 0.5 mm in supine position and 1.9 mm ± 0.9 mm under full weight-bearing. The mean US Δ-extrusion was 0.8 mm ± 0.6 mm. With rising age, a significant increased MME in US and MRI could be demonstrated (p < 0.001). Furthermore, elevated BMI was significantly correlated to increased US MME under full weight-bearing (p = 0.002) and to US Δ-extrusion (p = 0.003).

CONCLUSION

Based on the results of this study, medial meniscus extrusion is an age-depending phenomenon in healthy knees and depends on various load-bearing conditions. Ultrasound examination of the MME might be favorable compared to MRI due to the ability of dynamic evaluation. As a consequence, the current cut-off value of 3 mm for meniscus pathologies should be reconsidered.

LEVEL OF EVIDENCE

III.

Biomechanical, structural and biological characterisation of a new silk fibroin scaffold for meniscal repair

Meniscal injury is typically treated surgically via partial meniscectomy, which has been shown to cause cartilage degeneration in the long-term. Consequently, research has focused on meniscal prevention and replacement. However, none of the materials or implants developed for meniscal replacement have yet achieved widespread acceptance or demonstrated conclusive chondroprotective efficacy.

A redesigned silk fibroin scaffold, which already displayed promising results regarding biocompatibility and cartilage protection in a previous study, was characterised in terms of its biomechanical, structural and biological functionality to serve as a potential material for permanent partial meniscal replacement. Therefore, different quasi-static but also dynamic compression tests were performed. However, the determined compressive stiffness (0.56 ± 0.31 MPa and 0.30 ± 0.12 MPa in relaxation and creep configuration, respectively) was higher in comparison to the native meniscal tissue, which could potentially disturb permanent integration into the host tissue. Nevertheless, µ-CT analysis met the postulated requirements for partial meniscal replacement materials in terms of the microstructural parameters, like mean pore size (215.6 ± 10.9 µm) and total porosity (80.1 ± 4.3%). Additionally, the biocompatibility was reconfirmed during cell culture experiments. The current study provides comprehensive mechanical and biological data for the characterisation of this potential replacement material. Although some further optimisation of the silk fibroin scaffold may be advantageous, the silk fibroin scaffold showed sufficient biomechanical competence to support loads already in the early postoperative phase.

Comparative Matched-Pair Analysis of Keyhole Bone-Plug Technique Versus Arthroscopic-Assisted Pullout Suture Technique for Lateral Meniscal Allograft Transplantation

PURPOSE

To compare the clinical outcomes and meniscal extrusion measured by magnetic resonance imaging (MRI) between the keyhole bone-plug technique and arthroscopic-assisted pullout suture technique in lateral meniscal allograft transplantation (MAT).

METHODS

Between October 2009 and February 2015, patients who underwent lateral MAT were retrospectively reviewed. The inclusion criteria were patients with symptomatic knees that had undergone total or subtotal meniscectomy who were treated with lateral MAT with a minimum follow-up period of 2 years. We excluded 13 patients with anterior cruciate ligament injury to the ipsilateral knee and 6 patients with combined cartilage procedures. In addition, we excluded 19 patients because they did not undergo follow-up MRI and 13 patients who did not undergo more than 2 years of follow-up. Thirty-seven patients who underwent lateral MAT with the keyhole bone-plug technique were identified and assigned to group A. Forty-five patients who underwent lateral MAT with the arthroscopic-assisted pullout suture technique (group B) were then matched by age, body mass index, and time from previous meniscectomy to lateral MAT. Clinical outcome assessments included preoperative and postoperative subjective International Knee Documentation Committee (IKDC), Tegner, and Lysholm scores and the visual analog scale (VAS) score for pain evaluation. MRI was used to assess meniscal extrusion.

RESULTS

The mean follow-up period was 35.8 ± 6.5 months (range, 24-65 months) in group A and 34.6 ± 6.2 months (range, 24-55 months) in group B. Significant improvements in the VAS pain score, subjective IKDC score, Tegner score, and Lysholm score after lateral MAT were found (P < .001), and there were no significant differences between the 2 groups at final follow-up (VAS score, 1.4 ± 0.8 in group A and 1.2 ± 1.0 in group B [P = .164]; subjective IKDC score, 72.9 ± 8.1 in group A and 74.2 ± 7.3 in group B [P = .427]; Tegner activity score, 4.0 ± 0.9 in group A and 4.1 ± 0.8 in group B [P = .374]; and Lysholm score, 75.5 ± 10.6 in group A and 76.2 ± 11.8 in group B [P = .786]). On MRI, the meniscal extrusion extent was 3.1 ± 0.9 mm in group A and 2.9 ± 0.8 mm in group B (P = .223), and the relative percentages of extrusion were 27.0% ± 3.9% and 26.1% ± 4.2%, respectively (P = .273).

CONCLUSIONS

Compared with the keyhole bone-plug technique, the arthroscopic-assisted pullout suture technique in lateral MAT showed comparable clinical and MRI results at short-term follow-up.

LEVEL OF EVIDENCE

Level IV, case series with intragroup comparisons.

Meniscal Allograft Transplantation: The Effect of Cartilage Status on Survivorship and Clinical Outcome

PURPOSE

To evaluate the survivorship of meniscal allograft transplantations (MATs), their clinical outcomes, and to compare the effect of perioperative cartilage status on survivorship.

METHOD

A consecutive series of MATs with a minimum postsurgical time of 4 years were included from a prospectively collected database from 2001 to 2015. Mechanical failure was defined as transplant removal or knee arthroplasty. The effect of peri-operative cartilage status on survivorship was analyzed using a Kaplan-Meier analysis. Also, pre- and postoperative outcome scores were evaluated. The clinical outcome tools used were the Lysholm Knee Scoring Scale, Tegner Activity Level Scale, Oxford Knee Score (OKS) and International Knee Documentation Committee (IKDC) subjective knee form.

RESULTS

The mean (±SD) postsurgical follow-up (n = 45 MATs, 43 knees) was 8.6 ± 3.4 years. Among the 45 MATs, 31 had an Outerbridge Cartilage Score (OCS) of 3 to 4. Eight transplants (17.7%) failed at an average of 6.1 ± 4.4 years postoperatively, and all occurred in patients with an OCS of 3 to 4. Functional outcomes showed significant improvement in the Lysholm by 17.7 points (95% confidence interval [CI], 8.5-26.9, P < .001), OKS by 8 (CI, 0.81-15.11, P = .031), and IKDC scores by 15.6 (CI, 6-25.2, P = .001). However, the Tegner score improvement by 0.6 was not statistically significant (CI, 0.3545-1.6212, P = .2). In a subanalysis, the OCS 3-4 group had a significant improvement in all the clinical outcomes except the Tegner score. In the OCS 0-2 group, the Lysholm and Tegner significantly improved, whereas the improvement in the OKS and IKDC was not significant.

CONCLUSIONS

MAT is a viable and effective surgical option for the painful meniscus-deficient knee, with good survivorship and functional outcomes in the medium to long term. Mechanical failure is associated with advanced OCS. Patients with minimal cartilage damage have improved MAT survivorship but both groups benefit clinically.

LEVEL OF EVIDENCE

Level IV, case series.

Capsulodesis Versus Bone Trough Technique in Lateral Meniscal Allograft Transplantation: Graft Extrusion and Functional Results

PURPOSE

To compare the radiographic results (in terms of graft extrusion) and the functional results of lateral meniscus allograft transplantations (MAT) performed with a bony fixation technique or with a soft tissue fixation technique after capsulodesis.

METHODS

A prospective series of 29 consecutive lateral MAT was analyzed. The inclusion criterion for MAT was lateral joint line pain due to a previous meniscectomy. Malalignment, patients who had an Ahlback grade greater than II, and patients with a body mass index over 30 were considered as the exclusion criterion to prevent confounding results. Fifteen of the grafts were fixed with a bony fixation technique (group A). The remaining 14 cases (group B) were fixed with sutures through bone tunnels after lateral capsular fixation (capsulodesis). All patients were studied with magnetic resonance imaging to determine the degree of meniscal extrusion at an average of 18 months of surgery (range, 12-48 months). Meniscal extrusion was measured on coronal magnetic resonance imaging. To standardize the results, the percentage of meniscus extruded for each group was also calculated and compared. The functional results were analyzed by means of standard knee scores (Lysholm, Tegner, and visual analog scale).

RESULTS

If we consider the first 4 cases of group B as the learning curve of the new technique, we observe that group A had 8 cases (53.3%) of major extrusion, whereas group B had 1 case (7.1%) (P = .02). When comparing the degree of meniscal extrusion with the type of fixation employed, an even lower percentage of extruded menisci was found in group B (P = .01). The final follow-up Lysholm score in group A was 94.33 ± 5.96 (P < .001) and 91.43 ± 6.19 (P < .001) in group B. The median follow-up Tegner score significantly improved from 4 (range, 2-5) to 7 (range, 6-9) in group A (P < .001) and from 4 (range, 3-5) to 7 (range, 6-8) in group B (P < .001). The average visual analog scale score dropped down 5.87 and 7.29 points in groups A and B, respectively (P < .001). The Knee Injury and Osteoarthritis Outcome Score improved from 51.98 ± 2.84 to 90.88 ± 7.53 in group A (P < .001) and from 50.44 ± 2.32 to 92.01 ± 6.71 in group B (P < .001). Patient satisfaction with regard to the procedure stood at a mean of 3.6 ± 0.2 points out of a maximum of 4 in group A and 3.8 ± 0.4 in group B. There were no complications in this series.

CONCLUSIONS

The capsulodesis technique in lateral MAT proved not to be statistically different at decreasing the degree of meniscal extrusion with respect to the bone-bridge fixation. If the first 4 cases using the new capsulodesis technique had not included in the results, the capsulodesis technique would have effectively presented better results relative to the degree of meniscal extrusion compared with the bone-bridge fixation technique. In addition, the functional results were similar.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

The Influence of Full-Thickness Chondral Defects on Outcomes Following Meniscal Allograft Transplantation: A Comparative Study

PURPOSE

To compare a series of patients who underwent meniscus allograft transplantation (MAT) with full-thickness chondral defects (FTD) with those with no chondral defect (ND) with regard to the following: change in patient-reported outcomes (PROs) from baseline to 2-year follow-up and baseline to the final follow-up (including comparisons to minimal clinically important differences), complications and complication rates, reoperations and reoperation rates/timing, and failures and time to failure (revision MAT or conversion to total knee arthroplasty).

METHODS

Patients who underwent isolated medial or lateral MAT between September 1997 and March 2013 with a minimum of 2 years of follow-up were retrospectively identified and split into 2 groups based on the presence or absence of FTD (femoral condyle or tibial plateau) identified intraoperatively after debridement to allow for a better understanding of the lesion characteristics (when applicable): ND (Outerbridge grade 0/I) or FTD (Outerbridge grade IV). Patients with osteochondritis dissecans were eligible for inclusion, as were those with isolated single lesions, multiple lesions, or bipolar lesions. Those with a moderate Outerbridge grade (II and III)-whether treated or neglected-were excluded given the poorer reliability of grading intermediate lesions. Indications for MAT included those patients with subjective complaints (persistent joint-line pain) and objective findings (previous meniscectomy or nonviable meniscus state with pain localized to the affected compartment) of functional meniscal deficiency. All lateral MAT patients used a bridge-in-slot surgical technique, as did most medial MAT patients (few patients with earlier surgical dates received a keyhole technique). All FTD were treated concurrently at the time of index MAT with cartilage restoration procedures (microfracture, autologous chondrocyte implantation, DeNovo particulate cartilage grafting, or osteochondral auto/allografting). Reoperations, failures (revision MAT or conversion to arthroplasty), and PRO deltas were reported comparing baseline to 2-year follow-up and baseline to the final follow-up. Intergroup comparisons were made using Bonferroni-adjusted independent sample t-tests for continuous variables and χ-square for categorical variables.

RESULTS

A total of 91 patients (22 ND and 69 FTD) were identified and followed for a mean 4.48 ± 2.63 and 3.84 ± 2.47 years, respectively. There were no significant between-group differences in age, body mass index, or number of prior surgeries. The mean chondral lesion size in the FTD group was 4.43 ± 2.5 cm². Concomitant anterior cruciate ligament reconstruction was performed significantly more in ND-group patients than FTD-group patients (8 [38.1%] vs 8 [11.8%], P = .004). There were no differences between ND-group and FTD-group patients in concomitant realignment procedures performed (2 [9.1%] vs 7 [10.1%], P = .986), or prior ligament reconstruction (9 [40.9%] vs 18 [26.1%], P = .111) or realignment procedure (0 [0%] vs 0 [0%]). FTD-group patients underwent concomitant osteochondral allograft (69.6%), autologous chondrocyte implantation (18.8%), microfracture (13.0%), osteochondral autograft (4.3%), or DeNovo juvenile particulate cartilage implantation (1.4%). A comparison of the patient groups found no statistically significant differences in PROs preoperatively (P > .003 for all). Intergroup comparisons of both the 2-year and final follow-up delta PRO scores showed no statistically (P > .003 for all) or clinically (number of PROs meeting minimal clinically important differences) significant differences. One complication occurred (fractured hardware) in the FTD-group patients (1.3%). There were no differences in the number of subsequent surgeries (revision MAT: ND, 2 (10.0%) vs FTD, 8 (12.9%); P = .845) or failures (conversion to total knee arthroplasty: ND, 1 (5.0%) vs FTD, 2 (3.3%); P = .646).

CONCLUSIONS

When comparing a patient series with FTD who underwent MAT with a patient series with ND, there were no differences in the change in individual PROs from preoperative to the final follow-up. Similarly, there were no differences in complications or failure between those with ND or FTD diagnosed intraoperatively. The results of the current study suggest that chondral damage identified and treated by cartilage restoration means at the time of MAT may not affect the clinical outcomes of MAT.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Mechanical viability of a thermoplastic elastomer hydrogel as a soft tissue replacement material

Hydrogels are a class of synthetic biomaterials composed of a polymer network that swells with water and as such they have both an elastic and viscous component making them ideal for soft tissue applications. This study characterizes the compressive, tensile, and shear properties of a thermoplastic elastomer (TPE) hydrogel and compares the results to published literature values for soft tissues such as articular cartilage, the knee meniscus, and intervertebral disc components. The results show the TPE hydrogel material is viscoelastic, strain rate dependent, has similar surface and bulk properties, displays minimal damping under dynamic load, and has tension-compression asymmetry. When compared to other soft tissues it has a comparable equilibrium compressive modulus of approximately 0.5MPa and shear modulus of 0.2MPa. With a tensile modulus of only 0.2MPa though, the TPE hydrogel is inferior in tension to most collagen based soft tissues. Additional steps may be necessary to reinforce the hydrogel system and increase tensile modulus depending on the desired soft tissue application. It can be concluded that this material could be a viable option for soft tissue replacements.

Bone Trough Lateral Meniscal Allograft Transplantation: The Tapered Teardrop Technique

The meniscus plays a vital role in knee biomechanics, and its physical absence or functional incompetence (e.g., irreparable root or radial tear) leads to unacceptably high rates of joint degeneration in affected populations. Meniscal allograft transplantation has been used successfully to treat patients with postmeniscectomy syndrome, and there is early laboratory and radiographic evidence hinting at a potential prophylactic role in preventing joint degeneration. We present a technique for lateral meniscal allograft transplantation using the CONMED Meniscal Allograft Transplantation system.

Current advances in the development of natural meniscus scaffolds: innovative approaches to decellularization and recellularization

The increasing rate of injuries to the meniscus indicates the urgent need to develop effective repair strategies. Irreparably damaged menisci can be replaced and meniscus allografts represent the treatment of choice; however, they have several limitations, including availability and compatibility. Another approach is the use of artificial implants but their chondroprotective activities are still not proved clinically. In this situation, tissue engineering offers alternative natural decellularized extracellular matrix (ECM) scaffolds, which have shown biomechanical properties comparable to those of native menisci and are characterized by low immunogenicity and promising regenerative potential. In this article, we present an overview of meniscus decellularization methods and discuss their relative merits. In addition, we comparatively evaluate cell types used to repopulate decellularized scaffolds and analyze the biocompatibility of the existing experimental models. At present, acellular ECM hydrogels, as well as slices and powders, have been explored, which seems to be promising for partial meniscus regeneration. However, their inferior biomechanical properties (compressive and tensile stiffness) compared to natural menisci should be improved. Although an optimal decellularized meniscus scaffold still needs to be developed and thoroughly validated for its regenerative potential in vivo, we believe that decellularized ECM scaffolds are the future biomaterials for successful structural and functional replacement of menisci.

Comparison of medial versus lateral meniscus allograft transplantation. Literature review and meta-analysis

Objectives:

To perform a literature review and meta-analysis evaluating the effectiveness of medial and lateral meniscus allograft transplantation (MAT).

Methods:

The literature review and meta-analysis were conducted between August and October 2015 in the People’s Hospital of China Three Gorges University, Yi Chang, China. A systematic search was performed in the Medline and EMBASE databases, and the Cochrane Library for relevant literature published through October 2015. The outcomes of the included studies were analyzed in terms of the Lysholm Score, International Knee Documentation Committee (IKDC) Score, Knee Injury And Osteoarthritis Outcome Score (KOOS), Visual Analog Scale (VAS), Tegner Activity Score, MRI results, and failure rates. An adapted version of the Newcastle-Ottawa Scale was used for the methodological quality assessment in the meta-analyses.

Results:

The literature review identified 12 observational studies, including 7 retrospective studies, 4 prospective studies, and the nature of one study was not reported. Significant differences in the outcomes of the lateral MAT group and the medial MAT group were observed in the IKDC scores, KOOS pain values, KOOS activities of daily living (ADL) values, and the absolute and relative extrusions observed on MRI, which suggested that the lateral MAT patients experienced superior clinical benefits compared with the medial MAT patients. However, significant differences between the lateral MAT group and the medial MAT group were not observed with regards to the Lysholm Scores, KOOS symptom values, KOOS sports and recreations values, KOOS quality of life (QOL) values, Tegner Activity Scores, VAS for pain values, and failure rates.

Conclusion:

The analysis results indicated that lateral MAT provides superior clinical outcomes compared with medial MAT according to the KOOS and IKDC scores. In addition, greater graft extrusion was observed in the medial group on MRI. Although significant differences were not detected between the 2 groups, the medial MAT patients were more prone to failure compared with the lateral MAT patients.

Lateral Meniscus Allograft Transplantation: The Bone Plug Technique

Lateral meniscus tears are commonly encountered by orthopaedic surgeons. Despite efforts to repair and preserve the meniscus, meniscectomy is occasionally required to treat irreparable tears. The resulting lateral meniscus deficiency leads to increased tibiofemoral contact pressures and ultimately early osteoarthritic changes in the knee. Lateral meniscal allograft transplant (LMAT) has been proposed as a way to restore the lateral meniscus-deficient knee to its native form. Although several techniques for LMAT have been proposed, osseous fixation has demonstrated increased stability, improved outcomes, and improved long-term survival. This article presents a technique for LMAT using bone plugs and standard arthroscopic portals.

Meniscal transplantation: procedures, outcomes, and rehabilitation

Meniscal allograft transplantation (MAT) is a possible treatment option for patients with joint pain after meniscectomy. It is necessary that the joint be aligned and stable. Current evidence shows that MAT improves pain and mechanical function in the mid to long term with patients reporting significantly improved outcomes at up to 15 years following surgery. Studies on survivorship showed up to 76% graft survival at 10 years. Recent studies have suggested a chondroprotective effect, but there is, at present, no evidence to support MAT in the prevention of osteoarthritis. This review article reported the current evidence for MAT showing support for fresh frozen, nonirradiated allografts. However, further research is required to determine the ideal indications for MAT, the optimal graft fixation method, and the safest rehabilitation protocol.

Meniscal allograft transplantation: a meta-analysis

PURPOSE

This meta-analysis evaluates the mid- to long-term survival outcome of MAT (meniscal allograft transplantation). Potential prognosticators, with particular focus on chondral status and age of the patient at the time of transplantation, were also analysed.

STUDY DESIGN

Meta-analysis.

METHODS

An online database search was performed using following search string: "meniscal allograft transplantation" and "outcome". A total of 65 articles were analysed for a total of 3157 performed MAT with a mean follow-up of 5.4 years. Subjective and clinical data was analysed.

RESULTS

The subjective and objective results of 2977 patients (3157 allografts) were analysed; 70% were male, 30% were female. Thirty-eight percent received an isolated MAT. All other patients underwent at least one concomitant procedure. Lysholm, Knee injury and Osteoarthritis Outcome (KOOS), International Knee Documentation Committee (IKDC) and Visual Analogue Scale (VAS) scores were analysed. All scores showed a good patient satisfaction at long-term follow-up. The mean overall survival rate was 80.9%. Complication rates were comparable to standard meniscal repair surgery. There was a degenerative evolution in osteoarthritis with at least one grade in 1760 radiographically analysed patients. Concomitant procedures seem to have no effect on the outcome. Age at transplantation is a negative prognosticator. The body mass index (BMI) of the patient shows a slightly negative correlation with the outcome of MAT.

CONCLUSIONS

MAT is a viable solution for the younger patient with chronic pain in the meniscectomised knee joint. The complications are not severe and comparable to meniscal repair. The overall failure rate at final follow-up is acceptable and the allograft heals well in most cases, but MAT cannot be seen as a definitive solution for post-meniscectomy pain. The correct approach to the chronic painful total meniscectomised knee joint thus requires consideration of all pathologies including alignment, stability, meniscal abnormality and cartilage degeneration. It requires possibly combined but appropriate action in that order.