Lateral Capsular Stabilization in Lateral Meniscal Allograft Transplantation

Background: Stabilization of the lateral capsule to the tibial plateau may decrease midbody extrusion after lateral meniscal allograft transplantation (MAT). However, there is a paucity of literature reporting on postoperative magnetic resonance imaging (MRI) findings after lateral capsular stabilization (LCS) at the time of lateral MAT. Purpose/Hypothesis: The purpose was to describe MRI findings after LCS and compare postoperative extrusion between isolated lateral MAT and lateral MAT with LCS. It was hypothesized that allograft extrusion would be reduced after MAT with LCS but that the stabilized capsule would increase the risk of tears to the capsule or allograft. Study Design: Cohort study; Level of evidence, 3. Methods: Included were patients who underwent lateral MAT with 6-month follow-up MRI. Concomitant LCS was performed for patients with redundant lateral capsule displaced from the lateral tibial plateau as evident on coronal MRI or arthroscopic examination (MAT+LCS group); otherwise, patients underwent MAT only (isolated MAT group). The Lysholm score, Tegner score, and lateral joint space on radiographs were compared between the 2 groups at 2 years postoperatively, and the stabilized lateral capsule and allograft were evaluated using 6-month follow-up MRI. Extrusion, rotation, and position of the allograft bridge were compared between the 2 groups. Regression analysis was performed to identify factors predictive of degree of extrusion. Results: There were 10 patients in the MAT+LCS group and 13 patients in the isolated MAT group. No significant differences were found between groups in preoperative patient characteristics or postoperative Lysholm score, Tegner score, lateral joint space, or MRI parameters. Postoperative extrusion was not related to obliquity angle, position of the bony bridge, or presence of LCS. In the MAT+LCS group, 1 patient showed a tear of the lateral capsule and a radial tear of the allograft, and 3 patients had a meniscocapsular separation at the midbody of the allograft. In the isolated MAT group, 1 patient had a peripheral tear at the midbody, but there was no tear of the allograft in the other patients. Conclusion: LCS did not decrease extrusion of lateral meniscal transplantation, but it can lead to increased risk for graft or capsule tear.

Clinical Outcomes of Meniscal Allograft Transplantation With Respect to the Minimal Clinically Important Difference

Background: Arthroscopic-assisted meniscal allograft transplantation (MAT) has become a viable and effective treatment option for young active patients with postmeniscectomy pain. The minimal clinically important difference (MCID) of patient-reported outcome measures (PROMs) is imperative to evaluate the clinical significance of surgical interventions and inform clinical practice guidelines in orthopaedic surgery. Purpose: To perform a systematic review of clinical outcome studies of patients undergoing MAT and compare postoperative improvement with established MCID thresholds. Study Design: Systematic review and meta-analysis; Level of evidence, 4. Methods: A systematic review was performed using the PubMed, Web of Science, and Cochrane Library databases. A meta-analysis was performed using data obtained from studies reporting patient-reported outcomes. Subgroup analysis was performed on patients undergoing isolated lateral MAT using fresh-frozen grafts. Weighted mean postoperative improvements in the International Knee Documentation Committee (IKDC), Lysholm, and visual analog scale for pain (VAS pain) were calculated and compared with MCID values to determine if they met the MCID threshold. Results: A total of 35 studies were identified, including 1658 unique patients. Weighted mean postoperative score improvements exceeded MCID thresholds for the VAS pain, IKDC, and Lysholm. Subgroup analysis of patients undergoing isolated lateral fresh-frozen MAT demonstrated postoperative improvements exceeding the MCID for the Lysholm and VAS pain. Conclusion: Evaluating postoperative PROMs with respect to the MCID is crucial to evaluate the effect of MAT on functional improvement. The results of the present meta-analysis suggest that postoperative improvements after MAT are clinically meaningful as reflected by PROMs exceeding the MCID threshold for the IKDC, Lysholm, and VAS pain.

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

Background: Meniscal deficiency has been reported to increase contact pressures in the affected tibiofemoral joint, possibly leading to degenerative changes. Current surgical options include meniscal allograft transplantation and insertion of segmental meniscal scaffolds. Little is known about segmental meniscal allograft transplantation. Purpose: To evaluate the effectiveness of segmental medial meniscal allograft transplantation in the setting of partial medial meniscectomy in restoring native knee loading characteristics. Study Design: Controlled laboratory study. Methods: Ten fresh-frozen human cadaveric knees underwent central midbody medial meniscectomy and subsequent segmental medial meniscal allograft transplantation. Knees were loaded in a dynamic tensile testing machine to 1000 N for 20 seconds at 0°, 30°, 60°, and 90° of flexion. Four conditions were tested: (1) intact medial meniscus, (2) deficient medial meniscus, (3) segmental medial meniscal transplant fixed with 7 meniscocapsular sutures, and (4) segmental medial meniscal transplant fixed with 7 meniscocapsular sutures and 1 suture fixed through 2 bone tunnels. Submeniscal medial and lateral pressure-mapping sensors assessed mean contact pressure, peak contact pressure, mean contact area, and pressure mapping. Two-factor random-intercepts linear mixed effects models compared pressure and contact area measurements among experimental conditions. Results: The meniscal-deficient state demonstrated a significantly higher mean contact pressure than all other testing conditions (mean difference, ≥0.35 MPa; P < .001 for all comparisons) and a significantly smaller total contact area as compared with all other testing conditions (mean difference, ≤140 mm2; P < .001 for all comparisons). There were no significant differences in mean contact pressure or total contact area among the intact, transplant, or transplant-with-tunnel groups or in any outcome measure across all comparisons in the lateral compartment. No significant differences existed in center of pressure and relative pressure distribution across testing conditions. Conclusion: Segmental medial meniscal allograft transplantation restored the medial compartment mean contact pressure and mean contact area to values measured in the intact medial compartment. Clinical Relevance: Segmental medial meniscal transplantation may provide an alternative to full meniscal transplantation by addressing only the deficient portion of the meniscus with transplanted tissue. Additional work is required to validate long-term fixation strength and biologic integration.

Epidemiology of Meniscal Allograft Transplantation at Children’s Hospitals in the United States

Background: Meniscal allograft transplantation (MAT) was developed with the goal of delaying the progression of degenerative disease in the setting of substantial meniscal deficiency. This may be especially important in children and adolescents; however, there is a paucity of literature on MAT in this population. Purpose: To evaluate the epidemiology of MAT at pediatric hospitals in the United States, with specific attention to regional and characteristic trends. Study Design: Case-control study; Level of evidence, 3. Methods: The Pediatric Health Information System, a national database consisting of 49 children’s hospitals, was queried for all patients younger than 25 years who underwent MAT between 2011 and 2018. Characteristic information and surgical history were collected for each patient. The database was also queried for all patients who underwent other meniscal surgeries (including debridement, meniscectomy, and meniscal repair) during the same period (controls). Characteristic and geographic data from the control group were compared with those of the patients who underwent MAT. Univariate analysis was followed by purposeful entry multivariate regression to adjust for confounding factors. Results: A total of 27,168 meniscal surgeries were performed in 47 hospitals, with MAT performed 67 times in 17 hospitals. Twelve (18%) patients underwent a subsequent procedure after transplantation. In multivariate analysis, each year of increasing age resulted in 1.1 times higher odds of having undergone MAT (95% CI, 1.03-1.1; P = .002) compared with repair or meniscectomy. Patients who underwent MAT also had 2.0 times higher odds of being women (95% CI, 1.2-3.3; P = .01) and 2.0 times higher odds of being privately insured (95% CI, 1.1-3.6; P = .02). MAT was performed most frequently in the Northeast (4.9/1000 meniscal surgeries) and least often in the South (1.1/1000 meniscal surgeries) ( P < .001). Conclusion: In the United States, pediatric and adolescent patients who underwent MAT were older and more likely to be female and have private insurance than those undergoing meniscal repair or meniscectomy. MAT was only performed in 17 of 47 children’s hospitals that perform meniscal surgery. These trends highlight the need for further research, especially regarding differences along the lines of sex and insurance status.