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

Serial Changes in Muscle Strength and Dynamic Balance After Lateral Meniscal Allograft Transplantation: A Retrospective Cohort Study of 55 Patients

BACKGROUND

Despite numerous studies examining subjective clinical scores after meniscal allograft transplantation (MAT), research focusing specifically on functional measures is lacking.

PURPOSE

To evaluate the serial changes in isokinetic muscle strength and dynamic balance during the first postoperative year after lateral MAT (LMAT).

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 55 patients who underwent LMAT underwent subjective functional assessment using the Lysholm and subjective International Knee Documentation Committee (IKDC) scores. The objective functions, evaluated using isokinetic muscle strength testing and the Y-balance test for dynamic postural stability, were recorded preoperatively and 6 and 12 months postoperatively. Magnetic resonance imaging (MRI) was performed at 2 days and 12 months postoperatively to evaluate the meniscal allograft extrusion and cartilage condition in the lateral compartment. At 12 months, patients with graft extrusion >3 mm on MRI were assigned to the extrusion group.

RESULTS

Significant improvements were observed in the Lysholm and subjective IKDC scores at 12 months postoperatively (both P < .001). The joint space width did not significantly increase (P = .054). Coronal graft extrusion increased significantly (P < .001). At 6 months postoperatively, isokinetic muscle strength tests indicated no significant reduction in the peak torque for knee extension (P = .911). However, at 12 months, the peak torque was significantly increased (P = .001), with the deficits improving from 38.3% to 18.1% (P < .001). No significant changes were noted in the knee flexion strength. Dynamic postural stability showed a significant decrease in the Limb Symmetry Index (LSI) for the anterior reach at 6 months (P = .004), but significant improvements were seen by 12 months, with the LSI values for the anterior, posteromedial, and posterolateral reaches all exceeding 90% (P < .001). No significant differences in muscle strength or dynamic balance were found between the nonextrusion (n = 41) and extrusion (n = 14) groups at 12 months.

CONCLUSION

The significant improvements in isokinetic muscle strength and dynamic postural stability achieved only by 12 months after LMAT underscores the necessity of a comprehensive rehabilitation program and caution against premature sports resumption.

Meniscal extrusion: Proposal for a novel qualitative classification

Meniscal extrusion (ME), defined as the radial displacement of the meniscal body outside the margins of the tibial plateau, has been seen as an independent and relevant predictor of intra-articular knee degeneration. Nonetheless, available classifications for ME are exclusively quantitative assessments not considering the context in which extrusion is identified. Indeed, ME can be the result of several different conditions spanning from acute tears to chronic degeneration and its definition cannot be only dependent on the numeric calculation of the radial displacement of the meniscal body. Furthermore, growing evidence supports the existence of a paraphysiological ME resulting from joint loading, limb malalignment, anatomical abnormalities of the meniscal attachments to the femur and tibia or a nonpathological finding after meniscal allograft transplantation. It is therefore clear that an exclusively quantitative assessment of ME cannot be sufficient since this condition can develop in such different clinical scenarios. For this reason, a novel qualitative classification for ME is proposed, differentiating between three distinct conditions: a paraphysiological ME, a pathological ME and ME related to degenerative conditions. Furthermore, a comprehensive review of the present literature has been conducted to report the most relevant and updated evidence on the topic highlighting the difference in the clinical management of each different category.

Level of Evidence

Not applicable.

Editorial Commentary: Meniscal Allograft Transplantation Results in Both Pain Relief and Chondroprotection

Meniscal allograft transplantation (MAT) effectively alleviates symptoms of the meniscus deficiency. Thus, MAT is a widely accepted and recommended treatment for individuals with unicompartmental pain due to meniscus deficiency. Long-term follow-up studies have indicated that MAT yields favorable clinical outcomes, demonstrating high survivorship and low rates of serious complications. In addition, the ability of MAT to function akin to the native meniscus and shield the knee cartilage from osteoarthritis has been a subject of ongoing investigation, and recent direct magnetic resonance imaging evidence shows long-term chondroprotection following MAT. Cartilage lesions worsen during the meniscus deficiency period. Consequently, delaying MAT until patients become more symptomatic may lead to poor outcomes and low graft survivorship due to concomitant cartilage lesions. These findings prompt a reevaluation of the purpose and timing of MAT decisions for meniscectomy patients, suggesting a more proactive approach to recommending MAT, particularly for patients at high risk of postmeniscectomy syndrome and osteoarthritis progression.

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

BACKGROUND

Graft tears are common postoperative findings in meniscal allograft transplant (MAT). Graft tear in medial MAT may be different from that of lateral MAT, considering the difference between medial meniscal tears and lateral meniscal tears. Moreover, medial MAT is frequently accompanied by ligament reconstruction, which is associated with graft tear. The effect of graft tear on the long-term survivorship of medial MAT has not been investigated.

HYPOTHESIS

Graft tear would adversely affect the survivorship of medial MAT and the effect would be different according to the timing of graft tear.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 55 patients undergoing medial MAT between June 2019 and March 2000 were retrospectively reviewed. Postoperative magnetic resonance imaging (MRI) scans were reviewed to identify graft tears, and the timing of their occurrence was investigated. Postoperative MRI was performed routinely during the first postoperative year and every 2 years thereafter. The patients were classified into a no graft tear (NT) group, early graft tear (occurring within 1 year; ET) group, and late graft tear (occurring 1 year after surgery; LT) group. The survival rate of medial MAT was estimated according to graft tear, with a failure being defined as (1) reoperations including arthroplasty, realignment osteotomy, revision MAT, and meniscectomy (>50% of the graft or to the zone of the meniscocapsular junction) or (2) Lysholm score <65. Clinical scores were compared between the groups.

RESULTS

The mean follow-up duration was 8.6 ± 5.3 years. During that period, clinical failures occurred in 6 (10.9%) patients. The overall survival rate at 5 years was 94.0% (95% CI, 90.6%-97.4%). Graft tears were seen in 18 patients: 6 patients in the ET group and 12 patients in the LT group. The median time when the graft tear was noted on MRI scans was 5.5 months (range, 1-11 months) postoperatively in the ET group and 99.5 months (range, 19-264 months) postoperatively in the LT group. Five patients in the ET group had root tears, whereas 9 patients in the LT group had complex or horizontal tears. The 5-year survival rate of the ET group was 62.5% (95% CI, 41.2%-83.8%), which was significantly lower than that of the NT group (96.8%; 95% CI, 93.6%-99.9%) and the LT group (85.7%; 95% CI, 72.5%-98.9%; P = .002). The mean postoperative Lysholm scores were 85.6 ± 17.9 in the NT group, 93.0 ± 2.8 in the ET group, and 79.3 ± 11.6 in the LT group, showing no significant difference between the groups (Kruskal-Wallis test, P = .058).

CONCLUSION

Clinical relevance of graft tear that occurred after medial MAT was dependent upon its timing. ET was a risk factor for clinical failure, whereas LT did not adversely affect graft survivorship. Lysholm scores did not differ according to graft tear.