LAUSR

Objectives: Historically, radial meniscal tears were treated with partial or near- total meniscectomy which usually resulted in with poor outcomes. Radial meniscal tears function similar to a total meniscectomy and are challenging to treat. Repair of radial meniscal tears should be performed to prevent joint deterioration and the need for salvage procedures in the future. The purpose of this study was to compare three novel repair techniques for radial tears of the medial meniscus; the two-tunnel, the hybrid, and the hybrid tunnel techniques. We hypothesized that there would be no difference between the three groups in regards to gapping and ultimate failure strength. Methods: Thirty human male cadaver knees (ten matched pairs (n=20) and ten unpaired (n=10)) were used to compare the two-tunnel, hybrid, and hybrid tunnel repairs. A complete radial tear was made at the midbody of the medial meniscus. Repairs were performed according to the described techniques. Specimens were potted and mounted on a universal Instron testing machine where each specimen was cyclically loaded for 1000 cycles before experiencing a pull-to-failure. Gap distances at the tear site, ultimate failure load, and failure location were measured and recorded. Results: After 1000 cycles of cyclic loading, there was no significant difference in displacement between the two-tunnel repair (3.0 mm ± 1.7 mm), hybrid repair (3.0 mm ± 0.9 mm) or hybrid tunnel repair (2.3 mm ± 1.0 mm) (p=0.4042). On pull-to-failure testing there was also no significant difference in ultimate failure strength when comparing the two-tunnel (259 N ± 103 N), hybrid (349 N ± 149 N), or hybrid tunnel (365 N ± 146 N) repairs (p=0.26). However, the addition of vertical mattress sutures to act as a “rip stop” did significantly reduce the likelihood of the sutures pulling through the meniscus during pull-to-failure testing for the hybrid and hybrid tunnel repairs (4/16=25%) when compared to the two-tunnel repair (7/9=78%) (p=0.017). Conclusion: This study biomechanically evaluated two previously described techniques- the two-tunnel and hybrid repair- as well as one novel repair technique- the hybrid tunnel repair. The results showed equivalent biomechanical testing in regard to gap distance and pull to failure strength among each repair. The addition of the vertical mattress sutures to act as a rip stop suture was effective in preventing meniscal cut out through the meniscus. Gapping at various cycles, mm Two-Tunnel Hybrid Hybrid Tunnel p-value 0 0 ± 0 0 ± 0 0 ± 0 10 1.5 ± 1.0 1.2 ± 0.7 1.0 ± 0.6 0.412 50 1.8 ± 1.3 1.7 ± 0.7 1.4 ± 0.9 0.647 100 2.0 ± 1.4 2.0 ± 0.8 1.5 ± 0.8 0.459 250 2.4 ± 1.5 2.3 ± 0.8 1.8 ± 0.9 0.411 500 2.7 ± 1.6 2.7 ± 0.8 2.0 ± 1.0 0.347 1000 3.0 ± 1.7 3.0 ± 0.9 2.3 ± 1.0 0.4042 Pull to Failure, N Two-Tunnel Hybrid Hybrid Tunnel p-value Median ± St. Dev 259 N ± 103 349 N ± 149 365 N ± 146 0.26