Introduction
Previous studies evaluated transosseus pullout (TPO) refixation compared to arthroscopic suture anchor (SA) refixation of meniscal root tears. Current SA procedures require a posterior portal with risk of damage to neurovascular structures and TPO refixation requires extracortical fixation. Therefore, a new all-suture anchor refixation was developed. In this procedure, an all-suture anchor is arthroscopically pulled-in not requiring a posterior portal nor extracortical fixation nor interference in possible tunnel conflict in multi-ligament reconstruction. The study aimed at the evaluation of the biomechanical capabilities of this new trans-tibial pull-in (TPI) technique in comparison to standard TPO and SA repair. We hypothesized that the biomechanical specifications of meniscal root tear repair using all-suture anchors in the TPI technique are comparable to standard techniques.
Materials And Methods
Thawed fresh porcine proximal tibias were used. The posterior medial meniscus root was cut 5mm from its insertion. In TPI, a modified a double loaded all-suture anchor and pulled it into the subcortical bone through the tunnel at the meniscal root insertion instead of tapping it in. Transtibial drilling was performed analogous to the TPO technique. The root was fixed to the anchor with 2 sutures analogous to the SA technique. SA reconstruction was applied from posterior. 4 groups were defined (n=10): 1. native meniscal root (NM), 2. TPO repair with 2 sutures (#2Hi-Fy, Conmed, USA) and extracortical flipptack fixation (Storz, Germany), 3. double loaded SA repair (SuperRevo, Conmed, USA), 4. double loaded new TPI repair (Y-KnotFlex 1.8 mm, Conmed, USA). A servohydraulic testing device (Zwick, Germany) was used for testing. The meniscus was clamped to the testing device and the proximal tibia was potted with PMMA into a cylinder. The prox. tibia plateau was mounted 90° to the testing device (posterior part up) and force was applied in posterior direction to the NM. Cyclic loading with subsequent load to failure (LTF) (preload 2N, 1000 cycles with 5-20N; 0.5Hz) was applied and LTF, stiffness (N/mm), displacement at LTF (mm) and displacement at cyclic loading (mm) were calculated. Statistical analysis was performed with Graph Pad Prism 9 and a 1-way ANOVA was used for displacement in cyclic loading and at failure and a Kruskal-Wallis test was used for LTF and stiffness. Significancy was defined as p<0,05.
Results
TPI showed similar displacement after 1000 cycles (TPI 2,30±0,75 mm vs. SA 2,54±0,79 mm vs. TPO 2,10±0,68 mm; n.s.) and comparable stiffness (TPI 36,76±12,72 N/mm, SA 36,15±10,12 N/mm, TPO 33,56±6,16 N/mm; n.s.) compared to SA/TPO. TPI showed significantly increased displacement at failure (TPI 16,91±8,85 mm, SA 9,92±2,92 mm, TPO 10,05±2,42 mm; p<0,05). LTF increased in TPI compared to SA or TPO (TPI 206,2±86,5 N, SA 251,4±52,8 N, TPO 233,4 ± 49,9 N; n.s.). Final failure was always a suture cut out of the meniscus in all groups.
Conclusion
The TPI technique showed comparable biomechanical properties compared to the TPO/SA technique. However, all techniques did not reach the biomechanical properties of the NM.