Abstract
Statement: To present the early results of using new implants in the fixation of the hamstrings tendons for ACL reconstruction.
Background and Aim of the study: PINN-ACL system (Conmed UK, Linvatec UK ltd.), is a recently developed implant designed for transverse femoral fixation of hamstrings grafts in ACL reconstruction, allowing for increased pull out strength. It consists of a Graft Harness composed of Poly L-Lactic Acid with a high strength polyethylene fibre loop and a Cross pin composed of Self-Reinforced PLLA. Tibial fixation is achieved by a bioabsorbable Matryx Interference Screw; composed of Self-Reinforced 96L/4D PLA and beta-Tri-Calcium Phosphate(Linvatec Biomaterials ltd.)
We describe our early experience with this new system, the technique of fixation, short-term clinical results, functional outcome and MRI features of these implants.
Materials and Methods: A prospective data collection was undertaken over the past 12 months. The operative steps:, four strand hamstring preparation, tensioning, femoral fixation of graft with graft harness and cross pin, tensioning the graft and tibial fixation with bio- absorbable interference screw. More than 80% of the cases were performed without tourniquet. The follow up were made at 2,12,24,36 weeks and further evaluation as needed for the purpose of the study. Outcomes were assessed with Lysholm, Tegner and IKDC scores.
Results: 24 cases were performed in 23 cases. The mean age, gender and laterality were 34(17–51), 1.7M: 1F, 14L:10 R. The injury pattern: sports (77%) and RTA (11%)
Tunnel view of the harness was excellent in 79%. Linvatec Tensioner was used in 60%. Graft was not detached in 20%. The mean follow up period was 7 months (2 –12). At last follow up Lachman and pivot shift were negative in 85% and grade 1 in 15%, The mean postoperative scores were Tegner-7 (5–10), Lysholm-7 (5–10) and IKDC-71 (57–93) respectively.
1 wound problem required washout. The tibial screw twisted off at final turn in 1 patient. The cross pin drill missed the guide in 1 patient.
At 32 weeks MRI scan: the implants were still evident, However apart form 1 patient, there was no surrounding bone reaction and none showed tunnel widening.
Conclusion: Early results are encouraging, both operative technique and fixation. However, harness size is limited to 8 and 9 mm only and the implants were still evident at a mean period of 32 weeks against the manufactures claim of 24 weeks.
Correspondence should be addressed to Mr T Wilton, c/o BOA, BASK at the Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London WC2A 3PE, England.
