Biomechanical analysis of a new 8-strand technique for flexor tendon repair.

We sought to compare the strength and rupture sites of a new 8-strand suture technique with those of an established 6-strand flexor tendon repair through biomechanical analysis. This new 8-strand suture pattern places minimal suture material in the remodeling zone and focuses on protecting the knot, a well-known weak point of the suture construct. The knot was buried within the tendon so as to not interfere with tendon gliding. In a biomechanical simulation, strength and rupture sites were compared with those of the 6-strand repair. We repaired a total of 54 porcine flexor tendons using one of the two techniques (n=27 each). Tensile strength at 2-mm gap formation and ultimate failure load were determined. Afterwards, we dissected the tendons to identify the rupture site of the suture material. The new 8-strand suture had a significant higher ultimate load to failure (87.7N) and 2-mm gap load (71.6N) compared to the 6-strand technique (57.7N and 45.9N) (P<0.001). Whereas the rupture site of the core suture in the 6-strand technique was mainly located next to the knot (81.5%), the suture seemed to fail independently from this weak spot in the 8-strand technique (11.1%). This new 8-strand technique achieves a strong flexor tendon repair in a biomechanical model. Additional cross-locking on either side of the knot seems to contribute to the repair's strength. The resulting higher ultimate failure load and 2-mm gap load may allow more aggressive active motion-based postoperative rehabilitation.

[Osteoconductive behaviour of beta-tricalcium phosphate ceramics in osteoporotic, metaphyseal bone defects of the distal radius]. / Osteokonduktive Eigenschaften von Beta-Trikalzium-phosphat in osteoporotischen, metaphysären Radiusdefekten.

BACKGROUND: Surgical treatment of osteoporotic distal radius fractures with locking plates does not completely prevent loss of reduction. Additional bone deficit stabilisation with the use of bone substitute materials is receiving increased attention. Most knowledge on the in vivo behavior of bone substitutes originates from a small number of animal models after its implantation in young, good vascularized bone. PURPOSE: This paper investigates the osteoconductivity, resorption and biocompatibility of beta-tricalcium phosphate as a temporary bone replacement in osteoporotic type distal radius fractures. PATIENTS AND METHODS: 15 bone samples taken from the augmented area of the distal radius of elderly people during metal removal were examined. RESULTS: The material was found to be osteoconductive, good degradable, and biocompatible. Degrading process and remodelling to woven bone seem to require more time than in available comparative bioassays. CONCLUSIONS: The material is suitable for temporary replacement of lost, distal radius bone from the histological point of view.