VCOT May 2025 – Ortho Part 2: TTT Spacer Pins & The Working Length Myth

In this Simini Small Animal Surgery Podcast episode, we continue our orthopedic coverage from the May 2025 issue of Veterinary and Comparative Orthopaedics and Traumatology (VCOT) with two studies that challenge long-held assumptions about orthopedic fixation. One paper examines whether a novel spacer pin technique can provide the same stability as traditional tibial tuberosity transposition fixation while reducing implant-related complications. The second tackles one of the most debated concepts in fracture fixation: plate working length and whether leaving holes empty near a fracture gap truly provides biomechanical advantages.In this episode:✅ Sullivan et al. — An ex vivo biomechanical study comparing three fixation methods for tibial tuberosity transposition (TTT) in the treatment of medial patellar luxation. The authors evaluated traditional tension band wiring, dual-pin fixation, and a novel spacer pin technique. All constructs demonstrated comparable stiffness and failure strength, with each tolerating more than 1,000 Newtons of force before failure. Importantly, the spacer pin avoided implant placement directly through the patellar ligament insertion, potentially reducing soft tissue irritation and implant-associated complications while maintaining equivalent biomechanical stability. ✅ Trefny et al. — A biomechanical investigation of working length in locking compression plate constructs using a distal radius fracture model. Contrary to conventional wisdom, constructs with short working lengths (screws placed adjacent to the fracture gap) were approximately 30% stiffer and generated lower plate strain than constructs with longer working lengths. While long working length constructs initially benefited from load sharing through transcortical contact, the authors highlight the biologic risks associated with repeated bone-end contact, including high interfragmentary strain, bone resorption, and eventual implant fatigue failure. Together, these studies demonstrate that orthopedic success often comes down to understanding where forces are actually being transmitted—and avoiding assumptions that may no longer hold true.🎓 Journal Articles DiscussedSullivan et al. — Biomechanical Comparison of Spacer Pin Fixation to Two Established Methods of Tibial Tuberosity Transposition Stabilization in DogsTrefny et al. — Effect of Plate Screw Configuration on Construct Stiffness and Plate Strain in a Synthetic Short Fragment Small Gap Fracture Model Stabilized with a 12-Hole 3.5-mm Locking Compression Plate📚 From the May 2025 issue of VCOT🎁 Want to learn more about Simini Protect Lavage or request a sample?Learn More: www.simini.comRequest a Sample: https://www.simini.com/evaluation-kit