Tendon injury poses a unique clinical challenge because even with optimal treatment and therapy, the healed tendon does not recover its biochemical and mechanical properties to preinjury levels.1 Patellar tendon ruptures are rare musculoskeletal injuries in dogs.2,3 Ruptures of the patellar tendon are particularly detrimental because of inability to extend the stifle joint, which is attributed to the loss of the quadriceps mechanism.4–6 Patellar tendon rupture is most commonly described as occurring in the midsubstance region,7 but in the authors' experience, rupture at the proximal aspect also occurs.
Rapid surgical intervention in dogs with ruptured patellar tendons is crucial to ensure rapid healing without gap formation and allow for a return in tensile strength and function with minimal scar formation.8 Several techniques for tenorrhaphy in dogs have been previously described.2,3,5,8–10 However, repair of patellar tendon rupture near its origin at the patellar apex may prove challenging because there can be minimal tendon substance remaining and minimal bone stock to facilitate a secure reattachment.11
Previously described techniques for tenorrhaphy such as the 3-loop pulley, Bunnel-Mayer, Krackow, and Kessler locking-loop patterns can be modified to attach tendon directly to bone.8,12,13 Bone tunnels are a primary way of securing the attachment, but the need for comparatively large suture sizes to achieve the required strength results in large bone tunnels that increase the potential for patellar fracture. However, compared with similar-diameter monofilament sutures, UHMWPE suture provides twice the tensile strength and a higher resistance to elongation14; thus, similar results can be achieved with smaller-diameter suture and smaller bone tunnels.
The purpose of the study reported here was to compare use of a 3LSLS technique with use of the previously described M3LP technique12 to repair rupture of the proximal aspect of patellar tendons in limbs from canine cadavers. We hypothesized that tendons repaired with the 3LSLS technique would require a significantly greater force load to develop a 1-mm gap, a 3-mm gap, and failure of the repair than would tendons repaired with the M3LP technique.
Funded by the University of Florida College of Veterinary Medicine Small Animal Clinical Sciences Departmental funds.
Matthew Johnson is a consultant for Arthrex Vet Systems but has no direct financial connection or benefit from use of the products in this study.
The authors thank Dr. Diego Sobrino and CJ Travers for technical assistance and data collection.
Three-level self-locking suture
Modified 3-loop pulley
Materials testing system
Percutaneous Achilles Repair System (PARS), Arthrex, Naples, Fla.
858 Mini Bionix, MTS Systems Corp, Eden Prairie, Minn.
Minitab, version 17.1.0, State College, Pa.
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