Mechanical evaluation of a novel angle-stable interlocking nail in a gap fracture model.

OBJECTIVE: To describe the mechanical characteristics of a novel angle-stable interlocking nail (NAS-ILN) and compare them to those of a locking compression plate (LCP) by using a gap-fracture model. STUDY DESIGN: Experimental study. SAMPLE POPULATION: Synthetic bone models. METHODS: Synthetic bone models simulating a 50 mm diaphyseal comminuted canine tibial fracture were treated with either a novel angle-stable interlocking nail (NAS-ILN) or a locking compression plate (LCP). Maximal axial deformation and load to failure in compression and 4-point bending, as well as maximal angular deformation, slack, and torque to failure in torsion, were statistically compared (P < .05). RESULTS: In compression, the maximal axial deformation was lower for NAS-ILN (0.11 mm ± 0.03) than for LCP (1.10 mm ± 0.22) (P < .0001). The ultimate load to failure was higher for NAS-ILN (803.58 N ± 29.52) than for LCP (328.40 N ± 11.01) (P < .0001). In torsion, the maximal angular deformation did not differ between NAS-ILN (22.79° ± 1.48) and LCP (24.36° ± 1.45) (P = .09). The ultimate torque to failure was higher for NAS-ILN (22.45 Nm ± 0.24) than for LCP (19.10 Nm ± 1.36) (P = .001). No slack was observed with NAS-ILN. In 4-point bending, the maximal axial deformation was lower for NAS-ILN (3.19 mm ± 0.49) than for LCP (4.17 mm ± 0.34) (P = .003). The ultimate bending moment was higher for NAS-ILN (25.73 Nm, IQR [23.54-26.86] Nm) than for LCP (16.29 Nm, IQR [15.66-16.47] Nm) (P = .002). CONCLUSION: The NAS-ILN showed greater stiffness in compression and 4-point bending, and a greater resistance to failure in compression, torsion, and 4-point bending, than LCP. CLINICAL IMPACT: Based on these results, NAS-ILNs could be considered as alternative implants for the stabilization of comminuted fractures.

Retrospective study of the early clinical experience with a precontoured angle-stable interlocking nail for fracture repair in dogs and cats.

OBJECTIVE: To report indications, outcomes, and complications with a precontoured angle-stable interlocking nail (CAS-ILN). ANIMALS: 90 client-owned animals. METHODS: Dogs and cats treated with the CAS-ILN between 2020 and 2022 were retrospectively reviewed. Collected data included body weight, fracture configuration, percentage of medullary canal filled, limb alignment, complications, and follow-up. Favorable outcomes were defined when full functional restoration was observed. RESULTS: Thirty-eight dogs and 52 cats were included. Median body weight was 4.3 kg (range, 1.5 to 6.7 kg) for cats and 25 kg (range, 6.8 to 54 kg) for dogs. A total of 54 femurs, 31 tibias, and 5 humeri were treated, including 65 comminuted fractures and 26 metaphyseal fractures. The median percentage of medullary canal occupied by the nail was 76.5% (range, 53% to 97.6%). Radiographic postoperative bone alignment was good in 85.5% (59/69) and satisfactory in 10 cases. The median duration of follow-up (57/90) was 476 days (range, 56 to 1,057 days). In the perioperative period (0 to 12 weeks), lameness had resolved or was mild in all (51/52) but 1 case. In the long-term postoperative period (> 12 months), 97.1% (34/35) of cases showed restoration of full function and 1 case had an unacceptable function. An overall complication rate of 11.5% (7/61) was reported including 1 catastrophic and 6 major complications. CLINICAL RELEVANCE: Long-term functional outcomes following the CAS-ILN were favorable in 97.1% (34/35) of cases. Complication rates were comparable to previous studies. The CAS-ILN appears to be an alternative surgical option for most long-bone fracture repairs.

Concurrent bucket handle meniscal tear treated with arthroscopic partial meniscectomy does not influence midterm outcomes after tibial plateau leveling osteotomy.

OBJECTIVE: To assess the effect of arthroscopic partial meniscectomy in dogs with bucket handle meniscal tears and tibial plateau leveling osteotomy (TPLO), compared with dogs with cranial cruciate ligament rupture and no meniscal tear treated by TPLO alone. ANIMALS: 30 client-owned dogs with cranial cruciate rupture treated by either TPLO and arthroscopy alone if the meniscus was normal (normal meniscus [NM] group, n = 14) or by TPLO and an arthroscopic partial meniscectomy if a bucket handle tear was diagnosed (meniscal tear [MT] group, n = 16). METHODS: Medical records, lameness score, and symmetry gait analysis parameters were retrospectively collected from patient records preoperatively (PreO), then at 1, 3, and 6 months postoperatively (M1, M3, and M6, respectively). Osteoarthritic (OA) radiographic score was performed and compared at PreO and M6. RESULTS: PreO gait analysis parameters were lower in the MT group (P < 0.005). In the MT group, the lameness score significantly improved between PreO and M1, and there were no significant differences between groups at M6. OA score was significantly higher in the MT group at PreO and M6. However, postoperative progression of OA did not differ between the 2 groups (P = 0.16). CLINICAL RELEVANCE: Treatment for meniscal tear results in a significant improvement in lameness, with postoperative outcomes at 6 months comparable with dogs with intact menisci. Despite having significant osteoarthritic lesions at all time points, the progression of osteoarthritis is similar between dogs with meniscal tears and those with intact menisci.

Ex vivo postimplantation biomechanical properties of a press-fit cementless femoral stem with transfixation pin for canine total hip replacement.

OBJECTIVE: To compare ex vivo postimplantation biomechanical characteristics of 3 implants for canine total hip replacement: a cementless press-fit femoral stem with a pin in the femoral neck (p-pfFS), a press-fit cementless femoral stem without this pin (pfFS), and a cemented femoral stem (cFS). SAMPLE: 18 cadaveric femurs from 9 dogs. PROCEDURES: Femurs were assigned randomly to 3 groups, and biomechanical testing was performed by measuring vertical displacement during cyclic loading and resistance to failure with compression parallel to the longitudinal axis of the femur. Force-displacement curves were assessed for failure tests, and work necessary for failure was calculated. RESULTS: No significant differences were observed in vertical displacement during cyclic loading (P = .263) or work necessary for failure (P = .079). Loads to failure for cFS and p-pfFS implants were significantly greater than that for the pfFS, but no significant difference in load to failure was observed between cFS and p-pfFS implants (P = .48). CLINICAL RELEVANCE: Cementless femoral stems with a transfixation pin offer significantly greater immediate resistance to failure to compressive loads parallel to the longitudinal axis of the femur than standard cementless stems, and a level of stability comparable to that of cemented stems. p-pfFS implants may be valuable in total hip replacement, potentially reducing the risk of fracture during the early postoperative period prior to osteointegration.

Anatomical features of the canine C2-C3 spinal cord vascular environment.

OBJECTIVE: Interarcuate branch (IAB) is a vascular structure, particularly developed in C2-3 intervertebral space, forming a dorsal bridge that connects ventral venous plexi in the vertebral canal. While precisely described in the human, the precise anatomical features of IABs have not been reported in the veterinary literature. The purpose of this study is to describe the features and relations of IABs in the C2-3 vertebral canal. ANIMALS: 10 dogs were enrolled; 5 dogs for necropsy and 5 dogs for histology. PROCEDURES: The ventral venous plexi in the cervical spine of 5 dogs were injected with latex and underwent vertebral canal dissection for visual assessment of the IAB. Two out of 5 dogs were injected with the addition of barium sulfate and underwent a CT scan. The C2-3 regions of 5 small-breed dogs were harvested for histological examinations. RESULTS: IABs arose from the ventral venous plexus at the level of the intervertebral vein; they originated from 2 separate branches located caudally and cranially to the intervertebral foramen, forming a ventrodorsal triangle surrounding the spinal nerve root. No dorsal anastomosis was observed on the CT scan nor at dissection but were observed histologically. A cervical fibrous sheath was observed all around the vertebral canal. CLINICAL RELEVANCE: IABs are voluminous venous structures at the C2-3 intervertebral space in dogs and found within a split of the cervical fibrous sheath, which is adherent to the interarcuate ligament and the ligamentum flavum. This anatomical description is paramount when planning an approach to the C2-3 intervertebral space.