Outcomes of 11 dogs with short radius syndrome treated with acute arthroscopically assisted ulnar shortening.

OBJECTIVE: To describe the short-term outcome of acute arthroscopically assisted ulnar shortening (AUS), to treat short radius syndrome in dogs. STUDY DESIGN: Case series. ANIMALS: Eleven client owned dogs. METHODS: Records of dogs that had undergone AUS for treatment of short radius syndrome were reviewed for inclusion. Reporting data included among others pre- and postoperative radioulnar, humeroradial and humeroulnar distances, lameness scores, surgical times, complications and clinical outcome. RESULTS: Following AUS, radiohumeral articulation was improved in all dogs. Median presurgery radioulnar, humeroradial and humeroulnar values were 4.5, 3.2, and 2.2 mm and were improved with surgery by a median of 3.2, 1.8, and 1.2 mm, respectively. Median surgery time was 140 min. Median time to bone healing was 8 weeks (range: 4-14). Median time to last follow-up was 9 weeks (4-468). Median lameness score (scale 0-4) improved from 2 to 1. No major complications were reported. Short-term clinical outcome was graded by the surgeons as full function in four cases and acceptable function in seven. CONCLUSION AND CLINICAL RELEVANCE: Radiographic and arthroscopic radiohumeral articulation were improved and short-term clinical improvement was documented following AUS in all 11 dogs.

Effect of Stem Positioning on Biomechanical Performance of a Novel Cementless Short-Stem Canine Total Hip Implant.

OBJECTIVE: The aim of this study was to evaluate the effect of stem positioning on the biomechanical performance of a novel, collared, short-stem total hip implant under compression and torsion ex vivo. STUDY DESIGN: Six canine cadaveric femurs were implanted with a collared short-stem femoral implant. Canal flare index (CFI), stem angle, absolute and relative cut heights and relative size were measured radiographically and used as independent variables. Biomechanical performance of the construct was evaluated using physiologic loading (loading) and supraphysiologic loading (failure) protocols. RESULTS: During loading protocols, compressive stiffness was influenced by absolute cut height (p = 0.018). During failure protocols, peak torque was influenced by CFI (p = 0.004) and craniocaudal relative size (p = 0.005). Peak load and torsional stiffness were not impacted by any of the radiographic variables (p > 0.05). Three of six femurs developed longitudinal fractures originating at the medial calcar at the time of failure. CONCLUSION: The biomechanical performance of the collared short-stem implant was positively impacted by preserving more of the femoral neck, having a higher CFI and using a smaller implant size relative to the femoral neck isthmus.

Radiographic and Biomechanical Assessment of Three Implant Designs for Canine Cementless Total Hip Replacement.

OBJECTIVE: The aim of this study was to evaluate the relationship between radiographic fit/fill measurements and biomechanical performance of three canine cementless total hip implant designs using an in vitro biomechanical testing protocol that replicates compression and torsion. STUDY DESIGN: Eighteen (six/group) canine cadaveric femurs were implanted with one of three cementless total hip implant designs: (1) collarless, (2) collared or (3) lateral bolt stems. Femoral length, canal flare index (CFI), canal fill, stem fit, stem level and stem angle were measured as independent variables. Biomechanical performance was tested using physiological, non-destructive gait loading (loading protocols) and destructive testing (failure protocols). RESULTS: During loading protocols, compressive stiffness was influenced by stem level (p < 0.05) and torsional stiffness was influenced by stem level and CFI for collarless stems (p < 0.05). During failure protocols, peak load was influenced by mediolateral (ML) stem angle (p < 0.05) and CFI (p < 0.01) for collarless stems and CFI for lateral bolt stems (p < 0.05). Peak torque was influenced by ML stem angle, craniocaudal stem angle and CFI for collarless stems (p < 0.05) and average ML fill for collared stems (p < 0.05). CONCLUSION: Biomechanical performance of collarless stems in cementless hip arthroplasty is more impacted by radiographic fit/fill than lateral bolt and collared stems. As a result, collarless stems may be more dependent on preoperative fit and intraoperative precision.

A Biomechanical Comparison of Four Hip Arthroplasty Designs in a Canine Model.

OBJECTIVE: The aim of this study was to develop an in vitro biomechanical protocol for canine cementless hip arthroplasty that represents physiological gait loading (compression and torsion) and to evaluate if three alternative implant designs improve fixation compared with the traditional collarless, tapered stem in the clinically challenging case of moderate canal flare index. STUDY DESIGN: Twenty-four (six/group) laboratory-prepared canine constructs were tested using a simulated gait and overload (failure) protocol. Construct stiffness, failure load/displacement and migration were measured as outcome variables. RESULTS: Simulated gait loading did not show any significant differences between implant types for peak displacement, peak rotation, torsional stiffness, subsidence or inducible displacement. The collared and collarless stem groups were stiffer in compression compared with the collarless with a lateral bolt and short-stem groups. Increasing the loading above simulated gait showed significant reductions in compressive and torsional stiffness for all implant constructs. Despite the reductions, the short-stem group showed significantly higher stiffness compared with the other three groups. CONCLUSION: Peak failure loads (compressive and torsional) in this study were approximately four to seven times the simulated gait loading (430 N, 1.6 Nm) regardless of implant type and highlight the importance of limiting activity level (trotting, jumping) following hip replacement in the postoperative period and during the osseointegration of the implant.

Gene expression in hip soft tissues in incipient canine hip dysplasia and osteoarthritis.

Canine hip dysplasia and developmental dysplasia of the human hip share demographic, phenotypic, and clinical features including the predisposition to develop osteoarthritis in affected joints. To support the results of genetic mapping studies for CHD and its concomitant osteoarthritis with functional information, we performed RNA-seq on hip capsule and teres ligament of affected and unaffected dogs. RNA seq showed that expressed genes segregated according age, capsule or ligament, and hip phenotype. Expression of HHIP, DACT2, and WIF1 was significantly higher in capsule from control hips than dysplastic hips indicating a disruption of the hedgehog signaling pathway. Expression of SPON 1, a key component of the WNT pathway, was increased significantly in both dysplastic capsule and ligament while FBN2 and EMILIN3 were significantly increased in dysplastic capsule. Of genes associated with human hip osteoarthritis, expression of ACAN, IGF1, CILP2, COL11A1, COL8A1, and HAPLN was increased significantly in dysplastic capsule. The significant increase in expression of PLA2F, TNFRSF, TMEM, and IGFBP in dysplastic capsule indicated an injury response. Gene set enrichment analysis revealed that genes involved in extracellular matrix structure, epithelial to mesenchymal transition, myogenesis, growth factor signaling, cancer and immune pathways were enriched in dysplastic capsule. For teres ligament from dysplastic joints, genes in retinoic signaling pathways and those encoding extracellular matrix molecules, but not proteoglycans, were enriched. Hip tissues respond to abnormal mechanics early in dysplastic hip development and these pathways present targets for intervention in the early synovitis and capsulitis secondary to canine and human hip dysplasia. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:313-324, 2019.

Performance evaluation and validation of the animal trauma triage score and modified Glasgow Coma Scale with suggested category adjustment in dogs: A VetCOT registry study.

OBJECTIVE: To examine the animal trauma triage (ATT) and modified Glasgow Coma Scale (mGCS) scores as predictors of mortality outcome (death or euthanasia) in injured dogs. DESIGN: Observational cohort study conducted from September 2013 to March 2015 with follow-up until death or hospital discharge. SETTING: Nine veterinary hospitals including private referral and veterinary teaching hospitals. ANIMALS: Consecutive sample of 3,599 dogs with complete data entries recruited into the Veterinary Committee on Trauma patient registry. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We compared the predictive power (area under receiver operating characteristic [AUROC]) and calibration of the ATT and mGCS scores to their components. Overall mortality risk was 7.3% (n = 264). Incidence of head trauma was 9.5% (n = 341). The ATT score showed a linear relationship with mortality risk. Discriminatory performance of the ATT score was excellent with AUROC = 0.92 (95% confidence interval [CI] 0.91 to 0.94) and pseudo R2 = 0.42. Each ATT score increase of 1 point was associated with an increase in mortality odds of 2.07 (95% CI = 1.94-2.21, P < 0.001). The "eye/muscle/integument" category of the ATT showed poor discrimination (AUROC = 0.55). When this component together with the skeletal and cardiac components were omitted from calculation of the overall score, there was no loss in discriminatory capacity (AUROC = 0.92 vs 0.91, P = 0.09) compared with the full score. The mGCS showed good performance overall, but performance improved when restricted to head trauma patients (AUROC = 0.84, 95% CI = 0.79-0.90, n = 341 vs 0.82, 95% CI = 0.79-0.85, n = 3599). The motor component of the mGCS showed the best predictive performance (AUROC = 0.79 vs 0.66/0.69); however, the full score performed better than the motor component alone (P = 0.002). When assessment was restricted to patients with head injury (n = 341), the ATT score still performed better than the mGCS (AUROC = 0.90 vs 0.84, P = 0.04). CONCLUSIONS: In external validation on a large, multicenter dataset, the ATT score showed excellent discrimination and calibration; however, a more parsimonious score calculated on only the perfusion, respiratory, and neurological categories showed equivalent performance.