Risk factors for loosening of cementless threaded femoral implants in canine total hip arthroplasty

Complications and Long-Term Outcome in 30 Canine Total Hip Arthroplasties Using a Second-Generation Selective Laser Melted Screw Cup

OBJECTIVE

 The aim of this study was to report complications and outcomes of a cementless total hip arthroplasty (THA) system with a second-generation selective laser-melted screw cup (SCSL).

STUDY DESIGN

 All THA using the SCSL performed at a single institution between January 2017 and November 2022 were retrospectively evaluated. Patients with a minimum follow-up period of 12 months and complete medical records were included and analyzed for radiographic and clinical outcomes.

RESULTS

 Thirty THA with SCSL in 23 dogs were included in this study. Complications were observed in seven hips, comprising two minor and five major complications, with two hips experiencing two major complications. Among these seven major complications, six were associated with the femoral implant and one involved cup luxation. Of the 30 THA, 4 were explanted, while 26 remained in place for a median follow-up of 17.5 months (range, 12-38 months).

CONCLUSION

 No cases of late aseptic loosening were observed with SCSL. THA using SCSL helps reduce cup-associated complications and is appropriate for THA surgery, and the overall complication rate is comparable with that of other single-implant systems. Nevertheless, four hips were explanted.

Case report: Total hip replacement using Innoplant system in a dog with chronic hip luxation and contralateral pelvic limb amputation

A 6-year-old female neutered Border Collie presented with an inability to walk. The patient had undergone pelvic limb amputation over a year prior. Orthopedic examination revealed discomfort during hip manipulation, and radiographic examination revealed chronic hip luxation. Total hip replacement was performed using the InnoPlant system, which includes modular screw-in cementless pieces to improve implant stability. Cage rest was for the first four postoperative weeks. Subsequently, assistance was provided while standing until the patient could stand unassisted at 10 postoperative weeks. The clinical and radiological outcomes were excellent 3 months postoperatively. Since it is a new system, there are no data regarding the use of the components of the Innoplant system in dogs with a contralateral amputated pelvic limb. This is the first report describing the use of the Innoplant system for total hip replacement in a dog with a contralateral amputated pelvic limb. Based on the clinical outcomes of this case, the use of an Innoplant prosthesis can be an effective treatment option for dogs with contralateral amputated limbs.

Intra-Articular Administration of a Synthetic Lubricin in Canine Stifles

OBJECTIVE

 The aim of this study was to evaluate the functional, systemic, synovial and articular changes after intra-articular administration of a synthetic lubricin within healthy canine stifles.

STUDY DESIGN

 A prospective randomized blinded placebo-controlled study composed of 10 dogs equally divided into either a treatment group (intra-articular synthetic lubricin injection, n = 5) or control group (saline, n = 5). Clinical (orthopaedic examination, gait observation, gait analysis), biochemical (complete blood count and biochemistry profile) and local tissue outcomes (joint fluid analysis, joint capsule and articular cartilage histopathology) were evaluated over a time period of 3 months.

RESULTS

 No significant differences between the treatment group and control group were identified with regard to baseline patient parameters. No clinically significant orthopaedic examination abnormalities, gait abnormalities, biochemical alterations, joint fluid alterations or histopathological alterations were identified over the course of the study.

CONCLUSION

 The synthetic lubricin studied herein is both biocompatible and safe for a single administration within the canine stifle joint. Further research is necessary to evaluate the clinical efficacy of the synthetic lubricin in canine osteoarthritic joints.

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.

Micrometer-Sized Titanium Particles Induce Aseptic Loosening in Rabbit Knee

Wear debris induced aseptic loosening is the leading cause of total knee arthroplasty (TKA) failure. The complex mechanism of aseptic loosening has been a major issue for introducing effective prevention and treatment methods, so a simplified yet efficient rabbit model was established to address this concern with the use of micrometer-sized titanium particles. 20 New Zealand white rabbits were selected and divided into two groups (control = 10, study = 10). A TKA surgery was then performed for each of them, with implantation of a titanium rod prosthesis which was coated evenly with micrometer-sized titanium in the study group and nothing in the control group, into right femoral medullary cavity. After 12 weeks, all the animals were euthanized and X-ray analyses, H&E staining, Goldner Masson trichrome staining, Von Kossa staining, PCR, and Western blotting of some specific mRNAs and proteins in the interface membrane tissues around the prosthesis were carried out. The implantation of a titanium rod prosthesis coated with 20 μm titanium particles into the femoral medullary cavity of rabbits caused continuous titanium particle stimulation around the prosthesis, effectively inducing osteolysis and aseptic loosening. Titanium particle-induced macrophages produce multiple inflammatory factors able to activate osteoclast differentiation through the OPG/RANKL/RANK signaling pathway, resulting in osteolysis while suppressing the function of osteoblasts and reducing bone ingrowth around the prosthesis. This model simulated the implantation and loosening process of an artificial prosthesis, which is an ideal etiological model to study the aseptic prosthetic loosening.

Complications of porous-coated press-fit cementless total hip replacement in dogs

Objective: To report postoperative complications using a commercially available porous-coated press-fit cementless total hip replacement (THR) system in dogs.

Methods: Medical records were reviewed for client-owned dogs with hip pathologies requiring THR. A minimum of six-week postoperative orthopaedic examination and orthogonal pelvic radiographs were used to assess outcome and complications in the perioperative period. Referring veterinarian medical records, phone interviews with clients, or both were used to assess long-term functional outcome and complications.

Results: Bilateral THR was performed in 36 dogs, and unilateral in 147 dogs, making a total of 219 THR procedures in 183 dogs. A total complication rate of 31.1% (68/219) was observed. A catastrophic complication was observed in 8.2% (n = 18), a major complication in 9.6% (n = 21), and a minor complication in 13.2% (n = 29) of procedures. The most common complications were intra-operative femoral fissure (n = 46), diaphyseal femoral fracture (n = 15), and coxofemoral luxation (n = 9). Full return to function was achieved in 88.1% of procedures with a median follow-up period of 42 months.

Clinical significance: Porous-coated press-fit cementless collarless total hip replacements have a high complication rate. The majority of complications occur intra-operatively or perioperatively, with few complications occurring beyond 12 weeks postoperatively. Both fissure fractures and diaphyseal femoral fractures carry a favourable prognosis with immediate cerclage wiring and plate fixation, respectively.

INNOPLANT Total Hip Replacement System

Total hip replacement is a salvage procedure that is done to alleviate discomfort secondary to osteoarthritis in the hip, which is most often a result of hip dysplasia. Commercially available total hip replacement implants for small animal patients are classified as cemented or cementless. The INNOPLANT Total Hip Replacement system includes modular, screw-in cementless components that were developed to improve implant stability by maintaining as much normal anatomic structure, and by extension biomechanics of the coxofemoral joint, as possible. As a newer system, there are few data and no long-term studies available in the veterinary literature.