Veterinary Clinical Sciences - Theses
Permanent URI for this collection
Search Results
1 - 1 of 1
-
ItemMetal endoprostheses for limb salvage surgery in dogs with distal radial osteosarcoma: evaluation of first and second generation metal endoprostheses and investigation of a novel endoprosthesis( 2017)Osteosarcoma (OSA) is the most commonly diagnosed primary bone tumour in dogs, usually affecting middle-aged, large breed dogs. The standard of care surgical treatment for local tumour control in dogs with osteosarcoma is limb amputation; however limb-sparing surgery is gaining wider acceptance as an alternative surgical treatment. All limb sparing techniques show high complication rates, including infection, construct failure or fracture and local recurrence. Metal endoprosthesis (EN) limb-sparing surgery was developed to overcome limitations of other techniques, including access to specialised equipment and facilities such as radiation therapy or bone bank facilities. The first generation of metal EN (GEN1) was shown to be biomechanically superior, but not clinically different to the cortical allograft. A second generation metal EN (GEN2) was developed but biomechanical studies and clinical outcomes have not been reported other than in single case reports. The first component of this thesis is a multi-institutional retrospective case series that evaluated surgical and oncologic outcomes for dogs treated with GEN1 or GEN2 for OSA of the distal radius. Records from 45 dogs with distal radial OSA were examined; 28 dogs received GEN1 and 17 dogs received GEN2. One or multiple complications occurred in 43 dogs (96%, 14 minor, 29 major) including 35 with infection (78%), 16 with implant-related complication (36%) and 11 with local recurrence (24%). This study showed no significant difference in case (surgical or oncologic) outcomes between dogs receiving GEN1 and GEN2 endoprosthesis for limb-sparing surgery of the distal radius. The frequency of complications, including infection and those implant-related, remains unacceptably high for both generations of endoprosthesis. Further refinement of the endoprosthesis or re-evaluation of the surgical technique for implantation of the endoprosthesis is indicated. A finite element (FE) model of the canine forelimb has been designed by a multi-disciplinary team from Colorado State University. Evaluation of GEN2 in the FE model predicted stresses in the proximal radius that exceeded the fatigue limit and yield stress of 316L stainless steel; the predicted stresses of GEN2 are too high for sustained performance. An engineering specific approach was taken to design a novel EN and evaluation in the FE model resulted in 50% reduction in peak stresses in the radial screws compared to GEN2 in the FE model. The second component of this thesis is evaluation of the suitability of the novel EN for clinical use. The novel EN prototypes were manufactured using three-dimensional printing (3DP) in plastic and stainless steel. Three size variations of the novel EN were designed using a computer-aided design (CAD) program and implanted into large breed cadaver radii. There was a large variation in radius morphology between and within large breeds; making the novel EN unlikely to be suitable as an off the shelf implant. The most appropriate application of the novel EN would be via rapid prototyping based on an individual’s computed tomography scan. This thesis highlights the difficulties associated with limb sparing surgery in veterinary surgery. The currently available procedures provide an alternative for pet-owners that are averse to amputation. However, pet-owners must be aware of the high complication frequencies associated with the techniques. Once refined; the novel EN has potential to decrease implant-related complication rates, however the infection rates are likely to remain high.