CARPAL ARTHRODESIS WITH EXTERNAL SKELETAL FIXATION IN DOG: 12 CASES

In small animals, arthrodesis is a salvage procedures commonly used to treat muscular, orthopedic and neurologic diseases of carpal joints unresponsive to conventional surgical and medical management. Previously reported techniques include internal fixation using plates applied to either the dorsal, medial, or palmar aspect of the carpus, cross pinning, and linear or circular external skeletal fixation (ESF). The aim of this study was to compare the clinical outcome of carpal arthrodesis obtained by the use of linear ESF and acrylic ESF. A retrospective study was made on the records of the years 2010-2013. Inclusion criteria for pancarpal or radio-carpal arthrodesis were pain and lameness attributable to carpal joints diseases nonresponsive to previous surgical or nonsurgical management, and severe neurological deficiency. Surgical procedure consisted in carpal joints fusion through debridement of cartilage from the articular surfaces, perforation of the subchondral bone plate, cancellous bone transplantation and external skeletal fixation (traditional or acrylic implants). Age, bred, body weight, type of implant and time for ESF removal and were recorded for each dog and groups were compared with Man-Whitney U-test (P<0.05). The sample was composed by 12 patients. Mean duration until ESF removal, based on clinical and radiographic evidence of joint fusion, was 73 days (range 54???86 days): mean time to implant removal was 64.6 days (range 54???70 days) for acrylic ESF and 81.4 days (range 7???86 days) for traditional ESF. Mean time for implant removal is less in patients treated with acrylic ESF, about 8 weeks, than in patients treated with traditional ESF, about 12 weeks. This difference is statistically significant with a P-value of 0.01, and animals with acrylic ESF achieved bone fusion earlier than animals treated with traditional ESF. The best results of the acrylic ESF were probably due to two factors: less incidence of complication (i.e. pin tract infections); and then because the less weight of the implant that is associate to a faster use of the limb. The choice of implant was correlated to body weight, in fact large dogs were treated with traditional ESF. After 4-5 weeks osteolytic areas around the K-wires determinate a reduction of the system working; this condition, associated to a god use of the limb, increases the mechanical loading on the damaged joint and a high response to bone healing and bone matrix deposition. In our experience, ESF arthrodesis demonstrated to be a god option for obtaining carpal bones fusion. This technique offer satisfactory mechanical strength with low trauma to soft tissue during surgery and consequently minor risk of postoperative complications. In small sized dogs the use of acrylic resin is a valid alternative to traditional implants.