Loss of implant-bone interface following distal radial locking-plate endoprosthesis limb-sparing surgery in a dog

An eight-year-old, neutered female Rottweiler was presented with lameness of seven days duration. Radiographs were consistent with a distal radial bone tumour. Limb-sparing surgery was performed using a commercially available endoprosthesis with a locking bone plate. Histopathological examination of the resected bone revealed an intraosseous fibrosarcoma, and postoperative adjuvant chemotherapy was initiated three weeks after surgery. Despite initial satisfactory limb function, lameness worsened four months after surgery. Radiographs revealed large areas of bone lysis around the proximal and distal screws, leading to significant resorption of the radius and radial carpal bone with subsequent construct failure. Further treatment was declined by the owner and the dog was subsequently euthanased. This case illustrates that implant failure is not necessarily averted by the use of locking (compared with non-locking) implants combined with an endoprosthesis to treat distal radial tumours in dogs.     

Biomechanical comparison of cortical radial graft versus ulnar transposition graft limb-sparing techniques for the distal radial site in dogs

OBJECTIVE: To compare the biomechanical properties of radial graft (RG) versus ulnar transposition graft (UTG) limb-sparing techniques in the dog. STUDY DESIGN: Cadaveric study. ANIMALS: Six pairs of normal canine thoracic limbs. METHODS: In each pair of limbs, 1 limb was subjected to the RG technique and the other to the UTG technique. Limbs were tested in axial loading until failure. Modes of failure and biomechanical properties were compared between the 2 groups. Percent coverage of the metacarpal bone by the plate was retrospectively compared between the limbs that failed by fracture of the metacarpal bones and those that did not. RESULTS: RG limbs had significantly greater stiffness, yield load, maximum load, maximum energy, and post-yield energy. All UTG limbs failed by cranial bending of the plate. Half of the RG limbs failed by caudal bending of the plate and half by fracture of the third metacarpal bone at the distal end of the plate. Limbs with <80% plate coverage of the metacarpal bone were significantly more likely to fail by metacarpal fracture. CONCLUSIONS: The RG technique was biomechanically superior to the UTG technique under the conditions studied. At least 80% plate coverage of the metacarpal bone should be achieved. CLINICAL RELEVANCE: Exercise restriction and coaptation bandages should be considered for patients undergoing the UTG technique to minimize potential biomechanical complications.     

Vascularized ulnar bone grafts for limb-sparing surgery for the treatment of distal radial osteosarcoma

The objective of this retrospective study was to compare vascularized free or roll-in ulnar bone grafts for limb-sparing surgery in dogs with radial osteosarcoma with the cortical allograft, metal endoprosthesis, or distraction osteogenesis techniques. Overall, the ulnar graft techniques used in this study demonstrated excellent healing properties. Complications included recurrence of the tumor in 25% (2/8) of the dogs, metastasis in 50% (4/8) of the dogs, implant loosening in 37.5% (3/8) of the dogs, implant failure in 12.5% (1/8) of the dogs, and infection in 62.5% (5/8) of the dogs. Mean survival time was 29.3 mo (range, 9 to 61 mo). The mean metastasis-free interval was 33.67 mo (range, 8 to 54 mo). Tumors recurred locally in two dogs at 10 mo and 20 mo postoperatively. This study yielded similar long-term complications as other limb-sparing options (such as cortical allografts and metal endoprostheses) and allowed dogs to bear weight on the operated limb with acceptable limb function. More research is needed regarding specific healing times for ulnar vascularized grafts, time until implant removal, and the extent of radial bone that could ultimately be replaced by the ulna.     

Ipsilateral vascularised ulnar transposition autograft for limb-sparing surgery of the distal radius in 2 dogs with osteosarcoma

Canine osteosarcoma is the most commonly diagnosed primary bone tumour in the dog, affecting mainly large and giant breed dogs with the predilection site being the metaphysis of long bones, specifically the distal radius, proximal humerus, distal femur and proximal tibia and fibula. Treatment options are either palliative or curative intent therapy, the latter limb amputation or limb-sparing surgery together with chemotherapy. This article describes the use of an ipsilateral vascularised ulnar transposition autograft as well as chemotherapy in 2 dogs with osteosarcoma of the distal radius. Both dogs showed minimal complications with the technique and both survived over 381 days following the surgery. Complications seen were loosening of the screws and osteomyelitis. The procedure was well tolerated with excellent limb use. This technique is indicated for use in cases with small tumour size that have not broken through the bone cortex.     

Proximal radial and distal humeral osteosarcoma in 12 dogs

Twelve dogs were diagnosed with osteosarcoma of the proximal radius or distal humerus from 1990 to 2002, representing 1.0% of all dogs diagnosed with appendicular osteosarcoma. The median body weight (29.8 kg) was significantly less than that of dogs with appendicular osteosarcoma at other sites. Ten dogs were treated with amputation and chemotherapy. These dogs had a metastatic rate of 60%, a median metastasis-free interval of 356 days, and a median survival time of 824 days. There were no significant differences in metastasis-free interval or survival time between dogs with osteosarcoma of the proximal radius or distal humerus and dogs with appendicular osteosarcoma at other sites.     

Use of an ipsilateral vascularized ulnar transposition autograft for limb-sparing surgery of the distal radius in dogs: an anatomic and clinical study

OBJECTIVE: To develop a surgical technique for using the distal aspect of the ulna as a transposition autograft in a distal radial defect and to assess patency of vascular supply and viability of the distal ulna in a heterotopic position. STUDY DESIGN: Cadaveric study and clinical cases. ANIMALS: Twenty-two normal canine thoracic limbs; 3 dogs with distal radial osteosarcoma. METHODS: The arteries and veins of 12 limbs were injected with latex. Barium sulfate suspension was injected into the brachial artery of 10 other limbs after removal of the distal radius only (n = 2), ulna transposition (UT) (n = 6), or no procedure (n = 2). The distal ulna grafts were then harvested and decalcified in formic acid. The grafts were cut into 3-5 mm transverse sections and radiographed with a nonscreen film system to determine filling of intramedullary vessels with barium suspension. UT was performed in 3 dogs with distal radial osteosarcoma. Bone scintigraphy was performed 2-7 days after surgery to assess viability of the transposed ulna graft. RESULTS: Angiography confirmed patency of the caudal interosseous artery in all but 2 limbs in which the UT technique was performed; however, barium-filled vessels were identified in the medullary cavity of all ulnar grafts. Scintigraphy confirmed graft viability in the 3 dogs, all of which had good to excellent limb function. CONCLUSIONS: The distal aspect of the canine ulna can be used as a vascularized transposition autograft to replace distal radial defects, and viability can be maintained. CLINICAL RELEVANCE: The UT technique appears to be an acceptable limb-sparing technique for dogs with tumors of the distal aspect of the radius.     

Limb‐sparing in dogs using patient‐specific,three‐dimensional‐printed endoprosthesis for distal radial osteosarcoma: A pilot study

Limb‐sparing for distal radial osteosarcoma has a high rate of complications. Using personalized three‐dimensional (3D)‐printed implants might improve outcome. The goals of this study were to optimize use of patient‐specific, 3D‐printed endoprostheses for limb‐sparing in dogs in the clinical environment and to report the outcome. This was a pilot study where five client‐owned dogs were enrolled. Computed tomography (CT) of the thoracic limbs was performed, which was used to create patient‐specific endoprostheses and cutting guides, and repeated on the day of surgery. Intra‐arterial (IA) carboplatin was introduced in the clinical management. Limb‐sparing was performed. Outcome measures were time required to produce the endoprosthesis and cutting guide, fit between cutting guide and endoprosthesis with host bones, gait analysis, size of the tumour, percent tumour necrosis, complications, disease‐free interval (DFI) and survival time (ST). Four dogs received IA carboplatin. Excessive tumour growth between planning CT and surgery did not occur in any dog. The interval between the CT and surgery ranged from 14 to 70 days. Fit between the cutting‐guide and endoprosthesis with the host bones was good to excellent. At least one complication occurred in all dogs. Two dogs were euthanized with STs of 192 and 531 days. The other dogs were alive with a follow up of 534 to 575 days. IA chemotherapy is a promising strategy to minimize the risk of excessive tumour growth while waiting for the endoprosthesis and cutting‐guide to be made. The design of the cutting‐guide was critical for best fit of the endoprosthesis with host bones.     

Transverse ulnar bone transport osteogenesis: a new technique for limb salvage for the treatment of distal radial osteosarcoma in dogs

Objective— To develop instrumentation and a technique for transverse ulnar bone transport osteogenesis in dogs.
Study Design— Cadaveric study and in vivo validation (1 dog).
Sample Population— Paired cadaveric antebrachii (n=10 dogs) and 1 live dog.
Methods— Circular fixator constructs were applied and fitted with reeling or linear motors designed to transport an ulnar segment transversely into a defect created by excising the distal 50% of the ipsilateral radius. A longitudinal osteotomy of the adjacent ulna was created and the segment was transported across the radial defect. Pre- and post-distraction CT scans were used to compare the efficacy of each construct. The procedure was performed unilaterally in a live dog using the reeling motor (RM) construct.
Results— Both constructs effectively transported the ulnar segment into the defect. Subjectively, the RMs were easier to apply and operate. No significant differences were observed in the objective measures of efficacy between the 2 construct types. The live dog produced viable regenerate bone after transverse ulnar bone transport.
Conclusions— Transverse ulnar bone transport should be considered a potential method for limb salvage in dogs with osteosarcoma (OSA) of the distal radius. The RMs were effective and clinically applicable.
Clinical Relevance— Transverse ulnar bone transport osteogenesis affords the benefits of longitudinal radial bone transport osteogenesis, allowing resolution of large longitudinal radial defects in a substantially less time as a result of shortening the transport distance. This would be beneficial when treating conditions such as OSA where minimizing convalescence and maximizing quality of life is a priority.     

Alternating carboplatin and doxorubicin as adjunctive chemotherapy to amputation or limb-sparing surgery in the treatment of appendicular osteosarcoma in dogs

Thirty-two dogs with appendicular osteosarcoma treated by amputation or limb sparing had adjuvant chemotherapy of alternating doses of carboplatin (300 mg/m2 IV) and doxorubicin (30 mg/m2 IV) every 21 days for a total of 3 cycles. Efficacy, toxicity, and previously identified prognostic factors for osteosarcoma were evaluated. The median progression free survival was 227 days (range 180-274), and the median overall survival was 320 days (range 153-487). The 1-year survival rate was 48%, and the 2-year survival rate was 18%. Age, sex, surgical procedure, and alkaline phosphatase activity above the reference ranges were not prognostic for survival. There was minimal toxicity associated with the chemotherapy. This protocol could be useful for the adjuvant treatment of appendicular osteosarcoma of dogs.     

Treatment of dogs with osteosarcoma by administration of cisplatin after amputation or limb-sparing surgery: 22 cases (1987-1990).

Twenty-two dogs with appendicular osteosarcoma were treated by amputation (n = 17) or limb-sparing surgery (n = 5). All dogs were given cisplatin (60 mg/m2 of body surface, IV) at 3-week intervals, beginning 1 week after surgery. Number of cisplatin treatments ranged from 1 to 6. Survival data for the 22 dogs were compared with survival data from a historical control group consisting of 162 dogs with appendicular osteosarcoma treated by amputation alone. Median survival time for the 22 dogs given cisplatin was estimated to be 46.4 weeks, and 1- and 2-year survival rates were estimated to be 45.5 and 20.9%, respectively. Survival time was significantly (P less than 0.0001) longer for treated dogs than for control dogs. Statistically significant relation was not found between survival time and number of cisplatin treatments. Three dogs were alive with no evidence of disease at the time of reporting. Of the remaining 19 dogs, 14 (73.4%) were euthanatized for problems documented to be related to metastases. Nine (47.4%) dogs were euthanatized because of bone metastases, and 5 (26.3%) were euthanatized because of pulmonary metastases. The proportion of dogs euthanatized because of bone metastases was significantly (P less than 0.0001) higher for treated than for control dogs. Median survival times for dogs developing bone and lung metastases were estimated to be 51.2 weeks and 21.2 weeks, respectively; however, this difference was not statistically significant. One local tumor recurrence was observed among dogs that had limb-sparing surgery. Significant difference in survival time was not observed between dogs that had limb-sparing surgery and dogs that underwent amputation.     

A comparison of two pamidronate dosing protocols on bone turnover in normal dogs and dogs with osteosarcoma

Introduction: Dogs with appendicular osteosarcoma (OSA) excrete higher concentrations of urine cross‐linked N‐telopeptide of type I collagen (NTx) than normal dogs. NTx is a specific biochemical marker of osteoclastic activity. Pamidronate is a bone‐modulating agent that exerts potent inhibitory effects on osteoclasts. The use of pamidronate is currently being evaluated for the management of osteolytic bone pain in dogs with appendicular osteosarcoma. Despite pamidronate's increasing usage in veterinary oncology, optimal dosing has yet to be determined. Commonly utilized dosages range from 1–2 mg/kg, given intravenously (IV) as a 2‐hour constant rate infusion every 28 days. The purpose of this prospective study was to compare the biological activity of two pamidronate doses (1 mg/kg vs. 2 mg/kg) in the suppression of urine NTx excretion in normal dogs and dogs with appendicular osteosarcoma. Methods: Seventeen OSA dogs receiving single‐agent pamidronate as palliative therapy were evaluated. Group 1A (n = 10) received a dose of 1 mg/kg and group 2A (n = 7) received a dose of 2 mg/kg IV. Urine NTx level were measured at day 0 and 28 using a commercial ELISA (Ostex International). Urine NTx level were also measured in 6 normal dogs: Group 1B (n = 3) received a dose of 1 mg/kg and group 2B (n = 3) received a dose of 2 mg/kg. In normal dogs, urine NTx levels were recorded weekly for six consecutive weeks. Results: In dogs with osteosarcoma, greater reductions in urine NTx excretion from baseline values were demonstrated at 2 mg/kg versus 1 mg/kg (57% and 23%, respectively). Likewise, in normal dogs, urine NTx excretion was suppressed to a greater extent with a dosage of 2 mg/kg versus 1 mg/kg (69% and 23%, respectively). Conclusion: Pamidronate possesses biologic activity in both normal dogs and in dogs with osteosarcoma, as assessed by reductions in urine NTx excretion. Based upon reductions in urine NTx excretion, a dosage of 2 mg/kg appears more effective than 1 mg/kg.     

Retrospective comparison of three locoregional techniques for pelvic limb surgery in dogs

ObjectiveTo retrospectively compare the efficacy and duration of effect of three commonly used locoregional blocks in dogs undergoing pelvic limb orthopaedic surgery.Study designRetrospective clinical study.AnimalsA total of 236 dogs that underwent pelvic limb surgery and were administered a locoregional technique.MethodsA total of 236 hospital records were reviewed and 230 included in statistical analysis. Dogs were grouped as following: electrostimulation-guided pre-iliac femoral and sciatic nerve block (group PFS, n = 70); ultrasound-guided saphenous and sciatic nerve block (group SS, n = 76); or lumbosacral epidural (group EPI, n = 84). In group EPI, bupivacaine 0.5% or ropivacaine 0.75% was used with morphine. Dogs were pain scored (short form of the Glasgow Composite Measure Pain Scale) hourly following recovery from anaesthesia. Analysed data included: time to first postoperative dose of methadone, pain score at that time, intraoperative rescue analgesia, intraoperative hypotension and ability to walk and urinate overnight. Separate analyses were performed including all pelvic limb surgeries and including only elective stifle surgeries. Kruskal–Wallis and Mann–Whitney tests were performed. A p value < 0.05 was considered significant. The median (range) is reported.ResultsFor all pelvic limb surgeries, the time to first postoperative methadone was 530 (110–1337), 440 (140–1030) and 466 (135–1094) minutes in groups EPI, PFS and SS, respectively, and was not significantly different. Postoperatively, 10/84, 15/70 and 12/76 dogs in groups EPI, PFS and SS, respectively, did not require methadone (nonsignificant). Significantly fewer dogs in group EPI (18%) required intraoperative rescue analgesia compared with group SS (38%), but not compared with PFS (30%). Significantly more dogs in group EPI had hypotension intraoperatively (30%) and urinary retention postoperatively (62%).Conclusions and clinical relevanceIntraoperative analgesia may be superior with EPI than SS for some surgeries of the pelvic limb, but not for stifle surgeries. All three techniques provided similar requirement for postoperative analgesia, but EPI caused higher incidence of intraoperative hypotension and postopertive urinary retention.     

A histopathological comparison of two techniques for soft palate resection in normal dogs

Eighteen dogs were used to compare histopathological findings following excision of the soft palate using either a bipolar sealing device or a carbon dioxide laser. Histopathological comparisons were done at 48 and 96 hours after soft palate resection. Mean depths of tissue injury at 96 hours were 3.5 and 3.33 mm for bipolar sealing device and carbon dioxide laser, respectively. Control of hemorrhage was excellent in all dogs, and none of the dogs developed signs of respiratory compromise after soft palate resection. Using the bipolar sealing device for soft palate resection was significantly faster than using the carbon dioxide laser, although both techniques were fast.     

A comparison of two different methods for dead space measurements in ventilated dogs

The aim of the study was to compare two methods of measuring physiological dead space/tidal volume ratio (Vd /Vt ) and alveolar dead space (Vd _ALV). Measurements were obtained by automated single breath CO₂ analysis (Ventrak 1550/Capnoguard 1265 (V&C)) and classical calculations were carried out using the Enghoff–Bohr equation in anaesthetized dogs. The V&C consists of a mainstream capnometer, a pneumotachometer, a signal processor, and computer software to determine continuous single‐breath CO₂ analysis (SBT‐CO₂). Eleven dogs of mixed breed (five female, six male) mean body mass 35 ± 10 kg, aged 9 months to 8 years were studied. Pre‐anaesthetic medication was acepromazine (0.03 mg kg^?1) and methadone (0.1 mg kg^?1). Anaesthesia was induced with propofol given to effect and maintained with propofol (10 mg kg^?1 hour^?1) and fentanyl (0.02 mg kg^?1 hour^?1) by infusion. The dog's trachea were intubated and the carbon dioxide and flow sensor were placed between the tube and the Y‐piece of a circle system (Fi O₂ = 1.0). Controlled ventilation was started (tidal volume 10–15 mL kg^?1) and settings were not changed throughout the measurement period. Mixed expired PCO₂ (P e ?CO₂) was measured by analyzing expired gas collected in a mixing box in the expiratory limb of the circle system. The dorsal pedal artery was cannulated for arterial blood sampling and analysis. Measurements were done every 15 minutes for 1 hour. The Vd /Vt was automatically calculated and displayed from the SBT‐CO₂ analysis and also obtained using the Enghoff modification of the Bohr equation (Vd /Vt = (PaCO₂ ? P e ?CO₂)/PaCO₂). Alveolar dead space was determined by calculating the physiological dead space (Vd phys = expired volume × (Vd /Vt )) and subtracting the anatomical dead space measured by SBT‐CO₂. Values for Vd /Vt and Vd _ALV obtained with both methods were compared using Students t‐test. The mean values from the automatic dead space calculation (Vd /Vt : 0.62–0.63; Vd _ALV: 56.1–64.3 mL) did not differ significantly from those calculated arithmetically (Vd /Vt : 0.62–0.63; Vd _ALV: 54.09–66.31 mL). The mean differences and standard deviation in Vd /Vt was 0.63 ± 0.00 and in Vd _ALV 58.98 ± 4.28 mL for the two measurement techniques. Our data indicate that V&C can be used for accurate noninvasive online Vd /Vt and Vd _ALV measurements in anaesthetized ventilated dogs.     

Pasteurized tumoral autograft and adjuvant chemotherapy for the treatment of canine distal radial osteosarcoma: 13 cases

OBJECTIVE: To report outcome in 13 dogs with distal radial osteosarcoma, without evidence of metastasis, treated by a combination of adjuvant chemotherapy and a pasteurized autograft limb-sparing procedure. STUDY DESIGN: Prospective clinical study. ANIMALS: Thirteen dogs with distal radial osteosarcoma. METHODS: Limb-sparing procedure was performed using an autograft from the excised tumoral segment, pasteurized at 65 degrees C for 40 minutes. Adjuvant chemotherapy (cisplatin or cisplatin and doxorubicin) was administered in all dogs. RESULTS: Mean and median survival times were 531 and 324 days, respectively (range, 180 to 1,868 days). Overall survival was 100% at 6 months, 50% at 12 months, 44% at 18 months, and 22% at 24 months. Lung metastasis occurred in 5 (38%) dogs. Observed complications were local recurrence (2 dogs, 15%), allograft infection (4 dogs, 31%), and implant failure (3 dogs, 23%). Limb function was good in 12 dogs (92%) and fair in 1 dog. CONCLUSIONS: Pasteurized bone autograft derived from the tumoral bone segment was an effective alternative to cortical bone allograft for limb sparing in canine distal radial osteosarcoma, in terms of feasibility, pattern of healing, complications, and survival. CLINICAL RELEVANCE: Use of a pasteurized bone autograft eliminates the need for a canine bone allograft bank and has the added advantage of good fit to the recipient site.