Analysis of outcome in dogs that undergo secondary amputation as an end‐point for managing complications related to limb salvage surgery for treatment of appendicular osteosarcoma

Abstract

Appendicular osteosarcoma (OSA) remains a prevalent musculoskeletal cancer in dogs and definitive local control followed by adjuvant cytotoxic chemotherapy is considered the gold standard approach. Several studies support surgical limb salvage as a means of local control with similar outcomes compared with limb amputation. Complications are well described for limb salvage but little is known of dogs that undergo secondary amputation as a result of complications and outcomes specific to this group. A retrospective analysis of dogs in an institutional primary bone tumour registry was performed to identify dogs diagnosed with histologically confirmed OSA treated with surgical limb salvage with a technique that required an implant to reconstruct the osseous defect. A total of 192 dogs were identified with 31 dogs undergoing secondary amputation representing a limb preservation rate of 84%. A total of 111 dogs were analysed: 31 secondary amputation cases and 80 controls were selected for comparison. The most common reasons for secondary amputation were local recurrence (LR) and surgical site infection (SSI), with odds ratios of 3.6 and 1.7, respectively. Dogs that underwent secondary amputation had a significantly (P = .05) longer median disease specific survival time (ST) (604 days) compared with the control group (385 days). Dogs lived for a median of 205 days beyond secondary amputation and 97% had good functional outcome. Significant independent factors that positively influenced ST were secondary amputation, moderate SSI, severe SSI and age.

Outcome and prognosis for canine appendicular osteosarcoma treated with stereotactic body radiation therapy in 123 dogs

“…The remaining 32 patients elected for euthanasia after being diagnosed with a pathologic fracture, leading to the shorter survival time. Improved survival following amputation is a similar finding to a recent publication using a limb salvage surgical procedure as the initial primary treatment 2 …”

“…In these cases, a limb‐sparing treatment provides an alternative to amputation. Limb sparing surgery allows for resection of the tumour with the goal of maintaining a functional limb; however, complication rates following these surgeries range from 50% to 96% 2‐6 . Surgical options are limited to the distal radius, ulna, and diaphyseal lesions with poor results reported for limb sparing surgery for the humerus 7 .…”

Post‐operative complications following apocrine gland anal sac adenocarcinoma resection in dogs

“…This approach was adopted in a study of risk factors for secondary amputation following limb salvage surgery for osteosarcoma in dogs but failed to find an association between R-classification and LR. 18 The difference though may be one of tumour biology where the mode of metastasis in AGASACA is primarily lymphatic while primarily hematogenous in bone sarcoma. This warrants further study and the inclusion of blood vessel or lymphatic invasion into the adequacy of histologic margin should be considered in AGASACA.…”

Fracture rate and time to fracture in dogs with appendicular osteosarcoma receiving finely fractionated compared to coarsely fractionated radiation therapy: A single institution study

“…This may also reflect clinician selection bias unlikely to recommend amputation for patients with more advanced disease. A recent study reported a median survival of 205 days following secondary amputation following limb‐spare complications so it is not unreasonable to apply similar reasoning to secondary amputation following RT (Wustefeld‐Janssens et al., 2020). Additional factors evaluated against patient survival are summarised in Table 4.…”