Ch 72 - Musculoskeletal Neoplasia and Limb Sparing Surgery Flashcards
What % of skeletal neoplasia is OSA?
What are the two reported peaks in age of onset?
85%
- Small peak at 18-24m
- Larger peak at 10yr
What are the 2 most common sites of OSA in dogs?
What is the MST with aggressive local and systemis treatment?
Distal radius and proximal humerus
MST 10-12m
What is the accuracy rate of a bone biopsy and of an FNA?
- Bone biopsy 80-90%
- FNA 71% overall, increases to 92% for neoplastic processes
What can be used to increase the diagnostic accuracy of FNA cytology for an OSA?
Staining with ALP
What is the rate of gross metastasis at time of diagnosis of OSA?
What sized thoracic mets can be seen on rads and on CT?
15% gross metastasis
- Nodules 7-9mm in diameter seen on rads
- 1mm seen on CT
When can bone lesions be seen on radiographs?
When there is over 30% bone loss and the lesion is over 2cm
What was the overall rate of bone mets when assessed with rads, nuclear scintigraphy (technetium 99m) and CT scan?
27%
Should not do an amuptation in a dog with bone mets in another limb….
What is the reported MST for dogs with LN mets vs not
- MST with LN mets 59 days vs 318 days
What parameter on biochemistry has been shown to be a negative prognostic indicator?
Elevated ALP
What are some hypothesised causes of fracture-associated OSA and TPLO-associated OSA?
- Comminuted fracture with complicated healing, implant loosening +/- infection
- Implant corrosion (Jonas pins, early TPLO)
- Chronic inflammation
What are the characteristics of a good candidate for a partial scapulectomy?
- Proximal scapula effected
- Has not extended into surrounding soft tissues
- Can be removed with a 2-3cm distal margin with preservation of the shoulder joint
What are the 4 historic classifications of hemipelvectomies?
- Total hemipelvectomy
- Mid to caudal hemipelvectomy
- Mid to cranial hemipelvectomy
- Caudal hemipelvectomy
What can be used to reconstruct an abdominal wall defect after hemipelvectomy?
- The sartorius muscle
- Synthetic mesh
- Medial thigh musculature (gracilus, adductor)
How much of the sacrum can be removed while retaining normal function of contralateral limb?
30%
What are the main options for limb sparing surgery for distal radial OSA?
- Cortical allograft (out of favour)
- Endoprosthesis
- Pasteurised Autograft (65C for 40min)
- Vascularised Ulnar Transposition
- Bone transport osteogenesis (Distraction osteogenesis)
- Irradiated Autograft (not recommended)
- Stereotactic Radiosurgery (high risk of fracture 63%)
Overall complications are very high with post-op infection 40-75% with high risk of recurrence (25%) and implant failure (40%) also concerns
