Orthopedic Surgery and Pall Care

Question 1

Common locations of bone metastases

Answer 1

• axial most common
• appendicular skeleton - femur
• less common distally

Question 2

Evaluation of a patient with bony mets

Answer 2

• Known primary thought to be in remission/disease free
  
  • CT CAP
  • bone scan
  • biopsy if accessible to confirm recurrence
• Unknown primary and bony lesion
  
  • CTCAP
  • bone scan
  • biopsy if possible
• Widely disseminated mets with known diagnosis
  
  • biopsy unneccessary
  • imaging for location

Question 3

Imaging

Answer 3

• Xray for extremity lesions, then CT, MR
• significant back pain –> MR or PET
• PET for comprehensive whole body cancer staging, rapidly progressive mets, Ewing sarcoma
• MM - lytic lesions can be negative on bone scan. Skeletal survery Xray

Question 4

Xrays

Answer 4

• minimum 1 cm lesion
• bone mineral loss > 50%
• to detect on Xray
• useful for overall structural integrity

Question 5

Bone scan

Answer 5

• useful to ID all bone lesions in skeleton
• false negative with MM (because no new bone deposition)
• false negative with rapidly progressive mets (lung, melanoma)
• sensitivity 75%, poor specificity

Question 6

CT Scan

Answer 6

• useful for structural integrity
• helpful for pre op planning
• occult fractures
• can see soft tissue extension

Question 7

MRI

Answer 7

• excellent contrast between normal bone marrow and tumour marrow
• cannot provide info about structural integrity
• MRI spine

Question 8

PET

Answer 8

• tracer show uptake in cells with high metabolic acitivity
• likely helpful for bony disease, but high cost

Question 9

Surgery for bony metastatic disease : goals

Answer 9

• QOL
• immediate WBAT
• quickest return to function
• pain control

Question 10

Indications general for ortho surgery in pall care

Answer 10

• mechanical stabilization
• impending path #
• path #

Question 11

Assessing path fracture risk

Answer 11

• scoring system : Mirel’s insufficient
• best evidence for:
  
  • prognosis > 6 months

Question 12

Bone Pathophysiology

Answer 12

Lytic lesions

• cytokines from tumour cells stimulate osteoclast activity
• osteoclasts resobr organic components of bone and release calcium from calcium hydroxyapatite into circulation
• greater removal of mineral/organiz components
• greater loss in strength, more likely to fracture

Blastic lesions

• do not disturb mineral content of bone but disrupt normal trabeular framework of cancellous bone
• lower likelihood fracture

Question 13

Location of skeletal mets

Answer 13

• Lower extrem lesions
  
  • weight bearing most likely to fracture
• Upper extrem
  
  • humerous from loading /transferring

Question 14

How does bone fracture from metastatic disease occur?

Answer 14

1. Stress risers from smaller osteolytic defect in cortex
   * multiple stresses are concentrated around a small hole
2. Torsional stress

• torsional strength of bone more reduced that compressive or bending
• torsional load from ADLS - pivoting, turning from standing position

Question 15

Orthopedic surgical interventions : tumour excision

Answer 15

• intralesional excision
• marginal/wide excision

Question 16

Ortho surgical interventions : prosthetic joint replacement

Answer 16

• Knee, hip, shoulder, elbows
• fractures involving epiphyseal surface into joint

Question 17

Ortho surgical interventions : plate fixation

Answer 17

• goal of using plates is to provide load bearing stability to fracture site until healing occurs
• unlikely in path #
• risk of screw and plate breakage
• useful if healing quick or radiosensitive tumour
• does not allow weight bearing immediately post op

Question 18

Ortho interventions: intramedullary nail fixation

Answer 18

• rod or ball down centre of medullar cavity
• load bearing device
• fracture less likely as device in centre of bone
• diaphyseal fractures
• augmented with cement

Question 19

Ortho interventions : bone cement

Answer 19

• useful adjuvant
• full defects after excision
• barium contrast in cement to facilitate xrays
• emits heat –> destroys tumour cells

Question 20

Ortho intervention : amputation

Answer 20

• limited role
• limb that cannot be recontructed due to extensive disease
• no other options
• fungating masses, recurrent uncontrolled infections
• intractable pain

Question 21

Epiphyseal fractures (rounded end portion long bones that articulate)

Answer 21

• end of long bones involving articular surface
• poor healing
• poor stabilization
• Cemented arthroplasty

Question 22

Metaphyseal fractures (neck of long bone, growth plate in children)

Answer 22

• IM fixation difficult
• plate fixation
• arthroplasty

Question 23

Diaphyseal fractures (shaft)

Answer 23

• IM nails
• bone cement

Question 24

Pelvic and acetabular fractures

Answer 24

• THA
• Saddle prosthesis - high risk of complications

Question 25

Kyphoplasty

Answer 25

• Balloon into vertebral body and inflated
• creates space for injected cement
• contraindications : neuro compromise or evidence of SCC
• advantages:
  
  • restores biomechanics
  • lowered risk of cement extrusion
  • pain relief
• complications
  
  • cement leak - epidural space
  • chemothermal damage to cord
  • cement embolism

Question 26

Vertebroplasty

Answer 26

• percutaneous injection of cement to re-expand collapsed vertebra
• avoid in SCC or sig neuro findings
• Complications
  
  • cement leak higher risk than kyphoplasty
  • chemothermal damage to cord
  • cement embolism

Question 27

Radiofrequency ablation of bony mets

Answer 27

• alternating electrical current to cause thermal necrosis of cancerous tissue
• useful for tumours> 5 cm
• alternative to surgical for small extremity lesions
• useful for flat bones of pelvis
• Complications:
  
  • skin necrosis
  • damage to health tissue
  • fracture
• Contrindications:
  
  • impending path fracture

Question 28

Embolization of bony mets

Answer 28

• useful for vascular tumours that metastasize to bone (renal, thyroid)
• risk of hemorrhage in surgery

Question 29

Osteoplasty

Answer 29

• injection of bone cement into painful pelvic lytic lesion
• alternative to surgery, radiation if CI
• improves strength, mobility, pain
• CI:
  
  • local infection
  • coagulopathy
• complications
  
  • intraarticular injection accidentally