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- It is a qualitative defect of osteoclast activity ➔ unable to acidify
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- Type 2 - AD form = most common, Albers-Schonberg Disease (more common)
- Type 1 - AR form = malignant form - short life expectancy. Progressive deafness and blindness
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- 1. Osteoclasts lack ruffled border
- 2. Failure of enzymes – carbonic anhydrase, Chloride channel and proton pump (so cannot acidify howship lacunae)
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- Ceramic - very stiff but brittle
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- Cortical thickening, increased bone density
- Spine - Rugger Jersey spine/ sandwich vertebrae (endplate sclerosis)
- Femur - Erlenmeyer flask ("block femoral metaphysis), Coxa Vara [due to repeted stress fractures], narrow medullary canal
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- Medical treatment - bone marrow transplant, interferon treatment
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- Almost like Pagets
- A - arthritis
- B - blood issues - Anemia - due to reduced bone marrow
- C - cranial nerve, spinal stenosis
- Cranial nerve palsies - overgrowth of skull foramina - Optic nerve > auditory nerve > trigeminal nerve > facial nerve ➔ blind, deaf, facial numbness and weakness
- Spine - spondylosis
- D - deformities - coxa vara due to stress fractures
- P - pathological fractures (brittle)
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- Plates vs IM nailing for fracture femur shaft
- IM nail to span femur, and avoid stress risers
- But stand by multiple sharp reamers.
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- Complex primary
- Pre Op
- Implant choice - cemented in view of osteointegration concerns, hypervascularity makes it difficult for canal prep, may need small DDH stems with hybrid cementless cup
- Address deformities - Templating - patient may have coxa vara deformities
- Equipment stand by
- Instrumentation - use of high speed burrs and sharp drills, stand by few sets as they get blunt easily
- Stand by fracture fixation equipment - femur plates, cerclage wires
- Stand by Fluoroscopy for fracture management
- Stand by long operative time - long list, inform anaesthesia, stand by for blood loss and unpredictability
- Blood management due to anemia - cell saver, hemostasis
- Intraop
- Plan for extensile posterior approach KIV ETO to help create bony cavity for stem has been reported
- Instrumentation - use of high speed burrs and drills instead of broaching to avoid fractures
- Irrigation while drilling - to avoid heat
- Mentally prepared for fractures, especially during final implant impaction - need to be gentle.
- Acetabular side - usually posterior wall. Usually can be managed with supplemental screw fixation
- Femur side - fracture at tip - may require fixation with plate and cerclage wires/ screws
- Post Op
- Scrutinize post op XR - KIV NWB if any suspected fracture