DefinitionPelvis Osteopetrosis


Inheritable bone disorder characterised by defective osteoclasts

- resulting in hard and brittle bone




Defect of osteoclasts

- unable to acidfy Howship's lacunae

- unable to resorb bone

- missing ruffled border


Heterogenous group

- 60% defect of proton pump

- 5% carbonic anhydrase defect


Inability to remodel bone with thickened sclerotic cortex

- impinges on medulla

- woven bone architecture

- thickened cancellous trabeculae


Unresorbed calcified cartilage

- prone to fracture




1.  Malignant AR


Few survive first decade

- bony overgrowth of medulla

- blocks hematopoiesis

- anaemia/neutropenia/thrombocytopenia

- need bone marrow transplant to survive


Cranial nerve compression

- overgrowth foramina

- optic, auditory, facial n




2.  Intermediate AR


Moderate anaemia

Some nerve compression symptoms

Frequent fractures in first decade


3.  Benign AD 


Most common

- diagnosed after fracture

- 40% asymptomatic

- due to variable penetrance


Clinical Features


1.  Frequent long bone fractures

- femur and tibia


2.  Long bone deformity

- callus slow to organise

- lateral bowing of femur


3.  Hip

- coxa vara


4.  OA

- common in hip

- compression of cartilage on hard bone


Hip Osteopetrosis OA


5.  Spondylosis


6.  Osteomylelitis

- 10 % patients

- most often in mandible

- lack of marrow vascularity

- impairment of white cell function


7.  Cranial nerve compression

- 20-25%

- optic, auditory, trigeminal, facial




Generalised sclerosis

- subchondral sclerosis in pelvis



- bone within bone

- failed resorption of primary spongiosa


Vertebral end plate thickening

- rugger jersey vertebrae


Erlenmeyer flask deformity

- widened club like metaphysis

- in children


Transverse banding of metaphyses




Non operative


1.  Interferon gamma



- increases bone resorption

- improves hematopoiesis and leucocyte function


2.  High dose vitamin D / diet low in calcium



- stimulates osteoclasts


3.  Bone marrow transplant



- children with malignant form


Operative Management




Attempt to treat non operatively if possible

- ORIF difficult

- nil medullary canal

- break drill bits




Plates often fail

- IM load sharing devices best


Increased time to union


Difficulty drilling, inserting screws and pins

- drills over heat and break

- advance 1cm at a time

- frequent cleaning and cooling

- alternate drill bits


Longer surgical time




Technical difficulties


Unable to use hand reamers

- recreate medullary canal

- burrs needed

- use II to check

- short narrow stems

- can consider resurfacing




Increased risk intra-operative fracture


Increased risk infection