CC Nov 2014 Avascular necrosis of the hip

echoecho's version from 2015-06-30 18:34


Question Answer
Another term for avascular necrosis (AVN)?osteonecrosis
Define AVN?this develops when blood flow to the subchondral bone is impaired resulting in death of osteocytes and osteoblasts. This cellular death then leads to increased osteoclastic activity, overall bone loss and collapse of the overlying articular surface
This impairment of blood flow to the femoral head resulting in AVN can be caused by what factors?1) previous trauma to the hip 2) long-term corticosteroid use 3) smoking 4) chronic alcohol use 5) coagulopathy 6) childhood hx of slipped capital femoral epiphysis 7) vasculitis 8) HIV 9) hyperlipidemia 10) sickle cell disease 11) post-organ transplantation
Children have an idiopathic form of AVN called?Legg-Calve-Perthes disease
Decade this presents in?4th and 5th decade of life
Presentation?1) progressive hx of nontraumatic hip pain 2) pain usually in the groin but may be in the buttock or thigh 3) 1/3 of pts have nocturnal pain 4) 2/3 of patients have pain at rest 5) ROM limitation on forced internal rotation and abduction 6) presence of limp is a late finding 7) small % of pts are asymptomatic with the incidental finding of AVN
Initial diagnostic testing? Results in early stages?plain x-ray of hip (AP, lateral, and lateral frog-leg) which will normal in early stages
What is seen on x-ray in later stages?cyst formation and sclerosis
What is seen on x-ray in more advanced stages?femoral head flattening or subchondral collapse
***What is considere the imaging test of choice after plain x-rays have bene obtained if the x-rays are suspicious for, but not definitive of AVN or if the x-rays are normal but AVN is suspected clinically?MRI w/o contrast
***Why is MRI better than x-ray films?MRI can detect early stages of osteonecrosis BEFORE plain films are abnormal and can help to determine the extent of the disease when x-rays show advanced disease
***What imaging study can be considered in pts where MRI can't be performed? How does this imaging study compare to MRI?1) Tc-99m bone scan with single-photon-emission CT (SPECT) of the hips 2) bone scan is less sensitive than MRI
*** How does CT scan compare to MRI or bone scans?less sensitive than both MRI and bone scans
*** Comment on using US and laparoscopic visualization for dxnot recommended in routine evaluation of AVN of the femoral head
What imaging study is the basis for 2 avascular necrosis classification systems (Steinberg or Univ of Penn and the Association Research Circulation Osseous)? These systems are used to quantify what?1) MRI 2) the degree of cellular damage based on a staging system (stage 1 normal, stage IV or greater meaning advanced disease) and provide a basis for clinical management
Management option for AVN before articular collapse? How is this option augmented?Core decompression of necrotic bone (best means of preventing disease progression). Augmented by placement of a vascularized fibular graft
Studies that incoporate concentrated ___ ____ in the augmentation material have early, but promising, results at reduction of femoral head collapse and subsequent need for arthroplaty?stem cells
List nonoperative interventions that may improve symptoms?smoking cessation, alcohol cessation, limiting weight bearing (though cruthes or a can do not appear to slow progression of disease in the presence of underyling necrosis)
Comment on bisphosphonates and statins and hyperbaric oxygen therapy for AVN?inconclusive results
What is the treatment of choice in presence of advanced disease (articular collapse, arthritic change)?hip replacement
In younger patients, why is hip replacement deferred?defer as long as possible due to the fact replacement hardward may last only 15-20 years, requiring another replacement at a future date
What may obviate the need for hip replacement sooner than later?intractable pain and limitations