summary Hip Osteonecrosis, also known as avascular necrosis of the hip, represents a condition caused by reduced blood flow to the femoral head secondary to a variety of risk factors such as a traumatic event, sickle cell disease, steroid use, alcoholism, autoimmune disorders, and hypercoagulable states. Diagnosis can be made with plain radiographs in moderate/late disease but MRI may be required to detect early or subclinical osteonecrosis. Treatment is generally observation with management of the underlying systemic condition. Operative management is indicated for advanced disease with presence of subchondral collapse, femoral head flattening and/or degenerative joint disease. Epidemiology Incidence 20,000 new cases per year in the United States accounts for 10% of total hip arthroplasties performed Demographics male > females average age at presentation is 35 to 50 Anatomic location bilateral hips involved 80% of the time multifocal osteonecrosis disease in three or more different joints 3% of patients with osteonecrosis have multifocal involvement Risk factors direct causes irradiation trauma hematologic diseases (leukemia, lymphoma) dysbaric disorders (decompression sickness, "the bends") - Caisson disease marrow-replacing diseases (e.g. Gaucher's disease) sickle cell disease indirect causes alcoholism hypercoagulable states steroids (either endogenous or exogenous) systemic lupus erythematosus (SLE) transplant patient virus (CMV, hepatitis, HIV, rubella, rubeola, varicella) protease inhibitors (type of HIV medication) idiopathic Etiology Pathophysiology idiopathic AVN intravascular coagulation is the final common idiopathic pathway pathoanatomic cascade coagulation of the intraosseous microcirculation → venous thrombosis → retrograde arterial occlusion → intraosseous hypertension → decreased blood flow to femoral head → AVN of femoral head → chondral fracture and collapse AVN associated with trauma due to injury of femoral head blood supply (medial femoral circumflex) Associated conditions AVN rates of specific traumatic injuries femoral head fracture: 75-100% basicervical fracture: 50% cervicotrochanteric fracture: 25% hip dislocation: 2-40% (2-10% if reduced within 6 hours of injury) intertrochanteric fracture: rare higher risk of AVN with greater initial displacement and poor reduction decompression of intracapsular hematoma may reduce risk quicker time to reduction may reduce risk Classification Steinberg Classification (modification of Ficat classification) Stage Radiographs MRI 0 Normal Normal MRI and bone scan I Normal Abnormal MRI and/or bone scan II Cystic or sclerosis changes Abnormal MRI and/or bone scan III Crescent sign (subchondral collapse) Abnormal MRI and/or bone scan IV Flattening of femoral head Abnormal MRI and/or bone scan V Narrowing of joint Abnormal MRI and/or bone scan VI Advanced degenerative changes Abnormal MRI and/or bone scan Presentation Symptoms insidious onset of pain pain with stairs, inclines, and impact pain common in anterior hip Physical exam mostly normal initially advanced stages similar to hip OA (limited motion, particularly internal rotation) Imaging Radiographs recommended views AP hip frog-lateral of hip AP and lateral of contralateral hip classification systems based largely on radiographic findings (see below) MRI highest sensitivity (99%) and specificity (99%) double density appearance T1: dark (low intensity band) T2: focal brightness (marrow edema) order when radiographs negative and osteonecrosis still suspected presence of bone marrow edema on MRI is predicitve of worsening pain and future progression of disease Bone scan Treatment Nonoperative bisphosphonates indicated for precollapse AVN (Ficat stages 0-II) trials have shown that alendronate prevents femoral head collapse in osteonecrosis with subchondral lucency However, other studies have also shown no benefit of preventing collapse with bisphosphonates Operative core decompression with or without bone grafting indications for early AVN, before subchondral collapse occurs reversible etiology technique traditional method drill an 8-10 mm hole through the subchondral necrosis alternative method pass a 3.2 mm pin into the lesion two to three times for decompression relieves intraosseous hypertension equals less pain stimulates a healing response via angiogenesis rotational osteotomy indications only for small lesions (<15%) in which the lesion can be rotated away from a weight bearing surface technique typically performed through intertrochanteric region for medial disease perform varus rotational osteotomy for anterolateral disease perform valgus flexion osteotomy outcomes reported success rate of 60% to 90%, mainly in Japan distorts the femoral head making THA more difficult curettage and bone grafting through Mont trapdoor technique or Merle D'Aubigne lightbulb technique indications preferably pre-collapse technique lightbulb - through the cortex of the femoral neck-head junction to access the necrotic area of the femoral head and place bone graft trapdoor - through articular surface vascularized free-fibula transfer indications for both pre-collapse and collapsed AVN in young patient reversible etiology preferred technique remove the necrotic area with large core hole fibular strut is placed under subchondral bone to help prevent collapse or tamp up small areas of collapse outcomes some centers demonstrating 80% success at 5 to 10-year follow-up less predictable in patients >40 complications related to donor site morbidity sensory deficit motor weakness FHL contracture tibial stress fracture from side graft is taken total hip replacement indications younger patient with crescent sign or more advanced femoral head collapse, +/- acetabular DJD irreversible etiology (chronic steroid use) patients >40 with large lesions techniques cementless cup and stem care must be taken while preparing the femur as there are high rates of femoral canal perforation outcomes in young patients with osteonecrosis, there is a higher rate of linear wear of the polyethylene liner and a higher rate of osteolysis than compared to older patients who have THA for osteoarthritis provides good pain relief and function most reliable means to provide pain relief and immediate return of function total hip resurfacing indications in advanced DJD with small, isolated focus of AVN requires adequate bone to support resurfacing component contraindicated in underlying disease process or chronic steroid use causing AVN (poor bone quality) and renal disease (metal ions from metal-on-metal implant) outcomes medium-term follow-up showing problems with acetabular erosion and pain hip arthrodesis indications only consider in the very young patient in a labor intensive occupation Prognosis Risk of femoral head collapse with osteonecrosis is based on the modified Kerboul combined necrotic angle calculated by adding the arc of the femoral head necrosis on a mid-sagittal and mid-coronal MR image Low-risk group = combined necrotic angle less than 190° Moderate-risk group = combined necrotic angle between 190° and 240° High-risk group = combined necrotic angle of more than 240°
QUESTIONS 1 of 20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Previous Next Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ13.50) Which of the following is the most common intraoperative complication in a patient with sickle cell disease undergoing a total hip arthroplasty? QID: 4685 Type & Select Correct Answer 1 Periprosthetic fracture distal to the implant 11% (652/5908) 2 Iatrogenic fracture causing pelvic discontinuity 4% (241/5908) 3 Perforation of the femoral canal 61% (3615/5908) 4 Cardiac arrest from fat embolization to lungs 16% (922/5908) 5 Injury to the sciatic nerve 8% (444/5908) L 1 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 3 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ12.254) A 45-year-old with a history of sickle cell anemia reports hip pain for the past 6 months. A radiograph of the affected hip is shown in Figure A. Which of the following interventions has been shown to have the best outcomes in this patient population? QID: 4614 FIGURES: A Type & Select Correct Answer 1 Observation 1% (42/4204) 2 Bisphosphonates 2% (73/4204) 3 Hemi-arthroplasty 3% (128/4204) 4 Uncemented metal on polyethylene total hip arthroplasty 76% (3197/4204) 5 Cemented metal on polyethylene total hip arthroplasty 17% (735/4204) L 2 Question Complexity B Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic (OBQ12.270) A 65-year-old patient was treated with an open reduction/internal fixation for a left femoral neck fracture sustained 25 years ago. Five years ago he developed hip pain and was converted to a left hip hemiarthroplasty. He presents with complaints of groin pain for the past 6 weeks. A recent radiograph is shown in Figure A. The patient’s physical exam is limited secondary to pain. Serum laboratory values are WBC-8.0, ESR-20, CRP-0.5. A synovial fluid aspirate of the hip demonstrates < 500 cells (60% PMN). What is the most likely cause of this patient's symptoms? QID: 4630 FIGURES: A Type & Select Correct Answer 1 Acetabular protrusio 93% (5709/6162) 2 Infected hip hemiarthroplasty 1% (55/6162) 3 Lumbar radiculopathy 0% (19/6162) 4 Impingement of the hip hemiarthroplasty 5% (312/6162) 5 Iliopsoas tendinitis 1% (37/6162) L 1 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 1 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ11.196) A 47-year-old man presents with 1 week of left leg pain. 6 months prior he underwent a vascularized free-fibula bone graft from his left leg to his right hip for avascular necrosis. The pain is located at the level of his donor site and is worse with weight-bearing and relieved by rest. Physical exam shows focal tenderness over his tibia. A lateral radiograph from the day of presentation is shown in Figure A. WBC, ESR, and CRP are all within normal limits. What is the next best step in management to confirm the diagnosis? QID: 3619 FIGURES: A Type & Select Correct Answer 1 Compartment pressure measurements 4% (134/3161) 2 CT scan 11% (338/3161) 3 MRI scan 81% (2567/3161) 4 Ultrasound to rule out deep abscess 3% (89/3161) 5 Bone biopsy 1% (17/3161) L 2 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 3 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ09.8) In patients with sickle cell disease and asymptomatic osteonecrosis of the femoral head identified with magnetic resonance imaging, what percentage will eventually go on to femoral head collapse? QID: 2821 Type & Select Correct Answer 1 < 10% 4% (116/2848) 2 11% to 25% 19% (552/2848) 3 26 to 50% 17% (473/2848) 4 51 to 75% 15% (419/2848) 5 > 75% 45% (1268/2848) L 4 Question Complexity D Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 5 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ08.239) A 40-year-old man complains of increasing groin pain. Radiographs show femoral head avascular necrosis with subchondral lucency but without femoral head collapse. Which of the following medical treatments have been shown to decrease the risk of subsequent femoral head collapse? QID: 625 Type & Select Correct Answer 1 Cyclic parathyroid hormone therapy 8% (188/2340) 2 Bisphosphonate therapy 86% (2024/2340) 3 RANK ligand therapy 4% (82/2340) 4 RANK therapy 0% (7/2340) 5 Selective estrogen receptor modulator therapy 1% (22/2340) L 1 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK This is an AAOS Self Assessment Exam (SAE) question. Orthobullets was not involved in the editorial process and does not have the ability to alter the question. If you prefer to hide SAE questions, simply turn them off in your Learning Goals. (SAE07HK.100) Osteonecrosis of the large joints may develop in patients with which of the following conditions? QID: 6060 Type & Select Correct Answer 1 Collagen I disease 4% (19/535) 2 Antiphospholipid syndrome (APS) 68% (366/535) 3 Hemochromatosis 20% (106/535) 4 Achondroplasia 3% (16/535) 5 Paget’s disease 5% (27/535) L 3 Question Complexity E Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 Review Tested Concept Review Full Topic This is an AAOS Self Assessment Exam (SAE) question. Orthobullets was not involved in the editorial process and does not have the ability to alter the question. If you prefer to hide SAE questions, simply turn them off in your Learning Goals. (SAE07HK.53) A 30-year-old patient has had severe left hip pain and difficulty ambulating, necessitating the use of a cane, for the past 6 months. A photomicrograph of the femoral head sectioned at the time of surgery is shown in Figure 31. What is the most likely diagnosis? QID: 6013 FIGURES: A Type & Select Correct Answer 1 Renal osteodystrophy 4% (18/466) 2 Pyogenic osteomyelitis 2% (7/466) 3 Osteoarthritis 2% (7/466) 4 Osteonecrosis 91% (423/466) 5 Tuberculosis osteomyelitis 2% (10/466) L 1 Question Complexity E Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic This is an AAOS Self Assessment Exam (SAE) question. Orthobullets was not involved in the editorial process and does not have the ability to alter the question. If you prefer to hide SAE questions, simply turn them off in your Learning Goals. (SAE07HK.51) Figure 30 shows the MRI scan of a 68-year-old woman who has left hip pain. What is the most appropriate treatment? QID: 6011 FIGURES: A Type & Select Correct Answer 1 Open reduction and internal fixation 1% (4/632) 2 Total hip arthroplasty 96% (604/632) 3 Incisional biopsy 3% (21/632) 4 Proximal femoral resection and reconstruction 0% (2/632) 5 Arthrodesis 0% (0/632) L 1 Question Complexity E Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 Review Tested Concept Review Full Topic (OBQ04.220) A 41-year-old male has steroid-induced avascular necrosis of the hip and decides to undergo metal on polyethylene total hip arthroplasty. His 80-year-old, sedentary father had a total hip replacement 5 years ago. With comparison to his father, the patient should be informed of the following risk? QID: 1325 Type & Select Correct Answer 1 Increased risk of sciatic nerve palsy 2% (73/3585) 2 Increased longevity of prothesis 2% (81/3585) 3 Increased risk for polyethylene wear and osteolysis 94% (3368/3585) 4 Reduced range of motion 1% (23/3585) 5 Lower likelihood of revision surgery 1% (23/3585) L 2 Question Complexity D Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 3 Review Tested Concept Review Full Topic
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