Osteonecrosis

BASICS

Cellular bone death due to vascular insufficiency
- Can be either traumatic (most common) or nontraumatic
Also known as:
- Avascular necrosis (AVN)
- Ischemic necrosis
- Idiopathic osteonecrosis
- Lunatomalacia/Kienb ¶ck disease (lunate bone)
- Subchondral fracture
- Aseptic necrosis
- Legg-Calve-Perthes syndrome (idiopathic necrosis of the femoral head in children)
- Osteonecrosis of the jaw (ONJ)

DESCRIPTION

Primarily involves the epiphysis of long bones (most commonly femoral head, humeral head, and the femoral condyles), but any bone may be affected
System(s) affected: musculoskeletal

EPIDEMIOLOGY

Predominant age: 3rd to 5th decades
Predominant sex: varies depending on comorbidities and etiology

Incidence

10,000 to 20,000 new cases per year in the United States (1)
Osteonecrosis is the most common cause for total hip replacement in young adults. It represents about 10% of all hip replacements (1).
Disease is bilateral in at least 50% of all nontraumatic cases and in 75 " 95% of cases associated with steroid use (1).

Prevalence

Hip: occurs in 10% of undisplaced femoral neck fractures, 15 " 30% of displaced femoral neck fractures, and 10% of hip dislocations
Jaw: Over the past 10 years, ONJ has been reported in 5% of cancer patients receiving high-dose IV bisphosphonates.
Glucocorticoid-induced osteonecrosis develops in 9 " 40% of patients on long-term therapy.
Osteonecrosis occurs during early postoperative period in 20 " 25% of patients after renal transplant.

ETIOLOGY AND PATHOPHYSIOLOGY

Pathophysiology is multifactorial and not fully understood. The final common pathway is the interruption of blood flow to the bone.
Vascular insufficiency leads to demineralization, trabecular thinning, subchondral plate fracture, and fatigue/fracture of the necrotic segment (1).
Traumatic: disruption of blood supply due to vessel injury as the result of fracture or dislocation
Nontraumatic
- Impedance of blood flow due to vascular compression/vasospasm
- Extraluminal obliteration from marrow edema
- Intraluminal obstruction from thromboembolism, nitrogen bubbles (diving), fat emboli, intravascular coagulation, or vascular stasis (1)

RISK FACTORS

Primary risk factors are a history of trauma, prolonged corticosteroid use, or alcoholism.
Other risk factors include bisphosphonate use, sickle cell disease, diabetes mellitus, hyperlipidemia, oral contraceptives, pregnancy, chemotherapy, decompression sickness ( "bends " ; "Caisson disease " ), chronic pancreatitis, Crohn disease, gout, myeloproliferative disorders, radiation treatment, rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), chronic renal failure and hemodialysis, chronic liver disease, Gaucher disease, organ transplant, trauma, tobacco use, HIV, hypercoagulable states, fat embolus syndrome, developmental hip dysplasia, and slipped capital femoral epiphysis (SCFE).

GENERAL PREVENTION

Limit alcohol use. There is a dose-dependent relationship with alcohol consumption. The relative risk (RR) is 3.3 for <400 mL/week and 17.9 for >1,000 mL/week.
Smoking cessation: Smokers have RR of 3.9 versus nonsmokers.
Limit corticosteroid use: Serum corticosteroid concentration is cumulatively associated with osteonecrosis.
Consider screening bone density for high-risk patients.
Consider preventive dental checkup before high-dose bisphosphonate use in chemotherapy patients.

DIAGNOSIS

HISTORY

Consider osteonecrosis in individuals presenting with bone pain who have a history of trauma or other risk factors.

Hip/femoral head: dull, aching groin/hip pain that is progressive and worsens with weight bearing
Knee: dull, aching knee pain that worsens with weight bearing, stair climbing, and at night
Humeral head: shoulder pain that is severe and poorly localized, worsens at night, and with activity
Lunate (Kienb ¶ck disease): pain and stiffness of dorsal wrist of dominant hand
Jaw: exposed bone in the mouth that fails to heal despite appropriate intervention

PHYSICAL EXAM

Hip/femoral head
- Decreased and painful hip range of motion, especially in rotation and abduction
- Antalgic or Trendelenburg gait
Knee
- Pseudolocking secondary to pain, effusion, or muscle contracture
Humeral head
- Active motion inhibited by pain
- Passive motion and strength preserved
Lunate
- Dorsal swelling with tenderness over radiocarpal joint
- Restricted and painful dorsiflexion of wrist with weakness of grip

DIFFERENTIAL DIAGNOSIS

Hip/femoral head
- Osteoarthritis (OA), femoral neck fracture, labral tear, osteomyelitis, muscle strain, transient synovitis, bone marrow edema syndrome
Knee
- OA, septic arthritis, meniscal tear, bone bruise, transient osteopenia of the knee, pes anserine bursitis, osteochondritis desiccans
Humeral head
- Adhesive capsulitis, rotator cuff tear/tendonitis, osteomyelitis
Lunate (Kienb ¶ck disease)
- TFCC injury, tenosynovitis of extensor compartments, RA, degenerative joint disease, occult ganglion, other carpal bone injury

DIAGNOSTIC TESTS & INTERPRETATION

No specific physical findings or laboratory tests reliably establish the diagnosis
Clinically suspected osteonecrosis can be confirmed only by diagnostic imaging or biopsy.

Initial Tests (lab, imaging)
Consider testing for sickle cell disease (Hb electrophoresis), hyperlipidemia (fasting lipid profile), and coagulopathies (protein C, protein S, factor V Leiden) with atraumatic etiology.

Plain radiographs (first line)
- Early stages: unremarkable
- Mild to moderate AVN: mild bone density changes followed by sclerosis, cyst formation
- Advanced disease: bony deformities and loss of contours, subchondral lucency (crescent sign), and osseus collapse
- Specific views based on location
  - Hip/femoral head: anteroposterior (AP) and frog-leg lateral views of both hips
  - Knee: AP, lateral, and tunnel view of knee
  - Humeral head: AP, true AP, and axillary views of shoulder
  - Lunate: standard wrist films
MRI without contrast: Gold standard for diagnosis (sensitivity and specificity >98%); obtain if x-ray findings are normal and clinical suspicion is high:
- Early stages: decreased signal intensity of the subchondral region on both T1- and T2-weighted images (water signal)
- Mild to moderate: high signal intensity line within two parallel rims of decreased signal intensity on T2-weighted scans (double-line sign)
- Advanced: deformity and calcification of the articular surface
  - Bone marrow edema on MRI is a marker of disease progression and elevated risk for collapse of the femoral head.
Bone scan: single-photon emission computed tomography (SPECT):
- Central area of decreased uptake surrounded by an area of increased uptake (doughnut sign)
- Not as sensitive as MRI
Staging: Several different staging systems are available for the femoral head (2).
Original Ficat-Artlet classification based on radiographic findings.
ARCO Classification (3)[C]
- Stage 0: normal diagnostic testing
- Stage 1: X-rays are normal. Positive MRI and biopsy.
- Stage 2: X-rays may show osteopenia, sclerosis, or subchondral cysts but no collapse.
- Stage 3: X-rays will show a subchondral radiolucent fracture line (crescent line). Flattening of the femoral head may also be present.
- Stage 4 (end-stage): X-rays will show joint space narrowing and other degenerative changes similar to osteoarthritis.
Steinberg stages 0 to 6 are based on imaging and subdivided into categories based on percentage of the femoral head affected. They are a modification of the Ficat-Arlet stages based on imaging studies (4)[B].

TREATMENT

Early diagnosis is important.
Treatment depends on the age, location, stage of the disease, and overall health of the patient.
The goal of therapy is to preserve the native joint.

GENERAL MEASURES

Usually managed as an outpatient. Inpatient care if surgery indicated.
Crutches or other assistive devices to avoid weight bearing (if weight-bearing joint is affected)

MEDICATION

No medical treatment has been proven effective for arresting the disease process.
NSAIDs and other analgesics, as needed, for pain relief
Prophylactic alendronate may help prevent collapse of femoral head; lipid-lowering agents help prevent steroid-induced osteonecrosis (5)[B].

ISSUES FOR REFERRAL

Refer to orthopedics for surgical opinion.

SURGERY/OTHER PROCEDURES

Surgical options are controversial and depend on severity and site of disease. Joint-preseving procedures are preferred when possible. Severe disease may require total joint replacement.
Hip/femoral head:
- Early stages (precollapse) treated surgically with bone decompression and possible bone graft
- Later stages (postcollapse) treated with total hip arthroplasty
Knee: arthroscopy, osteochondral grafts, high tibial osteotomy, core decompression, unicompartmental/total knee arthroplasty
Humeral head: arthroscopy, core decompression, hemiarthroplasty, total shoulder arthroplasty
Lunate (Kienb ¶ck disease): lunate excision with/without replacement, joint-leveling procedures, intercarpal fusions, revascularization, salvage procedures

COMPLEMENTARY & ALTERNATIVE MEDICINE

Noninvasive modalities including electrical stimulation, shock wave therapy, electromagnetic field therapy and hyperbaric oxygen are undergoing trials. Some studies show improvement in pain, function, or outcomes, but evidence remains limited.

ONGOING CARE

Physical therapy and occupational therapy as adjuncts

PATIENT EDUCATION

Physicians prescribing bisphosphonates should alert patients to potential oral complications, and advise patients to notify their oral health provider that they are taking these drugs.
Patients at high-risk for osteonecrosis should be educated about typical symptoms, and advised to present early for care should any symptoms develop.

PROGNOSIS

Poor prognostic factors include age >50 years, advanced disease at time of diagnosis, necrosis of >1/3 of the femoral head weight-bearing area, lateral femoral head involvement, and the presence of nonmodifiable risk factors.
Progression of asymptomatic osteonecrosis of the femoral head is proportional to lesion size. Small lesions (<15% involvement) are unlikely to progress while large lesions (>30% involvement) are much more likely to progress.
>50% of patients with osteonecrosis require surgical treatment within 3 years of diagnosis.

COMPLICATIONS

Surgical complications include nonunion, malunion, peroneal nerve palsy, deep venous thrombosis, intraoperative fracture, and postoperative dislocation.
Progression of disease can also lead to OA of the involved joint (6).

REFERENCES

11 Lafforgue P. Pathophysiology and natural history of avascular necrosis of bone. Joint Bone Spine. 2006;73(5):500 " 507.22 Kaushik AP, Das A, Cui Q. Osteonecrosis of the femoral head: an update in year 2012. World J Orthop. 2012;3(5):49 " 57.33 Gardeniers JWM. Report of the Committee of Staging and Nomenclature. ARCO Newsletter. 1993;5(2):79 " 82.44 Steinberg ME, Hayken GD, Steinberg DR. A quantitative system for staging avascular necrosis. J Bone Joint Surg Br. 1995;77(1):34 " 41.55 Lai KA, Shen WJ, Yang CY, et al. The use of alendronate to prevent early collapse of the femoral head in patients with nontraumatic osteonecrosis. A randomized clinical study. J Bone Joint Surg Am. 2005;87(10):2155 " 2159.66 Mankin HJ. Nontraumatic necrosis of bone (osteonecrosis). N Engl J Med. 1992:326(22):1473 " 1478.

ADDITIONAL READING

American College of Radiology. (ACR) Appropriateness Criteria for avascular necrosis of the hip. National Guideline Clearinghouse. 2010;31:15734.
Chadha GK, Ahmadieh A, Kumar S, et al. Osseointegration of dental implants and osteonecrosis of the jaw in patients treated with bisphosphonate therapy: a systematic review. J Oral Implantol. 2013;39(4):510 " 520.
Mont MA, Hungerford DS. Non-traumatic avascular necrosis of the femoral head. J Bone Joint Surg Am. 1995;77(3):459 " 474.
National Institute of Arthritis and Musculoskeletal and Skin Diseases. Osteonecrosis. www.niams.nih.gov/health_info/osteonecrosis/. Accessed 2014.
Reid IR, Cornish J. Epidemiology and pathogenesis of osteonecrosis of the jaw. Nat Rev Rheumatol. 2011;8(2):90 " 96.

CODES

ICD10

M87.9 Osteonecrosis, unspecified
M87.20 Osteonecrosis due to previous trauma, unspecified bone
M87.00 Idiopathic aseptic necrosis of unspecified bone
M87.059 Idiopathic aseptic necrosis of unspecified femur
M87.09 Idiopathic aseptic necrosis of bone, multiple sites
M87.10 Osteonecrosis due to drugs, unspecified bone
M87.159 Osteonecrosis due to drugs, unspecified femur
M87.188 Osteonecrosis due to drugs, other site
M87.19 Osteonecrosis due to drugs, multiple sites
M87.256 Osteonecrosis due to previous trauma, unspecified femur
M87.28 Osteonecrosis due to previous trauma, other site
M87.29 Osteonecrosis due to previous trauma, multiple sites
M87.3 Other secondary osteonecrosis
M87.88 Other osteonecrosis, other site
M87.89 Other osteonecrosis, multiple sites
M87.08 Idiopathic aseptic necrosis of bone, other site

ICD9

733.40 Aseptic necrosis of bone, site unspecified
733.42 Aseptic necrosis of head and neck of femur
733.43 Aseptic necrosis of medial femoral condyle
733.45 Aseptic necrosis of bone, jaw
733.44 Aseptic necrosis of talus
733.49 Aseptic necrosis of bone, other
733.41 Aseptic necrosis of head of humerus

SNOMED

Aseptic necrosis of bone (disorder)
Osteonecrosis due to trauma (disorder)
Idiopathic aseptic necrosis of bone (disorder)
Aseptic necrosis of head AND/OR neck of femur
aseptic necrosis of bone of jaw (disorder)
Aseptic necrosis of talus
Aseptic necrosis of head of humerus (disorder)
Aseptic necrosis of medial femoral condyle

CLINICAL PEARLS

Trauma, alcohol abuse, and prolonged glucocorticoid use are the most common risk factors for developing osteonecrosis.
Suspect oseteonecrosis in high-risk patients presenting with dull bony pain.
Order joint-specific plain films initially and proceed to MRI if needed for definitive diagnosis.
Patients on chemotherapy are at higher risk for mandibular osteonecrosis.

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