Femoral Head Avascular Necrosis Workup
- Author: John D Kelly IV, MD; Chief Editor: Sherwin SW Ho, MD more...
Laboratory Studies
- Routine laboratory studies are of little value in the evaluation of femoral head AVN other than to rule out other conditions that may cause hip pain (eg, rheumatoid arthritis). (See also the eMedicine articles Rheumatoid Arthritis [in the Physical Medicine and Rehabilitation section], Rheumatoid Arthritis [in the Rheumatology section], and Juvenile Rheumatoid Arthritis [in the Pediatrics section], as well as the Rheumatoid Arthritis Resource Center on Medscape.)
- Hematologic studies may reveal sickle cell disease, if clinically suspected. (See also the eMedicine articles Sickle Cell Anemia [in the Pediatrics section] and Pediatrics, Sickle Cell Disease [in the Emergency Medicine section].)
- Subtle coagulation disturbances (eg, hypofibrinolysis, thrombophilia) are frequent findings, but the significant cost and limited availability of the sophisticated coagulation tests that are necessary for these diagnoses argue against routine screening.
Imaging Studies
- Plain radiographs
- Obtain anteroposterior and frog-leg lateral views of both hips. The high incidence of bilaterality (>60%) and occult disease in cases of femoral head AVN warrant imaging of the unaffected leg.
- Early radiographic findings include femoral head lucency and subchondral sclerosis.
- With disease progression, subchondral collapse (ie, crescent sign) and femoral head flattening become evident radiographically. Joint space narrowing is the end result of untreated femoral head AVN.
- Radiographic staging of AVN was first proposed by Ficat and Arlet in the 1960s and later amended in the 1970s.[5] This 4-stage system delineates the natural history of AVN from normal radiographs (stage I) to cystic changes and sclerosis (stage II), to subchondral collapse or femoral head flattening (stage III), and finally to joint space narrowing (stage IV). However, this system does not differentiate among certain phases in disease progression (eg, subchondral vs femoral head collapse), nor does it quantify the size and extent of the lesion.
- Steinberg proposed the following staging system, known as the Steinberg Classification System, which is concise and delineates the progression and extent of AVN involvement more accurately.[6, 7] This staging system has gained increasing acceptance in the orthopedic community.
- Stage I – Normal radiographs; abnormal MRI or bone scan
- Stage II – Abnormal lucency or sclerotic site in femoral head
- Stage III – Subchondral collapse (ie, crescent sign) without flattening of femoral head
- Stage IV – Flattening of the femoral head; normal joint space
- Stage V – Joint space narrowing, acetabular changes, or both
- Stage VI – Advanced degenerative changes
- Stages I-IV are further subdivided according to the percentage of femoral head involvement: A (< 15%), B (15-30%), or C (>30%).
- MRI
- MRI is the study of choice in patients who demonstrate signs and symptoms that are suggestive of AVN but whose radiographs are normal.
- MRI is the most sensitive and specific means of diagnosing AVN. MRI may detect disease as early as 5 days subsequent to an ischemic insult.
- Characteristic MRI findings for AVN of the hip include a low signal intensity band (seen on T1 and T2 images) that demarcates a necrotic anterosuperior femoral head segment. The extent and location of femoral head necrosis on MRIs have been studied as predictors of femoral head collapse. Smaller lesions (less than one fourth the diameter of the femoral head) and more medial lesions (away from primary weight-bearing areas) predict a better outcome.[7]
- Bone scanning
- Abnormalities may show up on a bone scan before they do on plain radiographs. Bone scan findings should be supplemented with MRI findings.
- The presence of a photopenic area that is surrounded by increased tracer uptake is the typical scintigraphic picture for radionuclide imaging.
- Bone scans are considerably less sensitive and less specific than MRI, but the images may be useful if the use of MRI is contraindicated.
- Computed tomography (CT) scanning
- CT scans confer significant radiation exposure to the patient and are less sensitive than MRI in diagnosing AVN.
- CT scanning may help delineate early subchondral collapse because the resolution of bony architecture with this modality is unsurpassed.
- Angiography is an invasive mean of diagnostic confirmation of AVN; it is most useful as an investigational modality.
Procedures
- Biopsy, angiography, and measuring bone marrow pressure are invasive measures of confirming the diagnosis of AVN, but these procedures are most useful as investigational modalities.
Lavernia CJ, Sierra RJ, Grieco FR. Osteonecrosis of the femoral head. J Am Acad Orthop Surg. Jul-Aug 1999;7(4):250-61. [Medline].
Vail TP, Covington DB. The incidence of osteonecrosis. In: Urbaniak JR, Jones JR, eds. Osteonecrosis: Etiology, Diagnosis, Treatment. Rosemont, Ill: American Academy of Orthopedic Surgeons; 1997:43-9.
Mont MA, Hungerford DS. Non-traumatic avascular necrosis of the femoral head. J Bone Joint Surg Am. Mar 1995;77(3):459-74. [Medline].
Pritchett JW. Statin therapy decreases the risk of osteonecrosis in patients receiving steroids. Clin Orthop Relat Res. May 2001;386:173-8. [Medline].
Arlet J, Ficat P. [Non-traumatic avascular femur head necrosis. New methods of examination and new concepts] [Polish]. Chir Narzadow Ruchu Ortop Pol. 1977;42(3):269-76. [Medline].
Steinberg ME. Avascular necrosis: diagnosis, staging, and management. J Musculoskel Med. 1997;14(11):13-25.
Steinberg ME. Diagnostic imaging and the role of stage and lesion size in determining outcome in osteonecrosis of the femoral head. Techniques in Orthopaedics. Mar 2001;16(1):6-15. [Full Text].
McGrory BJ, York SC, Iorio R, et al. Current practices of AAHKS members in the treatment of adult osteonecrosis of the femoral head. J Bone Joint Surg Am. Jun 2007;89(6):1194-204. [Medline].
Ciombor DM, Aaron RK. Biologically augmented core decompression for the treatment of osteonecrosis of the femoral head. Techniques in Orthopaedics. Mar 2001;16(1):32-8. [Full Text].
Katz MA, Urbaniak JR. Free vascularized fibular grafting of the femoral head for the treatment of osteonecrosis. Techniques in Orthopaedics. Mar 2001;16(1):44-60. [Full Text].
McCarthy J, Puri L, Barsoum W, et al. Articular cartilage changes in avascular necrosis: an arthroscopic evaluation. Clin Orthop Relat Res. Jan 2003;406:64-70. [Medline].
Ivankovich DA, Rosenberg AG, Malamis A. Reconstructive options for osteonecrosis of the femoral head. Techniques in Orthopaedics. Mar 2001;16(1):66-79. [Full Text].
Squire M, Fehring TK, Odum S, Griffin WL, Bohannon Mason J. Failure of femoral surface replacement for femoral head avascular necrosis. J Arthroplasty. Oct 2005;20(7 suppl 3):108-14. [Medline].
Glueck CJ, Freiberg RA, Sieve L, Wang P. Enoxaparin prevents progression of stages I and II osteonecrosis of the hip. Clin Orthop Relat Res. Jun 2005;435:164-70. [Medline].
[Best Evidence] 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. Oct 2005;87(10):2155-9. [Medline].
DeLee JC. Fractures and dislocations of the hip. In: Rockwood CA, Green DP, Bucholz RW, eds. Rockwood and Green's Fractures in Adults. 4th ed. Philadelphia, Pa: Lippincott-Raven; 1996:1661-9.
Etienne G, Mont MA, Khanuja HS, Hungerford DS. Nonvascularized bone grafts for osteonecrosis of the femoral head: current concepts and techniques. Techniques in Orthopaedics. Mar 2001;16(1):39-43. [Full Text].
Kim SY, Kim YG, Kim PT, et al. Vascularized compared with nonvascularized fibular grafts for large osteonecrotic lesions of the femoral head. J Bone Joint Surg Am. Sep 2005;87(9):2012-8. [Medline].
Urbaniak JR, Barnes CJ. Meeting the challenge of osteonecrosis in adults. J Musculoskel Med. 2001;18:395-403.
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