Reconstruction Cases Avascular necrosis

A 51-year-old male presents with a chief complaint of left hip pain that has been progressively worsening for the past 6 months. He has groin pain and describes radiation to his knee. He has been taking a nonsteroidal anti-inflammatory medication with some relief but continues to limp and experience severe pain after walking to clinic.

Patient states a history of anxiety and COPD with inhaled corticosteroids treatment more than 10 years ago. Three years ago the patient was diagnosed with myelodysplasia and underwent a bone marrow transplant. He smokes half a pack of cigarettes per day and uses alcohol occasionally. He previously used heroin.

An x-ray is obtained (Fig. 7–3). What further studies would be recommended next in his management?

1. Ultrasound

2. Frog-leg lateral hip radiograph

3. CT pelvis and hip

4. Bone scan

5. Arthrogram

    

    

    

   Figure 7–3

    

   Discussion

   The correct answer is (B). Based upon clinical history, the differential diagnosis in this patient may include stress fracture, femoroacetabular impingement, avascular necrosis, and tumor. While this patient’s AP hip x-ray reveals osteonecrosis/avascular necrosis (AVN) of the left hip, this diagnosis is often missed on initial AP and shoot-through lateral radiographs. A frog-leg lateral visualizes the anteromedial part of the joint where collapse is initially observed. The Ficat–Arlet classification for osteonecrosis is based upon the following radiographic criteria:

   1. Normal radiographs

   2. Diffuse sclerosis and cysts

   3. Subchondral fracture (crescent sign with or without collapse)

   4. Femoral head collapse, acetabular involvement, and arthritis

      Ficat/Arlet stage I and II involve the precollapse period and are associated with the best prognostic value. Early disease can be detected on MRI imaging. Bilateral hip disease occurs in 50% of cases of osteonecrosis in which the cause is systemic (i.e., in most etiologies with the exception of unilateral hip trauma), therefore an MRI of the pelvis is indicated to evaluate the asymptomatic contralateral hip (Fig. 7–4). The Steinberg classification of femoral head osteonecrosis has been adapted to include MRI findings.

       

       

       

      Figure 7–4

       

      The patient is quite anxious about his diagnosis and insists that since he has had no trauma and no family history of osteonecrosis the diagnosis must be incorrect. Which of these conditions in the patient’s history has been linked directly to AVN?

      1. Corticosteroid inhalers

      2. Hematologic disorders and myelodysplasia

      3. Heroin abuse

      4. Advanced age

Discussion

The correct answer is (B). Avascular necrosis is not well understood. The thought that vascular compromise may be associated with the injury has provided the premise for some early treatments but outcomes are inconsistent.

Trauma, sickle cell disease, hematologic disorders, Caisson disease, and irradiation are associated with AVN. The condition though has also been linked to systemic corticosteroid medications, alcohol abuse, smoking, and viral diseases including CMV, HIV/antiretroviral treatment, rubella, and varicella.

Radiation, hematologic disease, HIV, asthma, alcoholism, and sickle cell disease are associated with AVN. In sickle cell disease, asymptomatic patients with MRI-detectable femoral head osteonecrosis will develop femoral head collapse in more than:

1. 10% of cases

2. 30% of cases

3. 60% of cases

4. 70% of cases

5. 100% of cases

 

Discussion

The correct answer is (D). According to several studies, most patients with sickle cell and early symptoms of AVN diagnosed on imaging will progress to collapse. Hernigou et al. documented the natural history of osteonecrosis of the femoral head in 121 initially asymptomatic patients with sickle cell disease and showed 91% developed hip pain and 77% demonstrated collapse over a 10-year period.

The patient requests any possible treatment to improve his chances of keeping his native hip healthy and remain active through his older years. He inquires if he should either try crutches or the option for some kind of surgery to help the lesions heal. You suggest that the treatment algorithm that is currently recommended for stage I disease involves:

1. Crutches and nonweight bearing

2. Low-intensity pulsed ultrasound (LIPUS)

3. Statins and vasodilators to counteract the avascular process

4. Core decompression and percutaneous drilling

5. Total hip replacement

Discussion

The correct answer is (D). Nonweight bearing has not been a particularly successful treatment modality. LIPUS has been tried with similarly low success. Pharmacological treatment has also been attempted with statins, vasodilators, and anticoagulants showing no clear improvement in AVN.

Bisphosphonate treatment can be of benefit in early osteonecrosis. The inhibition of osteoclasts and the resorption process was thought to slow weakening of the femoral head and collapse. Some studies have shown no change in progression of disease with a need for arthroplasty while other studies have shown a benefit.

The current algorithms for AVN involve core decompression for stage I or II (precollapse) disease. Over 80% of stage I diseases and 60% of stage II diseases have been shown to be successfully managed with decompression or drilling. Once collapse has occurred, the overall outcomes worsen significantly. Bone grafting is an option but patients often progress to require a total hip replacement.

The patient continues to have pain following nonoperative treatment. He has read about hip resurfacing and despite your caution of metal-on-metal bearings, he would like to proceed with hip resurfacing. You further caution him that he is at higher risk of failure due to:

1. His young age

2. Male gender

3. Osteonecrosis of the femoral head

4. Arthritis

5. Comorbidities

 

Discussion

The correct answer is (C). Even though currently out of favor due to increasing concerns regarding the systemic and local sequelae of metal ions, the results of hip resurfacing have been most successful in patients under 55 years of age, male, with a diagnosis of osteoarthritis. Resurfacings in patients with AVN have higher risk of failure due to presence of osteonecrosis into the femoral neck. Total hip arthroplasty yields more reproducible results in this setting.

Nevertheless, total hip replacement in younger patients and patients with AVN has been shown to have a higher failure rate compared to the older population.

 

Helpful Tip:

Groin pain in a younger patient with risk factors for AVN should be evaluated closely. Frog lateral will show collapse, but in the absence of those findings an MRI should be obtained to rule out a fracture or early stages of AVN. Based on the degree of disease, bisphosphonates, core decompression and drilling, bone grafting, limited replacements including hemiarthroplasty, and total hip replacements can be performed. Hip preservation techniques are recommended for precollapse disease, and arthroplasty is recommended for postcollapse. Younger patients with more advanced disease have overall worse outcomes in the long term.

 

Objectives: Did you learn...?

 

Recognize AVN, x-ray, and MRI findings?

 

 

Know the comorbidities associated with AVN and their direct or indirect risk? Understand the treatment algorithm?