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Diagnosis And Treatment
Diagnosis of AVN needs a comprehensive approach involving clinical inputs and radiological findings.
Clinical findings:
A doctor examines the patient thoroughly and checks for tenderness in joints. He might move joints through a variety of positions to check patient’s range of motion. In addition to the physical examination, understanding patient’s age along with detailed history is equally important. Occurrence of serious diseases in the past or previous medications may provide some diagnostic clues.
My Hip Score
In 1969, Dr William H.Harris developed a hip scoring system which is currently being used by orthopedic surgeons all over the world.
Higher the score, the better. Low score indicates urgent need of doctor consultation.
Measure your score now.
1.
Need support while walking.
No need
Needs support for long walks
Needs support most of the times
One crutch
Two canes
Two crutches or inability to walk
Imaging/ Radiology
Obtaining image of bone is crucial for diagnosis of AVN. Usually a patient is asked to undergo a simple X-ray image of the joint.
Magnetic Resonance Imaging (MRI) is recommended for early stage from the disease onset. It is the most sensitive and specific method of Diagnosing AVN. It has the ability to detect the disease as early as 5 days after initiation of necrosis!
Radiological findings are essential to determine the Stage of disease and quantity of bone death.
Stages of Osteonecrosis
Stage of the disease gives idea about the progress of the disease. It simply means how much of the bone area is dead.. Various systems are being used for disease staging however, a system formulated by the Association Research Circulation Osseous (ARCO) is widely used in clinical practice.2
| How your bone looks |  |
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| Symptoms | No symptoms | Mild symptoms | Severe pain and restricted movements | Severe pain and inability to move the joint |
| What does imaging test say? | Normal X-ray but abnormal MRI | X-ray shows presence of dead tissue even if the head of femur (thigh bone) appears normal in shape | Flattening of head of femur is observed and also fractures in the bone. If flattening of femur head is ≤2mm, it is stage IIIA. But if it is > 2mm it is stage IIIB. Additionally loosening of the cartilage is seen. | Joint destruction is seen with narrowing of joint space. Increased deterioration of bone tissue is seen on MRI. Cartilage is completely destroyed. |
| Stage | I II | III | IV | |
| Treatment Options |
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How treatment works?
Disease Management (Temporary Measures)
Bisphosphonates:
They inhibit the action of osteoclasts, which play a function of bone degradation. In this way bisphosphonates inhibit the process of bone degradation. As the degradation is hampered probability of bone collapse is reduced. They also stimulate proliferation of pro-osteoblast cells which synthesize bone cells. They help in reduction of swelling at the site of AVN.5,6
Vasoactive substances:
They bring about widening of terminal blood thereby improvement in blood flow.5
Bone grafting:
Generally done through the core decompression tract, the process involves filling the drilled area with either living bone tissue (obtained from other area) or non-vascularized tissue. The former helps in ingrowth of vascular cellular tissue in the region of dead bone whereas the later provides the structural stability to the hip.5,7
Bone Cell Therapy:
It is a newer treatment modality wherein bone cells called Osteoblasts are introduced in the dead bone to prevent bone collapse after core decompression. The reports published in the peer renewed international journal – cited encouraging with more than 70% of patients not requiring hip replacement surgery at even 8 years.
Cholesterol lowering agents:
They reduce the number and size of circulating fat cells in the blood and hence reduce the risk of developing AVN.
Blood thinners:
They inhibit platelet aggregation and thus avoid formation of blood clots. It leads to increased blood flow to the bone.5
Core decompression (CD):
It’s a common procedure to treat AVN. It’s a surgical procedure wherein a drill is made in the area of dead bone near the joint. This reduces pressure, increases blood flow and slows the process of bone destruction5. However this technique does not form new bone.
Total hip replacement:
It is the end stage treatment required in case of joint collapse. In the last stage of AVN when bone is completely dead, the individual is in deep pain and unable to move joint. In such cases total hip replacement is the only option. In this treatment, the damaged bone and cartilage is removed and replaced with artificial metal joint.5 The shelf life of the metal prosthesis and recent infection news are recent causes of concern Treatment is decided considering the age of the patient and stage of the disease. It is generally recommended after other options fail and age is over 60 years.
It should be remembered that AVN is a
progressive disease. Early diagnosis is better
for better treatment outcome.
References:
- Nildoster A, Bremander A. Measures of hip function and symptoms. Arthritis Care & Research. 2011;63(S11):S200-7.
- Zhao D, Zhang F, Wang B, et al. Guidelines for clinical diagnosis and treatment of osteonecrosis of the femoral head in adults (2019 version). Journal of orthopaedic translation. 2020 Mar 1;21:100-10.
- Osteonecrosis of the Hip. Available from: https://orthoinfo.aaos.org/en/diseases--conditions/osteonecrosis-of-the-hip#:~:text=The%20four%20stages%20of%20osteonecrosis,IV%20osteonecrosis%20of%20the%20hip.. Accessed on: 9th April 2021
- Choudhary J et al., Magnetic Resonance Imaging in Evaluation of Avascular Necrosis of Femoral Head. International Journal of Scientific Study. 2019:7 (7):50-55.
- Moya-Angeler J, Gianakos AL, Villa JC, et al., Current concepts on osteonecrosis of the femoral head. World journal of orthopedics. 2015 Sep 18;6(8):590.
- Agarwala S, Jain D, Joshi VR, et al. Efficacy of alendronate, a bisphosphonate, in the treatment of AVN of the hip. A prospective open-label study. Rheumatology. 2005 Mar 1;44(3):352-9.
- Allsopp BJ, Hunter-Smith DJ, Rozen WM. Vascularized versus nonvascularized bone grafts: what is the evidence?. Clinical Orthopaedics and Related Research®. 2016 May 1;474(5):1319-27.
- Andriolo L, Merli G, Tobar C, et al. Regenerative therapies increase survivorship of avascular necrosis of the femoral head: a systematic review and meta-analysis. International orthopaedics. 2018 Jul;42(7):1689-704.