February 2025

Avascular necrosis (AVN), also known as osteonecrosis, is a condition that occurs when there is a loss of blood supply to the bone, leading to the death of bone cells. It most commonly affects the hip joint, causing debilitating pain, impaired mobility, and potentially leading to joint collapse. In this article, we will explore all aspects of AVN of the hip, including its pathophysiology, risk factors, clinical presentation, diagnostic methods, treatment options, and long-term management strategies. 1. Introduction Avascular necrosis (AVN) of the hip is a serious condition that affects the femoral head, the ball-shaped structure at the top of the femur that fits into the acetabulum of the pelvis to form the hip joint. The loss of blood supply to the femoral head leads to bone cell death, weakening the bone and eventually causing it to collapse. As the bone deteriorates, the joint loses its structural integrity, leading to pain, stiffness, and functional impairment. The hip joint is crucial for weight-bearing activities and is subject to significant mechanical stress during movement. AVN of the hip can severely affect the quality of life, causing chronic pain and disability. The disease is often progressive and may result in osteoarthritis, requiring surgical intervention, most commonly total hip replacement (THR). 2. Pathophysiology of Avascular Necrosis of the Hip The hip joint is highly vascularized, with blood supply provided by branches from the femoral artery, particularly the medial and lateral circumflex arteries. In AVN, there is a disruption in this blood supply, leading to ischemia (lack of blood flow) in the femoral head. Without adequate blood flow, bone cells (osteocytes, osteoblasts, and osteoclasts) are deprived of essential nutrients and oxygen, causing them to die. Over time, the bone structure weakens and collapses, leading to deformities in the hip joint. The initial stage of AVN involves bone cell death and necrosis of trabecular bone, which is the spongy bone inside the femoral head. As the disease progresses, subchondral bone (the bone just beneath the cartilage) is affected, leading to cartilage destruction and joint degeneration. In the final stages, the femoral head can collapse completely, causing severe pain, joint deformity, and loss of function. The collapse of the femoral head results in joint incongruity and a decrease in the congruency between the femoral head and the acetabulum, which impairs the normal function of the hip joint. This damage can lead to secondary osteoarthritis and the development of debilitating hip pain. 3. Risk Factors for Avascular Necrosis of the Hip Several risk factors contribute to the development of AVN of the hip, some of which are modifiable, while others are non-modifiable. Understanding these risk factors is essential for both prevention and early diagnosis. a. Trauma One of the most common causes of AVN is traumatic injury to the hip, such as fractures of the femoral neck or dislocations of the hip joint. Trauma can damage the blood vessels supplying the femoral head, leading to ischemia and necrosis. b. Corticosteroid Use Long-term use of corticosteroids, particularly at high doses, is a well-established risk factor for AVN of the hip. Corticosteroids are thought to cause AVN by several mechanisms, including direct toxicity to osteoblasts, increased intraosseous pressure, and fat embolism that obstructs blood vessels. The risk increases with higher cumulative doses and prolonged use. c. Alcohol Consumption Excessive alcohol intake has been linked to AVN, as it can cause fatty infiltration of the bone marrow and increase intraosseous pressure, leading to compromised blood flow. Chronic alcohol abuse is one of the most significant non-traumatic risk factors for AVN. d. Systemic Diseases Certain systemic diseases are associated with an increased risk of AVN. These include: e. Inherited Conditions Genetic predispositions can also play a role in the development of AVN. For example, individuals with familial hyperlipidemia or those with certain genetic mutations may have an increased risk of developing AVN. f. Other Factors 4. Clinical Presentation The symptoms of AVN of the hip depend on the stage of the disease. In the early stages, patients may experience mild symptoms, while later stages are characterized by severe pain and loss of function. a. Early Stage In the early stages, AVN may be asymptomatic or present with vague symptoms such as mild hip pain or discomfort, which worsens with weight-bearing activities. The pain may be intermittent and is often described as aching or throbbing in nature. It may be localized to the groin, thigh, or buttock. b. Progressive Stage As the disease progresses and bone necrosis increases, patients may experience more persistent pain. The pain becomes more intense, particularly with activity, and may be accompanied by stiffness and limited range of motion. Patients may also experience difficulty walking and may begin to limp. c. Advanced Stage In the advanced stages of AVN, the femoral head may collapse, leading to severe pain and disability. The pain is often constant and can radiate down the thigh or into the knee. Joint movement becomes severely restricted, and patients may have difficulty performing daily activities such as standing, walking, or climbing stairs. 5. Diagnostic Methods Diagnosing AVN of the hip requires a thorough clinical examination, medical history review, and imaging studies. a. Clinical Examination The clinician will perform a physical examination to assess the patient’s range of motion, gait, and tenderness in the hip joint. They may also test for the impingement sign and perform provocative maneuvers to assess for hip joint instability. b. Imaging Studies 6. Treatment Options The treatment of AVN of the hip depends on the stage of the disease, the patient’s age, activity level, and overall health. The goal of treatment is to relieve pain, prevent further bone collapse, and preserve the joint as much as possible. a. Conservative Management b. Surgical Treatment In advanced cases of AVN, surgical intervention is often required. Several surgical options are available, depending on the stage of the disease and the patient’s specific circumstances. 7. Prognosis and Long-Term Management The prognosis of AVN depends on the stage at which the condition is diagnosed and the

Introduction : Gait: It is a medical term used for the way a person walks . In some people gait is abnormal may be due to some injury or due to under lying medical conditions. Abnormal gait is also called as AMBULATORY DYSFUNCTION. Any thing that affects brain, spinal cord, legs or feet leads to change in gait . Normal Gait : Normal gait is nothing but normal walking without any abnormalities . One complete gait cycle is completed when it begin with heel strike of a foot continues till heel strike of identical foot. Human gait : It can be defined as a series of alternating movements of the lower extremities in a rhythmic motion that results in forward progression of body with minimal energy expenditure . It means it takes 2 steps to complete a full gait cycle. Gait cycle has 2 phases : STANCE PHASE : The time duration of foot on ground , it occupies 60% of gait cycle . It starts when foot touches the ground and ends when the foot leaves the ground. SWING PHASE : The time duration of foot in air, it occupies 40% of gait cycle .I t start when foot leaves the ground and end when same foot touches the ground again. Important support phases : SINGLE SUPPORT PHASE [Swing Phase] : In this phase only one limb is in contact with ground . INITIAL DOUBLE SUPPORT PHASE : It is the sub phase between the heel contact to contralateral foot off. It shows 14 to 20% of stance phase . TERMINAL DOUBLE SUPPORT PHASE : Itis sub phase from contralateral foot on to toe off, It shows 14 to 20% of stance phase . TOTAL DOUBLE SUPPORT PHASE : It shows 28 to 40% of stance phase . As it is the sum of initial double support phase and terminal double support phase . NOTE : More problems will appear during stance phase of gait when foot is loaded which in turn shows impact on the swing phase . The Phases of Human Walking: A Step-by-Step Breakdown GAIT ABNORMALITIES : Most common type , resulted due to pain in lower extremities like pain in muscle , joints or in bones . Limping is seen this type of gait , means avoiding steeping or pressure on affected leg . keeping ankle fixed in the one position while lifting and lowering the foot. This may include following causes like : 2.PROPULSIVE GAIT : It is also called as PARKINSONS GAIT or FESTINATING GAIT . As it is seen in Parkinson’s disease , one can observe stooping means head and neck are bend forwards and downward and rigid posture is seen . Steps are short and fast to maintain center of gravity, hence called as festinating gait .Also seen in carbon monoxide poison . 3 .SCISSORS GAIT : In this type the knees and thighs hits or cross in a scissor like pattern during walk and slow and small steps are seen and this type of gait is diagnosed in spastic cerebral palsy. severe adduction of legs and hitting of the knees and thighs . 4. SPASTIC GAIT : It is also called as hemiplegic gait ,In this type of gait one leg is stiffened while walking . If lifted to walk it is either dragged or swings around in semicircular motion [ circumduction ] . This condition is seen in cerebral palsy , multiple sclerosis , Hemiplegia. 5. STEPPAGE GAIT : It is also called as neuropathic gait ,in this high step is seen means person elevates hip to lift leg higher than normal . Foot appears floppy when it drops and toes point down and scrape ground this type of gait is diagnosed in muscle atrophy or peroneal nerve injury [ like in spinal stenosis or herniated disc ] 6.WADDILING GAIT : In this exaggerate movement of upper body is observed like a duck , hence it is also called as duck walk . This type of gait is diagnosed in hip dislocation , progressive muscular dystrophy. It is also called as myopathic gait . Some times pregnancy women also adopt waddling gait as protective measure to prevent falling. 7. CROUNCHING GAIT : In this gait flexing of ankles, knees and hip is seen while walking . Characteristics like bending down while walking , toe dragging are seen this gait abnormality is diagnosed in cerebral palsy. 8. ATAXIC GAIT : In this irregular steps , person can’t walk in straight line when walk heel to toe [ unsteady walk ]. This abnormality is diagnosed in cerebellar degeneration .Vitamin deficiencies like low levels of vitamin E, B-1, or B-12 and in Sensory disturbances like vision or proprioception disorders 9. SHUFFLING GAIT : In this type of gait feet is not completely lifted off the ground and feet get dragged while walking . This type of gait is seen in medical conditions like Parkinson’s disease , Muscle strain and in nerve damage conditions etc. Symptoms like shot steps ,stooped posture , flexed knees are observed . 10. LURCHING GAIT : This type of gait abnormality is caused due to paralysis or weakness of gluteus muscles or other conditions that affect the hip or legs . In this gait type one may observe slow and long stride . Conclusion : In conclusion, understanding the various types of gait is essential for recognizing and addressing different physical conditions and movement patterns. Gait analysis plays a crucial role in diagnosing and treating mobility issues, whether they stem from neurological disorders, orthopedic injuries, or natural aging. By studying common gait types such as the antalgic, ataxic, and spastic gaits, medical professionals can develop targeted interventions and rehabilitation plans. Additionally, the influence of environmental factors and individual differences in biomechanics further emphasizes the need for personalized care. Overall, analyzing and categorizing gait types not only aids in better medical outcomes but also promotes the importance of early detection and proactive management in maintaining overall mobility and