Hip osteoarthritis (OA) is a chronic degenerative joint disorder characterized by progressive deterioration of articular cartilage, changes in subchondral bone, osteophyte formation, and narrowing of the joint space. These structural changes lead to pain, stiffness, reduced range of motion, muscle weakness, gait abnormalities, and functional limitations, ultimately affecting mobility, independence, and quality of life. Hip osteoarthritis is a common musculoskeletal condition, particularly in middle-aged and older adults, with global prevalence estimates indicating that approximately 5-10% of adults over the age of 45 are affected. Mechanical factors such as altered joint biomechanics, abnormal load distribution across the hip joint, femoroacetabular impingement, repetitive joint loading, previous trauma, and weakness of surrounding musculature play a significant role in the development and progression of the disease.
Radiographic assessment is commonly used to classify the severity of hip osteoarthritis, with the Kellgren-Lawrence (KL) grading system being the most widely accepted. The KL classification ranges from Grade 0 to Grade IV. Grade 0 indicates no radiographic evidence of osteoarthritis. Grade I shows doubtful joint space narrowing with possible osteophyte formation. Grade II is characterized by definite osteophyte formation with possible joint space narrowing. Grade III includes multiple moderate osteophytes, definite joint space narrowing, sclerosis, and possible bony deformity. Grade IV represents severe osteoarthritis with large osteophytes, marked joint space narrowing, severe sclerosis, and definite bony deformity. Grade II hip osteoarthritis represents an early stage of the disease in which conservative management is strongly recommended to reduce symptoms, improve function, and slow disease progression.
Exercise therapy is a core component of conservative management for hip osteoarthritis and plays a vital role in improving muscle strength, joint stability, range of motion, and overall functional performance. Strengthening of the hip abductor muscles is particularly important, as these muscles contribute to pelvic stability and optimal load transfer during functional activities such as walking and stair climbing. Clamshell exercises are commonly prescribed to activate and strengthen the gluteus medius and minimus muscles. Modified clamshell exercises involve changes in positioning or execution to enhance muscle recruitment, improve neuromuscular control, and minimize compensatory movements, potentially resulting in improved clinical outcomes.
