Hip Pathology and Disorders

Hip pathology covers disorders of the deep ball-and-socket joint between the femoral head and acetabulum — most prominently osteoarthritis, but also femoroacetabular impingement, developmental and structural abnormalities, and avascular necrosis. The hip's stability and weight-bearing role make degenerative disease a leading cause of pain and disability, and total hip replacement is among the most successful interventions in surgery.

Definition

Hip pathology and disorders comprise the degenerative, structural, developmental, and ischaemic conditions affecting the femoroacetabular joint, surrounding capsule, and adjacent bone.

Scope

This topic surveys the major degenerative, structural, and developmental conditions of the hip joint, the impingement model linking joint shape to osteoarthritis, and the role of joint replacement. It is a reference-educational overview, not clinical guidance.

Core questions

• What are the principal hip disorders — osteoarthritis, impingement, dysplasia, and avascular necrosis?
• How does joint shape relate to the development of hip osteoarthritis?
• Why is the hip especially susceptible to degenerative disease?
• What is the role of total hip replacement in end-stage hip disease?

Key concepts

• Hip osteoarthritis
• Femoroacetabular impingement (cam and pincer)
• Developmental dysplasia of the hip
• Avascular (osteonecrosis) of the femoral head
• Total hip replacement
• Ball-and-socket joint mechanics

Mechanisms

The hip is a deep, congruent ball-and-socket joint that combines stability with the load-bearing demands of standing and gait. Osteoarthritis of the hip involves progressive cartilage loss, subchondral bone change, and synovial inflammation, and is a major contributor to musculoskeletal disability (Hunter 2019). The femoroacetabular impingement model proposes that subtle abnormalities in the shape of the femoral head-neck junction (cam type) or the acetabular rim (pincer type) cause repetitive abnormal contact that damages the labrum and cartilage and may predispose to osteoarthritis (Ganz 2003). When joint destruction is advanced, total hip replacement reliably relieves pain and restores function and is regarded as one of the most effective operations in modern surgery (Learmonth 2007).

Clinical relevance

Hip disorders, led by osteoarthritis, are a frequent reason for orthopedic referral and a major driver of joint replacement. Understanding the impingement model and the evidence on joint replacement is central to appraising the literature on hip disease. This entry describes how hip conditions are categorised and studied and is not a basis for individual treatment decisions.

Epidemiology

Hip osteoarthritis is common and rises with age, contributing substantially to the global burden of musculoskeletal disability (Hunter 2019). Femoroacetabular impingement morphology is found in a notable share of populations, though its relationship to symptomatic disease varies, and developmental dysplasia is a recognised contributor to early osteoarthritis.

History

The development of low-friction total hip arthroplasty in the mid-twentieth century transformed the management of end-stage hip disease and is celebrated as a landmark of surgical innovation (Learmonth 2007). Early in the twenty-first century, the femoroacetabular impingement concept reframed how subtle joint-shape abnormalities are understood as potential precursors of hip osteoarthritis (Ganz 2003).

Debates

How strongly does femoroacetabular impingement cause osteoarthritis?

The impingement model links cam and pincer morphology to labral and cartilage damage and possible later osteoarthritis, but the morphology is common in asymptomatic people, so the strength and clinical significance of the association remain debated.

Seminal works

• hunter-2019
• ganz-2003
• learmonth-2007

Frequently asked questions

What is femoroacetabular impingement?

It is a proposed mechanism in which subtle abnormalities in the shape of the femoral head-neck junction or the acetabular rim cause repetitive abnormal contact that can damage the labrum and cartilage and may contribute to hip osteoarthritis.

Why is total hip replacement considered so successful?

For advanced hip disease, total hip replacement reliably relieves pain and restores function, which is why it is often described as one of the most effective operations in modern surgery.