Hip Dysplasia: Symptoms, Types, Causes and Treatment

Hip dysplasia is a condition that affects the structure and function of the hip joint, leading to pain, instability, and, if left untreated, early osteoarthritis. Though commonly associated with infants and children, hip dysplasia can persist or present anew in adolescence and adulthood, impacting mobility and quality of life. In this comprehensive article, we'll explore the symptoms, types, causes, and treatment options for hip dysplasia, drawing on the latest evidence and expert recommendations.

Symptoms of Hip Dysplasia

Hip dysplasia often goes unnoticed in its early stages, especially in newborns and young children, but as the condition progresses, symptoms can become pronounced and disruptive. Early recognition of these signs is crucial for timely intervention and improved outcomes.

Symptom	Description	Common Age Group	Source
Hip pain	Insidious, often in groin or lateral hip area	Adolescents, Adults	1 4
Limping	Abnormal gait due to hip instability	Children, Adults	5 6
Limited motion	Reduced hip abduction, stiffness	Infants, Children	2
Clicking/popping	Sensation or sound during movement	All ages	1 5
Early arthritis	Premature joint degeneration, pain	Young Adults	4 5

Table 1: Key Symptoms

Overview of Symptom Presentation

Symptoms of hip dysplasia can be subtle or pronounced, depending on age, activity level, and the severity of dysplasia.

Hip Pain

• Adolescents and young adults often report a gradual onset of hip pain, typically felt deep in the groin or on the outer side of the hip, sometimes described as a C-shaped distribution around the inguinal crease. This pain is usually aggravated by activity and may persist for months or even years before diagnosis 1 4.
• In infants and toddlers, pain is less common, but irritability or reluctance to move the affected leg can be a clue.

Limping and Gait Changes

• Children and adults may develop a noticeable limp due to hip instability or subtle differences in limb length 5 6.
• The limp is often painless at first but can progress as the condition worsens.

Limited Range of Motion

• In infants, limited hip abduction (the ability to move the thigh outward) is a key clinical sign after the first few months of life. This limitation is often detected during routine pediatric examinations 2.
• Stiffness and loss of mobility can also be present in adults as arthritis develops.

Clicking, Popping, and Instability

• Some people experience clicking, popping, or catching sensations in the hip joint, especially with movement. These can be signs of labral tears or instability caused by the malformed joint 1 5.

Early Osteoarthritis

• Untreated hip dysplasia significantly increases the risk of early-onset hip osteoarthritis, resulting in chronic pain and disability at a young age 4 5.

Types of Hip Dysplasia

Hip dysplasia represents a spectrum of anatomical abnormalities, ranging from mild instability to complete dislocation. Understanding the different types is essential for accurate diagnosis and management.

Type	Defining Features	Typical Age/Stage	Source
Acetabular dysplasia	Shallow, underdeveloped hip socket	All ages	1 2 6
Subluxation	Partial displacement of femoral head	Infants, Children	2
Dislocation	Complete loss of contact between joint surfaces	Infants, Severe DDH	2 3
Residual dysplasia	Persistent dysplasia after treatment	Adolescents, Adults	5
Crowe classification	Grading based on dislocation severity	Adults (surgical planning)	3 10

Table 2: Types of Hip Dysplasia

Acetabular Dysplasia

• Characterized by a shallow and sometimes misshapen hip socket (acetabulum), which does not adequately cover the femoral head. This can lead to instability and increased wear on the joint 1 2 6.
• Acetabular dysplasia can be present at birth or develop during growth.

Subluxation and Dislocation

• Subluxation is a partial loss of contact between the femoral head and the acetabulum. It often arises when the supporting structures are weak or the acetabulum is insufficiently deep 2.
• Dislocation refers to a complete loss of contact, with the femoral head displaced entirely out of the socket. This is most commonly seen in untreated or severe cases of developmental dysplasia of the hip (DDH) 2 3.

Residual and Adolescent-Onset Dysplasia

• After initial treatment in childhood, some individuals continue to have residual acetabular dysplasia, which may not become symptomatic until adolescence or adulthood. Others may develop new-onset dysplasia during adolescent growth spurts 5.
• Both forms can result in similar deformities and increase the risk of early arthritis.

Crowe Classification

• In adults, especially when planning surgical interventions such as total hip arthroplasty, the Crowe classification system is used to grade the severity of hip dislocation, ranging from type I (mild) to type IV (severe, high dislocation) 3 10.
• This classification helps guide treatment strategies and anticipate surgical challenges.

Causes of Hip Dysplasia

The development of hip dysplasia is influenced by a blend of genetic, environmental, and mechanical factors. Early detection of risk factors can help prevent long-term complications.

Cause	Description	At-Risk Group	Source
Genetics	Family history, heritable traits	Newborns, Children	2 7
Mechanical Factors	Breech position, tight swaddling	Infants	2
Developmental	Abnormal growth, residual dysplasia	Children, Adolescents	2 5
Structural Abnormalities	Shallow acetabulum, femoral deformities	All ages	6
Other Risk Factors	Female sex, firstborn, oligohydramnios	Newborns	2

Table 3: Causes of Hip Dysplasia

Genetic and Familial Factors

• Hip dysplasia is known to have a genetic component. Family history is a recognized risk factor and is included in most screening protocols for newborns 2 7.
• Although no single gene has been definitively linked to hip dysplasia, certain genetic markers like GDF5 have been implicated in large studies 7.
• Heritability suggests that siblings and children of affected individuals are at higher risk.

Mechanical and Environmental Influences

• Breech presentation (when the baby is positioned feet-first in the womb) increases the risk of DDH due to abnormal pressures on the developing hip joint 2.
• Habitual tight swaddling with the legs extended and together can also impair proper hip development. Modern swaddling guidelines recommend allowing the hips to flex and abduct freely.

Developmental and Structural Abnormalities

• Normal hip development depends on the concentric (well-aligned) positioning of the femoral head within the acetabulum. Dislocation or subluxation during growth leads to inadequate acetabular formation 2 5.
• Structural abnormalities include a shallow, anteverted acetabulum and changes in the femoral head and neck, such as increased anteversion and neck-shaft angle 6.

Other Risk Factors

• Female infants are more commonly affected than males, possibly due to increased ligamentous laxity.
• Firstborn status and reduced amniotic fluid (oligohydramnios) are also associated with a higher risk for DDH 2.

Treatment of Hip Dysplasia

Effective management of hip dysplasia depends on the patient's age, the severity of the condition, and the presence of secondary arthritis. Treatment aims to restore hip stability, relieve symptoms, and prevent or delay the onset of osteoarthritis.

Treatment	Indication	Age/Severity	Source
Pavlik harness	Initial treatment for instability/dislocation	Infants <6 months	2
Closed/Open reduction	Severe dislocation not resolved by harness	Infants, Children	2
Osteotomy (PAO, femoral)	Residual dysplasia, stable hips	Adolescents, Adults	1 4 11
Hip arthroscopy	Labral tears, borderline dysplasia	Young Adults	1 9 11
Total hip arthroplasty	Advanced arthritis, failed joint preservation	Adults	4 8 10

Table 4: Treatment Options

Non-Surgical and Early Interventions

• Pavlik Harness: The first-line treatment for infants under six months with hip instability or dislocation. This soft brace maintains the hips in a position that promotes proper joint development 2.
• Closed or Open Reduction: If the harness fails or the hip is dislocated, surgical intervention may be needed to reduce (reposition) the hip, sometimes guided by imaging. This may be followed by casting 2.

Surgical Options for Children and Adolescents

• Osteotomies: Surgical procedures that reshape and reorient the hip socket or the femur to improve joint alignment and stability. The Bernese periacetabular osteotomy (PAO) is favored for adolescents and young adults with symptomatic acetabular dysplasia and minimal arthritis 1 4 11.
  • Osteotomies can be performed on the pelvis (acetabular) or femur, depending on the site and nature of the deformity 11.
• Hip Arthroscopy: Minimally invasive surgery used to treat labral tears or remove loose bodies, especially in cases of borderline dysplasia. Results are best in patients without significant structural abnormalities 1 9 11.

Adult and Advanced Case Management

• Total Hip Arthroplasty (THA): Joint replacement is recommended for patients with advanced osteoarthritis or when joint-preserving procedures are no longer viable. THA outcomes are generally favorable, though surgical complexity increases with more severe dysplasia 4 8 10.
  • In severe cases (e.g., Crowe type IV), complex reconstructive techniques, such as femoral shortening osteotomy, may be needed to allow proper placement of the prosthesis and avoid nerve injury 10.
• Combined Approaches: Occasionally, a combination of arthroscopic and osteotomy procedures is used, particularly in young adults with mixed pathology 9.

Complications and Prognosis

• Avascular Necrosis: The most serious complication, particularly in infants and young children, can result from excessive force during reduction or prolonged dislocation 2.
• Residual Dysplasia and Osteoarthritis: Even after treatment, some patients may have persistent anatomical abnormalities leading to early degenerative changes 5.
• Long-term Outcomes: Early diagnosis and intervention generally yield excellent results, with many children achieving normal hip function. In adults, surgical techniques continue to evolve, improving outcomes for even the most complex cases 8 10.

Conclusion

Hip dysplasia is a complex, multifaceted condition that requires vigilant screening, early diagnosis, and individualized management. By understanding its symptoms, types, causes, and treatment options, patients and healthcare providers can work together to prevent long-term disability and improve quality of life.

Key takeaways:

• Symptoms: Can be subtle or pronounced, including pain, limp, limited motion, and early arthritis 1 2 4 5 6.
• Types: Range from mild acetabular dysplasia to severe dislocation; Crowe classification is used for adults 1 2 3 5 6 10.
• Causes: Multifactorial; includes genetic, mechanical, and developmental factors 2 5 6 7.
• Treatment: Age and severity guide management, from harnesses in infants to osteotomies, arthroscopy, and joint replacement in older children and adults 1 2 4 8 9 10 11.

Prompt recognition and proper intervention are essential for optimal outcomes for individuals with hip dysplasia, at every stage of life.