Navigating Hip Dysplasia – Reclaiming Stability

What is Hip Dysplasia?

Hip dysplasia can result in chronic pain and early-onset osteoarthritis if untreated. Affecting 3–5% of the general population, it disproportionately impacts females and is frequently associated with a family history of hip disorders. Its subtle clinical signs and often normal findings on initial imaging contribute to its frequent misdiagnosis and delayed treatment. ^1,2

It is a condition that affects the anatomy of the hip. Defined by a shallow acetabulum that fails to adequately support the femoral head, hip dysplasia causes joint instability and abnormal mechanical stress. These biomechanical imbalances lead to labral tears, cartilage degeneration, and progressive joint damage. Timely diagnosis and appropriate management are essential to preventing long-term disability and preserving joint function in this active population. ^1,2

Clinical History 

Sarah, an active 24-year-old female marketing professional with a passion for running, presented with atraumatic gradual onset left groin pain, which she noticed during her half-marathon training. Over the course of several months, the pain progressively worsened, becoming more pronounced during and after runs, as well as during prolonged sitting at her desk job. She also experienced a vague catching and popping sensation and noted discomfort on the lateral aspect of the left hip.

Her medical history was unremarkable, with no prior significant hip injuries or congenital diagnoses. However, she had a family history of osteoarthritis and Sarah is concerned regarding doing damage to her hip with activity.

Past Medical History  

Nil   

Drug History  

Nil 

Exercise History 

Recreational runner with aspirations to complete a half marathon, also enjoys weekly Pilates. Previously competed in gymnastics as a teenager 

Examination: 

Sarah’s clinical hip examination revealed:

• Observation: Mild antalgic gait
• Functional Assessment: Difficulty maintaining single-leg stance on the left side without discomfort or compensatory hip drop
• Neurovascular: Intact, with no signs of neurovascular compromise
• Palpation: No abdominal masses, or lumps felt in the femoral triangle. 
• Beighton score: 6/9
• Special Tests:
  • Positive FADIR (Flexion, Adduction, Internal Rotation) test eliciting pain
  • Prone Instability test positive 

Bedside Diagnostic Ultrasound 

• Anterior Hip: No Hip joint effusion seen, Normal appearance of iliopsoas, no snapping psoas elicited on dynamic testing, Normal appearance of rectus femoris direct and indirect tendon. Normal appearances of the femoral artery and vein (no formal doppler scan performed at this stage).
• Lateral Hip: No greater trochanteric bursa seen and normal appearance of gluteus medius tendons. 

Differential Diagnosis 

Stress Fracture

In Sarah’s case, a femoral stress fracture is a key consideration given her history of progressive, atraumatic groin pain during running and weight-bearing activities. Stress fractures can result from repetitive loading of the femoral neck, particularly in runners who increase their training volume significantly. Additionally, as a young, active woman she is at a higher risk, especially if there are contributing factors such as relative energy deficiency, insufficient caloric intake, or hormonal irregularities.^2,3 

While bedside ultrasound has excluded other soft tissue causes, it cannot reliably detect bone stress injuries. Therefore, cross-sectional imaging, specifically MRI, is warranted to evaluate for a potential femoral stress fracture and guide appropriate management.^2,3

You can listen to our LBSM podcast on a case presentation of hip stress fracture here

Femoroacetabular Impingement 

Femoroacetabular impingement (FAI) is an important differential to consider, particularly given Sarah’s history of localised, activity-related groin pain and mechanical symptoms like catching and popping. FAI occurs when variations in hip anatomy—such as cam morphology (excess bone at the femoral head-neck junction) or pincer morphology (excess bone along the acetabular rim)—lead to excessive contact between the femoral head and acetabulum during certain movements.^2,3

Repetitive impingement can damage the labrum and cartilage, potentially causing persistent groin pain and predisposing to early osteoarthritis. Sarah’s sharp, localised anterior groin pain, exacerbated by activity, aligns with the characteristic presentation of FAI. Further imaging, including X-Ray , would be necessary to confirm the diagnosis and MRI to assess for associated labral or cartilage injury.^2,3

Snapping Hip Syndrome 

Snapping hip syndrome is another condition to consider. This condition arises when tendons, such as the iliotibial band over the greater trochanter or the iliopsoas tendon over anterior hip structures, snap over bony prominences during movement. The resulting snapping or clunking sensation, sometimes accompanied by an audible noise, can be reproduced on demand by the patient.^2,3

Athletes and dancers are particularly prone to this condition due to repetitive hip motions, making it a relevant consideration for Sarah, given her active lifestyle and history of gymnastics. While snapping hip syndrome is often benign, it can lead to irritation or bursitis, causing additional discomfort. Sarah’s clinical findings and ultrasound results, however, do not indicate snapping of the iliopsoas, making this a less likely differential in her case.^2,3

Greater Trochanteric Pain Syndrome

Greater trochanteric pain syndrome (GTPS) is a differential to consider for Sarah’s hip pain, though her clinical presentation makes it less likely. GTPS involves inflammation of the bursa over the greater trochanter or tendinopathy of the gluteus medius and minimus, often resulting from overuse, trauma, or postural abnormalities. It typically manifests as isolated lateral hip pain, accompanied by tenderness over the greater trochanter.^2,3

In Sarah’s case, the absence of tenderness in this region, along with normal ultrasound findings for gluteal tendons and bursal structures, makes GTPS an unlikely cause. While her active lifestyle could predispose her to this condition, her anterior groin pain and mechanical symptoms align more closely with intra-articular pathologies, further lowering the suspicion for GTPS.^2,3

Investigations: 

X-Ray

Plain X-ray was performed, and Lateral Central Angle was calculated (details below)

Image 1: Cropped AP pelvis radiographs of demonstrates reduced lateral acetabular coverage and calculator lateral central angle of 20 degrees 

Reproduced under Creative Commons Attribution-Noncommercial-NoDerivs 3.0 License   Link: https://radsource.us/developmental-dysplasia-of-the-hip/

MRI 

Image 2: The coronal fat-suppressed proton density-weighted image (left) demonstrates increased thickness of the superolateral acetabular cartilage (arrowheads). The lateral centre edge angle measures 20 degrees. The axial oblique image (right) demonstrates a tear across the base of the anterior labrum (arrow).

Reproduced under Creative Commons Attribution-Noncommercial-NoDerivs 3.0 License  Link: https://radsource.us/developmental-dysplasia-of-the-hip/

Diagnosis: Hip Dysplasia

A diagnosis of hip dysplasia with an associated labral tear was confirmed. Initial management focused on activity modification, tailored analgesia for symptom relief, and a structured, physiotherapy-guided rehabilitation program to improve joint stability and function. A multidisciplinary team (MDT) approach was employed to assess the need for additional interventions, including diagnostic or therapeutic injections, as well as potential surgical options if conservative measures proved insufficient.

Discussion And Key Points  

• Hip dysplasia is characterised by structural instability caused by inadequate acetabular coverage. 
• Frequently underdiagnosed or identified late, if left untreated this condition can result in progressive damage, including labral tears, chronic pain and early-onset osteoarthritis,
• Physical examinations such as the FADIR (Flexion, Adduction, Internal Rotation) test and the prone instability test are valuable tools in identifying hip dysplasia.
• Primary diagnostic imaging includes X-rays focusing on the lateral centre-edge angle 
• Management:
  • Conservative: Physiotherapy plays a central role to improve joint stability, Lifestyle modifications and targeted pain-relief strategies, including injections, can be employed to manage symptoms.
  • Surgical: Peri-acetabular osteotomy (PAO) for reshaping the hip joint, with good outcomes in delaying osteoarthritis in appropriate candidates.

Hip Anatomy 

Hip dysplasia is defined by structural abnormalities of the hip joint, most notably a shallow or misaligned acetabulum that fails to adequately support the femoral head. This deficiency results in joint instability and increased mechanical stress, particularly during weight-bearing activities, ultimately compromising hip function.^2,4

Key Anatomical Features

1. Acetabulum:

The acetabulum often lacks sufficient depth or proper orientation, leading to inadequate coverage of the femoral head. This predisposes the joint to instability and excessive shearing forces, especially during activities involving hip flexion and rotation.^2,4

2. Labrum:

The labrum, a fibrocartilaginous ring encircling the acetabular rim, provides additional stability in the absence of adequate bony support. In dysplastic hips, the labrum hypertrophies to compensate for increased load, but over time, this can result in labral tears, a common source of pain and dysfunction.^2,4

3. Muscles and Ligaments:

Stability of the hip joint relies on robust musculature, such as the gluteus medius and minimus, and strong ligaments, including the iliofemoral, ischiofemoral, and pubofemoral ligaments. In dysplasia, these structures often become overworked or lax, further exacerbating joint instability and dysfunction.^2,4

Patient Presentation: History and Symptoms

Hip dysplasia often presents with subtle, insidious symptoms that contribute to delayed diagnosis. Patients commonly experience groin pain, which may radiate to the lateral hip or buttocks. This pain is typically activity-related, worsening with walking, running, or prolonged sitting, and is often relieved by rest. Mechanical symptoms such as clicking, catching, locking, or a sensation of instability are also frequently reported.^3,5

The condition is more prevalent in young females, particularly those with a history of hypermobility or a family history of hip disorders. Misdiagnosis is common, with symptoms often attributed to conditions such as gluteal tendinopathy or hip flexor-related pain. This overlap in presentation highlights the importance of thorough clinical evaluation and timely recognition to prevent progression and long-term complications.^3,5 

Examination Techniques

Physical examination remains a cornerstone for the clinical diagnosis of hip dysplasia, focusing on eliciting signs of instability and impingement:

1. FADIR Test (Flexion, Adduction, and Internal Rotation): A positive result, indicated by reproduction of the patient’s symptoms, suggests intra-articular pathology such as labral damage. Studies report a high prevalence of FADIR positivity in dysplastic hips​^4,6
2. Prone Instability Test: This assesses joint stability under load. Increased mobility or discomfort during this test suggests instability, a hallmark of dysplasia​^4,6
3. Beighton Scoring System: This evaluates generalised hypermobility, which is often associated with dysplasia. A higher score indicates ligamentous laxity that may contribute to joint instability^4,6

Role of Imaging in Diagnosing Hip Dysplasia

Imaging plays a pivotal role in diagnosing hip dysplasia, offering both qualitative and quantitative assessments of the structural abnormalities. It provides crucial information to confirm clinical findings and guide treatment decisions.

Plain Radiography

Plain radiographs are the first-line imaging modality for diagnosing hip dysplasia due to their accessibility and utility in evaluating acetabular and femoral head alignment.

• Lateral Center-Edge Angle (LCEA): The LCEA, measured on anteroposterior (AP) pelvic radiographs, it is a metric for assessing acetabular coverage of the femoral head. If the value is <25° Then dysplasia should be considered.^4,6  
• Acetabular Index (AI): Also known as the sourcil angle, calculated at the angle of the weightbearing zone of the socket. A value >10° indicates poor acetabular orientation, commonly seen in dysplasia.^4,6

Image 3 Lateral Centre Angle and Sourcil Angle

Adapted from: Soper-Doyle, H., & Sharp, M.-J. (2024). Hip Dysplasia in Teenagers & Young Adults: A Patient’s Guide. Royal National Orthopaedic Hospital. Available from: www.rnoh.nhs.uk. 

MRI 

Magnetic Resonance Imaging (MRI) is particularly useful for evaluating soft tissue structures and detecting associated intra-articular pathology:

• Labral Pathology: Dysplastic hips commonly present with labral hypertrophy or tears due to compensatory overuse. MRI arthrograms can highlight contrast extravasation from labral tears, offering greater diagnostic specificity. ^5,6
• Cartilage Assessment: MRI can detect early chondral wear or damage in the acetabulum and femoral head, critical for understanding disease progression​. ^5,6

Management of Hip Dysplasia

Conservative Management

The conservative management of hip dysplasia focuses on symptom relief, joint stabilisation, and preventing further degeneration. Physiotherapy is a cornerstone of treatment, targeting core strength, posture correction, and muscle balance to optimise hip stability. 

Strengthening the hip abductors, extensors, and rotators enhances dynamic joint support, while proprioception training improves neuromuscular control. These measures are particularly important for patients with concurrent hypermobility, where movement patterns require retraining to minimise joint stress. Activity modification is also essential, with patients advised to avoid positions or activities that aggravate symptoms, such as deep squats or prolonged sitting. ^4-6

Lifestyle

Lifestyle adjustments complement rehabilitation efforts. Having good nutrition and maintaining a healthy weight helps to reduce mechanical loading on the hip joint, while gradual reintroduction of activities under physiotherapy supervision ensures safe progression and reduces the likelihood of symptom recurrence. 

Pain Management

For pain management, non-steroidal anti-inflammatory drugs (NSAIDs) are commonly prescribed, and corticosteroid injections may provide temporary relief for significant inflammation or labral irritation. However, repeated injections are avoided to mitigate potential cartilage damage, and they are used primarily to facilitate participation in rehabilitation programmes.^4-6

Education

Patient education plays a critical role in the success of conservative management. Providing patients with an understanding of the biomechanical challenges posed by dysplasia empowers them to engage actively in their recovery. Addressing psychological concerns—such as fear of movement or pain-related anxiety—can further enhance treatment outcomes. ^4-6

Surgical Management

Surgical intervention is considered for patients with significant structural abnormalities or symptoms unresponsive to conservative measures. Periacetabular osteotomy (PAO) is the surgical treatment of choice, aiming to realign the acetabulum to improve femoral head coverage and joint stability. This procedure has demonstrated efficacy in delaying osteoarthritis progression and improving pain and function in appropriately selected candidates. ^4-7

Conclusion

Hip dysplasia is a complex condition characterised by structural instability that, if left untreated, can lead to chronic pain, functional limitations, and early-onset osteoarthritis. Early recognition and accurate diagnosis are crucial to prevent progression and optimise patient outcomes. A multidisciplinary approach is key, combining conservative measures such as physiotherapy, lifestyle modifications, and pain management with surgical interventions like periacetabular osteotomy in appropriate cases. Patient education and engagement are fundamental to ensuring adherence to treatment plans and achieving long-term success. By tailoring management strategies to the individual, clinicians can significantly improve quality of life and preserve hip function for the future.

Reference:

1. Dick, Alastair G., Jonathan M. Houghton, and Marcus JK Bankes. “An approach to hip pain in a young adult.” British Journal of Sports Medicine 55.5 (2021): 290-294. 
2. Wilkin GP et al. A Contemporary Definition of Hip Dysplasia and Structural Instability. The Journal of Arthroplasty. 2017 
3. Reiman, Michael P., et al. “Consensus recommendations on the classification, definition and diagnostic criteria of hip-related pain in young and middle-aged active adults from the International Hip-related Pain Research Network, Zurich 2018.” British journal of sports medicine 54.11 (2020): 631-641.
4. Soper-Doyle, H., & Sharp, M.-J. (2024). Hip Dysplasia in Teenagers & Young Adults: A Patient’s Guide. Royal National Orthopaedic Hospital. Available from: www.rnoh.nhs.uk. 
5. Nunley, Ryan M., et al. “Clinical presentation of symptomatic acetabular dysplasia in skeletally mature patients.” JBJS 93.Supplement_2 (2011): 17-21. 
6. Reiman, Michael P., et al. “Accuracy of clinical and imaging tests for the diagnosis of hip dysplasia and instability: a systematic review.” journal of orthopaedic & sports physical therapy 49.2 (2019): 87-97.
7. Jacobsen, Julie Sandell, et al. “Patient-reported outcome and muscle–tendon pain after periacetabular osteotomy are related: 1-year follow-up in 82 patients with hip dysplasia.” Acta orthopaedica 90.1 (2019): 40-45.