What could cause my hip to give way when climbing or stepping onto a stool, and how should I manage it?

Hip Instability with Mechanical Giving Way

Your hip giving way when climbing stairs or stepping onto a stool is most likely caused by hip instability, which requires clinical evaluation with specific instability testing, plain radiographs, and consideration of advanced imaging if conservative management fails.

What's Causing This

The sensation of your hip "giving way" during weight-bearing activities like stair climbing represents a mechanical instability pattern. This occurs when:

• Capsular laxity allows excessive femoral head translation within the acetabulum 1, 2
• Acetabular undercoverage (dysplasia or borderline dysplasia) creates insufficient bony support 3
• Labral damage compromises the suction seal that normally stabilizes the hip 1
• Hip abductor weakness prevents proper pelvic stabilization during single-leg stance 4, 5

The giving-way sensation specifically during stair climbing is a classic mechanical symptom that worsens with activity—a hallmark of structural hip problems 4.

Clinical Evaluation You Need

Key Physical Examination Findings to Assess

For instability specifically:

• AB-HEER test (Abduction-Hyperextension-External Rotation) and HEER test provide the highest accuracy for detecting instability 1
• Prone instability test has high specificity to confirm instability when positive 1, 2
• PART test (Prone Apprehension Relocation Test) correlates with anterior acetabular undercoverage 4
• Trendelenburg gait indicates hip abductor insufficiency, commonly associated with dysplastic hips 4, 5

General hip screening:

• FADIR test (Flexion-Adduction-Internal Rotation) is recommended as the primary screening test for all hip-related pain, though it has limited specificity 3

Imaging Protocol

Start with plain radiographs 3:

• AP pelvis view
• Lateral femoral head-neck view (Dunn, frog-leg, or cross-table)

These assess for:

• Lateral center-edge angle (LCEA): <20-25° indicates dysplasia 2
• FEAR index for borderline dysplasia risk stratification 1
• Acetabular inclination (Tönnis angle)
• Cliff sign

Advance to MRI/MRA or CT arthrogram when 3:

• Conservative treatment fails
• Surgery is being considered
• Need to assess labral, cartilage, or ligamentum teres pathology

Critical caveat: Never diagnose based on imaging alone—incidental findings are common in asymptomatic people 3. Diagnosis requires the combination of symptoms + clinical signs + imaging.

Management Algorithm

Initial Conservative Treatment

1. Physical therapy focusing on hip abductor strengthening 6

   • Addresses the Trendelenburg pattern and pelvic instability
   • Moderate strength recommendation for mild-to-moderate hip symptoms

2. NSAIDs when not contraindicated 6

   • Strong recommendation for symptomatic relief
   • High quality evidence

3. Acetaminophen as alternative 6

   • Consensus option when NSAIDs contraindicated

4. Intra-articular corticosteroid injection 6

   • Moderate recommendation for transient symptom relief
   • Can be considered if oral medications insufficient

When Conservative Treatment Fails

For confirmed instability with borderline dysplasia:

• Both hip arthroscopy and periacetabular osteotomy (PAO) improve outcomes when selection is phenotype-guided 1
• PAO shows lower conversion to total hip arthroplasty when undercoverage is the primary driver 1

For capsular laxity without significant bony abnormality:

• Arthroscopy with labral preservation and complete capsular closure improves outcomes and survivorship compared to non-closure 1
• Capsular plication addresses the soft-tissue instability 7

Common Pitfalls to Avoid

• Don't rely on FADIR test alone—it screens for hip problems generally but doesn't differentiate between impingement and instability 3
• Don't over-interpret MRI findings—asymptomatic labral tears are common 3
• Don't ignore the gait pattern—Trendelenburg gait is a visible sign of the biomechanical problem 4, 5
• Don't assume all hip pain is impingement—instability often overlaps with or mimics femoroacetabular impingement syndrome 1, 2

Bottom Line

Your giving-way episodes during stair climbing warrant evaluation for hip instability. Start with targeted physical examination (AB-HEER, prone instability tests) and plain radiographs. If you have borderline dysplasia (LCEA 20-25°) or capsular laxity, structured physical therapy targeting hip abductors is the first-line treatment. Surgical options exist if conservative measures fail after adequate trial, with the specific procedure depending on whether your instability is primarily bony (consider PAO) or soft-tissue based (arthroscopy with capsular management).