Likely Causes of Persistent Knee Pain After Stair Step in hEDS
In someone with hEDS experiencing persistent knee pain after taking a stair step, the most likely causes are patellar subluxation or dislocation, ligamentous microtrauma from joint instability, and chronic pain amplification from connective tissue laxity—all stemming from the fundamental collagen abnormality that makes joints hypermobile and prone to injury with minimal trauma. 1
Primary Musculoskeletal Mechanisms
The knee is particularly vulnerable in hEDS patients due to several interconnected factors:
Patellar instability is extremely common, with recurrent subluxations or dislocations affecting the patella as one of the most frequently involved joints in hEDS 1. A simple stair step can trigger patellar tracking abnormalities that persist.
Ligamentous laxity and microtrauma occur because the connective tissue in hEDS is softer and less stiff than in healthy individuals 2. Each step creates repetitive microtrauma to already compromised ligaments and joint capsules, leading to persistent inflammation and pain.
Joint hypermobility confirmed by Beighton scoring (≥5/9 in adults under 50) predisposes to abnormal biomechanics during stair climbing 1. The knee may hyperextend or move through excessive range of motion, straining periarticular structures.
Chronic Pain Amplification
Beyond the acute injury, hEDS patients experience disproportionate and persistent pain:
Central pain sensitization is a hallmark feature, where 43% of hEDS patients suffer from severe pain that persists well beyond the initial trigger 3. The nervous system in hEDS amplifies pain signals, making a minor stair-step injury feel catastrophic and last indefinitely.
Fibromyalgia overlap is common in hEDS patients, particularly those with concomitant POTS 2. This creates a chronic pain state where localized knee pain becomes part of a broader pain syndrome.
Thoughts of helplessness significantly increase the likelihood of severe pain in hEDS patients 3. The psychological response to injury matters enormously in this population.
Associated Complications to Consider
Several other factors may contribute to or complicate the knee pain:
Pelvic floor dysfunction and altered gait mechanics are highly prevalent in hEDS 4, which can create compensatory movement patterns that overload the knee joint during stair climbing.
Autonomic dysfunction (POTS) affects up to 37.5% of hEDS patients 2. Orthostatic intolerance with lightheadedness and weakness 1 may cause altered proprioception or balance during stair navigation, leading to abnormal loading of the knee.
Mast cell activation triggered by mechanical stimuli 2 could theoretically be activated by the physical stress of stair climbing, contributing to localized inflammation and pain persistence through histamine and cytokine release.
Critical Pitfalls to Avoid
Do not dismiss persistent pain as "just hypermobility"—while the underlying mechanism is connective tissue laxity, the pain is real, disabling, and requires active management 3, 5.
Do not assume imaging will show the problem—ligamentous injuries and subluxations in hEDS often reduce spontaneously and may not be visible on static imaging. The diagnosis is clinical.
Do not overlook diagnostic delay—delayed recognition of hEDS as the underlying cause increases the likelihood of severe pain 3. If this patient doesn't have a confirmed hEDS diagnosis, pursue it now using the 2017 criteria 4.
Immediate Assessment Priorities
When evaluating this patient, specifically look for:
- History of patellar "giving way" or feeling the kneecap shift during the stair step, suggesting subluxation 1
- Beighton score assessment if not previously documented 1
- Postural vital signs to screen for POTS (heart rate increase ≥30 bpm within 10 minutes of standing) 4, 1, as this may have contributed to the initial injury
- Pain severity and functional impact using validated scales, as two-thirds of hEDS patients have high mobility disability 3
Management Approach
- Physical therapy focused on proprioceptive training and strengthening is the cornerstone, as preventing joint injury is a central goal 6, 5
- Psychological support to address pain catastrophizing and helplessness, which directly predict pain severity 3, 5
- Consider patellar bracing or taping during activities to provide external stability the connective tissue cannot provide
- Multimodal pain management may include trigger point injections or peripheral nerve blocks if conservative measures fail 5