Comparative Analysis of Upper and Lower Extremity Complex Regional Pain Syndrome

Research Type: Level 3 - Retrospective cohort study, Case-control study, Meta-analysis of Level 3 studies Introduction/Purpose: Complex regional pain syndrome (CRPS) is thought to occur as a hyperinflmamatory response after trauma. Symptoms include derangements in sensation, motor function and edema, including hyperesthesia, temperature asymmetry and decreased range of motion. Previous data suggest that CRPS in the lower extremity (LE) may manifest differently compared to upper extremity (UE) CRPS, although there are few studies directly comparing UE versus LE CRPS. Therefore, we sought to compare the patient demographics, injury characteristics and resolution of UE and LE CRPS with the hypotheses that CRPS would occur in the UE and LE equally in response to surgical or nonsurgical intervention. Methods: A retrospective chart review was conducted of CRPS patients from 2013-2023 at a single academic medical center. Patient demographics were collected, including age, gender, smoking, co-morbidities and medications. Mechanism of injury was collected, along with CRPS symptoms, operative versus non-operative treatment and whether improvement was noted over time. Statistical analysis was conducted using Prism statistical software. P< 0.05 was the cut-off for significance. Results: 117 patients had UE versus 81 patients with LE CRPS. 69% of UE and 67% of LE CRPS patients were female (p=0.88). 27.4% of UE and 24.7% of LE CRPS patients were worker’s compensation (p=0.74). 30.2% of UE and 27.2% of LE CRPS patients took opioids (p=0.75). 26.7% of UE and 33.3% of LE CRPS patients took psychiatric medications (p=0.33). 16.4% of UE and 11.1% of LE CRPS patients took both opioid and psychiatric medications (p=0.41). 33.3% of UE and 30.9% of LE CRPS developed CRPS after surgery (p=0.76). The average time from injury or surgery to CRPS was 11.4 months for UE and 9.7 months for LE CRPS (p=0.86). 53.8% of UE and 44.4% of LE CRPS patients improved over time (p=0.46). Conclusion: Most patients developed CRPS after a non-operative injury with no differences between UE and LE CRPS patients in terms of the demographic or injury characteristics. However, most CRPS patients were female and >25% of patients were either taking opioid or psychiatric medications. With the increased proportion of opioid use, psychiatric medications and worker’s compensation claims in the CRPS population compared to the general population, these data highlight the relationship between substance use, psychiatric co-morbidities and social stressors on CRPS, suggesting that an interdisciplinary approach that includes the orthopedist, along with psychiatrists and social services could improve patient outcomes.