Introduction and Aims: Greater trochanteric pain syndrome (GTPS) refers to pain in and around the lateral hip. This condition, previously classified as trochanteric bursitis also shows tendinopathic changes in Gluteus Minimus/Medius. Central nervous system sensitization has been identified in other tendinopathies, which may explain the chronic and intractable pain often associated with tendinopathy1. No studies have examined if central sensitization (CS) is a feature of GTPS. This cross-sectional case-control study aimed to determine if features of CS exist in people in GTPS.
Methods: Patients with unilateral GTPS were recruited from an acute hospital in Dublin, Ireland. Age and gender-matched symptom-free controls were recruited from an academic institution in Dublin. The following CS measures were used: self-report Central Sensitisation Inventory (CSI) and pain pressure thresholds (PPTs) at local and remote sites in upper and lower limbs using pressure algometry. Other outcomes included the VISA-G (GTPS-specific disability), pain severity (NPRS) and hip abductor and adductor strength using a hand-held dynamometer. Differences between between cases and controls and CS/Non CS cases were analysed using Mann-Whitney U tests.
Results
18 cases (83% female) were matched to 18 controls (83% female). Eight (44.4%) of the GTPS group had CS based on CSI cut-off (>40). Cases and controls differed significantly in PPT, CSI and strength measures in both affected and non-affected sides. Comparisons (CS vs non-CS in GTPS group) showed significant differences only in greater trochanter PPTs. There were no significant differences in BMI, VISA-G. PPT of UL or LL remote sites or Hip Abductor and Adductor strength between CS and non-CS patients.
Conclusion
This study provides preliminary evidence of CS in a subgroup of people with unilateral GTPS. PPTs at both local and remote sites were higher bilaterally in those with GTPS compared to controls. Strength deficits also occurred bilaterally in hip adductor and abductor muscles. CS did not appear to be related to age, BMI, strength or disability. These results require future validation and should consider other factors such as psychosocial influences.
References Plinsinga ML et al. Evidence of Nervous System Sensitization in Commonly Presenting and Persistent Painful Tendinopathies: A Systematic Review. JOSPT 2015; 45, 11, 864-75.
Ethics approval gained from RCSI and Connolly Hospital Research ethics committees.
