Changes in pain catastrophization and neuropathic pain following operative stabilisation for patellofemoral instability: a prospective cohort with 12-month follow-up

Purpose
To determine the prevalence and change in neuropathic pain or pain catastrophizing before and 12 months following patellar stabilisation surgery for patellofemoral instability.

Methods
We conducted a prospective clinical audit within a UK NHS orthopaedic surgical centre. Data from 84 patients with patellofemoral instability requiring stabilisation were analysed. Fifty percent (42/84) underwent MPFL reconstruction alone, and 16% (13/84) had both trochleoplasty and MPFL reconstruction. Neuropathic pain was assessed using painDETECT score. Pain catastrophizing was assessed using the Pain Catastrophizing Score. The Norwich Patellar Instability (NPI) Score and Kujala Patellofemoral Disorder Score were also routinely collected pre-operatively and one year post-operatively.

Results
At 12 months post-operatively there was a statistically significant reduction in mean Pain Catastrophizing Scores (18.9–15.7; p < 0.02), but no change in mean painDETECT scores (7.3–7.8; p = 0.72). There was a statistically significant improvement in NPI scores (90.2–61.9; p < 0.01) and Kujala Patellofemoral Disorder Scores (48.7–58.1; p = 0.01). The prevalence of pain catastrophizing decreased from 31% pre-operatively to 24% post-operatively, whereas the prevalence of neuropathic pain remained consisted (10–11%).

Conclusions
Neuropathic pain and catastrophizing symptoms are not commonly reported and did not significantly change following patellofemoral stabilisation surgery. Whilst low, for those affected, there remains a need to intervene to improve outcomes following PFI surgery.