PREDICTING ACUTE POSTOPERATIVE PAIN BY PRESSURE PAIN THRESHOLD AND SALIVA CORTISOL LEVELS IN MALE PATIENTS UNDERGOING KNEE ARTHROSCOPY
Eva Szuchy Kristiansen, Louise Skou Nielsen, Siv Sofie Christensen, Sten Rasmussen and Parisa Gazerani
Orthopaedic Surgery Department, Aalborg University Hospital, Denmark
Department of Biomedicine, Faculty of Medicine, Aalborg University, Denmark

Background and aims: The management of acute postoperative pain is still a major challenge for clinicians as 30% of patients who undergo surgery report moderate to severe pain in the acute postoperative period. Therefore, it is important to identify patients with increased risk of developing acute postoperative pain. The goal is to achieve this through easily accessible non-invasive methods applied preoperatively. This study was designed to investigate if pressure pain threshold (PPT) and saliva cortisol levels could predict acute postoperative pain in male patients undergoing elective knee arthroscopy.
Methods: 24 men (18-48 years) who underwent elective knee arthroscopy participated in 3 consecutive session: Prior to surgery, 1.5 hours after surgery, and one day after surgery. PPT was measured on the operated and on the control knee on eight test sites with a handheld algometer. Saliva cortisol samples were collected with passive drooling technique and analyzed by enzyme-linked immunosorbent assay (ELISA). ANOVA test were used to statistical analysis. P<0.05 was considered significant.
Results: Mechanical sensitivity was evident following knee arthroscopy (p<0.05). Preoperative PPT and saliva cortisol concentrations did not show a correlation to acute postoperative pain (p>0.05). However, a tendency was apparent that patients with lower PPT values on the operated knee preoperatively had higher pain intensity postoperatively.
Conclusions: Following knee arthroscopy the operated knee became sensitized to mechanical stimuli. This preliminary study showed that PPT and saliva cortisol levels measured preoperatively might not be suitable predictive factors of acute postoperative pain in male patients undergoing knee arthroscopy.

PRESSURE PAIN THRESHOLD AND SALIVARY LEVELS OF CORTISOL IN PATIENTS UNDERGOING KNEE ARTHROSCOPY