Predictors of Chronic Pain Following Total Knee Replacement in Females and Males: An Exploratory Study

Abstract

Aim: This study explored whether nociceptive (NS) and autonomic nervous system (ANS) dysregulation and psychological distress were predictive of pain 6 months after primary total knee replacement. Patients & methods: ANS and NS regulation, psychological distress and self-reported pain, stiffness and function were evaluated preoperatively in 56 patients. Pain severity measured 6 months after surgery was used as the primary outcome in an analysis of covariance model. Results: The data of 47 patients (85.5%) could be analyzed. Postoperative pain severity 6 months after surgery was significantly associated with reduced heart rate variability and tended to be related to a lower conditioned pain modulation effect, but the latter only in females. Conclusion: Due to the small sample size the results must be interpreted with caution. A dysregulation of ANS and NS may be predictive of pain severity 6 months after total knee replacement. The impact of the conditioned pain modulation effect could be sex specific.

KEYWORDS:

• chronic postsurgical pain
• conditioned pain modulation effect
• heart rate variability
• pain catastrophizing
• temporal summation
• total knee replacement

Acknowledgements

The authors would like to thank S Haug, Chair of Mathematical Statistics (Klüppelberg), Technical University Munich for his support with the statistical analysis.

Furthermore, this research project would not have been possible without the support of many people. The authors wish to express their gratitude to the colleagues from our cooperating hospitals for their valuable support during the research process: B Michel and M Kley (endogap Kinik für Gelenkersatz, Klinikum Garmisch-Partenkirchen). R Eisenhart-Rothe and N Harrasser (Klinik und Poliklinik für Orthopädie und Sportorthopädie, Klinikum rechts der Isar, Technische Universität München). S Horn (Krankenhaus Barmherzige Brüder München, Abteilung Orthopädie und Unfallchirurgie).

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

No writing assistancewas utilized in the production of this manuscript.

Ethical approval

The study was approved by the ethics committee of the faculty of medicine, Technical University Munich (TUM; project number: 5498/12) and is indexed within the German Clinical Trials Register (DRKS00005147).