# Knee skin temperature following unicompartmental knee arthroplasty and its relationship with inflammatory indicators

## TL;DR

This study examines how knee skin temperature changes after unicompartmental knee arthroplasty and its link to inflammation.

## Contribution

The study identifies a correlation between post-surgery knee skin temperature and inflammatory markers, suggesting a normal healing response.

## Key findings

- Knee skin temperature peaked on post-operative day 3 and normalized over six months.
- Temperature changes correlated with inflammatory markers like CRP and WBC.
- Inflammatory markers returned to pre-surgery levels during follow-up.

## Abstract

Unicompartmental knee arthroplasty (UKA) effectively alleviates pain and restores function in end‐stage knee osteoarthritis. However, the relationship between post‐operative knee skin temperature and systemic inflammatory responses remains poorly characterized. This study aimed to: (1) quantify changes in knee skin temperature and temperature difference for 6 months post‐UKA, (2) analyze correlations between temperature difference and serum inflammatory markers, (3) determine whether prolonged thermal alterations represent a normal healing response or potential early warning sign of complications.

This study included 100 individuals who underwent UKA for primary osteoarthritis. Bilateral Knee skin temperatures were measured via infrared thermography preoperatively and at post‐operative days (PODs) 1, 3, 5 and months 1, 3, 6, with strict ambient temperature control (20 ± 1.0°C). Concurrently, erythrocyte sedimentation rate (ESR), white blood cell count (WBC) and serum C‐reactive protein (CRP) were assessed. Functional recovery was quantified using Hospital for Special Surgery (HSS) knee score.

A total of 100 patients participated in the study. Bilateral knee skin temperature and temperature difference peaked at POD 3 following UKA, with gradual normalization occurring over 6 months. The patient's CRP and WBC demonstrated progressive elevation until POD 3, while ESR exhibited delayed onset of increase. Subsequent measurements showed divergence in marker resolution: CRP and WBC levels initiate decline by POD 5, whereas ESR peaked at POD 5 following UKA. All inflammatory markers returned to preoperative levels during follow‐up.

The skin temperature of the operated knee showed a rapid increase on the first POD following UKA, peaked on POD 3, and gradually returned to normal levels by 6 months after UKA. Moreover, there is a significant correlation between changes in temperature difference and serum inflammatory markers. Normal surgical reaction may cause this alteration.

Level III.