No abstract

Knee and hip arthroplasty are common surgeries within an aging population. Some data has suggested that knee arthroplasty is more traumatic to the body than hip arthroplasty due to the increased complexity and load bearing nature of the joint. Here, we compare the stress of the two surgeries by measuring urinary neopterin and total neopterin as biomarkers of oxidative stress and inflammation. Urinary neopterin and total neopterin (neopterin + 7,8-dihydroneopterin) levels were analysed in 28 knee and 22 hip arthroplasty patients pre- and post-operatively to determine oxidative stress and inflammation levels. Total neopterin was 31.1% higher with knee arthroplasty (p<0.05). Urinary neopterin was 32.8% higher in the knee arthroplasty group versus hips. The increase in neopterin and total neopterin following a post-surgical decrease in levels was significant in both groups. Levels of neopterin and total neopterin were varied between patients, but all increased following surgery and subsided by day 28. The increased levels of urinary neopterin and total neopterin from knee arthroplasty indicate that knee osteoarthritis and arthroplasty is a more significant trauma to the body than hip osteoarthritis and arthroplasty surgery. This is also shown by faster inflammatory resolution following hip arthroplasty.

Squeaking in ceramic-on-ceramic (CoC) total hip arthroplasty (THA) was investigated with an acoustic monitoring device to distinguish between squeaking emanating from the trunnion morse taper (TMT) connection versus the articular surface. 82 patients with implant problems scheduled for revision were selected and acoustic emissions (AE) with simple movements monitored. Five of these patients with CoC implants underwent surgery and their retrieved implant components were analyzed in vitro. In vivo recordings of all 82 patients found audible squeaks produce frequency content across the entire 0-50 kHz spectrum. Of the five CoC implants the in vivo peak frequency range of flexion/extension motions was 0.8 kHz and comparable to the range of in vitro testing (0.2 kHz). In vitro TMT connection motions were very large comparatively, producing a higher average peak frequency range of 22.5 kHz. All retrieved implants showed evidence of wear at the TMT connection. These findings suggest, the TMT connection does not directly cause audible squeaking. Wear occurring at this junction may contribute to debris which disrupt lubrication, increase friction, and produce noise. This observation supports current evidence suggesting that squeaking is from the bearing surface. Our findings are the first to demonstrate that in CoC THA the recordable noise of a hip squeak does not originate nor have contribution from the TMT connection. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1793-1798, 2017.