Short summary

The aim of this thesis is to investigate prosthesis survival after revision of knee arthroplasties performed on the indication "pain without loosening" in Denmark. Furthermore, to analyze the analgesic consumption of the patients, to conduct a patient reported outcome measurement (PROM) by questionnaires and to validate the indication.

Rationale

Background

Each year about 8,500 knee arthroplasties are performed in Denmark, mainly due to osteoarthritis. 1,000 knee arthroplasties are revised each year, resulting in a revision burden of approximately 12%. The most frequent indications for revisions listed in the Danish Knee Arthroplasty Register (DKR) are "aseptic loosening" (~19%), "instability" (~18%), "infection" (~17%) and "pain without loosening" (~13%). The indication "pain without loosening" is not further defined and probably covers a broad range of pathologies.

20% of patients experience chronic pain after receiving a total knee arthroplasty (TKA). A metaanalysis by GN. Lewis et al. suggests preoperative pain, catastrophizing and depression as major risk factors to persistent pain after TKA. Aseptic revision knee procedures may be as safe as primary knee arthroplasty surgery, but patients revised on the "pain" indication have been found less satisfied. In the study by Petersen et al., 47% of revision patients, revised on any indication, had persistent pain afterwards, opposed to 19% in patients having a primary TKA. Baker et al. found aseptic revision knee arthroplasties less likely to improve clinical function and quality of life compared to primary TKAs. Authors from previous international studies recommend not to revise purely on the indication pain, when no obvious mechanical component can be detected preoperatively. Nevertheless, 13% of revisions performed in Denmark are performed on the indication "pain". No previous Danish study has investigated outcome after revision knee surgery performed on this indication. High re-revision risks of 30-40% have been reported after revision knee arthroplasty surgery performed due to infection. However, the re-revision risk after revision surgery performed due to the indication "pain" is unknown.

Although the high number of patients experiencing residual pain after knee arthroplasties are well known, the management thereof is undescribed. Furthermore guidelines to select patients who can benefit from a revision when the only indication is pain is non-existent. Analgesic consumption before and after primary hip and knee arthroplasty surgery has been investigated and continued and increased opioid and other analgesic use occurred in a clinically significant proportion of patients 9-12 months postoperatively. No study has investigated this in revision knee surgery and it is in particular relevant to investigate this in patients revised due to pain. When comparing DKR with national arthroplasty registers from other countries a great variety of reported data exist. Denmark is often compared to Sweden when analyzing data from national registries, but "pain without loosening" as indication for revision surgery does not exist in the Swedish register. The registers from Norway and UK have a greater variety of indications and the "pain" indication is often used as well as in Denmark.

Aim

The overall aim of this thesis is to investigate "pain without loosening" as indication for revision knee arthroplasty surgery.

Description of the cohort

All knee arthroplasty patients in Denmark undergoing revision on the indications "pain without loosening" and "aseptic loosening" in the period 1997-2017.

Data and biological material

Register data.

Collaborating researchers and departments

Department of Orthopaedic Surgery, Odense University Hospital

• Consultant, PhD, Associate Professor Martin Lindberg-Larsen

Department of Orthopaedic Surgery, Hospital of Naestved

• Senior Consultant, Associate Professor and Co-supervisor Henrik M Schrøder

Department of Orthopaedic Surgery, Copenhagen University Hospital, Hvidovre

• Senior Consultant, PhD, Professor Anders Troelsen