Prevention of Posttraumatic Osteoarthritis After Acute Intraarticular Fractures

Osteoarthritis (OA) affecting one in eight individuals and is the main reason for chronic pain and disability worldwide. The main cause for OA development is joint-affecting trauma and risk factors have primarily been associated to previous biomechanical treatment. Therefore, the principle of current fracture treatment is anatomical reconstruction of the joint surface combined with functional and adequate aftercare. However, despite correct restoration of anatomy and application of sufficient physiotherapy, the risk of posttraumatic OA remains as high as 40%.

Joint trauma initiates an inflammatory cascade leading to synovial catabolism and cartilage degradation, a fact, which to date has been ignored in standard therapy. Unfortunately, due to the lack of blood supply, cartilage regenerates much less efficient compared to bone. Previous studies suggest that the synovial biochemical milieu may be of decisive importance for chondrocyte and cartilage survival or degeneration. The investigators therefore hypothesize, that protecting cartilage and chondrocyte by inhibiting the post-injury inflammatory cascade, might contribute to durable successful results in fracture therapy. The purpose of this project is to identify the biomarkers in the joint space after an intra-articular ankle fracture and to evaluate how these biomarkers affect the short- and mid-terms clinical outcomes. As secondary outcomes we evaluate how fracture classification and reduction affect clinical outcomes and physical activity after surgery. In specific, we intend to answer the following research questions:

Study 1: Are there differentially regulated biomarkers in joint space in patients with and without an intra-articular ankle fracture?

Study 2: Do the identified biomarkers found in intra-articular ankle fracture correlate with short- and middle term clinical symptoms after surgery?

Study 3: Does fracture classification and fracture reduction effect clinical outcomes and physical activity?

Method

This study is approved by The National Committee on Health Research Ethics (S-20170139) and The Danish Data Protection Agency (17/28505). Patient recruitment is carried out in the Department of Orthopedic Surgery at Odense University Hospital, Svendborg, while biomarker analyses mainly take places in Department of Neurobiology Research.

All patients diagnosed with intra-articular ankle fracture hospitalized in Odense University Hospital, Svendborg will be recruited to this study.

Prior to surgery synovial fluids are collected from the fracture ankle and contralateral ankle of the same patient. The patient is lying in supine position and the disinfection of both ankles will follow our department's guidelines. A 1.5 x 50 mm needle is inserted in the joint line using the anteromedial or anterolateral approach. Once the needle is in the joint space, a volume of 5.0 ml isotonic saline will be injected in the joint place and mixed before retraction. All patients will have antibiotic coverage prior to surgery to minimize the risk of infection. This procedure is mainly performed by two surgeons (TP and HS), who have great experience in this procedure. In case other surgeons collect the sample, X-ray may be used for assistance. Synovial fluid will be collected, transferred in a 10 ml glass, and within 2 hours transported to the Department of Clinical Biochemistry and Pharmacology for centrifugation and storage at minus 80 degrees celsius. At the end of each month all samples will be transferred in dry ice to the Department of Molecular Endocrinology to be stored in liquid nitrogen. Blood samples will also be collected in Ethylenediaminetetraacetic acid (EDTA) glasses for comparison.

For the discrimination between the fracture and the anterolateral healthy joint, a proteomics analysis is used to identify the classical pro-inflammatory cytokines and the cytokines involving in the extracellular breakdown and cartilage degeneration. For that purpose, a custom multi-ELISA Plex including (IFN-γ, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-13, tumor necrosis factor (TNF-α), IL-1α, TNF-β, basic fibroblast growth factor (bFGF), IL-1RA), Human matrix metalloproteinase (MMP) 3-Plex Ultra-Sensitive Kit, U-PLEX TGF-β Combo, Aggrecan and CTX-2, will be performed.

The following epidemiological parameters will be recorded: age, sex, body mass index, classification of injury according to Arbeitsgemeinschaft für Osteosynthesefragen (AO) standards, allowed weight bearing, aftercare follows the Odense guidelines with a static walker. All patients will be evaluated at 3 and 12 months post injury according to the following clinical parameters:

Pain (visual analog scale), return to work (days), swelling (measurement of circumference at malleoli (cm)), ankle X-ray, 3D-rotational tomography, 7 days activity tracking and validated scores (the American Orthopedic Foot and Ankle Score (AOFAS), the Foot Function Index - DK (FFI.DK), the Euroqol 5D questionnaire (EQ5D).To reach a power of 80 %, we include 62 patients in our study. Because no previous studies have compared level of pro-inflammatory cytokines with clinical scores, the power estimation is based on a very high standard deviation, loss of follow-up and clinical importance. The investigators plan to perform an interim analysis, when a number of 40 patients is reached.