Association of acute inflammatory cytokines, fracture malreduction, and functional outcome 12 months after intra-articular ankle fracture-a prospective cohort study of 46 patients with ankle fractures

Abstract

Background: Several malreduction criteria have been proposed for ankle surgery, but the criteria of most importance for functional outcome remain undetermined. Furthermore, the acute inflammatory response in the ankle joint after fracture is hypothesized to result in osteoarthritis development, but no study has investigated the correlation between the levels of these inflammatory cytokines and post-surgical functional outcomes. We aimed to identify malreduction criteria and inflammatory cytokines associated with functional outcome after ankle surgery.

Methods: During surgery, synovial fluid from the fractured and healthy contralateral ankles of 46 patients was collected for chemiluminescence analysis of 22 inflammatory cytokines and metabolic proteins. The quality of fracture reduction was based on 9 criteria on plain X-rays and 5 criteria on weight-bearing computed tomography (WBCT) scans. After 3 and 12 months, we recorded scores on American Orthopedic Foot and Ankle Society (AOFAS) scale, the Danish version of Foot Function Index (FFI-DK), EQ-5D-5L index score, the Kellgren-Lawrence score, and joint space narrowing.

Results: Tibiofibular (TF) overlap (p = 0.02) and dime sign (p = 0.008) correlated with FFI-DK. Tibiotalar tilt correlated positively with joint space narrowing at 3 months (p = 0.01) and 12 months (p = 0.03). TF widening correlated with FFI-DK (p = 0.04), AOFAS (p = 0.02), and EQ-5D-5L (p = 0.02). No consistent correlations between synovial cytokine levels and functional outcomes were found at 12 months.

Conclusions: Malreduction of TF overlap, TF widening, and tibiotalar tilt were the most important criteria for functional outcome after ankle surgery. Increased inflammatory cytokine levels after fracture did not affect functional outcome at 12 months.

Trial registration: This cohort study is registered the 10th of December 2018 at ClinicalTrials.gov ( NCT03769909 ), was approved by the local committee on health ethics (The Regional Committees on Health Research Ethics for Southern Denmark: J.No. S-20170139), and was reported to the National Danish Data Protection Agency (17/28505).

Keywords: AOFAS; Clinical outcomes; FFI; Inflammation; Osteoarthritis; Quality of life; Weight-bearing CT; X-ray.

Conflict of interest statement

All authors declare that they have no competing interests.

Figures

Fig. 1

Flow diagram showing patient enrollment and study procedures

Fig. 2

Fracture reduction criteria measured on post-operative X-ray 3 months after ankle surgery. 2a Medial step-off in mortise view. 2b Posterior step-off: only included if more than 20% of the articulating surface was affected in lateral view. 2c Tibiotalar tilt: measured in mortise view as the angle between the tibial plafond and the talar joint line. 2d Tibiofibular overlap: defined as the distance between the medial edge of the fibula and incisura fibularis and measured 10 mm proximal to the tibial plafond in mortise view. 2e Oblique medial clear space: measured between the inferior-medial corner of the tibial plafond and the superior-medial corner of the talus in mortise view. 2f Dime sign: fibula is shortened and reported as “positive” dime sign if the “ball” is broken in mortise view. 2g Lag screw surpassing the bone cortex (bicortical): the distance was measured perpendicular to the cortical line. 2h Distal fibular screws: defined as “positive” if any of the 3 distal screws was bicortical in any projection. 2i Proximal fibular screws: the distance was measured perpendicular to the cortical line of the most penetrating screw in any projection. All measurements were reported in mm or positive/negative

Fig. 3

Fracture reduction criteria measured on post-operative WBCT 3 months after ankle surgery. a Medial step-off: measured in the coronal plane on the slide with the highest degree of step-off. 3b Posterior step-off: measured in the sagittal plane on the slide with the highest grade of step-off (only included if more than 20% of the articulating surface was affected). 3c Fibular rotation: the deviation of rotation of the fibula relative to the tibia was measured as the angle of a line between the posterior and anterior tibial tubercles, and a line between the anterior and posterior tubercle of fibula. Measurements of 3c, 3d, and 3e were always performed 10 mm (10 slides) proximal from the beginning of the distal tibial articular surface in coronal plane. 3d Fibular anteroposterior translation: fibular translational deviation anteriorly or posteriorly relative to tibia. The anterior or posterior deviation is being measured with a line (light blue) perpendicular to the midpoint (turquoise line) of the anterior and posterior fibular tubercle (red line). The point where the light blue line crosses the line between the anterior and posterior tibial tubercle (green line) relative to the respective midpoint of this (green) line defines the anterior and posterior translational deviation (dark blue line). 3e Tibiofibular widening: the distance between the medial aspect of the cortex of the fibula and the lateral aspect of the cortex of the tibia. This distance was measured at an angle perpendicular to the midpoint between the anterior and posterior tibial tubercle. 3f Joint space narrowing: defined as the difference in joint space at 3 months minus 12 months. Measured in sagittal plane as the distance between the articular surface of talus and tibia at the central line of tibia