Low rate of substantial loss of reduction immediately after hardware removal following acromioclavicular joint stabilization using a suspensory fixation system

Abstract

Purpose: To evaluate immediate loss of reduction in patients undergoing hardware removal after arthroscopically assisted acromioclavicular (AC) joint stabilization using a high-tensile suture tape suspensory fixation system and to identify risk factors associated with immediate loss of reduction.

Materials and methods: Twenty-two consecutive patients with a mean age of 36.4 ± 12.6 years (19-56), who underwent hardware removal 18.2 ± 15.0 months following arthroscopically assisted stabilization surgery using a suspensory fixation system for AC joint injury between 01/2012 and 01/2021 were enrolled in this retrospective monocentric study. The coracoclavicular distance (CCD) as well as the clavicular dislocation/acromial thickness (D/A) ratio were measured on anterior-posterior radiographs prior to hardware removal and immediately postoperatively by two independent raters. Loss of reduction, defined as 10% increase in the CCD, was deemed substantial if the CCD increased 6 mm compared to preoperatively. Constitutional and surgical characteristics were assessed in a subgroup analysis to detect risk factors associated with loss of reduction.

Results: Postoperatively, the CCD significantly increased from 12.6 ± 3.7 mm (4.8-19.0) to 14.5 ± 3.3 mm (8.7-20.6 mm) (p < 0.001) while the D/A ratio increased from 0.4 ± 0.3 (- 0.4-0.9) to 0.6 ± 0.3 (1.1-0.1) (p = 0.034) compared to preoperatively. In 10 cases (45%), loss of reduction was identified, while a substantial loss of reduction (> 6 mm) was only observed in one patient (4.5%). A shorter time interval between index stabilization surgery and hardware removal significantly corresponded to immediate loss of reduction (11.0 ± 5.6 vs. 30.0 ± 20.8 months; p = 0.007), as hardware removal within one year following index stabilization was significantly associated with immediate loss of reduction (p = 0.027; relative risk 3.4; odds ratio 11.67).

Conclusions: Substantial loss of reduction after hardware removal of a high-tensile suture tape suspensory fixation system was rare, indicating that the postoperative result of AC stabilization is not categorically at risk when performing this procedure. Even though radiological assessment of the patients showed a statistically significant immediate superior clavicular displacement after this rarely required procedure, with an increased incidence in the first year following stabilization, this may not negatively influence the results of ACJ stabilization in a clinically relevant way.

Level of evidence: IV.

Keywords: AC joint stabilization; Acromioclavicular joint injury; Acromioclavicular joint instability; Arthroscopically assisted; Hardware removal; Loss of reduction.

Fig. 1

Measurement protocol. “CO”, tip of the coracoid; “CL”, inferior cortex of the clavicle; distance “CCD”, coracoclavicular distance measured between CO and CL; distance “A”, acromial thickness measured as the distance between the superior and inferior margin of the acromion; line “RL”, reference line at the inferior acromial cortex placed perpendicularly to A; distance “D”, distance between RL and the lowest and most lateral point on the clavicle measured perpendicularly to RL

Fig. 2

Flow chart visualizing the patient population for this study after accounting for inclusion and exclusion criteria. CC coracoclavicular

Fig. 3

Boxplot graph visualizing pre- and postoperative outcomes of the radiological analysis for a coracoclavicular distance (CCD) and b dislocation/acromial thickness (D/A) ratio measurement for the hardware removal procedure. Boxes: median ± Q1 and Q3, whiskers: min. and max value of each data set, *p < 0.05, **p < 0.001, ***p < 0.001