Radiographic appearance of the distal clavicle in relation to the acromion after acromioclavicular joint reconstruction using a braided polyester mesh

Abstract

ACJ stabilization using a braided polyester mesh has become popular in ACJ injuries. However, concerns have been raised about excessive anterior clavicle displacement. The purpose of this study was to report radiographic position of the distal clavicle in relation to the acromion after ACJ reconstruction using this device immediately postoperative and after 6 months follow-up compared with a healthy control group. Thirty-eight patients with ACJ instability treated with a braided polyester mesh were compared within group (pre-/postoperatively) and between groups (with age/sex matched controls). Biplane radiographic measurements by 2 observers were made preoperatively, immediate postoperatively and at 6 months follow-up. Inter-observer reliability was assessed and clinical outcome scores were recorded. ACJ stabilization significantly reduced vertical displacement immediately postoperatively (13.8 ± 4.2 to 3.5 ± 5.5 mm; p < 0.0001) towards controls (1.7 ± 2.3 mm,p < 0.0873). Slight further superior displacement (4.4 mm) occurred at 6 months follow-up compared to immediately postoperative (p = 0.0029) and 6.2 mm more than mean controls (p < 0.0001). In the axial plane, significant early reduction of posterior displacement was achieved (10.3 ± 8.0 to 1.1 ± 5.1 mm,p = 0.0240) and the clavicle settled back to a more posterior position at 4.5 ± 6.7 mm at 6 months post-surgery (p = 0.3062). At both time points, posterior displacement was comparable with the controls (3.4 ± 3.0 mm,p = 0.4371 postoperative, p = 0.563 at 6 months follow-up). Excessive anterior displacement has been observed in 2 of the 5 available axial radiographs early postoperative and in 4 of 14 available axial radiographs at 6 months. Constant, Oxford Shoulder and Nottingham Clavicle scores significantly improved (25 ± 12 to 43 ± 7:p < 0.0001, 46 ± 27 to 80 ± 19:p = 0.0038, 53 ± 14 to 80 ± 17:p < 0.0001). ACJ stabilization using a braided polyester device in ACJ instability is effective at reducing both superior and posterior clavicle displacement with excellent clinical outcome. Overcorrection in the axial plane seems to occur, however this is of no clinical and radiographic significance. Posterior displacement is significantly reduced towards control values at 6 months follow-up.

Fig. 1

a. (left-hand side) The superior-inferior displacement recorded was measured on the AP view - undersurface of lateral end clavicle to undersurface medial acromion (Superior defined as positive). b. (right-hand side) The anterior-posterior displacement was measured on the axial view - anterior surface lateral end of clavicle to most anterior prominence of acromion (Posterior defined as positive).

Fig. 2

Nottingham clavicle score.

Fig. 3

ACJ stabilization using a braided polyester mesh around the corocoid process and clavicle fixed with a screw from anterior to posterior through the clavicle.

Fig. 4

Bland Altman plots comparing the two observers for the AP and axial data.