The aim of this study was to evaluate the impact of the acromioclavicular (AC) joint morphology on the outcome after arthroscopically assisted coracoclavicular (CC)-stabilization surgery with suspensory fixation systems and to investigate if an additional open AC joint reduction and AC-cerclage improves the clinical outcome for patients with certain morphologic AC joint subtypes. It was hypothesized, that patients with a non-flat joint configuration are more likely to benefit from an additional open AC-cerclage, as these morphologic subtypes are prone to an entrapment of the articular disc during closed reduction and thus at risk for a secondary dislocation of the clavicle.
Eighty-one patients (95% male) with an acute (<3 weeks) acromioclavicular joint injury (ACJI), who underwent arthroscopically assisted coracoclavicular (CC) stabilization with suspensory fixation systems with or without a concomitant AC-cerclage between 01/2009 and 06/2017 with a minimum of two years of follow-up were enrolled in this monocentric retrospective level III cohort study. AC joint morphology was assessed on preoperative radiographs and categorized depending on the shape of the articular sided surfaces of acromion and clavicle as “flat” and “non-flat” (“oblique” or “curved”) subtypes. Postoperative Single Assessment Numeric Evaluation (SANE), American Shoulder and Elbow Surgeons (ASES), and visual analogue scale (VAS) for pain were collected. A subgroup analysis of clinical outcomes depending on the surgical technique and morphological subtype of the AC joint was performed. A power analysis was performed to determine the capability of the sample size to detect the minimal clinically important difference of 17 points in the ASES score, assuming a standard deviation of 20 points. A sample size of 46 patients would provide 80% power at an alpha-level of 0.05.
Radiological assessment of AC joint morphology showed 24 (30%) cases of flat type, 38 (47%) cases of curved type and 19 (23%) cases of oblique morphology. Postoperatively, no clinically significant differences could be detected in the outcome of patients that underwent CC-stabilization with or without concomitant AC-cerclage for the flat morphologic subtype (VASrest/max, SANE, ASES: p>0,05) or the non-flat subtype (VASrest: p=0,02; VASmax, SANE, ASES: p>0,05). Furthermore, across the entire collective, no clinically significant difference could be found after the treatment of ACJI via CC-stabilization with or without concomitant AC-cerclage (VASrest/max, ASES: p>0,05; SANE p=0,05) at a mean follow-up of 57±14 months.
In arthroscopically assisted AC-stabilization surgery with suspensory fixation systems for acute AC joint injury, the AC joint morphology did not influence the postoperative outcome, independently of the surgical technique. No clinically significant benefit of performing an additional horizontal stabilization could be shown in this collective at mid-term follow-up.