title: Prevalence of remaining horizontal instability in high-grade acromioclavicular joint injuries surgically managed.
abstract: OBJECTIVE
  To determine the prevalence of remaining horizontal instability in high-grade acromioclavicular joint (ACJ) injuries surgically managed by means of four different surgical strategies and to assess its relation to the clinical outcomes and the quality of life.
  
  
  METHODS
  In this multicentric non-randomized retrospective study, 53 patients with high-grade ACJ injuries surgically managed (by means of open or arthroscopic surgery) were clinically and radiographically assessed at 24 months or more after shoulder surgery. The presence of post-surgical remaining horizontal instability was evaluated by means of Alexander or axillary X-ray views. The study population was divided into two groups: patients with evidence of post-surgical remaining horizontal instability and patients without evidence of post-surgical remaining horizontal instability at the last follow-up visit. The relationship between remaining horizontal instability and the quality-of-life questionnaires was analyzed.
  
  
  RESULTS
  18.87% (10/53) of the Alexander or axillary X-rays views showed post-surgical remaining horizontal instability at the last follow-up visit (INSTAB-group). Results of the questionnaires were: (1) physical SF36 score (INSTAB-group 57.02 ± 3.17  and NO-INSTAB-group 57.66 ± 3.30, p = 0.583); (2) mental SF36 score (INSTAB-group 53.95 ± 3.98  and NO-INSTAB-group 55.71 ± 3.30, p = 0.150); (3) NRS for pain (INSTAB-group 1.30 ± 1.49 and NO-INSTAB-group 0.83  ± 1.08, p = 0.260); (4) DASH questionnaire (INSTAB-group 5.27 ± 5.42 and NO-INSTAB-group 3.06 ± 2.30, p = 0.049); (5) Constant score (INSTAB-group 93.4 ± 3.5 and NO-INSTAB-group 94.83  ± 4.3, p = 0.333); and Global satisfaction (INSTAB-group 8.7  ± 0.95 and NO-INSTAB-group 8.64 ± 1.03, p = 0.874).
  
  
  CONCLUSIONS
  Independently of the type of procedure, post-surgical remaining horizontal instability was present in almost one-fifth of the patients, and this group of patients showed a significantly worse DASH score. The addition of an acromioclavicular augmentation might have to be considered, taking into account that its absence may have a negative impact in terms of shoulder disabilities.
  
  
  METHODS
  Level IV, prognostic case series.
authors.affiliation: Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Sant Quintí 89, 08026, Barcelona, Spain. luisgerardonaterac@gmail.com.|Hospital General de Catalunya, Pedro i Pons 1, 08190, Sant Cugat del Vallés, Barcelona, Spain. luisgerardonaterac@gmail.com.
authors.forename: Luis Natera
authors.initials: LN
authors.lastname: Cisneros
authors.affiliation: Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Sant Quintí 89, 08026, Barcelona, Spain.|Hospital Quirón Teknon, Vilana 12, 08022, Barcelona, Spain.
authors.forename: Juan Sarasquete
authors.initials: JS
authors.lastname: Reiriz
mesh_terms: D000173:Acromioclavicular Joint / Q000000981:diagnostic imaging / Q000293:injuries* / Q000503:physiopathology / Q000601:surgery*; D000328:Adult; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000000981:diagnostic imaging* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D059352:Musculoskeletal Pain / Q000209:etiology; D019637:Orthopedic Procedures / Q000379:methods; D011184:Postoperative Period; D011788:Quality of Life; D011859:Radiography; D012189:Retrospective Studies; D000070599:Shoulder Injuries / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D011795:Surveys and Questionnaires; D055815:Young Adult
keywords: Acromioclavicular augmentation; Alexander X-ray; Axillary X-ray; High-grade ACJ injuries; Horizontal instability; Shoulder disabilities