A large CSA (>35º) is not associated with post-operative functional outcomes in patients with rotator cuff arthroscopic repair but a higher number of retears needing revision surgery was present in the large CSA group.
Recent scientific literature has suggested an association between scapular bony morphometry and the incidence of rotator cuff tears. Recently, the critical shoulder angle (CSA) was proposed as a potential risk factor for degenerative rotator cuff disease. Biomechanical studies support that a large CSA results in greater supraspinatus loading and potentially overload the rotator cuff during repetitive active shoulder abduction. Moreover, CSA has also been proposed as a factor that predisposes the patient to an increased likelihood of retear after surgical repair of a rotator cuff tear. Nonetheless, the influence of a larger CSA on the post-operative functional outcomes after arthroscopic rotator cuff repair is still not well stablished. Thus, the purpose of this study was to examine either a larger CSA is associated to the post-operative functional outcomes after arthroscopic rotator cuff repair. The hypothesis was that a larger CSA (>35º) would result in poorer postoperative outcomes.
A retrospective review of patients that underwent degenerative full-thickness rotator cuff tear arthroscopic repair was conducted. A total of 113 consecutive patients, with a minimum of one year of follow-up and operated between 2013 and 2017, were identified. Eighteen were excluded due to inappropriate pre-operative shoulder radiography and 12 were not available for follow-up. An independent reviewer measured the acromial index (AI), greater tuberosity angle (GTA), lateral acromion angle (LAA) and the CSA from the pre-operative radiographs. Number of retears, Quick Disability of the Arm, Shoulder and Hand (QuickDASH) and the American Shoulder and Elbow Surgeons (ASES) were collected prospectively at a mean follow-up of 37 ± 19 months. Patients were divided into two groups: CSA>35 (large CSA group) and CSA = 35 (control group). Statistical analysis was carried out with SPSS 25.0 software. The Mann-Whitney U test was used to compare the radiographic measures and fuctional scores between the two groups.
A total of 65 patients (61.8 ± 6.6 years old, 82% female; 28.8 ± 3.9 kg/cm2, 40% left shoulder; 5% smokers and 20% had diabetes) were included in the large CSA group and 37 patients (61.6 ± 8.9 years old, 76% female; 28.1 ± 5.1 kg/cm2, 27% left shoulder; 11% smokers and 16% had diabetes) were included in the control group (2.70%). The large CSA groups had 4 (6.15%) retears compared with one on the control groups. Large CSA group had significantly higher CSA (39.8º ± 3.4º versus 32.5º ± 1.7º, p<0.001), lower LAA (73.1º ± 6.6º versus 80.9º ± 5.9º, p<0.001) and higher AI (0.82 ± 0.07 versus 0.75 ± 0.06, p<0.001). GTA showed no significantly differences between groups (65.1º ± 5.4º versus 58.3º ± 5.6º, p=0.07). QuickDASH and ASES functional scores did not show any significant difference between the large CSA and control groups (42.8 ± 21.3 versus 48.1 ± 18.6, p=0.113; 56.1 ± 25.5 versus 53.1 ± 24.0, p=0.587).
A large CSA (>35º) did not influence the post-operative functional outcomes in patients with rotator cuff arthroscopic repair. However a higher number of retears needing revision surgery was present in the large CSA group.