Study design
This study is a prospective, single-center, parallel-design randomized controlled trial. This protocol has been developed according to the SPIRIT statement [27]. The trial has been prospectively registered in the Chinese Clinical Trial Registry (ChiCTR2000032343). The outline of the study was given in Fig. 1.
Recruitment and informed consent
This study will be conducted in Sun Yat-sen Memorial Hospital. Patients with rotator cuff tears (RCTs) who need arthroscopic rotator cuff repair (RCR) will be recruited from the outpatient center of Sun Yat-sen Memorial Hospital. After accomplishing baseline assessment and confirming the eligibility of the patients, the researcher will introduce the study purposes, procedures, possible risks etc. for approximately 45 min, and answer all the questions raised by patients and their families. Informed consent forms will be signed by each patient. After enrollment, participants will be coded with a unique number.
Eligibility and exclusion criteria
The inclusion criteria are as follows: diagnosis of unilateral degenerative RCTs; pre-operative critical shoulder angle (CSA) ≥33°; required to receive arthroscopic RCR; willing to take part in this study; pre-operative three-dimensional computed tomography (3D-CT) and post-operative standard radiographs of shoulder were performed in our institution. The exclusion criteria are: history of shoulder trauma, and concomitant fracture or dislocation of shoulder; previous surgery of the involved shoulder; diagnosis of massive rotator cuff tears; concomitant frozen shoulder, glenohumeral osteoarthrtitis (OA) or other inflammatory arthritis; unable to give informed consent.
Randomization
After informed consent, eligible participants will receive a unique number. Then, patients will be randomly allocated to either the anterolateral acromioplasty group (Group A), the lateral acromioplasty group (Group B), or precise acromioplasty group (Group C) via a random, computer-generated number system. The treating surgeon will determine surgical plans according to the results of the randomization allocation. Allocation will be based on a 1:1:1 ratio between the three different groups.
Blinding
In this study, participants will be clearly informed of surgical plans before operation. Besides, the surgeon and assistant will perform acromioplasty along with arthroscopic RCR. Consequently, the patients, treating surgeon and assistant are not blinded to the group allocation. However, the surgeon and assistant will not participate in the pre-operative and post-operative assessment, and other researchers will blinded to the surgical decision making.
Interventions
All patients will receive a routine examination during admission, including routine blood and urine tests, as well as evaluation of general condition. Imaging examination, such as a 3D-CT of shoulder and MRI (if necessary), will be completed before enrollment. All participants will complete standard anteroposterior radiography of shoulders 2 days post-operation and follow-up will be continued at 3, 6 and 12 months after surgery. This trial will involve three types of acromioplasty: anterolateral, lateral or precise acromioplasty. One of these acromioplasties will be randomly performed along with arthroscopic RCR in each group.
Surgical procedures
One professional surgeon will make the surgical plan and conduct the arthroscopy in Sun Yat-sen Memorial Hospital. All participants will undergo general anaesthesia and be fixed in lateral decubitus. The surgery will begin with the establishment of a standard posterior portal and diagnostic arthroscopy. Then the arthroscopic RCR will be performed depending on the tear location and size. Later, three different acromioplasties will be conducted in groups A, B and C respectively according to a random allocation as previously described. The main processes of the acromioplasties are described below.
In group A, after the undersurface of the acromioclavicular joint and the anterolateral margin of the acromion are freed from all soft tissue via a 5 mm shaver burr (Arthrex Inc., Naples, USA), the surgeon will gradually resect the anterolateral acromion from the anterolateral corner, perpendicular to the line from the anterior third lateral edge of the acromion to anterior acromioclavicular joint line margin. The anterolateral acromioplasty in group A will involve a width of approximately 10 mm (two shaver burr widths).
In group B, after the undersurface and lateral margin of the acromion are freed from all soft tissue, the lateral acromioplasty will be started inferiorly at the middle lateral edge of the acromion, perpendicular to the line from the anterolateral to the posterolateral corner of the acromion. The lateral acromioplasty in group B will involve a width of approximately 10 mm (two shaver burr widths).
In group C, the pre-operative CSA (≥33°) will be measured on the 3D model. We will set 30° for the CSA as the post-operative target degree. Second, the virtual acromioplasty will be simulated and the resected bone border will be measured upon the Mimics (Materialise, Leuven, Belgium), including the anterolateral corner of acromion (A), anteromedial resection margin (B), posterolateral resection margin (C), and the distance of AB and AC. Third, the surgeon will identify and mark points A, B and C on the patient’s skin by measurement the distance of AB and AC according to the pre-operative planning above. Then, after the undersurface of the acromion are freed from all soft tissue, the surgeon will insert points A, B and C with spinal needles perpendicularly from the skin to the subacromial space as line marks, a resection line will be made from B to C during arthroscopy. Lastly, the region of the acromion outside the resection line will be gradually resected by a 5 mm shaver burr (Arthrex Inc., Naples, FL, USA) during arthroscopy. The main procedure is shown schematically in Fig. 2.
Outcome measures
General information and baseline assessment will be collected during admission. The post-operative CSA will be measured 2 days post-operation. Follow-up will be maintained at 3, 6, and 12 months after surgery, including the visual analog scale (VAS) score, the University of California at Los Angeles (UCLA) score, the Constant Shoulder Score (CSS) and the American Shoulder and Elbow Surgeon (ASES) Shoulder Assessment Form. All outcomes will be assessed by two researchers who are blinded to the recruitment and allocation.
Primary outcome
Pre-operative CSA on 3D scapula
The pre-operative CSA of patients will be measured on 3D-CT model before enrollment. First, Digital Imaging and Communications in Medicine (DICOM) data from CT scans of the shoulders will be used to reconstruct 3D scapulae by Mimics (Materialise, Leuven, Belgium). Then, the 3D model will be imported into Blender (Amsterdam, Netherlands) and aligned to the local coordinate system according to the same criteria as described by Suter et al. [28]. Lastly, the CSA, which is measured as the angle between a line connecting the inferior border of the glenoid with the most inferolateral point of the acromion and another connecting inferior and superior glenoid margin [12], will be measured on anterior view using Blender (Fig. 3a). Patients with a native CSA ≥33° will be recruited as candidates.
Post-operative CSA on X-ray
The post-operative CSA of participants will be measured on standard anteroposterior radiography of the shoulder (Fig. 3b). The efficacy is reflected in the reduction of CSA after acromioplasty. The accuracy is defined as the percentage of patients whose post-operative CSA decreased from a large angle (≥33°) to a normal range (30–33°) via acromioplasty.
Secondary outcome
Shoulder function scores
Subjective pain will be ranked by the patients on the visual analog scale (VAS) score for pain, with 0 indicating no pain at all and 10 indicating the most severe pain the patient could imagine. The University of California at Los Angeles (UCLA) score, the Constant Shoulder Score (CSS) and the American Shoulder and Elbow Surgeon (ASES) Shoulder Assessment Form will be used for the functional assessment.
Adverse event management
In this study, the different interventions for participants who are willing to receive arthroscopic RCR are three diverse acromioplasties, which are relatively safe procedures during minimally invasive surgery. Adverse events are defined as any unexpected medical incidents which happen in participants and do not necessarily have a causality with the acromioplasty, including acromial fractures, detachment of deltoid origin, and either pain or swelling due to bone removal of acromion. Participants will report any adverse events to doctors or study researchers as soon as they can. All adverse events will be documented and further medical treatment will be arranged if necessary. In addition, the participants will be closely followed up until conditions are resolved or their condition is stabilized.
Data management
Participants will be coded with a study number after informed consent, and all data referring to patients will be documented by this number, not by name. A case report form (CRF) will be used for participants to collect information including baseline information, radiographic outcomes, and follow-up. Data will be collected at baseline admission and 2 days post-operation, as well as 3, 6 and 12 months post-surgery. Data on adverse events and further medical treatments will also be collected. The recording of data is assigned to a data manager who is accountable for it, and other researchers will be restricted from accessing study data.
Sample size calculation
The primary outcome of this trial is the CSA and a power analysis was performed using PASS 15 (NCSS LLC, USA) to calculate the sample size. According to the results of Kaiser’s study [26] and our preliminary study, the reduction of CSA was 2.6° ± 1.8° (mean ± standard deviation, SD) in group A, 4.4° ± 1.5° in group B, and 4.8° ± 1.6° in group C respectively. Based on a power of 90%, and an alpha error of 0.05, a sample size of 48 patients was determined. After taking into consideration a dropout rate of 20%, a sample of 60 participants (20 participants per group) will be recruited.
Statistical analysis
The analysis of covariance will be conducted to compare the alteration of the CSA and shoulder function scores between randomized groups. The accuracy rates of different acromioplasties will be calculated, and χ2 test will be performed to evaluate the statistical differences between groups. The Spearman correlation coefficients will be used to assess the relationship between CSA and shoulder function scores. The intraclass correlation coefficient will be calculated to assess the consistency between researchers and between measurements of a single researcher. Statistical significance will be set at P < 0.05. All analyses will be carried out using SPSS 19 (IBM Corp, USA) by two researchers blinded to the recruitment and collection.