The study protocol was approved by the Institutional Review Board of The Affiliated Hospital of Xuzhou Medical University before data extraction and analysis (Approval No. XYFY2026-KL188-01). The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. Given the retrospective nature of the study and the use of routinely collected clinical data, the requirement for participant-informed consent was waived by the Institutional Review Board of The Affiliated Hospital of Xuzhou Medical University. All direct patient identifiers were removed before analysis.
Study design and cohort establishment
This single-center retrospective comparative cohort study included consecutive patients treated between January 2018 and December 2024 for reparable rotator cuff tears accompanied by preoperative shoulder stiffness. Patients who underwent arthroscopic rotator cuff repair with concomitant capsular release were assigned to the capsular release group (CR group), whereas those who underwent repair without capsular release were assigned to the no capsular release group (No CR group). No formal a priori sample-size calculation was performed because this was a retrospective cohort study. All consecutive patients who met the eligibility criteria during the predefined study period were included, and the available cohort therefore determined the final sample size of 124 patients.
Treatment allocation was not randomized and reflected clinical and intraoperative judgment. Active range-of-motion thresholds were used to identify the eligible clinically stiff cohort, but active restriction alone was not considered proof of capsular contracture because pain and rotator cuff-related weakness could also limit active motion. The decision to perform capsular release was based on the combined assessment of preoperative active motion restriction, persistent passive limitation during examination under anesthesia, and arthroscopic evidence of clinically relevant capsular contracture. Examination under anesthesia was used to reduce the influence of voluntary guarding and pain during assessment of passive motion. These findings informed treatment selection but did not constitute a randomized allocation rule. The same operative indications were applied throughout 2018–2024. Measured baseline differences associated with clinical treatment selection were addressed in the statistical analysis, although residual confounding could not be excluded. The screening process, eligibility assessment, exclusions, and final group allocation are presented in Figure 1.
Patient population and eligibility criteria
The source population consisted of adults who underwent arthroscopic treatment for symptomatic rotator cuff tears after unsuccessful nonoperative management, including medication, activity modification, supervised rehabilitation, or local injection. Preoperative physiotherapy was considered an important component of conservative treatment and, when clinically appropriate, included supervised pain-limited range-of-motion exercises and shoulder rehabilitation. Surgery was considered only when clinically meaningful pain, functional limitation, or shoulder stiffness persisted despite these measures. Because treatment was individualized in routine clinical practice, the duration and intensity of preoperative physiotherapy were not completely standardized.
Patients were eligible if they were at least 18 years old; had a symptomatic rotator cuff tear confirmed by magnetic resonance imaging and arthroscopy; had persistent pain or functional limitation despite nonoperative treatment; met the definition of preoperative shoulder stiffness; had a reparable tear treated during the index procedure; completed clinical assessments at baseline and 3, 6, and 12 months after surgery; and underwent structural assessment of the repair by magnetic resonance imaging at approximately 12 months. Preoperative shoulder stiffness was defined by at least one of the following findings in the affected shoulder: active forward elevation below 120°, active external rotation below 30° with the arm at the side, or internal rotation behind the back below the L3 vertebral level. Eligibility was based on preoperative active motion to identify patients with clinically meaningful motion restriction; this operational definition did not by itself establish the presence of capsular contracture. Because active motion could also be limited by pain or cuff-related weakness, persistent passive limitation during examination under anesthesia and arthroscopic evidence of capsular contracture were used to support the operative decision regarding capsular release. Active forward elevation and external rotation were analyzed longitudinally. Internal rotation was retained for stiffness classification but was not analyzed as a repeated continuous variable.
Patients were excluded for an irreparable massive rotator cuff tear, previous surgery on the affected shoulder, advanced glenohumeral osteoarthritis, acute shoulder fracture or dislocation, inflammatory arthropathy, active infection, neurologic disease affecting shoulder motion, or isolated adhesive capsulitis without a reparable rotator cuff tear. Patients with incomplete perioperative records, incomplete follow-up, or unavailable 12-month structural assessment were also excluded.
Preoperative clinical assessment
Baseline variables included age, sex, body mass index, diabetes mellitus, current smoking status, dominant-arm involvement, and symptom duration. Symptom duration was calculated from the documented onset of persistent symptoms to the date of surgery or obtained from the preoperative clinical record when an exact onset date was unavailable. For patients with diabetes mellitus, preoperative glycated hemoglobin (HbA1c) values obtained within 3 months before surgery were extracted when available. However, HbA1c testing was not performed within a uniform preoperative time window for all patients because of the retrospective study design. Diabetes status was therefore included as a prespecified covariate, whereas HbA1c was not entered into the primary multivariable models because of incomplete availability. Patients with diabetes received routine perioperative glucose management according to institutional clinical practice.
Shoulder function was assessed using the American shoulder and elbow surgeons (ASES) score and the Constant score, each ranging from 0 to 100, with higher scores indicating better function. Assessments were completed before surgery and at 3, 6, and 12 months postoperatively. Pain was measured using a 10-point visual analog scale (VAS), with 0 indicating no pain and 10 indicating the worst pain imaginable. VAS scores were recorded at baseline and at each postoperative assessment.
Range-of-motion assessment
Active forward elevation and external rotation were measured at baseline and at 3, 6, and 12 months after surgery using the same institutional examination protocol. Measurements were recorded in degrees. For forward elevation, the patient was positioned standing or seated with the trunk upright and asked to elevate the affected arm actively without assistance. Natural scapular movement was permitted, while compensatory trunk extension and lateral bending were minimized. The maximum active elevation was recorded. For external rotation, the arm was maintained against the trunk with the elbow flexed to 90°. The patient rotated the forearm externally while keeping the upper arm at the side. The angle from the neutral forearm position to maximum active external rotation was recorded.
Internal rotation was assessed by asking the patient to place the hand behind the back and move the thumb superiorly along the spine. The highest vertebral level reached was documented. Measurements were repeated when compensatory movement occurred or the required position was not maintained. Range-of-motion assessors were not consistently blinded to treatment allocation, creating a potential risk of detection bias.
Preoperative imaging and tear characterization
Preoperative magnetic resonance imaging was used to confirm the rotator cuff tear and evaluate tear location, size, morphology, and apparent reparability. Imaging findings were verified arthroscopically. When imaging and operative findings differed, the arthroscopic assessment was used for final classification. Tear size was classified according to the DeOrio and Cofield system as small (<1 cm), medium (1–3 cm), large (>3–5 cm), or massive (>5 cm). Irreparable massive tears were excluded. Tear morphology was classified as crescent-shaped, U-shaped, or L-shaped. Tendon involvement was recorded as isolated supraspinatus involvement, combined supraspinatus and infraspinatus involvement, or partial subscapularis involvement.
Surgical procedures
All operations were performed arthroscopically under general anesthesia, with or without an interscalene regional block, by two fellowship-trained shoulder and elbow surgeons, each with more than 10 years of independent experience in arthroscopic shoulder surgery. After anesthesia induction, passive forward elevation, external rotation, and internal rotation were reassessed to determine whether restriction persisted after minimizing voluntary guarding and pain. Passive restriction under anesthesia was interpreted together with the preoperative examination and arthroscopic capsular findings rather than as an isolated criterion.
Standard posterior viewing and anterior working portals were established. Diagnostic glenohumeral arthroscopy was used to inspect the articular surfaces, labrum, long head of the biceps tendon, rotator interval, capsule, and articular surface of the cuff. The subacromial space was then examined to assess tear configuration, tendon mobility, tissue quality, and footprint characteristics. Rotator cuff repair was performed after tendon mobilization and preparation of the greater tuberosity footprint. A single-row or double-row construct was selected according to tear size, configuration, mobility, and tissue quality. Suture anchors were inserted into the prepared footprint, and sutures were passed through viable tendon tissue to restore tendon-to-bone contact without excessive tension. Repair configuration, anchor number, tear characteristics, and tendon-mobilization procedures were recorded.
In the CR group, capsular release was performed after diagnostic arthroscopy and before final cuff fixation. Release initially involved the rotator interval and anterior capsule. When the restriction remained, the release was extended cautiously toward the inferior capsule. During inferior release, instruments were maintained close to the glenoid rim to reduce the risk of axillary nerve injury. Posterior release was performed only when clinically relevant posterior restriction persisted. Complete circumferential release was not routinely performed, and no separate forceful manipulation under anesthesia was used.
In the No CR group, rotator cuff repair was completed without deliberate rotator interval release or capsulotomy. Standard debridement, subacromial bursectomy, tendon mobilization, and footprint preparation were permitted but were not classified as stiffness-directed capsular release. Biceps tenotomy or tenodesis and acromioplasty were performed when indicated by intraoperative findings. Repair configuration, associated procedures, operative time, and estimated blood loss were recorded.
Postoperative management
The same staged rehabilitation protocol was applied to both groups. The operated shoulder was protected in a sling immediately after surgery, and supervised rehabilitation generally began during the first postoperative week. Early management included pain and edema control, movement of the elbow, wrist, and hand, scapular exercises, and protected passive shoulder motion within surgeon-approved limits.
The sling was maintained for approximately 4–6 weeks according to tear size, repair configuration, tissue quality, and clinical progress. Passive forward elevation and external rotation were advanced gradually without forceful stretching. After sling removal, patients progressed from passive to active-assisted and then active motion, generally between 4 and 8 weeks postoperatively. Resisted strengthening usually began after 12 weeks when active motion and repair stability were considered adequate. Return to unrestricted overhead activity or heavy loading required satisfactory motion, strength, pain control, and surgeon approval. The CR and No CR groups followed the same rehabilitation stages and motion goals. Rehabilitation progression was modified according to pain, tear characteristics, fixation stability, and clinical assessment rather than treatment allocation. Clinical evaluations were performed at approximately 3, 6, and 12 months after surgery. Pain, active range of motion, functional scores, complications, and additional stiffness-related treatments were recorded at each visit. Repair integrity was assessed by magnetic resonance imaging at approximately 12 months.
Outcome assessment
The principal outcomes were postoperative shoulder function and active range-of-motion recovery. The American Shoulder and Elbow Surgeons (ASES) score, Constant score, active forward elevation, and active external rotation were assessed before surgery and at 3, 6, and 12 months postoperatively. Pain intensity was measured using the 10-point visual analog scale at the same time points.
Estimated time to functional range of motion was defined as the postoperative interval required to achieve both active forward elevation of at least 140° and active external rotation of at least 30°. The earliest documented date on which both criteria were met was recorded. When no interval assessment was available, the corresponding scheduled follow-up visit was used. Consequently, this outcome represented an estimated, visit-based recovery interval rather than an exact, continuously observed event time, and actual attainment could have occurred between documented assessments.
Persistent stiffness at 12 months was defined by at least one of the following findings: active forward elevation below 120°, active external rotation below 30°, or internal rotation behind the back below the L3 vertebral level. Secondary stiffness-related interventions were recorded separately as manipulation under anesthesia, therapeutic injection, or another unplanned procedure performed to manage persistent stiffness or delayed recovery after the index operation. A composite outcome of any secondary stiffness-related intervention was also reported. Routine rehabilitation, scheduled follow-up, and analgesic adjustment were not classified as secondary interventions.
Repair integrity was assessed on 12-month magnetic resonance imaging using the Sugaya classification. Types I–III were classified as intact repairs, whereas types IV and V were classified as retears. Magnetic resonance images were reviewed by two musculoskeletal radiologists with 8 and 12 years of post-training experience, respectively, who were blinded to treatment allocation and clinical outcomes. Imaging findings were reassessed when the descriptive report and recorded Sugaya category were inconsistent, and disagreements were resolved by consensus after joint image review. Postoperative complications included infection, neurologic injury, symptomatic hematoma, repair-related reoperation, and other procedure-related adverse events documented during follow-up. Patient satisfaction was assessed at 12 months using a 0–10 scale, with higher scores indicating greater satisfaction.
Data collection and quality control
Study variables were entered into a structured patient-level dataset using predefined field names and coding rules. Recorded variables included demographic characteristics, comorbidities, symptom duration, preoperative assessments, functional and pain scores, range-of-motion measurements, tear characteristics, repair configuration, concomitant procedures, operative time, estimated blood loss, postoperative interventions, complications, satisfaction, and 12-month structural outcomes. The ASES score, Constant score, visual analog scale pain score, active forward elevation, and active external rotation were stored separately for the preoperative, 3-month, 6-month, and 12-month assessments. Treatment group, diabetes mellitus, smoking status, dominant-arm involvement, persistent stiffness, retear, and complications were coded as categorical variables. Manipulation under anesthesia, therapeutic injection, other secondary procedures, and the composite outcome of any secondary stiffness-related intervention were coded separately. Continuous variables were retained in their original units.
Before analysis, the dataset was checked for duplicate records, missing data, implausible values, visit misclassification, and inconsistencies with the source records. Functional scores and pain values outside their allowable ranges were verified against the original assessments. Range-of-motion measurements, tear classifications, operative procedures, secondary interventions, complications, and 12-month magnetic resonance imaging findings were cross-checked against the clinical, operative, and imaging records. Missing values were not replaced with generated observations.
Statistical analysis
Continuous variables were summarized as mean ± standard deviation or median with interquartile range according to their distributions. Categorical variables were summarized as numbers and percentages. The CR and No CR groups were compared using the independent-samples t-test for approximately normally distributed continuous variables and the Mann–Whitney U test for skewed continuous variables. Categorical variables were compared using the chi-square test or Fisher’s exact test, as appropriate. Baseline demographic and clinical characteristics, tear characteristics, repair configuration, concomitant procedures, operative time, and estimated blood loss were compared between groups. The ASES score, Constant score, visual analog scale pain score, active forward elevation, and active external rotation were summarized at baseline and at 3, 6, and 12 months. Unadjusted between-group comparisons were performed at each assessment, and group-specific mean values with standard deviations were used to display recovery trajectories.
Prespecified multivariable models were used to account for measured baseline differences associated with nonrandom treatment allocation. The core adjustment variables were age, sex, symptom duration, diabetes mellitus, tear size, preoperative active forward elevation, and preoperative active external rotation. Preoperative ASES score was additionally included in the models for postoperative ASES outcomes. Covariates were selected a priori on the basis of clinical relevance and their potential association with treatment selection or postoperative recovery rather than by univariable p-value screening. Diabetes mellitus and tear size were included in the prespecified core models. Tear morphology and repair configuration were not added to the primary models because their distributions were similar between groups, repair configuration was identical across groups, and expanded models for outcomes with limited event counts would have increased the risk of overfitting and unstable estimates.
Multiple linear regression was used to analyze the ASES score at 6 and 12 months and the estimated time to functional range of motion. The recorded or visit-assigned recovery interval was analyzed as a continuous outcome; no interval-censoring model was applied. Accordingly, the estimated effect on recovery time should be interpreted as a difference in visit-based documented attainment rather than an exact time-to-event effect. Results were reported as adjusted mean differences with 95% confidence intervals. Binary logistic regression was used for persistent stiffness and retear at 12 months, with results reported as adjusted odds ratios and 95% confidence intervals. Manipulation under anesthesia, therapeutic injection, other secondary procedures, the composite secondary-intervention outcome, complications, and other binary outcomes with limited event counts were compared using unadjusted categorical analyses. The CR group was coded as 0 and the No CR group as 1. Adjusted mean differences, therefore, represented No CR minus CR, and adjusted odds ratios represented the odds in the No CR group relative to the CR group. A negative adjusted difference in ASES score favored the CR group, whereas a positive difference in estimated time to functional range of motion indicated slower recovery in the No CR group.
Exploratory subgroup analyses of the adjusted 6-month ASES difference were performed according to age (<55 versus ≥55 years), sex, diabetes mellitus, tear size (small or medium versus large), and dominant-arm involvement. The subgroup-defining variable was omitted from the corresponding adjusted model. These analyses were interpreted as exploratory. Linear-model assumptions were assessed using residual diagnostics, and collinearity among adjustment variables was examined before model interpretation. A two-sided p-value below 0.05 was considered statistically significant. Effect estimates were reported with 95% confidence intervals. Statistical analyses were performed using SPSS Statistics, version 26.0.