The Role of Pectoralis Minor Tightness in the Development of Rotator Cuff Tears (PMinor-Rotator)

The Role of Pectoralis Minor Muscle Tightness in the Development of Rotator Cuff Tears: A Propensity Score Matched Case-Control Study

This study investigates whether tightness of a small chest muscle called the pectoralis minor is associated with the development of rotator cuff tears in the shoulder. Using a propensity score matched case-control design, the study compares patients with rotator cuff tears (case group, n=45) to patients with intact rotator cuffs (control group, n=45).

Adults aged 18-55 with shoulder pain who are evaluated by MRI and/or shoulder arthroscopy at Gazi University Hospital may be invited. The case group includes patients found to have rotator cuff tears during arthroscopy. The control group includes patients whose rotator cuff was documented as intact by MRI and/or arthroscopy (e.g., patients treated for labral, SLAP, or instability pathology). Groups are matched 1:1 on age, sex, BMI, occupation, sportive activity and dominant side.

Before surgery, a trained clinician measures shoulder posture and pectoralis minor length using simple external tools (a digital caliper and ruler-like square). For arthroscopy patients, the surgeon records general arthroscopic findings. No extra procedures are added for research.

We expect to include 90 participants total. The primary hypothesis is that pectoralis minor tightness is more prevalent in patients with rotator cuff tears compared to controls. A secondary hypothesis is that tears in patients with pectoralis minor tightness more often begin on the bursal side. Results may help clinicians understand shoulder mechanics and improve prevention or rehabilitation strategies.

Study Overview

• Status: Recruiting
• Conditions: Rotator Cuff Injuries; Shoulder Impingement Syndrome; Pectoralis Minor Muscle Tension; Pectoralis Minor Tightness

Detailed Description

Rationale and Objectives Pectoralis minor (PM) tightness alters scapular position (anterior tilt, internal rotation) and may increase subacromial compression. This propensity score matched case-control study evaluates whether PM tightness is associated with the development of rotator cuff tears (RCTs) and, secondarily, whether tears in PM-tight shoulders more often begin on the bursal side.

Design and Setting Single-center, propensity score matched case-control study at a tertiary academic hospital (orthopaedic shoulder service, Gazi University Hospital). Care is not altered by participation. All surgical and imaging procedures are standard of care; research procedures are limited to noninvasive postural/PM length measurements and structured data collection.

Participants Case group (n=45): Patients who underwent shoulder arthroscopy performed by Prof. Dr. Ulunay Kanatli and were found to have rotator cuff tears intraoperatively.

Control group (n=45): Patients presenting with shoulder pain whose rotator cuff was documented as intact by MRI and/or arthroscopy. This includes patients who underwent arthroscopy for labral, SLAP, or instability pathology without rotator cuff tear, and patients with MRI-confirmed intact rotator cuff.

Matching: Propensity score matching (nearest neighbor, caliper 0.2 SD) on age, sex, BMI, and dominant side using R MatchIt package.

Key exclusions: prior ipsilateral shoulder surgery; acute fracture/dislocation; major-trauma RCT; cervical radiculopathy/thoracic outlet syndrome; systemic inflammatory arthropathy; barriers to consent.

Study Procedures

Preoperative assessments (same-day or pre-op clinic):

• Pectoralis minor length (mm): Linear distance from coracoid tip to rib attachment measured with a digital caliper (ICC 0.83-0.87); three trials recorded; mean used for analysis.
• Medial scapular border-thoracic distance (mm) using digital calipers (ICC 0.88-0.97).
• Forward shoulder posture using a 300 mm square (ICC 0.89).
• Imaging abstraction: Standard shoulder radiographs and MRI summarized.

Intraoperative assessment (for arthroscopy patients):

Surgeons document tear initiation site (bursal vs articular) and tear characteristics using a standardized form based on video visualization.

Sample Size and Power Based on a conditional logistic regression framework: OR=3.0, alpha=0.05 (two-sided), power=0.80, with 10% dropout allowance. Total n=90 (45 case + 45 control).

Statistical Analysis Plan

• Software: IBM SPSS Statistics-26, R (MatchIt package)
• Normality: Shapiro-Wilk test
• Comparisons: Paired t-test / Wilcoxon / McNemar for matched pairs
• Multivariable: Conditional logistic regression
• Primary outcome: Presence of rotator cuff tear (case vs control) as a function of PM tightness
• Secondary outcome: Tear initiation site (bursal vs articular) as a function of PM length in the case group
• Significance level: two-sided alpha=0.05

Quality Assurance

• All measurements by a single trained investigator (intra-rater reliability)
• Video recordings retained for intraoperative assessment verification
• Data stored on encrypted drives (KVKK compliant)

• Study Type: Observational
• Enrollment (Estimated): 90

Contacts and Locations

• Study Contact: Name: Cagatay Delice; Phone Number: +90 546 5819056; Email: cgty_166@hotmail.com

Study Locations

• Turkey (Türkiye)
  • Cankaya
    • Ankara, Cankaya, Turkey (Türkiye), 06500
      • Recruiting
      • Gazi University Hospital
      • Contact: Cagatay Delice; Phone Number: +90 546 581 9056; Email: cgty_166@hotmail.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

Adult patients (18-55 years) receiving care at a tertiary orthopaedic shoulder service (Gazi University Hospital, Ankara, Türkiye). Case group: patients who underwent shoulder arthroscopy and were found to have partial- or full-thickness rotator cuff tears. Control group: patients with shoulder pain whose rotator cuff integrity was confirmed intact by MRI and/or arthroscopy. Groups are propensity score matched 1:1 on age, sex, BMI, and dominant side.

Description

Inclusion Criteria:

• Adults 18 to 55 years old.
• Shoulder pain.
• Evaluated by MRI and/or shoulder arthroscopy.
• Willing to take part and give informed consent.

Exclusion Criteria:

• Previous surgery on the same shoulder.
• Recent traumatic shoulder injury such as fracture or dislocation.
• Rotator cuff tear due to major trauma.
• Neck/nerve conditions affecting the shoulder, such as cervical radiculopathy or thoracic outlet syndrome.
• Systemic inflammatory joint disease, such as rheumatoid arthritis or ankylosing spondylitis.
• Cognitive or communication problems that would prevent accurate measurements or consent.

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort
Rotator Cuff Tear (Case); Patients who underwent shoulder arthroscopy and were found to have rotator cuff tears during surgery. Pectoralis minor length, medial scapular distance, and forward shoulder posture were measured preoperatively. Propensity score matched 1:1 with the control group on age, sex, BMI, and dominant side.
Intact Rotator Cuff (Control); Patients presenting with shoulder pain whose rotator cuff was documented as intact by MRI and/or intraoperative arthroscopy findings. Includes patients who underwent arthroscopy for labral, SLAP, or instability pathology without rotator cuff tear, and patients with MRI-confirmed intact rotator cuff. Propensity score matched 1:1 with the case group on age, sex, BMI, and dominant side.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Pectoralis minor muscle length difference between case and control groups	Comparison of pectoralis minor (PM) muscle length (mm) between patients with rotator cuff tears (case group) and patients with intact rotator cuffs (control group). PM length is measured as the linear distance from coracoid tip to rib attachment using a digital caliper. Primary analysis: conditional logistic regression evaluating whether PM tightness is associated with rotator cuff tear presence in propensity score matched pairs.	Preoperative assessment, Day 0

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Forward shoulder posture	Anterior displacement of the acromion relative to the thorax measured with a square ruler (standardized upright position). Three trials; mean used.	Preoperative assessment, Day 0
Medial Scapular Border Thoracic Distance	Periscapular prominence measured with calipers at the medial scapular border in standardized upright posture; three trials, mean used.	Preoperative assessment, Day 0
Thoracic Kyphosis (Cobb angle)	Lateral thoracic radiograph measured using the Cobb method: superior endplate line of T5 and inferior endplate line of T12 (use closest visible end vertebrae if either is obscured). Lines perpendicular to each endplate are drawn; the included angle is recorded as the thoracic kyphosis Cobb angle. One trained assessor performs the measurement; a second assessor repeats it in a 15-case subset for reliability.	Preoperative imaging review, Day 0
Scapular index (Coracoid-Sternum/Acromian lateral tip - thoracic spine)	Ration of two linear distances measured with a digital caliper in standardized upright posture arms relaxed at sides.; Coracoid-Sternum (mm) : shortest straight-line distance from the coracoid tip to the midline of the sternum at the manubrium level.; Acromian lateral tip - Thoracic spine: straight-line distance from the most lateral point of the acromion to the tip of the thoracic spine. Scapular Index = (Coracoid-Sternum) / (Acromion- Thoracic spine). Three trials per shoulder; the mean ratio is used for analysis. A 15-case subset will be re-measured by a second rater to assess inter-rater reliability.	Preoperative assessment, Day 0
Tear initiation site in the case group	Arthroscopic classification of the surface on which the rotator cuff tear appears to begin (bursal vs articular), recorded with a standardized intraoperative checklist in the case group only. Analysis evaluates whether PM-tight patients more frequently exhibit bursal-side tear initiation compared to non-tight patients within the RCT group.	Intraoperative, Day 0 (index arthroscopy)

Collaborators and Investigators

• Sponsor: Gazi University

Publications and helpful links

General Publications

• Yamaguchi K, Ditsios K, Middleton WD, Hildebolt CF, Galatz LM, Teefey SA. The demographic and morphological features of rotator cuff disease. A comparison of asymptomatic and symptomatic shoulders. J Bone Joint Surg Am. 2006 Aug;88(8):1699-704. doi: 10.2106/JBJS.E.00835.
• Borstad JD. Measurement of pectoralis minor muscle length: validation and clinical application. J Orthop Sports Phys Ther. 2008 Apr;38(4):169-74. doi: 10.2519/jospt.2008.2723. Epub 2007 Nov 21.
• Ludewig PM, Reynolds JF. The association of scapular kinematics and glenohumeral joint pathologies. J Orthop Sports Phys Ther. 2009 Feb;39(2):90-104. doi: 10.2519/jospt.2009.2808.
• Cools AM, Struyf F, De Mey K, Maenhout A, Castelein B, Cagnie B. Rehabilitation of scapular dyskinesis: from the office worker to the elite overhead athlete. Br J Sports Med. 2014 Apr;48(8):692-7. doi: 10.1136/bjsports-2013-092148. Epub 2013 May 18.
• Kibler WB, McMullen J. Scapular dyskinesis and its relation to shoulder pain. J Am Acad Orthop Surg. 2003 Mar-Apr;11(2):142-51. doi: 10.5435/00124635-200303000-00008.
• Borstad JD, Ludewig PM. The effect of long versus short pectoralis minor resting length on scapular kinematics in healthy individuals. J Orthop Sports Phys Ther. 2005 Apr;35(4):227-38. doi: 10.2519/jospt.2005.35.4.227.
• Oyama S, Myers JB, Wassinger CA, Daniel Ricci R, Lephart SM. Asymmetric resting scapular posture in healthy overhead athletes. J Athl Train. 2008 Oct-Dec;43(6):565-70. doi: 10.4085/1062-6050-43.6.565.
• Peterson DE, Blankenship KR, Robb JB, Walker MJ, Bryan JM, Stetts DM, Mincey LM, Simmons GE. Investigation of the validity and reliability of four objective techniques for measuring forward shoulder posture. J Orthop Sports Phys Ther. 1997 Jan;25(1):34-42. doi: 10.2519/jospt.1997.25.1.34.
• Du WY, Huang TS, Hsu KC, Lin JJ. Measurement of scapular medial border and inferior angle prominence using a novel scapulometer: A reliability and validity study. Musculoskelet Sci Pract. 2017 Dec;32:120-126. doi: 10.1016/j.msksp.2017.08.004. Epub 2017 Aug 15.

Study record dates

Study Major Dates

• Study Start (Actual): March 18, 2025
• Primary Completion (Estimated): May 25, 2026
• Study Completion (Estimated): May 30, 2026

Study Registration Dates

• First Submitted: November 13, 2025
• First Submitted That Met QC Criteria: November 13, 2025
• First Posted (Actual): November 14, 2025

Study Record Updates

• Last Update Posted (Actual): May 28, 2026
• Last Update Submitted That Met QC Criteria: May 23, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Posture; Arthroscopy; Scapula; rotator cuff; Shoulder Joint; Rotator Cuff Injuries; Pectoralis Minor; Pectoralis Muscles
• Additional Relevant MeSH Terms: Shoulder Injuries; Musculoskeletal Diseases; Wounds and Injuries; Joint Diseases; Rupture; Tendon Injuries; Rotator Cuff Injuries; Shoulder Impingement Syndrome
• Other Study ID Numbers: E-77082166-302.08.01-1273486

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No