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Multiquadrant digital analysis of shoulder capsular thickness
W J Ciccone1, T J Hunt, R Lieber
1San Diego Sports Medicine and Orthopaedic Center, and the Department of Orthopaedics, the University of California San Diego, USA.
Summary
Shoulder capsule thickness varies significantly, ranging from 1.32 to 4.47 mm, thinning from the glenoid to the humerus. These measurements aid in safely applying thermal energy during shoulder procedures to prevent injury.
Area of Science:
- Orthopedic Surgery
- Biomechanical Engineering
- Anatomy
Background:
- Recurrent shoulder instability can follow arthroscopic stabilization due to plastic capsule deformation.
- Nonablative thermal capsular shrinkage aims to address this by tightening the capsule.
- Optimal thermal shrinkage temperature is known, but safe penetration depth in the shoulder capsule is undefined.
Purpose of the Study:
- To measure shoulder capsule thickness circumferentially and by quadrant.
- To determine thickness variations from the glenoid to the humerus.
- To inform precise application of thermal energy in shoulder procedures and prevent pericapsular injury.
Main Methods:
- Anatomic study using 8 fresh cadaveric shoulder specimens.
- Glenohumeral joint capsules were dissected, frozen, sectioned, and stained.
- Capsule thickness was measured using microscopy and computer imaging software.
Main Results:
- Total capsular thickness ranged from 1.32 mm to 4.47 mm.
- Capsule thickness averaged 3.03 mm at the glenoid and thinned to 2.17 mm at the humeral insertion.
- Significant thickness variation was noted along the specimen length (P < .05).
Conclusions:
- Shoulder capsule thickness varies significantly, thinning laterally from the glenoid to the humerus.
- Thickness near the axillary nerve ranges from 2.76 to 3.18 mm.
- Data provide guidelines for safe thermal penetration depth in capsular shrinkage procedures to avoid injury to surrounding structures.