Contact between the coracoacromial arch and the rotator cuff tendons in nonpathologic situations: A cadaveric study

Nobuyuki Yamamoto, Takayuki Muraki, John W. Sperling, Scott P. Steinmann, Eiji Itoi, Robert H. Cofield, Kai Nan An

Research output: Contribution to journalArticle

28 Scopus citations


Hypothesis: A recent ultrasound study has shown that impingement phenomenon was observed in healthy shoulders. We hypothesized that nonpathologic contact beneath the coracoacromial arch occurs in normal shoulders. Materials and methods: Seven fresh-frozen cadaveric shoulders were studied. Each specimen was attached to a custom-designed shoulder-positioning device. A 22-N force was applied to the humeral head to keep it centered in the glenoid fossa. Contact pressure beneath the coracoacromial arch was measured by a flexible force sensor during flexion, abduction, internal and external rotation, extension, and horizontal abduction motions. Bending deformation of the coracoacromial ligament was measured by a linear variable differential transducer sensor. Data were recorded with the arm from 0° to maximum range of motion with 10° increments. Results: Contact pressure with the coracoacromial ligament and acromion was not zero in the neutral position and increased during particular motions, such as flexion, abduction, horizontal abduction, and extension, whereas it was almost constant during internal and external rotation. Bending deformation of the coracoacromial ligament during flexion, abduction, and horizontal abduction motions was also shown to be greater than that during internal and external rotation. Discussion: It is possible that repetitive contact of the coracoacromial ligament may cause degenerative changes, and a ridge of proliferative acromial spurs may be the result of nonpathologic contact. Conclusions: Contact phenomenon of the coracoacromial arch was observed during all motions. Nonpathologic contact beneath the coracoacromial arch may be present in normal shoulders.

Original languageEnglish (US)
Pages (from-to)681-687
Number of pages7
JournalJournal of Shoulder and Elbow Surgery
Issue number5
StatePublished - Jul 2010



  • bending deformation
  • contact pressure
  • nonpathologic contact
  • Subacromial impingement

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Surgery

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