The Journal of Bone and Joint Surgery (American). 2005;87:1312-1322.
doi:10.2106/JBJS.C.01031
© 2005 The Journal of Bone and Joint Surgery, Inc.
Comparison of Glenohumeral Mechanics Following a Capsular Shift and Anterior Tightening
Vincent M. Wang, PhD1,
Matthew T. Sugalski, MD2,
William N. Levine, MD2,
Robert J. Pawluk, MS2,
Van C. Mow, PhD3 and
Louis U. Bigliani, MD2
1 Leni and Peter W. May Department of Orthopaedics, Mount Sinai School of
Medicine, One Gustave Levy Place, Box 1188, New York, NY 10029-6574
2 Department of Orthopaedic Surgery, Columbia-Presbyterian Medical Center, 622
West 168th Street, PH11-Center, New York, NY 10032. E-mail address for L.U.
Bigliani:
lub1{at}columbia.edu
3 Department of Biomedical Engineering, Columbia University, 351C Engineering
Terrace, 1210 Amsterdam Avenue, MC 8904, New York, NY 10027
Investigation performed at Columbia University, New York, NY
Background: Numerous surgical techniques have been developed to
treat glenohumeral instability. Anterior tightening procedures have been
associated with secondary glenohumeral osteoarthritis, unlike the
anterior-inferior capsular shift procedure, which has been widely advocated as
a more anatomical repair. The objective of the present study was to quantify
glenohumeral joint translations, articular contact, and resultant forces in
cadaveric specimens in order to compare the effects of unidirectional anterior
tightening with those of the anterior-inferior capsular shift.
Methods: Six normal fresh-frozen cadaveric shoulders were tested on
a custom rig with use of a coordinate-measuring machine to obtain kinematic
measurements and a six-axis load transducer to measure resultant external
joint forces. Shoulders were tested in the scapular plane in three
configurations (normal anatomical, anterior tightening, and anterior-inferior
capsular shift) and in three humeral rotations (neutral, internal, and
external). Glenohumeral articular surface geometry was quantified with use of
stereophotogrammetry for kinematic and contact analyses. Resultant joint
forces were computed on the basis of digitized coordinates of tendon
insertions and origins.
Results: Compared with the controls (maximum elevation, 167°
± 8°), the anteriorly tightened specimens demonstrated loss of
external rotation, significantly restricted maximum elevation (135°
± 16°, p = 0.002), posterior-inferior humeral head subluxation, and
significantly greater posteriorly directed resultant forces at higher
elevations (p < 0.05). In contrast, compared with the controls, the
specimens that had been treated with the anterior-inferior capsular shift
demonstrated a similar maximum elevation (159° ± 11°, p = 0.8)
without any apparent loss of external rotation and with reduced humeral
translation.
Conclusions: Anterior tightening adversely affects joint mechanics
by decreasing joint stability, limiting both external rotation and arm
elevation, and requiring greater posterior joint forces to attain maximum
elevation. The anterior-inferior capsular shift improves joint stability while
preserving external rotation with no significant loss of maximum
elevation.
Clinical Relevance: The results of this in vitro cadaveric study
support clinical observations that the anterior-inferior capsular shift
procedure more closely recreates normal joint mechanics in comparison with
unidirectional anterior tightening procedures.

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