The Journal of Bone and Joint Surgery (American). 2007;89:2477-2484.
doi:10.2106/JBJS.F.00811
© 2007 The Journal of Bone and Joint Surgery, Inc.
Pectoralis Major Tendon Transfers Above or Underneath the Conjoint Tendon in Subscapularis-Deficient ShouldersAn in Vitro Biomechanical Analysis
Gerhard G. Konrad, MD1,
Norbert P. Sudkamp, MD1,
Peter C. Kreuz, MD1,
John T. Jolly, MS2,
Patrick J. McMahon, MD2 and
Richard E. Debski, PhD2
1 Department of Orthopaedic and Trauma Surgery, University of Freiburg,
Hugstetter Strasse 55, 79106 Freiburg, Germany
2 Musculoskeletal Research Center, Departments of Orthopaedic Surgery and
Bioengineering, University of Pittsburgh, 405 Center for Bioengineering, 300
Technology Drive, Pittsburgh, PA 15219. E-mail address for R.E. Debski:
genesis1{at}pitt.edu
Investigation performed at the University of Pittsburgh, Pittsburgh,
Pennsylvania
Disclosure: The authors did not receive any outside funding or
grants in support of their research for or preparation of this work. Neither
they nor a member of their immediate families received payments or other
benefits or a commitment or agreement to provide such benefits from a
commercial entity. No commercial entity paid or directed, or agreed to pay or
direct, any benefits to any research fund, foundation, division, center,
clinical practice, or other charitable or nonprofit organization with which
the authors, or a member of their immediate families, are affiliated or
associated.
Background: Different operative techniques for transfer of the
pectoralis major tendon have been proposed for the treatment of irreparable
ruptures of the subscapularis tendon. The objective of this study was to
compare the effects of two techniques of transferring the pectoralis major
tendon (above or underneath the conjoint tendon) on glenohumeral kinematics
during active abduction in a biomechanical model of a subscapularis-deficient
shoulder.
Methods: Six shoulder specimens were tested with a custom dynamic
shoulder testing apparatus. After the kinematics of the intact shoulder were
recorded, a complete tear of the subscapularis tendon was simulated
surgically. A transfer of the clavicular portion of the pectoralis major
muscle to the lesser tuberosity was then performed with the transferred tendon
placed either above (tendon-transfer 1) or underneath (tendon-transfer 2) the
conjoint tendon. For each condition, the maximum abduction angle as well as
the external rotation angle and the superoinferior and anteroposterior humeral
translations at the maximum abduction angle were recorded.
Results: With the rotator cuff intact, the mean maximum glenohumeral
abduction angle (and standard error of the mean) was 86.3° ±
2.1° and the mean amount of external rotation at the maximum abduction
angle was 5.5° ± 7.6°. A complete tear of the subscapularis
tendon decreased the mean maximum abduction angle to 40.8° ±
2.4° (p < 0.001) and increased the mean external rotation to 91.8°
± 4.8° (p < 0.001). The mean humeral translations in the
anterior and superior directions (+3.4 ± 0.5 and +6.3 ± 0.3 mm,
respectively) at the maximum abduction angle were also increased (p < 0.01
and p < 0.001) when compared with those in the intact shoulder. Significant
differences were found in the mean maximum abduction angle as well as the mean
external rotation angle and humeral translations (anterior and superior) at
maximum abduction between the tendon-transfer-1 condition (63.2° ±
13.5°, 82.4° ± 6.6°, 4.0 ± 1.8 mm, and 3.3 ±
1.9 mm, respectively) and tendon-transfer-2 condition (89.5° ±
12.3°, 45.7° ± 22.5°, –0.6 ± 2.0 mm, and 0.5
± 2.3 mm, respectively). The tendon-transfer-2 condition restored
glenohumeral kinematics that were closer to those in the intact shoulder than
were those resulting from the tendon-transfer-1 condition.
Conclusions: Transfer of the pectoralis major tendon in
subscapularis-deficient shoulders partially restored the glenohumeral
kinematics of the intact shoulder. One possible explanation for the superior
effect of the tendon-transfer-2 condition is that, with a pectoralis major
tendon transfer underneath the conjoint tendon, the line of action of the
transferred tendon is closer to that of the subscapularis muscle.
Clinical Relevance: From a biomechanical standpoint, it may be
preferable to perform a pectoralis major tendon transfer underneath the
conjoint tendon in subscapularis-deficient shoulders.

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