Biomechanical similarities among subscapularis repairs after shoulder arthroplasty.
OBJECTIVE
Many authors suggest that subscapularis deficiency after shoulder arthroplasty has a negative effect on long-term outcomes. Thus, increasing emphasis has been placed on the technique for repair of the tendon. This study evaluated the biomechanical strength of 3 different repairs: osteotomy, tendon to bone, and a combined method.


METHODS
Twenty-four paired shoulders from deceased donors were prepared for shoulder arthroplasty. The subscapularis tendon was removed/repaired with the lesser tuberosity in the osteotomy group, was removed periosteally in the bone-to-tendon group, and was tenotomized in the combined group. The tendon-to-bone repair used bone tunnels, and the combined construct added tendon-to-tendon fixation. A materials testing system machine was used for cycling. A digital motion analysis system with spatial markers was used for analysis.


RESULTS
There were no significant differences (P > .05) in age, bone mineral density, or construct thickness. No statistically significant differences (P > .05) in elongation amplitude (P = .67) or cyclic elongation (P = .58) were detected within the constructs or between repair techniques. Failure testing revealed no differences in maximum load, stiffness, or mode of failure.


CONCLUSIONS
There remains no consensus about the optimal method of repairing the subscapularis tendon during shoulder arthroplasty. Furthermore, the results of the current study do not support one technique over another with regard to initial fixation properties. All constructs investigated exhibited comparably robust biomechanical performance. Durability may, therefore, be more a result of healing potential than the specific construct chosen.
Van Thiel
Geoffrey S
GS
Rush University Medical Center, Department of Orthopedic Surgery, Division of Sports Medicine, Chicago, IL, USA.
Wang
Vincent M
VM
Wang
Fan-Chia
FC
Nho
Shane J
SJ
Piasecki
Dana P
DP
Bach
Bernard R
BR
Romeo
Anthony A
AA
D001178:Arthroplasty; D001696:Biomechanical Phenomena; D002102:Cadaver; D006801:Humans; D008297:Male; D008875:Middle Aged; D010027:Osteotomy / Q000379:methods*; D012785:Shoulder Joint / Q000601:surgery*; D013710:Tendons / Q000601:surgery*