Impact of Arthroscopic Lateral Acromioplasty on the Mechanical and Structural Integrity of the Lateral Deltoid Origin: A Cadaveric Study.
OBJECTIVE
To determine whether a 5-mm and/or 10-mm arthroscopic lateral acromioplasty (ALA) would weaken the structural and mechanical integrity of the lateral deltoid.


METHODS
The acromion and lateral deltoid origin were harvested from 15 pairs (n = 30) of fresh-frozen human cadaveric shoulder specimens. One side of each specimen pair (left or right) was randomly assigned to either a 5-mm (n = 7) or 10-mm (n = 8) ALA group, and the contralateral sides (n = 15) were used as matched controls. Acromion thickness and width were measured pre- and postoperatively. After ALA, specimens were inspected for damage to the lateral deltoid origin. Each specimen was secured within a dynamic testing machine, and the deltoid muscle was pulled to failure. Statistical analysis was performed to determine whether ALA reduced the lateral deltoid's failure load.


RESULTS
There was no significant difference in failure load between the 5-mm ALA group (661 ± 207 N) and its matched control group (744 ± 212 N; mean difference = 83 N; 95% confidence interval [CI], -91 to 258; P = .285) nor between the 10-mm ALA group (544 ± 210 N) and its matched control group (598 ± 157 N; mean difference = 54 N; 95% CI, -141 to 250; P = .532). There was no correlation found between the amount of bone resected (measured by percent thickness and width of the acromion after ALA) and the failure load of the deltoid. Visual evaluation of the acromion after ALA revealed the lateral deltoid origin had no damage in any case.


CONCLUSIONS
ALA did not weaken the structural or mechanical integrity of the lateral deltoid origin. Neither a 5-mm nor a 10-mm ALA significantly reduced the deltoid's failure load. The lateral deltoid origin was not macroscopically damaged in any case.


CONCLUSIONS
ALA can be performed without the potential risk of macroscopically damaging the lateral deltoid origin or reducing its failure load.
Steadman Philippon Research Institute, Vail, Colorado, U.S.A.
Daniel Cole
DC
Marchetti
Steadman Philippon Research Institute, Vail, Colorado, U.S.A.; Department of Trauma, Hand and Reconstructive Surgery, University Hospital Münster, Münster, Germany.
J Christoph
JC
Katthagen
Steadman Philippon Research Institute, Vail, Colorado, U.S.A.
Jacob D
JD
Mikula
Steadman Philippon Research Institute, Vail, Colorado, U.S.A.; Steadman Clinic, Vail, Colorado, U.S.A.
Scott R
SR
Montgomery
Steadman Philippon Research Institute, Vail, Colorado, U.S.A.
Dimitri S
DS
Tahal
Steadman Philippon Research Institute, Vail, Colorado, U.S.A.
Kimi D
KD
Dahl
Steadman Philippon Research Institute, Vail, Colorado, U.S.A.
Travis Lee
TL
Turnbull
Steadman Philippon Research Institute, Vail, Colorado, U.S.A.; Steadman Clinic, Vail, Colorado, U.S.A.. Electronic address: drmillett@thesteadmanclinic.com.
Peter J
PJ
Millett
D000174:Acromion / Q000601:surgery*; D000328:Adult; D001182:Arthroscopy; D002102:Cadaver; D016022:Case-Control Studies; D057645:Deltoid Muscle / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013314:Stress, Mechanical