Vascular and stimulation delays in dynamic musculoplasty.
BACKGROUND
Dynamic musculoplasty is increasingly being used to replace severely damaged muscle. Electrical stimulation induces a change in muscle composition from type II to type I muscle fibers. The aim of this study was to assess the optimal time to start stimulation and the beneficial effect of a vascular delay.


METHODS
Both gracilis muscles in rabbits (n = 3 x 6) were wrapped around a double polyurethane tube, and leads were implanted together with a neurostimulator. Right muscles were electrically stimulated for 11 weeks, and left muscles served as controls. In group 1 the muscle was stimulated immediately after transposition, in group 2 it was stimulated after 6 weeks, and in group 3 a vascular delay was performed and stimulation was started immediately after transposition.


RESULTS
During stimulation the percentage of type 1 muscle fibers increased from a mean of 4.6% to 41.9%. In group 1 there was significantly more change in muscle tissue. There were no significant differences in recorded pressures between groups. In group 1 the increase in amplitude during stimulation was significantly elevated (p < 0.05). The fatigue index in group 1, 259 (SE 130) seconds, was significantly lower than that of group 2, 515 (SE 102) seconds (p < 0.05).


CONCLUSIONS
Compared with the methods used in groups 2 and 3, immediate stimulation (group 1) gives more change in muscle tissue, demanding a higher increase in amplitude to achieve sufficient contraction. The fatigue index is also impaired. Thus vascular delay, as presently applied, does not improve muscle function.
Geerdes
B P
BP
Department of Surgery, Maastricht University Hospital, The Netherlands.
Heineman
E
E
Freling
G
G
Keizer
H A
HA
Woloszko
J
J
Baeten
C G
CG
D000818:Animals; D003094:Collagen / Q000032:analysis; D004558:Electric Stimulation; D005260:Female; D006651:Histocytochemistry; D008297:Male; D009119:Muscle Contraction; D018657:Muscle Fibers, Slow-Twitch / Q000737:chemistry / Q000473:pathology; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000473:pathology; D011817:Rabbits
D003094:Collagen