Biochemistry and biomechanics of healing tendon: Part I. Effects of rigid plaster casts and functional casts.
OBJECTIVE
Traditional treatment of surgically repaired Achilles tendons includes complete immobilization of the joint in rigid casts for 6 to 8 wk. We tested the use of functional polyurethane casts as an alternative to rigid plaster casts after experimental tenotomy and repair of the rabbit Achilles tendon.


METHODS
After repair the limbs of 15 experimental rabbits were immobilized in a functional polyurethane cast for 15 d, while those of 14 controls were immobilized in traditional rigid plaster casts for the same period.


RESULTS
Functional casting resulted in a 60% increase in total collagen in the neotendon compared with that in rigid casting (P < 0.05). Mature collagen cross-links declined 8% in the tendons with functional casts. The biomechanical parameters of the tendons changed with functional casting, showing a 20% increase in maximum load and 21% increase in maximum stress.


CONCLUSIONS
These changes were noted without any cases of tendon re-rupture in either type of cast. Thus, functional casting following surgery of Achilles tendons appears to improve healing without significant risks of re-rupture.
Stehno-Bittel
L
L
Department of Physical Therapy Education, University of Kansas Medical Center, Kansas City 66160-7601, USA.
Reddy
G K
GK
Gum
S
S
Enwemeka
C S
CS
D000125:Achilles Tendon / Q000293:injuries* / Q000601:surgery; D000818:Animals; D001696:Biomechanical Phenomena; D002370:Casts, Surgical; D003094:Collagen / Q000096:biosynthesis*; D011817:Rabbits; D012421:Rupture; D013708:Tendon Injuries / Q000628:therapy*; D016896:Treatment Outcome; D016474:Weight-Bearing; D014945:Wound Healing
D003094:Collagen