670 WOUND HEALING 8 



It is now established that the tensile forces controlling the degree of contraction 

 are derived from granulating tissue and are not due to a sphincter type action of the 

 wound perimeter (Hegemann, 1950). Carrel (1920, 191 2) noted that the latent 

 period for contracture was essentially the same as for granulation formation and 

 assumed that it was due to shrinkage of this newly formed tissue. Granulation 

 tissue has been aptly described by Billingham and Russell (1956) as an "organ of 

 contracture," and its ultimate fate is directly dependent on the skin mobility of 

 the area. 



Two theories exist to explain the origin of tensile forces within the granulating 

 base. The first states that it is derived from formation and subsequent short- 

 ening of collagen fibers (Gaza, 191 8: Kaufmann, 1922). This viewpoint has been 

 well presented by Lindquist (1946), who assumed that fibers may shorten or 

 become kinked during maturation. The second theory is based upon evidence that 

 connective tissue cells are the contractile mechanism. Abercrombie et al. (1954) 

 demonstrated that collagen formation in the rat, when measured by hydroxypro- 

 line determinations, did not parallel the course of contraction. More recently they 

 have shown (Abercrombie et al., 1956) that wounds on scorbutic guinea pigs 

 undergo normal contracture despite a failure to form collagen. These findings 

 have led to the conclusion that connective tissue cells of granulation tissue play 

 the important role in initiating tensile forces. Neither reticvdin nor collagen fibers 

 possess contractile ability under physiological conditions. This is a property of the 

 cell, however, and can be demonstrated well in vivo with muscle or in tissue culture 

 with a variety of cell types, including fibroblasts. The amount of granulation 

 tissue seems to bear little relationship to the degree of contraction. Wounds that 

 granulate excessively {e.g. burns) contract no more than excised wounds involving 

 the same area. The degree of contracture appears to be related directly to mobility 

 of the skin and its underlying tissues. 



Attempts to measure the degree of wound contracture were first carried out by 

 Carrel and Hartmann (1916) and Du Noiiy (1916, 1919, 1932, 1936). Since then 

 the literature on this subject has become rather extensive (Lumiere, 191 7, 1918a, 

 b; Faure-Fremiet and Vies, 1919; Brummelkamp, 1919; Backman, 1931; Lind- 

 quist, 1946), but the results are confusing and difficult to evaluate. Burrows (1924) 

 reported that the speed of contraction progressively increases, while Du Noiiy 

 (1936) states the opposite view. This controversy has been re-evaluated recently 

 by Billingham and Russell (1956), using standard-sized wounds in rabbits. They 

 found that a linear relationship existed between the 6th and 40th days when the 

 greater part of closure took place. The initial wound always retracted because of 

 elasticity of the adjacent skin, and contracture did not commence until approxi- 

 mately the 4th day, when granulation tissue began to form (Loeb, 1920; Burrows, 

 1924; Fuke, 1932; Lanber, 1933; Eitel and Riecker, 1936; Young et al., 1941). 

 Similar results have also been reported by Van den Brenk (1956) who studied 

 circular wounds on the flank of rabbits. He found that regardless of the size 

 of the defect, there was a constant absolute linear rate of contraction for the 

 major portion of the healing period. These recent reports confirm the previous 

 results of Henshaw and Meyer (1944). In wounds excised to the level of the 

 panniculus carnosus the latter served as a base for the contracting superficial 



