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Chapter 13

Battle Casualties in Korea: Studies of the Surgical Research Team Volume III

The Criteria for Determining the Viability of Muscle in War Wounds

Captain Robert E. Scully, MC, USAR
Lieutenant Colonel Curtis P. Artz, MC, USA
Captain Yoshio Sako, MC, USAR

One of the prime requisites of adequate initial surgery in war wounds is the removal of all devitalized tissue. When all devitalized tissue is removed, delayed primary closure can be carried out in 4 to 6 days. On the other hand, necrosis results if devitalized muscle is allowed to remain in the wound. Necrotic tissue serves as a stimulus to bacterial growth with subsequent local infection, septicemia, or clostridial myositis; and in some instances it causes death.

Determination of the viability of muscle soon after wounding is difficult. Thorough débridement in large wounds is a real problem even for the most experienced wound surgeon. A surgeon who has had considerable experience in débriding wounds has developed sufficient clinical judgment to accomplish a good débridement. The exact criteria used vary with the surgeon, as they are based on individual experiences. Some surgeons determine viability at operation primarily by contractility of the muscle, some place greater emphasis on the ability of the muscle to bleed, while others judge the condition of the muscle by its color and consistency.

It appears that there are four criteria-color, consistency, contractility, and bleeding-which may be used to determine the viability of muscle. This study was initiated in an attempt to evaluate the importance of each of these criteria.

Materials and Methods

Sixty biopsies of muscle of questionable viability were taken from war wounds of various regions of the body by two surgeons at the time of initial débridement. The average time from injury to surgery was 6 hours. The muscle was observed carefully before biopsy and graded as to color, consistency, contractility, and bleeding. Whenever possible, both surgeons corroborated in grading the specimen. Observations made for color were: dark red, red, pale, or pink. Pink was used as the color of normal, noninjured muscle. Gradations


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of consistency were mushy, stringy, soft, and firm; and they were determined by grasping the tissue with forceps and observing the character of the muscle. Sometimes it was difficult to grade the amount of contractility. The muscle mass was pinched with a forceps and its reaction observed and graded 0, 1+, 2+, or 3+. Normal muscle bleeding was graded as 3+. The biopsies were put in a saline solution for 20 minutes, then fixed in 10 percent formalin. The pathologist received each specimen with a clinical note stating its gradation as to color, consistency, contractility, and bleeding.

The individual biopsies varied from 1-2 cm. in diameter. Each one was examined following fixation by the pathologist; and it was cut with a sharp scalpel blade if trimming was necessary. The tissues were carried through paraffin embedding and were stained with hematoxylin and eosin. The pathologist examined and interpreted the specimens independently of the surgeon's description of the muscle. Each biopsy was graded according to an estimation of the percentage of damaged muscle in the total specimen, with ranges as follows:  none to minimal damage, 0-10 percent; slight damage, 11-33 percent; moderate damage, 34-66 percent; marked damage, 67-89 percent; complete or almost complete damage, 90-100 percent.

Results

Microscopic Findings

The qualitative degree of damage in the débrided muscle exhibited a wide range. Because of the fine shading of the various types of damage into one another, it was decided to grade the damage quantitatively and not qualitatively. The least evidence of muscle injury was separation of individual fibers from one another. Since this finding is a common artefact in tiny fragments and along the borders of large fragments, it was the most difficult to evaluate and was therefore interpreted cautiously. Fortunately only a few specimens fell into this category.

A muscle injury considered somewhat severe was the separation of fibers and degenerative changes in individual fibers manifested by nuclear pyknosis and various alterations in the sarcoplasm. These alterations included: (1) waxy degeneration, indicated by fibers which had taken on a homogeneous, deeply eosinophilic hue, and, (2) sarcoplasmic shredding, manifested by the sarcoplasm being contracted into coarse reticular masses so that the remainder of the sarcolemmal tubes were filled with slightly basophilic fluid.

The last two forms of muscle degeneration offered difficulties in interpretation, since they were occasionally present as artefacts at the cut edges of the muscle fragments. The discoid type of degeneration which is observed in ischemic muscle was not seen in these me-


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chanically damaged muscles. The most advanced changes noted in the injured muscle were marked blurring of the internal structure of the fibers, with advanced pyknosis, and disappearance of nuclei. These fibers were most often ballooned into swollen masses widely separated from one another. The endomysial framework of such muscle was frequently disrupted, with a disorderly arrangement of the fragmented fibers. This advanced form of degeneration undoubtedly represents irreversible necrosis.

Other findings in the biopsies were edema, polymorphonuclear leukocyte infiltration and hemorrhage. The presence and distinctness of the cross-striations were of little help in judging the degree of muscle damage. Although the striations were seldom recognizable in the most advanced forms of necrosis, frequently they were sharper and more clearly visible in obviously damaged muscle than in apparently normal muscle. These changes tended to be most marked in the perimysium, and they appeared to a lesser extent in the endomysium. They were rarely diffuse, although occasionally they were intense focally. Their presence alone was not considered indicative of muscle degeneration.

No observations were made of intravascular accumulations that could be identified with certainty as thrombi; however, it is probable that many of the intravascular red-cell clumps were actually thrombotic. The vessels, especially the veins, often showed striking polymorphonuclear infiltrations of their walls. Another finding of interest was the structural replacement of large portions of disrupted vascular wall by coagulums of fibrin, platelets, and a few cells.

Surgical Pathologic Correlation

Table 1 presents the over-all correlation of surgical criteria for muscle damage, with the amount of damage observed microscopically.  Plotted from Table 2, the probit shows excellent linearity (Fig. 1). Thus, the population of the specimens was a statistically normal one.  This finding adds weight to the reliability of the results.

Correlation coefficients were computed for the relationship between the various surgical criteria in each category: color, consistency, ability to bleed, contractility, and the amount of muscle damage observed microscopically. These coefficients are shown in Table 3. The best correlation between the surgical criteria and the amount of damage observed microscopically by the pathologist was found in the consistency category. However, the correlation was almost as significant in the categories of ability to bleed and contractility. Correlation between color changes and the amount of microscopic damage was doubtful from the standpoint of statistical evaluation of the data.


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Table 1.  Correlation of surgical Criteria with Damage Observed Microscopically


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Table 2.Computation of Probit Line Plotted from Data in Table 1

FIGURE 1.  Probit line plotted from data in Table 2. The linearity shown here points out the normality of the population of specimens that were examined.

In general, the studies showed that there are three valid criteria for determining the viability of muscle: consistency, ability to bleed, and contractility.

Discussion

There are several obvious defects inherent in using pathologic criteria to determine muscle viability. It is possible that muscle, which appears normal on routine staining with hematoxylin an eosin,


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Table 3.Correlation Coefficients from Analysis of Data in Table 1

may actually be in the initial stages of irreversible necrosis. Moreover, muscle showing minor to moderate degrees of regeneration probably is capable of restoration to normal. Despite these possibilities, it is logical to assume that the actual degree of degeneration and necrosis, in general, parallels the microscopically observed severity of damage, and that morphologic changes are valid criteria for comparative evaluation of viability.

The biopsies in this series were taken from 3 to 8 hours after wounding. The time factor did not seem important, as the muscle specimens taken 3 hours after wounding were capable of showing the same grades of clinical and pathologic damage as those taken at 8 hours.

A second defect inherent in the method is the difficulty in quantitating selectively the various qualitative types of muscle damage observed. The biopsies showed degrees of damage ranging from mild to severe. Although the damage most often involved diffuse areas, occasionally it was manifest as focal fiber damage.

A third clinical difficulty is the variation of terms used by individuals to express the surgically observed characteristics of a small section of muscle. For this reason, any results of such a study must be interpreted by each surgeon in the light of his own personal experiences in débriding wounds. A further refinement in this type of evaluation would be a careful clinical follow-up of the wounds by the surgeon, possibly with additional biopsies made on an area near that of the original ones. This procedure would give an indication as to the ultimate outcome of the muscle tissue in that area.

It is well recognized that it is most difficult for the surgeon to make a decision as to the viability of muscle, and it requires considerable experience. Most surgeons  gain insight into the problem by re-evaluating the efficiency of their débridement upon examination of the wound 4 or 5 days after the initial operation. Judgment improves


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after several experiences of this type; and a better initial débridement is carried out.

Although the results of this study are limited, they indicate that there is a statistically significant correlation between consistency, ability to bleed, contractility, and the amount of damage that is observed microscopically. There is sufficient evidence to show that a muscle is viable if it is firm, if it bleeds when cut, and if it contracts when stimulated.

Summary and Conclusions

Preliminary study was carried out to observe the criteria for the viability of muscle in wounds requiring débridement.

Sixty biopsies were taken from 12 war wounds from 3 to 8 hours after injury. Each portion of muscle observed was graded by two surgeons according to color, consistency, ability to bleed, and contractility. The pathologist graded each specimen independently to determine the amount of necrosis: minimal, slight, moderate, marked or complete. These biopsies were taken from areas of questionable necrosis; and they were estimated quantitatively only and then correlated with these various surgical criteria.

A statistically significant correlation was obtained for three criteria: consistency, ability to bleed, and contractility. Color was of doubtful value in determining the viability of muscle.