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When the Thomas splint is not to be had, plaster can be used for the same purpose. The usual spica is applied from the lower ribs to the ankle, particular care being taken to mould an accurate support for the tuberosity of the ischium (see p. 35). Into the lower portion of the plaster, a strong bar of iron bent so as to form a loop, projecting 4 inches beyond the patient's heel, is incorporated by several extra turns of the plaster bandage (see Fig. 20). The patient can walk in this without bringing his weight to bear on the bone.
In fractures of the bones of the calf, I have never found it necessary to remove weight-bearing entirely, since sufficient support is given by a light circular plaster-of-Paris dressing or by a light splint consisting of two steel uprights affixed to the patient's boot. When there is any tendency to a valgus deformity, the outside iron and Thomas heel, as advocated by Jones, are indispensable.
Methods of Mobilization.-In almost all gunshot injuries to the bones, adhesions form during the period of immobilization. We have already seen how these can be prevented in the case of fractures of the femur and of the humerus. In many cases, however, despite the earliest possible discontinuance of immobilization, adhesions are present, preventing the free play of the muscles and hindering the motion of the joint. Their treatment will be considered when discussing injuries to joints.
Non-union of Fractures.—This occurs more frequently after gunshot injuries than in other types of fractures, owing to the extensive loss of osteogenetic tissue commonly caused by the projectile. Care on the part of the surgeon in conserving all tissues capable of bone regeneration, frequently produces good results under circumstances which at first seemed hopeless. Thus Fig. 41 illustrates an injury to the humerus, in which the splinters of the shaft lay fully exposed at the bottom of a severely infected extensive wound. None of the bone fragments were removed, although many of them were attached by only a few shreds of periosteum. Within three months solid bony union had occurred.
In many instances, however, despite this attempt to conserve, non-union results. The methods of treatment do not differ from those employed in the pseudo-arthroses subsequent to fractures produced by indirect violence.
Non-operative Treatment.—When it is possible without operation, to bring the bone ends together, an attempt to bring about union should be made:
Fig. 41.–Gunshot injury to the upper end of the humerus. None of the bone splinters were removed, although the wound was severely infected. Healing in ten weeks without shortening or other deformity.
(a) By vigorous rubbing of the bone ends so as to stimulate osteogenesis, followed by
(6) Absolute immobilization in a splint which exercises uniform pressure at the site of the fracture. In the case of the upper extremity where moderate shortening is of little significance the splint should press the bone fragments together, even if there is a hiatus of 1 or 2 inches between them. In the lower extremity the splint should be so constructed as to allow weight-bearing, at the same time supporting and immobilizing the fragments, since the body-weight frequently conduces to bone production.
(c) In addition, the Thomas method of "hammer and dam" should be vigorously followed. A rubber compression bandage is applied above and below the site of injury, and the periosteum traumatized with a hammer.
This non-operative treatment should be pursued for at least three months. If then there is no improvement, operation is indicated.
Operative Treatment.—Non-union of fractures is best treated by bone-implantation. Few subjects in recent years have attracted more attention than this, and much careful experimental work has been done to decide the fate of the graft and to determine the most physiological operative procedure. The classical research of Ollier has been confirmed by Axhausen, who showed conclusively the superiority of autoplastic transplanted bone to homoplastic or heteroplastic, of living bone to dead, of periosteal-covered to bone stripped of the periosteum. The osteogenetic importance of the periosteum has been challenged by Macewen ("The Growth of Bone," 1912). On the basis of animal experimentation and clinical experience he maintains that the periosteum acts merely as a limiting membrane and that the bone growth comes from the bone cells which possess a vegetative capacity fully as great as that of the epithelial cells. An experimental study of Macewen's work, however Mayer and Wehner: Archiv für Klinische Chirurgie, Bd. 103, Heft. 3) has created some skepticism as to the correctness of his views. To test Macewen's claim that there is an outpouring of osteoblasts from the bone after the periosteum has been removed, Mayer and Wehner performed the following experiment: The periosteum was stripped from the surface of the tibia (rabbits and dogs were used), and a small cap of glass or steel fastened firmly to the surface of the bone, so as to exclude the periosteal cells from the denuded surface of the tibia (see Figs. 42 and 43). Were Macewen's view correct, bone production would occur beneath the cap.
Fig. 42.–Schematic, longitudinal section of tibia, illustrating the principle of Mayer and Wehner's "cap xperiment.” The cap was fastened directly to the denuded cortex of the tibia allowing an ample air space into which osteoblasts could migrate, were Macewen's theory as to their genesis, correct. a, Groove in the cortex, to which the cap, b, was fastened by a wire (see Fig. 43); C, the cortex denuded of periosteum; d, periosteum.
The experiment showed that in all those instances, in which the periosteal cells were completely excluded by the cap, no regeneration of the bone took place, whereas in those instances in which, owing to the presence of a minute gap between the cap and the bone, the periosteum was given a chance to grow in, osteogenesis occurred (see Figs. 44 and 45). The further experiments of Mayer and Wehner emphasized the correctness
Fig. 43.-Photograph illustrating the manner of attaching the little caps to the denuded surface of the tibia. This experiment of Mayer and Wehner tested the osteogenetic function of the cortical bone, and proved the incorrectness of Macewen's contention that the osteoblasts issue from the interior of the bone.
of Ollier's teaching: that the most important osteogenetic cells are those lying between the outer fibrous layer of the periosteum and the surface of the bone—the so-called cambium layer of the periosteum. The osteogenesis observed in cases of bone