Jacqueline Wallace, of Phoenix, sat enjoying the December 1993 holidays at her son's home in Gaithersburg, Md. But when she stood up and took a step, her holiday took a turn for the worse. Wallace fell and fractured her hip.
"My foot
dragged a little, not exactly a stumble," Wallace says. "I don't know whether the bone broke because I fell, or I fell because the bone broke."
Despite her 84 years and weak heart, Wallace had a lot going for her after her fall: modern medical practice and determination to walk again. Surgery to implant an artificial hip joint took under 45 minutes. (The x-ray at left shows the artificial left hip in sharp contrast with the bones of the normal right hip.) Spinal
anesthesia and sedation were administered instead of general anesthesia because they are thought to pose less risk. And her physical therapy began the day after the operation.
"I fussed," she says. "I was afraid it was going to hurt or I'd fall. But they said if you want to go home, you have to do this. And I did. It was more scary than painful." Wallace's fracture was one of 1.5 million--including 336,000 hip fractures--reported in 1993, the latest year for which the National Center for Health Statistics has figures. Besides surgical repair, treatments for broken bones include bone manipulation to reduce the fracture, use of a cast, and bone stimulation.
Central to fracture healing is bone biology. Many treatments, some on the horizon, are designed to improve the natural course of healing. Bones at Work
For skeletal growth and maintenance, the body's 206 dynamic, living bones renew themselves lifelong through a continual breakdown, build-up process known as remodeling. This process is also involved in the
remodeling of fractures, says Martin Yahiro, M.D., a Baltimore orthopedist in private practice and a consultant on fracture treatment devices to the Food and Drug Administration's Center for Devices and Radiological Health. In remodeling, complex chemical signals prompt cells called osteoclasts to break down and remove (resorb) old bone, and others called osteoblasts
to deposit new bone. Many elements influence remodeling. Among them: weight-bearing, vitamin D, growth factors, prostaglandins, and various hormones, including estrogen, thyroid, parathyroid, and calcitonin. As 80 percent of the mature skeleton, compact cortical bone supports the body, providing extra thickness mid-shaft in long bones to prevent their bending.
Cancellous bone, whose porous structure with small cavities resembles a sponge, predominates in the pelvis and the 33 vertebrae from the neck to the tailbone. A fibrous membrane called the periosteum covers bone. For healing and health, living bone must have a steady supply of nutrients. Blood vessels permeate bone to provide this lifeline. Blood-forming elements fill
the long bone inner canals. When a Bone Breaks
Fracture breaks continuity of bone and of important attached soft tissue--including blood vessels, which spill their contents into surrounding tissue. Even before treatment, the body
automatically seeks to repair the injury. Inflammatory cells rush to destroy, dilute or isolate invaders and injured tissue. Tiny new blood vessels called capillaries begin growing into the site. Cells proliferate. The injured person usually must endure pain, swelling, and increased heat at the breakage site for one to three days. New tissue bonds the fractured bone
ends with a soft callus, a mass of connective tissue and exudate (matter escaped through blood vessel walls). Remodeling begins. Within a few months, a hard callus replaces the soft one. Remodeling restores the inner canal. Once restoration is complete, which may take years, the healed area is brand new, without a scar. Usually thicker, the new bone may even be
stronger than the old, Yahiro says, adding that if the bone should break again, it's unlikely to be at the same place. And children's bones have a healing boost: They're growing. "The growing skeleton is just geared to make bone,"
Yahiro says. "A very young child's wrist bones grow a millimeter a month, to rapidly correct misalignment or length defects. An adult may take six to eight weeks to heal a wrist fracture, a 5-year-old only three." When the ends of a fractured bone, such as an arm bone, form an abnormal angle, the doctor must decide whether to push the ends together
(manipulation) to reduce the fracture, possibly under anesthesia. Simple x-rays aid evaluation. "If it's a large angle, we'd want to reduce that fracture," Yahiro says. "But if it's a small angle, especially in a young child whose growth will correct it, we'd probably just put the limb in a cast." . |
