healing bones

Monday, December 2, 2013

Packer Nation and all of Wisconsin have all become experts on bone healing, giving their opinions as to when favorite son, Aaron Rodgers should return to play quarterback after fracturing his clavicle and thus resurrect the failing Green Bay team. If only it was so easy to know when a bone has completely healed. Though most athletes who break their collarbone and return to play within a couple of months, the notion that the bone has completely healed is faulty. While the bone may have regained its strength, healing as defined by x-ray may take 4-6 months and final remodeling and sculpting can take years.

The question is: when can a player or a construction worker or a kid return to their activity and not have an increased risk of reinjuring the same bone, understanding that given the same set of circumstances that caused the fracture in the first place, the bone will still break.

Bone healing is a long physiologic process and the body can fix most fractures by itself. Doctors get involved to try prevent complications, keep bones in alignment and return to the body to function as soon as possible. There are a variety of stages in bone healing and they cannot be rushed.

The first stage is reactive. A blood clot forms at the area of the fracture (remember that fracture, break and crack all mean the same thing, that the integrity of the bone has been compromised) and begins the healing process. Though this clot will eventually dissolve and the cells within it die, it allows the formation of granulation tissue or the matrix that will form the scaffolding for new bone formation. Fibroblasts from each broken end start forming collagen, the body’s building blocks that begin to span the space between the broken edges.

Reparative stage happens next. At the broken bone edges, the outer lining called the periosteum gets turned on, generating chondroblasts that make cartilage and osteoblasts that make bone. They form a mix of bone and cartilage that is not well organized called woven bone and has little strength. However, this mass of bone at the fracture site allows for the real magic of healing to occur. The surface of the callus starts to be pitted by small blood vessels and many more osteoblasts. Instead of laying down random woven bone cells, more formal bony patterns develop into lamellar or cortical bone. This bone is trabecular, meaning that there is a lattice work of bony beams and crossbeams to maintain strength and shape.

The last stage is remodeling, where the body takes the extra amount of bone that has been laid down at the fracture site and slowly sculpts it back closer to its original shape. The trabecular bone is gradually replaced by compact bone in a process that can take up to 5 years. Osteoclasts, cells that break down bone, and osteoblasts, the bone makers, work together during this process.

The wider the gap between the bone edges, the longer the process takes to complete. For that treason, many fractures that had once been allowed to heal on their own are now being considered for surgery. The clavicle or collarbone has been studied extensively since it is so often injured. For displaced fractures where the bones edges are moved apart, surgical repair (also called ORIF for open reduction and internal fixation), seems to have better results than just allowing to have the bone heal on its own. Aside from showing healing more quickly by x-ray, almost 12 weeks faster, patients who had an operation had better function and were happier with the cosmetic result.

Mr. Rodgers had a non-displaced clavicle fracture and needed no surgery, but the healing that needs to occur is still the same and cannot be rushed. When the decision is made to allow him to play and should the bone not have gained enough support and strength to withstand injury, there is the risk that the bone will break again at the same spot.

Aside from clinical judgment by the patient and physician, there is no test to know precisely when the bone is physiologically healed. The clavicle will take many months to heal by x-ray but x-rays usually lag behind the clinical situation. The coach doesn’t know, the sportswriters don’t know and most certainly, Packer Nation doesn’t know. Mr. Rodgers will be cleared to play when the doctor’s gestalt, gut feeling and experience say that he’s ready to go. Meanwhile, Wisconsin can’t wait.



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