by Augusto Sarmiento, MD
Fifty-five years after completion of my residency I have finally stopped working at the University and Hospital. It was a painful decision, precipitated by the deteriorating health of my wife. We ended up leaving Miami and moving to Punta Gorda, a small community in Southwest Florida. Only four months have passed since my new life began, so I hope additional time will assuage the profound unhappiness I now experience from not being able to teach orthopaedic residents.
Trying to identify topics that I could dwell on with some confidence and share with my colleagues, I quickly ran into fracture healing and care, because since the early 1960’s I worked on these subjects with great enthusiasm and perseverance. I first published my initial work on what I considered the positive role that motion plays in fracture healing. The concept was severely criticized in orthopaedic/scientific circles as being anathema to well-established principles. At that time, the AO, a powerful scientific/commercial organization, was making rapid advances in marketing the use of surgical appliances aimed at obtaining rigid immobilization of fracture fragments, which they considered to provide the best and most expeditious environment for healing.
More than one hundred publications from our laboratories and clinics at the Universities of Miami and Southern California have solidified my firm belief that diaphyseal fractures rather consistently heal, not because they are rigidly immobilized but despite the immobilization. Rigid immobilization deprives the injured bone from the stresses that every tissue in the body must be subjected in order to maintain desirable biological and mechanical properties.
Following the initial injury there is bleeding at the fracture site, a phenomenon that has led some to mistakenly believe that the hematoma plays a role in osteogenesis. However, there is nothing to support such a mythological idea. Quite the contrary, it is likely that the hematoma is an obstacle to healing and must be gradually absorbed. If that were not the case, we should be injecting blood into fractures in order to enhance healing.
When a fracture is not rigidly immobilized and the injured limb is subjected to the gradual stresses that come from the gradual introduction of muscle activity, as well as motion of the extremity, a massive capillary invasion at the level of the fracture takes place. (Figs. 1.a. & b.).
This vascular phenomenon is the single most important one in the process of fracture repair because the perithelial and endothelial cells of the capillaries undergo osteoblastic metaplasia and form peripheral callus.(Figs. 2.a. & 2.b.).
In the rigidly immobilized fracture the healing occurs from growth of osteons but without peripheral callus. Mechanically, the strength of a callus is measured by the diameter of the callus.
The next related important observation is the fact that in fractures of both bones in the lower leg and forearm the initial shortening experienced does not increase with the gradual introduction of weight bearing activities. The interosseous membrane, an elastic structure, prevents the increase in shortening while still permitting elastic pistoning. (Fig. 3a and 3b). Needless to say, fractures with extensive damage to the membrane experience greater shortening and lack the benefits of acceptable of the initial shortening or the maintenance of manually corrected length.
I am not aware of any work that has negated the validity of the observations I have just made. Furthermore, I am keenly aware of the many advantages that surgical stabilization possesses, which explains the fact that despite its biological negative features, it is taught to current generations of orthopaedists as the only sound approach to fracture management. A logical balance between the two opposing schools is necessary since there is a place for both of them. Economic considerations should not be ignored.
Dr. Sarmiento is the former Professor and Chairman of Orthopaedics at the Universities of Miami and Southern California, and past-president of the American Academy of Orthopaedic Surgeons. He is a contributor to Implant Identification on OrthopaedicList.com and has guest authored a number of other articles for this blog.