When a bone is fractured, it recovers when new bone tissue forms to fill in the cracks. However, in some instances this recovery does not go smoothly, and as a result there are “non-unions” in the bone. Non-union is failure of bone healing. These non-unions occur when new bone tissue does not grow to bridge the fractures. This can happen when a bone is not well stabilized or doesn’t receive ample blood to allow the new tissue to grow, or if the fracture has an infection. Non-unions occur for a variety of reasons. They are caused by patient-related factors, fracture-related factors and fixation-related factors.
The FDA defines non-union as “established when a minimum of six months has elapsed since fracture with no visible progressive signs of healing for three months.” This serious condition is not common but can lead to further complications. If a patient feels that a previously fractured bone did not heal properly, he/she should consult an experienced surgeon like Dr. Louis, who has years of experience treating non-unions.
The signs of non-union include persisting pain and/or tenderness at the fracture sight, lack of mobility and the inability to resume daily function with that particular body part. Slight warmth of the skin and swelling may be detected if at the fracture site.
The two major types of unions are hypertrophic and atrophic.
- Hypertrophic – If a non-union has resulted from a mechanical issue at the fracture site despite good healthy tissue and fracture biology, the result may be a hypertrophic non-union. The sign of a hypertrophic mal-union is a bulging appearance at the fracture site, which results from a large amount of callus formation. This is often called “elephant foot” because of its appearance. While the blood supply is still good and there is adequate healing, the bulky appearance is a sign of motion at the facture site. Surgery for this condition is aimed to rigidly fix and stabilize the fracture by causing compression of the two fragments.
- Atrophic – Atrophic non-union is seen radiologically by narrow, rounded ends of bone at the level of the fracture. This is caused by a poor healing response due to a lack of blood supply. Because of this, the treatment of an atrophic non-union is more complicated than with hypertrophic non-union. The fracture must be held in place, then the tissue around the bone ends is removed and the avascular bone ends are hollowed out back to healthy bone. Then bone graft is packed around the fracture area.
Complications such as limb shortening or a gap between the fracture ends may be seen more frequently with atrophic non-union as treatment initially resects non-viable bone back to healthy bone.
Treatment of non-unions may be complemented with a synthetic bone graft or one that is obtained from the patient or from another individual (also known as a donor graft). Newer approaches are using special proteins called recombinant bone morphogenic protein and bone marrow aspirates. Bone marrow may be harvested from the individual’s pelvic bone or femur and injected directly into the fracture site guided by external imaging. If there is an infection, it will require surgical removal of any infected bone or tissue, followed by intensive antibiotic treatment.
Non-union conditions often require a long healing period after surgery, and depending on the physical condition of the patient and the extent of the complication, it can sometimes take a few surgeries to fix the problem. Rehabilitation often requires a patient to not bear weight on the affected leg for several weeks, similar to when the initial injury occurred.