Complications

What are the potential complications of this fracture?

The Patient's Guide to Fractures gives an account of the problems that can occur during the healing of fractures. These complications include fat embolism syndrome, deep venous thrombosis (DVT), pulmonary embolism and compartment syndrome. Although all these problems can occur with fractures of the humerus they are not especially common. In this section we will consider the complications that occur more frequently.

Malunion

Unless a fracture has been operated on and fixed, it is rare for the alignment of the fracture to be exactly right. Most often this is acceptable but the angulation or rotation at the fracture site can be great enough to cause problems. This would result in inability to lift the arm fully out to the side or fully forward. Because the arm can rotate a lot these restrictions of motion may not be apparent and so may not need to be corrected. However, if they are significant the malunion can be corrected by surgery. This would normally involve an operation to cut the bone and fix it in the corrected position. This amounts to a new fracture with the same long period of healing - so correcting a malunion is not undertaken lightly. If the malunion is treated by surgery one would expect healing and recovery of full range of motion and function.

Nonunion

Delayed union is said to occur when the fracture has not formed bridging callus by three months. This is relatively common but there is still a good chance that the fracture will go on to heal. In rare cases, the bone completely fails to heal. This is called nonunion. This complication occurs most often after cast treatment as the fracture is not immobilized, but it can also occur after surgery. Other risk factors for nonunion include smoking, multiple fragments, poor blood supply, and infection.

A diagnosis of nonunion is a judgement call on the part of the surgeon. It means that in his/her opinion the fracture will not heal unless some further intervention takes place. What happens is that part of the scar tissue laid down between the bone fragments fails to turn into bone. The fracture area remains tender and painful, especially when stressed and sometimes movement between the fragments can still be felt. The X-ray shows a persistent gap between the fragments although sometimes it needs a CT scan to demonstrate this.

Nonunion is normally treated by surgery with removal of the scar tissue from between the bone fragments and rigid fixation of the fracture with a plate or IM rod. Bone graft or other substances which stimulate bone healing is frequently used in this situation. The outcome after treatment of nonunion is normally quite good with the bone healing and function being restored. In a very small proportion of cases the nonunion persists and this causes a very difficult problem of management. The choices are between accepting the situation or continuing to try and find a surgical technique which will solve the problem.

Infection

If the fracture is open it is contaminated at the time of the injury and an infection may result. This is likely to interfere with healing of the fracture and may also cause a long term infection of the bone (chronic osteomyelitis). There is also a small but significant risk of surgical site infection after surgery on a fractured humerus. The wound becomes red, tender and swollen and may discharge pus. The patient often runs a temperature and cultures of the pus or the blood may show evidence of bacteria. High doses of antibiotics are needed for a long period of time. The surgical treatment is to re-operate on the fracture and clean out any dead or infected tissue including dead bone.

Infection is more likely to take hold when the pressure builds up so opening up the site and creating easy drainage for the pus is an important part of the surgery. Antibiotic beads are often inserted into the wound to create a high local concentration of the drug. If the fracture fixation is stable, the implants may be left in place. Surgeons believe that a stable infected fracture is more likely to heal than an unstable one. In some situations the fixation is removed and external fixation is used instead. Once the infection is under control or eliminated it may be necessary to re-operate to fix the fracture and place bone graft. A combination of infection and nonunion is a severe problem.

Once the fracture is healed the fixation is taken out as the presence of non-living material, such as metal, in the region helps the bacteria to avoid the body's defense system. As one can see from this account an infection following a fracture is a serious problem which may require a number of further surgeries. In most cases the outcome is favorable with the bone healed, the infection eliminated and function of the arm restored. Persistent infection in the bone after healing or infected nonunion can cause long term problems.

Nerve Injury

Injury to the radial nerve is quite a common complication of a fracture of the shaft of the humerus. It occurs at the time of the fracture when the broken bone ends are tearing through the tissue of the arm. During surgery on the humerus this nerve is also vulnerable to injury.

There is a spectrum of damage to the radial nerve from injury. Stretching or bruising of the nerve may result in temporary problems. If the nerve is not completely severed, this is called axonotomesis. The overall structure of the nerve is intact. The nerve fibers will re-grow and connect up with their target muscles. This takes a long time and it is important to splint the wrist and hand to prevent contraction of the muscle and joints while they are paralyzed. Nerves grow back at a rate of about 1 mm per day so damage to the radial nerve in the upper arm will take several months to recover.

If the nerve is severed, this is called neurotomesis. Where the nerve is cut completely it needs to be repaired so that regenerating nerves have a chance to grow back in the correct direction. However, there will be persistent weakness because not all the nerves will grow back to the correct muscles.

Related Document: A Patient's Guide to Adult Fractures