Introduction
Scaphoid fractures can be challenging. They are often missed on initial x-rays, and even when treated promptly they can sometimes fail to heal. Scaphoid non-union can be painful and progress to wrist arthritis. In simple cases, bone grafting can result in union, but when there is also interruption of the scaphoid blood supply, reconstruction of the scaphoid with vascularised bone grafting offers a reliable solution.
Indications
In cases of scaphoid non-union where the joint surfaces are preserved, but there is a problem with the blood supply, a vascularised bone graft from the inside of the knee (medial femoral condyle flap or MFC) can achieve healing of the scaphoid where other procedures often fail. Even in some cases where part of the scaphoid has collapsed, a variation of this procedure (the medial femoral trochlea flap or MFT) can replace that half of the scaphoid and preserve wrist function.
Preoperative Instructions
MFC and MFT procedures are done under general anaesthetic, usually with addition of a nerve block of the arm. Usually 2-3 nights in hospital are required. Any blood thinning medications would need to be stopped in consultation with your doctor.
Procedure
An incision is made in the wrist and the scaphoid is prepared and the blood vessels in the wrist are dissected. An incision is then made on the inside of the knee, and the piece of bone and the blood vessels are dissected. After harvesting the bone from the knee, the wound is closed over a drain. The bone block is then secured to the scaphoid with a screw and x-rays are taken. The blood vessels to the transferred bone are then repaired to the vessels in the wrist.
Postoperative Instructions
The wrist is immobilized in a plaster for 2 weeks and then changed to a cast for another 2 months, after which a CT scan confirms healing of the scaphoid. You are able to walk the day after the surgery but there is some discomfort for several weeks.
Risks
Given the donor site in the knee there is a small (<5%) chance of some knee pain persisting beyond the first 6 months after the surgery. Although the healing rate of the reconstructed scaphoid is very high, there is still a risk of developing degenerative arthritis in the long term.
Treatment Alternatives
Other options for complex scaphoid nonunion are arthroscopic bone grafting, rib grafting or wrist fusion or replacement.