A scaphoid fracture is a break in the small bone in the wrist joint called the scaphoid. It is also known as the navicular bone (though this name is most commonly used today to describe a bone in the foot).
While the scaphoid is the most frequently injured carpal bone – accounting for nearly 60 percent of all wrist (carpal) fractures – it is a difficult bone to break and is therefore most often the result of a strong force as in sports (football, basketball, motorcycle racing), or an automobile accident. Twice as much force is required to break the scaphoid bone than one of the bigger forearm bones.
The scaphoid bone is shaped like a cashew and is located on the thumb side of the wrist, near the lower arm bones. Eighty percent of the surface is covered by articular cartilage, and it functions much like a ball bearing in the wrist joint. The unique thing about the scaphoid bone is its blood supply. The blood supply for a scaphoid bone enters from the top, though most fractures occur in the middle or lower portion of the bone. This creates a problem, because the blood supply cannot reach the injury in order to facilitate adequate healing. Sometimes when a scaphoid bone breaks and loses connection with its blood supply, it experiences avascular necrosis – which may cause the bone to crumble and the wrist joint to be destroyed.
Generally injury occurs when the wrist joint of an outstretched hand hyperextends. Men are much more likely to fracture this bone than a woman, because of the forceful activities in which they are often involved and weight ultimately falling or pushing against joint.
When a fracture occurs, pain and tenderness is experienced on the thumb side of the wrist, motion is painful, swelling may be evident on the back and thumb side of the wrist and dull ache my occur periodically. An x-ray of the wrist will detect the fracture – though not always immediately after the break. A bone scan can assist in determining diagnosis just days following the injury.
Often times injuries incurred as a result of high speed or force, such as in football, a fall at high speed or auto accident will result in a complex injury. A complex injury involves companion fractures and ligament injuries as well. A thorough examination will determine whether or not the injury is complex.
Those at Risk
Scaphoid fractures generally occur in men between the ages of 20 and 40 years. It is a common injury in traditional as well as extreme sports. It is also common in motor vehicle accidents.
Often times those sustaining a scaphoid fracture mistake it for a simple wrist sprain, because the bone is located entirely inside the joint and these fractures rarely result in an obvious deformity – as evidenced in the fracture of a forearm, hand or finger bone. And while there may be swelling, that can subside after a few days. The diagnosis of a scaphoid fracture can be delayed for weeks and sometimes months as a result.
Patient history and thorough physical examination assessing pain and wrist posture begin diagnosis. An X-ray will confirm the diagnosis. Magnetic resonance imaging (MRI) may be indicated in order to determine if other tissue damage is present.
Conservative treatment is initially indicated and includes could compression and limb elevation in order to reduce swelling. Most scaphoid fractures are treated with immobilization – with either a splint or short arm cast from six weeks to three months, depending on the severity of the break and associated injuries. Though, casting alone does not always promote healing and in the case of some athletes may impede the rapid return to their sport by restricting the ability to strengthen the area and perform range of motion exercises.
Cast treatment works best for “incomplete” fractures, or those that do not extend across the entire bone. Nondisplaced fractures also have a good prognosis from casting.
Those scaphoid fractures that are “complete” may require a bit more than casting. In some cases either an arthroscopic or open surgical procedure is required in order to stabilize the bone with a scaphoid bone screw, Kirshner wire or other fixation device. Fractures with a severe ligament injury as well require surgery in order to stabilize the wrist and prevent the collapse of the wrist bones – which could cause deterioration and permanent stiffness of the wrist joint.
A fresh fracture (a fracture that is less than two to four weeks old) that is displaced or unstable requires surgery and the use of a fixation device for stabilization. A fracture that is not first stabilized is unlikely to heal in a cast.
Nonunions and Old Fractures
An untreated scaphoid fracture can result in severe arthritis and eventually require surgery to fuse or replace the joint. A nonunion of the bone, or a bone that has failed to heal, and old fractures, require special treatment.
Sometimes a bone graft is necessary to prompt the healing of an old scaphoid bone fracture that has never healed. A small piece of bone is taken from the iliac portion of the pelvic bone in order to stimulate healing of the old fracture. A Herbert scaphoid screw is used to stabilize the bone graft and the patient is put in a cast for approximately four weeks. Occasionally a fresh fracture will also require a bone graft when there are a number of pieces, or it is “comminuted.”
If a wrist was immobilized with casting, the patient will begin a series of range of motion exercises upon the removal of the cast. These exercises are very important for limbs that have been immobilized for any length of time – as joints become stiff and muscles weakened. A thumb spic splint may be used for protection until range of motion and strength of the wrist flexors and extensors improve. Supination, pronation, and grip exercises are progressively added.
If a long-arm cast is used and flexion contractures are evident, physical therapy will be recommended and a program specific to the patient will be developed.
Following surgery with internal fixation, patients are instructed to keep their wrist elevated for the first couple of days and to keep clean, dry bandages on the surgical area. Swelling is reduced with cold compressions. And analgesic medications may be prescribed to help minimize postoperative pain.
Following an arthroscopic procedure and period of immobilization, range of motion exercises begin, but may vary on the patient and condition of the wrist following certain surgeries. Patients are then given progressive strengthening exercises for the wrist flexors and extensors – with supination, pronation and grip exercises gradually added.
Generally, once a fresh fracture is stabilized with fixation, the patient may return to sports in approximately eight weeks. Though following a nonunion and bone grafting, the recovery process may last up to three months.