What are scaphoid fractures?
The scaphoid bone is one of the eight small bones that make up the “carpal bones” of the wrist. There are two rows of bones, one closer to the forearm (proximal row) and the other closer to the hand (distal row). The scaphoid bone is unique in that it links the two rows together (see Figure 1). This puts it at extra risk for injury, which accounts for it being the most commonly fractured carpal bone.
How do scaphoid fractures occur?
Fractures of the scaphoid occur most commonly from a fall on the outstretched hand. Usually it hurts at first, but the pain may improve quickly, over the course of days or weeks. Bruising is rare, and there is usually no visible deformity and only minimal swelling. Since there is no deformity, many people with this injury mistakenly assume that they have just sprained their wrist, leading to a delay in seeking evaluation. It is common for people who have fractured this bone to not become aware of it until months or years after the event.
Diagnosis of scaphoid fractures
Scaphoid fractures are most commonly diagnosed by x-rays of the wrist.
However, when the fracture is not displaced, x-rays taken early (first week) may appear negative. A non-displaced scaphoid fracture could thus be incorrectly diagnosed as a “sprain.” Therefore a patient who has significant tenderness directly over the scaphoid bone (which is located in the hollow at the thumb side of the wrist, or “snuffbox”) should be suspected of having a scaphoid fracture and be splinted (see Figure 2).
An X-ray a couple of weeks later may then more clearly reveal the fracture. In questionable cases, MRI scan, CT scan, or bone scan may be used to help diagnose an acute scaphoid fracture.
CT scan and/or MRI are also used to assess fracture displacement and configuration. Until a definitive diagnosis is made, the patient should remain splinted to prevent movement of a possible fracture.
Treatment of scaphoid fractures
If the fracture is non-displaced, it can be treated by immobilization in a cast that usually covers the forearm, hand, and thumb, and sometimes includes the elbow for the first phase of immobilization. Healing time in a cast can range from 6- 10 weeks and even longer.
This is because the blood supply to the bone is variable and can be disrupted by the fracture, impairing bony healing.
Part of the bone might even die after fracture due to loss of its blood supply, particularly in the proximal third of the bone, the part closest to the forearm.
If the fracture is in this zone, or if it is at all displaced, surgery is more likely to be recommended.
With surgery, a screw or k wire/pins are inserted to stabilize the fracture, sometimes with a bone graft to help heal the bone.
Surgery to place a screw may also be recommended in non-displaced cases to avoid prolonged casting.
Current evidence suggests vascularized bone grafting does not yield significantly superior results to non-vascularized grafting in scaphoid nonunion management.
The fixation type or source of the graft used was not found to influence union rates either.
Whether your treatment is surgical or nonsurgical, you may be required to wear a cast or splint for up to 6 months or until your fracture has healed. Unlike most other fractures, scaphoid fractures tend to heal slowly. During this time, unless advanced activity is approved by your doctor, you should avoid the following activities:
Lifting, carrying, pushing, or pulling more than one pound of weight
Throwing with your injured arm
Participating in contact sports
Climbing ladders or trees
Participating in activities with a risk of falling onto your hand, such as inline skating or jumping on a trampoline
Using heavy or vibratory machinery
Smoking (which can delay or prevent fracture healing)
Some patients have wrist stiffness after scaphoid fractures. This is more common in patients who wear a cast for a long time or require more extensive surgery.
It is important to maintain full finger motion throughout your recovery period. Your doctor will provide an exercise program, and may refer you to a trained hand therapist who will help you regain as much range of motion and strength in your wrist as possible.
Despite hand therapy and a great deal of effort by the patient during home therapy, some patients may not recover the same range of motion and strength that they had before their injury.
A bone that fails to heal is called a "nonunion." Nonunions are more common after scaphoid fractures because the blood supply to the scaphoid bone is poor. Good blood supply to a bone is very important in fracture healing—since blood carries oxygen and nutrients to the site of the fracture to aid in healing.
If your scaphoid fracture does not heal, your doctor may consider surgery to insert a bone graft. There are several types of bone grafts. For nonunions, your doctor may use a special kind of graft with its own blood supply (vascularized graft). In the case of a fracture that has collapsed, your doctor may use a structural graft--possibly from your hip.
In scaphoid fractures—especially those in which the bone fragments have become displaced—the blood supply to the bone may be disrupted. If the blood supply to one of the fragments is reduced significantly or lost completely, that fragment of bone will not get enough nutrients and the cells will die. The bone will not heal properly if this occurs. This condition is called "avascular necrosis."
A vascularized bone graft is the most effective treatment for this condition—providing the bone has not collapsed significantly or arthritis has not developed in the wrist.
Over time, nonunion and avascular necrosis of the scaphoid can lead to arthritis of the wrist. Arthritis occurs when the articular cartilage in the joint becomes worn and frayed—sometimes to the point where bone rubs on bone.
Symptoms of arthritis in the wrist may include:
Decreased range of motion in the wrist
Pain with activities such as lifting, gripping, or weight bearing
Treatment for arthritis focuses on improving symptoms. At first, this may include taking anti-inflammatory medicine or over-the-counter analgesics, wearing a splint when the wrist is painful, and avoiding activities that aggravate the wrist. Sometimes, a steroid injection into the wrist may help relieve pain.
If conservative treatment does not relieve your symptoms, your doctor may recommend surgery. There are many types of procedures that can be performed for wrist arthritis.
Complications of scaphoid fractures
Non-union: If a scaphoid fracture goes unrecognized, it often will not heal. Sometimes, even with treatment, it may not heal because of poor blood supply. Over time, the abnormal motion and collapse of the bone fragments may lead to mal-alignment within the wrist and subsequent arthritis. If caught before arthritis has developed, surgery may be performed to try to get the scaphoid to heal.
Avascular necrosis: A portion of the scaphoid may die because of lack of blood supply, leading to collapse of the bone and later arthritis. Fractures in the proximal one third of the bone, the part closest to the forearm, are more vulnerable to this complication. Again, if arthritis has not developed, surgery to try to stabilize the fracture and restore circulation to the bone may be attempted.
Post-traumatic arthritis: If arthritis has already developed, salvage-type procedures may be considered, such as removal of degenerated bone or partial or complete fusion of the wrist joint.