The scaphoid is probably the worst bone in the entire arm to break. It has a poor blood supply, it is subjected to high stresses, and it is a very important wrist bone. Scaphoid fractures are serious injuries. Textbooks have been written about them. They love to not heal (i.e. go on to “non-union”) and/or have part of the bone die (“avascular necrosis”: like a heart attack of bone). And if they don’t heal, the wrist almost inevitably develops arthritis.
Scaphoid fractures can be through the waist (middle) of the scaphoid, though its distal third (toward the thumb tip; best chance to heal) or through its proximal pole (away from the thumb tip towards the forearm; worst chance to heal). In adults, if you put a fresh non-displaced (the fragments haven’t moved) fracture into a cast, a distal pole fracture takes 2 months to heal, a waist fracture takes 3 months to heal, and a proximal pole fracture may never heal, and takes 4-6 months to heal when it does. The reason that proximal pole scaphoid fractures often won’t heal in a cast is because these fractures are less stable than the others. Proximal pole fractures will almost always do better with surgical fixation.
Scaphoid fractures often don’t show up on the initial X-rays. Scaphoid fractures may take 2 weeks to become visible on X-ray. And it’s very important not to miss them (see below). The current protocol for an injured wrist with tenderness over the scaphoid is to either place a cast on the wrist for two weeks and then take repeat X-rays or get an MRI. Although it’s more expensive, an MRI can diagnose a scaphoid fracture within 24 hours.
Proximal pole fractures usually require surgical fixation to increase their chance of healing. And because most scaphoid fractures take a long time to heal, in order to avoid 3 months in a cast, most active patients elect to have a screw placed into their scaphoid percutaneously.
Percutaneously means through a very small (1-2 cm) incision. Percutaneous screw placement does not disrupt the soft tissue and blood supply around the scaphoid, which allows it to heal better and quicker than compared to using a traditional open incision. If the scaphoid screw is placed within 4 weeks of the fracture, percutaneous screw placement has a 95% chance of success. After 4 weeks the success rate drops. This 4 week “clock” can be slowed down by casting the wrist, which is why if a scaphoid fracture is suspected, but not proven, a cast is worn until it becomes clear that the scaphoid isn’t fractured. If the scaphoid fracture is diagnosed quickly and fixed percutaneously, most times it heals well with no significant loss of motion or function; it’s almost like the fracture never happened.
Displaced fractures (fractures that have moved) will not heal without surgery, and often require a formal open approach to put the fragments back into position and then fix them. Bone graft from the distal radius, the large bone of the wrist, may also be needed.
Following surgery, if a stable waist fracture is treated within 4 weeks of injury, immobilization can often be discontinued within the first week after surgery. A removable splint is then worn except when showering or doing range of motion exercises. Strenuous use, sports or heavy lifting are not allowed until the fracture has healed. Proximal pole fractures are less stable, and are often casted for 6 weeks, sometimes longer. Every scaphoid fracture is different.
Many times people don’t realize that they’ve broken their scaphoid until many years later. They think they just “sprained” their wrist. These scaphoids go on to a “non-union” (i.e. unhealed situation) that may become temporarily stabilized by scar and become non-painful. Years later the scar can break from minor trauma. These “non-unions” (non-healed fractures) are far more difficult to get to heal and often require surgical fixation through an open incision combined with bone graft taken from the distal radius of the wrist. After surgery, these fractures are often casted for a longer time until they heal. Sometimes the wrist has already developed arthritis from the scaphoid nonunion. Please see the Wrist Arthritis section to see how these are treated.