The scaphoid is a bone with a bad reputation. And with a number of good reasons:
1. scaphoid fractures can be difficult to diagnose
because of its orientation in the wrist, scaphoid fractures are not always visible on plain X-rays. This can lead to uncertainty in the Emergency Department, and frustration for the patient who wants to know whether they have a fracture or not.
2. scaphoid fractures can be slow to heal or not heal at all
the scaphoid is a small bone, almost entirely covered by cartilage with a blood supply dependent on a few small arteries. An unstable fracture can lead to a degree of motion through the fracture, joint fluid runs through the fracture, the cells lack normal blood supply and hey presto, a scaphoid “non-union”. This is where the bone ends at the fracture resorb, and the fracture is replaced by fibrous tissue. Just to make things worse, sometimes one end of the scaphoid, affected by the lack of blood supply, can collapse. Even patients who are lucky enough to have their scaphoid fractures heal can be very frustrated while they wait. Sometimes scaphoids heal very slowly.
3. scaphoid fracture healing can be difficult to determine
again, plain X-rays may give the impression that the scaphoid has healed, when in fact it hasn’t. Quite frequently I see patients who are sent with a “re-fracture” from minimal trauma. What they have is not a “re-fracture” but a non-union. The fracture didn’t heal properly after the initial injury, the mistake was believing the x-ray which didn’t show the line of the non-union. Although x-rays are helpful when done properly, CT scans are necessary to show the details of scaphoid healing.
4. scaphoid non-unions can lead to wrist arthritis
if the scaphoid collapses through the non-union, it leads to a “humpback” deformity. This shortens the scaphoid, and creates abnormal loads through the wrist which can lead to a predictable pattern of wrist arthritis (SNAC wrist or scaphoid non-union advanced collapse).
So what do I recommend for patients with a possible scaphoid fracture?
- early accurate diagnosis – if the wrist is swollen after an injury and the x-rays are normal, an MRI scan will help define a scaphoid fracture. If there is a fracture line on MRI, sometimes a CT scan will help provide additional information about the bony detail.
- consideration of minimally invasive surgical stabilisation – it is fairly clear that stabilising a scaphoid fracture will improve the rate of bone healing. Previously open surgery was required to insert a screw. This introduced the concern of making the blood supply worse, by releasing the soft tissue attachments. These days, improved equipment means that a screw can be accurately inserted through a 5mm incision. In the operating theatre, fluoroscopy (live X-ray) control is used to position a smooth pin in the centre of the scaphoid. In addition to fluoroscopy, I use arthroscopy to help reduce the joint surface and to ensure there is no penetration of the joint surface by the pin or screw. Arthroscopy is the gold standard in this regard. The pin position is adjusted if necessary, then a cannulated screw is inserted over the pin, which is then removed. Everything is finally checked under arthroscopic control. The tiny wounds are sutured.Wrist motion can begin the next day, as a cast is no longer necessary to support the bone. Some surgeons and institutions recommend cast treatment for those scaphoid fractures deemed to be stable. This is in no way unreasonable, since the minimally invasive surgery is fairly technical and equipment intensive, making it significantly more expensive than cast treatment. However, for an individual who wishes to maximise both early recovery and the chance of healing, I would recommend surgical stabilisation.
- following healing with CT scan – this would usually be at 8 weeks. If there are signs of bone crossing 60% of the fracture line, I allow the patients to return to all activities, including loading as able. Once healing has occurred, the risk of later arthritis should revert to normal