Scaphoid Fracture

 

The scaphoid bone is one of eight 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 spans the two rows putting it at extra risk during injury, which accounts for it being the most commonly fractured carpal bone by far.




Fracture of the scaphoid bone occurs most frequently from a fall onto the outstretched hand where the wrist is cocked up forcefully. Typically there is pain initially, but the pain may decrease after days or weeks.  Bruising is rare, and swelling may be minimal. Many people with this injury mistakenly assume that they have just sprained their wrist, which can lead leading to a delay in seeking evaluation


Scaphoid fractures are most commonly diagnosed by x-rays of the wrist.  However, when the fracture is not displaced, x-rays taken within the first week may not be easily reveal the fracture. A non-displaced scaphoid fracture could thus be incorrectly diagnosed as a sprain because the x-ray was negative. 


To err on the side of safety, a patient who has significant tenderness directly over the scaphoid bone (in the snuffbox) should be suspected of having a scaphoid fracture and be splinted either in plaster or a futura type splint and activities restricted. 


About two weeks later the patient should be re-evaluated, and if findings are still suspicious for a scaphoid fracture, x-rays at that time will usually show the fracture due to changes in the bone at the edge of the fracture. 


In cases where waiting two weeks in a splint may cause undue hardship, or if the x-rays remain negative but the clinical exam is still suspicious, more sophisticated (and expensive) imaging techniques may be utilised, such as CT scan, bone scan, or MRI.



Treatment


If the fracture is non-displaced, it can reasonably be treated by immobilisation in a cast.  The cast covers the forearm, hand, and usually the thumb, (and sometimes includes the elbow for the first phase of immobilisation).  Although the fracture may heal in as little as 6 weeks, the healing can often be delayed far beyond this period.


There is a variable blood supply to different parts of the scaphoid bone that can be disrupted by the fracture orientation, impairing the 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, accordingly 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 pins are inserted to stabilise the fracture, often with a bone graft to help heal the bone


Sometimes screw fixation surgery is considered even in non-displaced cases so as to avoid prolonged casting as long as the wrist is not loaded excessively during the healing process.


Unfortunately scaphoid fractures are prone to complications.


Non-union: Patients with a scaphoid non-union usually present with a history of previous wrist injury. They will typically have pain along the thumb side of the wrist and may also have reduced range of motion in the wrist, particularly wrist extension. A CT scan is my preferred investigation in planning the approach used for surgery.


Scaphoid fractures may also develop a problem called avascular necrosis. Avascular necrosis occurs when part of the scaphoid dies because of the loss of blood flow. This can eventually result in fragmentation and the collapse of the bone. An MRI scan may be helpful to check for avascular necrosis.


Treatment is dependent upon a variety of factors. Depending upon the stage of this process at which the non-union is recognised, various treatment alternatives exist. In cases without significant arthritis, surgery to restore scaphoid alignment and heal the bone is preferred. This usually requires placement of a bone graft possibly augmented some type of internal bone fixation, such as pins or a screw. Pictures of X-rays showing these can be seen by clicking on this link.


Scaphoid non-unions with avascular necrosis present special challenges to healing since part of the bone is dead. Techniques using bone grafts with an attached vessel to maintain blood supply (vascularised bone grafts) may improve our ability to heal these difficult conditions but the evidence is not clear cut in this respect.


Despite aggressive treatment, a significant number of scaphoid non-unions still fail to heal.


In such cases with established arthritis or failed reconstructive efforts, surgery is tailored towards pain improvement along with maintaining a functional wrist. Depending on the degree of arthritis, surgery may include techniques that spare motion, such as radial styloidectomy (removal of a local piece of arthritic bone), partial fusion of the wrist bones, or proximal row carpectomy (removal of the proximal row of wrist bones).


If the arthritis is more widespread in the wrist, complete wrist fusion may be needed.