The carpal scaphoid bone is a small C-shaped bone located on the radial side or thumb side of the wrist. It is shaped much like a very fat potato chip and helps connect the wrist and thumb. It is in a very critical biomechanical position in the wrist, between two rows of wrist or carpal bones. It is the most frequently broken of all little wrist or carpal bones. The usual mechanism is a fall on the outstretched hand. There are both compressive and tension forces on this bone during a fall. The scaphoid bone may be broken in the mid waist (most common), the distal portion near the thumb or the proximal portion near the mid wrist. See figure 2. scaphoid fractures are also one of the most commonly poorly healing fractures of the wrist. The blood supply to the scaphoid bone is unusual, entering the bone from the thumb or radial side and traveling backwards towards the wrist. A fracture of the scaphoid may disrupt the blood supply to the bone, leaving one half without blood supply. This can result in delayed healing or nonhealing of the fracture. In general healing of the proximal scaphoid fractures are the worst, followed by waist fractures. Distal scaphoid fractures in most cases have relatively good blood supply and heal normally.
Scaphoid fractures are also the most commonly missed wrist bone fracture. Often a patient will believe that they have “sprained her wrist” and treated conservatively. They may do well for years until chronic wrist discomfort appears. X-rays will then reveal a chronic nonunion or nonhealing of the fracture with some collapse of the scaphoid and degenerative changes in the scaphoid as well as wrist arthritis. The natural history of non-treated scaphoid fractures reveals a high rate of nonunion and progressive development of wrist arthritis over a 10 to 15 year. Even if initial medical care is received after a fall, the initial x-rays may appear negative and the fracture undetected until later. A high index of suspicion is sometimes necessary to recognize and treat this injury early.
It is important to completely evaluate the scaphoid fracture pattern and alignment in order to prepare a complete treatment plan. This may involve taking special x-rays, a CT scan or MRI to assess the alignment and blood supply of the scaphoid. the location and orientation of the fracture must be determined. It must also be determined whether the fracture is well aligned and nondisplaced, or flexed and compressed, or apart and separated. Patient factors such as age, general health, smoking and malnutrition are also important factors in scaphoid healing.
Due to the high rate of delayed union or nonunion, treatment of scaphoid fractures remain highly discussed in sometimes controversial. Many research papers have been written and academic discussions and given about the treatment of scaphoid fractures. As a result treatment plans are varied in different areas of the country and among different surgeons. we have taken a moderate but occasionally aggressive approach to scaphoid fracture treatment, based on our extensive experience with treating both acute fractures and chronic fracture nonunion referred to us for treatment by other orthopedic surgeons.
Truly nondisplaced scaphoid fractures confirmed by CT scan and seen right away maybe treated conservatively in young healthy patients especially in the distal scaphoid fractures. A long-arm thumb spica cast above the elbow is usually applied for 6 weeks with a short arm thumb spica cast used afterwards until the fracture is healed. The patient will be started on vitamin D and calcium to help bone healing. An external bone stimulator may also be used to help assist healing. even with direct immediate recognition of the fracture and treatment, nondisplaced fractures sometimes occasionally are. delayed in healing or do not heal. in those cases internal fixation with a screw and placement of bone graft in the fracture site may be required. For athletes or for proximal pole fractures, early percutaneous screw fixation may be selected. A small incision is made over the wrist and a small screw was placed under x-ray guidance across the fracture site to compress it and improve healing percentages. After surgery a short arm thumb spica cast or splint including the thumb is used. Gentle early wrist motion may be initiated earlier due to screw fixation. Although the odds are improved, there are cases of delayed healing or nonhealing with this technique also.
In cases of displaced scaphoid fractures or chronic scaphoid nonunions, open reduction and internal fixation(ORIF) may be utilized. in this surgery and incision is made on the palmar side or dorsal side(back) of the wrist over the fracture. the fracture alignment is corrected (reduced). In cases of chronic nonunion, in area of cystic degeneration or fiber scar tissue may exist at the fracture site and require removal. If a gap exists after reducing the fracture, that space is filled with bone graft , usually taken from the adjacent radius. A compressive screw is then placed across the fracture under x-ray guidance and the fracture is stabilized. The soft tissue was then closed in a protective thumb spica splint or cast applied. once again vitamin D and calcium and an external bone stimulator may be used to help healing. and cases of chronic scaphoid nonunion where arthritis of the wrist has already developed, another procedure such as removal of the scaphoid and proximal row carpectomy or wrist fusion may be required for treatment. The general risks with treatment of scaphoid fractures are anesthesia the risks, wound healing problems or infection, delayed healing or nonhealing of the fracture, as well as wrist arthritis. Sometimes despite our best and most aggressive treatment the fracture simply does not heal