Scaphoid nonunion can be stable where fibrous union is present or it could be unstable.
In patients where the fracture has not shown any union even after 12 weeks of immobilization, option of surgery should be discussed with the patient. If patient wants a further trial of non operative treatment, another cast can be applied for 4 weeks.
A fracture not uniting after 16 weeks should be considered for surgery. The surgery consists of opening the fracture, removal of fibrous tissue, fixation with a compression screw and bone grafting.
Scaphoid nonunion can be of two types stable (Herbert Type D1) and unstable non union (Herbert Type D2) of scaphoid.
Stable Scaphoid Nonunion (Herbert Type D1)
Stable nonunion of scaphoid is characterized by a firm fibrous nonunion that prevents deformity from occurring. The dimensions and shape of the scaphoid remain well preserved and there is minimal risk of secondary arthritis.
Xray of these cases would show a fracture line with variable cystic changes affecting the bone fragments. The patient in this kind of nonunion have minimal symptoms.
The problem in these cases occur in case of secondary trauma which converts a stable nonunion to unstable nonunion.
The patient with stable scaphoid nonunion should be encouraged to get treated in spite being symptom free as fixation of stable nonunions give better results than unstable nonunions. [ And there is a risk of becoming a stable union an unstable union with additional trauma.]
An early treatment further reduces the incidence of secondary osteoarthritis. Percutaneous screw fixation provides good results.
Unstable Scaphoid Nonunion (Herbert Type D2)
Sclerosis of bone surfaces, synovial erosion, fibrous cysts indicate an unstable nonunion.
Unstable scaphoid nonunion leads to decrease in fragment size, collapse and deformity.
Unlike stable unions, which give good results, the results of treatment of fractures the result depends on the viability of the fragments and the extent of secondary changes.
The treatment includes
- Complete resection of the nonunion
- Correction of deformity
- Bone graft
- Screw fixation
Time between the initial fracture and treatment of the nonunion and the presence of osteonecrosis are important determinants of prognosis.
MRI can be used preoperatively for assessing presence of osteonecrosis.
Other Procedures For Scaphoid Nonunion
Partial or complete excision of scaphoid
A very small fragment can be excised but if it is more than 8 mm long, the results are poor and wrist weakness would result
Wrist denervation can result in significant pain relief.
Proximal Row Carpectomy
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