Treatment of scaphoid pseudarthrosis
A scaphoid fracture that shows no signs of union after 3 – 4 months in plaster will not heal with further conservative treatment, and should be referred for surgery (13). A review of 270 scaphoid pseudarthrosis cases showed that almost half the patients did not go to a doctor when they were injured. Only 53 of the 270 were diagnosed as having an acute scaphoid fracture, while 93 fractures were overlooked by the doctor. X-ray pictures were taken in 60 of these cases. Only 30 scaphoid fractures were cast immobilised and treatment carried out according to plan, but seven of these fractures were displaced and should have been operated upon in the first instance (3). Forty-seven of the 270 patients received were unnecessarily immobilised for 2 – 4 months after they were diagnosed with manifest pseudarthrosis.
Pseudarthrosis with incongruence and displacement causes arthrosis, which starts radially with ulnar and mid-carpal progression. Arthrosis is seen in the majority of patients in the course of 5 – 10 years (30) – (32). With advanced arthrosis involving considerable pain and mobility loss, there is no point in operating upon the pseudarthrosis. Depending on the pain, extent of the arthrosis and functional requirements, these patients should be offered a wrist prosthesis, or alternatively partial/total wrist arthrodesis (33) – (35).
It is generally agreed that scaphoid pseudarthrosis in the middle and distal part without arthrotic changes should be treated surgically with an avascular bone graft from the crista iliaca or distal radius, internal fixation with metal pins or screws (Fig. 5). The surest is to have a cast for 12 weeks post-operatively. The rate of union is 85 – 95 %, patients report little pain and achieve excellent wrist function, but accompanying arthrosis results in reduced function (36) – (38). A lower rate of union has been described for outdated methods, where only bone grafts are used without simultaneous internal fixation (39). Two prospective randomised studies have been conducted of scaphoid pseudarthroses where pedicled vascularised radius bone grafting was compared with non-vascularised crista and radius grafting. The patients in the first study had plaster casts for four weeks, and the healing frequency for avascular bone grafts (73 %) was lower than for vascular bone grafts (89 %), but also lower than in most retrospective studies where patients spent 8 – 12 weeks in casts. The study has not led to a change in the choice of bone graft in connection with pseudarthrosis treatment (40). In the second study, union rates were similar, and the gain offered by vascularised bone grafting was too small to justify the more resource-intensive and technically demanding procedure (41).
There is lack of consensus regarding treatment of the most proximal scaphoid pseudarthroses. Reduced blood circulation, a limited contact surface between the fragments, small fragments that provide little grip for fixation, and strong forces acting over the pseudarthrosis gap, can reduce union. Standard pseudarthrosis surgery as described above is used by many, while some prefer technically demanding vascularised bone grafts from the distal radius. The results vary, and there is no evidence that one method is superior to others. Lack of consensus on the definition of non-vascularisation of the scaphoid (sclerotic proximal fragment on the x-ray, non-vascularised fragment seen on the MRI with contrast, the surgeons’ intraoperative assessment of vascularisation in the fragment) makes it difficult to compare the patient series and the results (37, 42) – (44). The most proximal scaphoid pseudarthroses account for a very small percentage of patients. In our view, these should be referred to specialist hand surgery departments.