80 per cent of axial loads at the wrist are supported by the distal end of the radius and 20 percent by the triangular fibrocartilage and the distal end of the ulna. The limitation of external fixation to achieve articular congruity in the comminuted intra-articular fractures of the distal radius has been documented previously. This could be because external fixation alone does not expand crushed cancellous bone and cannot work without soft tissue hinges .
Skeletal traction maintained by a half frame external fixator between the radius and second metacarpal bone appears to provide appropriate stabilization of the fragments. External fixator provides stability and fixed traction, prevents shortening due to either bone loss or late resorption of cancellous bone from the metaphysis. A study by Sommerkamp et. al stated that the loss of four millimeters of radial length in the dynamic-fixator group over the course of treatment was significantly greater than the one-millimeter loss in the static-fixator group .
Current concepts reflect the growing popularity of external fixation of complex distal radius fractures because it provides easy accessibility of wound care and it can be combined with secondary procedures like bone grafting and skin coverage.
Age and sex incidence
Age group ranged from 20 yrs to 58 yrs with mean of 38. 47 yrs. Increased incidence of these fractures in males(88. 46%) in our series (Cooneyet. al 11. 6%) especially in adults is attributed to high level of activity in males and road traffic accidents(84. 61%) among riders of two wheelers.
Type of fracture/Classification
Majority of fractures were closed(94. 23%). All fractures were of Type IV Universal classification 2 Type IV A, 31 Type IV B, 19Type IV C.
Timing of fixator removal
Recommended duration of external fixation use varies and sometimes extends to between 8 and 12 weeks . Until fixator removal, patients were followed up once a week. Average duration for removal was 8 weeks indicated by radiological fracture union which was the main criteria. In literature the duration of use of fixator ranges from 8 to 12 weeks. Fair and Poor functional results can be attributed to extended period of application of external fixation in 4 patients.
Bone grafting is the mainstay of treatment in any distal radius fractures with large metaphyseal void which are prone to collapse at later date. Cancellous bone grafts harvested from the iliac bone reduced the period of external fixation and supported the articular surface. Packing cancellous bone chips into these comminuted fractures increased the rigidity of reduction fourfold . Bone grafting was carried out either primarily or secondarily and also on the acceptability of patients for bone grafting. Bone grafting improved the anatomical alignment of the fragments and the articular congruity and allowed early mobilization of the wrist and fingers. The external fixation does not provide the absolute stability to maintain the comminuted intrarticular fractures. It takes a longer time for the fracture gap to be filled by new bone formation. In study of Overggard et. al over a seven-year follow-up, seventeen (30 per cent) of their fifty-six patients had radiographic evidence of osteophytes and eight patients (14 per cent) had advanced radiographic changes . In our study late collapse was not noticed in patients who underwent bone grafting after 7 year followups. By pushing the grafts towards the distal articular surface many of the die punch fragments which cannot be reduced by ligamentotaxis alone can be adequately lifted, reduced and supported to achieve congruent articular surface . Bone grafts supply an interosseous distension force which enhances the ligamentotaxis and helps to line up the juxtaarticular bone fragments to maintain the integrity of the distal radius.
Combination of ligamentotaxis and cancellous bone grafting produced excellent clinical and radiological results. As Green pointed out good functional results usually follow good anatomical results. Our method utilized both biological and mechanical effects of bone grafting enabling us to reduce the duration of external fixation and to obtain internal trabecular healing. Tight packing with bone grafts produces better load bearing, fills space and stretches and tightens the residual periosteum. Then compressive strength of bone tissue is proportional to the square of the apparent density. So highly compact cancellous bone grafts provides good stability in metaphyseal fractures.
We believe that it is the quality of reduction that determines the clinical outcome. Thus the aim of external fixation is to obtain and maintain an accurate anatomic reduction of the fracture fragments and to prevent collapse, malunion, deformity and late osteoarthritis. Maintenance of radial length results in good functional outcome. The average radial height in AP view is 11 to 14 mm and a height of less than 4 mm corresponds to poor Haddad et. al in his study of 43 patients showed that all but two of the patients (5%) had a volar tilt of up to 16°, the radial length was restored in 77% and excessively shortened by 3-4 mm in 9 patients (23%) . Leung et. al in his series showed loss of radial articular angle (mean 2. 2 degrees) after removal of the external fixator. In our series in 95% of cases, radial length of more than 6 mm was maintained. Decrease in the excellent functional results with respect to the maintenance of radial length of more than 6 mm is due to the non cooperation of patients for physiotherapy and longer periods of immobilisation. In our series restoration of the normal volar tilt in 90% of cases resulted in excellent anatomical result. The excessive dorsal tilt produces a dinner fork deformity and decreases the range of palmar flexion and also causes midcarpal instability due to changes in load distribution. The collapse of the articular surface was not encountered in the dorsal angulations in our series as the patients were not allowed to perform extension for an additional 2 weeks after external fixator removal.
Range of movements
Most patients regained good range of motion of wrist and forearm all obtained normal finger movements. Inspite of satisfactory reduction in 2 cases, persistent wrist stiffness was encountered. This limitation of joint motion is well tolerated by patients as the majority of hand tasks can be accomplished with 70% of maximal range of wrist movements which is revealed in this study. For routine functional activities we require 35 degree of dorsiflexion and 10 degree of palmar flexion of the wrist has been achieved in all the cases in the study. No other method appears to be technically simple and to give such excellent results.
Posteromedial fragments, Indirect control of fragments, No accurate reduction of intraarticular fragments, Excessive distraction. Reduction and maintenance of reduction is more difficult using bridging external fixation because there is indirect control of the distal fragment, which depends on ligamentotaxis; this may not be successful in restoring the volar tilt or the radial length . Difficulty in achieving volar tilt also may be due to the fact that the stout palmar radiocarpal ligaments reach maximum length before the z-shape dorsal ligaments, preventing the latter from pulling the dorsal aspect of the distal end of the radius into its normal palmar inclination. Considerable transfer of load onto the ulna occurs with progressive dorsal angulation of the distal end of the radius .
Tissue perforation (n = 2), Pin tract infection (n = 2), Pin loosening (n = 3), bending and breaking of pins(n = 3), Loss of reduction(n = 3), Stress fractures(n = 2), Inflammatory reactions(n = 4), Osteolysis of cortices(n = 3), Spontaneous pullout of pins(n = 2), Neuroma of sensory branch of radial nerve(n = 2), Reflex sympathetic dystrophy (n = 3), Wrist stiffness (n = 3), Rupture of EPL tendon(n = 1), Osteoarthritis of wrist(n = 2).
Loss of reduction was seen in 3 patients only that confirms to previous studies, which show that external fixation effectively maintains the reduced position .
Restriction of movements at the wrist has been attributed to the extended period of application of external fixation and improper physiotherapy and also due to associated injuries in the ipsilateral limb which interfered with the physiotherapy. Use of open pin insertion technique with a predrilled system has reduced the injury to both tendon and nerves. Radial sensor nerve is generally not at risk when pins are placed 10 cm proximal to the radial styloid process by this technique. Open pin placement and pin insertion with sharp drill bits and improved fixation with better thread design and insertion of pins at an angle of 60 degrees to each other increased the purchase of pins in the bone and decreased complications like pin bending, loosening and breakage. Papadonikolakis et. al in their study concluded that more than 5 mm of wrist istraction increases the load required for the flexor digitorum superficialis to generate MCP joint flexion for the middle, ring, and small fingers. For the index finger, however, as much as 2 mm of wrist distraction significantly increases the load required for flexion at the MCP joint.
Complex distal radius fractures pose a significant challenge to the practicing surgeon because of the inherent tendency to collapse resulting in malunion, deformity. loss of function and late osteoarthritis. Fair and poor results were attributed to associated injuries and extended period of application of external fixator. Lunate fragments which could not be reduced by external fixation required open reduction, fixation with K wires and bone grafting. Ulnar styloid process fractures were not actively treated in this study. Late collapse of the articular surface led to early arthritis. Bone grafting should be performed to obtain good articular congruity and to prevent deformity. Although AO external fixator provides absolute rigidity and stability, restoration of original palmar tilt could not be achieved in all cases despite maintaining radial length and radial. The restoration of palmar tilt requires multiplanar ligamentotaxis or a pin in the dorsal fragment. Majority regained more than 63 percent of grip strength. It is decreased in patients with increased radial tilt, associated injuries and prolonged immobilisation. The final outcome of functional results in complex distal radius fractures depends on patient selection, fracture morphology, obtaining accurate reduction and maintaining it by external or internal fixation, bone grafting inpatients with large metaphyseal void, patients compliance towards physiotherapy and associated injuries.