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Possibility of surgical treatment of long bone shaft fracture in children with the use of POLFIX external fixator is presented. The method was employed in 17 cases treated in Children Surgery Department between 1993 and 1994. Early mobilization was possible and the treatment duration has been shortened.
During the past decade the useful classification and principles of management of the fractured pelvis have progressed rapidly. For the acute management the principal consideration is the control of severe intrapelvic hemorrhage. A protocol has been developed that combines the early application of external fixation with a closed reduction of the pelvic fracture. A marked decrease in the anticipated amount of intrapelvic hemorrhage has been documented. The coupled double anterior frame and its biomechanical equivalent, the newly developed triangular system, are easily applied to the pelvic ring and provide adequate stability for the treatment of the patient with a stable or unstable pelvic ring fracture. Thus the complex earlier design has been replaced by a simpler system. The triangular frame provides adequate stability so that the patient can undertake independent bed-to-chair transfers and early resumption of a weight-bearing gait. Late pulmonary, gastrointestinal, and urologic complications with prolonged bed rest and cast immobilization therefore have greatly diminished. In the present series in which external fixation has been applied to unstable pelvic ring fractures with a single posterior disruption, late loss of reduction, nonunion, and malunion almost have been entirely avoided. In addition, a simple triangular frame provides access to the abdominal wall and offers minimal postoperative interference with nursing care of the patient. Once the general condition of the patient has stabilized, supplementary techniques of open reduction and internal fixation may be applied to appropriate complex fracture patterns. These methods are fully reviewed elsewhere. Thus early rigid stabilization of the patient who sustains a pelvic ring fracture facilitates diminution of fracture pain, early mobilization of the patient, discharge, improved morale, and ultimately, decreased fracture morbidity and mortality.
This study demonstrates that the clamped-wire system used to suspend bones within an Ilizarov external fixator yields when the perpendicular load exceeds 50 N per wire. Cyclic loading was applied to tensioned wires clamped within an Ilizarov ring component, with steadily increasing load amplitude. Wires were tested at four initial tension settings. The amount of energy lost within the clamped-wire system per load cycle was calculated for every test. The results showed that there was a consistent trend to increasing non-recoverable energy loss per load cycle when peak loads exceed 50 N for all initial tension settings. A finite element (FE) model replicating the experimental conditions was performed to investigate the levels of stress within the loaded wires. The FE model analyses showed that high stresses were generated in the wires close to the clamping sites, and that the stress levels could reasonably be expected to exceed the material yield stress when loaded to about 55 N, for all initial tension settings. The results show that material yield, accompanied by some wire slippage through the clamps, is responsible for system yield, in agreement with previous studies. Although the initial wire tension has an appreciable effect on the wire stiffness, it did not affect the elastic load range of the clamped-wire system. To prevent yield of the clamped-wire system in practice, the fixator should be assembled with sufficient wires to ensure that the load transmitted to each wire by the patient does not exceed 50 N.
Static and fatigue tests of the standard Orthofix unilateral external fixator (Orthofix SRL, Verona, Italy) were performed. Under similar fixation configurations, the Orthofix device offered higher bending stiffness in both directions, equal torsional stiffness, and lower axial stiffness when compared to the Hoffmann-Vidal quadrilateral frame with full pins. The bending resistance of the Orthofix ball joint was found to be proportional to its locking cam tightening torque. After applying 2 million loading cycles to the bone ends fixed by the device, the overall stiffness characteristics of the frame did not change significantly. Repetitive manual tightening and loosening of the ball joint caused abrasive wear on the cam and bushing surfaces. The locking position of the cam migrated for a mean of 45 degrees. After 50 cycles of tightening and bending to failure, the ball joint locking strength was reduced by 20% to 25%, but the stiffness did not change. Wear and stripping of the seat of the fixator body locking screw and the pin fixation screw threads were also noted. Based on the test results, the standard Orthofix device could be re-used, but certain fixator components must be inspected and replaced. The ball joint locking cam and fixation screws required periodic tightening during clinical application to prevent loss of frame stiffness under repetitive loading. Modifications of the fixator design are recommended to improve its mechanical performance.
We conducted a small retrospective study of rates of early complications associated with external fixation of pediatric femur fractures and compared rates at our institution with those reported in the literature. In our series of 22 patients, early complications included 12 pin-track infections (54.5%), 2 cases of loss of reduction (9.1%), 1 pin-track abscess (4.5%), and 1 refracture (4.5%). Overall rates (ours combined with those reported by other investigators) were 4.7% (34/719) for refractures and 33.1% (224/677) for pin-track infections. Factors that correlated with refractures were open fracture, bilateral fracture, and longer time in fixator. Factors with inconclusive correlations were fracture pattern, dynamization status, fixator type, pin size, and number of pins.
Static and fatigue tests of the small Orthofix unilateral external fixator frame and its main components were performed. The use of six pins increased torsional rigidity, but this configuration failed at lower bending loads when compared to the four-pin configuration, reflecting the uneven holding strength of the pin clamp on three pins. The ball joint maximum torsional resistance was reduced by 27.2%, and the maximum bending resistance was decreased by 35.2% after first failure loading of a fatigue test. The strength of the ball joint returned to the normal level after replacement of the cam and bushing with new components. The locking strength of the fixator body telescoping mechanism was high and did not change during repetitive failure loading. Hence, the fixator should be applied under the four-pin configuration, placing pins in the outer slots of the clamps as recommended by the manufacturer. The frame stability is governed by the performance of the ball joint, and its locking cam should be tightened periodically. If the ball joint locking position starts to migrate from its initial position, the cam and bushing should be replaced.
We present a technique for the external fixation of femoral derotation osteotomy performed as part of the management of patients who present with developmental dysplasia of the hip. The technique was used following open (25 hips) or closed (31 hips) reduction and clinical and radiologic review was undertaken between 5 and 18 years (mean 11 years) after the procedure. Eighty-four percent of the patients (43 patients, 47 hips) were found to have a Severin clinical grading of 1 or 2 and over 70% were grade 1 or 2 radiologically. Nine hips/patients had required further surgery following the reduction (open or closed) and osteotomy. The complications of the procedure are described; whilst some of these are clearly associated with the osteotomy it is probable that others, such as avascular necrosis, are attributable to the method of reduction. The overall results are thought to stand up well to comparison with other series, suggesting that the technique has no major disadvantage, apart from being unable to control the pins and pin holes and to detect discharge and infection underneath the spica, which did not seem to be a problem in our study. It is suggested that the main advantages are: (1) a lower risk of damage to the trochanteric growth cartilage in comparison with other fixation techniques, because soft tissue dissection is less extensive and the implant is already removed after 6 weeks; (2) a greater accuracy with regard to the derotation angle; and (3) the avoidance of a further open procedure to remove the implant, which can be difficult with plates if the removal is postponed for too long.
A technique of radius opening-wedge osteotomy, bone graft, and external fixation for the treatment of symptomatic radius malunion is presented. It provides direct rigid fixation to the osteotomy components, thus maintaining the correction while allowing early wrist exercises. This technique has been effective for 7 patients in correcting deformities that averaged--20 degrees palmar tilt with radial shortening of 3.4 mm to a postoperative average palmar tilt of 5.3 degrees and -0.4 mm radial shortening. It is an alternative technique for the hand surgeon treating radius malunion and can be easily combined with adjunctive procedures.
The success of the Ilizarov technique is due to the combination of the biomechanics of its external fixator and the biology of distraction osteogenesis. The stability and stiffness of the conventional Ilizarov fixator is attributed to its use of a K-wire cross structure. The disadvantages of this structure include pain, and possible neurologic and vascular injuries when the wires are introduced into crucial neurovascular areas, as well as increased frame complexity and construction. Reducing the number of wires decreases these problems, but also decreases the stiffness of the system. Hybrid (wire and half-pins) Ilizarov fixators and half-pin fixators are also being used in an attempt to alleviate these problems. Half-pins have been described by Fleming et al. and Green as causing minimal transfixation of the surrounding soft tissues and capable of and being inserted into anatomically safe areas. The stiffnesses of the hybrid systems have not been measured. This study reports on the stiffness of different wire and half-pin systems that were biomechanically tested in axial loading, anterior-posterior bending, medial-lateral bending, and torsional loading. The results demonstrated that the conventional Ilizarov fixator with wires possesses a high axial stiffness, whereas the fixator with half-pins possesses higher stiffness under bending and torsional loads. To obtain adequate stability, the use of hybrid Ilizarov frames with one wire and two or more half-pins (5 or 6 mm in diameter), or larger half-pin frames (5 or 6 mm) with three pins is recommended.
In a prospective study, we investigated the effects of external fixation on fracture union in skeletally immature patients. Twenty-five fractures of the femur and tibia in 21 patients were fixed externally with the intention of leaving the fixator in place until the fractures consolidated or nonunion was established. The main indications were head injury and multiple trauma. One hundred percent of the fractures consolidated with the fixator in place; 45 of 50 joints had 100% motion, three had 95% motion, and two had 60% motion owing to scarring from traumatic wounds. Eight-four percent of the fractures lost no position in the fixator, and 16% lost < or = 5 degrees.
In 11 patients with a Rolando's fracture of the first metacarpal, the mini-Hoffman external fixation was used to maintain closed reduction of the fracture, with two pins placed distally in the first metacarpal and one pin proximally in the trapezium. The results were excellent in 7 patients; in 3 patients mild arthritis was noted radiographically, and one patient had a poor result because of severe postraumatic arthritis 1-5 years (mean 30 months) after the injury. This method of treatment is proposed for patients with Rolando's fracture as it is very easily performed and provides good results.
Intraarticular phalangeal fractures are difficult to treat. The advantages of using dynamic external fixation devices include distraction of impacted fracture fragments and reduction in joint stiffness by allowing early joint mobilization. Previous reports have concentrated on pilon fractures and dorsal fracture dislocations affecting the proximal interphalangeal joint. We report our experience using a dynamic external spring fixator in the management of 15 patients with a variety of fracture patterns affecting the metacarpophalangeal, proximal interphalangeal and distal interphalangeal joints. In three cases the device spanned two adjacent joints. Long-term follow-up has shown excellent range of joint movement and no major complications. We consider that this device is an effective tool in the management of a range on complex intraarticular phalangeal fractures.
The conversion method from external fixation (EF) to intramedullary nailing (IMN) for open tibia fractures, especially to Gustilo type IIIB open tibia fractures, have potentially high risk of infections. We document a report of a more progressive approach in four consecutive cases of type IIIB open tibial fractures successfully managed with early unreamed IMN without a safety interval and simultaneous flap coverage following EF. The mean patients age at the time of injury was 43.8 years (range 23-64 years), and three patients were male. The timing from EF to IMN without safety interval combined with well-vascularised flap (free latissimus dorsi flaps in two patients and pedicled soleus flaps in two patients) ranged 48 to 72 hours. Average time to union was 14 months (range 9-21 months). There was one nonunion patient whose fracture healing was gained by reamed IMN without bone grafting. However, there were no infections. The functions in all patients were satisfactory. This early unreamed IMN without a safety interval and with simultaneous flap coverage following EF is a useful and effective option for treating type IIIB open tibial fractures.
Eleven patients with an isolated and displaced tibial fracture were treated by external fixation with a simple device to provide mobile traction. Anatomical results were good and all fractures healed uneventfully with minimal morbidity.
This prospective study describes the experience with a new dynamic external fixator which provides three degrees of freedom, while the centre of rotation of all these movements is located in the wrist. 44 patients with unstable fractures of the distal radius were included. During the period of dynamisation, with a median flexion of 30 degrees, extension of 18 degrees, radial deviation of 0 degree and ulnar deviation of 20 degrees the range of motion needed to perform activities of daily living was approached. In spite of early mobilisation reduction was maintained. The radiological result was excellent or good in 82% of the patients and the functional result was excellent or good in 92% of the cases. Pin track infections were noted rather frequently, possibly related to the interaction between the soft tissues and the fixator pins. Based on the experiences of the study the device needs further improvement.
This paper describes the use of acrylic resin instead of a Kirschner clamp for treating bone fractures. The technique is cheaper than using Kirschner external skeletal fixator and allows greater flexibility for pin placement. It is also less prone to self mutilation by dogs than the entirely acrylic external fixator. The modified acrylic fixator gave results similar to those obtained with the Kirschner external fixator, when used in 54 dogs and 28 cats.
In five patients with ipsilateral femoral and tibial shaft fractures the Hoffmann apparatus was used to stabilize the fractures of both the femur and tibia. The patients walked early and there were no disturbances of fracture healing. The pin track became infected in three patients. It is suggested that in patients with ipsilateral fractures of the femur and tibia external fixation is indicated for the tibia and that the fracture of the femur should be stabilized by closed medullary nailing. If the patient is critically ill or if there is gross comminution of the femur external fixation is indicated for this fracture as well.
BACKGROUND: Maintenance of wire pretension in an Ilizarov external fixator is dependent on the torque applied to the fixation bolts. We therefore measured immediately after surgery the clinically applied torques. The median value was only 10 N m (range 8-14N m). We wondered whether this value is appropriate to maintain the wire pretension and thereby to achieve sufficient fracture stability during dynamic loading of the device for a longer period. METHODS: A material testing machine dynamically loaded one wire mounted on one ring. Several configurations were tested. RESULTS: A quick decrease in wire tension to a steady state situation was seen. In the most stable configuration (20 N m wire fixation torque) 50% of the initial 90 kg wire pretension remained after dynamic loading with 200 N. In the least stable configuration (10 N m torque) considerable wire slippage occurred even without loading and no tension remained after loading! No plastic deformation of the wires was observed so loss of wire tension was due to slippage of the wires through the fixation bolts. INTERPRETATION: With the small fixation torques used in clinical practice considerable wire tension is lost even after a few loading cycles. Further research should address the question whether preservation of a higher wire tension during long term loading promotes faster fracture healing.