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PubMed1991

Open tibial fractures. Treatment by uniplanar external fixation and early bone grafting.

Seventy-nine open tibial fractures were treated with unilateral uniplanar tubular external fixators. Excellent stability allowed early weight-bearing. All comminuted fractures, with or without bone loss, and some transverse or short oblique fractures with intermediate fragments were treated by early bone grafting through a posterolateral approach. The external fixator was dynamised as soon as periosteal callus was seen on the radiograph. Bone healing times ranged from 11 to 40 weeks (mean 20). Significant ankle stiffness occurred in 10.9% and leg shortening in 2.8%. Pin track infection was seen in 45.2% but was easily controlled with standard management. The external fixation frame allowed excellent functional freedom for Oriental patients to sit cross-legged and squat. Combined with early bone grafting, external fixation is an excellent method for the management of open tibial fractures.

Adolescent↗
PubMed1999

The biomechanics of hybrid external fixation.

OBJECTIVE: The objective of this study was to ascertain which factors determine the rigidity of a hybrid external fixation frame in a tibial periarticular fracture model. DESIGN: Laboratory investigation using a polyvinylchloride pipe periarticular tibia fracture model. SETTING: Simulated periarticular tibia fractures were created in a tibia model. Instrumented specimens were tested in a biomaterials testing system. INTERVENTION: Groups of simulated periarticular tibia fractures were stabilized with one of nine different external fixation constructs with components from one manufacturer. MAIN OUTCOME MEASUREMENTS: Elastic stiffness was measured for each specimen in compression, torsion, flexion bending, extension bending, and varus and valgus bending. RESULTS: The four-ring Ilizarov fixator was the stiffest in all modes of testing. There was a trend toward increasing stiffness with an increasing number of rings. Fixators constructed with multiple levels of fixation in the periarticular fragment were stiffer in all modes of testing. The additional spacing between wires gained by the use of a single thick carbon ring or the use of a drop wire three centimeters from a single ring did not increase stiffness in this model. Frame modifications intended to augment the bar-to-ring connection did not increase stiffness. The use of rings mounted with half-pins instead of a unilateral bar mounted with half-pins for diaphyseal fixation increased the stiffness of the frame only in torsional testing. CONCLUSIONS: Although the ideal stiffness of an external fixator is unknown, our results show that the addition of more than one level of fixation in the periarticular fragment increases the stiffness of hybrid external fixators in this periarticular tibia fracture model. Augmentation of the ring-to-bar connection did not significantly affect the stiffness of the frame.

Biomechanical Phenomena↗
PubMedDate not supplied

Is external fixation in pediatric femoral fractures a risk factor for refracture?

The aim of this study was to investigate whether external fixation is a risk factor for refracture by comparing the outcomes of children who received three different forms of treatment of femoral fractures. One hundred ninety-two patients treated for femoral fracture between 1990 and 1999 who underwent final examination were assessed. One hundred were treated with hip spica casting after traction, 57 with closed reduction and external fixation, and 35 with open reduction and external fixation. Morbidity results such as time to union, length of hospital stay, refracture, and wire site infection were statistically evaluated. Patients undergoing open reduction had a greater time to union and length of hospital stay and a higher refracture rate. The difference was statistically significant. Wire site infection occurred in all three groups; there was no statistically significant difference between groups. The authors concluded that external fixation is not a risk factor for refracture in the treatment of pediatric closed femoral diaphyseal fractures, and that it may be used with ease in clinics with shortages of personnel and space.

External Fixators↗
PubMed1997

Normal wrist kinematics and the analysis of the effect of various dynamic external fixators for treatment of distal radius fractures.

The purpose of this study was to evaluate the effect that external fixation devices used for distal radius fractures have on normal carpal kinematics, using high speed video data acquisition. Cadaver forearms were stabilized, allowing free excursion of the wrist for passive range of motion. Synergistic muscle tension was simulated by looping the extensor and flexor pairs of the wrist. Global wrist flexion and extension, intercarpal angles, and the instantaneous screw axis (ISA) were studied. These parameters allowed a quantification of normal carpal kinematics and comparison to the kinematics of the carpal bones with external fixators attached. This study shows that normal carpal kinematics during wrist flexion and extension do not have an ISA fixed in or limited to the capitate. In addition, the ISA data provide evidence that translational motion is a real and measurable component of normal carpal motion. This would change the understanding of carpal kinematics in previous studies that suggested that the center of rotation was fixed in the capitate. The proximal carpal (radiolunate) joint contributes more motion (has a greater rotation angle) in normal global wrist flexion and the midcarpal (capitolunate) joint contributes more motion in normal global wrist extension. In addition, the global range of motion and intercarpal joint angle of the wrist are limited with the application of any of the external fixators tested. None of the external fixators allowed normal ISA vector surfaces during wrist motion.

Adult↗
PubMed1994

Combination of the small external fixator and standard tubular system.

A modification of the standard setup of the small external fixator is presented for use mainly on the wrist. The setup used since 1988 offers further possibilities as compared with conventional application: Completely free positioning of the wrist joint for all possible six degrees of freedom, therefore: Better possibility to postpone manual reduction until the frame is applied ("modular" fixator frame, comparable to the tube-to-tube configuration of the standard external fixator), Easy correction of axial, flexural and rotational malalignment during surgery with the external fixator in situ and without changing the pin position, Easy relaxation of overdistraction postoperatively, Temporary postoperative mobilization of the wrist joint possible. Better preoperative distraction due to higher force and longer distance of the compression/distraction device. Rigid construction by using comparably short threaded K-wires and large diameter connecting bar. Less interference with peri- and postoperative imaging techniques.

Equipment Design↗
PubMed1988

Treatment of open tibial-shaft fractures. External fixation and secondary intramedullary nailing.

Between 1979 and 1986, sixteen of 369 open fractures of the tibial shaft were treated by external fixation followed by intramedullary nailing. These fractures comprised one Type-I, two Type-II, and thirteen Type-III injuries. This method of treatment was the original treatment plan in nine patients (56 per cent), for delayed union while the external fixator was still in place in four patients (25 per cent), for loss of reduction in a plaster cast in two patients (13 per cent), and for osteomyelitis and a segmental defect in one patient (6 per cent). The average duration of external fixation was 8.5 weeks; the average time between removal of the external fixator and intramedullary nailing, three weeks; and the average time between injury and nailing, twelve weeks. All sixteen patients were followed until either the fracture had united (eleven patients) or there was an established non-union (five patients). At that time, seventeen additional procedures were performed, including bone-grafting, fibulectomy, and re-nailing. Only five of the sixteen fractures healed without additional surgical procedures or major complications. The five fractures that progressed to a non-union were all Type III, and all were complicated by a deep infection. Over-all, the complications included seven deep infections (an intramedullary infection in four patients, osteomyelitis in two, and a chronic draining sinus associated with a ring sequestrum in one); five minor infections during external fixation, which developed into five of the seven deep infections that occurred after the secondary intramedullary nailing; and eight non-unions, three of which progressed to union after multiple procedures. The over-all incidence of non-union was 50 per cent and that of deep infection, 44 per cent. On the basis of the high incidence of complications in both the present series and the few reports in the literature, we concluded that alternative treatment options should be carefully considered before electing this sequential method of fixation.

Adolescent↗
PubMed1986

External fixation of femoral shaft fractures in spinal cord injury patients.

External fixation was used to treat femoral shaft fractures in nine spinal cord injury (SCI) patients. One patient died of unrelated causes during fracture treatment. Of the remaining eight patients, seven healed their fractures. Two complications, one superficial pin-track drainage and one fracture comminution, occurred in the nine patients. Neither complication adversely affected the patient's final result. In patients with acute spinal cord injury, external fixation should be considered for the treatment of closed femoral shaft fractures with marked comminution, and for open femoral shaft fractures with significant contamination or soft tissue loss. In the chronic SCI patient, external fixation of a femoral shaft fracture may increase the patient's level of independence and mobility during fracture healing, and may permit a more rapid return to the patient's pre-fracture functional level.

Adult↗
PubMed1992

Biomechanical consequences of callus development in Hoffmann, Wagner, Orthofix and Ilizarov external fixators.

A theoretical analysis by a finite elements model (FEM) of some external fixators (Hoffmann, Wagner, Orthofix and Ilizarov) was carried out. This study considered a logarithmic progress of callus elastic characteristics. A standard configuration of each fixator was defined where design and application characteristics were modified. A comparison among standard configurations and influence of every variation was made with regard to displacement and load transmission at the fracture site. An experimental evaluation of standard configurations was performed with a testing machine. After experimental validation of the theoretical model was achieved, an application of physiological loads which act on a fractured limb during normal gait was analysed. A minimal contribution from an external fixator to the total rigidity of the bone-callus-fixator system was assessed when a callus showing minimum elastic characteristics had just been established. Insufficient rigidity from the fixation devices to assure an adequate immobilization during the early stages of fracture healing was verified. However, regardless of the external fixator, callus development was the overriding element for the rigidity of the fixator-bone system.

Biomechanical Phenomena↗
PubMedDate not supplied

[Mechanical study of stiffness in LIM-41 external fixator assemblages submitted to torsion strain].

The mechanical stiffness of LIM-41 external fixator assemlages submitted to torsional strain was studied. A condition of unstable fracture was reproduced. The authors evaluated the effect of of Schanz pin configurations, defined as "distal", "standard" and "proximal", and of the distance, 20 mm, 40 mm or 60 mm between the external fixator and the element employed to simulate bone. The authors conclude that stiffer LIM-41 assemblages are obtained if the "standard" or "proximal" configurations are employed, on which some pins are placed near the fracture simulation site, and if the external fixator body is fitted closer to the bone simulating element, having the former variable greater influence over the stiffness coefficient.

Biomechanical Phenomena↗
PubMed2005

Femoral lengthening over an intramedullary nail using the external fixator: risk of infection and knee problems in 22 patients with a follow-up of 2 years or more.

BACKGROUND: The time for femoral lengthening is shortened if external fixation is combined with intramedullary nailing. However, several complications have been reported with this procedure. PATIENTS AND METHODS: We retrospectively reviewed the outcome of femoral lengthening performed over an intramedullary nail using external fixation in 22 patients. These patients were followed for a mean of 3.2 (2-5.2) years. The mean age was 22 (13-35) years at the time of the index procedure. The mean lengthening was 5 (2.7-8.1) cm and the external fixator was removed after median 20 (8-30) weeks. The mean external fixation index was 24 (11-35) days/cm and the mean consolidation index was 43 (26-55) days/cm of lengthening. RESULTS: 3 patients who had a past history of infection or open trauma developed osteomyelitis which required removal of the nail. There were 4 knee joint complications when the lengthening was over 20%, including posterior knee subluxation and patella subluxation. In 1 patient, the lengthened segment collapsed with breakage of locking screws. INTERPRETATION: Although lengthening over a nail can reduce the duration of external fixation, caution is required to prevent major complications.

Adolescent↗
PubMed1993

Biomechanics and biology of fracture repair under external fixation.

The major factors determining the mechanical milieu of a healing fracture under external fixation, and thereby the mechanism of union, are the rigidity of the selected fixation device, the fracture configuration, the accuracy of fracture reduction, and the amount of physiologic stresses dictated by functional activity and loading. Bone healing problems encountered in fractures stabilized externally merely reflect the severity of the local soft-tissue and periosteal injury and should not be attributed to the inherent features of the fixation modality. Although some surgeons have had reservations concerning the use of external fixation for fracture treatment, based mainly on concerns of pin-tract infection and fracture nonunion, much of the clinical experience and basic science research results have proven the reverse. Many of the potential benefits of external fixation, such as the change of fixation stiffness, are not yet fully appreciated. Additional research and well-organized clinical trials must be performed. Pin-tract problems can be controlled, but the surgeon using such a device must be familiar with the techniques and follow the established regimens during postoperative care. One common mistake is to assume that external fixators, especially those of the simpler unilateral configuration, are easy to use and do not require learning or mastering the surgical techniques until the time of application. Periodic examination and radiographic evaluations are also essential to adjust conditions of the fracture site. The importance of balancing the biomechanical properties and the biologic consequences of different external fixation modalities has been demonstrated. Understanding this knowledge and the techniques of application associated with external fixation is the prerequisite to successful treatment. Some of the basic biomechanical information related to external fixation and bone fracture union is still unknown. This lack should provide the impetus for surgeons, bioengineers, and medical scientists to continue collaborative basic and applied research. Furthermore, by recognizing the proper cell mediators and the physical means to stimulate these cellular elements, the bone fracture healing process may be modulated, regardless of the fixation technique. The result of such effort should provide new modalities to improve fracture management.

Animals↗
PubMed2003

A comparison of monolateral and circular external fixation of unstable diaphyseal tibial fractures in children.

Forty-six tibial fractures in 44 children, which were treated by external fixation at our institution between 1 January 1991 and 31 December 1999, were retrospectively identified. Twenty-nine fractures were treated with monolateral fixation and 16 were treated with circular fixation. The average age of the patients was 11 years 8 months (range 3 years 11 months-17 years 7 months). External fixators were left in place for a mean of 13.7 weeks (range 9-33 weeks). Eleven significant complications occurred. Loss of reduction necessitating return to the operating room occurred in four patients (13%) and malunion occurred in an additional patient with monolateral fixators. Four of these patients had comminuted fracture patterns. All of the patients with loss of reduction were 12 years of age or older. No patient with a circular fixator developed mal-alignment. Final alignment in 45 of the 46 fractures was acceptable. External fixation is a safe and effective method of treating unstable diaphyseal tibia fractures in children. Patients over the age of 12 years, particularly with comminuted fracture patterns may be more effectively treated with circular external fixation or, if treated with monolateral fixation, require close observation.

Adolescent↗
PubMed1987

External fixation of complex carpal dislocations: a preliminary report.

In ten cases of complex carpal fracture dislocations an external fixator between the radius and the second or third metacarpals was used as an adjunct to open reduction and internal fixation. The external fixator facilitates reduction, ligamentous repair, and internal fixation of the carpal bones. Furthermore, continuous postoperative distraction of the wrist maintains a stable reduction of the carpus permitting cast free after treatment and early active motion of the neighboring joints. This method is particularly useful for carpal stabilization when combined injuries of the same extremity coexist.

Adult↗
PubMed1990

[Stabilization of open tibial fracture by an external fixator. Advantages through supplemental screw osteosynthesis].

One hundred thirty-two open tibial shaft fractures were treated by unilateral external fixation. In order to evaluate the usefulness of supplemental lag screw fixation, we compared forty-four reexamined fractures in which only external fixation was utilized with fifty-five reexamined fractures, stabilized with supplemental lag screws and external fixation. We did not find significant differences in time to full-weight bearing (17.1 vs. 15.6 weeks), time to union (18.7 vs 18.0 weeks), incidence of delayed union [as defined by time to union over 32 weeks (10.9% vs. 11.4%)], incidence of osteomyelitis (5.4% vs. 4.5%), or incidence of malunion [axial malalignment greater than 5 degrees (12.7% vs. 11.4%)]. Clinically significant differences were found demonstrating a twofold increase in refracture rate in the group with supplemental lag screws (10.9% vs. 4.5%) and requiring twice as many bone grafting procedures to achieve union (65.5% vs. 29.5) than did the group treated by external fixation alone. Therefore we do not recommend the routine use of supplemental lag screw fixation.

Adolescent↗
PubMed1991

[External fixator as primary and definitive treatment of tibial fracture with severe soft tissue damage].

The initial treatment of choice of fractures with severe soft tissue damage of the leg is the stabilization with an external fixator. After successful healing the question arises whether to continue the initial treatment with the external fixator to bone union or to change the initial concept by an internal fixation. Our experience with 62 fractures of the tibia (follow-up of 59 fractures) from 1985 to 1989 shows that 72% of the fractures were healed by the external fixator alone. Delayed union or pseudoarthrosis occurred in 17% and were mostly treated by late internal fixation. An analysis of the fracture types (new AO classification) did not show certain fracture types, that did not respond to the external fixator treatment alone. We conclude that the reason for a delayed union or pseudoarthrosis is less a morphological than a biological one. We recommend the first and final external fixator as treatment for fractures with severe soft tissue damage of the leg.

External Fixators↗
PubMed2000

[Distal radius fracture--is non-bridging articular external fixator a therapeutic alternative? A prospective randomized study].

A randomised prospective study was carried out to compare non-bridging external fixation using a small A0 external fixator with percutaneous Kirschner wire fixation and plaster in the treatment of distal radial fractures (A2/A3 in the A0 classification). The study involved 40 patients, 20 in each group. The advantages of the non-bridging fixation are: (1) early functional therapy of the wrist, (2) simplified reduction of the fracture, and (3) considerable less restriction of wrist mobility in day-to-day situations. Although the final examination 6 months after treatment showed almost identical functional results, the patients treated with the external fixator benefited from the fact that use of the wrist was virtually free throughout the entire treatment period.

External Fixators↗
PubMed1995

Single plane and biplane external fixators for knee arthrodesis.

Thirty-six knee arthrodeses performed using an external fixator with an average followup of 48 months were reviewed retrospectively. A single plane fixator was used in 19 cases and a biplane fixator in 17 cases. The reasons for fusion included an infected total knee arthroplasty (21 cases), aseptic loosening of a total knee arthroplasty (9 cases), posttraumatic osteoarthritis (3 cases), and a neuropathic joint, an infected unicondylar knee arthroplasty, and a tuberculous joint (1 case each). A fusion was obtained after the initial procedure in 22 patients (61%). With additional procedures, a fusion was obtained eventually in 27 patients (75%). The fusion rate decreased with an increasing number of prior knee procedures. Single and biplane external fixator designs had similar initial fusion rates (single 58%, biplane 65%). Complications included 14 nonunions (5 fused with additional procedures), 6 pin tract infections, 5 delayed unions, 1 stress fracture through a pin site, and 1 persistent infection resulting in an above-knee amputation. Despite biomechanical advances in external fixator design, knee arthrodesis remains difficult to achieve in patients who have had multiple previous procedures, a failed total knee arthroplasty, or an infected total knee arthroplasty with significant bone loss.

Adult↗
PubMed1999

Use of percutaneous transpedicular external fixation pins to measure intervertebral motion.

STUDY DESIGN: Direct measurement of intervertebral motion was compared to motion determined by measuring the position of the exposed ends of the external fixation pins. OBJECTIVES: To verify the accuracy of this technique, so that this protocol can be used to study intervertebral motion in the clinical setting. SUMMARY OF BACKGROUND DATA: The transpedicular external fixation test has been shown to be a test that can predict the outcome of spinal fusion. In patients who are candidates for this test, intervertebral motion can be calculated from motion at the external ends of these pins. METHODS: Six fresh cadaveric spinal segments from L2 to L5 were instrumented with titanium Schanz screws. Reflective markers were placed on the tips of the pins, and intervertebral motion was measured using a noncontacting camera system. Computed tomography data were used to determine the position of the vertebra relative to the reflective markers. Intervertebral distances were calculated and compared with direct measurements obtained using a three-dimensional digitizing arm. RESULTS: There was an excellent correlation (r2 = 0.931) between the directly measured intervertebral motions and those that were indirectly calculated from measurements of motion at the end of the Schanz screws. CONCLUSIONS: Intervertebral motion can be measured by monitoring motion of the ends of transpedicular external fixation pins. Motion of anatomic landmarks on the vertebrae can be calculated from the pin end's motion if computed tomography data are used to determine the geometric relation between the vertebrae and the external fixation pins. This validation study supports the use of this method in clinical investigations of intervertebral motion in patients with low back pain and external fixation.

Aged↗