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External fixation use in arthrodesis of the foot and ankle.

The use of external fixation in foot and ankle arthrodesis can be beneficial. Its advantages, disadvantages, and indications were reviewed in this article. External fixation offers the surgeon an opportunity to treat complex foot and ankle deformities, trauma, chronic infections, pseudoarthroses, soft tissue contractures, and limb length discrepancies in ways that were unavailable before its advent. The Ilizarov technique requires considerable experience and patient compliance for the best postoperative outcome. An understanding of musculoskeletal physiology and the biomechanics of bone and soft tissue are essential for the competent application of external fixators in general and Ilizarov frames in particular. The surgeon should be aware of all the surgical options before the application of an external complex apparatus.

Ankle Joint↗

The Orthofix external fixator for fractures of long bones.

The Orthofix external fixator was used to treat 112 fractures of the long bones in 101 patients, and 22 patients with infected nonunions. Our results compared favourably with those reported in other series where external fixation was used. The overall rate of uncomplicated union was 69.6% with 24.1% of patients requiring a further operation. The overall incidence of nonunion (30.4%) was due to the relatively large number of severe open fractures in the series. The apparatus was simple to apply, and safe and effective in practice. We recommend its use for the primary treatment of open and segmental fractures, and for infected nonunion.

Adolescent↗

A randomized, controlled trial of distal radius fractures with metaphyseal displacement but without joint incongruity: closed reduction and casting versus closed reduction, spanning external fixation, and optional percutaneous K-wires.

OBJECTIVES: To compare closed reduction and casting with closed reduction and external fixation with optional K-wire fixation for distal radius fractures with metaphyseal displacement but without joint incongruity. DESIGN: Prospective study. SETTING: Multicenter study at 3 University teaching hospitals. PATIENTS/PARTICIPANTS: A total of 113 skeletally mature patients with distal radius fractures with metaphyseal displacement, but without joint incongruity, were randomized to receive 1 of 2 standardized treatment protocols. Patients were evaluated at 6 weeks, 6 months, 1 year, and 2 years. INTERVENTION: Closed reduction and casting (n = 59) or closed reduction and external fixation (n = 54). MAIN OUTCOME MEASUREMENTS: Upper extremity function was measured using upper extremity MFA domain scores, overall Jebsen Taylor scores, and pinch and grip strength tests. Global function and pain were measured using the SF-36. Radiographic evaluation and range of motion were documented. RESULTS: Upper extremity MFA scores, Jebsen Taylor scores, SF-36 bodily pain scores, and grip strength improved significantly during the first year for all patients. By 2 years, mean Jebsen Taylor scores and SF 36 bodily pain scores for patients in both groups were similar to scores for normal age- and gender-matched population controls. At all points, there was a trend for better function in the external fixation; however, this did not reach statistical significance. There was a trend for better length and palmar tilt restoration with external fixation. CONCLUSIONS: For distal radius fractures with metaphyseal displacement but with a congruous joint, there exists a trend for better functional, clinical, and radiographic outcomes when treated by immediate external fixation and optional K-wire fixation.

Adult↗

[The use of dynamic axial external fixator with modified technique in Pilon fractures of tibial].

OBJECTIVE: To retrospectively analyses the results of dynamic axial external fixator with modified technique in the treatment of severely Pilon fractures. METHODS: From July 2000 to February 2003, 14 patients with severely Pilon fractures were treated with dynamic axial external fixator inserted with modified technique combined with limited open reduction and internal fixation with screws and Kirschner wires, with two distal external pins inserted into talus and calcaneus respectively so that the rotation axis of distal clamp was coincided with that of ankle joint. All patients were young or middle-aged people from 20 y to 52 y (average 38 y). All fractures were Rüedi-Allg were type II or type III. External fixators were removed after bone healing. Duration of follow-up was 5 - 36 m (average 18 m). RESULTS: The time of bone healing was 12 - 24 weeks (average 14 weeks). At the latest follow-up, results include 5 excellent, 6 good and 3 fair according to ankle scoring system (ASS). There was only one case of superficial pin site infection settled with oral antibiotics and pin site care with mild disinfectants. There was no wound breakdown, superficial and deep infection, osteomyelitis, fracture fragments redisplacement and collapse. CONCLUSION: Dynamic axial external fixator with modified technique combined with limited internal fixation is an effective method for the treatment of severely Pilon fractures.

Adult↗

Treatment of complex (Schatzker Type VI) fractures of the tibial plateau with circular wire external fixation: retrospective case review.

OBJECTIVE: To determine the effectiveness of circular wire external fixation in the treatment of complex (Schatzker Type VI) fractures of the tibial plateau. DESIGN: Retrospective case series. SETTING: Fifty-seven complex (Schatzker Type VI) fractures of the tibial plateau were treated with circular wire external fixation at a Level 1 trauma center. PATIENTS: Thirty-five fractures were closed, and twenty-two were open. INTERVENTION: Closed indirect reduction by ligamentotaxis was attempted in all fractures; limited open reduction was performed in seven. Conventional Ilizarov frames using wire fixation were used in thirty-two fractures. The remaining twenty-five fractures were treated with hybrid Ilizarov fixators, which differed from conventional Ilizarov frames only in the use of cortical bone pins rather than wires through the distal rings for fixation of the diaphysis. MAIN OUTCOME MEASUREMENT: The results were graded according to the Knee Society rating system. Follow-up ranged from 16 to 90 months and averaged 42 months. RESULTS: All fractures united at an average of 173 days (range, 50 to 415 days). Forty-five fractures with anatomic reduction had an average knee score of eighty-three and an average functional score of sixty-nine. In nine fractures with nonanatomic reduction, the average knee score was fifty-two, and the functional score was nineteen. CONCLUSIONS: Results perhaps would have been improved by more frequent open reduction, bone grafting, and internal fixation of fractures with severely depressed articular fragments. However, the use of circular external fixation obtained results comparable with other series, and we believe it is appropriate for treatment of these complex tibial fractures, especially those with a poor soft-tissue envelope.

Adolescent↗

[Arthroscopically assisted treatment of tibial plateau fractures by tractive reduction with external fixator].

OBJECTIVE: To study the clinical effect of tractive reduction with external fixator and arthroscopically assisted treatment for tibial plateau fractures. METHODS: From February 2003 to January 2005, a total of 26 cases with tibial plateau fractures were reviewed. There were 4 cases of type I fracture, 5 type II, 4 type III, 6 type IV, 5 type V and 2 type VI based on Schatzker criteria. Before operation, X-ray examination and CT scanning were done. During operation, the dissociative fragments were reconstructed by tractive reduction with external fixator arthroscopically and fixated with screws or plates. RESULTS: All the fractures were healed within 1.5 - 4 months, with no severe complications such as poor wound healing, infection or osteofascial compartment syndrome. All patients that were followed up for 7 - 21 months (mean, 16 months) showed no traumatic osteoarthritis, inversion or eversion of the knee. According to the Rasmussen scoring system, the outcome was excellent in 11 cases, good in 13 and fair in 2, with total score of 27 +/- 2. CONCLUSIONS: As for Schatzker type I - VI tibial plateau fractures, tractive reduction with external fixator and arthroscopically assisted treatment is characterized by minimal invasion, fast fracture healing. It broadens operative interspace of articular cavity, improves accuracy of reduction, is beneficial for knee joint function to recover.

Adult↗

Safety evaluation of large external fixation clamps and frames in a magnetic resonance environment.

Large orthopedic external fixation clamps and related components were evaluated for force, torque, and heating response when subjected to the strong electromagnetic fields of magnetic-resonance (MR) imaging devices. Forces induced by a 3-Tesla (T) MR scanner were compiled for newly designed nonmagnetic clamps and older clamps that contained ferromagnetic components. Heating trials were performed in a 1.5 and in a 3 T MR scanner with two assembled external fixation frames. Forces of the newly designed clamps were more than a factor 2 lower as the gravitational force on the device whereas, magnetic forces on the older devices showed over 10 times the force induced by earth acceleration of gravity. No torque effects could be found for the newly designed clamps. Temperature measurements at the tips of Schanz screws in the 1.5 T MR scanner showed a rise of 0.7 degrees C for a pelvic frame and of 2.1 degrees C for a diamond knee bridge frame when normalized to a specific absorption rate (SAR) of 2 W/kg. The normalized temperature increases in the 3 T MR scanner were 0.9 degrees C for the pelvic frame and 1.1 degrees C for the knee bridge frame. Large external fixation frames assembled with the newly designed clamps (390 Series Clamps), carbon fiber reinforced rods, and implant quality 316L stainless steel Schanz screws met prevailing force and torque limits when tested in a 3-T field, and demonstrated temperature increase that met IEC-60601 guidelines for extremities. The influence of frame-induced eddy currents on the risk of peripheral nerve stimulation was not investigated.

External Fixators↗

External fixation for the foot and ankle in children.

During the last decade, external fixation for the pediatric foot and ankle has evolved as a result of advances in technology (eg, Taylor spatial frame, hydroxyapatite-coated external fixator pins) and preoperative deformity planning. Although complications are common, most are minor and can be addressed nonoperatively while treatment continues. This article reviews the indications and applications of external fixation for soft tissue contractures, idiopathic and teratologic clubfoot, osteotomies, metatarsal lengthening, tibial lengthening, and foot and ankle trauma.

Bone Lengthening↗

Principles of external fixation and supplementary techniques in distal radius fractures.

External fixation for fractures of the distal radius has been used for almost 80 years. The main objective is to gain reduction and maintain the reduction throughout the treatment period. Several fixator concepts are available and selection is based on the complexity of the injury to be treated as well as the surgeon's experience. Periarticular application of the fixator with immediate use of the wrist joint is recommended whenever possible. For intra-articular fractures, transarticular application is advisable. External fixtion in complex fractures has to be supplemented by bone grafting, fixation wires and stabilization of the radioulnar joint. Associated injuries in distal radius fractures need to be identified and treated. The possible complications of external fixation and the means to prevent them are discussed. External fixation of the distal radius has found its place as an established method in treating certain types of this common fracture.

Adolescent↗

A biomechanical strength comparison of external fixators.

BACKGROUND: The purpose of this study was to biomechanically test the current commercially available uniplanar, half-pin external fixators, comparing stiffness, weight, and cost. METHODS: The Hammer, HexFix, Hoffmann, Monotube Blue, Monotube Red, Torus, TraumaFix, and Ultra-X were tested using previously published methods. The Instron 4500 was used to assess the strength characteristics in axial, torsional, anteroposterior, and lateral bending of each device. Weight was based on the unassembled fixator construct. Cost was determined from the purchase price of each individual fixator. RESULTS: The results of this study revealed that the Torus was the stiffest external fixator tested in torsion. The Monotube Red was the stiffest in axial loading, anteroposterior bending, and lateral bending. The Hammer and Hoffmann external fixators were the heaviest constructs. The Torus and HexFix were the most expensive. CONCLUSION: Many factors, including stiffness, weight, cost, ease of application, fracture characteristics, and personal preference, go into deciding which external fixator to use. The data presented compare stiffness characteristics of several fixators under standardized loading conditions. These data indicate that the Torus and Monotube Red provide the greatest stiffness when comparing all modes of failure.

Biomechanical Phenomena↗

Fracture site motion with Ilizarov and "hybrid" external fixation.

OBJECTIVES: To evaluate differences in fracture site motion by using different external fixators. DESIGN: A wooden dowel was used to simulate a long bone with a transverse diaphyseal fracture. Ilizarov, "hybrid," and strutaugmented "hybrid" external fixation was used to stabilize the "fracture." The wooden dowel was subjected to separate axial, four-point bending, and torsional loads. Fracture site motion in the axial plane, off-axis motion (shear and bending), and rotation were measured. SETTING: All mechanical testing was performed with a sevohydraulic test frame (MTS Systems, Minneapolis, MN, U.S.A.). Fracture site motion was measured with an interfragment motion device developed in this laboratory. INTERVENTION: Comparison was made between a traditional fourring Ilizarov fixator, a "hybrid" fixator using rings and threaded pins attached by a unilateral aluminum bar, and a "hybrid" fixator augmented with a V-shaped strut. MAIN OUTCOME MEASUREMENT: Load-deformation behavior in axial displacement, shear displacement, and bending displacement were compared between the different configurations under identical conditions of axial loading, torsional loading, and four-point bending. In torsional loading, rotational displacement was also measured. RESULTS: The Ilizarov configuration allowed significantly less off-axis fracture site motion in all loading modes than either "hybrid" configuration while still allowing axial compression of the fracture ends. CONCLUSIONS: In a completely unstable fracture with poor bone apposition, the mechanical behavior of a four-ring Ilizarov external fixator is superior to the mechanical behavior of a unilateral "hybrid" frame.

Biomechanical Phenomena↗

In vitro effects of external fixation on intact and osteotomized tibiae. A biomechanical study.

In order to study the in vitro mechanical effects of external fixation on intact and osteotomized bone, human and rabbit tibiae were tested in three-point bending in an Instron testing machine. Intact tibiae were loaded in the elastic range before and after application of an external fixation device. In the human specimens the Vidal-Adrey double frame was used, and in the rabbit specimens the external mini-fixation. The bone deformation in the anteroposterior direction was measured with a linear voltage differential transformer. After application of external fixation a median bone elastic stiffness of 110.2 per cent in human tibiae and of 106.1 per cent in rabbit tibiae was found, in relation to the stiffness of intact tibiae without external fixation. The stiffness increase was significant in human specimens, but not significant in rabbit specimens. In osteotomized human tibiae fixed with the Vidal-Adrey double frame a median stiffness of 8.5 per cent of the stiffness of intact bones was found when compression was not applied, compared to 19.9 per cent when compression was applied. In rabbit tibiae a median stiffness of osteotomized bones with external mini-fixation was 8.9 per cent of the stiffness of intact bones. There was a good agreement between the results in rabbit tibiae with the mini-fixation and human tibiae with external fixation without compression. The external mini-fixation thus seems to be a suitable model for the study of bone healing in rabbit tibiae.

Aged↗

Spread of infection, in an animal model, after intramedullary nailing of an infected external fixator pin track.

Implant sepsis. due to previous external fixator pin track infection, is the most common complication of secondary intramedullary (IM) nailing of the tibia. We have developed an animal model, which allows different treatment methods to be studied. Using an established ovine model of a pin track infection, Staphylococcus aureus was used to infect the external fixator pins, two weeks prior to reamed IM nailing. In the control group, the animals were killed at a mean of 10.5 days following nailing, when widespread infection was evident, with septic arthritis, abscess formation, and infection of the entire length of the tibia in all six animals. In the treatment group, before IM nailing, the pin sites were debrided, and both local and systemic antibiotics were administered. All surgical wounds healed without evidence of infection, 4 of the 6 animals survived for 28 days, and bacteria were only isolated from 1 of the 6 implants. Treatment was successful at reducing, but not eliminating, infection after secondary nailing.

Animals↗

Recovery of muscles of old rats after hindlimb immobilisation by external fixation is impaired compared with those of young rats.

The right hindlimbs of 24-month-old female Wistar rats were immobilised for 4weeks using external fixation of the knee joint. In a further group, after the external fixation was removed, the rats were allowed to remobilise for an additional 4weeks. Hindlimb immobilisation for 4weeks caused a 32-42% reduction in wet weights of the hindlimb muscles of the rats as compared to those of the contralateral non-immobilised legs. After 4weeks of remobilisation the hindlimb muscles had not returned to the "control" weights. Biochemical changes in the gastrocnemius muscle resulting from the external fixation showed greatly elevated acid phosphatase activities (33.2%) and markedly reduced creatine phosphokinase activities (17.2%), which did not recover to preimmobilisation values after 4weeks of remobilisation. Light and transmission electron microscopy showed that remobilisation for 4weeks (after external fixation) resulted in only partial morphological restoration of the damage to the muscles in these aged rats. A comparison of similar hindlimb external fixation and remobilisation in young (6months old) rats showed that remobilisation caused a substantial recovery in biochemical parameters in both age groups, with the muscles of the young group (but not the old group) often reaching almost complete recovery accompanied by morphological restoration. We conclude that the net gain in the recovery period of biochemical and morphological parameters is significantly greater in the young rats compared to the old rats indicating that muscle metabolism and capacity for recovery from disuse atrophy is impaired with ageing.

Aging↗

Load relaxation and forces with activity in Hoffman external fixators: a clinical study in patients with Colles' fractures.

A small-frame Hoffman external fixation bar instrumented with strain gauges to quantify bending and torsional forces was applied to 4 patients with a displaced metaphyseal fracture of the distal radius. Measurements were taken during surgery as well as at 1, 3, and 6 weeks after surgery during activities of daily living and hand therapy mobilization. Radiographs also were taken before and after reduction and at each subsequent visit. Force decay occurred after reduction of the fracture, averaging only 26% of the initial distraction forces by 5 minutes. These forces plateaued and did not significantly change over the subsequent 40-minute observation period. There was no correlation between carpal height index and the forces measured in the external fixator. Significant changes in external fixator forces were measured during activities of daily living and hand therapy mobilization, but these returned to baseline after the activities were performed. The most provocative activities studied were twisting a doorknob and lifting heavy objects. These activities should be performed with caution by patients with unstable distal radial fractures.

Activities of Daily Living↗

Cast or external fixation for fracture of the distal radius. A prospective study of 126 cases.

In a prospective 4-year study, 126 consecutive patients with a fracture of the distal radius were followed. Functional, anatomic, and radiographic final results of fixation with above-the-elbow cast immobilization were compared with the results obtained with external fixation. The results following external fixation of comminuted intraarticular fractures were better than those of similar fractures treated in a cast. Aged osteoporotic patients tolerated better residual deformities, and the clinical results had a relatively low correlation with the final anatomic alignment. We suggest that extraarticular fractures of the distal radius should be treated with cast immobilization. Comminuted intraarticular fractures of the distal radius should be treated with external fixation, which maintains accurate anatomic position until solid fracture healing is achieved.

Adult↗

Comparison of the effects of compression plates and external fixators on early bone-healing.

We used two mechanically dissimilar devices, compression bone-plates and unilateral-frame external fixators, in a standard canine osteotomy model; both methods were highly successful in achieving mature bone union. Bone union was studied by histological, physiological, and biomechanical means. At 120 days after injury, union was biomechanically less mature on the external fixator side. These tibiae had less intracortical new-bone formation (p less than 0.01), more bone resorption (p less than 0.045), and more bone porosity (p less than 0.04) when compared with paired tibiae that had been treated with compression plates. This higher level of bone turnover on the external fixator side was accompanied by an increase in blood flow (measured by clearance of 85Sr) (p less than 0.04). At the osteotomy site, pre-experimental or unlabeled bone and porosity were greater on the external fixator side and endosteal new-bone formation was greater on the plated side. Since the in vitro stiffness of the external fixator was less in all modes tested (compression, distraction, torsion, and anteroposterior bending) except lateral bending, it may be that the rigidity of the fixation is an important factor in early bone-remodeling of a healing osteotomy.

Animals↗

Complications of treating distal radius fractures with external fixation: a community experience.

OBJECTIVE: To analyze the immediate postoperative complications associated with treating distal radius fractures with external fixation. DESIGN: A retrospective chart review of data obtained from 24 consecutive patients who were treated with small AO external fixators in 1997. SETTING: Two community medical centers. INTERVENTION: Preoperative and postoperative radiograph measurements were taken of radial inclination, radial tilt, and radial length, and fractures were classified according to the AO system. Patient charts were reviewed to document demographics, type of fixator used, open or percutaneous technique for pin placement, use of augmentation, additional operations, and complications. MAIN OUTCOME MEASUREMENTS: Complications associated with treating distal radius fractures with one type of external fixator. RESULTS: Sixteen of the 24 patients had complications: 5 with neuropathies of the median or superficial radial nerve, 9 with pin track infections, 2 with pin loosening, one with a nonunion, 2 with malunion, and 4 patients each with radial shortening, loss of radial tilt, collapse of ulnar border or volar intercalated segment instability (VISI) of the lunate and rotatory subluxation of the scaphoid. CONCLUSIONS: Postoperative complications following distal radius fractures treated with external fixation are common. Their effect, however, on long term functional results and patient satisfaction is negligible, with the exception of those patients with complications intrinsic to the fracture itself, i.e., nonunion, malunion or carpal malalignment.

Adult↗