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PubMed1993

Pin placement in pelvic external fixation.

Early external fixation of major pelvic fractures reduces haemorrhage and mortality. The best site and method for pin placement remains unresolved. The superior iliac crest is biomechanically disadvantageous and hinders access to the abdomen. Low pin placement between the anterior iliac spines has been proposed as a better solution. A case-controlled study was performed on cadavers using a jig designed to place external fixator pins accurately in the pelvis; the study tested the safety of pin placement and the mechanical strength of the two placement sites. The results showed that pins could be placed safely using this method and that low placement in cadaveric bone is as strong as that of the conventional placement.

Biomechanical Phenomena↗
PubMed2003

A comparison of two military temporary femoral external fixators.

Temporary external fixation of femur fractures, used at civilian trauma centers for patients who cannot tolerate more extensive procedures, also is planned for use in military field hospitals to provide temporary stabilization and allow for safe transport of a patient to the next level of care. The purpose of the current study was to evaluate three constructs: an external fixator made by one manufacturer and two Hoffman II constructs: uniplanar and biplanar. The study consisted of two parts: a biomechanical study of each of the three constructs and the application of each of the two Hoffmann II constructs to separate cadaver thighs by resident surgeons. Five resident surgeons participated in the study using five pairs of cadaver thighs. The biplanar construct was stiffer in axial and torsional stability when compared with the uniplanar construct. There was no difference in the amount of time needed to apply the constructs nor was either construct found to be subjectively easier to apply by the surgeons. There was an increased number of unicortical pins and plunges (when a pin inadvertently slips over the side) with the uniplanar construct when compared with the biplanar. The biplanar construct is biomechanically more stable and appears to allow for more accurate placement of pins.

Biomechanical Phenomena↗
PubMed1989

[Superior radio-cubital congenital synostosis. Computed tomographic scanning studies and value of osteotomy fixation using an external fixator].

The purpose of this case report was to describe the radiological features by computed tomography and a modification in the fixation of the rotation after the usual transverse osteotomy: an external fixation was used; it allows post-operative vascular assessment with the possibility to derotate the correction in case of circulatory or neural impairment.

Adolescent↗
PubMed2003

Mechanical performance of hybrid Ilizarov external fixator in comparison with Ilizarov circular external fixator.

OBJECTIVE: The aim of this study was to determine the stiffness characteristics of the standard and hybrid Ilizarov fixators. DESIGN: Five different frame models (one standard and four hybrid Ilizarov) were designed. Four full rings were used in the standard Ilizarov frame. Two rings were placed proximal and two rings were placed distal to the osteotomy line with two wires at 90 degrees to each other on each ring. The distal tibial fixation of all the hybrid configurations and standard Ilizarov fixator were the same, and only the proximal fixations were different. In hybrid models, different numbers of 90 degrees femoral arches (1-3) were fixed to the proximal segment by using the half-pins with different numbers (2-4) and different angles to each other (45 degrees and 90 degrees ). BACKGROUND: Numerous investigations have been performed to compare the mechanical properties of different frames. The Ilizarov method of fracture fixation and limb lengthening has recently gained international recognition. But its application is difficult in some anatomic localization, so that hybrid ring fixation frames of various configurations are gaining clinical popularity. METHODS: Five different frame models were applied to the sheep tibial bones. The midpoint of the tibial bones was osteotomised and the osteotomy distracted for 2 cm. Four identical samples for each model were created and each identical sample of each model (n=1) were tested four times in axial compression, antero-posterior and medio-lateral bending, and torsion. RESULTS: In standard Ilizarov fixator, axial and bending stiffness was found to be more than all hybrid Ilizarov fixator models. Between the hybrid fixators, higher axial and bending stiffness was found when the number of femoral arches and half-pins were increased. Different angles between the half-pins formed 67% alteration in medio-lateral bending stiffness. No significant difference was found for torsional stiffness between the fixator models. CONCLUSIONS: For optimum fixator stiffness in hybrid fixators, at least three femoral arches and four half-pins must be used and these half-pins should be placed at 90 degrees angles and at different planes to each other. However, it should be remembered that, hybrid fixator models had less axial and bending stiffness than standard Ilizarov fixator model. RELEVANCE: For optimum fixator stiffness in hybrid fixators, at least three femoral arches and four half-pins must be used. However, it should be remembered that, hybrid fixator models had less axial and bending stiffness than standard Ilizarov fixator model.

Animals↗
PubMed1983

[Intramedullary nailing as secondary intervention following prior use of external fixation].

The external fixation has its clear indications. In some cases, however, healing up of the bone fails to appear. This is caused partly by the gravity of the primary injury, partly by biomechanical reasons. The failure of a perfect fracture healing can require a change of the osteosynthesis procedure. Under certain conditions nailing provides good success. By means of 13 own cases conditions, indications and results of secondary nailing after prior external fixation osteosynthesis will be discussed.

Adult↗
PubMedDate not supplied

[Stiffness of the AO spinal external fixator. Experimental results of stiffness of the AO spinal external fixator with 3 different pedicle screw systems].

The stiffness of the AO external pedicular fixator was analysed in an experimental laboratory study using three different sets of pedicle screws and different configurations of the implant. The experiments were performed with a wooden model as well as with bi-segmental human lumbar spine specimens with disc and ligaments intact. The capacity of the AO external pedicular fixator to compensate axial load, transversal- and torsion forces was compared to physiological requirements. Of particular interest was the effect of preload on the axial stiffness. It is demonstrated that the axial stiffness of the AO external pedicular fixator is so low that the axial load on the lumbar spine level in humans cannot be influenced by the fixator even when preloaded. However the resistance against torsion and transversal slipping is probably higher than required in vivo. No significant differences were found between the three types of pedicular screws. The effect of the triangular counter nuts of the AO external pedicular fixator on the transversal- and torsion stability was important. The presented results suggest that the AO external pedicular fixator can be of significant value in segmental rotation- and translocation pathologies of the lumbar spine and that the effect of isolated segmental distraction has probably been overestimated.

Bone Screws↗
PubMed1996

[Secondary internal osteosynthesis after external fixation for recent or old open fracture of the lower limb].

PURPOSE: The purpose of our study is to analyse the indications, results and limits of secondary internal fixation after external fixation for open fracture of the lower limb. MATERIAL: Our series covered 21 patients treated between 1991 and 1994. There were 17 men and 4 women. Tibia was affected 17 times and femur 5 times (one bifocal fracture). In Gustilo's classification, we had 1 case of type 1, 12 of type II and 8 of type III. METHODS: We used 15 times the FESSA External Fixator and 6 times a monotube external fixator in emergency. We have done secondary 11 intra medullary nailing and 11 patients were treated by plating (one patient had both) 13 patients had a bone graft (cortico-cancellous graft). In the first group of patients (10 cases), the initial treatment gave us good results for both skin and bone healing. The external fixation was replaced by an internal one in order to accelerate bone consolidation and to allow an early weight-bearing. Removal of the external fixation was made at an average of 4 months postoperative. In the Second group (11 cases) the internal fixation was proposed because of an insufficiency of the external fixation leading to complications as: non union, mal union and bone defects. External fixation was removed in a mean time of 8 months. Internal fixation was completed by local bone autograft. RESULTS: 17 patients have been reviewed. Consolidation occurred with an average of 6 months after internal fixation 1 to 24 months. We had no deep infection but only 2 superficial ones. DISCUSSION: We chose 2 types of indication, and we called them programmed and for necessity. The first group of 10 patients whose stain was moderate and whose initial setting up had permitted a perfect anatomic reduction with a rapid wound healing. Internal fixation was performed after a short duration of external fixator. An early weight bearing was allowed so that the functional recovery could be obtained quickly. The second group is represented by patients whose internal fixation was done for non union, malunion or bone defect. In such a case autogenous cancellous graft was used to fill the defect.

Adolescent↗
PubMed1996

[External fixation of bones (fixateur externe) in fracture treatment].

In traumatology, we differentiate between conservative and surgical treatment. External fixation of the bone lies somewhere between the two. When deciding on the most appropriate treatment for each patient, the advantages and disadvantages must be carefully evaluated. However, there are a series of single or multiple injuries which can't be optimally treated with conservative procedures nor with invasive surgery. External fixation has become the treatment method of choice in many of these cases. The fragments to be stabilised are fixed with (so-called Schanz screws) or with (Steinmann pins) or with wires. The section which lies outside the body are attached to longitudinal rods. External fixation is a noninvasive, surgical method of fracture stabilisation with many advantages is easy to handle, has a low complication rate, can be taught anywhere, and can be used everywhere. There are great advantages in cases of soft tissue damage, in polytraumatised patients and in septic orthopedic surgery.

Equipment Design↗
PubMed1994

Dynamic external fixation of unstable fractures of the distal part of the radius. A prospective, randomized comparison with static external fixation.

A prospective, randomized study was done to compare the results of dynamic external fixation (the Clyburn device) with those of static external fixation (the AO/ASIF device) in the treatment of fifty unstable fractures of the distal part of the radius. Mobilization of the wrist from neutral to 30 degrees of flexion was begun in the dynamic-fixator group at approximately two weeks, and full motion, allowing 30 degrees of extension, was started at approximately four weeks. The external fixation frames in both groups were kept in place for approximately ten weeks. Mobilization of the wrist in the dynamic-fixator group provided little gain in the mean motion of the wrist at the time of the removal of the fixator or at the one, six, or twelve-month evaluation. The static-fixator group had greater flexion of the wrist and radial deviation at the early and late follow-up examinations, while the dynamic-fixator group demonstrated only greater ulnar deviation one month after the fixator had been removed. Motion of the wrist in the dynamic-fixator group resulted in a statistically significant loss of radial length compared with that in the static-fixator group (four millimeters compared with one millimeter, p < 0.001). Complications were more frequent in the dynamic-fixator group. As evaluated with a modification of the scoring system of Gartland and Werley, 92 percent of the results at one year were excellent or good in the static-fixator group and 76 percent, in the dynamic-fixator group. The results of this study cannot support the concept of early mobilization with a dynamic external fixator for the treatment of unstable fractures of the distal part of the radius.

Adult↗
PubMed2005

Fixation stiffness of Dynafix unilateral external fixator in neutral and non-neutral configurations.

A primary function of external fixator is to stabilize the fracture site after fracture reduction. Conventional fracture reduction method would result in fixator configurations deviated from its neutral configuration. How the non-neutral configurations would affect the biomechanical performance of unilateral external fixators is still not well-documented. We developed a finite element model to predict the fixation stiffness of the Dynafix unilateral external fixator at arbitrary configurations under compression, torsion, three-point, and four-point bending. Experimental testing was done to validate the model using six Dynafix unilateral external fixators in neutral and particular non-neutral configurations. Effects of loading directions on bending stiffness were also studied. It appeared that the model succeeded in revealing the relative stiffness of the neutral and non-neutral configuration in all the loading conditions. Our results also demonstrated that bending stiffness could vary substantially for different loading directions and the principle loading directions could be very different for different fixator configurations. Therefore, a more logical way to compare the bending stiffness is to identify the principle loading directions of each fixator configuration and used their maximum and minimum bending stiffness as comparison criteria. Given that fixator configurations could substantially change the stiffness properties of the bone-fixator system, computer simulation with finite element modeling of this kind will provide useful clinical information on the rigidity of certain configurations in stabilizing the fracture site for bone healing.

Computer Simulation↗
PubMed2000

The effects of different wire and screw combinations on the stiffness of a hybrid external fixator.

Hybrid external fixators that use tensioned wires in the metaphysis and screws in the diaphysis combine the advantages of both unilateral and circular fixators and provide considerable flexibility in frame construction. This study aims to determine the effects of wire and screw combinations on the mechanical characteristics of such systems. Acrylic rods were used to simulate a long bone with a transverse fracture gap. A standard hybrid fixator design was used to stabilize the fracture in accordance with modern concepts with wires being used on one side of the fracture and screws on the other side. Twelve different wire and screw combinations were tested in axial compression and four-point bending in two planes. All the fixators tested demonstrated stiffening under increasing axial load, the extent of which appeared to correlate inversely with the number of wires used. Increasing the number of wires by one increased the axial stiffness by 7-16 N/mm (average 11 N/mm). The bending stiffness was largely controlled by the number of wires and increased by 0.42-1.03 N m/mm (average 0.74 N m/mm) for each additional wire. The axial stiffness of fixators with three screws was 4-7 N/mm (average 6 N/mm) higher than those with two screws if the offset screw was not in use. When the offset screw was used no stiffness advantages were found for three screws over two screws. The use of an offset screw substantially increased axial stiffness (by 12-26 N/mm, average 20 N/mm) and is recommended for unstable fractures. The two-ring hybrid fixators with four wires in one ring and three screws in the other had stiffness characteristics similar to the conventional four-ring Ilizarov fixator. Knowledge gained regarding the effects of wire and screw combinations on overall stiffness will be helpful both in the construction of frames and in destabilization during fracture healing.

Biomechanical Phenomena↗
PubMed2005

Knee stability after articulated external fixation.

BACKGROUND: Articulated external fixation has been proposed as a method to protect ligament reconstructions while allowing aggressive and early postoperative rehabilitation after knee dislocation. However, the ability of these fixators to protect and stabilize the knee joint has not been clearly determined. HYPOTHESIS: Articulated external fixation can reduce anteroposterior translation in the cruciate-deficient knee and reduce cruciate ligament strain in cases of intact or reconstructed ligaments. STUDY DESIGN: Controlled laboratory study. METHODS: Knee stability was assessed by 3 standard clinical stability tests (Lachman, anterior drawer, and posterior drawer) on 7 human cadaveric lower extremities. Instrumented forces of 100 N were applied to the tibia to measure cruciate ligament forces and tibiofemoral displacement in intact and cruciate-deficient specimens with and without articulated external fixation to determine the degree to which a fixator can protect cruciate ligaments and stabilize the knee. Articulated external fixation was applied using monolateral and bilateral fixators to comparatively analyze the effectiveness of each construct. Statistical analysis was performed using 2-tailed, paired Student t tests. RESULTS: Application of the monolateral articulated external fixator to specimens with intact ligaments significantly reduced cruciate ligament forces by 1.0 N (P = .011), 1.7 N (P = .046), and 1.4 N (P = .009) for Lachman, anterior drawer, and posterior drawer tests, respectively. In the cruciate ligament-deficient knees, the application of a monolateral fixator significantly reduced tibiofemoral translation by 49%, 70%, and 46% for Lachman, anterior drawer, and posterior drawer tests, respectively. No significant differences between the monolateral and bilateral fixator frames, in terms of ligament protection and joint stabilization, were observed. CONCLUSION AND CLINICAL RELEVANCE: Articulated external fixation of the knee can reduce stress in the cruciate ligaments after multiligament reconstructions and can decrease anteroposterior translation in the cruciate-deficient knee.

Aged↗
PubMed2003

The history of external fixation.

Even though external fixation is considered to be a rather "new" trend in orthopedics and traumatology, in fact it has been something used by physicians and surgeons for thousands of years. In the mid 1800's, external fixation would see some substantial growth and evolution, pioneered by physicians and surgeons whose principles are still in use today. Through the 1900's, the indications and usage would continue to expand, not to mention the modernization of the external fixation apparatus. Many surgeons in this era are notable for their work with external fixation, especially Gavriel Ilizarov, considered to be the father of external fixation. Further research and development with external fixation needs to be performed and, with time, will more than likely become fully integrated into modern clinical practice.

External Fixators↗
PubMed1985

External fixation of tibial shaft fractures. A review of 42 fractures by the Hoffman-Vidal-Adrey external fixation system.

Over a 6-year period (1977-1983), 59 patients with 61 tibial shaft fractures were treated by external fixation. Of these patients, 42 with 42 fractures were followed up until solid union. Thirty-seven fractures were caused by high-energy impact, mainly road accidents. Seventeen fractures were closed and 25 were open. In 33 patients an external quadrilateral frame system was applied primarily, and in the remaining nine within 1-2 weeks. No predrilling was done, and in 16 patients nonthreaded connection rods were used throughout the period in the fixator. The process of union was monitored by repeated noninvasive measurements of stability. Average time form injury to dismantling of the external fixation was 5.2 months (range 2-12.5 months) and time-to-union for the whole series was 10.0 +/- 5.5 months (range 4-31 months). Sixteen fractures failed to unite. Compared with other published series treated by external fixation, the incidence of non-union in the present series is high. On the basis of the present findings it is concluded that a compression device should be mounted either primarily or as soon as possible during the process of union, and that compression should be applied at regular intervals. If an external fixator is used, the surgeon must bear in mind the possible complications. It is probably safer to reduce rather than to prolong time-to-removal of the external system.

Adolescent↗
PubMed2002

Improvement of external fixator performance in type C pelvic ring injuries by plating of the pubic symphysis: an experimental study on 12 external fixators.

BACKGROUND: In an earlier study, we introduced a pelvic ring stability criterion for weightbearing stabilization. In a loading test, however, current external fixation systems alone did not meet this criterion. Internal fixation of the dorsal ring can significantly increase stability, but the condition of severely injured patients is often a contraindication for major surgery. The aim of this study is to optimize external pelvic ring fixation without dorsal ring stabilization to allow weightbearing in early mobilization of patients with unstable pelvic ring injuries. METHODS: The stiffness of external fixation systems alone and in combination with one or two anterior plates was measured by using a pelvic replica with a type C pelvic ring injury. Endpoints were 15 mm of dislocation or tolerance of 560 N. RESULTS: Addition of one plate at least doubles stiffness, whereas two-plate fixation results in at least a fourfold stiffer configuration. Frame configurations profit more than single-bar systems, and all but one system resist the weightbearing load after double-plating of the pubic symphysis. CONCLUSION: The choice of double-plate fixation of the anterior ring in addition to external fixation results in weightbearing capacity.

Biomechanical Phenomena↗
PubMed1999

Combined limited internal fixation with circular frame external fixation of intra-articular tibial fractures.

High-energy intra-articular fractures of the tibial plateau and plafond cause ongoing management problems for the orthopedic surgeon. This study retrospectively evaluated 37 such fractures treated with limited internal fixation and circular frame external fixators. Seventeen plateau fractures (5 open) and 20 plafond fractures (9 open) were treated. Time to union, number of procedures, complications, and functional outcomes were evaluated. All tibial plateau fractures healed within an average of 3.8 months. Eighteen of 20 plafond fractures healed at an average of 4.8 months. There was a high complication rate as is common with these injuries, but most of the complications were minor and easily treated.

Adult↗
PubMed2003

Treatment results for open comminuted distal humerus intra-articuler fractures with Ilizarov circular external fixator.

In open, intra-articular distal humerus fracture caused by gunshot injury, full functional recovery is difficult to obtain. Three basic treatment methods are available: minimal internal fixation, open reduction-internal fixation, and external fixation. In Gülhane Military Medical Academy Department of Orthopedics and Traumatology, 19 of 20 cases of gunshot injuries were treated with circular external fixator between the January 1995 and December 2000. Nine (45%) cases were type III-A, eight (40%) were type III-B, and three (15%] were type III-C. Eight (40%) cases were brought to the hospital 6 to 8 hours after the injury and 12 (60%) were in late stage. An amputation was done in one case. Mean follow-up period was 34.3 (14-55) months. Union was achieved in all 19 of the cases, and circular external fixator was taken out in a mean period of 4.6 (3-7) months. In the early treatment group, three (42.9%) were good, three (42.9%) were moderate, and one (14.2%) was unsatisfactory. In the late treatment group, five (41.7%) were good, four (33.3) were moderate, and three (25%) were unsatisfactory. Circular external fixator can be preferred as a treatment alternative in selected cases of distal humerus intra-articular open communited fractures because it protects the soft tissue connections and blood circulation of bone fractured, permits early elbow movements, and allows the patient to return to daily life very early.

Adult↗