Eur J Trauma Emerg Surg DOI 10.1007/s00068-013-0362-7
ORIGINAL ARTICLE
Crossover external fixator for acetabular fractures: a cadaver study M. Frank • V. Dzupa • K. Smejkal V. Baca • T. Dedek
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Received: 21 December 2012 / Accepted: 1 December 2013 Ó Springer-Verlag Berlin Heidelberg 2013
Abstract Background Dislocated acetabular fractures in polytraumatized patients are very challenging cases to deal with. Temporary stabilization by skeletal traction is difficult in these patients. A more effective solution can be an external fixation. Objective The authors designed a new crossover external fixation frame for acetabular fracture. The aim of this study is the biomechanical testing of this frame on human cadavers. Methods This study is an experiment on ten human cadavers. The acetabular fracture C2.2 was created. The stabilization effect of external fixation was compared with stabilization by large distractor. Femoral heads’ shifts caused by standardized manipulation with the cadaver were obtained from X-ray pictures. Results The mean total shift in stabilization technique by external fixation was 2.56 (1–4) mm. In stabilization by large distractor, the mean of the total shift after cadaver M. Frank (&) K. Smejkal T. Dedek Department of Surgery, University Hospital Hradec Kralove, Sokolska 581, Hradec Kralove 500 05, Czech Republic e-mail:
[email protected] V. Dzupa Department of Orthopaedics and Traumatology, Third Faculty of Medicine of Charles University and University Hospital Kralovske Vinohrady, Prague, Czech Republic K. Smejkal Department of Field Surgery, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czech Republic V. Baca Department of Anatomy, Third Faculty of Medicine of Charles University, Prague, Czech Republic
manipulation was 5.11 (0–10) mm. No significant differences were found between stabilization by external fixation and by large distractor (p = 0.066). Conclusions The stabilization of acetabular fracture C2.2 by a crossover external fixator is as effective as large distractor. The crossover external fixation could be a suitable solution for the temporary stabilization of acetabular fractures in polytraumatized patients. Subsequent studies including clinical trials are necessary to confirm the authors’ suggestion. Keywords External fixation Acetabular fracture Polytrauma Cadaver
Introduction Acetabular fractures are often caused by high-energy trauma [1]. The associated injuries of the brain, abdomen, chest and extremities occur frequently [1–4]. A combination of acetabular fracture with pelvic ring fracture is not rare [5, 6]. In this type of patient, dealing with the acetabular fractures is troublesome. Although acetabular fractures require fewer blood transfusions and are not commonly associated with hemodynamic instability in contrast to pelvic fractures [6], systemic inflammatory response syndrome (SIRS) can occur due to associated injury. Many authors advocate an early open reduction and internal fixation strategy for acetabular fractures due to reduced hospital stay and improved functional outcome [7]. This approach is often not possible and definitive osteosynthesis has to be delayed for a few days. The main reason for this is the patient’s general health condition [1]. In the last decade, the advance in molecular medicine with possible quantification of SIRS indicates the necessity of early
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M. Frank et al. Fig. 1 Acetabular fracture (left side affected) with serious posterior instability in a polytraumatized patient, who suffered from progressive sciatic nerve palsy: a computed tomography (CT) scan after reduction with skeletal traction being applied; b, c CT scans after repeated reduction with an external fixator spanning the left hip joint applied; d clinical view of this external fixator frame
fracture stabilization [1]. Although studies discussing Damage Control Orthopaedics Surgery deal with the management of long-bone fractures [8, 9], the same principles should be applied to pelvic and acetabular fractures. An additional problem related to acetabular fractures is dislocation of the femoral head. A dislocated femoral head is at risk of avascular necrosis and sciatic nerve palsy, which can occur due to prolonged pressure of a dorsally dislocated femoral head [3]. Even if the closed reduction of the dislocated femoral head is successful, maintaining the femoral head in a proper position is not always possible because of a fracture instability. These types of acetabular fractures associated with progressive sciatic nerve palsy should be considered as a surgical emergency [3]. These fractures should be stabilized by temporary fixation techniques like long-bone and pelvic fractures in severely injured patients. Skeletal traction is a common technique for temporary stabilization in clinical practice. Traction should not compromise pulmonary toilet [3], especially in a polytraumatic patient with chest trauma. Nursing management of a polytraumatized patient in an intensive care unit (ICU)
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with skeletal traction applied is not easy. The transport of the patient with applied traction to computed tomography (CT) or to a specialized center is problematic as well. Tile et al. [3] advocates that the patient should have nursing care as if no traction is present. Supracondylar traction is preferable. The trochanteric pin can be a cause of postoperative complications due to its location in the surgical approach area. External fixation (EF) is one of the mainstays of operative fracture treatment [10]. At our level I trauma center, we use it frequently for pelvic and femoral fractures in severely injured patients. In combination with pelvic with acetabular or proximal femoral fractures, we use the connection of both frames to span the affected hip joint. The final frame is a triangle shape. The indications are unstable acetabular fractures in polytraumatized patients, who are not able to undergo open reduction and internal fixation early after injury. The typical case is a polytraumatized patient with dislocation fracture associated with serious posterior instability (Fig. 1). But a problem occurs if the insertion of a Schanz screw is not possible in an injured hemipelvis due to comminution of the iliac bone and the
Crossover external fixator for acetabular fractures
Fig. 2 Creation of the fracture model documented by an image intensifier; a superior pubic rami osteotomy; b inferior pubic rami osteotomy; c osteotomy of iliac bone above the acetabular roof;
d creation of ‘‘floating acetabulum’’; e osteotomy dividing both acetabular columns; f dislocation of the acetabular fracture model
femoral head stays in a central dislocation position. Therefore, we tried to apply a crossover external fixator frame with anchorage only in the contralateral hemipelvis and ipsilateral femoral shaft in a few cases. Although our clinical experience has been good, the stabilization effect is unclear. Therefore, we decided to test the frame stability on human cadavers. The aim of this study is the biomechanical testing of a new crossover external fixator frame for acetabular fractures, based on the commonly used external fixator device. After the acetabular fracture model creation (type C2.2 according to the AO classification) on a human cadaver, the stability of this technique was tested. The stabilization effect was compared with stabilization by large distractor (LD), which represents one of the possible methods of lateral trochanteric traction.
according to the donation programme and legislation of the Czech Republic. This study was approved by the local Ethical Committee. Cadavers were preserved according to Thiel’s embalming method [11]. The left hip joint was used in each cadaver due to the autopsy room arrangement. First, model of the acetabular fracture type C2.2 (bothcolumn fracture) according to the AO classification [4] was made. Osteotomy of both pubic rami juxtasymphyseally and T-shaped acetabular osteotomy were made under image intensification via the Stoppa approach [12]. The osteotomies were performed by chisel and oscillating saw (Fig. 2). The typical central dislocation of the fracture and femoral head was done by a lateral press to the great trochanter after osteotomies. The size of summation of the vertical and horizontal displacements of the femoral head was more than 20 mm. The displacement in each cadaver was documented by X-ray. After the fracture model was created, reduction and stabilization of the fracture was performed. In each cadaver, the fracture was stabilized by a crossover frame of EF and by LD subsequently. In five cases (N1–N5), the fracture was stabilized by EF first and by LD afterwards. In the rest of the cadavers (N6–N10), the stabilization was done in reverse sequence due to the error of the reduction method.
Materials and methods Ten human cadavers (five males and five females) were used for this experiment. The mean age of the bodies was 66.3 years (range 56–72 years). The cadavers were persons who had donated their body to scientific research,
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Fig. 4 Cadaver with large distractor applied (the midline incision is due to creation of the fracture model via the Stoppa approach)
Fig. 3 Cadaver with crossover external fixation frame applied (front view, head at the top): no Schanz screw in the affected hemipelvis is placed (the midline incision is due to creation of the fracture model via the Stoppa approach)
Application of both EF and LD was performed under image intensifier control. The principles and technique of application were the same as in clinical practice [10]. In the EF technique, the large external fixator (Synthes, USA) was used (Fig. 3). The frame design was patterned on the clinical usage of the external fixator in pelvic surgery and biomechanical principles of EF. The intersection of the biischiadic line and left femoral shaft (ipsilateral according to the fracture) was found and a Schanz screw was inserted in this point in the sagittal plane. The next two Schanz screws were inserted in the same plane 6 and 12 cm distally in the femoral shaft. These three Schanz screws were connected by a tube. One more Schanz screw was inserted in the supraacetabular area close to the acetabular roof in the contralateral side (right side). Another screw was inserted in the iliac crest on the same side. These two Schanz screws were connected with a tube and a third Schanz screw was inserted through the clamp on the tube in the spina iliaca anterior inferior area. These two parts (femoral and pelvic) of the frame were connected by two tubes. After reduction under an image intensifier, the frame was locked. The hip joint was in 30° of flexion. The long spanning tubes were joined by two 5-mm rods (in thirds) due to increasing rotational stability (Fig. 3). In the LD stabilization technique, the large distractor (Synthes, USA) was used (Fig. 4). One Schanz screw was inserted in the ipsilateral femoral neck with firm anchorage in the Adam’s arch. The second screw was inserted in the
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ipsilateral supraacetabular region cranially to the fracture. The LD device was applied and reduction under image intensification was made by both limb manipulation and by a distraction device. After the stabilization was applied, manipulation with the cadaver was carried out. The manipulation was performed by three persons according to standard protocol. This protocol was set up by the authors and should be a simulation of manipulation with a polytraumatized patient in the first 48 h of intensive care unit stay, including transport to CT. The cadaver was turned to the lateral decubitus position on the uninjured side and back to the supine position five times. Afterwards, the cadaver was transferred to the patient trolley stretcher and back two times. After manipulation, the hip joint was X-rayed and the fixation device was removed. Repeated dislocation of the fracture was created and documented by X-ray and the second stabilization technique followed. Each step (dislocation–reduction–manipulation) of each technique was documented by a calibrated X-ray picture. The method of calibration and calculating the radiological magnification described by King et al. [13] was used. The X-ray pictures in DICOM format were evaluated by the superimposition technique. The position of the femoral head before and after manipulation was measured for each stabilization technique. Vertical and horizontal shifts of the femoral head were obtained. The total shift of the femoral head caused by manipulation was calculated. Statistical analysis was performed using the Statistica 9 software (StatSoft, USA). A Wilcoxon test for paired samples was used for the stabilization techniques comparison. Analysis of the impact of the stabilization technique sequence was carried out using the Mann–Whitney test. A p-value \0.05 was considered to be statistically significant for both analyses.
Crossover external fixator for acetabular fractures Table 1 Values of the horizontal, vertical and total shifts after manipulation, mean ± standard deviation (SD) Shift
External fixator (mm)
Large distractor (mm)
p-value
Horizontal
2.1 ± 1.73
4.4 ± 3.17
0.075
Vertical
0.7 ± 0.82
2.0 ± 2.31
0.074
2.56 ± 1.34
5.11 ± 3.52
0.066
Total
Table 2 Total femoral head shifts after manipulation (mm) Cadaver
Total shift (mm) External fixator
Large distractor
N1
4.1
4
N2
4
9.8
N3
2
4.5
N4
1
8.1
N5
1
2.2
N6
1.4
4.5
N7 N8
4 2
1 0
N9
4.1
7.1
N10
2
9.9
Results A model of acetabular fracture type C2.2 with the required dislocation was created in all cadavers (N1–N10). No complications occurred during fracture model creation. No significant differences were noted between the matched EF and LD values regarding the horizontal, vertical and total shifts of the femoral head (p [ 0.05). The values of all shifts along with the statistical analysis are presented in Table 1. The values of the total shifts of each cadaver are shown in Table 2. All values and measurements are presented at full proportions (mm) after calculation of the radiological magnification. For all three shifts (horizontal, vertical and total), the influence of the stabilization techniques sequence (N1–5 vs. N6–10 groups) was not significant (p [ 0.05). No complication such hardware loosening or breakage occurred during the experimental study.
Discussion Due to the complexity of acetabular fractures and their association with other injuries, it is difficult to define a clear universal algorithm for treatment. Open reduction and internal fixation is indicated for most types of fractures.
But its timing is determined by the fracture type and general condition of the patient. Matta suggested a timing of 48 h due to initial bony and venous bleeding reduction [14]. Tile et al. [3] advises to wait for 3–5 days. Katsoulis and Giannoudis [1] in their meta-analysis preferred definitive internal fixation performed after the fourth day, unless the patient’s condition forces the delay in surgery. In these algorithms, only the supracondylar or trochanteric skeletal traction are meant for the temporary stabilization technique [3]. Despite the fact that, in none of these algorithms an external fixation for acetabular fractures is mentioned, we used it successfully for a few cases. The external fixator was used for temporary fracture stabilization in all cases. The indication was either because of the acetabular fracture pattern or because of the polytraumatized patient’s management. The first group was patients with unstable or irreducible fracture patterns who were not able to undergo open reduction and internal fixation initially (Fig. 1). In these cases, the temporary stabilization by skeletal traction was not sufficient, contrary to external fixation. The second group was patients with acetabular fractures in which stabilization by skeletal traction was sufficient, but patients’ management (e.g. nursing care, repetitive transport to CT or angiography) was easier with an external fixator rather than skeletal traction applied. On the other hand, the fixator frame could interfere with laparotomy, like the frame applied for pelvic fractures. Frame design was patterned on the clinical usage of the external fixator in pelvic surgery and the biomechanical principles of external fixation. Easy application in clinical practice is important. External fixator frame application takes about 30 min under fluoroscopy control. The indications and contraindications of the external fixator for acetabular fractures have not yet been established in clinical practice. In the opinion of the authors, the indication is displaced unstable acetabular fracture mainly in polytraumatized patients. The contraindication is fracture of the areas where the fixator frame is anchored (contralateral iliac bone or ipsilateral femur). The areas of Schanz screws application are usually without soft tissue problems, because the frame is applied anteriorly. Therefore, Morel–Lavalle´e lesions (on both sides) is not a contraindication. This study has several weaknesses. One limitation is the number of cadavers. We chose cadavers embalmed by Thiel’s technique due to the flexibility of their tissues [11, 15]. Although we were not able to obtain more than ten cadavers, this number is still sufficient for statistical analysis. Similar cadaver studies have no more than 12 cadavers [16, 17]. The next problem is the imaging technique used for shift evaluation. We used plain X-ray in the frontal plane (A-P view) for checking the femoral head position. But a more important problem in clinical practice
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is the shift of the femoral head dorsally in the sagittal plane due to the instability of the fracture [3]. We know that a better and more accurate evaluation technique would be CT, but it was impossible to use under our conditions. Although the acetabular fracture type C2.2 is not a common both-column fracture in clinical practice, we chose it because of its easy creation with low risk of femoral head damage and possibility of large distractor anchorage to the ipsilateral iliac bone. We used a large distractor as a reference technique. Clinical usage of this reduction and stabilization technique is mainly intraoperatively [3]. This technique is equal to trochanteric traction, which can be used for temporary stabilization. In clinical practice, trochanteric traction is not recommended because the pin entry is in the area of subsequent surgical approach [3]. Another reason for supracondylar traction preference is frequent injury of the trochanteric area. Insertion of the pin into the Morel– Lavalle´e lesion is hazardous due to the high infection rate. Although we know that using supracondylar skeletal traction is a temporary stabilization technique in most clinical cases, we chose the large distractor because of equal stability and better standardization of the manipulating protocol. There is a problem with Schanz screws anchorage in osteoporotic pelvic bone. Despite the fact that this experiment was performed on elderly cadavers (mean age 66.3 years) and the osteoporosis could be expected, no hardware loosening occurred. In clinical practice, the crossover external fixator has the same risks as the external fixator for pelvic fractures in this type of patient [18], and early conversion for internal osteosynthesis is recommended. The crossover external fixation could be a suitable solution for temporary stabilization of acetabular fractures in polytraumatized patients. The crossover frame design does not conflict with the subsequent surgical approach for open reduction and internal fixation. Subsequent studies including clinical trials are necessary to confirm authors’ suggestion. Acknowledgments This study was financially supported by the Ministry of Defence of the Czech Republic (project no. OVUOFVZ200904). Conflict of interest On behalf of all authors, the corresponding author states that there is no conflict of interest.
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