A Comprehensive Analysis With Minimum 1-Year Follow-up of Vertically Unstable Transforaminal Sacral Fractures Treated With Triangular Osteosynthesis

Orthopaedic Trauma Service, Florida Orthopaedic Institute, Tampa, FL 33606, USA.
Journal of orthopaedic trauma (Impact Factor: 1.8). 05/2009; 23(5):313-9; discussion 319-21. DOI: 10.1097/BOT.0b013e3181a32b91
Source: PubMed


To analyze the radiographic, clinical, and functional results of triangular osteosynthesis constructs for the treatment of vertically unstable comminuted transforaminal sacral fractures.
Level I trauma center.
During a 3-year period (July 1, 2003 to June 30, 2006), 58 patients with vertically unstable pelvic injuries were treated with triangular osteosynthesis fixation by a single surgeon at a single institution. Patients were followed-up prospectively as a single cohort, with institutional review board approval. Inclusion criteria for this study were skeletally mature patients with a vertically unstable pelvic ring injury associated with a comminuted transforaminal sacral fracture. Minimum follow-up, both clinically and radiographically, was 1 year. Computed tomography scan was performed on all patients at 6 months to assess healing of the fracture. If the fracture healed, the fixation was removed. Functional outcome was assessed using the Short Form 36, version 2, and short version of Musculoskeletal Functional Assessment questionnaires at 6 months (before fixation removal) and 12 months.
Forty of 58 patients with an average age of 39 years were available for a minimum of 1-year follow-up. Wound complications requiring surgical debridement occurred in 5 patients (13%), all of whom had severe soft tissue wounds with internal degloving. Two patients required removal of infected fixation. Iatrogenic L5 nerve injury occurred in 5 patients (13%). Ten patients (25%) had a delayed union on computed tomography scans, and 3 patients had a nonunion as a result of residual fracture gap and incomplete reduction. Six patients (15%) were found to have pronounced tilting of the L5 vertebral body (scoliosis) and distraction of the L5/S1 facet joint ipsilateral to the fixation. This did not correct with removal of the fixation. Failure of the triangular osteosynthesis construct resulting in malunion occurred in 2 patients (5%). All but 2 patients (95%) complained of painful and prominent implants. Functional outcome scoring showed that patients continued to function below the population mean at 1 year but continued to improve, particularly with function and daily activity. Ninety-seven percent of patients returned to some form of work or schooling.
Triangular osteosynthesis fixation is a reliable form of fixation that allows early full weight-bearing at 6 weeks while preventing loss of reduction in comminuted vertical shear transforaminal sacral fractures. For this study group, operative reduction was maintained until healing in 95% of patients. However, the 1-year follow-up shows a substantial rate of potential technical problems and complications. Of primary concern were the asymmetric L5 tilting with L5-S1 facet joint distraction and the need for a second surgery in all patients to remove painful fixation. Iatrogenic nerve injury occurred in 5 patients (13%) and is thought to arise secondary to fracture manipulation and reduction. We recommend selective use of this technique for comminuted transforaminal sacral fractures in situations only where reliable iliosacral or trans-sacral screw fixation is not obtainable.

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    • "In a biomechanical study, triangular osteosynthesis was shown to be superior to iliosacral screws alone for fixation of unstable transforaminal sacral fractures.13 Sagi et al.14 reported on the use of triangular osteosynthesis in 58 patients with vertically unstable transforaminal sacral fractures. Patients were allowed full weight bearing at 6 weeks, with only a 5% malunion rate. "
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    ABSTRACT: The treatment algorithm for sacral fracture associated with vertical shear pelvic fracture has not emerged. Our aim was to study a new approach of fixation for comminuted and vertically unstable fracture pattern with spinopelvic dissociation to overcome inconsistent outcome and avoid complications associated with fixations. We propose fixation with well-contoured thick reconstruction plate spreading across sacrum from one iliac bone to another with fixation points in iliac wing, sacral ala and sacral pedicle on either side. Present biomechanical study tests the four fixation pattern to compare their stiffness to vertical compressive forces. Dissection was performed on human cadavers through posterior midline paraspinal approach elevating erector spinae from insertion with two flaps. Feasibility of surgical exposure and placement of contoured plate for fixation was evaluated. Ten age and sex matched computed tomography scans of pelvis with both hips were obtained. Reconstructions were performed with advantage windows 4.2 (GE Light Speed QX/I, General Electric, Milwaukee, WI, USA). Using the annotation tools, direct digital CT measurement (0.6 mm increments) of three linear parameters was carried out. Readings were recorded at S2 sacral level. Pelvic CT scans were extensively studied for entry point, trajectory and estimated length for screw placement in S2 pedicle, sacral ala and iliac wing. Readings were recorded for desired angulation of screw in iliac wing ala of sacrum and sacral pedicle with respect to midline. The readings were analyzed by the values of mean and standard deviation. Biomechanical efficacy of fixation methods was studied separately on synthetic bone. Four fixation patterns given below were tested to compare their stiffness to vertical compressive forces: 1) Single S1 iliosacral screw (7.5 mm cancellous screw), 2) Two S1 and S2 iliosacral screws, 3) Isolated trans-iliosacral plate, 4) Trans-iliosacral plate + single S1 iliosacral screw. Mean of desired angulation for inserting screws and percentage of displacement on biomechanical testing was evaluated. Mean angulations for inserting sacral pedicel were 12.3° (SD 2.7°) convergent to midline and divergent of 14° (SD 2.3°) for sacral ala screw and 23° (SD 4.9°) for iliac wing screw. All screws needed to be inserted at an angle of 90° to sacral dorsum to avoid violation of root canals. Cross headed displacement across fracture site was measured and plotted against the applied vertical shear load of 300 N in five cycles each for all the four configurations. Also, the force required for cross headed displacement of 2.5 mm and 5 mm was recorded for all configurations. Transmitted load across both ischial tuberosities was measured to resolve unequal distribution of forces. Taking one screw construct (configuration 1) as standard base reference, trans-iliosacral plate construct (configuration 3) showed equal rigidity to standard reference. Two screw construct (configuration 2) was 12% stronger and trans-iliosacral plate (configuration 4) with screw was 9% stronger at 2.5 mm displacing on 300 N force, while it showed 30% and 6%, respectively, at 5 mm cross-headed displacement. Trans-iliosacral plating is feasible anatomically, biomechanically and radiologically for sacral fractures associated with vertical shear pelvic fractures. Low profile of plate reduces the risk of hardware prominence and decreases the need for implant removal. Also, the fixation pattern of plate allows to spare mobile lumbosacral junction which is an important segment for spinal mobility. Biomechanical studies revealed that rigidity offered by plate for cross headed displacement across fracture site is equal to sacroiliac screws and further rigidity of construct can be increased with addition of one more screw. There is need for precountered thicker plate in future.
    Full-text · Article · May 2012 · Indian Journal of Orthopaedics
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    ABSTRACT: Vertically unstable pelvic ring injuries associated with comminuted transforaminal sacral fractures present a special problem to the treating surgeon in applying stable fixation for maintaining reduction. Triangular osteosynthesis and spinal-pelvic constructs are relatively new techniques used to avoid loss of reduction for treating these difficult fractures, and the last decade has seen a marked increase in the use of these techniques. This article aims to describe the indications and technical aspects in the use of spinal-pelvic constructs for vertical shear sacral fractures such that they can be applied to better help the patients with these injuries.
    No preview · Article · May 2009 · Journal of orthopaedic trauma
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    ABSTRACT: Sacral fractures are commonly associated with pelvic ring fractures due to high-energy mechanisms of injury. An understanding of the anatomic relation of the sacrum to the lumbar spine, pelvis, and surrounding neurovascular structures is critical in evaluating functional deficits that may be associated with sacral fractures. While displaced fractures can be easily diagnosed on high quality plain radiographs, nondisplaced or transverse fracture patterns may be difficult to diagnose without a computed tomography scan. Once identified, correct classification of a sacral fracture can facilitate ideal treatment strategies. Stable nondisplaced fractures are usually treated nonoperatively, while significantly displaced fractures require reduction and internal fixation. Surgical fixation techniques include percutaneously placed iliosacral screws, posterior sacral "tension band" fixation, and for certain fracture patterns osteosynthesis that incorporates the lower lumbar spine (lumbopelvic or triangular fixation). This article reviews the approach to sacral fracture diagnosis and management.
    Full-text · Article · Oct 2009 · Orthopedics
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