Surgical management of osteoporotic pelvic fractures: a new challenge

Primary stability of three different iliosacral screw fixation techniques in osteoporotic cadaver specimens-a biomechanical investigation

BACKGROUND

The incidence of osteoporotic and insufficiency fractures of the pelvic ring is increasing. Closed reduction and percutaneous fixation with cannulated sacroiliac screws is well-established in the operative treatment of osteoporotic posterior pelvic ring fractures. However, osteoporotic bone quality might lead to the risk of screw loosening. For this reason, cement augmentation of the iliosacral screws is more frequently performed and recommended.

PURPOSE

The aim of the present biomechanical study was to evaluate the primary stability of three methods of iliosacral screw fixation in human osteoporotic sacrum specimens.

STUDY DESIGN/SETTING

This study used methodical cadaver study.

METHODS

A total of 15 fresh frozen human cadaveric specimens with osteoporosis were used (os sacrum). After matched pair randomization regarding bone quality (T-score), three operation technique groups were generated: screw fixation (cannulated screws) without cement augmentation (Group A); screw fixation with cement augmentation before screw placement (cannulated screws) (Group B); and screw fixation with perforated screws and cement augmentation after screw placement (Group C). In all specimens both sides of the os sacrum were used for operative treatment, resulting in a group size of 10 specimens per group. One operation technique was used on each side of the sacral bone to compare biomechanical properties in the same bone quality. Pull-out tests were performed with a rate of 6 mm/min. A load versus displacement curve was generated.

RESULTS

Subgroup 1 (Group A vs. Group B): Screw fixation without cement augmentation: 594.4 N±463.7 and screw fixation with cement augmentation before screw placement: 1,020.8 N±333.3; values were significantly different (p=.025). Subgroup 2 (Group A vs. Group C): Screw fixation without cement augmentation: 641.8 N±242.0 and perforated screw fixation with cement augmentation after screw placement: 1,029.6 N±326.5; values were significantly different (p=.048). Subgroup 3 (Group B vs. Group C): Screw fixation with cement augmentation before screw placement: 804.0 N±515.3 and perforated screw fixation with cement augmentation after screw placement: 889.8 N±503.3; values were not significantly different (p=.472).

CONCLUSIONS

Regarding iliosacral screw fixation in osteoporotic bone, the primary stability of techniques involving cement augmentation is significantly higher compared with screw fixation without cement augmentation. Perforated screws with the same primary stability as that of conventional screw fixation in combination with cement augmentation might be a promising alternative in reducing complications of cement leakage. These biomechanical results have to be transferred into clinical practice and prove their clinical value.

Osteoporotic Fracture: 2015 Position Statement of the Korean Society for Bone and Mineral Research

Osteoporotic fractures are one of the most common causes of disability and a major contributor to medical care costs worldwide. Prior osteoporotic fracture at any site is one of the strongest risk factors for a new fracture, which occurs very soon after the first fracture. Bone mineral density (BMD) scan, a conventional diagnostic tool for osteoporosis, has clear limitations in diagnosing osteoporotic fractures and identifying the risk of subsequent fractures. Therefore, early and accurate diagnosis of osteoporotic fractures using the clinical definition which is applicable practically and independent of BMD, is essential for preventing subsequent fractures and reducing the socioeconomic burden of these fractures. Fractures caused by low-level trauma equivalent to a fall from a standing height or less at major (hip, spine, distal radius, and proximal humerus) or minor (pelvis, sacrum, ribs, distal femur and humerus, and ankle) sites in adults over age 50, should be first regarded as osteoporotic. In addition, if osteoporotic fractures are strongly suspected on history and physical examination even though there are no positive findings on conventional X-rays, more advanced imaging techniques such as computed tomography, bone scan, and magnetic resonance imaging are necessary as soon as possible.

The role of angio-embolization in the acute treatment concept of severe pelvic ring injuries

BACKGROUND

In recent years a wide variety of strategies to treat the haemodynamically unstable patient with pelvic ring fractures have been proposed. This study evaluates our institutional management of patients with severe pelvic fractures and analyses their outcomes.

METHODS

Retrospective review of all severely injured trauma patients with pelvic ring injuries admitted to a level I trauma centre from 2007 to 2012. Patient records were documented prospectively in a trauma database and evaluation was performed by SPSS.

RESULTS

During the study period, a total of 173 patients with pelvic ring fractures were admitted and formed the basis of this study. Overall, 46% of the patients had suffered a type A fracture, 25% a type B fracture and the remaining 29% a type C pelvic ring fracture. Surgical treatment was required in 21% of the patients (pelvic C-clamp, n = 6; supra-acetabular external fixator, n = 32; pelvic packing, n = 12; definitive plate osteosynthesis of the pubis symphysis, n = 6). Angio-embolization was performed in 16 patients (9%); in 8 patients it was the only specific treatment for the pelvic injury on day 0 and in 8 patients it was performed immediately post-operatively. The overall mortality rate was 12.7% (n = 22), with the type C pelvic fractures having the highest mortality (30.0%). Four patients died immediately after admission in the shock room.

CONCLUSIONS

Angiographic embolization as a first-line treatment was only performed in haemodynamically stable patients or in patients responding to fluid resuscitation with the finding of an arterial blush in the CT scan. In haemodynamically unstable patients, pre-peritoneal pelvic packing in combination with mechanical pelvic stabilization was immediately carried out, followed by angio-embolization post-operatively if signs of persistent bleeding remained present.

[Implant augmentation in pelvic surgery. Options and technique]

BACKGROUND

Osteoporotic fractures of the pelvis are an increasing problem in trauma surgery. Sufficient implant anchorage is reduced due to the poor bone stock; however, early mobilization is especially necessary for geriatric patients in order to prevent additional complications.

MATERIAL AND METHODS

Implant augmentation may be one technique to increase implant anchorage and stability in osteoporotic bone. This procedure is currently used in the treatment of osteoporotic fractures of the dorsal pelvic ring. Beside the augmentation of iliosacral screws in the treatment of sacral insufficiency fractures, cement augmentation with lumbar or sacral pedicle screws is used for increased stability.

INDICATIONS AND RISKS

Implant augmentation in pelvic surgery should be indicated crucially due to the specific risks of the procedure. Cement leakage and heat generation during cement curing (when PMMA--polymethylmetacrylate--cement is used) can compromise neurovascular structures. Potential complications like cement embolism are possible.

CONCLUSION

The use of special implants (cannulated and perforated screws) as well as intraoperative navigation and 3D imaging increase patient safety and help to make implant augmentation a low risk procedure.

Assessment of the Breakaway Torque at the Posterior Pelvic Ring in Human Cadavers

Purpose: To enhance the diminished screw purchase in cancellous, osteoporotic bone following the fixation of posterior pelvic ring injuries by iliosacral screws an increased bone-implant contact area using modificated screws, techniques or bone cement may become necessary. The aim of the study was to identify sites within the pathway of iliosacral screws requiring modifications of the local bone or the design of instrumentations placed at this site. Materials and Methods: The breakaway torque was measured mechanically at the iliosacral joint (“ISJ”), the sacral lateral mass (“SLM”) and the center of the S1 (“CS1”), at a superior and an inferior site under fluoroscopic control on five human cadaveric specimens (3 female; mean age 87 years, range: 76–99) using the DensiProbe™Spine device. Results: The measured median (range) breakaway torque was 0.63 Nm (0.31–2.52) at the “iliosacral joint”, 0.14 Nm (0.05–1.22) at the “sacral lateral mass”, 0.57 Nm (0.05–1.42) at the “S1 center.” The “sacral lateral mass” breakaway torque was lower than compared to that at the “iliosacral joint” (p < .001) or “S1 center” (p < .001). The median (range) breakaway torque measured at all superior measurement points was 0.52 Nm (0.10–2.52), and 0.48 Nm (0.05–1.18) at all inferior sites. The observed difference was statistically significant (p < .05). Conclusions: The lateral mass of the sacrum provides the lowest bone quality for implant anchorage. Iliosacral screws should be placed as superior as safely possible, should bridge the iliosacral joint and may allow for cement application at the lateral mass of the sacrum through perforations.

Fragility fractures of the pelvis: treatment and preliminary results

BACKGROUND

With increasing life expectancy, fragility fractures of the pelvic ring (FFP) are becoming frequent. In elderly, osteoporosis leads to a decrease of bone strength and resistance to the ligament's traction; this represents the most important difference between FFP and fractures in young patients. Usually, these fractures are underestimated and treatment is often conservative.

AIMS

To evaluate clinical and surgical outcomes of surgically treated patients with FFP.

METHODS

We retrospectively enrolled 14 patients, in our Trauma Center, underwent surgery procedures for FFP between 2012 and 2014. All patients attended clinical and radiological investigation at 1, 3, and 6 months postoperatively and every year after surgery with a mean follow-up of 22 months.

RESULTS

At 6-month follow-up, 11 patients resulted asymptomatic: able to maintain standing position and walk without crunches. Two patients were able to walk with one crunch. The patient with history of previous acetabular fracture walks with two crunches and is still waiting for total hip arthroplasty.

DISCUSSION

The compromised health status and the diminished bone-healing capacity, in elderly, decrease chances for a good clinical outcome. In literature, many authors suggest that mortality rate in patients with FFP is similar to those with hip fracture. Diagnosis of FFP is very important: these fractures are highly disabling in elderly and can lead to displacement and instability. For these reasons, correct diagnosis and well-conduct preoperative plan are necessary to improve stability of fractures and support bone healing. After diagnosis, an anti-osteoporotic treatment is indicated to improve bone quality and bone healing.

CONCLUSIONS

Our study shows encouraging results and demonstrates that minimally or less invasive osteosynthesis technique could lead to good outcome in these patients.

A biomechanical study of standard posterior pelvic ring fixation versus a posterior pedicle screw construct

OBJECTIVES

The purpose of this study was to biomechanically test a percutaneous pedicle screw construct for posterior pelvic stabilisation and compare it to standard fixation modalities.

METHODS

Utilizing a sacral fracture and sacroiliac (SI) joint disruption model, we tested 4 constructs in single-leg stance: an S1 sacroiliac screw, S1 and S2 screws, the pedicle screw construct, and the pedicle screw construct+S1 screw. We recorded displacement at the pubic symphysis and SI joint using high-speed video. Axial stiffness was also calculated. Values were compared using a 2-way ANOVA with Bonferroni adjustment (p<0.05).

RESULTS

In the sacral fracture model, the stiffness was greatest for the pedicle screw+S1 construct (p<0.001). There was no significant difference between the pedicle screw construct and S1 sacroiliac screw (p=1). For the SI joint model, the S1+S2 SI screws had the largest overall load and stiffness (p<0.001). The S1 screw was significantly stronger than pedicle screw construct (p=0.001).

CONCLUSIONS

The pedicle screw construct biomechanically compares to currently accepted methods of fixation for sacral fractures when the fracture is uncompressible. It should not be used for SI joint disruptions as one SI or an S1+S2 are significantly stiffer and cheaper.

Percutaneous iliosacral screw fixation after osteoporotic posterior ring fractures of the pelvis reduces pain significantly in elderly patients

INTRODUCTION

Osteoporotic posterior ring fractures of the pelvis are common injuries in the elderly, but the treatment of these fractures still remains controversial. Percutaneous iliosacral screw fixation is one surgical option if conservative treatment cannot provide sufficient pain reduction. The aim of this study is to provide short-term results of elderly patients with percutaneous screw fixation.

METHODS

30 patients with posterior ring fractures were treated between 12/2009 and 01/2014 with percutaneous iliosacral screw fixation. Patients' mean age was 78.4 years. Concerning short-term outcome, we focused on initial pain level and postoperative pain reduction together with intra- and postoperative complications.

RESULTS

The average hospital stay was 23.7 days, with surgical treatment performed after an average of 9.2 days. 90% of our patients were female. All 30 patients had a lower level of pain at discharge compared with admission or immediately prior to surgery. The difference in pain level at admission compared with the pain level upon discharge showed a mean reduction from 6.8 to 1.8 with a statistically significant change (P≤0.001). 24 of 30 patients had no registered complications, one screw malpositioning with postoperative nerve irritation occurred.

DISCUSSION

Conventional percutaneous iliosacral screw fixation is a successful operative treatment for elderly patients with persistent lower back pain after unstable posterior ring fractures of the pelvis. Intra- and postoperative complications are rare, so this treatment can be regarded as a safe procedure.

LEVEL OF EVIDENCE

IV (retrospective study).

Fragility fractures of the sacrum: how to identify and when to treat surgically?

The increasing prevalence of fragility fractures of the sacrum (FFS) occurring predominantly in osteoporotic individuals poses a diagnostic and therapeutic challenge. The clinical presentation varies from longstanding low back pain without the patient remembering a traumatic event to immobilized patients after suffering a low-energy trauma. FFS are often combined with a fracture of the anterior pelvic ring; hence they are classified as a part of fragility fractures of the pelvis (FFP). If not displaced, the patients are treated with weight bearing as tolerated and analgesics; however, we advocate to treat displaced fractures surgically according to the fracture personality and the patient’s comorbidities. Surgical options include minimal invasive sacro-iliac screws, trans-sacral bar osteosynthesis, open reduction and internal fixation, or spinopelvic stabilization. In the light of the high complication rate associated with immobilized patients, an operative approach often is indicated to accelerate the patient’s mobility.

Bilateral nonunion of the sacrum in a long-term paraplegic patient treated with trans-sacral bar and spinopelvic fixation

The incidence of fragility fractures of the pelvis is sharply increasing in accordance with growing life expectancy in developed countries. Numerous conditions may compromise bone density and quality, and paraplegia due to spinal cord injury is one of them. As screw anchorage is often problematic in poor bone stock, spinopelvic dissociation demands a type of osteosynthesis, which is less dependent on the density of trabecular bone. We present a case of a paraplegic 45-year-old man, with non-displaced bilateral nonunion of the sacrum. The patient was treated with trans-sacral bar and spinopelvic fixation. Rapid relief from pain and functional recovery was achieved with complete bone healing 1 year after the operation.

Significance of clinical examination, CT and MRI scan in the diagnosis of posterior pelvic ring fractures

INTRODUCTION

Patients with a fracture in the anterior pelvic ring often simultaneously demonstrate pain in the posterior pelvic ring. The aim of the present prospective study was to assess the sensitivity of CT, MRI and clinical examination in the detection of fractures in the posterior pelvic ring in patients with fractures of the anterior pelvic ring diagnosed in conventional radiographs.

METHODS

Sixty patients with radiographic signs of an anterior pelvic ring injury were included in this prospective analysis. Following a focused clinical examination of the posterior pelvis, all patients underwent both a CT and then a MRI scan of their pelvis. Two board certified radiologists evaluated the CT and MRI scans independently. To estimate the presence of osteoporosis the Hounsfield units of the vertebral body of L5 were measured in each case.

RESULTS

Fifty-three women and seven men, with a mean age of 74.7+/-15.6 years were included into the study. A fracture of the posterior pelvic ring was found in fourty-eight patients (80%) patients using MRI. Fractures of the posterior pelvic ring would have been missed in eight cases (17%), if only CT had been used. Eighty-five percent of the patients with a posterior fracture had an osteoporosis. The majority of the cases suffered from a low energy trauma. Thirty-eight patients (83%) with positive clinical signs at the posterior pelvic ring actually had a fracture of the posterior pelvic ring in the MRI. The clinical examination proved to be equally effective to CT in detecting posterior pelvic ring fractures.

CONCLUSION

The significance of both, clinical examination and CT was confirmed in the detection of fractures in the posterior pelvic ring. MRI examination of the pelvis however, was found to be superior in detecting undislocated fractures in a cohort of patients with a high incidence of osteoporosis. Using MRI may be beneficial in select cases, especially when reduced bone density is suspected.

Axial view of acetabular anterior column: a new X-ray projection of percutaneous screw placement

INTRODUCTION

To search for a new radiographic view/projection of the acetabular anterior column to provide a safe guide for percutaneous screw placement for acetabular fractures.

MATERIALS AND METHODS

Eight pelvic specimens taken from normal adult cadavers were positioned in a supine position on the operating table. First, the ipsilateral ilium-oblique view of the observed side was obtained on C-arm fluoroscopy by tilting the C-arm approximately 35° toward the contralateral hip joint. Then, the tilting angle of the C-arm was changed gradually until an oval track image (acetabular anterior column axial view) appeared. The oval shadow was clear only in one position as the angle of the C-arm was changed toward the caudal side of the operating table. A guide pin was put on the skin of the cadaver, and the location and tilting direction of the guide pin were adjusted under C-arm fluoroscopy until the pin's shadow became a point in the center of the oval track. Then, the guide pin was inserted into the bone using a battery-powered drill. The degree of inclination of the guide pin in the cadaver in the frontal and sagittal planes was measured using computed tomography (CT).

RESULTS

Axial views of the anterior column were found successfully in all of the pelvic specimens, and the guide pins were inserted accurately into the acetabular anterior column under C-arm fluoroscopic guidance. On the CT-reconstructed image, the average degree of angle between the guide pin and the sagittal plane was 33.6° (range 29.6°-36.5°). The average angle between the guide pin and the transverse plane was 59.1° (range 56.4°-63.2°).

CONCLUSION

This axial view of the acetabular anterior column is a novel X-ray projection which provides an optimal method for guiding percutaneous insertion of anterior column screws for acetabular fractures.

The Role of Pelvic Packing for Hemodynamically Unstable Pelvic Ring Injuries

In patients with severe pelvic fractures, exsanguinating hemorrhage represents the major cause of death within the first 24 hours. Recently, multiple management algorithms have been proposed; however, the optimal treatment modalities, in particular, in the hemodynamically unstable patient with pelvic fracture are still a matter of debate. Mechanical pelvic stabilization by pelvic binder, anterior external fixator, and/or pelvic C-clamp constitutes the first treatment option in the hemodynamically unstable patient with pelvic fractures. The mechanically stabilized pelvic ring provides the basis for pelvic packing through a minimal extraperitoneal approach, which effectively controls venous bleeding and bleeding from the fractured bony surface. Patients with persistent hypotension and/or transfusion requirements should undergo angiography and selective embolization for definitive arterial control if necessary. This review article describes the current trend in the initial management of patients with pelvic fractures and hemodynamic instability, and focuses on the role of pelvic packing.

Clinical pathways for fragility fractures of the pelvic ring: personal experience and review of the literature

Fragility fractures of the pelvic ring (FFP) are increasing in frequency and require challenging treatment. A new comprehensive classification considers both fracture morphology and degree of instability. The classification system also provides recommendations for type and invasiveness of treatment. In this article, a literature review of treatment alternatives is presented and compared with our own experiences. Whereas FFP Type I lesions can be treated conservatively, FFP Types III and IV require surgical treatment. For FFP Type II lessions, percutaneous fixation techniques should be considered after a trial of conservative treatment. FFP Type III lesions need open reduction and internal fixation, whereas FFP Type IV lesions require bilateral fixation. The respective advantages and limitations of dorsal (sacroiliac screw fixation, sacroplasty, bridging plate fixation, transsacral positioning bar placement, angular stable plate) and anterior (external fixation, angular stable plate fixation, retrograde transpubic screw fixation) pelvic fixations are described.

3D statistical modeling techniques to investigate the anatomy of the sacrum, its bone mass distribution, and the trans-sacral corridors

The complex anatomy of the sacrum makes surgical fracture fixation challenging. We developed statistical models to investigate sacral anatomy with special regard to trans-sacral implant fixation. We used computed tomographies of 20 intact adult pelves to establish 3D statistical models: a surface model of the sacrum and the trans-sacral corridor S1, including principal component analysis (PCA), and an averaged gray value model of the sacrum given in Hounsfield Units. PCA demonstrated large variability in sacral anatomy markedly affecting the diameters of the trans-sacral corridors. The configuration of the sacral alae and the vertical position of the auricular surfaces were important determinants of the trans-sacral corridor dimension on level S1. The statistical model of trans-sacral corridor S1 including the adjacent parts of the iliac bones showed main variation in length; however, the diameter was the main criterion for the surgically available corridor. The averaged gray value model revealed a distinct pattern of bone mass distribution with lower density particularly in the sacral alae. These advanced 3D statistical models provide a thorough anatomical understanding demonstrating the impact of sacral anatomy on positioning trans-sacral implants.

Crossover external fixator for acetabular fractures: a cadaver study

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 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.

Posterior iliac crescent fracture-dislocation: is it only rotationally unstable?

Posterior iliac crescent fracture-dislocation is generally considered rotationally unstable and vertically stable. The current study (1) investigated whether vertical instability may occur in posterior iliac crescent fracture-dislocation and (2) analyzed the clinical features of vertically unstable iliac crescent fracture-dislocation as well as treatment strategies. Patients with pelvic fracture who were treated in the authors' department from June 2009 to June 2012 were retrospectively reviewed. This study analyzed the clinical features, including incidence, hemodynamic state, associated injuries, injury severity score, and treatment methods for vertically unstable iliac crescent fracture-dislocation. Four patients had vertically unstable fracture-dislocation, accounting for 12.9% of all iliac crescent fracture-dislocations. All 4 patients were hemodynamically unstable on admission and had complications of associated injuries with a higher injury severity score. In 3 of the 4 patients, iliac crescent fracture-dislocations were reduced via the posterior approach at the initial stage and these patients underwent fixation with a plate. The remaining patient was initially given transcondylar traction because of severe complications and underwent open reduction and internal fixation (ORIF) via a posterior approach at a later stage. The outcomes of all 4 patients were rated as good or excellent by the Kobbe rating system at the last follow-up. Vertical instability may occur in iliac crescent fracture-dislocation. The authors propose ORIF of the fracture-dislocation via a posterior approach. When initial surgery is not possible because of severe associated organ injuries, the authors propose transcondylar traction to allow reduction of the sacroiliac joint and ORIF at a later stage.

Osteoporotic pelvic ring injuries

As with most fractures associated with osteoporosis, the incidence of pelvic ring injuries in this population of patients is rising rapidly. Osteoporotic pelvic ring injuries are exceedingly different in their etiology, natural history, and treatment from the more recognizable patterns in young patients with high-energy pelvic ring injuries. Recognition of a potentially unstable fracture pattern, careful evaluation of the ambulatory and functional status of each patient before injury, and the potential pitfalls and benefits of operative versus nonoperative care are critical to the effective treatment.

[Selection of access and positioning for operative treatment of pelvic injuries. Decision-making strategies]

Surgical treatment of pelvic ring injuries requires in-depth knowledge of the topographic anatomy of the pelvic bones, joints and soft tissue structures. A wide range of stabilizing techniques is available including bridging plate osteosynthesis, iliosacral compression screw osteosynthesis and transpubic positioning screws. In this article the different treatment strategies with the respective surgical approaches and patient positioning for pelvic ring fractures and combined lesions of the pelvic ring and acetabulum are presented. Pelvic ring lesions with rotational instability are approached from the anterior and occasionally from both the anterior and posterior based on the amount and localization of the instability. In vertically unstable lesions the most unstable part must be addressed first by reduction and fixation of the dislocated part to the axial skeleton. In combined fractures of the pelvis and acetabulum dorsal stabilization is carried out first.