Bone Cement Augmentation Research Articles

Does Cement Augmentation of the Sacroiliac Screw Lead to Superior Biomechanical Results for Fixation of the Posterior Pelvic Ring? A Biomechanical Study.

Background and Objectives: The stability of the pelvic ring mainly depends on the integrity of its posterior part. Percutaneous sacroiliac (SI) screws are widely implanted as standard of care treatment. The main risk factors for their fixation failure are related to vertical shear or transforaminal sacral fractures. The aim of this study was to compare the biomechanical performance of fixations using one (Group 1) or two (Group 2) standard SI screws versus one SI screw with bone cement augmentation (Group 3). Materials and Methods: Unstable fractures of the pelvic ring (AO/OTA 61-C1.3, FFP IIc) were simulated in 21 artificial pelvises by means of vertical osteotomies in the ipsilateral anterior and posterior pelvic ring. A supra-acetabular external fixator was applied to address the anterior fracture. All specimens were tested under progressively increasing cyclic loading until failure, with monitoring by means of motion tracking. Fracture site displacement and cycles to failure were evaluated. Results: Fracture displacement after 500 cycles was lowest in Group 3 (0.76 cm [0.30] (median [interquartile range, IQR])) followed by Group 1 (1.42 cm, [0.21]) and Group 2 (1.42 cm [1.66]), with significant differences between Groups 1 and 3, p = 0.04. Fracture displacement after 1000 cycles was significantly lower in Group 3 (1.15 cm [0.37]) compared to both Group 1 (2.19 cm [2.39]) and Group 2 (2.23 cm [3.65]), p ≤ 0.04. Cycles to failure (Group 1: 3930 ± 890 (mean ± standard deviation), Group 2: 3676 ± 348, Group 3: 3764 ± 645) did not differ significantly between the groups, p = 0.79. Conclusions: In our biomechanical setup cement augmentation of one SI screw resulted in significantly less displacement compared to the use of one or two SI screws. However, the number of cycles to failure was not significantly different between the groups. Cement augmentation of one SI screw seems to be a useful treatment option for posterior pelvic ring fixation, especially in osteoporotic bone.

Biomechanical analysis of recently released cephalomedullary nails for trochanteric femoral fracture fixation in a human cadaveric model.

Recently, two novel concepts for intramedullary nailing of trochanteric fractures using a helical blade or interlocking dualscrews have demonstrated advantages as compared to standard single-screw systems. However, these two concepts have not been subjected to a direct biomechanical comparison so far. The aims of this study were to investigate in a human cadaveric model with low bone quality (1) the biomechanical competence of nailing with the use of a helical blade versus interlocking screws, and (2) the effect of cement augmentation on the fixation strength of the helical blade. Twelve osteoporotic and osteopenic human cadaveric femoral pairs were assigned for pairwise implantation using either a short TFN-ADVANCED Proximal Femoral Nailing System (TFNA) with a helical blade head element or a short TRIGEN INTERTAN Intertrochanteric Antegrade Nail (InterTAN) with interlocking screws. Six osteoporotic femora, implanted with TFNA, were augmented with bone cement. Four groups were created: group 1 (TFNA) paired with group 2 (InterTAN), both consisting of osteopenic specimens, and group 3 (TFNA augmented) paired with group 4 (InterTAN), both consisting of osteoporotic specimens. An unstable trochanteric AO/OTA 31-A2.2 fracture was simulated and all specimens were tested until failure under progressively increasing cyclic loading. Stiffness in group 3 was significantly higher versus group 4, p = 0.03. Varus (°)and femoral head rotation around the femoral neck axis (°) after 10,000 cycles were 1.9 ± 1.0/0.3 ± 0.2 in group 1, 2.2 ± 0.7/0.7 ± 0.4 in group 2, 1.5 ± 1.3/0.3 ± 0.2 in group 3 and 3.5 ± 2.8/0.9 ± 0.6 in group 4, being significantly different between groups 3 and 4, p = 0.04. Cycles to failure and failure load (N) at 5° varus or10° femoral head rotation around the neck axisin groups 1-4 were 21,428 ± 6020/1571.4 ± 301.0, 20,611 ± 7453/1530.6 ± 372.7, 21,739 ± 4248/1587.0 ± 212.4 and 18,622 ± 6733/1431.1 ± 336.7, being significantly different between groups 3 and 4, p = 0.04. Nailing of trochanteric femoral fractures with use of helical blades is comparable to interlocking dualscrews fixation in femoral head fragments with low bone quality. Bone cement augmentation of helical blades provides significantly greater fixation strength compared to interlocking screws constructs.

Impact of Bone Cement Augmentation on the Fixation Strength of TFNA Blades and Screws.

Background and Objectives: Hip fractures constitute the most debilitating complication of osteoporosis with steadily increasing incidences in the aging population. Their intramedullary nailing can be challenging because of poor anchorage in the osteoporotic femoral head. Cement augmentation of Proximal Femoral Nail Antirotation (PFNA) blades demonstrated promising results by enhancing cut-out resistance in proximal femoral fractures. The aim of this study was to assess the impact of augmentation on the fixation strength of TFN-ADVANCEDTM Proximal Femoral Nailing System (TFNA) blades and screws within the femoral head and compare its effect when they are implanted in centre or anteroposterior off-centre position. Materials and Methods: Eight groups were formed out of 96 polyurethane low-density foam specimens simulating isolated femoral heads with poor bone quality. The specimens in each group were implanted with either non-augmented or cement-augmented TFNA blades or screws in centre or anteroposterior off-centre positions, 7 mm anterior or posterior. Mechanical testing was performed under progressively increasing cyclic loading until failure, in setup simulating an unstable pertrochanteric fracture with a lack of posteromedial support and load sharing at the fracture gap. Varus-valgus and head rotation angles were monitored. A varus collapse of 5° or 10° head rotation was defined as a clinically relevant failure. Results: Failure load (N) for specimens with augmented TFNA head elements (screw/blade centre: 3799 ± 326/3228 ± 478; screw/blade off-centre: 2680 ± 182/2591 ± 244) was significantly higher compared with respective non-augmented specimens (screw/blade centre: 1593 ± 120/1489 ± 41; screw/blade off-centre: 515 ± 73/1018 ± 48), p < 0.001. For both non-augmented and augmented specimens failure load in the centre position was significantly higher compared with the respective off-centre positions, regardless of the head element type, p < 0.001. Augmented off-centre TFNA head elements had significantly higher failure load compared with non-augmented centrally placed implants, p < 0.001. Conclusions: Cement augmentation clearly enhances the fixation stability of TFNA blades and screws. Non-augmented blades outperformed screws in the anteroposterior off-centre position. Positioning of TFNA blades in the femoral head is more forgiving than TFNA screws in terms of failure load.

Double plating - surgical technique and good clinical results in complex and highly unstable proximal humeral fractures

IntroductionA stable fixation of highly unstable proximal humerus fractures remains challenging and complication rates, especially secondary varus dislocation, remains high. Different techniques of double plate osteosynthesis have been suggested for the treatment of complex proximal humeral fractures as they are well established for other fractures. The aim of this study was to evaluate an operative technique using an angular stable lateral plate supported by a one-third tubular plate positioned anteriorly at the lesser tuberosity for unstable proximal humeral fractures. Patients and methodsRetrospectively, patients treated with a double plate osteosynthesis were included between January 2014 and December 2017. Out of 31, 25 patients (80.6%) with an average age of 53.1 years ± 12.5 were available for follow-up. 60% of the patients were male. The clinical evaluation consisted of a physical examination and standardised questionnaire including subjective and objective shoulder scores like the Constant-Murley Shoulder Score, Simple Shoulder Score, and Subjective Shoulder Value. ResultsAfter a mean follow-up of 30.9 months (range, 12-76 months) eighteen patients (72%) had either excellent or good results regarding the Constant-Murley Shoulder Score with a mean value of 77 points ± 17. Average Simple Shoulder Score was 76% ± 0.2 and Subjective Shoulder Value 72% ± 0.2%. Mean NSA at time of follow-up 135° ± 13°. Nine patients had an implant-removal, five in combination with arthrolysis after a mean of 7.2 months. Three patients underwent surgery for secondary arthroplasty. The study shows a complication rate of 16%. No revision-surgery because of secondary varus dislocation was reported. DiscussionArthroplasty is the less favourable treatment for a younger, active cohort of patients with highly unstable proximal humeral fractures as results are not as good and options for revision are limited. Double plate osteosynthesis can be used in addition to calcar screws, bone graft augmentation, cement augmentation and additional free screws for more multidirectional stability and shows good clinical results despite a higher rate of avascular necrosis and high primary stability with comparable complication-rates to single plate osteosynthesis. It seems to be a valid alternative to primary fracture arthroplasty and can prevent secondary varus displacement.

Clinicopathological and prognostic characteristics of acral metastases in patients with malignant disease: A retrospective study.

This study aimed to investigate the clinical, pathological, and prognostic characteristics of acral metastases in patients with malignant disease and to determine the impact of different types of acral metastasis treatment on patient survival. In this retrospective study, 64 acral metastatic lesions in 46 patients (17 women, 29 men; mean age, 61.5 years; age range, 35-82 years) who were evaluated by the Bone and Soft Tissue Tumors Council of our institute from 2015 to 2019 were included. The patients' primary tumor site, tumor type, localization of acral metastases, main symptom, duration from the diagnosis of the primary tumor to the diagnosis of acral metastasis, duration from the diagnosis of acral metastasis to death, and survival data were analyzed. The diagnosis of acral metastasis was confirmed by histopathological evaluation in 38 patients and clinical and radiological assessment of the lesions in 8 patients. The treatment type for each acral metastasis was individualized by the institutional Bone and Soft Tissue Tumors Council and categorized into 3 groups: excisional surgery (amputations and resections), palliative surgery (prophylactic fixation, intralesional curettage, and bone cement augmentation), and non-surgical treatment (chemotherapy, radiotherapy, and hormone therapy). A total of 16 acral metastases (25%) were identified in the upper extremity and 48 (75%) in the lower extremity. The most common primary tumor site was the lungs (32.6%), and the most common tumor type was adenocarcinoma (43.2%). The most frequent symptom and the primary reason for admission was pain (58.7%). The mean duration between the diagnosis of primary tumor and the diagnosis of acral metastasis was 19.1 (range, 0-124) months. No significant correlation was determined between the primary tumor types and duration from the diagnosis of primary tumor to the diagnosis of acral metastasis (p=0.278). Acral metastases were treated by excisional surgery in 15 (32.6%) patients, palliative surgery combined with non-surgical treatment in 10 (21.7%) patients, and only non-surgical treatment modalities in 21 (45.7%) patients. No significant correlation existed between the treatment types and patient survival (p=0.058). At the final follow-up, 30 (65.2%) patients were dead owing to the disease. The mean overall survival of the entire study group was 24.9 (range, 3-55) months. The mean duration between the diagnosis of acral metastasis and death was 7.6 (range, 3-24) months in patients who were dead owing to the disease (p=0.012). When the diagnosis of acral metastasis is established, it should be borne in mind that the most common primary tumor site and type are most likely the lungs and adenocarcinoma, respectively. The treatment type for acral metastasis may have no significant impact on patient survival, but the extensiveness of the disease may be a critical factor for survival. Level IV, Prognostic study.

Bone cement augmentation of femoral nail head elements increases their cut-out resistance in poor bone quality– A biomechanical study

The aim of this study was to analyze biomechanically the impact of bone cement augmentation on the fixation strength and cut-out resistance of Proximal Femoral Nail Antirotation (PFNA) and Trochanteric Fixation Nail Advanced (TFNA) head elements within the femoral head in a human cadaveric model with poor bone quality. Methodology: Fifteen pairs of fresh-frozen human cadaveric femoral heads were randomized to three sets of five pairs each for center-center implantation of either TFNA blade, TFNA screw, or PFNA blade. By splitting the specimens of each pair for treatment with or without bone cement augmentation, six study groups were created. All specimens were biomechanically tested under progressively increasing cyclic loading featuring a physiologic loading trajectory in a setup simulating a reduced intertrochanteric fracture with lack of posteromedial support. Number of cycles to 5° varus collapse was evaluated together with the corresponding load at failure. Results: Compared to the non-augmented state, all types of implants demonstrated significantly higher numbers of cycles to failure and load at failure following augmentation, p ≤ 0.03. Augmented TFNA blades resulted in highest numbers of cycles to failure and loads at failure (30492; 4049 N) followed by augmented PFNA blades (30033; 4003 N) and augmented TFNA screws (19307; 2930 N), p = 0.11. Augmented TFNA screws showed similar numbers of cycles to failure and loads at failure compared to both non-augmented TFNA and PFNA blades, P = 0.98.From a biomechanical perspective, bone cement augmentation significantly increases the cut-out resistance of instrumented TFNA and PFNA head elements and is a valid supplementary treatment option to these nailing procedures in poor bone quality.

Sensitivity analysis of biomechanical effect in vertebral body of two different augmenters

BackgroundTransvertebral Bone Graft and Augmentation (TBGA) has achieved good clinical effects in the treatment of osteoporotic vertebral compression fractures (OVCFs). This study aimed to investigate the postoperatively biomechanical effects of TBGA and compare the biomechanical sensitivity of two different augmenters: a cylindrical enhancement device (CED) and bone cement. MethodsFinite element models of the spine segment T11–L3 were created, including one model based on normal segment and the other three with L1 augmentation for pathological conditions. Three treatments were simulated including CED implant treatment A, CED implant treatment B, and bone cement treatment. The stress distribution and maximum displacement of the four models under different treatments were analyzed. A method of linear fitting of dummy variables was used to analyze the sensitivity of biomechanical parameters to the degree of osteoporosis (DO) and load. FindingsThe reduction of stress with increasing DO in augmented and adjacent vertebral bodies under bone cement augmentation was less than that under CED augmentation. The stress of augmented vertebral body and the adjacent vertebral body was most sensitive to extension and rotation loading conditions. As DO increasing, the bone cement augmentation significantly increased the stress level on the upper and lower endplates. InterpretationWhen the degree of osteoporosis increased, CED outperforms bone cement in terms of the stress reduction in augmented vertebral and adjacent vertebral, which could be beneficial for avoiding re-fracture. Using TBGA to treat OVCFs, especially with Plan B method, the condition of the pathological spine is closer to the original status in terms of the sensitivity to stress and the spinal range of motion. The TBGA treatment is sensitive to lateral bending and torsion, therefore patients should be advised to avoid high-risk motions like lateral bending and rotation.

Minimally invasive stabilization of thoracolumbar osteoporotic fractures

Minimally invasive stabilization of thoracolumbar osteoporotic fractures (OF) in neurologically intact patients is well established. Various posterior and anterior surgical techniques are available. The OF classification and OF score are helpful for defining the indications and choice of operative technique. This article gives an overview of the minimally invasive stabilization techniques, typical complications and outcome. Selective literature search and description of surgical techniques and outcome. Vertebral body augmentation alone can be indicated in painful but stable fractures of types OF1 and OF2 and to some extent for type OF3. Kyphoplasty has proven to be an effective and safe procedure with a favorable clinical outcome. Unstable fractures and kyphotic deformities (types OF3-5) should be percutaneously stabilized from posterior. The length of the pedicle screw construct depends on the extent of instability and deformity. Bone cement augmentation of the pedicle screws is indicated in severe osteoporosis but increases the complication rate. Restoration of stability of the anterior column can be achieved through additional vertebral body augmentation or rarely by anterior stabilization. Clinical and radiological short and mid-term results of the stabilization techniques are promising; however, the more invasive the surgery, the more complications occur. Minimally invasive stabilization techniques are safe and effective. The specific indications for the individual procedures are guided by the OF classification and the individual clinical situation of the patient.

The plate fixation strategy of complex proximal humeral fractures.

For complex proximal humeral fractures, severe displacement and comminuted fragments lead to poor clinical outcomes. Despite considerable management, the locking plate fixation is still a preference and the proper selection of its strategy for each individual seems to be essential. The available classification system of the fracture, determination of surgical intervention, the common complications and related causes, and the latest critical surgical strategies with locking plate fixation were discussed in this review. The frequent complications with complex proximal humeral fractures after operative treatment present a great challenge to orthopedic surgeons. In order to maintain the stability of locking plate fixation, several options including calcar screw, bone graft, bone cement augmentation, dual plate fixation, and fracture impaction were available for restoration of medial support. Restoration of medial support seems of importance to provide solid stability and reduced complication for the complex fractures with fixation of locking plates.

Changes of the adjacent discs and vertebrae in patients with osteoporotic vertebral compression fractures treated with or without bone cement augmentation

BACKGROUND CONTEXTAlthough vertebral augmentation with bone cement has been commonly used to treat symptomatic osteoporotic vertebral compression fractures, relatively little is known about the impact of augmentation on the adjacent spinal components. PURPOSETo determine the imaging effects of vertebral augmentation on the adjacent discs, the augmented vertebra, and the involved spinal segment. STUDY DESIGNRetrospective radiographic study. PATIENT SAMPLEPatients with acute osteoporotic vertebral compression fractures who underwent vertebral augmentation or nonoperative treatments. OUTCOME MEASURESOn baseline and follow-up mid-sagittal T2W magnetic resonance images, quantitative measurements of disc degeneration, including disc height, bulging, and signal, vertebral height, wedge angle, and segmental kyphotic angle were acquired. METHODSLumbar spine magnetic resonance images of patients with acute osteoporotic vertebral compression fractures at a local hospital in Eastern China between 2010 and 2017 were reviewed. Student's t-tests and χ2 tests were used to examine the differences of baseline and changes over time between vertebrae underwent vertebral augmentation and those did not. Paired t-tests were used to examine the differences between baseline and follow-up to study the changes of adjacent disc degeneration, creep deformity of the vertebra and progression of segmental kyphosis. RESULTSThere were 112 acute vertebral compression fractures (72 treated with kyphoplasty and 40 with nonoperative treatments) in 101 subjects. At final follow-up (mean 21.5 months), the cranial disc of the augmented vertebra decreased in height (p<.001), and both cranial and caudal discs decreased in signal intensity (p≤.02). The discs in the nonoperative group did not undergo such degenerative changes. For the fractured vertebra, vertebral height significantly decreased (p<.01 for both) and vertebral wedge angle significantly increased (p≤.01 for both), regardless of augmentation treatment or not. Segmental kyphotic angle significantly increased in vertebral fractures that underwent vertebral augmentation (p<.001), but not in those underwent nonoperative treatments. CONCLUSIONSPatients that underwent vertebral augmentation had more advanced disc degeneration at adjacent disc levels as compared to those without augmentation. The fractured vertebral body height decreased and the wedge angle increased, regardless of vertebral augmentation treatment or not. Vertebral augmentation may be associated with increased creep deformity of the adjacent vertebra and the progression of segmental kyphosis.

Venous Drainage of Lumbar Vertebral Bodies: Anatomic Study with Application to Kyphoplasty, Vertebroplasty, and Pedicle Screw Complications

Bone cement augmentation with polymethylmethacrylate is a reliable method for stabilizing osteoporotic compression fractures and improving fixation of pedicle screws. However, cement extrusion into the vertebral venous system can result in pulmonary cement embolism. The goal of this anatomic study was to identify the relationship between the internal/external vertebral plexus and neighboring abdominal caval system. Thirty-two lumbar vertebral levels were used in this study. Anterior abdominal dissection was performed to access the lumbar vertebral bodies through the peritoneal cavity, and a 16-gauge needle was placed into the center of each lumbar vertebral body at its anterior aspect. Fluoroscopy was used to confirm if the needle was correctly placed. Next, latex and/or continuous air injections were performed into each lumbar vertebral level (L1-L5). Observations confirmed if the latex or air traveled into the inferior vena cava. In addition, the spinal canal was opened to see if any latex was found to enter inside the vertebral canal in cadavers injected with the latex. Latex or air was found to flow into the inferior vena cava at all the lumbar vertebral levels. The latex/air was not observed in the spinal canal in any specimen. An exact knowledge of the lumbar vertebral venous anatomy is essential when procedures that could affect the vertebral venous system are involved. Its complexity and anatomic variability necessitate such an understanding to better prevent/understand possible complications associated with polymethylmethacrylate extrusion.

Posterior Vertebral Column Resection Combined With Bone Cement Augmentation of Pedicle Screw Fixation for Treatment of Severe Vertebral Compression Fractures With Kyphotic Deformity: A Retrospective Case Series.

This was a retrospective study. Severe osteoporotic vertebral compression fractures with kyphotic deformity are difficult to treat. The objective of this study was to investigate the clinical efficacy of posterior vertebral column resection (PVCR) combined with bone cement augmentation of pedicle screw fixation in the treatment of severe vertebral compression fractures with kyphotic deformity. The data of patients with a severe vertebral compression fracture and kyphotic deformity treated at our university between October 2013 and October 2017 were retrospectively reviewed. All patients underwent PVCR combined with bone cement augmentation of pedicle screw fixation and anterior column reconstruction. The operative time, intraoperative blood loss, postoperative complications, and screw stability at the last follow-up in all patients were documented. The clinical benefits were evaluated by the Visual Analog Scale (VAS) score, Oswestry Dysfunction Index (ODI), Japanese Orthopedic Association (JOA) scores, and Frankel classification. The mean Cobb angle, sagittal vertical axis, VAS score, JOA score, and ODI were 48.5±6.9 degrees, 44.0±5.7, 6.5±1.5, 11.2±2.7, and 59.0±5.7 before surgery, respectively. The average follow-up period was 28.7±3.2 months. The Frankel grade in 5 patients with neurological impairment improved from D to E after surgery. The average Cobb angles for kyphotic deformity, sagittal vertical axis, VAS score, JOA score, and ODI were 9.5±3.8 degrees, 18.3±3.5, 2.6±1.2, 20.5±3.6, and 20.7±4.0, respectively, at the last follow-up (all P<0.05 compared with before surgery). For patients with severe vertebral compression fractures and kyphotic deformity, PVCR combined with bone cement augmentation of pedicle screw fixation can restore the spine sequence to achieve good clinical efficacy. Clinical trials are necessary for confirmation.

Incidence and Management Trends of Osteoporotic Vertebral Compression Fractures in South Korea: A Nationwide Population-Based Study.

Study DesignA nationwide population-based study.PurposeOsteoporotic vertebral compression fracture (OVCF) is a major public health issue. This study examined the incidence and management trends of OVCF in South Korea. Overview of LiteratureThe incidence rates, management trends, and patterns of OVCF differ in different parts of the world. The age-standardized OVCF incidence rate in 2015 was higher in the United States and Asia than in Europe.MethodsA nationwide database (2012–2016) acquired from the Korean Health Insurance Review and Assessment Service was analyzed. International disease categories in the 10th revision of the International Statistical Classification of Diseases and Related Health Problems codes, medical procedure codes, and examination codes were used to identify and sort OVCF patients aged >50 years.ResultsThere were 644,500 OVCF cases from 2012 to 2016. OVCF was most common in patients in their seventies (45%) and the number of patients increased from 117,361 in 2012 to 139,889 in 2016 (p <0.001). During 2012–2016, 8.9% of patients visited the emergency department; of those, 54.3% were hospitalized and 35% underwent magnetic resonance imaging. In OVCF treatment, bone cement augmentation rates increased from 23.4% in 2012 to 25.2% in 2016 (p <0.001), while conservative treatment rates slightly decreased from 76.5% in 2012 to 74.7% in 2016 (p <0.001). The total health insurance cost was $193,210,353.55 in 2012 and $281,968,877.65 in 2016.ConclusionsThe 5-year incidence of OVCF per 100,000 persons was 852.24 cases, and 45% of OVCF in South Korea occurred in patients in their seventies. The bone cement augmentation rate and total cost of OVCF are continuously increasing.

Evaluation of fracture properties of cancellous bone tissues using digital image correlation/wedge splitting test method

The fracture mechanics (FM) parameters of cancellous bone tissues are very important from a clinical point of view especially for the bone cement augmentation. From the literature review, one can observe that the experimental determination of fracture mechanic parameters of cancellous bone are still lacking. This can be due to the conditions associated with the unstable crack propagation in the cancellous bone and lack of tools to extract and measure the parameters (like crack opening displacement (COD) and crack length) in the course of fracture tests, which are necessary to evaluate the fracture properties. To address above mentioned, a platform was developed integrating an optical measurement technique like digital image correlation (DIC) with classical wedge splitting test (WST) method to extract precise and real crack tip positions, crack opening displacement (COD) at each load step. These indeed used for the evaluation of the fracture mechanic properties (fracture toughness, specific fracture energy (Gf)) of the cancellous bone. Two approaches were used to evaluate the fracture mechanic properties of the bone. The first method is based on the global approach, which was widely used in the literature and the second method is based on the local approach. In this local approach, the local fracture energy (Gi) during the course of the test was evaluated, which give access to local fracture mechanics. The results evaluated by both the methods were in good accordance and compared with available literature. In addition, an attempt made to retrieve the real crack tip position at each load step during the test.

Effectiveness of posterior short-segmental fixation with bone cement augmentation for stage Ⅲ Kümmell's disease with spinal canal stenosis

To investigate the effectiveness of posterior short-segmental fixation with bone cement augmentation in treatment of stage Ⅲ Kümmell's disease with spinal canal stenosis. Between June 2012 and January 2017, 36 patients with stage Ⅲ Kümmell's disease and spinal canal stenosis were treated by posterior short-segmental fixation and bone cement augmentation. There were 12 males and 24 females, aged 55-83 years (mean, 73.5 years). The disease duration ranged from 2 to 8 months, with an average of 4.6 months. Preoperative bone mineral density examination showed that all patients had different degrees of osteoporosis in the spines. The lesion segments included T 10 in 4 cases, T 11 in 7 cases, T 12 in 8 cases, L 1 in 9 cases, and L 2 in 8 cases. The preoperative neural function was classified as grade B in 4 cases, grade C in 12 cases, grade D in 13 cases, and grade E in 7 cases according to Frankle classification. The operation time, intraoperative blood loss, and the volume of injected bone cement, and hospital stay were recorded. The visual analogue scale (VAS) score, Oswestry Disability Index (ODI), kyphotic Cobb angle, and the height of anterior edge of injured vertebra were recorded before operation, at 1 week after operation, and at last follow-up; and the leakage of bone cement was observed. All operations were completed successfully. The operation time was 90-145 minutes (mean, 110.6 minutes); the intraoperative blood loss was 198-302 mL (mean, 242.5 mL); the volume of injected bone cement was 8.3-10.5 mL (mean, 9.2 mL); the hospital stays were 7-12 days (mean, 8.3 days). All patients were followed up 12-26 months (mean, 24.5 months). At 1 week after operation, the neural function was classified as grade B in 2 cases, grade C in 8 cases, grade D in 12 cases, and grade E in 14 cases, which was significantly improved when compared with that before operation ( Z=2.000, P=0.047). The VAS score, ODI, the height of anterior edge of injured vertebra, and Cobb angle were significantly improved at 1 week and last follow-up when compared with preoperative values ( P<0.05); but there was no significant difference between 1 week and last follow-up ( P>0.05). Two cases had asymptomatic cement leakage to the intervertebral disc at 1 week after operation; and 1 case had adjacent vertebral fracture at 8 months after operation. No complication such as loosening or breaking of internal fixator occurred during the follow-up. Posterior short-segmental fixation with bone cement augmentation is a safe and effective surgical scheme for stage Ⅲ Kümmell's disease combined with spinal canal stenosis, which can avoid the aggravation of nerve injury and complications related to staying in bed.

Bone cement augmentation of the pedicle screw in spinal surgery

Osteoporosis is a common metabolic bone disease in the elderly. It may be one of the factors which contributes to instrumentation failure in spinal surgery. Bone cement augmentation of the pedicle screw is a technique to enhance fixation strength, and it is now mainly applied in patients with osteoporosis and revision surgery, as well as spinal tumor surgery. According to clinical studies, bone cement augmentation can decrease screw loosening rate, prevent correction loss of the spine deformity, and increase the fusion rate. Pedicle screw fracture and pulloutare rare following screw augmentation surgery. The pedicle screw loosening rates following screw augmentation surgery with bone cement are higher in patients with osteoporotic vertebral fracture and lower in patients with spinal degenerative diseases. The main material for bone cement augmentation is Polymethylmethacrylate, and the volume for each screw is about 1-3 ml. Some researchers suggest less volume use in thoracic vertebrae than lumbar vertebrae. Both traditional and cannulated screws can be applied as the augmented pedicle screws, as well as the expandable pedicle screw. Cannulated screws can decrease the risk of bone cement extravasation compared with traditional screws. The mini-mally invasive technique of screw augmentation with bone cement can be used both in primary spinal surgery and augmentation of loosed screws. The main complications of the bone cement augmentation technique are cement leakage and pulmonary cement em-bolism. X-ray fluoroscopy is generally used to detect cement extravasation during the bone cement procedure. The 3D navigation and neurological monitoring are also recommended to reduce cement leakage in some studies. Most local cement leakage events are asymptomatic and need no treatment. Management of pulmonary cement embolism depends on the clinical presentation and the position of the emboli, including regular follow-up, oxygen inhalation, anti-coagulation therapy and embolectomy.

Surgical treatment of low-grade chondrosarcoma involving the appendicular skeleton: long-term functional and oncological outcomes.

The traditional treatment for chondrosarcoma is wide local excision (WLE), as these tumors are resistant to chemotherapy and radiation treatment. While achieving negative margins has traditionally been the goal of chondrosarcoma resection, multiple studies have demonstrated good short-term results after intralesional procedures for low-grade chondrosarcomas (LGCS) with curettage and adjuvant treatments (phenol application, cauterization or cryotherapy) followed by either cementation or bone grafting. Due to the rarity of this diagnosis and the recent application of this surgical treatment modality to chondrosarcoma, most of the information regarding treatment outcomes is retrospective, with short or intermediate-term follow-up. The aim of this study was to assess the long-term results of patients with LGCS of bone treated with intralesional curettage (IC) treatment versus WLE. This retrospective analysis aims to characterize the oncologic outcomes (local recurrence, metastases) and functional outcomes in these two treatment groups at a single institution. Using an institutional musculoskeletal oncologic database, we retrospectively reviewed medical records of all patients with LGCS of the appendicular skeleton that underwent surgical treatment between 1985 and 2007. Thirty-two patients (33 tumors) were identified with LGCS; 17 treated with IC and 15 with WLE. Seventeen patients (18 tumors) with a minimum clinical and radiologic follow-up of 10years were included. Nine patients were treated with IC (four with no adjuvant, three with additional phenol, one with liquid nitrogen and one with H2O2) with either bone graft or cement augmentation, and nine others were treated with WLE and reconstruction with intercalary/osteoarticular allograft or megaprosthesis. The mean age at surgery was 41years (range 14-66years) with no difference (p = 0.51) between treatment cohorts. There was a mean follow-up of 13.5years in the intralesional cohort (range 10-19years) and 15.9years in the WLE cohort (range 10-28years, p = 0.36). Tumor size varied significantly between groups and was larger in patients treated with WLE (8.2 ± 3.1cm versus 5.4 ± 1.2cm, at the greatest dimension, p = 0.021). There were two local recurrences (LR), one in the intralesional group and one in the wide local excision group, occurring at 3.5months and 2.9years, respectively, and both required revision. No further LR could be detected with long-term follow-up. The MSTS score at final follow-up was significantly higher for patients managed with intralesional procedures (28.7 ± 1.7 versus 25.7 ± 3.4, p = 0.033). There were less complications requiring reoperation in the intralesional group compared with the wide local excision group, although this difference was not found to be statistically significant (one versus four patients, respectively; p = 0.3). This series of low-grade chondrosarcoma, surgically treated with an intralesional procedures, with 10-year follow-up, demonstrates excellent local control (88.9%). Complications were infrequent and minor and MSTS functional scores were excellent. Wide resection of LGCS was associated with lower MSTS score and more complications. In our series, the LR in both groups were detected within the first 3.5years following the index procedure, and none were detected in the late surveillance period.

INVESTIGATION INTO WHETHER OR NOT PMMA BONE CEMENT TRANSPEDICULAR SCREW AUGMENTATION STABILIZES PEDICLE SCREW LOOSENING

Pedicle screw loosening at the bone–screw interface is the main complication in pedicle screw fixation. The transpedicular polymethylmethacrylate screw augmentation technique has recently become the general technique used to re-operatively overcome pedicle screw loosening. This study investigates the fatigue resistance of PMMA bone cement augmentation. Twenty-seven porcine thoracic vertebral bodies were collected. The BMD was measured using dual X-ray absorptiometry. Each vertebral body was instrumented with one pedicle screw and mounted in a material testing system. Fatigue testing was performed by implementing a cranio-caudal sinusoidal, cyclic (5[Formula: see text]Hz) load. This study shows that transpedicular pedicle screw augmentation with PMMA exhibits similar fatigue resistance as traditional pedicle screw implantation. However, in histomophometrical analysis, the transpedicular pedicle screw augmentation with PMMA has greater anti-deformation capacity than traditional pedicle screw implantation. Transpedicular pedicle screw augmentation with PMMA improves more screw holding power to prevent pedicle screw loosening.

Screw tip augmentation leads to improved primary stability in the minimally invasive treatment of displaced intra-articular fractures of the calcaneus: a biomechanical study.

To investigate if the stability of minimally invasive screw osteosynthesis of displaced intra-articular calcaneal fractures (DIACF) can be effectively increased by an innovative approach to screw tip augmentation. In eight-paired human cadaver hindfoot specimens, DIACF of Sanders type IIB were treated with either standard screw osteosynthesis or with bone cement augmentation of the screw tips in the main fragments. The instrumented specimens were subjected to a cyclic loading protocol (9000 cycles, with stepwise increasing loads, 100-1000N). The interfragment motions were quantified as tuber fragment tilt (TFT) and posterior facet inclination angle (PFIA) using a 3-D motion analysis system. Böhler's angle (BA) was evaluated from X-rays. A load-to-failure test was performed after the cyclic loading protocol. All but one specimen of the augmented group withstood more cycles than the respective specimens of the non-augmented group. Mean cycles to failure for the failure criterion of 5° TFT were 7299 ± 1876 vs. 3864 ± 1810, corresponding to loads of 811N ± 195 vs. 481N ± 180, (P = 0.043). There were no significant differences observed in the PFIAs. The failure criterion of 5° BA was reached after a mean of 7929cycles ± 2004 in the augmented group and 4129cycles ± 2178 in the non-augmented group, corresponding to loads of 893N ± 200 vs. 513N ± 218, (P = 0,090). The mean load-to-failure of the four specimens in the augmented group that completed the cyclic loading was 1969N over a 1742-2483N range. Screw tip augmentation significantly improved the mechanical stability of the calcanei after osteosynthesis in terms of decreased tuber fragment tilts and less changes in Böhler's angle.

Biomechanical evaluation of a new gliding screw concept for the fixation of proximal humeral fractures.

AimsPlating displaced proximal humeral fractures is associated with a high rate of screw perforation. Dynamization of the proximal screws might prevent these complications. The aim of this study was to develop and evaluate a new gliding screw concept for plating proximal humeral fractures biomechanically.MethodsEight pairs of three-part humeral fractures were randomly assigned for pairwise instrumentation using either a prototype gliding plate or a standard PHILOS plate, and four pairs were fixed using the gliding plate with bone cement augmentation of its proximal screws. The specimens were cyclically tested under progressively increasing loading until perforation of a screw. Telescoping of a screw, varus tilting and screw migration were recorded using optical motion tracking.ResultsMean initial stiffness (N/mm) was 581.3 (sd 239.7) for the gliding plate, 631.5 (sd 160.0) for the PHILOS and 440.2 (sd 97.6) for the gliding augmented plate without significant differences between the groups (p = 0.11). Mean varus tilting (°) after 7500 cycles was comparable between the gliding plate (2.6; sd 1.9), PHILOS (1.2; sd 0.6) and gliding augmented plate (1.7; sd 0.9) (p = 0.10). Similarly, mean screw migration(mm) after 7500 cycles was similar between the gliding plate (3.02; sd 2.85), PHILOS (1.30; sd 0.44) and gliding augmented plate (2.83; sd 1.18) (p = 0.13). Mean number of cycles until failure with 5° varus tilting were 12702 (sd 3687) for the gliding plate, 13948 (sd 1295) for PHILOS and 13189 (sd 2647) for the gliding augmented plate without significant differences between the groups (p = 0.66).ConclusionBiomechanically, plate fixation using a new gliding screw technology did not show considerable advantages in comparison with fixation using a standard PHILOS plate. Based on the finding of telescoping of screws, however, it may represent a valid approach for further investigations into how to avoid the cut-out of screws.Cite this article: Y. P. Acklin, I. Zderic, J. A. Inzana, S. Grechenig, R. Schwyn, R. G. Richards, B. Gueorguiev. Biomechanical evaluation of a new gliding screw concept for the fixation of proximal humeral fractures. Bone Joint Res 2018;7:422–429. DOI: 10.1302/2046-3758.76.BJR-2017-0356.R1.