Percutaneous transpedicular vertebroplasty with calcium phosphate cement in the treatment of osteoporotic vertebral compression and burst fractures

Nanotechnology-enabled materials for hemostatic and anti-infection treatments in orthopedic surgery

The hemostatic and anti-infection treatments in the field of orthopedics are always the pivotal yet challenging topics. In the first part of this review, synthesized or naturally derived nanoscale agents and materials for hemostatic treatment in orthopedic surgery are introduced. The hemostatic mechanisms and the safety concerns of these nanotechnology-enabled materials are discussed. Beside the materials to meet hemostatic needs in orthopedic surgery, the need for antimicrobial or anti-infection strategy in orthopedic surgery also becomes urgent. Nanosilver and its derivatives have the most consistent anti-infective effect and thus high translational potential for clinical applications. In the second part, the factors affecting the antimicrobial effect of nanosilver and its application status are summarized. Finally, the status and translational potential of various nanotechnology-enabled materials and agents for hemostatic and anti-infective treatments in orthopedic surgery are discussed.

Pathomechanisms and management of osteoporotic pain with no traumatic evidence

Introduction

Osteoporosis is a pathological state with an unbalanced bone metabolism mainly caused by accelerated osteoporotic osteoclast activity due to a postmenopausal estrogen deficiency, and it causes some kinds of pain, which can be divided into two types: traumatic pain due to a fragility fracture from impaired rigidity, and pain derived from an osteoporotic pathology without evidence of fracture. We aimed to review the concepts of osteoporosis-related pain and its management.

Methods

We reviewed clinical and basic articles on osteoporosis-related pain, especially with a focus on the mechanism of pain derived from an osteoporotic pathology (i.e., osteoporotic pain) and its pharmacological treatment.

Results

Osteoporosis-related pain tends to be robust and acute if it is due to fracture or collapse, whereas pathology-related osteoporotic pain is vague and dull. Non-traumatic osteoporotic pain can originate from an undetectable microfracture or structural change such as muscle fatigue in kyphotic patients. Furthermore, basic studies have shown that the osteoporotic state itself is related to pain or hyperalgesia with increased pain-related neuropeptide expression or acid-sensing channels in the local tissue and nervous system. Traditional treatment for osteoporotic pain potentially prevents possible fracture-induced pain by increasing bone mineral density and affecting related mediators such as osteoclasts and osteoblasts. The most common agent for osteoporotic pain management is a bisphosphonate. Other non-osteoporotic analgesic agents such as celecoxib have also been reported to have a suppressive effect on osteoporotic pain.

Conclusions

Osteoporotic pain has traumatic and non-traumatic factors. Anti-osteoporotic treatments are effective for osteoporotic pain, as they improve bone structure and the condition of the pain-related sensory nervous system. Physicians should always consider these matters when choosing a treatment strategy that would best benefit patients with osteoporotic pain.

Nanotechnology for treating osteoporotic vertebral fractures

Osteoporosis is a serious public health problem affecting hundreds of millions of aged people worldwide, with severe consequences including vertebral fractures that are associated with significant morbidity and mortality. To augment or treat osteoporotic vertebral fractures, a number of surgical approaches including minimally invasive vertebroplasty and kyphoplasty have been developed. However, these approaches face problems and difficulties with efficacy and long-term stability. Recent advances and progress in nanotechnology are opening up new opportunities to improve the surgical procedures for treating osteoporotic vertebral fractures. This article reviews the improvements enabled by new nanomaterials and focuses on new injectable biomaterials like bone cements and surgical instruments for treating vertebral fractures. This article also provides an introduction to osteoporotic vertebral fractures and current clinical treatments, along with the rationale and efficacy of utilizing nanomaterials to modify and improve biomaterials or instruments. In addition, perspectives on future trends with injectable bone cements and surgical instruments enhanced by nanotechnology are provided.

Outcome of percutaneous balloon kyphoplasty in vertebral compression fractures

BACKGROUND

Incidence of vertebral compression fractures (VCFs) is increasing due to increase in human life expectancy and prevalence of osteoporosis. Vertebroplasty had been traditional treatment for pain, but it neither attempts to restore vertebral body height nor eliminates spinal deformity and is associated with a high rate of cement leakage. Balloon kyphoplasty involves introduction of inflatable balloon into the fractured body of vertebra for elevation of the end-plates prior to fixation of the fracture with bone cement. This study evaluates short term functional and radiological outcomes of balloon kyphoplasty. The secondary aim is to explore short-term complications of the procedure.

MATERIALS AND METHODS

A retrospective study of 199 kyphoplasty procedures in 135 patients from March 2009 to March 2012 were evaluated with short form-36 (SF-36) score, visual analogue scale (VAS), detailed neurological and radiological evaluations. The mean followup was 18 months (range 12-20 months). Statistical analysis including paired sample t-test was done with statistical package for social sciences.

RESULTS

Statistically significant improvements in SF-36 (from 34.29 to 48.53, an improvement of 14.24, standard deviation (SD) - 20.08 P < 0.0001), VAS (drop of 4.49, from 6.74 to 2.24, SD - 1.44, P < 0.0001), percentage restoration of lost vertebral height (from 30.62% to 16.19%, improvement of 14.43%, SD - 15.37, P < 0.0001) and kyphotic angle correction (from 17.41° to 10.59°, improvement of 6.82, SD - 7.26°, P < 0.0001) were noted postoperatively. Six patients had cement embolism, 65 had cement leak and three had adjacent level fracture which required repeat kyphoplasty later. One patient with history of ischemic heart disease had cardiac arrest during the procedure. No patients had neurological deterioration in the followup period.

CONCLUSIONS

Kyphoplasty is a safe and effective treatment for VCFs. It improves physical function, reduces pain and corrects kyphotic deformity.

Minimally invasive surgery for radial neck fractures using bone paste

We treat radial neck fractures by a minimally invasive technique using bone paste. The indication of this technique is radial neck fractures in which the continuity with the radius shaft is retained. We have treated 13 patients using this technique. As a result, the average range of motion of the elbow was 90° for supination and 92° for pronation, +5° for extension, and 141° for flexion. The reduced position at surgery was kept unchanged until bone union. None of the patients complained of pain. The surgical scar was unnoticeable. This technique is recommended surgery for the radial neck fractures when the indication is appropriate.

Novel intramedullary-fixation technique for long bone fragility fractures using bioresorbable materials

Almost all of the currently available fracture fixation devices for metaphyseal fragility fractures are made of hard metals, which carry a high risk of implant-related complications such as implant cutout in severely osteoporotic patients. We developed a novel fracture fixation technique (intramedullary-fixation with biodegradable materials; IM-BM) for severely weakened long bones using three different non-metallic biomaterials, a poly(l-lactide) (PLLA) woven tube, a nonwoven polyhydroxyalkanoates (PHA) fiber mat, and an injectable calcium phosphate cement (CPC). The purpose of this work was to evaluate the feasibility of IM-BM with mechanical testing as well as with an animal experiment. To perform mechanical testing, we fixed two longitudinal acrylic pipes with four different methods, and used them for a three-point bending test (N = 5). The three-point bending test revealed that the average fracture energy for the IM-BM group (PLLA + CPC + PHA) was 3 times greater than that of PLLA + CPC group, and 60 to 200 times greater than that of CPC + PHA group and CPC group. Using an osteoporotic rabbit distal femur incomplete fracture model, sixteen rabbits were randomly allocated into four experimental groups (IM-BM group, PLLA + CPC group, CPC group, Kirschner wire (K-wire) group). No rabbit in the IM-BM group suffered fracture displacement even under full weight bearing. In contrast, two rabbits in the PLLA + CPC group, three rabbits in the CPC group, and three rabbits in the K-wire group suffered fracture displacement within the first postoperative week. The present work demonstrated that IM-BM was strong enough to reinforce and stabilize incomplete fractures with both mechanical testing and an animal experiment even in the distal thigh, where bone is exposed to the highest bending and torsional stresses in the body. IM-BM can be one treatment option for those with severe osteoporosis.

Experimental and computational approach investigating burst fracture augmentation using PMMA and calcium phosphate cements

The aim of the study was to use a computational and experimental approach to evaluate, compare and predict the ability of calcium phosphate (CaP) and poly (methyl methacrylate) (PMMA) augmentation cements to restore mechanical stability to traumatically fractured vertebrae, following a vertebroplasty procedure. Traumatic fractures (n = 17) were generated in a series of porcine vertebrae using a drop-weight method. The fractured vertebrae were imaged using μCT and tested under axial compression. Twelve of the fractured vertebrae were randomly selected to undergo a vertebroplasty procedure using either a PMMA (n = 6) or a CaP cement variation (n = 6). The specimens were imaged using μCT and re-tested. Finite element models of the fractured and augmented vertebrae were generated from the μCT data and used to compare the effect of fracture void fill with augmented specimen stiffness. Significant increases (p < 0.05) in failure load were found for both of the augmented specimen groups compared to the fractured group. The experimental and computational results indicated that neither the CaP cement nor PMMA cement could completely restore the vertebral mechanical behavior to the intact level. The effectiveness of the procedure appeared to be more influenced by the volume of fracture filled rather than by the mechanical properties of the cement itself.

Current status of percutaneous vertebroplasty and percutaneous kyphoplasty--a review

Percutaneous vertebroplasty (PV) and kyphoplasty (PK) are the 2vertebral augmentation procedures that have emerged as minimally invasive surgical options to treat painful vertebral compression fractures (VCF) during the last 2 decades. VCF may either be osteoporotic or tumor-associated. Two hundred million women are affected by osteoporosis globally. Vertebral fracture may result in acute pain around the fracture site, loss of vertebral height due to vertebral collapse, spinal instability, and kyphotic deformity. The main goal of the PV and PK procedures is to give immediate pain relief to patients and restore the vertebral height lost due to fracture. In percutaneous vertebroplasty, bone cement is injected through a minimal incision into the fractured site. Kyphoplasty involves insertion of a balloon into the fractured site, followed by inflation-deflation to create a cavity into which the filler material is injected, and the balloon is taken out prior to cement injection. This literature review presents a qualitative overview on the current status of vertebral augmentation procedures,especially PV and PK, and compares the efficacy and safety of these 2 procedures. The review consists of a brief history of the development of these 2 techniques, a discussion on the current research on the bone cement, clinical outcome of the 2 procedures, and it also sheds light on ongoing and future research to maximize the efficacy and safety of vertebral augmentation procedures.

Development of calcium phosphate cement for the augmentation of traumatically fractured porcine specimens using vertebroplasty

The study aim was to develop and apply an experimental technique to determine the biomechanical effect of polymethylmethacrylate (PMMA) and calcium phosphate (CaP) cement on the stiffness and strength of augmented vertebrae following traumatic fracture. Twelve burst type fractures were generated in porcine three-vertebra segments. The specimens were randomly split into two groups (n=6), imaged using microCT and tested under axial loading. The two groups of fractured specimens underwent a vertebroplasty procedure, one group was augmented with CaP cement designed and developed at Queen's University Belfast. The other group was augmented with PMMA cement (WHW Plastics, Hull, UK). The specimens were imaged and re-tested . An intact single vertebra specimen group (n=12) was also imaged and tested under axial loading. A significant decrease (p<0.01) was found between the stiffness of the fractured and intact groups, demonstrating that the fractures generated were sufficiently severe, to adversely affect mechanical behaviour. Significant increase (p<0.01) in failure load was found for the specimen group augmented with the PMMA cement compared to the pre-augmentation group, conversely, no significant increase (p<0.01) was found in the failure load of the specimens augmented with CaP cement, this is attributed to the significantly (p<0.05) lower volume of CaP cement that was successfully injected into the fracture, compared to the PMMA cement. The effect of the percentage of cement fracture fill, cement modulus on the specimen stiffness and ultimate failure load could be investigated further by using the methods developed within this study to test a more injectable CaP cement.

Vertebroplasty Using Calcium Phosphate Cement for Osteoporotic Vertebral Fractures: Study of Outcomes at a Minimum Follow-up of Two Years

STUDY DESIGN

A case-series study.

PURPOSE

To assess the long-term clinical and radiographic outcomes after vertebroplasty using calcium phosphate cement (CPC) for treatment of osteoporotic vertebral fractures (OVF).

OVERVIEW OF LITERATURE

Vertebroplasty has become common for the treatment of OVF. However, few studies have reported the clinical application of CPC to vertebroplasty.

METHODS

We reviewed 86 consecutive patients undergoing 99 vertebroplasties using CPC. Following repositioning and curettage of the pathological soft tissue of the vertebral body (VB), vertebroplasty using CPC was performed in patients with osteoporotic burst fracture and pseudoarthrosis (procedure A). Vertebroplasty was also performed in patients with osteoporotic compression fractures (procedure B). Back pain and lower back pain were evaluated using the visual analogue scale (VAS). The VB deformity index was measured in a lateral radiograph as the ratio of the VB's height to its longitudinal diameter.

RESULTS

The mean age at time of surgery was 77 years old. The mean duration of follow-up was forty-four months. All patients reported decreased pain according to the VAS immediately after vertebroplasty, and pain relief was maintained at the last follow-up in all patients without new OVFs. Complete bone union was observed in all cases by six months after surgery. The mean recovery rate of deformity index was 5.9% in procedure A and 0.02% in procedure B at the final follow-up visit.

CONCLUSIONS

Vertebroplasty using CPC gave a satisfactory outcome and no delayed complications in elderly patients with osteoporotic vertebral fractures at follow-up times of at least two years.

Filler Materials Used in Kyphoplasty and Vertebroplasty for Osteoporotic Vertebral Compression Fractures

Osteoporosis is the most common metabolic bone disease and the most common cause of fractures in older adults. Vertebral compression fracture (VCF) is the most common complication in patients with osteoporosis. At present, vertebroplasty (VP) and kyphoplasty (KP) are two minimally invasive techniques used to treat osteoporotic vertebral compression fractures. In clinical use, KP and VP have stable and reliable therapeutic effects. However, there are still some complications and issues surrounding KP and VP application, and for long-term clinical follow-up. Thus, it is important to continue to improve the technology of the filler materials used in KP and VP in order to evolve the biomechanical characteristics of the postoperative vertebra, and to reduce the incidence of complications. The filler materials used for both techniques require good biocompatibility, good biomechanical strength and stiffness, and good radiopacity for the fluoroscopy guided procedures. PMMA and new filler materials (calcium phosphate cement, calcium sulfate cement, composite materials) are now available for clinical use. In this review paper, we will focus on the issues and characteristics of these filler materials.

Management of osteoporotic vertebral fractures

Osteoporotic vertebral fractures are associated with considerable reduction of quality of life, morbidity, and mortality. The management of patients with vertebral fractures should include treatment for osteoporosis and measures to reduce pain and improve mobility. This article provides information for management and rehabilitation of vertebral fractures based on clinical experience and literature.

Vertebroplasty and kyphoplasty: a comparative review of efficacy and adverse events

Vertebroplasty and kyphoplasty have become common surgical techniques for the treatment of vertebral compression fractures. Vertebroplasty involves the percutaneous injection of bone cement into the cancellous bone of a vertebral body with the goals of pain alleviation and preventing further loss of vertebral body height. Kyphoplasty utilizes an inflatable balloon to create a cavity for the cement with the additional potential goals of restoring height and reducing kyphosis. Vertebroplasty and kyphoplasty are effective treatment options for the reduction of pain associated with vertebral body compression fractures. Biomechanical studies demonstrate that kyphoplasty is initially superior for increasing vertebral body height and reducing kyphosis, but these gains are lost with repetitive loading. Complications secondary to extravasation of cement include compression of neural elements and venous embolism. These complications are rare but more common with vertebroplasty. Vertebroplasty and kyphoplasty are both safe and effective procedures for the treatment of vertebral body compression fractures.

Preparation and characterization of a novel strontium-containing calcium phosphate cement with the two-step hydration process

A novel Sr-containing calcium phosphate cement (CPC) with excellent compressive strength, good radiopacity and suitable setting time was developed in this work. The two-step hydration reaction resulted in a high compressive strength, with a maximum of up to 74.9MPa. Sr was doped into the calcium-deficient hydroxyapatite as a hydrated product during the hydration reaction of the CPC. Because of the existence of Sr element and the compact microstructure after hydration, the Sr-containing CPC shows good radiopacity. It is expected to be used in orthopedic and maxillofacial surgery for bone defects repairing.

Kyphoplasty and vertebroplasty

Percutaneous vertebroplasty is the injection of a vertebral compression fracture (VCF) with bone cement, generally polymethylmethacrylate. Percutaneous kyphoplasty is the placement of balloons into the vertebral body with an inflation/deflation sequence to create a cavity before the cement injection. These procedures are most often performed in a percutaneous fashion on an outpatient (or short stay) basis. The procedure is indicated for painful VCFs due to osteoporosis or malignancy, and painful hemangiomas. The procedure may have efficacy in painful vertebral metastasis and traumatic compression fractures. Much evidence favors the use of this procedure for pain associated with these disorders. The overall risks of the procedure are low, but serious complications (including spinal cord compression) can occur. With good patient selection and careful technique, these complications are avoidable, making the risk-to-benefit ratio highly favorable.

Influence of a novel radiopacifier on the properties of an injectable calcium phosphate cement

An injectable calcium phosphate cement (CPC) with excellent radiopacity was proposed by introducing a novel radiopacifier, strontium carbonate, into the powder phase of CPC. The results showed that the cement showed improved radiopacity even when the content of strontium carbonate was only 8 or 12wt.%. The addition of 8 or 12wt.% strontium carbonate clearly improved the injectability and compressive strength of the cement. Furthermore, the addition of strontium carbonate influenced the pore distribution in the cement. An injectable CPC containing 8 or 12wt.% strontium carbonate has the potential for use in procedures such as vertebroplasty and kyphoplasty.

Histological and mechanical evaluation of self-setting calcium phosphate cements in a sheep vertebral bone void model

We investigated the histological and compressive properties of three different calcium phosphate cements (CPCs) using a sheep vertebral bone void model. One of the CPCs contained barium sulfate to enhance its radiopacity. Bone voids were surgically created in the lumbar region of 23 ovine spines - L3, L4, and L5 (n = 69 total vertebral bodies) - and the voids were filled with one of the three CPCs. A fourth group consisted of whole intact vertebrae. Histologic evaluation was performed for 30 of the 69 vertebrae 2 or 4 months after surgery along with radiographic evaluation. Compressive testing was performed on 39 vertebrae 4 months after surgery along with micro-CT analysis. All three CPCs were biocompatible and extremely osteoconductive. Osteoclasts associated with adjacent bone formation suggest that each cement can undergo slow resorption and replacement by bone and bone marrow. Compressive testing did not reveal a significant difference in the ultimate strength, ultimate strain, and structural modulus, among the three CPCs and intact whole vertebrae. Micro-CT analysis revealed good osseointegration between all three CPCs and adjacent bone. The barium sulfate did not affect the CPCs biocompatibility or mechanical properties. These results suggest that CPC might be a good alternative to polymethylmethacrylate for selected indications.

Risk factors of developing new symptomatic vertebral compression fractures after percutaneous vertebroplasty in osteoporotic patients

Percutaneous vertebroplasty (PVP) is an efficient procedure to treat pain due to osteoporotic vertebral compression fractures (OVCFs). However, some patient populations experience recurrent vertebral fracture after initial successful procedure. There are a lot of literatures about the effectiveness of this procedure but few concerning the development of recurrent, new compression fracture. This is a retrospective review of all PVPs performed in author's institution from September 1999 to December 2001 to investigate the factors related to the development of new symptomatic OVCFs after PVPs. A retrospective review of 244 cases of PVP for symptomatic OVCFs at 382 levels was performed. Sociodemographic, clinical, radiologic, and procedural data were analyzed and compared between the two patient groups (control group : no further symptomatic OVCFs after the initial PVP, "new symptomatic fracture" group: with newly developed symptomatic OVCF). Statistical analysis was performed between the variables of the two groups. Survival analysis was performed using the Kaplan-Meier method. Over all, 38 among 244 treated patients (15.6%) had experienced newly developed symptomatic OVCF(s) during the follow up period (mean 52.5 months). Old age and the presence of multiple treated vertebrae at the initial PVP were assessed as a strong parameter for predicting new symptomatic OVCF. With increasing preoperative wedging deformity the risk of developing new symptomatic OVCF decreased. The Kaplan-Meier estimate of the 1 year fracture-free rate was 92.2%. The Kaplan-Meier curve showed that 7.8% of the patients would experience new symptomatic OVCF within 1 year after initial PVP. A preoperative only mild wedge deformity of the fractured vertebra(e) could indicate the increased risk of developing new symptomatic OVCF after vertebroplasty.

[Modified percutaneous balloon kyphoplasty at osteolysis of 11th thoracic vertebra and communication with the spinal canal. Case report and review of the literature]

This paper presents the case report of a 67-year-old man who came to our hospital suffering from severe osteolysis of the 11th thoracic vertebral body. The patient has been suffering from renal cell carcinoma for 2 years. During a routine control the above-mentioned lesion was found by chance. A few days later pain started in the thoracolumbar region. Treatment was intended to be palliative. Therefore, we looked for an option to stabilize the vertebral body as minimally invasive as possible. Because of a destroyed trailing edge of the vertebra, "normal" kyphoplasty was not possible. For this reason, we performed a modification, using one filled balloon as a kind of curtain between the vertebral body and spinal canal. With this technique we achieved an optimal filling of the destroyed vertebral body with cement, without any leakage. Two days postoperatively, the patient could leave our hospital without any pain symptoms.

Osseous integration of calcium phosphate in osteoporotic vertebral fractures after kyphoplasty: initial results from a clinical and experimental pilot study

INTRODUCTION

This study evaluated the radiological changes at the bone-cement interface of calcium phosphate cement (CPC) and polymethylmethacrylate (PMMA) 12 months after kyphoplasty. In a pilot experiment, we additionally performed a histomorphometric analysis in osteopenic foxhounds to analyze the process of osseous integration of CPC and PMMA.

METHODS

Twenty postmenopausal female patients with 46 vertebral compression fractures (VCF) were treated by kyphoplasty, utilizing CPC (N=28) or PMMA (N=18) for intravertebral stabilization. After a 12-month follow-up, we measured the density changes of border voxels at the bone-cement interface by computed tomography (CT) using dedicated software algorithms. We defined the border-voxel density (BVD) as a parameter of cement resorption at the interface. We also investigated the bone-implant interface in three osteopenic foxhounds by histomorphometry 3, 6, and 12 months after cement implantation.

RESULTS

Twelve months after kyphoplasty, only CPC showed a significant decrease of the BVD compared to PMMA (p<0.01), indicating a slow progress of resorption at the interface. Histomorphometry of the dog vertebrae showed near total bone coverage of CPC implants, whereas the PMMA surface exhibited only 30% direct bone contact (p<0.01). We also observed a time-dependent increase in the number of discernable osteons close to the interface of CPC, but no bone tissue within PMMA (p<0.01).

CONCLUSIONS

The decrease of the BVD 12 months after kyphoplasty may indicate osseous integration of CPC by: (1) the ingrowth of bone tissue and (2) osteonal penetration close to the interface.

Reduction of pain and fracture incidence after kyphoplasty: 1-year outcomes of a prospective controlled trial of patients with primary osteoporosis

Previously, we reported significantly reduced pain and improved mobility persisting for 6 months after kyphoplasty of chronically painful osteoporotic vertebral fractures in the first prospective controlled trial. Since improvement of spinal biomechanics by restoration of vertebral morphology may affect the incidence of fracture, long-term clinical benefit and thereby cost-effectiveness, here we extend our previous work to assess occurrence of new vertebral fractures and clinical parameters 1 year after kyphoplasty compared with a conservatively treated control group. Sixty patients with osteoporotic vertebral fractures due to primary osteoporosis were included: 40 patients were treated with kyphoplasty, 20 served as controls. All patients received standard medical treatment. Morphological characteristics, new vertebral fractures, pain (visual analog scale), physical function [European Vertebral Osteoporosis Study (EVOS) score] (range 0-100 each) and back-pain-related doctors' visits were re-assessed 12 months after kyphoplasty. There were significantly fewer patients with new vertebral fractures of the thoracic and lumbar spine, after 12-months, in the kyphoplasty group than in the control group (P=0.0084). Pain scores improved from 26.2 to 44.4 in the kyphoplasty group and changed from 33.6 to 34.3 in the control group (P=0.008). Kyphoplasty treated patients required a mean of 5.3 back-pain-related doctors' visits per patient compared with 11.6 in the control group during 12 months follow-up (P=0.006). Kyphoplasty as an addition to medical treatment and when performed in appropriately selected patients by an interdisciplinary team persistently improves pain and reduces occurrence of new vertebral fractures and healthcare utilization for at least 12 months in individuals with primary osteoporosis.

Bioactive bone cements containing nano-sized titania particles for use as bone substitutes

Three types of bioactive polymethylmethacrylate (PMMA)-based bone cement containing nano-sized titania (TiO2) particles were prepared, and their mechanical properties and osteoconductivity are evaluated. The three types of bioactive bone cement were T50c, ST50c, and ST60c, which contained 50 wt% TiO2, and 50 and 60 wt% silanized TiO2, respectively. Commercially available PMMA cement (PMMAc) was used as a control. The cements were inserted into rat tibiae and allowed to solidify in situ. After 6 and 12 weeks, tibiae were removed for evaluation of osteoconductivity using scanning electron microscopy (SEM), contact microradiography (CMR), and Giemsa surface staining. SEM revealed that ST60c and ST50c were directly apposed to bone while T50c and PMMAc were not. The osteoconduction of ST60c was significantly better than that of the other cements at each time interval, and the osteoconduction of T50c was no better than that of PMMAc. The compressive strength of ST60c was equivalent to that of PMMAc. These results show that ST60c is a promising material for use as a bone substitute.

Vertebroplasty and kyphoplasty: a comprehensive review

Vertebroplasty and kyphoplasty are relatively new techniques used to treat painful vertebral compression fractures (VCFs). Vertebroplasty is the injection of bone cement, generally polymethyl methacrylate (PMMA), into a vertebral body (VB). Kyphoplasty is the placement of balloons (called "tamps") into the VB, followed by an inflation/deflation sequence to create a cavity prior to the cement injection. These procedures are most often performed in a percutaneous fashion on an outpatient (or short stay) basis. The mechanism of action is unknown, but it is postulated that stabilization of the fracture leads to analgesia. The procedures are indicated for painful VCFs due to osteoporosis or malignancy, and for painful hemangiomas. These procedures may be efficacious in treating painful vertebral metastasis and traumatic VCFs. Much evidence favors the use of these procedures for pain associated with the aforementioned disorders. The risks associated with the procedures are low but serious complications can occur. These risks include spinal cord compression, nerve root compression, venous embolism, and pulmonary embolism including cardiovascular collapse. The risk/benefit ratio appears to be favorable in carefully selected patients. The technical aspects of the procedures are presented in detail along with guidelines for patient selection. A comprehensive review of the evidence for the procedures and the reported complications is presented.

Decreases in the number and severity of morphometrically defined vertebral body deformities after kyphoplasty

Object

Vertebral body (VB) deformities have been associated with increased patient morbidity and mortality rates. The aim of this retrospective, consecutive single-center cohort study was to determine the effectiveness of kyphoplasty in reducing morphometrically defined VB deformity, including deformity shape types (wedge, biconcave, or crush) and grade (severity).

Methods

The authors identified 100 patients (70% women; mean age 76.1 years) in whom 138 vertebral fractures (T-4 through L-5; mean fracture age 2.7 months) that were treated between May 2000 and December 2001 were radiographically evaluated preoperatively and at the last follow-up visit (mean follow-up duration 16.9 months). Fractures were divided into four groups by level: T5–9 (28 fractures), T10–12 (41), L1–2 (42), and L3–5 (27). Anterior, mid-line, posterior, and predicted posterior vertebral heights for fractured and adjacent unfractured reference vertebrae were measured on lateral radiographs. The deformity type and grade were mathematically defined using the modified methods of McCloskey–Kanis and Black.

The total number of deformities decreased from 89.9 to 53.6% after kyphoplasty (p < 0.0001). The number of fractures with wedge, biconcave, or crush deformity decreased 22.5, 59.1, and 67.7% (p = 0.0699, p = 0.0222, p = 0.0007), respectively. The number of the more severe Grade 2 deformities decreased (79.7 to 37.0%; p < 0.0001). Kyphoplasty effectively decreased the number of deformed fractures in all vertebral level groups (T5–9, p = 0.0023; T10–12, p = 0.0105; L1–2, p < 0.0001; L3–5, p = 0.0028).

Conclusions

Kyphoplasty resulted in significant normalization of vertebral shapes in patients with symptomatic vertebral fractures, reducing the number and severity of deformed fractures postoperatively.

Calcium phosphate cement leakage after percutaneous vertebroplasty for osteoporotic vertebral fractures: risk factor analysis for cement leakage

OBJECT

The purpose of this study was to analyze the risk factors for leakage of calcium phosphate cement (CPC) after vertebroplasty for osteoporotic vertebral fractures and to determine whether the vertebral body (VB) leakage caused any changes in the therapeutic benefits.

METHODS

Between August 2000 and April 2002, the authors performed 65 CPC-assisted vertebroplasty procedures in 55 patients with thoracic or lumbar osteoporotic vertebral fractures. Back and low-back pain were evaluated using the visual analog scale and the duration of analgesic medication requirement. Factors related to CPC leakage and the postoperative outcome were analyzed. There was a small amount of VB CPC leakage in 23 cases. In 10 of 23 cases, leakage into the epidural space was found. Although VB CPC leakage was independently associated with high initial age, female sex, high bone mineral density (BMD), short injury-surgery interval, and injection via the unipedicular route in the logistic regression analysis, there was no factor associated with CPC leakage into the epidural space. Cement leakage into the epidural space reduced the immediate therapeutic effects on fracture-related pain (p = 0.0128). All patients in whom cement leaked into the epidural space had improved by the 2-week follow-up examination.

CONCLUSIONS

Advanced initial age, female sex, high BMD, a short interval from injury to surgery, and injection via the unipedicular route may increase the incidence of CPC leakage. Cement leakage into the epidural space attenuated only the immediate therapeutic effects of CPC-assisted vertebroplasty.

[Extravertebral cement drainage with occlusion of the extradural venous plexus into the vena cava after vertebrobplasty. Case report and review of the literature]

This paper presents the case report of an 88 year old female who came to hospital suffering from a severe lower back pain. Ten days before, she had undergone a vertebroplasty with injection of cement into lumbar vertebra 3 because of an osteoporotic fracture. This treatment did not result in a reduction of the lower back pain, which was the main reason for the procedure. However, the patient claimed to have increasing pain radiating to her left leg. Furthermore, she suffered from numbness of her left leg. Clinical examination showed a lack of power in this leg according to hip flexion with a degree of 3/5. X-ray examinations showed paravertebral cement particles and led to the suspicion that the paravertebral cement had caused nerve root compression. MRI and CT myelography showed that the cement had drained into the intraspinal, extradural venous plexus (Batson's plexus). The plexus was filled out with cement between L2 and L5 on both sides. There was nearly no cement in the fractured vertebra L3, but cement had also run onto the paravertebral veins up to the vena cava, which was also involved. The cemented veins had led to a stenosis of the neuroforamina L2 and L3 on the left side. The result was compression of left L3 nerve root. After consulting with our vascular surgeons, we decided on a non-operative treatment. We prescribed a lumbar brace as external stabilisation and as an antithrombotic treatment we gave the patient weight adapted low molecular weight heparin.

[Percutaneous cementing techniques of the spine -- chances and limits]

Vertebroplasty and Kyphoplasty represent minimal-invasive techniques for cement augmentation of vertebral bodies. Both procedures are successfully used for pain-relieving stabilizations of osteoporotic fractures or malignant processes. Advantages of kyphoplasty over vertebroplasty are to be seen in the possibility of deformity correction as well as in a decreased risk of cement extrusions which represent the most important potential for clinical complications. Long-term experiences with the effect of cementing are sparse. Thus it seems even more important, to judge indications and possibilities realistically. The decision whether and when to perform an augmentation is influenced by multiple factors. These include age of the patient, age of the fracture, degree of deformation and further degenerative changes of the spine. This article summarizes the present research and literature und is thought to provide guidelines for the aforementioned decision making processes.

Vertebroplasty for osteoporotic spine fracture: prevention and treatment

There is a relatively high prevalence of osteoporotic vertebral compression fractures (VCFs) in the elderly population, especially in women aged 50 or older. The result of these VCFs is increased morbidity and mortality in the short and long term. Medical treatment of these fractures includes bed rest, orthotics, analgesic medication and time. Percutaneous vertebroplasty (PVP) consists of percutaneous injection of biomaterial, such as methylmethacrylate, into the VCF to produce stability and pain relief. Biomechanical testing has shown that PVP can restore strength and stiffness of the vertebral body to the pre-fracture levels. Clinical results show immediate and maintained pain relief in 70-95% of the patients. Possible major complications include cement leakage into the spinal canal or into the venous system. Additionally, percutaneous vertebroplasty may alter the normal loading behavior of the adjacent vertebral body, and there is an increased risk of adjacent segment VCF. Kyphoplasty is a new technique, which introduces a balloon into the vertebral body transpedicularly to reduce the VCF while creating a cavity for the cement injection. This technique has the benefit of kyphosis reduction as well as less cement leakage. Research continues into the development of injectable biomaterials that are resorbable and allow for new bone formation. Vertebroplasty and kyphoplasty are safe and effective in the treatment of osteoporotic VCFs. They may allow for a faster return to function, and thus avoid the morbidity associated with medical treatment.

Effects of lumbar disc surgery on bone mineral density in women with lumbar disc disease

This prospective study evaluated 60 reproductive-age and postmenopausal women with lumbar disc disease to demonstrate the short-term effects of lumbar disc surgery on bone mineral density (BMD). Lumbar BMD was measured preoperatively and 3 months postoperatively by dual-energy X-ray absorptiometry (DEXA). Surgery was performed at only one level (L3-L4) and consisted of partial hemilaminectomy, discectomy, and, if necessary, partial facetectomy. Before surgery, 50% of the patients had osteopenia, and 31.7% had osteoporosis. After surgery, BMD decreased 5.5% in L3 vertebrae (P=.07), 14% in L4 vertebrae (P=.003), and 4.6% in L1-L4 (P=.039). Six of 11 patients with normal BMD before surgery became osteopenic postoperatively; 9 of 30 women with osteopenia fulfilled criteria for osteoporosis after surgery. Reproductive-age and postmenopausal women undergoing surgery for lumbar disc disease are at risk of bone loss and should be spared an extensive procedure, which can further increase the amount of bone lost. All women for whom a surgical intervention is planned should be evaluated by DEXA preoperatively and postoperatively.