An injectable calcium phosphate cement as a bone-graft substitute in the treatment of displaced lateral tibial plateau fractures

Temporal response of an injectable calcium phosphate material in a critical size defect

BACKGROUND

Calcium phosphate-based bone graft substitutes are used to facilitate healing in bony defects caused by trauma or created during surgery. Here, we present an injectable calcium phosphate-based bone void filler that has been purposefully formulated with hyaluronic acid to offer a longer working time for ease of injection into bony defects that are difficult to access during minimally invasive surgery.

METHODS

The bone substitute material deliverability and physical properties were characterized, and in vivo response was evaluated in a critical size distal femur defect in skeletally mature rabbits to 26 weeks. The interface with the host bone, implant degradation, and resorption were assessed with time.

RESULTS

The calcium phosphate bone substitute material could be injected as a paste within the working time window of 7-18 min, and then self-cured at body temperature within 10 min. The material reached a maximum ultimate compressive strength of 8.20 ± 0.95 MPa, similar to trabecular bone. The material was found to be biocompatible and osteoconductive in vivo out to 26 weeks, with new bone formation and normal bone architecture observed at 6 weeks, as demonstrated by histological evaluation, microcomputed tomography, and radiographic evaluation.

CONCLUSIONS

These findings show that the material properties and performance are well suited for minimally invasive percutaneous delivery applications.

Biological and mechanical performance and degradation characteristics of calcium phosphate cements in large animals and humans

Calcium phosphate cements (CPCs) have been used to treat bone defects and support bone regeneration because of their good biocompatibility and osteointegrative behavior. Since their introduction in the 1980s, remarkable clinical success has been achieved with these biomaterials, because they offer the unique feature of being moldable and even injectable into implant sites, where they harden through a low-temperature setting reaction. However, despite decades of research efforts, two major limitations concerning their biological and mechanical performance hamper a broader clinical use. Firstly, achieving a degradation rate that is well adjusted to the dynamics of bone formation remains a challenging issue. While apatite-forming CPCs frequently remain for years at the implant site without major signs of degradation, brushite-forming CPCs are considered to degrade to a greater extent. However, the latter tend to convert into lower soluble phases under physiological conditions, which makes their degradation behavior rather unpredictable. Secondly, CPCs exhibit insufficient mechanical properties for load bearing applications because of their inherent brittleness. This review places an emphasis on these limitations and provides an overview of studies that have investigated the biological and biomechanical performance as well as the degradation characteristics of different CPCs after implantation into trabecular bone. We reviewed studies performed in large animals, because they mimic human bone physiology more closely in terms of bone metabolism and mechanical loading conditions compared with small laboratory animals. We compared the results of these studies with clinical trials that have dealt with the degradation behavior of CPCs after vertebroplasty and kyphoplasty.

Weight Discharge in Postoperative of Plateau Fracture Tibialis: Systematic Review of Literature

Tibial plateau fractures are a risk to the functional integrity of the knee, affecting the axial alignment and capable of leading to pain and disability of the individual. Early weight bearing and joint mobilization can prevent these functional deficits. the goal of the present study was to conduct a systematic review of the literature about studies that quote the beginning, evolution, and progression criteria for weight-bearing in postoperative period of tibial plateau fractures. We selected articles published in the last 12 years, in Portuguese and English, that described the time of onset and progression of weight-bearing, considering the severity of the fracture. Thirty-six articles were selected. There is no consensus in the literature as to the beginning and evolution of weight-bearing in the postoperative period of tibial plateau fractures; however, a relationship between the severity of the fracture and the fixation method has been observed.

Composite Xenohybrid Bovine Bone-Derived Scaffold as Bone Substitute for the Treatment of Tibial Plateau Fractures

Introduction: Tibial plateau fractures represent a common challenge for orthopaedic surgeons, sometimes representing complex cases to manage, where augmentation using bone grafts is required for stabilisation. Autologous iliac bone graft (AIBG) is the current gold standard for bone grafting. In order to overcome limitations related to the procedure, alternative strategies, like allogenic and xenogeneic bone substitutes have been investigated. Here, within the framework of an observational clinical study, we report clinical and radiological outcomes of patients treated for tibial plateau fractures with a composite xenohybrid bone graft, aiming at assessing clinical and radiological outcomes. Materials and Methods: We performed a cohort retrospective study of patients treated for tibial plateau fractures from May 2017 to January 2018. Thirty-four patients, i.e. 100% of those having received the bone graft under investigation for tibial plateaux fracture treatment, met the inclusion criteria and were enrolled in the study. Patients were assessed at 2 weeks, and then at a 1-, 3-, and 6-months, and 1-year follow-up. At each evaluation patients filled a visual analogue scale (VAS) for the level of pain during the day life activities and underwent physical exam and anteroposterior and lateral projection radiographs of the knee. At 1 year the Tegner Lysholm Scoring Scale, International Knee Document Committee 2000 (IKDC 2000), and Short Form (36) Health Survey (SF-36) were administered. Results: At 1-year, mean VAS decreased from 6.33 ± 1.40 to 1 ± 0.79 (P < 0.0001); Tegner Lysholm Scoring Scale was 89 ± 4.10 and mean IKDC 2000 was 78.67 ± 3.31. No infections, neurovascular complications or adverse effects related to implants were reported during the clinical exams at follow-up. Mean ROM was 124 ± 6°. Radiographs did not show defects of consolidation or progressive post-surgical subsidence and demonstrated a good grade of integration of the implant. Conclusions: Clinical and radiological outcomes, and scores of questionnaires, were good. The xenograft has demonstrated to be a safe biomaterial, with satisfactory mechanical and biological performances in the mid-term period. It also showed a high grade of osteointegration and remodelling.

Tibial plateau fracture management: ARIF versus ORIF - clinical and radiological comparison

INTRODUCTION

Arthroscopy has enabled minimally invasive procedures to be developed to treat tibial plateau fracture. The aim of the present study was to assess and compare clinical and radiological results between arthroscopically assisted reduction and internal fixation (ARIF) and open reduction and internal fixation (ORIF) procedures. The study hypothesis was that, in selected tibial plateau fractures, ARIF provides (1) clinical results comparable to those of ORIF, and (2) satisfactory reduction and stable fixation.

MATERIAL AND METHOD

A retrospective multicenter study included adult patients with tibial plateau fracture (Schatzker I to III), over the period January 2010 to December 2014, enabling a minimum 2 years' follow-up. Clinical and radiological data (RoM, IKDC, HSS, Lysholm) were collected at 3, 6 and 12 months and at last follow-up. A total of 317 patients (317 fractures), aged 48±14 years (range, 18-82 years) were followed up for 38±23 months (range, 24-90 months), with 77 fractures (24%) in the ARIF group and 240 (76%) in the ORIF group.

RESULTS

Clinically, there were no significant inter-group differences for active flexion, passive or active extension or Lysholm and IKDC scores, with significant differences for HSS (ARIF: 74±29; ORIF: 70±31; p<0.01) and passive flexion (ARIF: 130±19° (range, 80-160°); ORIF: 130±15.965° (range, 60-140°); p<0.05). Radiologically, there were no significant inter-group differences for reduction quality, lower-limb mechanical axis or signs of osteoarthritis. There were no secondary displacements. There were 7 complications (7/77, 9%) in the ARIF group and 18 (18/240, 8%) in the ORIF group, and 6 surgical revisions for early infection (2 ARIF, 4 ORIF), with no significant inter-group differences.

DISCUSSION

The study hypothesis was confirmed: in Schatzker I-III fractures, ARIF provided clinical results comparable to those of ORIF, with satisfactory reduction and stable fixation. ARIF has its place in the treatment of tibial plateau subsidence and/or separation fracture.

LEVEL OF EVIDENCE

III, retrospective comparative study.

Percutaneous Reduction and Internal Fixation for Monocondylar Fractures of Tibial Plateau: A Systematic Review

Instead of extensive dissection of soft tissue around the fracture site, percutaneous techniques have unique advantages in managing displaced fragments, including preservation of soft tissues, less blood loss, lower risk of complications, and earlier functional rehabilitation. However, there are few systematic reviews on the effects of percutaneous reduction and internal fixation (PRIF) for tibial plateau fractures. A systematic search of Cochrane, EMBASE, and MEDLINE databases was performed for all publicly available data in March 2017 regarding the use of PRIF in treating monocondylar tibial plateau fractures. Basic information of included articles, surgical information, clinical outcomes, and concomitant soft tissue injuries were collected for analysis. Finally, a total of 20 articles including 561 patients were retrieved. Traffic accident was the most common cause of injury. Percutaneous techniques using bone tamp reduction were described in all studies. The majority (≥85%) of patients were classified as excellent or good according to clinical and radiological Rasmussen scores. The overall complication rate was 6.6%, with loss of reduction the most frequent complication with an incidence of 2.4%. This systematic review indicated that PRIF was an optimal alternative that physicians should consider for the treatment of monocondylar tibial plateau fractures.

Minimally invasive opening wedge tibia outpatient osteotomy, using screw-to-plate locking technique and a calcium phosphate cement

Medial knee osteoarthritis on angular varus deformity of a lower limb is very common. Open-wedge high tibial osteotomy is a treatment of choice if cartilage is not excessively worn (Allback 1 or 2). The technique based on a plate fixation and the bone defect filled with calcium phosphate cement is thoroughly described. Data at 1, 3, 6 months and 1 year of a 19 cases continuous and prospective series are collected and analysed. Mean age at the time of operation was 55 years. The average preoperative varus deformity was 5° and corrected to an average postoperative valgus of 4° (range 3°-6°). Each control includes the collection of eventual complications, the measurement of health status (quality of life and functional scores) and antero-posterior and lateral X-rays. All osteotomies were considered healed at 6 weeks without any correction loss except one, probably result of a technical error. There was no difference in clinical and functional results between the group and the literature, but the final result occurred earlier in the treatment when the bone defect was filled with either calcium phosphate cement. Faster recovery involved no specific complication and enabled outpatient treatment in a majority of patients.

Characteristics of postoperative weight bearing and management protocols for tibial plateau fractures: Findings from a scoping review

OBJECTIVE

To identify and describe the characteristics of existing practices for postoperative weight bearing and management of tibial plateau fractures (TPFs), identify gaps in the literature, and inform the design of future research.

METHODS

Seven electronic databases and clinical trial registers were searched from inception until November 17th 2016. Studies were included if they reported on the surgical management of TPFs, had a mean follow-up time of ≥1year and provided data on postoperative management protocols. Data were extracted and synthesized according to study demographics, patient characteristics and postoperative management (weight bearing regimes, immobilisation devices, exercises and complications).

RESULTS

124 studies were included involving 5156 patients with TPFs. The mean age across studies was 45.1 years (range 20.8-72; 60% male), with a mean follow-up of 34.9 months (range 12-264). The most frequent fracture types were AO/OTA classification 41-B3 (29.5%) and C3 (25%). The most commonly reported non-weight bearing time after surgery was 4-6 weeks (39% of studies), with a further 4-6 weeks of partial weight bearing (51% of studies), resulting in 9-12 weeks before full weight bearing status was recommended (55% of studies). Loading recommendations for initial weight bearing were most commonly toe-touch/<10kg (28%), 10kg-20kg (33%) and progressive (39%). Time to full weight bearing was positively correlated with the proportion of fractures of AO/OTA type C (r=0.465, p=0.029) and Schatzker type IV-VI (r=0.614, p<0.001). Similar rates of rigid (47%) and hinged braces were reported (58%), most frequently for 3-6 weeks (43% of studies). Complication rates averaged 2% of patients (range 0-26%) for abnormal varus/valgus and 1% (range 0-22%) for non-union or delayed union.

CONCLUSIONS

Postoperative rehabilitation for TPFs most commonly involves significant non-weight bearing time before full weight bearing is recommended at 9-12 weeks. Partial weight bearing protocols and brace use were varied. Type of rehabilitation may be an important factor influencing recovery, with future high quality prospective studies required to determine the impact of different protocols on clinical and radiological outcomes.

Development of Sr-incorporated biphasic calcium phosphate bone cement

To follow the design strategy of traditional biphasic calcium phosphate (BCP) ceramic, in the present study, strontium-doped biphasic calcium phosphate bone cement (Sr-BCPC) composites comprising Sr-β-tricalcium phosphate (TCP)/Sr-hydroxyapatite (HAP) had been prepared for the first time using Sr _x -β-TCP/tetracalcium phosphate (TTCP) as a cement powder and diluted phosphoric acid as a cement liquid. The phase composition, setting time, compressive strength, washout resistance, in vitro degradation rate, microstructure evolutions, hydration dynamics and cytotoxicity of Sr-BCPC at various Sr contents were intensively investigated. It was found that the final cement product was composed of entangled Sr-HAP nano-needles and cobblestone-like Sr-β-TCP sub-micron particles, and the weight percentages in the final cement product after hydration in simulated body fluid for 24 h were in the ranges of 60 wt%-70 wt% Sr-HAP and 30 wt%-40 wt% Sr-β-TCP, respectively. Sr and the concentration of Sr exhibit significant effects on the phase compositions, compressive strength, setting time, in vitro degradation rate and cytotoxicity of the biphasic bone cement. In particular, the degradation rate increased considerably with the increase of the Sr-β-TCP phase. It is anticipated that the introduction of the 'biphasic' design into calcium phosphate bone cements is an effective strategy to improve their degradation properties.

Arthroscopy Assisted Balloon Osteoplasty of a Tibia Plateau Depression Fracture: A Case Report

Context:

A clinical case of a tibia plateau fracture is presented which was treated with balloon osteoplasty and arthroscopy guidance. Balloon Tibioplasty has been shown to be a very useful method for the management of tibial plateau fractures. The use of calcium phosphate has been described in the literature for management and restoration of bone defects in tibial plateau fractures.

Case Report:

A 45-years-old Caucasian woman was presented after a fall from a ladder. The patient sustained a lateral tibia plateau fracture which was classified as Shatzker type III (AO 41-B2) with posterolateral depression of the joint surface. Surgical treatment was applied using a minimal approach which included percutaneous reduction of the fracture under arthroscopy and fluoroscopy guidance. The bone defect was filled with calcium phosphate via injection. The clinical outcome at the 6, 12 and 24 weeks was excellent with full-range of motion of the knee joint.

Conclusion:

Arthroscopy assisted balloon osteoplasty seems to be a safe and effective method for the treatment of depressed tibia plateau fractures. Further study is needed for the proper evidence based use and application of this method.

Arthroscopy-assisted surgery for tibial plateau fractures

PURPOSE

This study aimed to summarize the recent clinical outcomes of patients undergoing arthroscopy-assisted reduction and internal fixation (ARIF) for tibial plateau fractures.

METHODS

A systematic electronic search of the PubMed and Cochrane databases was performed in January 2014. All English-language clinical studies on tibial plateau fractures treated with ARIF that were published after January 1, 2000 were eligible for inclusion. Basic information related to the surgery was collected.

RESULTS

The search criteria initially identified 141 articles, and 19 studies were included in this systematic review. There were 2 retrospective comparative studies, 16 case series studies, and one clinical series based on a technique note. There were a total of 609 patients in this systematic review, with a mean follow-up time of 52.5 months. The most common fracture types were Schatzker types II and III. Concomitant injuries were common: 42.2% of the patients had meniscal injuries, and 21.3% had anterior cruciate ligament (ACL) injuries. In addition, the status of 90.5% of the patients was classified as good or excellent according to the clinical Rasmussen scoring system, and 90.9% of the patients were satisfied with the treatment. Only 6 severe complications were reported, including one case of compartment syndrome.

CONCLUSIONS

ARIF is a reliable, effective, and safe method for the treatment of tibial plateau fractures, especially when they present with concomitant injuries.

LEVEL OF EVIDENCE

Level IV, systematic review of Level III and Level IV studies.

Reduction and Stabilization of Depressed Articular Tibial Plateau Fractures: Comparison of Inflatable and Conventional Bone Tamps: Study of a Cadaver Model

BACKGROUND

Restoration of articular congruity and mechanical integrity of subchondral bone are important surgical goals of the treatment of intra-articular fractures. The purpose of this study was to compare the reduction quality and biomechanical integrity between cadaveric intra-articular tibial plateau fractures reduced with an inflatable bone tamp and contralateral fractures reduced with a series of cylindrical conventional metal bone tamps.

METHODS

A standardized lateral tibial plateau split-depression fracture was created in each leg of fourteen pairs of cadaver legs. In each pair, the fracture on one side was reduced under fluoroscopy with use of an inflatable bone tamp and the fracture on the contralateral, control side was reduced with conventional bone tamps and a mallet. Any residual bone defects were filled with calcium phosphate bone-void filler. The constructs were stabilized with a lateral tibial plateau buttress plate. Each articular reduction was qualitatively graded by blinded observers using fluoroscopic images, three-dimensional computed tomography (CT) scans, and visual inspection of the articular surface. Quantitative volumetric analysis was performed to calculate under-reduction, over-reduction, and total malreduction volumes. Each reduced fracture was cyclically loaded and then statically loaded to failure under axial compression, and the strength and stiffness of the constructs were compared between sides.

RESULTS

The majority (eleven) of the fourteen fractures reduced with the inflatable bone tamp were rated as having a better reduction than the contralateral fracture reduced with the conventional bone tamps. The median over-reduction and malreduction in the inflatable-tamp group (7% and 21.6%, respectively) were significantly less than those in the conventional-tamp group (19.2% and 47.1%), although the median under-reduction (6.2% in the inflatable-tamp group and 9.6% in the conventional-tamp group) did not differ significantly between groups. The fractures reduced with the inflatable tamp displaced less during cyclic loading than those reduced with the conventional tamp. Median static stiffness and yield load were also significantly higher in the inflatable-tamp group (880 N/mm and 704 N) than in the conventional-tamp group (717 N/mm and 641 N).

CONCLUSIONS

As compared with contralateral control fractures treated with conventional bone tamps, fractures treated with an inflatable bone tamp had qualitatively and quantitatively better reduction, typically resulting in a smoother articular surface with less residual defect volume. Fractures reduced with an inflatable bone tamp exhibited less subsidence during cyclic loading and greater stiffness under static loading compared with those treated with conventional bone tamps.

CLINICAL RELEVANCE

Using an inflatable bone tamp in association with calcium phosphate bone-void filler to reduce and maintain reduction of an articular fracture may help in achieving the surgical goal of a more anatomic reduction with better resistance to subsidence.

Factors predicting the development of early osteoarthritis following lateral tibial plateau fractures: mid-term clinical and radiographic outcomes of 73 operatively treated patients

Background and Aims:

The indications for operative treatment of lateral tibial plateau fractures are still controversial. The objective of this study was to determine whether residual articular surface depression and valgus malalignment of plated lateral tibial plateau fractures at medium-term follow-up affect the clinical and radiographic outcomes.

Material and Methods:

A chart review of patients with operatively treated (AO type B3.1) tibial plateau fractures that were admitted to our level I trauma center between 2002 and 2008 was performed. Out of 123 patients, 73 were available to participate in a clinical and radiographic follow-up examination. The mean follow-up time was 54 months. Patients were clinically assessed and completed the Lysholm knee score and Western Ontario and McMaster Universities Osteoarthritis Index. Maximal articular surface depression, radiological mechanical axis, and degree of posttraumatic osteoarthritis were evaluated from standing radiographs.

Results:

Patients with valgus malalignment of 5° or greater at follow-up developed more advanced osteoarthritis (Kellgren–Lawrence grade 3–4) than patients with a normal mechanical axis (p = 0.006). Similarly, patients with articular depression greater than 2 mm at follow-up also developed more advanced osteoarthritis compared to patients with a depression of 2 mm or less (p = 0.001). The degree of valgus malalignment or articular depression had no effect on the Western Ontario and McMaster Universities Osteoarthritis Index or Lysholm scores.

Conclusions:

The postoperative articular congruity and normal mechanical axis of the lower leg after plate fixation in lateral tibial plateau fractures seem to have a role in prevention of posttraumatic osteoarthritis but does not appear to predict clinical outcome at medium-term follow-up. The role of initial dislocation and associated cartilage damage in the development of osteoarthritis following these fractures is still unknown.

Self-setting calcium orthophosphate formulations

In early 1980s, researchers discovered self-setting calcium orthophosphate cements, which are bioactive and biodegradable grafting bioceramics in the form of a powder and a liquid. After mixing, both phases form pastes, which set and harden forming either a non-stoichiometric calcium deficient hydroxyapatite or brushite. Since both of them are remarkably biocompartible, bioresorbable and osteoconductive, self-setting calcium orthophosphate formulations appear to be promising bioceramics for bone grafting. Furthermore, such formulations possess excellent molding capabilities, easy manipulation and nearly perfect adaptation to the complex shapes of bone defects, followed by gradual bioresorption and new bone formation. In addition, reinforced formulations have been introduced, which might be described as calcium orthophosphate concretes. The discovery of self-setting properties opened up a new era in the medical application of calcium orthophosphates and many commercial trademarks have been introduced as a result. Currently such formulations are widely used as synthetic bone grafts, with several advantages, such as pourability and injectability. Moreover, their low-temperature setting reactions and intrinsic porosity allow loading by drugs, biomolecules and even cells for tissue engineering purposes. In this review, an insight into the self-setting calcium orthophosphate formulations, as excellent bioceramics suitable for both dental and bone grafting applications, has been provided.

Risk analysis in tibial plateau fractures: association between severity, treatment and clinical outcome

Our retrospective study analyzes efficacy of treatment techniques we used for the reduction of tibial plateau fracture. A sample of 67 individuals is evaluated, 50 males and 17 females, and treated for a tibial plateau fracture from December 2003 to June 2008. The mean age is 46 (range 22-72). 35 patients were treated with cannulated screws alone, 21 were treated with plates alone, and 11 were treated with both plates and bone substitutes. All patients were clinically and radiographically followed up for an average time of 36.4 months (SD = 17.4; range 24-72). Data about patients sourced from the analysis of SF36, WOMAC and the Rasmussen score. Patients were divided into 4 groups and 2 subgroups, according to the synthesis method used and the severity of the fracture. The control group includes the patients diagnosed with a low-energy fracture treated with screws alone. The median of the total score of Rasmussen functional grading system resulted to be equal to 26; compared with the control group, there is strong relationship between the use of plates alone and the risk of obtaining a clinically less effective result (O.R. = 5.48; p = 0.003) even more when comparing Schatzker type IV, V, and VI (O.R. = 13; p = 0.0073). Radiographic evaluation shows less efficacy of bone substitute to reduce articular step-off. With regard to the SF36, patients treated with plate alone have been awarded the lowest score. The treatment of the most severe fractures of tibial plateau by means of internal fixation with plates can be improved with the use of bone substitutes.

Use of bone graft substitutes in the management of tibial plateau fractures

The current available evidence for the use of bone graft substitutes in the management of subchondral bone defects associated with tibial plateau fractures as to their efficiency and safety has been collected following a literature review of the Ovid MEDLINE (1948-Present) and EMBASE (1980-Present). Nineteen studies were analysed reporting on 672 patients (674 fractures), with a mean age of 50.35 years (range 15-89), and a gender ratio of 3/2 males/females. The graft substitutes evaluated in the included studies were calcium phosphate cement, hydroxyapatite granules, calcium sulphate, bioactive glass, tricalcium phosphate, demineralised bone matrix, allografts, and xenograft. Fracture healing was uneventful in over 90% of the cases over a variant period of time. Besides two studies reporting on injectable calcium phosphate cement excellent incorporation was reported within 6 to 36 months post-surgery. No correlation was made by any of the authors between poor incorporation/resorption and adverse functional or radiological outcome. Secondary collapse of the knee joint surface ≥ 2 mm was reported in 8.6% in the biological substitutes (allograft, DBM, and xenograft), 5.4% in the hydroxyapatite, 3.7% in the calcium phosphate cement, and 11.1% in the calcium sulphate cases. The recorded incidence of primary surgical site and donor site infection (3.6%) was not statistically significant different, however donor site-related pain was reported up to 12 months following autologous iliac bone graft (AIBG) harvest. Shorter total operative time, greater tolerance of early weight bearing, improved early functional outcomes within the first year post-surgery was also recorded in the studies reporting on the use of injectable calcium phosphate cement (Norian SRS). Despite a lack of good quality randomised control trials, there is arguably sufficient evidence supporting the use of bone graft substitutes at the clinical setting of depressed plateau fractures.

Calcium phosphate cements as drug delivery materials

Calcium phosphate cements are used as synthetic bone grafts, with several advantages, such as their osteoconductivity and injectability. Moreover, their low-temperature setting reaction and intrinsic porosity allow for the incorporation of drugs and active principles in the material. It is the aim of the present work to: a) provide an overview of the different approaches taken in the application of calcium phosphate cements for drug delivery in the skeletal system, and b) identify the most significant achievements. The drugs or active principles associated to calcium phosphate cements are classified in three groups, i) low molecular weight drugs; ii) high molecular weight biomolecules; and iii) ions.

An approximate model for cancellous bone screw fixation

This paper presents a finite element (FE) model to identify parameters that affect the performance of an improved cancellous bone screw fixation technique, and hence potentially improve fracture treatment. In cancellous bone of low apparent density, it can be difficult to achieve adequate screw fixation and hence provide stable fracture fixation that enables bone healing. Data from predictive FE models indicate that cements can have a significant potential to improve screw holding power in cancellous bone. These FE models are used to demonstrate the key parameters that determine pull-out strength in a variety of screw, bone and cement set-ups, and to compare the effectiveness of different configurations. The paper concludes that significant advantages, up to an order of magnitude, in screw pull-out strength in cancellous bone might be gained by the appropriate use of a currently approved calcium phosphate cement.

The use of bone graft substitutes in large cancellous voids: any specific needs?

Bone graft is the second most common transplantation tissue, with blood being by far the commonest. Autograft is considered ideal for grafting procedures, providing osteoinductive growth factors, osteogenic cells and an osteoconductive scaffold. Limitations, however, exist regarding donor site morbidity and graft availability. Allograft on the other hand poses the risk of disease transmission. Synthetic graft substitutes lack osteoinductive or osteogenic properties. Composite grafts combine scaffolding properties with biological elements to stimulate cell proliferation and differentiation and eventually osteogenesis. We present here an overview of bone graft substitutes available for clinical application in large cancellous voids.

Tibial plateau fractures: A review

Tibial plateau fractures are uncommon injuries of the proximal tibia which vary in severity from minimally displaced stable injuries to high energy complex fractures with significant articular and metaphyseal comminution and severe associated soft tissue injuries. Following initial assessment and appropriate investigation a number of management options are available to the treating surgeon. We discuss the presentation, initial management and investigation as well as outlining the various treatment options with an emphasis on operative treatment. We further discuss the common complications and outcomes following tibial plateau fracture.

Bioactive glass granules: a suitable bone substitute material in the operative treatment of depressed lateral tibial plateau fractures: a prospective, randomized 1 year follow-up study

Purpose of this study was to compare bioactive glass and autogenous bone as a bone substitute material in tibial plateau fractures. We designed a prospective, randomized study consisting of 25 consecutive operatively treated patients with depressed unilateral tibial comminuted plateau fracture (AO classification 41 B2 and B3).14 patients (7 females, 7 males, mean age 57 years, range 25-82) were randomized in the bioglass group (BG) and 11 patients (6 females, 5 males, mean age 50 years, range 31-82) served as autogenous bone control group (AB). Clinical examination of the patients was performed at 3 and 12 months, patients' subjective and functional results were evaluated at 12 months. Radiological analysis was performed preoperatively, immediately postoperatively and at 3 and 12 months. The postoperative redepression for both studied groups was 1 mm until 3 months and remained unchanged at 12 months. No differences were identified in the subjective evaluation, functional tests and clinical examination between the two groups during 1 year follow-up. We conclude that bioactive glass granules can be clinically used as filler material instead of autogenous bone in the lateral tibial plateau compression fractures.

Microstructure and biomechanical characteristics of bone substitutes for trauma and orthopaedic surgery

BACKGROUND

Many (artificial) bone substitute materials are currently available for use in orthopaedic trauma surgery. Objective data on their biological and biomechanical characteristics, which determine their clinical application, is mostly lacking. The aim of this study was to investigate structural and in vitro mechanical properties of nine bone substitute cements registered for use in orthopaedic trauma surgery in the Netherlands.

METHODS

Seven calcium phosphate cements (BoneSource®, Calcibon®, ChronOS®, Eurobone®, HydroSet™, Norian SRS®, and Ostim®), one calcium sulphate cement (MIIG® X3), and one bioactive glass cement (Cortoss®) were tested. Structural characteristics were measured by micro-CT scanning. Compression strength and stiffness were determined following unconfined compression tests.

RESULTS

Each bone substitute had unique characteristics. Mean total porosity ranged from 53% (Ostim®) to 0.5% (Norian SRS®). Mean pore size exceeded 100 μm only in Eurobone® and Cortoss® (162.2 ± 107.1 μm and 148.4 ± 70.6 μm, respectively). However, 230 μm pores were found in Calcibon®, Norian SRS®, HydroSet™, and MIIG® X3. Connectivity density ranged from 27/cm3 for HydroSet™ to 0.03/cm3 for Calcibon®. The ultimate compression strength was highest in Cortoss® (47.32 MPa) and lowest in Ostim® (0.24 MPa). Young's Modulus was highest in Calcibon® (790 MPa) and lowest in Ostim® (6 MPa).

CONCLUSIONS

The bone substitutes tested display a wide range in structural properties and compression strength, indicating that they will be suitable for different clinical indications. The data outlined here will help surgeons to select the most suitable products currently available for specific clinical indications.

Bone substitutes in the Netherlands - a systematic literature review

Autologous bone grafting is currently considered as the gold standard to restore bone defects. However, clinical benefit is not guaranteed and there is an associated 8-39% complication rate. This has resulted in the development of alternative (synthetic) bone substitutes. The aim of this systematic literature review was to provide a comprehensive overview of literature data of bone substitutes registered in the Netherlands for use in trauma and orthopedic surgery. Brand names of selected products were used as search terms in three available databases: Embase, PubMed and Cochrane. Manuscripts written in English, German or Dutch that reported on structural, biological or biomechanical properties of the pure product or on its use in trauma and orthopedic surgery were included. The primary search resulted in 475 manuscripts from PubMed, 653 from Embase and 10 from Cochrane. Of these, 218 met the final inclusion criteria. Of each product, structural, biological and biomechanical characteristics as well as their clinical indications in trauma and orthopedic surgery are provided. All included products possess osteoconductive properties but differ in resorption time and biomechanical properties. They have been used for a wide range of clinical applications; however, the overall level of clinical evidence is low. The requirements of an optimal bone substitute are related to the size and location of the defect. Calcium phosphate grafts have been used for most trauma and orthopedic surgery procedures. Calcium sulphates were mainly used to restore bone defects after tumour resection surgery but offer minimal structural support. Bioactive glass remains a potential alternative; however, its use has only been studied to a limited extent.

Percutaneous cement augmentation for the treatment of depression fractures of the tibial plateau

The management of insufficiency fractures of the tibial plateau in osteoporotic patients can be very challenging, since it is difficult to achieve a stable fixation, an essential condition for the patients' early mobilization. We present a minimally invasive technique for the treatment of proximal tibial plateau fractures, "tibiaplasty", using percutaneous polymethylmethacrylate augmentation. Five osteoporotic patients (7 fractures) with a non-traumatic insufficiency tibial plateau fracture were treated with this technique at the authors' institution from 2006 to 2008. The patients' median age was 79 (range 62-88) years. The intervention was performed percutaneously under general or spinal anesthesia; after the intervention, immediate full weight bearing was allowed. The technique was feasible in all patients and no complications related to the intervention were observed. All patients reported a relevant reduction in pain, were able to mobilize with full weight bearing and would undergo the operation again. No secondary loss of reduction or progression of arthrosis was observed in radiological controls; no revision surgery was required. Our initial results indicate that tibiaplasty is a good treatment option for the management of insufficiency in tibial plateau fractures in osteoporotic patients. The technique is minimally invasive, safe and allows immediate mobilization without restrictions. In our group of patients, we found excellent early to mid-term results.

Peri-articular fractures of the knee: an update on current issues

Peri-articular fractures of the knee in the young and elderly pose several management dilemmas. Over the last decade enormous interest has been generated in various fixation modalities, none proving to be an ideal stabilisation method. The problem is compounded by a lack of well-designed studies comparing various treatment options. In this article, the issues surrounding the diagnostic and management strategies of peri-articular fractures of the knee are discussed.

Calcium phosphate cement enhances primary stability of open-wedge high-tibial osteotomies

We investigated if injectable calcium phosphate cement improves primary stability in open-wedge high-tibial osteotomy. A 10 mm open-wedge osteotomy was performed on eight pairs of preserved cadaver tibiae and seven pairs of composite (Sawbone) left tibiae. Osteosynthesis was performed with the Dynafix plate system. The gap resulting from surgery either was filled with 15 g injectable calcium phosphate cement in half the bones or was left untreated. The composite tibiae were loaded at a ramp speed of 20 mm/min up to 20 kN. The cadaver tibiae were exposed to 100 cycles with a maximum compressive force of 2,250 N. After 100 cycles of loading with 2,250 N, the final loaded displacement was 1.2 mm for the cadaver tibiae treated with injectable calcium phosphate cement as compared with 3.6 mm for the empty defects (P = 0.028). All the seven empty defect composite specimens failed prior to 20 kN (median 2.8 kN) as compared with five of the injectable calcium phosphate cement specimens (median 17 kN) (P = 0.005). The injection of injectable calcium phosphate cement following open-wedge osteotomy of the proximal tibia increases the initial stability of the bone as measured by load-to-failure and displacement after cyclic loading. Clinical studies are ongoing to investigate whether injectable calcium phosphate cement also has clinical advantage on wedge healing and stability.

The use of beta-TCP in the surgical treatment of tibial plateau fractures

The objective of this study was to evaluate the outcome of using beta-TCP in the treatment of depression tibial plateau fractures. A total of 124 patients with depression tibial fractures were included in this study and followed for a minimum of 12 months. All the cases were treated with open reduction and internal fixation, and grafted with beta-TCP ceramic. The clinical and radiological outcomes were assessed using Hospital for Special Surgery (HSS) score of knee and Rasmussen score during the follow-up. No obvious redisplacement was found at the follow-up assessment. Most of the patients had excellent HSS score and Rasmussen clinical score. Bone healing was noted in all fractures and Schatzker II-type fractures had the best functional outcome. The results suggested that using beta-TCP combined with open reduction and rigid internal fixation was an effective treatment for depression fractures of the tibial plateau.

Effect of rhBMP-2 on tibial plateau fractures in a canine model

This study was to determine the efficacy of recombinant human bone morphogenetic protien-2 (rhBMP-2)/calcium phosphate matrix (CPX) paste to accelerate healing in a canine articular fracture model with associated subchondral defect. rhBMP-2/CPX (BMP), CPX alone (CPX) or autogenous bone graft (ABG) was administered to a canine articular tibial plateau osteotomy with a subchondral defect in each of 21 female dogs. The unoperated contralateral limbs served as controls. Ground reaction forces, synovial fluid, radiographic changes, mechanical testing, bone density, and histology of bone and synovium were analyzed at 6 weeks after surgery. Radiographic analysis demonstrated that the BMP and CPX groups showed improved bony healing compared to the ABG group at week 6. Histomorphometric analysis demonstrated that the BMP group had significantly increased trabecular bone volume compared to the CPX and ABG groups. Mechanical testing revealed that the BMP group had significantly greater maximum failure loads than the ABG group. Histological analysis demonstrated that the BMP group had significantly less sub-synovial inflammation than CPX group. This study demonstrated that rhBMP-2/CPX accelerated healing of articular fractures with subchondral defect compared to ABG in most of the parameters evaluated, and had less subsynovial inflammation than the CPX alone in a canine model.

Calcium Orthophosphate Cements and Concretes

In early 1980s, researchers discovered self-setting calcium orthophosphate cements, which are a bioactive and biodegradable grafting material in the form of a powder and a liquid. Both phases form after mixing a viscous paste that after being implanted, sets and hardens within the body as either a non-stoichiometric calcium deficient hydroxyapatite (CDHA) or brushite, sometimes blended with unreacted particles and other phases. As both CDHA and brushite are remarkably biocompartible and bioresorbable (therefore, in vivo they can be replaced with newly forming bone), calcium orthophosphate cements represent a good correction technique for non-weight-bearing bone fractures or defects and appear to be very promising materials for bone grafting applications. Besides, these cements possess an excellent osteoconductivity, molding capabilities and easy manipulation. Furthermore, reinforced cement formulations are available, which in a certain sense might be described as calcium orthophosphate concretes. The concepts established by calcium orthophosphate cement pioneers in the early 1980s were used as a platform to initiate a new generation of bone substitute materials for commercialization. Since then, advances have been made in the composition, performance and manufacturing; several beneficial formulations have already been introduced as a result. Many other compositions are in experimental stages. In this review, an insight into calcium orthophosphate cements and concretes, as excellent biomaterials suitable for both dental and bone grafting application, has been provided.

Injectable bioactive calcium-magnesium phosphate cement for bone regeneration

Novel injectable and degradable calcium-magnesium phosphate cement (CMPC) with rapid-setting characteristic was developed by the introduction of magnesium phosphate cement (MPC) into calcium phosphate cement (CPC). The calcium-magnesium phosphate cement prepared under the optimum P/L ratio exhibited good injectability and desired workability. It could set within 10 min at 37 degrees C in 100% relative humidity and the compressive strength could reach 47 MPa after setting for 48 h, indicating that the prepared cement has relatively high initial mechanical strength. The results of in vitro degradation experiments demonstrated the good degradability of the injectable CMPC, and its degradation rate occurred significantly faster than that of pure CPC in simulated body fluid (SBF) solution. It can be concluded that the novel injectable calcium-magnesium phosphate cement is highly promising for a wide variety of clinical applications, especially for the development of minimally invasive techniques.

Severely comminuted bicondylar tibial plateau fractures in geriatric patients: a report of 2 cases treated with open reduction and postoperative external fixation

We present 2 cases of C3-type fractures of the tibial plateau in geriatric patients. Our treatment concept--in particular the use of postoperative external fixation--is not yet described in the recent literature and includes initial external fixation, internal fixation after soft tissue consolidation using a median incision, filling of the metaphyseal comminution zone with allogenic cancellous bone obtained from a femoral head, anteromedial and anterolateral fixed-angle double plating, and external fixation postoperatively until osseous healing. The described treatment plan does not provide a valid alternative for the treatment of bicondylar fractures in younger patients. It may be an option for the treatment of C3-type fractures in geriatric patients only.

Evaluation of a novel nanocrystalline hydroxyapatite paste and a solid hydroxyapatite ceramic for the treatment of critical size bone defects (CSD) in rabbits

The purpose of our study was to test the effectiveness of Ostim nanocrystalline hydroxyapatite paste and Cerabone ceramic by treating a critical size bone defect (CSD) on the right foreleg of a white New Zealand rabbit. Evaluation was carried out by comparing four groups each with a different CSD filling: an only OSTIM bone filling, an only Cerabone filling, an OSTIM-Cerabone combination, and a control group with no filling of the CSD. The results of this study display a rapid and uniform bone ingrowth following the CSD filling with Ostim. The histological and histomorphometrical data have shown similarly excellent results for both the Ostim and Cerabone-Ostim groups. The control group faired poorly in comparison, as three cases of non-union were observed and none of the defects were totally refilled with fresh bone within 60 days. The successful bone healing with osseous consolidation verifies the importance of the nanocrystalline hydroxyapatite in the treatment of metaphyseal osseous volume defects in the metaphyseal spongiosa.

Controllable release of salmon-calcitonin in injectable calcium phosphate cement modified by chitosan oligosaccharide and collagen polypeptide

The aim of this research is to study the effect of the controlled releasing character of the salmon calcitonin (S-CT) loaded injectable calcium phosphate cement (CPC) modified by adding organic phase, chitosan oligosaccharide (CO) and collagen polypeptide (CP). The uniform design was used to determine the basic formulation with suitable injectable time for clinical application, and then the changes of the physical characters, the controlled releasing character of the modified CPC along with the ratio of the organic phase were also evaluated in vitro. The surface morphous of the modified CPC been implanted in the abdominal cavity or soaked into the serum of rat was also observed by scanning electron microscope (SEM). The result shows that a suitable formulation of modified CPC could be got, and the injectable time is 12 min, the compressive strength is 12 MPa, and the final setting time is 40 min. Comparing with the CPC without organic phase, the releasing rate of S-CT would increase along with the increase of the organic phase after 7th day. Therefore, a novel S-CT loaded bioactive injectable CPC for treating osteoporosis induced bone defect was obtained, and the release of the containing S-CT was controlled easily through adjusting the ratio of CO and CP.

Synthetic bone scaffolds and fracture repair

Synthetic scaffolding has been used in the treatment of bone defects and fractures for over 100 years. They remain a critical tool in the treatment of large-volume bone defects, and their role as potential substitues for human bone graft continues to expand. Various materials are used commercially to produce osteoconductive scaffolds including ceramics (both bioactive and bioinert) and select polymers, all of which offer distinct advantages and dissadvantages. While currently used principally as osteoconductive conduits for growth, the role of bone-graft substitues in fracture treatment is likely to change, as biomaterial research moves towards utilizing current and future scaffold materials as delivery systems for biologic fracture treatments.

Treatment of a solitary calcaneal cyst with endoscopic curettage and percutaneous injection of calcium phosphate cement

We report the case of a 35-year-old man who presented with pain in the right heel. Plain radiographs and computerized tomography revealed a solitary cyst of the calcaneus. Endoscopic curettage of the lesion and endoscopically assisted filling of the lesion with calcium phosphate bone cement injected percutaneously were performed. After 12 months, no recurrence was noted and the patient was symptom free.

Intra-articular calcium phosphate cement: Its fate and impact on joint tissues in a rabbit model

Clinical application of injectable ceramic cement in comminuted fractures revealed penetration of the viscous paste into the joint space. Not much is known on the fate of this cement and its influence on articular tissues. The purpose of this experimental study was to assess these unknown alterations of joint tissues after intra-articular injection of cement in a rabbit knee. Observation periods were from 1 week up to 24 months, with three rabbits per group. Norian SRS cement was injected into one knee joint, the contralateral side receiving the same volume of Ringers' solution. Light microscopic evaluation of histologic sections was performed, investigating the appearance of the cement, inflammatory reactions, and degenerative changes of the articular surface. No signs of pronounced acute or chronic inflammation were visible. The injected cement was mainly found as a single particle, anterior to the cruciate ligaments. It became surrounded by synovial tissues within 4 weeks and showed signs of superficial resorption. In some specimens, bone formation was seen around the cement. Degeneration of the articular surface showed no differences between experimental and control side, and no changes over time became apparent. No major degenerative changes were induced by the injected cement. The prolonged presence of cement still seems to make it advisable to remove radiologically visible amounts from the joint space.

Mechanical evaluation of implanted calcium phosphate cement incorporated with PLGA microparticles

In this study, the mechanical properties of an implanted calcium phosphate (CaP) cement incorporated with 20wt% poly (dl-lactic-co-glycolic acid) (PLGA) microparticles were investigated in a rat cranial defect. After 2, 4 and 8 weeks of implantation, implants were evaluated mechanically (push-out test) and morphologically (Scanning Electron Microscopy (SEM) and histology). The results of the push-out test showed that after 2 weeks the shear strength of the implants was 0.44+/-0.44MPa (average+/-sd), which increased to 1.34+/-1.05MPa at 4 weeks and finally resulted in 2.60+/-2.78MPa at 8 weeks. SEM examination showed a fracture plane at the bone-cement interface at 2 weeks, while the 4- and 8-week specimens created a fracture plane into the CaP/PLGA composites, indicating an increased strength of the bone-cement interface. Histological evaluation revealed that the two weeks implantation period resulted in minimal bone ingrowth, while at 4 weeks of implantation the peripheral PLGA microparticles were degraded and replaced by deposition of newly formed bone. Finally, after 8 weeks of implantation the degradation of the PLGA microparticles was almost completed, which was observed by the bone ingrowth throughout the CaP/PLGA composites. On basis of our results, we conclude that the shear strength of the bone-cement interface increased over time due to bone ingrowth into the CaP/PLGA composites. Although the bone-cement contact could be optimized with an injectable CaP cement to enhance bone ingrowth, still the mechanical properties of the composites after 8 weeks of implantation are insufficient for load-bearing purposes.

The syringe technique for minimally invasive bone grafting

Standard techniques of bone grafting for nonunion involve extensive dissection of the soft tissues surrounding the nonunion site to gain exposure and facilitate placement of the graft. Successful minimally invasive grafting has been described; however, it can involve difficulties in graft placement or require the use of advanced, expensive technical equipment. We describe a simple, inexpensive technique in which the distal end of a standard syringe is trimmed to provide a conduit for minimally invasive delivery of bone graft material. Three illustrative case reports are discussed in which this technique achieved successful union without operative morbidity.