Repair of five distal radius fractures with an investigational cancellous bone cement: a preliminary report

A Critical Assessment of the Most Cited Papers on Distal Radius Fractures

This article reviews the impact of the most cited works on distal radius fractures. Judged by the most cited works in this field, distal radius fracture research has followed other paradigm shifts in the history of science. Landmark papers showed that restoring premorbid anatomy led to better outcomes, and a plurality of fixation strategies emerged. A breakthrough in technology came with volar plating, and the new paradigm emerged: precise anatomic reduction is achieved typically with volar plates, unless fragment-specific approaches are needed. This paradigm is being challenged as the association among malunion, arthritis, and function continues to be understood. The best treatment of distal radius fractures in the elderly has also evolved through time.

Clinical impact of high-profile animal-based research reported in the UK national press

OBJECTIVES

We evaluated animal-based biomedical 'breakthroughs' reported in the UK national press in 1995 (25 years prior to the conclusion of this study). Based on evidence of overspeculative reporting of biomedical research in other areas (eg, press releases and scientific papers), we specifically examined animal research in the media, asking, 'In a given year, what proportion of animal research "breakthroughs"' published in the UK national press had translated, more than 20 years later, to approved interventions?'

METHODS

We searched the Nexis media database (LexisNexis.com) for animal-based biomedical reports in the UK national press. The only restrictions were that the intervention should be specific, such as a named drug, gene, biomedical pathway, to facilitate follow-up, and that there should be claims of some clinical promise.

MAIN OUTCOME MEASURES

Were any interventions approved for human use? If so, when and by which agency? If not, why, and how far did development proceed? Were any other, directly related interventions approved? Did any of the reports overstate human relevance?

RESULTS

Overspeculation and exaggeration of human relevance was evident in all the articles examined. Of 27 unique published 'breakthroughs', only one had clearly resulted in human benefit. Twenty were classified as failures, three were inconclusive and three were partially successful.

CONCLUSIONS

The results of animal-based preclinical research studies are commonly overstated in media reports, to prematurely imply often-imminent 'breakthroughs' relevant to human medicine.

Internal fixation of osteoporotic fractures

Osteoporosis leads to bone fragility and increased risk of fracture. Despite advances in diagnosis and treatment, the prevalence continues to rise. Osteoporotic fracture treatment has a unique set of difficulties related to poor bone quality and traditional approaches, and implants may not perform well. Fixation failure and repeat surgery are poorly tolerated and highly undesirable in this patient population. This review illustrates the most recent updates in internal fixation, implant design, and surgical theory regarding treatment of patients with osteoporotic fractures.

Biomaterial scaffolds for treating osteoporotic bone

Healing fractures resulting from osteoporosis or cancer remains a significant clinical challenge. In these populations, healing is often impaired not only due to age and disease, but also by other therapeutic interventions such as radiation, steroids, and chemotherapy. Despite substantial improvements in the treatment of osteoporosis over the last few decades, osteoporotic fractures are still a major clinical challenge in the elderly population due to impaired healing. Similar fractures with impaired healing are also prevalent in cancer patients, especially those with tumor growing in bone. Treatment options for cancer patients are further complicated by the fact that bone anabolic therapies are contraindicated in patients with tumors. Therefore, many patients undergo surgery to repair the fracture, and bone grafts are often used to stabilize orthopedic implants and provide a scaffold for ingrowth of new bone. Both synthetic and naturally occurring biomaterials have been investigated as bone grafts for repair of osteoporotic fractures, including calcium phosphate bone cements, resorbable polymers, and allograft or autograft bone. In order to re-establish normal bone repair, bone grafts have been augmented with anabolic agents, such as mesenchymal stem cells or recombinant human bone morphogenetic protein-2. These developing approaches to bone grafting are anticipated to improve the clinical management of osteoporotic and cancer-induced fractures.

Fixation of distal radius fractures in adults: a review

In patients for whom function is a priority, anatomic reduction and stable fixation are prerequisites for good outcomes. Several therapeutic options exist, including orthopedic treatment and internal fixation with pins (intra- and extrafocal), external fixation which may or may not bridge the wrist, and different internal fixation techniques with dorsal or palmar plates using or not, locking screws. Arthroscopy may be necessary in case of articular fracture. In the presence of significant metaphyseal bone defects, filling of the comminution with phosphocalcic cements provides better graft stability. The level of evidence is too low to allow recommending one type of fixation for one type of fracture; and different fixation options to achieve stable reduction exist, each with its own specific complications. With the new generations of palmar plate, secondary displacement is becoming a thing of the past.

An osteoconductive, osteoinductive, and osteogenic tissue-engineered product for trauma and orthopaedic surgery: how far are we?

The management of large bone defects due to trauma, degenerative disease, congenital deformities, and tumor resection remains a complex issue for the orthopaedic reconstructive surgeons. The requirement is for an ideal bone replacement which is osteoconductive, osteoinductive, and osteogenic. Autologous bone grafts are still considered the gold standard for reconstruction of bone defects, but donor site morbidity and size limitations are major concern. The use of bioartificial bone tissues may help to overcome these problems. The reconstruction of large volume defects remains a challenge despite the success of reconstruction of small-to-moderate-sized bone defects using engineered bone tissues. The aim of this paper is to understand the principles of tissue engineering of bone and its clinical applications in reconstructive surgery.

Effect of calcium phosphate bone cement augmentation on volar plate fixation of unstable distal radial fractures in the elderly

BACKGROUND

Calcium phosphate bone cement increases the stability of implant-bone constructs in patients with an osteoporotic fracture. The purpose of this randomized study was to determine whether augmentation of volar locking plate fixation with calcium phosphate bone cement has any benefit over volar locking plate fixation alone in patients older than sixty-five years of age who have an unstable distal radial fracture.

METHODS

Forty-eight patients (fifty unstable distal radial fractures) were recruited for this study. The mean patient age was seventy-three years. Surgical procedures were randomized between volar locking plate fixation alone (Group 1) and volar locking plate fixation with injection of calcium phosphate bone cement (Group 2). The patients were assessed clinically at three and twelve months postoperatively. Clinical assessments included determinations of grip strength, wrist motion, wrist pain, modified Mayo wrist scores, and Disabilities of the Arm, Shoulder and Hand (DASH) scores. Radiographic evaluations were performed immediately postoperatively and at one year following surgery. The adequacy of the reduction was assessed by measuring radial inclination, volar angulation, and ulnar variance.

RESULTS

The two groups were comparable with regard to age, sex, fracture type, injury mechanism, and bone mineral density. No significant differences were observed between the groups with regard to the clinical outcomes at the three or twelve-month follow-up examination. No significant intergroup differences in radiographic outcomes were observed immediately after surgery or at the one-year follow-up visit. Furthermore, no complication-related differences were observed, and there were no nonunions.

CONCLUSIONS

Augmentation of metaphyseal defects with calcium phosphate bone cement after volar locking plate fixation offered no benefit over volar locking plate fixation alone in elderly patients with an unstable distal radial 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.

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.

Calcium phosphate-based composites as injectable bone substitute materials

A major weakness of current orthopedic implant materials, for instance sintered hydroxyapatite (HA), is that they exist as a hardened form, requiring the surgeon to fit the surgical site around an implant to the desired shape. This can cause an increase in bone loss, trauma to the surrounding tissue, and longer surgical time. A convenient alternative to harden bone filling materials are injectable bone substitutes (IBS). In this article, recent progress in the development and application of calcium phosphate (CP)-based composites use as IBS is reviewed. CP materials have been used widely for bone replacement because of their similarity to the mineral component of bone. The main limitation of bulk CP materials is their brittle nature and poor mechanical properties. There is significant effort to reinforce or improve the mechanical properties and injectability of calcium phosphate cement (CPC) and this review resumes different alternatives presented in this specialized literature.

Cost comparison of femoral head banking versus bone substitutes

PURPOSE

To compare the costs of femoral head banking versus bone substitutes.

METHODS

Records of femoral head banking from 1998 to 2008 were reviewed. The cost of allogenic cancellous bone graft was calculated by estimating the direct expenditure of femoral head procurement, screening tests, and storage, and then divided by the amount of bone harvested.

RESULTS

326 females and 141 males (mean age, 80.3 years) donated 470 femoral heads. Each transplantable femoral head costs US$978. Each gram of transplantable allogenic bone graft costs US$86, compared with US$9 to 26 per gram for commercially available bone substitutes.

CONCLUSION

Compared with bone substitutes, femoral head banking in Hong Kong was less economical. Unless allografts yield superior outcomes, harvesting femoral heads for general usage (such as filling bone voids for fresh fractures) is not justified from a financial perspective, especially in banks dedicated to procuring bone from femoral heads only.

Leading 20 at 20: top cited articles and authors in the Journal of Orthopaedic Trauma, 1987-2007

OBJECTIVE

To determine the 20 most cited articles and authors in the Journal of Orthopaedic Trauma during the first 20 years of publication, 1987 to 2007.

DESIGN

Review.

METHODS

We used Web of Science "cited reference search" to determine the most cited articles originating in the Journal of Orthopaedic Trauma from 1987 to 2007, the first 20 years of publication. The characteristics of each article were recorded. Next, we manually searched each author's citations for works in the same time period to determine the most cited authors. The number of first authorships for each author was then determined using Medline, and a relative citation impact ratio was calculated. Finally, citation reports for the journal overall were created to evaluate the citation impact of the journal over the last 10 years.

RESULTS

The top cited articles ranged from 64 to 566 citations with two articles over 100. Fifteen were clinical articles with the most common topic being tibia fractures (shaft, plateau, and pilon). The top cited authors ranged for 111 to 566 citations, whereas the citations per lead authorship ratio for the authors on that list ranged from 9.5 to 566 citations per lead authorship. The number of citations to the Journal of Orthopaedic Trauma overall over the last 20 years has increased from 181 in 1997 to 3050 in 2007.

CONCLUSIONS

The influence of the Journal of Orthopaedic Trauma, its articles, and its authors is readily apparent in this review of the most cited articles and authors in the journal over its first 20 years of publication. This journal is a source of highly cited original articles and the work of many highly cited leaders in the field of orthopaedic trauma.

Injectable biomaterials for regenerating complex craniofacial tissues

Engineering complex tissues requires a precisely formulated combination of cells, spatiotemporally released bioactive factors, and a specialized scaffold support system. Injectable materials, particularly those delivered in aqueous solution, are considered ideal delivery vehicles for cells and bioactive factors and can also be delivered through minimally invasive methods and fill complex 3D shapes. In this review, we examine injectable materials that form scaffolds or networks capable of both replacing tissue function early after delivery and supporting tissue regeneration over a time period of weeks to months. The use of these materials for tissue engineering within the craniofacial complex is challenging but ideal as many highly specialized and functional tissues reside within a small volume in the craniofacial structures and the need for minimally invasive interventions is desirable due to aesthetic considerations. Current biomaterials and strategies used to treat craniofacial defects are examined, followed by a review of craniofacial tissue engineering, and finally an examination of current technologies used for injectable scaffold development and drug and cell delivery using these materials.

Effect of platelet-rich plasma and latissimus dorsi muscle flap on osteogenesis and vascularization of tissue-engineered bone in dogs

PURPOSE

The present study evaluated the effects of platelet-rich plasma (PRP) and the latissimus dorsi muscle flap on osteogenesis and vascularization of tissue-engineered bone.

MATERIALS AND METHODS

Bone marrow stromal cells (BMSCs) were subcultured, and PRP was obtained from the same dogs. Demineralized bone matrix (DBM) was prepared from homologous bone. The complexes of DBM/BMSCs/PRP were implanted into areas A and B on the left side of the dogs' backs; complexes of DBM/BMSCs without PRP were implanted in areas C and D on the right side of the same dog. The implants in areas A and C were wrapped with a latissimus dorsi muscle flap, and the implants in areas B and D were wrapped with inferior fascia. At 4, 8, and 12 weeks later, the implants were removed for evaluation.

RESULTS

The radiographic evaluation, descriptive histologic analysis, and histologic quantitative analysis showed that the PRP/BMSCs/DBM complex was better than the BMSCs/DBM complex in both vascularization and osteogenesis of the ectopic tissue-engineered bones, and the complex wrapped with the latissimus dorsi muscle flap was better than that packed with superficial fascia without blood vessels.

CONCLUSIONS

The PRP and blood vessels in the latissimus dorsi muscle could cooperatively promote osteogenesis and vascularization in tissue-engineered bone.

Thoracolumbar burst fractures treated with posterior decompression and pedicle screw instrumentation supplemented with balloon-assisted vertebroplasty and calcium phosphate reconstruction

BACKGROUND

The treatment of unstable thoracolumbar burst fractures with short-segment posterior spinal instrumentation without anterior column reconstruction is associated with a high rate of screw breakage and progressive loss of reduction. The purpose of the present study was to evaluate the functional, neurologic, and radiographic results following transpedicular, balloon-assisted fracture reduction with anterior column reconstruction with use of calcium phosphate bone cement combined with short-segment posterior instrumentation and a laminectomy.

METHODS

A consecutive series of thirty-eight patients with an unstable thoracolumbar burst fracture with or without neurologic deficit were managed with transpedicular, balloon-assisted fracture reduction, calcium phosphate bone cement reconstruction, and short-segment spinal instrumentation from 2002 to 2005. Twenty-eight of the thirty-eight patients were followed for a minimum of two years. Demographic data, neurologic function, segmental kyphosis, the fracture severity score, canal compromise, the Short Form-36 score, the Oswestry Disability Index score, and treatment-related complications were evaluated prospectively.

RESULTS

All thirteen patients with incomplete neurologic deficits had improvement by at least one Frankel grade. The mean kyphotic angulation improved from 17 degrees preoperatively to 7 degrees at the time of the latest follow-up, and the loss of vertebral body height improved from a mean of 42% preoperatively to 14% at the time of the latest follow-up. Screw breakage occurred in two patients, and pseudarthrosis occurred in one patient.

CONCLUSIONS

The present study demonstrates that excellent reduction of unstable thoracolumbar burst fractures with and without associated neurologic deficits can be maintained with use of short-segment instrumentation and a transpedicular balloon-assisted reduction combined with anterior column reconstruction with calcium phosphate bone cement performed through a single posterior incision. The resultant circumferential stabilization combined with a decompressive laminectomy led to maintained or improved neurologic function in all patients with neurologic deficits, with a low rate of instrumentation failure and loss of correction.

Injectable bone cement augmentation for the treatment of distal radius fractures: a review

Fractures of the distal radius often occur as a result of low-energy trauma and are frequently seen in osteoporotic patients. Many biomechanical studies and clinical case series have been carried out to investigate the effects on the fractured bones of different fixation methods such as cast immobilization, percutaneous pins, external fixators, or open reduction with internal fixation. In addition, the use of different bone cements as stand-alone solutions or as an adjunct to the aforementioned fixation methods is described as one possible way of increasing the performance of the fixation by reducing secondary dislocation of the fragments and allowing more intensive rehabilitation of the patients. This review aims to provide an overview of some of the main issues under discussion and a critical evaluation of the different treatments.

Promontory of radius: a new anatomical description on the distal radius

Surgical treatment of distal radius fractures with palmar plates has gained popularity as the preferred approach to achieve anatomical fracture reposition. One hundred and thirty four radii of human cadavers were examined to elucidate the anatomy of the distal radius, especially the transition of the anterior into the lateral surface and a new term was given: promontory of radius. The promontory was located on the lateral surface between the changing of the convex to the concave curvature and the base of the styloid process. The anterior surface increased gradually from the ulnar notch to the lateral surface and formed the "base" of the promontory. The length of the promontory on the lateral surface measured 14-28 mm (mean 20.766 mm, SD 2.69 mm). The width of the promontory was found in between 10 and 27 mm (mean 13.857 mm, SD 2.14 mm). The width of the distal radius was 16-38 mm (mean 31.015 mm, SD 3.26 mm) and did not show any statistical correlation to the promontory. On the anterior surface the minimal width of promontory measured 4.9 mm, the maximal one 17.9 mm (mean 8.95 mm, SD 3.60). The height of the promontory on the anterior surface ranged in between 1.2 and 4.3 mm (mean 2.90 mm, SD 1.05 mm). The promontory of radius must be kept in mind to avoid any dorsal dislocation of the radial fragment often described as complication of intraarticular fractures. Based on this anatomical survey the data can be used for a new palmar radius plate designs.

Augmentation of posterior wall acetabular fracture fixation using calcium-phosphate cement: a biomechanical analysis

OBJECTIVE

This study investigates if the use of calcium phosphate cement as an adjunct to internal fixation for posterior wall acetabular fracture will result in acute restoration of joint loading parameters to the intact condition.

METHODS

Ten fresh-frozen cadaveric pelves were used for this investigation. Simulated abductor mechanism was used to load the hip. Pressure-sensitive film was used to measure contact area and pressure within the anterior, superior, and posterior regions of the acetabulum for all experimental conditions. The hips were loaded under the following 4 conditions: 1) intact; 2) following posterior wall osteotomy; 3) following reduction and standard internal fixation; and 4) following reduction of the posterior wall using calcium phosphate cement, as a grout, in addition to internal fixation. A posterior wall fracture was created along an arc of 40-90 degrees about the acetabular rim. Extensometers were utilized to measure posterior wall fragment micromotion under conditions 3 and 4 above. Statistical analysis was performed using multivariate analysis of variance to assess the significance of the difference among and between conditions simultaneously for each region. Fragment motion data were analyzed using a 2-tailed t test.

RESULTS

Fragment micromotion was reduced to 78 microm superiorly and 46 microm inferiorly with the use of calcium phosphate cement (P < 0.05). Creation of a posterior wall defect resulted in increased load in the superior acetabulum (1201N) as compared to the intact condition (902N, P = 0.024). Following reduction and internal fixation, the load distributed to the superior acetabulum (1132N) was not statistically different from the displaced condition. Following the addition of calcium phosphate cement, the load seen at the superior region of the acetabulum (883N) was less than fixation without calcium phosphate cement and was not different from the intact state (P = 0.85).

CONCLUSION

The use of calcium-phosphate cement as a fracture grout with internal fixation resulted in a partial restoration of joint loading parameters toward the intact state. Further work will be needed to determine if similar types of augmented articular fixation may result in a clinical benefit.

The use of osteoconductive bone graft substitutes in orthopaedic trauma

Several bone graft substitutes are now available for use in augmenting bone healing following trauma. Many of these products are osteoconductive and are indicated for filling bone defects in conjunction with standard methods of internal and external fixation. Osteoconduction refers to a process in which the three-dimensional structure of a substance is conducive for the ongrowth and/or ingrowth of newly formed bone. Currently used bone graft substitutes that primarily offer osteoconductive properties include coralline hydroxyapatite, collagen-based matrices, calcium phosphate, calcium sulfate, and tricalcium phosphate. These products vary considerably in chemical composition, structural strength, and resorption or remodeling rates. Understanding these differences is important in selecting a bone graft substitute with the properties desired for a specific clinical situation. The limited number of clinical studies and lack of direct-comparison studies between these products require the surgeon to fully understand the properties of each product when choosing a bone graft substitute.

Distal radius osteotomy in the elderly patient using angular stable implants and Norian bone cement

PURPOSE

To report our results after testing the combination of two technologies--angular-stable locking screw implants and Norian SRS cement--in corrective osteotomies of the distal radius in the elderly. This technique eliminates donor site bone-graft morbidity and expands the indications of corrective osteotomies to older patients with osteoporotic bone.

METHODS

Our retrospective series include 6 patients (5 women and 1 man) with an average age of 60 years. Three patients had corrections through a dorsal approach, 1 through a volar approach, and 2 through a combined approach. Two corrections included an intraarticular osteotomy. We used 2.4-mm volar T plates in patients approached volarly and 2.4-mm L and T plates for those approached dorsally; the osseous defect was filled with bone cement (Norian SRS). Range of motion and grip strength were measured at 16 months average follow-up. Standard wrist radiographs were taken to evaluate alignment and determine improvement. At final follow-up, patients completed the Modified Mayo Wrist score, the Modified Gartland and Werley score, and the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire.

RESULTS

There were no perioperative complications. All corrective osteotomies healed. One patient required a Darrach procedure at 6 months. The average wrist and forearm motion was 77% of the opposite side and grip strength 88% of the opposite side. The average total correction in the sagittal plane was 22 degrees with all patients returning to neutral or better alignment. The average ulnar variance improvement was 2 mm. Average postoperative DASH was 28 points; average Modified Mayo Wrist score was 68; and the Modified Gartland and Werley score averaged 9 points.

CONCLUSIONS

We believe that corrective osteotomy of the distal radius in the elderly using angular stable implants and Norian calcium phosphate cement is a safe and predictable surgical technique, even in patients with underlying osteoporosis. It eliminates donor site morbidity, and patient-rated outcome measures demonstrated acceptable daily living function return.

Calcium phosphate cement-assisted balloon osteoplasty for a Colles' fracture on arteriovenous fistula forearm of a maintenance hemodialysis patient

We report a case of a Colles' fracture on the arteriovenous fistula forearm of a maintenance hemodialysis patient treated with percutaneous pinning with the aid of Chinese finger trap reduction combined with cavity creation using a pediatric uromatic balloon with calcium phosphate cement augmentation. Five months after surgery, the arteriovenous fistula was patent, and the range of motion, grip strength, and radiographic findings were comparable with a non-arteriovenous fistula forearm. Wrist x-rays showed a complete union of the distal radius with progressive absorption of the calcium phosphate cement.

Vascularisation of Norian CRS bone cement and its replacement by autologous bone when used for orbital reconstruction

Various bone cements based on calcium phosphate have been used as adjuncts for repairing both the craniofacial and axial skeleton. Ideally these materials should provide initial strength and contour for the reconstruction, and be replaced over time by physiological absorption and bony deposition. Although there is evidence from animal models to support this, opportunities for human studies are rare. Here we offer clinical and histological evidence of this process.

Cement augmentation in fracture treatment

Surgical treatment of fractures close to joints, especially in osteoporotic patients, is often associated with problems to obtain adequate strength of the bone-implant construct as well as sufficient purchase for screws in the weak bone. One way to address this increasing problem is through the development of new metal implants specifically designed for fixation of fractures in osteopenic bone. An alternative strategy is to develop methods for augmentation of the weak bone that surrounds the metal implant. In most instances augmentation is achieved by using injectable cement to reinforce the bone. Conventional PMMA provides good strength but due to several drawbacks it has never gained general acceptance for fracture augmentation. More recently several injectable cements based on calcium-phosphate, calcium-sulphate or bioglass has been developed for augmentation of fractures in the extremities as well as for vertebral compressive fractures in the spine. On the basis of biomechanical studies and the clinical experience so far, cement augmentation will enable faster rehabilitation, as the strength of the cement makes it possible to allow full weight-bearing earlier than conventional metal implants alone. More clinical studies are needed in order to refine the surgical technique, develop cement types aimed for fracture treatment and define the most appropriate indications and limitations of augmentation for fracture repair. The purpose of this article is to review the possible use of augmentation as a technique in the treatment of fractures in the extremities as well as in the spine.

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.

Cancellous Allograft versus Autologous Bone Grafting For Repair of Comminuted Distal Radius Fractures: A Prospective, Randomized Trial

BACKGROUND

Distal radius fractures with a large metaphyseal defect often need defect filling. We assessed the reliability of a new allogenic transplant as a bone-graft substitute in comparison to autologous iliac crest bone-grafting.

METHODS

This prospective, randomized study included 90 patients. Fracture-osteosynthesis was done with 2.7 mm quarter-tube plates. Tutoplast-cancellous-chips were used as allografts. Clinical and radiologic parameters were determined at three and 12 months after surgery.

RESULTS

Overall outcomes were assessed according to the Demerit Point System: There were 71% good-to-excellent results in the "Tutoplast"; group and 75% good-to-excellent in the "iliac crest" group. Radiologic parameters were comparable and within normal range. Complications deriving from iliac bone harvesting were notably more frequent in the iliac crest group. Operation time was significantly shorter in the Tutoplast group.

CONCLUSION

By the use of the investigated allograft no adverse effects were detected on the outcome of the treated radius fractures. Therefore, this new allograft could be a desirable alternative to autologous bone grafting from the iliac crest, as operating and anesthetics times are shortened and complications of iliac crest bone grafting avoided.

Injectable Calcium Phosphate Bone Cement Provides Favorable Space and a Scaffold for Periodontal Regeneration in Dogs

BACKGROUND

An earlier study showed that an injectable calcium phosphate cement (CPC) served as a stable scaffold for bone formation and promoted histocompatible healing of periodontal tissue in dogs. In this study, we evaluated the influence of CPC on regeneration of periodontal defects with experimental periodontitis in dogs.

METHODS

Experimental periodontitis was induced by placing stainless-steel mesh on the mesial side of maxillary canines in six adult, healthy beagle dogs. Subsequently, intrabony defects were resized so as to be standard, and CPC was injected in the experimental bone defects. Non-grafted defects on the contralateral side served as controls. Twelve weeks after surgery, the animals were sacrificed and histologic specimens were prepared. Periodontal tissue healing was evaluated histologically and histometrically.

RESULTS

Healing of periodontal tissues, in terms of bone and cementum formation, was consistently observed in the CPC-applied sites. CPC was partly replaced by new bone. New cementum and periodontal ligament-like tissue were observed between CPC and the root surface. New bone (P <0.05), new cementum (P <0.01), and new connective tissue attachment and adhesion (P <0.05) were significantly enhanced in the experimental sites.

CONCLUSION

Calcium phosphate cement provides stable wound healing and enhanced periodontal regeneration in periodontal defects in dogs with experimental periodontitis.

Tissue engineering of bone: the reconstructive surgeon's point of view

Bone defects represent a medical and socioeconomic challenge. Different types of biomaterials are applied for reconstructive indications and receive rising interest. However, autologous bone grafts are still considered as the gold standard for reconstruction of extended bone defects. The generation of bioartificial bone tissues may help to overcome the problems related to donor site morbidity and size limitations. Tissue engineering is, according to its historic definition, an "interdisciplinary field that applies the principles of engineering and the life sciences toward the development of biological substitutes that restore, maintain, or improve tissue function". It is based on the understanding of tissue formation and regeneration and aims to rather grow new functional tissues than to build new spare parts. While reconstruction of small to moderate sized bone defects using engineered bone tissues is technically feasible, and some of the currently developed concepts may represent alternatives to autologous bone grafts for certain clinical conditions, the reconstruction of large-volume defects remains challenging. Therefore vascularization concepts gain on interest and the combination of tissue engineering approaches with flap prefabrication techniques may eventually allow application of bone-tissue substitutes grown in vivo with the advantage of minimal donor site morbidity as compared to conventional vascularized bone grafts. The scope of this review is the introduction of basic principles and different components of engineered bioartificial bone tissues with a strong focus on clinical applications in reconstructive surgery. Concepts for the induction of axial vascularization in engineered bone tissues as well as potential clinical applications are discussed in detail.

A meta-analysis of outcomes of external fixation versus plate osteosynthesis for unstable distal radius fractures

PURPOSE

External fixation and open reduction and internal fixation have been the traditional techniques for surgical fixation of unstable distal radius fractures. The existing literature has not identified which is superior, primarily because of the lack of comparative trials. We performed a comprehensive systematic review and meta-analysis of the current literature on external fixation and internal fixation of distal radius fractures to determine the dominant strategy based on available scientific evidence.

METHODS

We searched MEDLINE and EMBASE for English-language articles published between 1980 and 2004 that satisfied predetermined inclusion and exclusion criteria. The outcomes of internal and external fixation were compared using continuous measures of grip strength, wrist range of motion, and radiographic alignment and categoric measures of pain, physician-rated outcome scales, and complication rates. Outcomes were pooled by random-effects meta-analysis and meta-regression analysis was used to control for patient age, presence of intra-articular fracture, duration of follow-up period, and date of publication. Sensitivity analyses were used to test the stability of the meta-analysis results under different assumptions.

RESULTS

Forty-six articles were included in the review with 28 (917 patients) external fixation studies and 18 (603 patients) internal fixation studies. Meta-analysis did not detect clinically or statistically significant differences in pooled grip strength, wrist range of motion, radiographic alignment, pain, and physician-rated outcomes between the 2 treatment arms. There were higher rates of infection, hardware failure, and neuritis with external fixation and higher rates of tendon complications and early hardware removal with internal fixation. Considerable heterogeneity was present in all studies and adversely affected the precision of the meta-analysis.

CONCLUSIONS

The current literature offers no evidence to support the use of internal fixation over external fixation for unstable distal radius fractures. Comparative trials using appropriately sensitive and validated outcome measurements are needed to guide treatment decisions.

Bone graft substitutes: osteobiologics

Future devolvement of osteobiologic materials will no doubt replace materials currently being used. As techniques to improve biointegration and manipulation of the healing environment proceed, future graft substitutes may exceed even autogenous bone in their reliability. The primary role of bone graft use in foot and ankle surgery has been to fill traumatic defects and benign tumors or to augment arthrodesis techniques. This article highlights the osteobiologics in use today, including calcium-based ceramics, hydroxyapatite, calcium phosphates and calcium composite materials, collagen composite materials, calcium sulfate, calcium cements, and allograft.

Augmentation of intraarticular calcaneal fractures with injectable calcium phosphate cement: densitometry, histology, and functional outcome of 18 patients

Eighteen patients with intraarticular calcaneal fractures treated with open reduction and internal fixation and augmentation with an injectable carbonated apatite cement. Functional follow-up studies using the Zwipp Foot Score and densitometry were performed at 6-month intervals postoperatively. Histological samples of biopsies obtained at the time of hardware removal (6 months postoperatively) were also analyzed. The use of bone cement led to intermediate-term functional outcomes that were no better than those reported with conventional surgical procedures using bone graft. Patients demonstrated postoperative difficulties similar to those seen in other studies of this fracture, including pain, subtalar motion restrictions, peroneal impingement, and difficulties on uneven terrain and with toe- and heel-walking. However, compared to patients treated surgically without injectable carbonated apatite cement, full weight bearing on the affected extremity was regained at an average 4 weeks postoperatively. In addition, autogenous bone graft was not required to fill the osseous defect using this technique, minimizing morbidity and discomfort. During the present observation period of 3 years, only a slight decrease in the density of the peripheral zones of the cement block was observed. Histological examination revealed fibrous bone formation resulting from remodelling processes. Complete resorption and remodeling of the bone cement were not complete at 3 years. One patient developed a postoperative wound infection. Another displayed cement loosening secondary to failure of bony ingrowth.

Synthesis, material properties, and biocompatibility of a novel self-cross-linkable poly(caprolactone fumarate) as an injectable tissue engineering scaffold

A novel self-cross-linkable and biodegradable macromer, poly(caprolactone fumarate) (PCLF), has been developed for guided bone regeneration. This macromer is a copolymer of fumaryl chloride, which contains double bonds for in-situ cross-linking, and poly(epsilon-caprolactone), which has a flexible chain to facilitate self-cross-linkability. PCLF was characterized with Fourier transform infrared spectroscopy, 1H and 13C nuclear magnetic resonance spectroscopy, and gel permeation chromatography. Porous scaffolds were fabricated with sodium chloride particles as the porogen and a chemical initiation system. The PCLF scaffolds were characterized with scanning electron microscopy and micro-computed-tomography. The cytotoxicity and in vivo biocompatibility of PCLF were also assessed. Our results suggest that this novel copolymer, PCLF, is an injectable, self-cross-linkable, and biocompatible macromer that may be potentially used as a scaffold for tissue engineering applications.

Use of bone graft substitutes and bioactive materials in treatment of distal radius fractures

Although autogenous bone graft has been shown to be useful in the treatment of distal radius fractures, the role of bone graft substitutes and the optimal replacement material remains unclear. Several products are commercially available, each with differing osteoconductive, osteoinductive, and structural properties. Indications and choice of graft substitute should be based on the needs of the individual case with regard to need for structural support, gap filling, or bone healing stimulation. Further comparative research will help clarify the indications and most appropriate material for a given fracture and clinical situation.

Fibrin Gel-Immobilized Primary Osteoblasts in Calcium Phosphate Bone Cement: In vivo Evaluation with Regard to Application as Injectable Biological Bone Substitute

Osteogenic injectable bone substitutes may be useful for many applications. We developed a novel injectable bone substitute based on osteoblast-fibrin glue suspension and calcium phosphate bone cement (BC). Human osteoblasts were isolated from trabecular bone samples and cultured under standard conditions. Osteoblasts were suspended in fibrinogen solution (FS). BC was cured with thrombin solution. 8 x 4 mm injectable bone discs were prepared using silicon molds and a custom-made applicator device. Discs containing BC, BC/FS, or BC/FS/osteoblasts were implanted subcutaneously into athymic nude mice. After 3, 9 and 24 weeks, specimens were explanted and subjected to morphologic and biomechanical evaluation. In vitro fibrin gel-embedded osteoblasts displayed a differentiated phenotype as evidenced by alkaline phosphatase, collagen type 1 and von Kossa stains. A proportion of osteoblasts appeared morphologically intact over a 3-day in vitro period following application into the BC. BC/FS and BC/FS/osteoblast discs were sparsely infiltrated with vascularized connective tissue. There was no bone formation in implants from all groups. However, positive von Kossa staining only in BC/FS/osteoblast groups suggests engraftment of at least some of the transplanted cells. Biomechanical evaluation demonstrated initial stability of the composites. Young's modulus and maximal load did not differ significantly in the BC/FS and BC/FS/osteoblast groups. The practicability of osteoblast-containing injectable bone could be demonstrated. The dense microstructure and the suboptimal initial vascularization of the composites may explain the lack of bone formation. Modifications with regard to enhanced osteoblast survival are mandatory for a possible application as injectable osteogenic bone replacement system.

Palmar locking plate for treatment of unstable dorsal dislocated distal radius fractures

INTRODUCTION

This study investigates the clinical and radiological results of open reduction and internal fixation of unstable distal radial fractures using a palmar placed interlocking plate system with no substitutes for treatment of the dorsal metaphyseal fracture void.

MATERIALS AND METHODS

Nineteen patients with a mean age of 61 years (range 49-78 years) and a dorsally displaced distal radial fracture were treated using a palmar placed 2.4 mm interlocking plate system. All 17 women and 2 men were followed up according to the study protocol. Standardised radiographs in anteroposterior and lateral projection were performed before reduction and at 2, 6, 12 and 24 weeks after surgery. Radiological measurements included palmar tilt, radial inclination and radial shortening as defined by ulnar variance and intra-articular steps. Clinical assessment included active range of motion (ARM) of the wrist, pain according to a visual analogue scale (VAS), grip power, working ability, Disability of Arm, Shoulder and Hand-Score (DASH Score) and Mayo Wrist Score.

RESULTS

At final follow-up after a minimum of 11 months, the palmar tilt was +1 degrees , radial inclination 19.8 degrees and ulnar variance 1.0 mm. Mean loss of palmar tilt measured 1.9 degrees , radial inclination 1.3 degrees and ulnar variance 0.4 mm. Mean wrist extension measured 58 degrees , wrist flexion 41 degrees , pronation 83 degrees and supination 84 degrees . The Mayo Wrist Score showed 21% excellent, 58% good, 16% fair and 5% poor results.

CONCLUSION

The treatment of unstable, dorsally dislocated, distal radius fractures AO types A3, C1 and C2, with a palmar placed 2.4 mm interlocking plate system and without additional treatment of the metaphyseal defects showed good radiological and functional results with minimal loss of reduction.

SRS cancellous bone cement augmentation of calcaneal fracture fixation

BACKGROUND

The proper treatment of intraarticular calcaneal fractures remains controversial. The goal of operative treatment is to achieve anatomic reduction with stable internal fixation. One method for stabilizing fracture constructs is the use of calcium phosphate bone cement. The goal of this study was to evaluate a series of patients who had open reduction and internal fixation of intra-articular calcaneal fractures with calcium phosphate bone cement augmentation.

METHODS

Fifteen patients had open reduction and internal fixation through an extensile lateral approach with standard low-profile hardware. The walls of the bone defect beneath the posterior facet were impacted with a curette and the void filled with SRS bone cement. Preoperative and postoperative plain radiographs and computed tomography (CT) were obtained on each patient. The most recent radiographs were assessed for maintenance of reduction.

RESULTS

Nine patients were followed for an average of 13 (6 to 60) months. Six patients had less than 6 months followup. There were five type IIA, five type IIB, four type IIC, and one type IIIB-C fractures. All 15 fractures were noted on postoperative CT to have less than 2-mm of step-off with complete cement fill of the bony void. None of the patients developed a soft-tissue reaction to the cement. The first six patients were allowed to bear weight 6 weeks after injury, and the following nine patients were allowed to bear weight at 3 weeks after injury. No patient had any visible loss of reduction on most recent radiographs. Followup CT at 7 months in one patient and 12 and 51 months in another patient revealed no change in the bone-cement interface or amount of cement remaining. One patient's CT at 12 months revealed apparent fragmentation of the cement mass without loss of reduction. There was one major wound complication necessitating cement and hardware removal and free flap coverage.

CONCLUSION

In this small series, patients had no evidence of soft-tissue reaction or loss of reduction with early weightbearing after open reduction and internal fixation augmented with calcium phosphate bone cement.

Orthopaedics

Orthopaedic surgery is a large and expanding speciality. There are approximately five million clinic attendances each year in this country and musculo-skeletal complaints are the commonest presentation in General Practice. This review examines three key areas within orthopaedics, fracture management, sports medicine and the new subspeciality of minimally invasive orthopaedics and highlights areas of recent advancement, significant research and ongoing debate.

Fractures comminutives du radius distal traitées par ostéosynthèse et substitut osseux injectable

PURPOSE OF THE STUDY

Comminution is often neglected in patients presenting fractures of the distal radius. Use of injectable bone substitutes can fill the gap left by comminution, avoiding radial shortening and loss of prono-supination.

MATERIAL AND METHODS

Forty-eight patients with a distal fracture of the radius were treated by osteosynthesis and injectable cement between 1998 and 2001. These patients were reviewed at mean follow-up of 46 months (36-56). Dorsal displacement was present in all cases and the AO classification was A (n=26), B (n=15), C (n=7). Fixation was achieved with pins (n=32), posterior plate (n=14), and external fixator (n=2) before injection of the bone substitute. Outcome was evaluated with the Herzberg score, the Gartland and Werley score and DASH by an independent operator.

RESULTS

Four patients were lost to follow-up and five who developed a deformed callus after the initial osteosynthesis were excluded from the analysis. The Herzberg functional score reached 84 (range 54-100) and the Gartland and Werley radioclinical score was 4.6 (0-11) with 89% excellent and good outcomes. DASH was 23.6 (5.8-62.7). Ulnar variance was unchanged or changed less than 2 mm between the immediate postoperative period and last follow-up in 88% of patients. There was one carpal tunnel syndrome related to anterior cement leakage. Three biopsies were performed and revealed a "humid sand" aspect six months after injection as well as presence of osteoblasts within the bone substitute. There was no or very little resorption.

DISCUSSION

Several authors have demonstrated the biomechanical and functional effects of filling the comminution gap to avoid radial shortening. The first reported cases, then later prospective series, favored the use of injectable cements for patients with comminution. Cement used in our patients allowed preservation enables preservation of normal ulnar variance in addition to filling the gap. Like any bone substitute, it is an attractive alternative to other filling methods (ceramic graft) offering two advantages: adaptation to the bone defect and primary stability. This easy-to-use cement is resorbed slowly. Because of high cost, it may be reserved for patients with important functional needs.

Outcome of tibial plateau fractures managed with calcium phosphate cement

OBJECTIVES

To compare the use of an injectable calcium phosphate cement (Skeletal Repair System (SRS), Norian corporation, Cupertino, CA) and minimal internal fixation with buttress plating and bone grafting for lateral tibial plateau fractures.

STUDY DESIGN

Retrospective analysis with 13 age, sex and fracture matched pairs of tibial plateau fractures.

METHODS

Thirteen patients with lateral tibial plateau fractures treated with buttress plating and bone grafting were matched with 13 patients treated using minimal internal fixation and an injectable calcium phosphate cement (SRS). All patients were followed for a minimum of one year. The operative time, quality of reduction, maintenance of reduction and development of post-traumatic osteoarthritis was compared in both groups.

RESULTS

The mean duration of surgery was 101 min in patients treated with buttress plating and bone grafting and 55 min in patients treated with SRS (P < 0.0001). Nine patients in the internal fixation and bone graft group had excellent anatomical reductions as judged on post-operative radiographs but some loss of reduction was observed in 8 of the 13 (61%) cases. All 13 patients from the SRS group had an excellent reduction on post-operative radiographs but 3 (23%) demonstrated some loss of reduction of the plateau. The mean residual plateau depression at one year was 4mm in the buttress plate group and 0.7 mm in the SRS group (P < 0.005). Two patients (15%) in the buttress plate group developed post-traumatic osteoarthritis and required knee arthroplasty.

CONCLUSIONS

The use of SRS was associated with more favourable anatomical results than conventional treatment with buttress plating and bone grafting for lateral tibial plateau fractures.

Corrective osteotomy of malunited distal radius fractures using carbonated hydroxyapatite as an alternative to autogenous bone grafting

PURPOSE

The purpose of the present study was to report on the author's experience using carbonated hydroxyapatite as a bony substitute in distal radius corrective osteotomies.

METHODS

Six patients had a corrective osteotomy for a malunited distal radius fracture using carbonated hydroxyapatite as an alternative to an autogenous bone graft. Internal fixation of the osteotomy was achieved by using 2 or 3 K-wires.

RESULTS

At an average follow-up evaluation of 33 months (range, 22-45 mo) all the osteotomies united. Wrist flexion-extension motion improved from 75 degrees to 110 degrees , forearm rotation increased from 116 degrees to 157 degrees , and grip strength had an average increase of 140% at the time of the final follow-up evaluation. All patients were satisfied and there were no reports of persistent pain. Radiographic evaluation showed an average volar tilt improvement from a preoperative dorsal angulation shifting into a neutral position in the sagittal plane; radial lengthening improved from an average of 4 mm (range, 2-6 mm) before surgery to 7 mm (range, 5-9 mm) after surgery, ulnar plus deformity improved by 5 mm. Radiographically the carbonated hydroxyapatite material was integrated completely into the bone tissue with evidence of progressive re-absorption and bony calcification over time. The Mayo wrist score system, according to Cooney and Krimmer modifications, improved by an average of 88 and 98 points (0-100 points), respectively.

CONCLUSIONS

On the basis of this preliminary experience it is reasonable to consider carbonated hydroxyapatite as a viable alternative to bone grafting in conjunction with surgical correction of a distal radius malunion. It must be augmented, however, with internal fixation.

Intramedullary bone cementing for the treatment of Colles fracture in elderly patients

Eighteen patients with Colles fractures, mean age 70 years (range 55-91), were treated by intramedullary bone cementing. The best indication for this technique was an unstable extra-articular Colles fracture with osteoporosis. Bone cement was packed into the canal that was made by curettage of intramedullary cancellous bone from the dorsal fracture site. Intramedullary cementing caused little bleeding from the medullary canal and no irritation of the extensor tendons. Because of rigid fixation, patients could use the affected hand for light activities without any external orthosis the day after surgery. Cortical healing was seen in all cases within three months and there was no cement loosening or other complications during the mean 28 month (range 6-43) follow up period. Intramedullary bone cementing is one of the optimal treatments for Colles fractures in elderly patients.

A study of trabecular bones in ovariectomized goats with micro-computed tomography and peripheral quantitative computed tomography

Osteoporotic fractures occur most frequently in trabeculae-rich skeletal sites. The purpose of this study was to use a high-resolution micro-computed tomography (micro-CT) to investigate the changes in trabecular bone microarchitecture and to use a peripheral quantitative computed tomography (pQCT) to study changes in volumetric bone mineral density (BMD) in a large animal model resulted from ovariectomy (OVX). Ten adult goats were used for this study. The first iliac crest biopsy was harvested before OVX and served as baseline; the second biopsy was collected 6 months later from the opposite side for both pQCT and micro-CT measurements. Results showed that after 6 months of OVX, the BMD of the iliac crest biopsies decreased significantly by 16.3% (P < 0.05). The bone volume density (BV/TV), trabecular number (Tb.N), and connectivity density (Conn.D) measured with micro-CT decrease significantly after OVX, with an average decrease of 8.34%, 8.51%, and 18.52% (P < 0.05 each), respectively. The trabecular plate separation (Tb.Sp) was 8.26% (P < 0.05) greater than baseline after OVX. Significant correlations were found between the reduction of BMD and the decreases of BV/TV and Tb.N (r = 0.839 and 0.719, respectively; P< 0.001 both), as well as the increase of Tb.Sp (r = -0.758, P< 0.001) and SMI (r = -0.697, P< 0.001). In conclusion, this was the first experimental study in goat model to show that OVX-induced bone loss in goats was attributed by deterioration of trabecular microarchitecture.

Treatment of distal radius fracture with the use of calcium phosphate bone cement as a filler

A new procedure for unstable fractures of the distal radius is presented. It uses a nonbridging external fixator in conjunction with calcium phosphate bone cement through a limited exposure. The best indication for the new procedure is intra-articular fracture with some large displaced fragments in young adults. In the C2 or C3 type fractures according to AO classification, it is very difficult to obtain satisfactory fixation with a plate and screws due to comminution of the articular surface and metaphysical bone defects in many instances. After reduction of the articular surface, this new technique allows fixation of the comminuted fragments using half pins of a nonbridging external fixator. Furthermore, injection of calcium phosphate bone to the bone defect helps to make both the articular surface and the cortical bone stable. The nonbridging external fixator allows early exercises. However, it cannot be applied to all types of the fracture because of its structural limitations. The combination of nonbridging external fixation and calcium phosphate bone applications assures early exercise of the wrist.

The Use of Novabone and Norian in Cranioplasty: A Comparative Study

Bone replacement products have enhanced the ease of reconstructing bone while improving morbidity related to bone harvest. Although these products are successfully used, studies of bone healing and biomechanical strength are lacking. We aimed to compare how Norian CRS (cranial replacement substance) and Novabone C/M heal in a cranial defect. Adult New Zealand rabbits underwent removal of a critical size cranial defect. The defect was filled with Novabone (n = 8), Novabone plus demineralized bone matrix (n = 8), or Norian (n = 8), or it was left empty (n = 8). Rabbits were euthanized at 8 weeks. Cranial specimens were harvested and soft radiographs, contact microradiographs, and biomechanical testing were done. Soft radiographs revealed opacification like adjacent bone with Novabone, which was augmented when Novabone was combined with demineralized bone matrix. Norian maintained an opaque appearance. The control group did not heal. Contact microradiographs demonstrated bone within the healing defect with Novabone, which was augmented by demineralized bone matrix. Norian was not replaced with bone but served as a scaffold for bone formation. Biomechanical indentation testing demonstrated that the stiffness of Norian was the highest. Novabone plus demineralized bone matrix had a higher stiffness than Novabone alone. All experimental groups had a statistically significant difference compared with Norian. None of the groups achieved the strength of unoperated native bone. Studying two popular products, we found evidence that Novabone was incorporated into cranial bone, regenerating the bone. Novabone healed at a faster rate, creating a stronger product, with demineralized bone matrix. The biomechanical strength of the healed defect was higher in the Norian group, because the bone cement remained solid and was not incorporated, unlike crania reconstructed with Novabone.

Degradable injectable bone cement in maxillofacial surgery: indications and clinical experience in 27 patients

BACKGROUND

A carbonated apatite cement (NORIAN SRS) was used as a bone mineral substitute for the calvaria or viscerocranium in 27 patients. It has the consistency of a paste and hardens at physiologic pH and body temperature due to dahllite crystallization, which has the stoichiometric formula Ca(8.8)(HPO(4))(0.7)(PO(4))(4.5)(CO(3))(0.7)(OH)(1.3).

MATERIAL AND METHODS

The cement was used for posttraumatic bone defects in the orbital, periorbital or malar regions (nine patients), posttraumatic deformities of the frontal bone (six patients), tumour-dependent bony defects of the calvaria (two patients) and posttraumatic or cystic defects of the mandible (five patients). In another five patients, the material was used to augment the atrophic anterior mandible in combination with the insertion of dental implants. Follow-up varied between 6 and 40 months (mean: 29 months).

RESULTS

There was no inflammatory reaction surrounding the implanted material. There was no sign of infection in any of the patients and only one case of partial wound dehiscence with superficially exposed material. The defect fillings and augmentations were successful in all patients. None of the 19 dental implants which were inserted in combination with the material showed any sign of infection or loosening. Also, there was no loosening of the implants after loading (mean follow-up: 15 months). From the check-up radiographs, the material could be seen as a dense, radio-opaque structure. There were no material fractures or dislocations. Radiologically, the material seemed to be completely replaced by bony tissue after 30 months.

CONCLUSION

Our 5-year clinical experience suggests that the material is a suitable bone mineral substitute for cranio-maxillofacial surgery especially for moderate-sized defects of the calvaria and forehead bone. It has advantages over preformed, solid bone substitute materials, and, due to its initial plasticity and eventual great compressive strength, it can also stabilize dental endosseous implants in the atrophic mandible.