Use of bone-graft substitutes in distal radius fractures

Bone substitute in distal radius osteotomy: a prospective randomized double-blinded study on micromotion and outcomes in 42 patients up to one year

INTRODUCTION

Symptomatic malunion following a distal radius fracture (DRF) is commonly treated with a corrective osteotomy. Such osteotomy is traditionally fixed with a palmar plate in combination with autogenous bone graft in the osteotomy gap. However, bone grafting prolongs surgery and may result in comorbidity. Recent studies suggest that filling the osteotomy gap may not be necessary. An alternative is to fill the gap with an injectable bone substitute (IBS). However, there is limited data on inter-fragmentary micromotion in osteotomies utilizing IBS. This study aims to assess micromotion and outcomes in patients undergoing corrective osteotomy for malunited DRFs, comparing outcomes between those treated with and without IBS.

MATERIALS AND METHODS

Patients undergoing distal radius osteotomy for symptomatic malunion were randomized to either an IBS (hydroxyapatite, HA) group or control group (where the osteotomy gap was left unfilled) in combination with palmar plate fixation. Radiostereometric Analysis (RSA) markers were placed in the radius, and RSA assessments were conducted immediately postoperatively and at 6 weeks, 3, 6, and 12 months. The primary outcome of the study was dorsal/palmar tilt, while the secondary outcomes were radial shortening, radial inclination, radial shift, as well as clinical and Patient Reported Outcomes (PROMs).

RESULTS

42 patients (24 control, 18 HA-group) were included in the analysis. Significantly less micromotions were noted in the HA-group at multiple follow-ups (p ≤ 0.05) in X-axis rotation and Y-axis translation, however they were in the subclinical scale. Both groups showed functional improvements over time, but there were no differences between the groups in clinical outcomes or PROMs.

CONCLUSIONS

Hydroxyapatite bone substitute does not offer additional benefits in terms of stability or outcomes in extra-articular corrective osteotomy for malunited DRFs when a palmar plate is used for fixation and palmar cortical bone contact is maintained.

Rational design of hydrogels to enhance osteogenic potential

Bone tissue engineering (BTE) encompasses the field of biomaterials, cells, and bioactive molecules to successfully guide the growth and repair of bone tissue. Current BTE strategies rely on delivering osteogenic molecules or cells via scaffolding materials. However, growth factor- and stem cell-based treatments have several limitations, such as source restriction, low stability, difficulties in predicting long-term efficacy, and high costs, among others. These issues have promoted the development of material-based therapy with properties of accessibility, high stability, tunable efficacy, and low-cost production. Hydrogels are widely used in BTE applications because of their unique hydrophilic nature and tunable physicochemical properties to mimic the native bone environment. However, current hydrogel materials are not ideal candidates due to minimal osteogenic capability on their own. Therefore, recent studies of BTE hydrogels attempt to counterbalance these issues by modifying their biophysical properties. In this article, we review recent progress in the design of hydrogels to instruct osteogenic potential, and present strategies developed to precisely control its bone healing properties.

Heparinized chitosan stabilizes the bioactivity of BMP-2 and potentiates the osteogenic efficacy of demineralized bone matrix

Background

Demineralized bone matrix (DBM), an allograft bone processed to better expose osteoinductive factors such as bone morphogenetic proteins (BMPs), is increasingly used for clinical bone repair. However, more extensive use of DBM is limited by its unpredictable osteoinductivity and low bone formation capacity. Commercial DBM products often employ polymeric carriers to enhance handling properties but such carriers generally do not possess bioactive functions. Heparin is a highly sulfated polysaccharide and is shown to form a stable complex with growth factors to enhance their bioactivities. In this study, a new heparinized synthetic carrier for DBM is developed based on photocrosslinking of methacrylated glycol chitosan and heparin conjugation.

Results

Heparinized chitosan exerts protective effects on BMP bioactivity against physiological stressors related to bone fracture healing. It also enhances the potency of BMPs by inhibiting the activity of BMP antagonist, noggin. Moreover, heparinized chitosan is effective to deliver bone marrow stromal cells and DBM for enhanced osteogenesis by sequestering and localizing the cell-produced or DBM-released BMPs.

Conclusions

This research suggests an essential approach of developing a new hydrogel carrier to stabilize the bioactivity of BMPs and improve the clinical efficacy of current bone graft therapeutics for accelerated bone repair.

Evaluation of Antibiotic-Releasing Triphasic Bone Void Filler In-Vitro

Bone void fillers (BVFs) containing calcium sulfate, tricalcium phosphate (TCP), and hydroxyapatite can be loaded with antibiotics for infection treatment or prevention under surgeon-directed use. The aim of this study was to characterize the handling and elution properties of a triphasic BVF loaded with common antibiotics. BVF was mixed with vancomycin and/or tobramycin to form pellets, and the set time was recorded. A partial refreshment elution study was conducted with time points at 4, 8, and 24 h, as well as 2, 7, 14, 28, and 42 days. Effects on dissolution were evaluated in a 14-day dissolution study. Set time increased to over 1 h for groups containing tobramycin, although vancomycin had a minimal effect. Pellets continued to elute antibiotics throughout the 42-day elution study, suggesting efficacy for the treatment or prevention of orthopedic infections. BVF containing vancomycin or tobramycin showed similar dissolution at 14 days compared to BVF without antibiotics; however, BVF containing both antibiotics showed significantly more dissolution.

The Induction of Bone Formation: The Translation Enigma

A paradigmatic shift in the way of thinking is what bone tissue engineering science requires to decrypt the translation conundrum from animal models into human. The deductive work of Urist (1965), who discerned the principle of bone induction from the pioneering works of Senn, Huggins, Lacroix, Levander, and other bone regenerative scientists, provided the basis that has assisted future bone tissue regenerative scientists to extend the bone tissue engineering field and its potential uses for bone regenerative medicine in humans. However, major challenges remain that are preventing the formation of bone by induction clinically. Growing experimental evidence is indicating that bone inductive studies are non-translatable from animal models into a clinical environment. This is preventing bone tissue engineering from reaching the next phase in development. Countless studies are trying to discern how the formation of bone by induction functions mechanistically, so as to try and solve this enigmatic problem. However, are the correct questions being asked? Why do bone inductive animal studies not translate into humans? Why do bone induction principles not yield the same extent of bone formation as an autogenous bone graft? What are bone tissue engineering scientists missing? By critically re-assessing the past and present discoveries of the bone induction field, this review article attempts to re-discover the field of bone formation by induction, identifying some key features that may have been missed. These include a detailed library of all proteins in bones and their arrangement in the 3D superstructure of the bone together with some other important criteria not considered by tissue engineering scientists. The review therefore not only re-iterates possible avenues of research that need to be re-explored but also seeks to guide present and future scientists in how they assess their own research in light of experimental design and results. By addressing these issues bone formation by induction without autografts might finally become clinically viable.

Unexpected radiographic lucency following grafting of bone defects with calcium sulfate/tricalcium phosphate bone substitute

OBJECTIVE

To report the development of unexpected radiographic lucency (URL) corresponding to the use of a commercially available calcium sulfate/tricalcium phosphate composite used to treat benign osseous lesions.

MATERIALS AND METHODS

This is a retrospective comparative study of patients with and without URL after treatment with curettage and grafting with calcium sulfate/tricalcium phosphate. The charts of 87 patients meeting the inclusion criteria were reviewed for demographic, clinical, and radiographic data. The group with URL was compared to those with more typical patterns of graft incorporation.

RESULTS

Thirteen of 87 cases (15%) showed URL. There was no difference with respect to the pathologic subtype, anatomic location, or specific bone for the presence of URL. Of patients with URL, one (7.7%) required reoperation and regrafting, whereas among patients without URL, five (6.7%) had clinical complications, with one requiring reoperation and regrafting, and one requiring radiofrequency ablation.

CONCLUSIONS

The majority of patients treated with calcium sulfate/tricalcium phosphate cementing after curettage of low-grade bone lesions go on to uneventful healing in our series. In a minority of patients, URL occurs in lieu of the more typical pattern of centripetal incorporation. However, there is no increase in complications associated with URL. Based on these findings, patients should be informed of the possibility of this risk, although there appears to be little risk of clinically relevant adverse consequences. Physicians should be aware of this complication in order to avoid mistaking it for recurrence of the primary lesion.

Management of Severely Comminuted Distal Radius Fractures

Distal radius fractures are among the most common fractures of the upper extremity. Indications for operative and nonsurgical management have evolved over time, as have fixation techniques. Volar locking plates are commonly used in the treatment of selected distal radius fractures such as low-energy or relatively uncomplicated fractures. They have limitations, however, in the management of highly comminuted fracture patterns and in polytrauma patients. In these patients, other methods ranging from spanning fixation to fragment-specific fixation have emerged as useful alternatives in the surgeon's armamentarium for treatment of these challenging fractures.

CERAMENT treatment of fracture defects (CERTiFy): protocol for a prospective, multicenter, randomized study investigating the use of CERAMENT™ BONE VOID FILLER in tibial plateau fractures

BACKGROUND

Bone graft substitutes are widely used for reconstruction of posttraumatic bone defects. However, their clinical significance in comparison to autologous bone grafting, the gold-standard in reconstruction of larger bone defects, still remains under debate. This prospective, randomized, controlled clinical study investigates the differences in pain, quality of life, and cost of care in the treatment of tibia plateau fractures-associated bone defects using either autologous bone grafting or bioresorbable hydroxyapatite/calcium sulphate cement (CERAMENT™|BONE VOID FILLER (CBVF)).

METHODS/DESIGN

CERTiFy (CERament™ Treatment of Fracture defects) is a prospective, multicenter, controlled, randomized trial. We plan to enroll 136 patients with fresh traumatic depression fractures of the proximal tibia (types AO 41-B2 and AO 41-B3) in 13 participating centers in Germany. Patients will be randomized to receive either autologous iliac crest bone graft or CBVF after reduction and osteosynthesis of the fracture to reconstruct the subchondral bone defect and prevent the subsidence of the articular surface. The primary outcome is the SF-12 Physical Component Summary at week 26. The co-primary endpoint is the pain level 26 weeks after surgery measured by a visual analog scale. The SF-12 Mental Component Summary after 26 weeks and costs of care will serve as key secondary endpoints. The study is designed to show non-inferiority of the CBVF treatment to the autologous iliac crest bone graft with respect to the physical component of quality of life. The pain level at 26 weeks after surgery is expected to be lower in the CERAMENT bone void filler treatment group.

DISCUSSION

CERTiFy is the first randomized multicenter clinical trial designed to compare quality of life, pain, and cost of care in the use of the CBVF and the autologous iliac crest bone graft in the treatment of tibia plateau fractures. The results are expected to influence future treatment recommendations.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov: NCT01828905.

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.

Evaluation of the osteoporotic proximal humeral fracture and strategies for structural augmentation during surgical treatment

Fractures of the proximal humerus are relatively common injuries in the elderly population. Given the association between proximal humeral fractures and osteoporosis, elderly patients who sustain these injuries should always undergo a fragility fracture workup. Furthermore, a preoperative assessment of local bone quality can be critical in facilitating decision making regarding surgical and nonsurgical treatment. Modalities for quantifying osteoporosis in the proximal humerus include plain radiography and spiral computed tomography imaging. Optimal management of osteoporotic proximal humeral fractures has evolved and may now includes use of locking plates and augmentation with intramedullary fibular grafts, calcium phosphate or sulfate cement, and iliac crest bone graft. This article reviews the demographics of patients who sustain proximal humerus fractures, the appropriate postinjury fragility fracture workup, modalities for quantifying osteoporosis in the proximal humerus, techniques for augmenting fixation of proximal humerus fractures, and the authors' preferred approach to the treatment of these injuries.

Demineralized bone matrix in bone repair: history and use

Demineralized bone matrix (DBM) is an osteoconductive and osteoinductive commercial biomaterial and approved medical device used in bone defects with a long track record of clinical use in diverse forms. True to its name and as an acid-extracted organic matrix from human bone sources, DBM retains much of the proteinaceous components native to bone, with small amounts of calcium-based solids, inorganic phosphates and some trace cell debris. Many of DBM's proteinaceous components (e.g., growth factors) are known to be potent osteogenic agents. Commercially sourced as putty, paste, sheets and flexible pieces, DBM provides a degradable matrix facilitating endogenous release of these compounds to the bone wound sites where it is surgically placed to fill bone defects, inducing new bone formation and accelerating healing. Given DBM's long clinical track record and commercial accessibility in standard forms and sources, opportunities to further develop and validate DBM as a versatile bone biomaterial in orthopedic repair and regenerative medicine contexts are attractive.

Use of a proximal humeral internal locking system enhanced by injectable graft for minimally invasive treatment of osteoporotic proximal humeral fractures in elderly patients

OBJECTIVE

To investigate the effect of treatment of osteoporotic proximal humeral fractures in elderly patients with a proximal humeral internal locking system (PHILOS) and minimally invasive injectable graft (MIIG).

METHODS

Patients who conformed to the inclusion criteria were randomly divided into two groups: group A (21 cases) were treated with PHILOS alone and group B (29 cases) were treated with PHILOS augmentation plus minimally invasive injectable graft (MIIG) X3 Hivisc. Postoperative follow-up was performed regularly to check for complications, reduction loss and fracture healing by imaging. Shoulder joint function was scored and clinical results evaluated according to the Neer scoring system.

RESULTS

All patients were followed-up and achieved fracture healing. The complication rate in group A (six cases) was greater than in group B (one case), the differences being statistically significant. The reduction loss in group A (2.9 ± 0.4 mm) was greater than in group B (1.5 ± 0.3 mm), this difference also being statistically significant. According to the Neer system, the excellent and good rate was 76.2% in group A and 82.8% in group B.

CONCLUSION

PHILOS using MIPPO and augmented with MIIG X3 Hivisc produces satisfactory clinical results in aged patients with osteoporotic proximal humeral fractures and the method has advantages such as relatively minor trauma, stable fixation, fewer complications, and better joint function.

Characterization of the inflammatory response to four commercial bone graft substitutes using a murine biocompatibility model

Bone grafting is utilized in nearly all orthopedic subspecialties and in most anatomic regions. Bone graft substitutes have the potential to offer similar efficacy as autogenous grafts without the morbidity of harvest. Several studies have noted the efficacy of new-generation bone substitute products, but few studies have evaluated their safety. This study characterizes and quantifies the inflammatory reaction to four different commercially available bone graft substitutes, which were examined using the in vivo murine air pouch biocompatibility model. One coralline hydroxyapatite product was chosen as an example of a purely osteoconductive material. Three demineralized bone matrix products were chosen to represent products that are both osteoconductive and osteoinductive. Samples were implanted in a murine air pouch and harvested after 14 days in situ. Pouch fluid was extracted, mRNA isolated, and reverse transcription polymerase chain reactions carried out to detect interleukin-1 gene expression as a marker for inflammation. In addition, multiple histological characteristics were examined to quantify cellular responses to the implanted materials. All bone graft substitutes induced a significant inflammatory response compared with negative controls. Histology and polymerase chain reaction data indicated that the level of inflammatory reaction was elevated in materials with a higher demineralized bone matrix to carrier proportion. The hydroxyapatite product generated a low inflammatory reaction. In conclusion, this study used an in vivo model of biocompatibility to demonstrate that a significant inflammatory reaction occurs when using implanted bone graft substitutes. When choosing a bone grafting method, surgeons should consider both the efficacy and safety of methods and materials used. Further studies are necessary to determine the ideal bone graft material to maximize efficacy while minimizing morbidity.

The in vitro elution of BMP-7 from demineralized bone matrix

Demineralized bone matrix (DBM) grafts induce new bone formation by locally releasing matrix-associated growth factors, such as bone morphogenetic proteins (BMPs), to the surrounding tissue after implantation. However, the release kinetics of BMPs from DBM lack characterization. Such information can potentially help to improve processing techniques to maximize graft osteoinductive potential, as well as increase understanding of the osteoinductive process itself. We produced DBM with three particle size ranges from bovine cortical bone, i.e., <106, 106-300, and 300-710 μm and extracted 1.5 g of each size range in 40 ml of Sorensen's buffer at room temperature for up to 168 h. The BMP-7 concentration of the DBM and the buffer were measured at each time point using enzyme-linked immunosorbant assay. Based on measurement of the concentration of BMP-7 in the buffer, the 0-8 h elution rate was high, i.e., 3.3, 2.9, and 2.2 ng BMP-7/g DBM h, and for the 8-168 h interval was much lower, at 0.039, 0.15, and 0.11 ng BMP-7/g DBM h for the three size ranges, respectively. By 168 h, there was no indication that elution was nearing completion. Measurement of the residual BMP-7 remaining in the DBM as a function of time yielded unexpected results, i.e., after the BMP-7 content of the DBM declined for the first 4-6 h, it paradoxically increased for the remaining interval. We propose a two-compartment model to help explain these results in terms of the possible distribution of BMP-7 in bone matrix.

Fixation of comminuted distal radius fractures with a mixture of calcium phosphate and calcium sulfate cement

Distal radius fracture alignment and stabilization can be a surgical challenge in the face of severe comminution and bone loss. We describe a technique using a calcium phosphate/sulfate bone cement, as an adjunct to internal fixation. This bone cement is biocompatible, osteoconductive, and sets quickly with an isothermic reaction. The use of bone cement eliminates the need for primary autologous bone grafting and allows for easier reduction and retention of reduction at the time of surgery. Bone cement is employed for the following purposes in comminuted fractures: (1) to fill a void due to lost or crushed cancellous bone, (2) to hold larger unstable fragments while hardware is placed, and (3) to retain fragments too small to take hardware. Available bone cements, studies involving the use of bone cement for distal radius fractures, indications, and surgical technique will be reviewed.

The role of bone allografts in the treatment of angular malunions of the distal radius

PURPOSE

Two cohorts of patients who had corrective osteotomies and volar platings for malunited fractures of the distal radius were compared retrospectively to determine whether the time to union and the outcome were affected by bone allograft.

METHODS

Patients in the first group (n = 14) did not receive any bone graft; patients in the second group (n = 14) had allograft bone chips following volar plating. Indications for surgery, surgical technique, and postoperative rehabilitation were the same in both groups. Volar cortical contact was maintained using a volar locking plate in all patients. Radiographic parameters of deformity correction, time to union, wrist and forearm range of motion, grip strength, patient-rated wrist evaluation and Disabilities of the Arm, Shoulder, and Hand questionnaire were used to evaluate the outcome before and after the surgery. Average follow-up time was 36 weeks. Patients who had diabetes, who smoked, who had a body mass index of more than 35, and who required lengthening for deformity correction were excluded from the study.

RESULTS

Osteotomies in both groups healed without loss of surgical correction. Final outcome and time to union revealed no significant differences, clinically or statistically, between the 2 groups. The Disabilities of the Arm, Shoulder, and Hand score was improved in both groups.

CONCLUSIONS

When volar cortical contact was maintained using a volar locked plate, bone allograft at the osteotomy site did not improve the final outcome.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic III.

Antibacterial activity of bone allografts: comparison of a new vancomycin-tethered allograft with allograft loaded with adsorbed vancomycin

Bacterial contamination of bone allograft is a significant complication of orthopedic surgery. To address this issue, we have engineered a method for covalently modifying bone allograft tissue with the antibiotic vancomycin. The goal of this investigation was to compare the biocidal properties of this new allograft material with those of vancomycin physisorbed onto graft material. The duration of antibiotic release from the vancomycin-modified allograft matrix was determined, and no elution was observed. In contrast, the adsorbed antibiotic showed a peak elution at 24h that then decreased over several days. We next used an Staphylococcus aureus disk diffusion assay to measure the activity of the eluted vancomycin. Again we found that no active antibiotic was eluted from the covalently modified allograft. Similarly, when the vancomycin-modified allograft morsel was used in the assay, no measurable elution was observed; amounts of antibiotic released from the adsorbed samples inhibited S. aureus growth for 4-7 days. Probably the most telling property of the allograft was that after 2 weeks, the tethered allograft was able to resist bacterial colonization. Unlike the elution system in which vancomycin was depleted over the course of days-weeks, the antibiotic on the allograft was stably bound even after 300 days, while its biocidal activity remained undiminished for 60 days. This finding was in stark contrast to the antibiotic impregnated allograft, which was readily colonized by bacteria. Finally we chose to evaluate three indicators of cell function: expression of a key transcription factor, expression of selected transcripts, and assessment of cell morphology. Since the tethered antibiotic appeared to have little or no effect on any of these activities, it was concluded that the stable, tethered antibiotic prevented bacterial infection while not modifying bone cell function.

Combined xeno/auto-grafting of a benign osteolytic lesion in a dog, using a novel bovine cancellous bone biomaterial

CASE HISTORY

A 4-year-old female Labrador Retriever was diagnosed with an osteolytic lesion of the right distal radius.

CLINICAL FINDINGS

Radiographs indicated a well-circumscribed radiolucent area 18 x 15 x 8 mm, centred on the distal radial physeal scar.

DIAGNOSIS

Histopathology, performed via Jamshidi needle biopsy and following surgical curettage, was inconclusive but suggested either an aneurysmal bone cyst or fibrous dysplasia.

CLINICAL RELEVANCE

A novel processed cancellous bovine bone xenograft was used in conjunction with autogenous cancellous bone (at a ratio of approximately 4:1) to fill the curetted defect. There were no observed complications associated with the use of this new biomaterial. Osteointegration of the bone graft was followed using conventional radiographs and peripheral quantitative computed tomography (pQCT) for 10 months post-operatively. Radiographically, the osteolytic lesion modelled to resemble metaphyseal trabeculation. The cross-sectional area and the average bone density of the grafted lesion determined using pQCT data increased over time, suggesting healthy osteoconduction and native bone production.

Failure of volar locking plate fixation of an extraarticular distal radius fracture: A case report

BACKGROUND

Volar locking plates provide significant structural stability to the distal radius. Failure of a volar locked plating is a rarely reported complication in the literature.

CASE PRESENTATION

A 40 year-old, obese female patient who presented with a displaced extraarticular distal radius fracture, underwent open reduction and internal fixation of the fracture using a volar locking plate. Radiographs taken at 10 weeks postoperatively showed failure of fixation with breakage of the four distal locking screws. A hardware removal was performed at 6 months, and the patient was then lost to follow-up. She presented again at 18 months after the first surgery, with significant pain, and radiographic signs of a radial collapse and a fracture-nonunion. A total wrist fusion was performed as the method of choice at that point in time.

CONCLUSION

Volar locked plating represents the new "gold standard" of distal radius fracture fixation. However, despite the stability provided by locking plates, hardware failure may occur and lead to a cascade of complications which will ultimately require a wrist fusion, as outlined in this case report. Additional structural support by bone grafting may be needed in selected cases of volar locked plating, particularly in patients with a high risk of developing a fracture-nonunion.

Management of post-traumatic malunion of fractures of the distal radius

Distal radius malunions are a common cause of patient morbidity. This review of the literature surrounding distal radius malunion covers the demographics, pathologic anatomy, and indications for surgery, surgical techniques, and salvage options. Particular emphasis is placed on subject areas that have not been reviewed as extensively in previous articles, including: intra-articular malunion, computer-assisted techniques, bone graft alternatives, and volar fixed-angle plate osteosynthesis.

The use of calcium phosphate bone cement in fracture treatment. A meta-analysis of randomized trials

BACKGROUND

Available options to fill fracture voids include autogenous bone, allograft bone, and synthetic bone materials. The objective of this meta-analysis was to determine whether the use of calcium phosphate bone cement improves clinical and radiographic outcomes and reduces fracture complications as compared with conventional treatment (with or without autogenous bone graft) for the treatment of fractures of the appendicular skeleton in adult patients.

METHODS

Multiple databases, online registers of randomized controlled trials, and the proceedings of the meetings of major national orthopaedic associations were searched. Published and unpublished randomized controlled trials were included, and data on methodological quality, population, intervention, and outcomes were abstracted in duplicate. Data were pooled across studies, and relative risks for categorical outcomes and weighted mean differences for continuous outcomes, weighted according to study sample size, were calculated. Heterogeneity across studies was determined, and sensitivity analyses were conducted.

RESULTS

We identified eleven published and three unpublished randomized controlled trials. Of the fourteen studies, six involved distal radial fractures, two involved femoral neck fractures, two involved intertrochanteric femoral fractures, two involved tibial plateau fractures, one involved calcaneal fractures, and one involved multiple types of metaphyseal fractures. All of the studies evaluated the use of calcium phosphate cement for the treatment of metaphyseal fractures occurring primarily through trabecular, cancellous bone. Autogenous bone graft was used in the control group in three studies, and no graft material was used in the remaining studies. Patients managed with calcium phosphate had a significantly lower prevalence of loss of fracture reduction in comparison with patients managed with autograft (relative risk reduction, 68%; 95% confidence interval, 29% to 86%) and had less pain at the fracture site in comparison with controls managed with no graft (relative risk reduction, 56%; 95% confidence interval, 14% to 77%). We were unable to compare pain at the bone-graft donor site between the studies because of methodological reasons. Three studies independently demonstrated improved functional outcomes when the use of calcium phosphate was compared with the use of no grafting material.

CONCLUSIONS

The use of calcium phosphate bone cement for the treatment of fractures in adult patients is associated with a lower prevalence of pain at the fracture site in comparison with the rate in controls (patients managed with no graft material). Loss of fracture reduction is also decreased in comparison with that in patients managed with autogenous bone graft.

Management of post-traumatic malunion of fractures of the distal radius

Distal radius malunions are a common cause of patient morbidity. This review of the literature surrounding distal radius malunion covers the demographics, pathologic anatomy, and indications for surgery, surgical techniques, and salvage options. Particular emphasis is placed on subject areas that have not been reviewed as extensively in previous articles, including: intra-articular malunion, computer-assisted techniques, bone graft alternatives, and volar fixed-angle plate osteosynthesis.

Safety and efficacy of use of demineralised bone matrix in orthopaedic and trauma surgery

Demineralised bone matrix (DBM) acts as an osteoconductive, and possibly as an osteoinductive, material. It is widely used in orthopaedic, neurosurgical, plastic and dental areas. More than 500,000 bone grafting procedures with DBM are performed annually in the US. It does not offer structural support, but it is well suited for filling bone defects and cavities. The osteoinductive nature of DBM is presumably attributed to the presence of matrix-associated bone morphogenetic proteins (BMPs) and growth factors, which are made available to the host environment by the demineralisation process. Clinical results have not been uniformly favourable; however, a variable clinical response is attributed partly to nonuniform processing methods found among numerous bone banks and commercial suppliers. DBMs remain reasonably safe and effective products. The ultimate safe bone-graft substitute, one that is osteoconductive, osteoinductive, osteogenic and mechanically strong, remains elusive.

Innovations in the management of displaced proximal humerus fractures

The management of displaced proximal humerus fractures has evolved toward humeral head preservation, with treatment decisions based on careful assessment of vascular status, bone quality, fracture pattern, degree of displacement, and patient age and activity level. The AO/ASIF fracture classification is helpful in guiding treatment and in stratifying the risk for associated disruption of the humeral head blood supply. Nonsurgical treatment consists of sling immobilization. For patients requiring surgery, options include closed reduction and percutaneous fixation; transosseous suture fixation; open reduction and internal fixation, with either conventional or locking plate fixation; bone graft; and hemiarthroplasty. Proximal humerus fractures must be evaluated on an individual basis, with treatment tailored according to patient and fracture characteristics.

Augmentation of demineralized bone matrix (DBM) mineralization by a synthetic growth factor mimetic

These studies evaluated whether F2A4-K-NS, a peptide mimetic of FGF-2, could augment ectopic bone production following the subcutaneous implant of human demineralized bone matrix (DBM). DBM was formulated into a gel with and without F2A4-K-NS, and injected subcutaneously into athymic rats. After 28 days the resultant tissue was excised and fixed. The tissue was examined with soft X-rays and microcomputerized tomography (micro-CT), and by histological methods. Inclusion of F2A4-K-NS with DBM resulted in an increased mineral deposition as determined by soft X-ray and micro-CT analysis and von Kossa staining. DBM-containing tissues showed extensive mineralization compared to the carrier alone, which was poorly mineralized. The mineralization was qualitatively and quantitatively the most extensive in the samples containing F2A4-K-NS plus DBM. Additionally, the highest amount of von Kossa staining for calcium was observed in tissues from animals that had received DBM plus F2A4-K-NS. In these studies, 100 ng of peptide per 0.2 mL of injectable DBM gel generated the most optimal results. The synthetic peptide F2A4-K-NS augmented DBM-induced ectopic mineralization in athymic animals.

Bone graft substitutes in the upper extremity

The development of effective bone graft substitutes is one of the most important innovations in musculoskeletal surgery. Bone graft substitutes provide an osteoconductive scaffolding similar to those of autogenous bone. They eliminate donor site morbidity,decrease operative time and complexity and treatment costs, and improve patient satisfaction. Osteoinductive and osteogenic elements may be added to further stimulate and enhance healing and incorporation of the scaffolding substance into the adjacent bone. Bone graft substitutes have proven effective in the spine and larger long bones of the extremities. The continuing development of bone graft substitutes, evaluation of their efficacy relative to autogenous bone grafts and to each other, and their use in the hand and wrist are emerging fields.

Biomechanical testing of the fractured distal radius treated with a new bone cement--is it strong enough?

This study evaluates the in vitro ability of CAP, a bone graft substitute with osteointegration and osteoconductive properties, to restore the anatomy and strength of fractured distal radii. Ten pairs of cadaveric radii were imaged and tested to failure, simulating a fracture. The radii were reconstructed using CAP and were re-fractured and sequentially imaged. The deformities of the bones were determined through computerised evaluation of the radiographs. Radiographic analysis showed that CAP is capable of restoring the anatomy of the distal radius. The load and work required to fracture intact radii were compared to those required to fracture the reconstructed radii. The load to fracture was similar in the two situations. The work to fracture, however, was higher with reconstructed radii, suggesting that these are stronger than the original bones. Our study supports the hypothesis that CAP is capable of restoring the original anatomy and dimensions of the distal radius and re-establishing its mechanical strength.

Porous poly(DL-lactic-co-glycolic acid)/calcium phosphate cement composite for reconstruction of bone defects

Calcium phosphate (Ca-P) cements are injectable, self-setting ceramic pastes generally known for their favorable bone response. Ingrowth of bone and subsequent degradation rates can be enhanced by the inclusion of macropores. Initial porosity can be induced by CO(2) foaming during setting of the cement, whereas secondary porosity can develop after hydrolysis of incorporated poly(DL-lactic- co-glycolic acid) (PLGA) microparticles. In this study, we focused on the biological response to porous PLGA/Ca-P cement composites. Pre-set composite discs of four formulations (4 wt% or 15 wt% PLGA microparticles and low or high CO(2) induced porosity) were implanted subcutaneously and in cranial defects in rats for 12 weeks. Histological analysis of the explanted composites revealed that bone and fibrous tissue ingrowth was facilitated by addition of PLGA microparticles (number average diameter of 66 +/- 25 microm). No adverse tissue reaction was observed in any of the composites. Significant increases in composite density due to bone ingrowth in cranial implants were found in all formulations. The results suggest that the PLGA pores are suitable for bone ingrowth and may be sufficient to enable complete tissue ingrowth without initial CO(2) induced porosity. Finally, bone-like mineralization in subcutaneous implants suggests that, under appropriate conditions and architecture, porous PLGA/Ca-P cement composites can exhibit osteoinductive properties. These PLGA/Ca-P composites are a promising scaffolding material for bone regeneration and bone tissue engineering.

Allograft and alloplastic bone substitutes: a review of science and technology for the craniomaxillofacial surgeon

Bone healing is a complex and multifactorial process. As such, there are numerous steps in the process to which intervention can be directed. This has given rise to many bone graft technologies that have been used to regenerate bone, creating, perhaps, a bewildering array of options. The options that surgeons have the most familiarity with are the ones that have been available the longest (i.e., autograft and allograft). Although useful for the widest spectrum of clinical applications, limitations of these grafts has prompted the development of new materials. Demineralized bone matrix formulations and synthetic ceramic materials are now being used with greater frequency. These biomaterials have demonstrated their usefulness in facial plastic and reconstructive surgery with their ability to augment and replace portions of the craniofacial skeleton. The purpose of this article is to describe and discuss the allograft and alloplastic bone grafting technologies so that the reader can consider each in the context of the others and gain a better appreciation for how each fits into the universe of existing and emerging treatments for bone regeneration.

The use of tricorticocancellous bone graft in severely comminuted intra-articular fractures of the distal radius

PURPOSE

We report the results of a retrospective study of the use of tricorticocancellous iliac crest bone graft in 12 patients with acute AO type C3.2 or type C3.3 fractures of the distal radius who were followed up for at least 1 year.

METHODS

Twelve of 17 patients treated with the protocol were available for follow-up evaluation. All fractures were treated with open reduction and combined internal and external fixation. Five fractures were plated dorsally, 1 volarly, and 5 volarly and dorsally.

RESULTS

Five patients had AO type C3.2 fractures and 7 had AO type C3.3 fractures. Nine of 10 radiographic parameters that were restored to near-normal values during the surgery were maintained at near-normal levels at the final follow-up evaluation at a mean of 28 months after surgery. Nine fractures had less than 2 mm of articular step-off of the distal radius and 8 had less than 3 mm of total articular incongruity (gap plus step-off). In 10 patients the radial length was restored to at least 10 mm. The mean arc of flexion-extension was 67% and the mean grip strength was 57% of that of the uninjured side. According to the Gartland and Werley demerit-point system 5 of the patients had good or excellent results. According to the modified Green and O'Brien clinical rating system 2 patients had good or excellent results. Poor results for 2 patients according to the demerit-point system and for 6 patients according to the Green and O'Brien clinical rating system were associated with severe ipsilateral soft-tissue and osseous injuries of the wrist, forearm, and arm. The total articular incongruity had a moderately strong correlation with the outcome as assessed by the demerit-point system.

CONCLUSIONS

Tricorticocancellous bone grafting in conjunction with combined internal and external fixation is a satisfactory treatment that can lead to a high rate of return to work and sports, a high level of patient satisfaction, and a low rate of complications.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic, Level IV.

Controlled release of rhBMP-2 loaded poly(dl-lactic-co-glycolic acid)/calcium phosphate cement composites in vivo

The release kinetics of recombinant human bone morphogenetic protein-2 (rhBMP-2) loaded poly(dl-lactic-co-glycolic acid)/calcium phosphate cement (PLGA/Ca-P cement) composites were studied in vivo. RhBMP-2 was radiolabeled with (131)I and entrapped within PLGA microparticles or adsorbed onto the microparticle surface. PLGA microparticles were prepared of high molecular weight (HMW) PLGA (weight average molecular weight [M(w)] 49,100+/-1700) or low molecular weight (LMW) PLGA (M(w) 5,900+/-300) and used for preparation of 30:70 wt.% PLGA/Ca-P cement composite discs. Release of 131I-rhBMP-2 loaded composites was assessed by scintigraphic imaging according to a 2(2) two-level full factorial design in the rat ectopic model during four weeks. In vivo release kinetics varied among formulations. All formulations showed slow release without initial burst, and displayed a linear release from 3 to 28 days. Release of LMW entrapped rhBMP-2 composites (1.7+/-0.3%/day) was significantly faster than release from other formulations (p<0.01). After 28 days, retention within the composites was 65+/-5%, 75+/-4%, 50+/-4% and 70+/-6% of the initial rhBMP-2 for HMW entrapped, HMW adsorbed, LMW entrapped and LMW adsorbed rhBMP-2 composites, respectively. Release from the composite was probably slowed down by an interaction of rhBMP-2 and Ca-P cement after rhBMP-2 release from PLGA microparticles. We conclude that PLGA/Ca-P cement composites can be considered as sustained slow release vehicles and that the release and retention of rhBMP-2 can be modified according to the desired profile to a limited extent.

The Hydration Characteristics of Demineralized and Nondemineralized Allograft Bone: Scientific Perspectives on Graft Function

Demineralized bone matrix grafts are osteoinductive due to the increase in bioavailability of bone morphogenetic proteins that occurs from demineralization. The manner by which demineralization increases their bioavailability, however, is not known with certainty. It is known that the mineral phase of bone masks the proteins of the organic matrix. Proteins depend on their interaction with water for their three-dimensional conformation, biologic activity, and stability. It is possible that demineralization allows a more complete hydration of bone matrix, changing the local environment and allowing the bone morphogenetic proteins to desorb and form a concentration gradient, signaling the appropriate cell types to begin the process of bone regeneration. Under similar test conditions, it was discovered that hydration of demineralized bone matrix powder produces a strong exotherm on the order of 14 degrees C whereas hydration of bone powder produces a smaller exotherm of about 2 degrees C. The details of the hydration reactions of demineralized bone matrix and bone were investigated by measuring the exotherm produced under varying conditions. The results suggest that bone mineral does mask, or limit, the ability of the organic matrix to interact with water. An understanding of the hydration characteristics of demineralized bone matrix can also help in the development of carrier systems that optimize osteoinductive potential.

Assay of Bone Morphogenetic Protein-2, -4, and -7 in Human Demineralized Bone Matrix

Demineralized bone matrix (DBM) is a widely used bone graft material that derives its osteoinductive potential from matrix-associated bone morphogenetic proteins (BMPs). Prior investigations have shown that the osteoinductive potential can vary widely, with influence from both donor and processing sources. Although it is plausible that donor variance in the BMP profile can be an important consideration, the few published studies available have given inconsistent and incomplete information about this. The goal was to (1) characterize the variance of BMP-2, BMP-4, and BMP-7 in fully demineralized DBM derived from 20 appropriately screened (Food and Drug Administration and the American Association of Tissue Banks criteria) donors (male and female, 17-65 years) and (2) using literature review, infer the potential for this to be an important source of variability in graft function. BMPs were extracted with 4 M guanidine hydrochloride, and levels of BMP-2, BMP-4, and BMP-7 were measured using enzyme-linked immunosorbent assay. Measured levels were as follows: BMP-2 = 21.4 +/- 12.0 ng/g DBM, BMP-4 = 5.45 +/- 2.04 ng/g DBM, and BMP-7 = 84.1 +/- 34.4 ng/g DBM, which were significantly different (P < 0.05). There was a positive linear correlation between BMP-2 and BMP-7 (P = 0.0227). DBM derived from female donors had significantly greater concentrations of BMP-2 and BMP-7 than did that derived from male donors (P = 0.0257 and 0.0245, respectively). There was no significant correlation between donor age and the levels of any of the measured BMPs. The magnitude of variance of BMP profile appears to reasonably well correspond to the variance in osteoinductive potential cited by others, suggesting the possibility of using this as a method of donor screening.

Coralline hydroxyapatite bone graft substitute in hindfoot surgery

BACKGROUND

Coralline hydroxyapatite bone graft substitute material is created by the conversion of the calcium carbonate structure of coral into hydroxyapatite. The microstructure of the material resembles cancellous bone and provides an osteoconductive scaffold for bone ingrowth. The use of this material is reported in the orthopedic oncology and trauma literature. Short-term reports in foot procedures have been reported.

METHOD

A retrospective review identified 10 patients who had undergone hindfoot arthrodesis with coralline hydroxyapatite bone graft. The charts were reviewed for outcomes, operative complications, and time to union. Nine of the 10 patients were available for additional examination.

RESULTS

The average followup was 6 years. There were three complications. One patient had sural nerve numbness with partial resolution which was unrelated to the graft material. A rheumatoid patient on methotrexate and prednisone developed a deep wound infection 9 months after surgery. One patient had a nonunion of the talonavicular joint. Eight of the 10 patients reported good or excellent results. Radiographs continued to demonstrate the presence of the graft material at 6 years. Radiographs showed extrusion of the graft from the joint in all patients. No patient had symptoms from the extruded material.

DISCUSSION

Coralline hydroxyapatite bone graft substitute appears to be a clinically effective material for use in foot procedures. No adverse events could be linked to the graft material. The graft material is difficult to contain and extrusion was present in all patients. The slow resorption is a concerning characteristic of the graft material. At 6-year followup, the continued presence of the material has not shown any adverse effect.

Calcium phosphate cement in musculoskeletal tumor surgery

BACKGROUND AND OBJECTIVES

Calcium phosphate cement (CPC) is an injectable biocompatible bone substitute that has been used for various applications in orthopedic surgery. However, no extensive clinical studies of the use of CPC to fill bone cavities after curettage of musculoskeletal tumors have been reported. The present study reviewed the results for 56 musculoskeletal tumors treated by curettage and CPC implantation.

METHODS

Assessment was based on clinical examination and radiographic findings. Variables for clinical assessment included pain, limb function, and complications. Median follow-up was 18.5 months (range 6-47 months).

RESULTS

One patient experienced post-operative fractures. Three patients displayed local recurrence. One patient developed post-operative superficial wound infection, and two patients with large bony defect exhibited non-infectious serous discharge. No serious adverse effects such as deep venous thrombosis, pulmonary embolism were encountered. In all cases, CPC was radiographically well adapted to the surrounding host bone as of final follow-up.

CONCLUSIONS

CPC appears to offer a useful bone substitute for the treatment of musculoskeletal tumors. As the follow-up period for this study was short, further long-term follow-up studies are needed.

Biocompatibility and degradation of poly(DL-lactic-co-glycolic acid)/calcium phosphate cement composites

Injectable calcium phosphate (Ca-P) cement materials exhibit favorable osteocompatible behavior but are resorbed slowly because of a lack of a bone ingrowth-enabling macroporosity. In this study, poly(DL-lactic-co-glycolic acid) (PLGA) microparticles (average size 66 +/- 25 microm) were incorporated into Ca-P cement to obtain a macroporous Ca-P cement scaffold after PLGA hydrolysis in vivo. Preset PLGA/Ca-P cement composite discs of various weight ratios (0/100, 15/85, 30/70, and 50/50) were implanted subcutaneously and in cranial defects in rats for 12 weeks. Histological analysis revealed that all macropores in the PLGA-containing composites (average pore size 73 +/- 27 microm) were filled with fibrous tissue and blood vessels (subcutaneous implants) and/or bone (cranial implants). Histologically, bone formation appeared most abundant and most consistent in the 30/70 PLGA/Ca-P cement composites. Histomorphometrical evaluation revealed a significant increase in defect fill in the 15/85 and 30/70 PLGA/Ca-P cement composites. Finally, subcutaneous and cranial 50/50 PLGA/Ca-P cement composites had degraded to a large extent, without adequate replacement by bone in the cranial implants. Therefore, we conclude that PLGA/Ca-P cement composites enable tissue ingrowth and show excellent osteocompatibility in weight ratios of 15/85 and 30/70 PLGA/Ca-P cement. In this model, 30/70 PLGA/Ca-P cement composites showed the most favorable biological response.

Demineralized bone matrix graft: a scientific and clinical case study assessment

Osteoinductive demineralized bone matrix results from bone demineralization and is attributed to matrix-associated bone morphogenetic proteins. The osteoinductive potential can vary with donor. Many bioassay methods are available to screen donors, each with its own interpretation, so performance of more than one may be of value. Furthermore, little is known about the relationship between bioassay results and clinical outcomes. A study designed to meaningfully explore these issues would require assay of a large number of donors as well as clinical utilization in a large patient population. A preliminary study was undertaken to gain initial perspective. Using demineralized bone matrix derived from one 33-year-old female donor, 2 methods of bioassay and a clinical case study were performed. The levels of bone morphogenetic proteins 2, 4, and 7 in lyophilized demineralized bone matrix powder were measured (19.65 +/- 0.30 ng/g, 2.49 +/- 0.19 ng/g, and 82.03 +/- 6.89 ng/g, respectively). Also, putty (Osteostim DBM Putty), prepared from powder, was intramuscularly implanted in athymic rats and de novo bone formation quantified (6.7% +/- 3.5% new bone formation with 49% +/- 17% of the implant area associated with new bone formation). The putty, in conjunction with internal fixation, was used in the revision of a medial malleolar nonunion of an obese, 76-year-old woman. Radiographic union with excellent graft incorporation was achieved by 12 weeks postoperatively, with maintenance of an acceptable clinical result during the 14-month follow-up period. These results are interpreted in the broader context of demineralized bone grafting, in general, and an outline for further study is presented.

Combined internal and external fixation of distal radius fractures

Combined internal and external fixation of distal radius fractures is used most commonly to treat injuries with joint surface or metaphyseal comminution. External fixation aids reduction intraoperatively and facilitates arthroscopic, per-cutaneous, or open manipulation of the fracture. Internal fixation maintains precise reduction of critical anatomy, principally the contour and orientation of the articular surface. Postoperatively the fixator functions as a neutralization device, preventing fracture collapse and decreasing the biomechanical demands on the internal fixation hardware. The combined technique exploits the benefits of both forms of fixation, allowing each to be used to full advantage in the treatment of complex distal radius fractures.

The evaluation of processed cancellous bovine bone as a bone graft substitute

OBJECTIVE

To determine the ability of a novel bovine cancellous bone xenoimplant to act as an osteoconductive graft in an ovine femoral defect model. An autograft harvested from the xenoimplant site was placed in a contralateral limb defect for comparison.

MATERIAL AND METHODS

The xenoimplant used had been rendered immunologically inert by a novel defatting and deproteinating process. Following surgical implantation of cores into condylar cancellous bone defects, fluorochrome labels were administered to 12 sheep at 2 1/2, 4 1/2 and 8 weeks. Incorporation of the xenoimplants and autografts into the host bone was compared radiographically and histomorphometrically at 10 weeks.

RESULTS

Radiographically, the degree of osteointegration was comparable. Histomorphometric data, consisting of labelled surface (LS) estimates, confirmed osteoconductive properties of both the xenoimplants and autografts. Remodelling activity was greatest in the xenoimplants at 2 1/2, weeks. At 4 1/2 weeks, there was more activity in the autograft, but by 8 weeks they were performing similarly. Xenoimplant-LS estimates were comparable or greater than those of the autograft at all times.

CONCLUSIONS

Processed bovine cancellous bone xenoimplants were osteoconductive in this model and show promise for development as a biomaterial in human and veterinary orthopaedic surgery.

Osteogenic Differentiation of Human Bone Marrow Stromal Cells on Partially Demineralized Bone Scaffoldsin Vitro

Tissue engineering has been used to enhance the utility of biomaterials for clinical bone repair by the incorporation of an osteogenic cell source into a scaffold followed by the in vitro promotion of osteogenic differentiation before host implantation. In this study, three-dimensional, partially demineralized bone scaffolds were investigated for their ability to support osteogenic differentiation of human bone marrow stromal cells (BMSCs) in vitro. Dynamic cell seeding resulted in homogeneous cell attachment and infiltration within the matrix and produced significantly higher seeding efficiencies when compared with a conventional static seeding method. Dynamically seeded scaffolds were cultured for 7 and 14 days in the presence of dexamethasone and evaluated on biochemical, molecular, and morphological levels for osteogenic differentiation. Significant elevation in alkaline phosphatase activity was observed versus controls over the 14-day culture, with a transient peak indicative of early mineralization on day 7. On the basis of RT-PCR, dexamethasone-treated samples showed elevations in alkaline phosphatase and osteocalcin expression levels at 7 and 14 days over nontreated controls, while bone sialoprotein was produced only in the presence of dexamethasone at 14 days. Scanning electron microscopy evaluation of dexamethasone-treated samples at 14 days revealed primarily cuboidal cells indicative of mature osteoblasts, in contrast to nontreated controls displaying a majority of cells with a fibroblastic cell morphology. These results demonstrate that partially demineralized bone can be successfully used with human BMSCs to support osteogenic differentiation in vitro. This osseous biomaterial may offer new potential benefits as a tool for clinical bone replacement.

Fracture Fixation

The basic goal of fracture fixation is to stabilize the fractured bone, to enable fast healing of the injured bone, and to return early mobility and full function of the injured extremity. Fractures can be treated conservatively or with external and internal fixation. Conservative fracture treatment consists of closed reduction to restore the bone alignment. Subsequent stabilization is then achieved with traction or external splinting by slings, splints, or casts. Braces are used to limit range of motion of a joint. External fixators provide fracture fixation based on the principle of splinting. There are three basic types of external fixators: standard uniplanar fixator, ring fixator, and hybrid fixator. The numerous devices used for internal fixation are roughly divided into a few major categories: wires, pins and screws, plates, and intramedullary nails or rods. Staples and clamps are also used occasionally for osteotomy or fracture fixation. Autogenous bone grafts, allografts, and bone graft substitutes are frequently used for the treatment of bone defects of various causes. For infected fractures as well as for treatment of bone infections, antibiotic beads are frequently used.

Calcium sulfate used as bone graft substitute in acetabular fracture fixation

The purpose of this study was to determine the natural history of calcium sulfate pellets implanted during acetabular fracture surgery. The study group consisted of patients sustaining an acetabular fracture with intraarticular comminution or marginal impaction or both in whom calcium sulfate pellets were implanted in lieu of autologous bone graft. Between 1997 and 1999, 32 fractures were treated. Followup adequate to delineate pellet outcome, including radiographs and computed tomography, was obtained in 31 patients. Evaluation of plain radiographs showed that the calcium sulfate pellets became undifferentiated from the surrounding bone at an average of 7 weeks postoperatively. In no case was a residual bony deficit seen. Computed tomography analysis showed that in 22 patients, the pellets essentially had been (> 90%) replaced by bone and in four patients, the majority (> 50%-90%) of the pellets had been replaced by bone. However, in five patients, less than 50% of the pellets had been replaced by bone, including one showing no bony replacement. The common finding in patients with an extensive residual deficit was direct communication of the pellets with the joint space shown on the postoperative computed tomography scan. Patients with the best results had complete containment of the pellets within bone. Therefore, it seems that implanted calcium sulfate pellets in contact with joint synovial fluid are at risk for resorption without significant bony response. If calcium sulfate pellets are to be implanted in a periarticular location, complete bony containment is desirable. Evaluation of the periacetabular bony response requires computed tomography scans, as plain radiographs are inadequate for this purpose.

Bone graft substitutes

A better understanding of the biology of fracture healing and an increasing awareness of the limitations and potential complications of autogenous bone graft harvest have combined to foster a burgeoning interest in the development of bone graft substitutes. A few of these materials have been available for more than a decade, and many more should become available in the near future. The characteristics of the ideal bone graft substitute may vary considerably depending on the intended site of application and the clinical setting in which it is used. Knowledge of the available alternatives is a necessary prerequisite to informed decision making.

The use of BoneSource hydroxyapatite cement for traumatic metaphyseal bone void filling

OBJECTIVE

This prospective, randomized study was performed to determine whether a new, in situ setting hydroxyapatite cement is as safe or effective as autologous cancellous bone graft for the treatment of metaphyseal bone voids secondary to trauma. This was a multicenter study including Level I trauma centers and university hospitals. Thirty-eight patients who sustained an acute closed or open type I fracture of the humerus, radius, ulna, femur, tibia, or calcaneus and had a traumatic bone void requiring grafting of the metaphyseal or cancellous bone area were enrolled. Open reduction and internal fixation of the fracture was performed with use of either autologous cancellous bone or BoneSource hydroxyapatite cement to fill traumatic metaphyseal voids. Main outcome measures included maintenance of reduction, fracture healing, pain at defect site, pain at donor site, and clinical function of the limb.

RESULTS

Patients treated with BoneSource had an 83% success rate in maintaining reduction, whereas patients treated with autograft had a 67% success rate. A successful clinical outcome, as measured by a healed fracture with minimal to no pain, moderate to maximum function, and no or minor donor site complications, was seen in 69% of patients treated with BoneSource and 57% of patients treated with autograft. In patients with at least 1 year of follow-up, the overall success rate was 79% in the BoneSource group and 70% in the autograft group.

CONCLUSION

BoneSource is safe and effective when used to fill traumatic metaphyseal bone voids. It is at least as good as autograft for treatment of these defects.

A biomechanical comparison of fragment-specific fixation and augmented external fixation for intra-articular distal radius fractures

The biomechanical stability of an internal fixation system that uses low-profile modular implants to stabilize individual fracture components was studied in a validated cadaver fracture model that incorporated physiologic muscle forces and wrist motion. Fragment-specific fixation with immediate range of motion was compared with static augmented external fixation in simulated, unstable 3- and 4-part intra-articular distal radius fractures (n = 20). Fixation was applied and specimens were loaded via their major wrist tendons. Because the wrist joint was not constrained in the internal fixation group, full wrist motion occurred during load application in these specimens. A 3-dimensional motion tracking system calculated individual fracture fragment motion in both groups. In the 3-part fracture pattern fragment-specific fixation showed comparable stability to static augmented external fixation despite the full wrist range of motion that occurred during application of load in these specimens. In the 4-part fracture pattern fragment-specific fixation was shown to be significantly more stable when compared with static augmented external fixation in 4 of 6 axes of motion. Our findings confirm the stability of this low-profile plating system and support the consideration of early wrist motion when treating complex, intra-articular distal radius fractures with fragment-specific fixation.