Norian SRS versus external fixation in redisplaced distal radial fractures. A randomized study in 40 patients

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.

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

In the treatment of displaced tibial plateau fractures, filling the resultant metaphyseal defect is essential for maintaining reduction. This study reports on 14 patients with an average age of 53 (range 34-63) years who sustained such a fracture and whose tibial defect was augmented with an injectable calcium phosphate cement under arthroscopic and fluoroscopic control. Eight fractures were treated with subcortical percutaneous screw fixation, plates were used in four cases and two fractures were treated with bone cement only. Full weight-bearing was allowed after 6-12 weeks. At the last follow-up which averaged 28 (range 18-47) months, the reduction achieved at the index operation was not altered in any of the patients except one. Most patients recorded little or no pain with an average VAS score of 1.2 (0-3.4). Ten patients had no limitation of their walking distance. Patient satisfaction was good or excellent in 12 cases. Flexion averaged 140 degrees (range 130-150 degrees ) and extension was unlimited in 13 patients. The Lysholm knee score averaged 80 and the Knee Society score 180 (range 127-195). In our opinion the injectable calcium phosphate cement used here is a promising alternative for filling metaphyseal defects in the treatment of displaced tibial plateau fractures.

Surgical interventions for treating distal radial fractures in adults

BACKGROUND

Fracture of the distal radius is a common clinical problem, particularly in older white women with osteoporosis.

OBJECTIVES

To determine when, and if so what type of, surgical intervention is the most appropriate treatment for fractures of the distal radius in adults.

SEARCH STRATEGY

We searched the Cochrane Musculoskeletal Injuries Group specialised register (November 2002), the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 1, 2003), MEDLINE (1966 to February 2003), EMBASE (1988 to 2003 Week 8), CINAHL (1982 to February 2003), the National Research Register (Issue 1, 2003), PEDro, conference proceedings and reference lists of articles. No language restrictions were applied.

SELECTION CRITERIA

Randomised or quasi-randomised clinical trials involving skeletally mature patients with a fracture of the distal radius, which compared surgical treatment with conservative treatment, different types of surgical intervention or the duration of immobilisation after surgery. The main categories of surgical intervention were external fixation, percutaneous pinning, open reduction and internal fixation, and the insertion of bone scaffolding materials.

DATA COLLECTION AND ANALYSIS

All trials, meeting the selection criteria, were independently assessed by both reviewers for methodological quality. Data were extracted for anatomical, functional and clinical outcomes (including complications). The trials were grouped into categories relating to the main comparisons and types of surgical intervention. Despite clear heterogeneity in the characteristics of comparable trials, pooling of data was undertaken where possible and appropriate.

MAIN RESULTS

Forty eight trials, examining 25 treatment comparisons, met the inclusion criteria of this review. These involved a total of 4371 mainly female and older patients with generally displaced, often comminuted and potentially or evidently unstable fractures. Nearly half of the trials compared surgery with plaster cast immobilisation. Summarising the outcomes was hampered by the variation between the studies in participant characteristics, interventions, quality of trial methodology and reporting, and outcome measurement. Surgical methods were usually associated with better anatomical appearance after fracture healing, but there was inadequate evidence to confirm that these had resulted in better functional and clinical outcomes for the patients.

REVIEWER'S CONCLUSIONS

The 48 randomised trials do not provide robust evidence for most of the decisions necessary in the management of these fractures. Although, in particular, there is some evidence to support the use of external fixation or percutaneous pinning, their precise role and methods are not established. It is also unclear whether surgical intervention of most fracture types will produce consistently better long-term outcomes. There is a need for good quality evidence for the surgical management of these fractures.

Condylar Stabilizing Technique with AO/ASIF Distal Radius Plate for Colles' Fracture Associated with Osteoporosis

The author established a new reduction and fixation technique for osteoporotic distal radius fracture with a use of AO/ASIF volar distal radius plate, referring to the condylar plating technique in distal femoral fracture. This technique is performed in three steps. First, distal fixation is through the insertion of buttress pins just beneath the subchondral bone with a convergent angle of 10 degrees to the articular surface under fluoroscopic assistance. Second, the proximal limb of the plate is lined up with the radius shaft so that the fracture is reduced automatically and anatomically. Third, by rotating the proximal limb of the plate ulnarly and lifting up the ulnar border of the articular surface, the fracture is fixed less than the contralateral ulnar variance, to apply an adequate tension on the triangular fibrocartilage complex (TFCC). This method represents a valuable treatment modality for the most frequent types of unstable distal radius in elderly women.

Norian SRS versus functional treatment in redisplaced distal radial fractures: a randomized study in 20 patients

We compared the use of Norian SRS, an injectable calcium phosphate bone cement, with functional treatment of redisplaced distal radial fractures in a prospective randomized study of 20 patients. The redisplaced fractures were either rereduced and stabilized by Norian SRS, or the displaced position was accepted and was not rereduced. All wrists were immobilized in a short-arm dorsal splint for 1 week, followed by a removable splint for another 3 weeks. The chosen primary effect variable was grip strength at 7 weeks, and this did not differ between the two treatment groups. The clinical results at 6 months in both groups were similar. We conclude that aggressive treatment of redisplaced fractures of the distal radius may be unnecessary in most women aged 50 years or more.

Applications of calcium phosphate-based cancellous bone void fillers in trauma surgery

For more than a century, fracture repair has been augmented with autogenous cancellous bone grafting, which supplies 3 requisite properties: growth factors for osteoinduction, progenitor stem cells for osteogenesis, and scaffolding for osteoconduction. However, disadvantages to using autogenous bone include procurement morbidity, longer operative time, and limited availability. Allograft is more readily available but does not supply osteoinductive or osteogenic properties. Better alternatives for bone grafting currently include autologous bone marrow, ceramics, allograft demineralized bone matrix, and regulatory growth factors; however, none of these fulfills all 3 requisite properties. Replacement or augmentation of autograft with a calcium phosphate-based composite graft, which combines the best elements of each component into a single engineered graft, is discussed.

Limitations of autograft and allograft: new synthetic solutions

Autogenous cancellous bone is widely regarded as an ideal construct for graft procedures, supplying osteoinductive growth factors, osteogenic cells, and a structural scaffold. However, procurement morbidity and constraints on obtainable quantities limit its use. Allograft is the next best alternative at present; however, minor immunogenic rejection and risk of disease transmission are unresolved issues. Although synthetic grafting materials eliminate these risks, these materials do not transfer osteoinductive or osteogenic elements to the host site. To offer the advantages of autograft and allograft, a composite graft may be considered. Such a graft can combine a synthetic scaffold with biologic elements to stimulate cell infiltration and new bone formation.

The role of the osteoconductive scaffold in synthetic bone graft

Autogenous bone is regarded as the gold standard for bone graft materials as it provides 3 elements necessary to generate and maintain bone: scaffolding for osteoconduction, growth factors for osteoinduction, and progenitor cells for osteogenesis. Allograft is more limited than autograft in these essential elements and yields more variable clinical results. Composite synthetic grafts offer an alternative that can potentially unite the 3 salient bone-forming properties in more controlled and effective combinations than can be obtained in many clinical situations, without the disadvantages found with autograft. This article examines the underemphasized but crucial role of the osteoconductive scaffold in the composite synthetic bone graft.

Controlled trial of distal radial fractures treated with a resorbable bone mineral substitute

This randomized trial compared the use of hydroxyapatite cement with Kapandji wiring in distal radial fractures. Two groups of nine patients with distal radial fractures were either treated by reduction and fixation with wires or insertion of the cement into the fracture void. There was no difference between the groups before operation, on reduction or at day 1. Dorsal angle in the hydroxyapatite group was significantly worse at 6, 12 and 26 weeks. Grip strength and palmar flexion were poor in the hydroxyapatite cement group. All the clinical parameters and X-ray variables were worse at 12 and 26 weeks in the hydroxyapatite cement group. We conclude from this trial that there is nothing to support the use of this hydroxyapatite cement, without the use of additional fixation, in distal radial fractures.

Use of an injectable calcium phosphate bone cement in the treatment of tibial plateau fractures: a prospective study of twenty-six cases with twenty-month mean follow-up

OBJECTIVE

To evaluate the potential benefit of a new injectable mineral bone cement (Norian SRS, Cupertino, CA, USA) for the treatment of tibial plateau fractures OTA types 41.B2-B3 and C3.

DESIGN

Prospective study with established protocol.

SETTING

University hospital; university teaching hospital.

PATIENTS

Twenty-six patients gave informed consent to participate in this study and were available for follow-up examinations. All patients had sustained intraarticular tibial plateau fracture types OTA B2-B3 and C3. All cases were followed with a mean follow-up time of 19.7 months (6 to 36 months, median eighteen months).

INTERVENTION

Twenty-five cases were treated with open reduction, osteosynthesis with screws or plate, and injection of Norian SRS in the subchondral bone defect. One case had closed reduction, screw osteosynthesis, and percutaneous cement injection.

MAIN OUTCOME MEASUREMENTS

Radiographs in two planes were evaluated prospectively at six, twelve, and twenty-six weeks postoperatively and at last follow-up using Rasmussen's radiologic score. Clinical parameters were measured at the same time intervals using Lysholm's and Tegner's knee scores.

RESULTS

Two cases required early wound revisions because of sterile drainage. Two cases developed partial loss of reduction of the fracture between four and eight weeks after surgery, requiring revision surgery in one case (total complication rate 15.3 percent). No other patients had complications, and all other fractures healed without any displacement. The high mechanical strength of the cement allowed early weight bearing after a mean postoperative period of 4.5 weeks (1 to 6 weeks).

CONCLUSIONS

An injectable mineral bone cement with high initial mechanical strength was used to fill bone defects in unstable tibial plateau fractures with good success. This material offers new perspectives in the treatment of tibial plateau fractures.

Transforming growth factor-beta1 incorporation in an alpha-tricalcium phosphate/dicalcium phosphate dihydrate/tetracalcium phosphate monoxide cement: release characteristics and physicochemical properties

The osteoconductive properties of calcium phosphate cements (CPCs) may be improved by the addition of growth factors, such as recombinant human transforming growth factor-beta1 (rhTGF-beta1). Previously we have shown that rhTGF-beta1 was released from cement enriched with rhTGF-beta1 and subsequently stimulated the differentiation of pre-osteoblastic cells from adult rat long bones. It is unknown whether the addition of rhTGF-beta1 changes the material properties of this alpha-tricalcium-phosphate (alpha-TCP)/tetracalcium-phosphate-monoxide (TeCP)/dicalcium-phosphate-dihydrate (DCPD) cement, and what the characteristics of the release of rhTGF-beta1 from this CPC are. Therefore, in the present study we determined the release of rhTGF-beta1 from cement pellets in vitro. The possible intervening effects of the CPC modification for intermixing rhTGF-beta1 on physicochemical properties were studied by assessing the compressive strength and setting time, as well as crystallinity, calcium to phosphorus ratio, porosity and microscopic structure. Most of the previously incorporated rhTGF-beta1 in the cement pellets was released within the first 48 h. For all concentrations of rhTGF-beta1 intermixed (100 ng-2.5 mg/g CPC), approximately 0.5% of the amount of rhTGF-beta1 incorporated initially was released in the first 2 h, increasing to 1.0% after 48 h. The release of rhTGF-beta1 continued hereafter at a rate of about 0.1% up to 1 week, after which no additional release was found. The initial setting time, nor the final setting time was changed in control cement without rhTGF-beta1 (standard CPC) or in cement modified for rhTGF-beta1 (modified CPC) at 20 degrees C and 37 degrees C. Setting times were more than six times decreased at 37 degrees C compared to 20 degrees C. The compressive strength was initially low for both standard CPC and modified CPC, after which it increased between 24 h and 8 weeks. The compressive strength for the modified CPC was significantly higher compared with standard at 1, 2, and 8 weeks after mixing. X-ray diffraction revealed that both standard and modified CPC changed similarly from the original components into crystalline apatite. The calcium to phosphorus ratio as determined by an electron microprobe did not differ at all time points measured for standard CPC and modified CPC. In both standard CPC and modified CPC the separated particles became connected by crystals, forming a structure in which the particles could hardly be recognised in a densifying matrix with some small pores. The present study shows that the calcium phosphate cement is not severely changed by modification for the addition of rhTGF-beta1. The addition of rhTGF-beta1 in CPC enhances the biologic response as shown in our previous study and did not interfere with the aimed physical and chemical properties as shown in this study. We conclude that the addition of rhTGF-beta1 enlarges the potential of the CPC in bone replacement therapy.

Transforming growth factor-beta1 incorporation in a calcium phosphate bone cement: material properties and release characteristics

The bone regenerative properties of calcium phosphate cements (CPCs) may be improved by the addition of growth factors, such as recombinant human transforming growth factor-beta1 (rhTGF-beta1). Previously, we showed that rhTGF-beta1 in CPC stimulated the differentiation of preosteoblastic cells from adult rat long bones. The intermixing of rhTGF-beta1 in CPC, which was subsequently applied to rat calvarial defects, enhanced bone growth around the cement and increased the degradation of the cement. However, it is unknown whether the addition of rhTGF-beta1 changes the material properties of CPC and what the characteristics of the release of rhTGF-beta1 from CPC are. Therefore, we determined in this study the release of rhTGF-beta1, in vitro, from the cement pellets as implanted in the rat calvariae. The possible intervening effects of rhTGF-beta1 intermixing on the clinical compliance of CPC were studied through an assessment of its compressive strength and setting time, as well as its crystallinity, calcium-to-phosphorus ratio, porosity, and microscopic structure. We prepared CPC by mixing calcium phosphate powder (58% alpha-tricalcium phosphate, 25% anhydrous dicalcium phosphate, 8.5% calcium carbonate, and 8.5% hydroxyapatite) with a liquid (3 g/mL). The liquid for standard CPC consisted of water with 4% disodium hydrogen phosphate, whereas the liquid for modified CPC was mixed with an equal amount of 4 mM hydrochloride with 0.2% bovine serum albumin. The hydrochloride liquid contained rhTGF-beta1 in different concentrations for the release experiments. Most of the rhTGF-beta1 incorporated in the cement pellets was released within the first 48 h. For all concentrations of intermixed rhTGF-beta1 (100 ng to 2.5 mg/g of CPC), approximately 0.5% was released in the first 4 h, increasing to 1.0% after 48 h. Further release was only about 0.1% from 2 days to 8 weeks. CPC modification slightly increased the initial setting time at 20 degrees C from 2.6 to 5 min but had no effect on the final setting time of CPC at 20 degrees C or the initial and final setting times at 37 degrees C. The compressive strength was increased from 18 MPa in the standard CPC to 28 MPa in the modified CPC only 4 h after mixing. The compressive strength diminished in the modified CPC between 24 h and 8 weeks from 55 to 25 MPa. No other significant change was found with the CPC modification for rhTGF-beta1. X-ray diffraction revealed that standard and modified CPCs changed similarly from the original components, alpha-tricalcium phosphate and anhydrous dicalcium phosphate, into an apatite cement. The calcium-to-phosphorus ratio, as determined with an electron microprobe, did not differ for standard CPC and modified CPC. Standard and modified CPCs became dense and homogeneous structures after 24 h, but the modified CPC contained more crystal plaques than the standard CPC, as observed with scanning electron microscopy (SEM). SEM and back- scattered electron images revealed that after 8 weeks the cements showed equally and uniformly dense structures with microscopic pores (<1 microm). Both CPCs showed fewer crystal plaques at 8 weeks than at 24 h. This study shows that CPC is not severely changed by its modification for rhTGF-beta1. The prolonged setting time of modified cement may affect the clinical handling but is still within acceptable limits. The compressive strength for both standard and modified cements was within the range of thin trabecular bone; therefore, both CPCs can withstand equal mechanical loading. The faster diminishing compressive strength of modified cement from 24 h to 8 weeks likely results in early breakdown and so might be favorable for bone regeneration. Together with the beneficial effects on bone regeneration from the addition of rhTGF-beta1 to CPC, as shown in our previous studies, we conclude that the envisaged applications for CPC in bone defects are upgraded by the intermixing of rhTGF-beta1. Therefore, the combination of CPC and rhTGF-beta1 forms a promising synthetic bone graft.

Use of injectable calcium phosphate cement for fracture fixation: a review

Injectable osteoconductive calcium phosphate cements have been introduced as an adjunct to internal fixation for treating selected fractures. These cements harden without producing much heat, develop compressive strength, and are remodeled slowly in vivo. The main purpose of the cement is to fill voids in metaphyseal bone, thereby reducing the need for bone graft, but cements also may improve the holding strength around metal devices in osteoporotic bone. Several bioactive cements are being developed. One of these cements, Skeletal Repair System, is available in Europe and has been approved by the United States Food and Drug Administration for use in selected distal radius fractures. Cadaveric studies have shown that using Skeletal Repair System cement with conventional metal fixation in certain fractures of the distal radius, tibial plateau, proximal femur, and calcaneus can produce better stability, stiffness, and strength than metal fixation alone. Early clinical results have shown reduced time to full weightbearing when cement has been used for augmentation of tibial plateau and calcaneal fractures, more rapid gain of strength and range of motion when used in distal radius fractures, and improved stability in certain hip fractures. Bioactive cements in general also may prove useful in vertebroplasty.

[Unstable fracture of the distal radius and its treatment: comparison of three techniques: external fixation, intramedullary pinning and AO plates]

This retrospective study compares 94 distal radius fractures. Sixty one women (median age 66) and 33 men (median age 42) were reviewed clinically and radiologically by a surgeon not involved in treatment. Fractures were classified into three AO groups. Standard X-rays were used for radiological evaluation. Fractures of the distal ulna were evaluated separately. Chi-square tests, Wilcoxon, Mann-Whitney and Fisher's tests were used for statistical evaluation. Women presented mainly "A" type fractures. They were treated by intramedullary pinning. Forty two fractures were grafted, using autogenous bone for young patients and bone substitute for the elderly. Twelve scapholunate dissociations were recorded, all but one were detected in women, 50 years of age or more. Four were painfree, two presented climatic pain and six claimed pain during effort; none had snapping. Radio-ulnar laxity was similar with or without styloid fractures. External fixator and autogenous grafts appeared the most efficient technique for maintaining radial length. Ulnar head fractures were related to a significant higher incidence of sympathetic dystrophy with reduced prono-supination, a correlation not previously noted to your knowledge. This suggests that radius and ulnar head fracture should be classified independently. The amount of pain was not related to classification, internal fixation or gender.

Delayed surgery does not reduce the interface strength between the surface of a bone fracture and a self-curing injectable hydroxyapatite (Norian SRS)

The shear strength of the interface between bone and an injectable calcium phosphate bone substitute that cures to form a carbonated apatite (Norian SRS) was measured and related to the time that elapsed between injury and surgery. Eleven rabbits had a 3 mm drill hole made in the retropatellar aspect of the distal femur. After one week, the rabbits were reoperated on and the hole filled with Norian SRS after it had been cleaned gently with a sponge. During the same procedure a similar hole was burred in the opposite femur and filled with Norian SRS after a few minutes ("immediate injection"). Four other rabbits had only one side operated on with immediate injection of Norian SRS to compare with the opposite untreated side. The rabbits were killed four days after the injection of Norian SRS. The femurs were prepared and sawed perpendicularly to the burr channels to produce discs 3.5 mm thick. A push out test of the Norian SRS plug within the bone disc was done to measure the force at failure. In the immediately injected specimens the failure occurred at a mean of 28 N (range 5-57) compared with 42 N (range 25-65) in the specimens injected after a one week delay. There was no significant difference between delayed and immediate treatment (95% confidence interval -5 to 133). The histological examination showed that 9 of the 12 specimens had Norian SRS still adherent to half or more of the circumference of the hole. This indicates that the failure occurred in the Norian SRS rather than in the bone or at the interface.

Radiostereometric analysis of distal radial fracture displacement during treatment: a randomized study comparing Norian SRS and external fixation in 23 patients

In a randomized study, we included 23 osteoporotic patients with a distal radial fracture and loss of reduction after 1 week. The facture was re-reduced. In one group, a self-setting hydroxyapatite, Norian SRS, was injected into the fracture and the wrist was immobilized for 2 weeks with a dorsal splint (n 12). In the other group, the fracture was immobilized for 5 weeks with an external fixator (n 11). During the operation, the fracture fragments were marked with tantalum markers, so that loss of reduction during the immobilization and after mobilization could be studied with radiostereometric analysis (RSA). We found some recurrence of compression in the fracture in both groups during immobilization. After mobilization, the motion of the fracture, measured by displacement of the fragments along the longitudinal axis, was less than 2 mm, except in 3 cases treated with Norian SRS. A compression along the longitudinal axis of less than 2 mm is not likely to cause any problem in the long term. From the first to the last investigation, 7/12 patients with Norian SRS and 4/11 with external fixation lost more than 2 mm of the reduction along the longitudinal axis. We conclude that 5 weeks of immobilization is sufficient for healing with external fixation in this age group. This immobilization time might be reduced to 2 weeks for fractures treated with Norian SRS, but additional hardware should be used to ensure stability of the fracture system.

Clinical applications of bone graft substitutes

Autogenous bone grafting remains the gold standard for osseous reconstruction in clinical practice. It is associated with several limitations. The search for an alternative bone graft substitute with combined osteoinductive, osteoconductive, and osteogenic properties continues. This article highlights the properties of the various bone grafting materials currently available and discusses their efficacy in clinical practice.

Use of an osteoconductive agent (Norian) in anterior surgical management of odontoid fractures

Odontoid fractures can be successfully treated with anterior screw fixation. Odontoid fractures commonly occur in older patients who may have significant osteopenia. The authors examined the use of a bone substitute to overcome limitations encountered during a procedure in which anterior odontoid screw fixation is performed.

Two elderly patients with displaced, reducible acute odontoid fractures underwent anterior odontoid screw fixation. The intraoperative failure of the anterior vertebral cortex from osteopenic bone and failure to achieve complete contact between the dens and axis were encountered. The defects were supplemented by using the osteoconductive agent Norian. Outcome was evaluated to determine the utility of this method.

Occasional intraoperative failure of anterior odontoid screw fixation may be encountered. Supplementation of bone defects with this osteoconductive agent may facilitate successful bone union in selected patients.