Human bone morphogenetic protein allografting for reconstruction of femoral nonunion

Bone Matrix Non-Collagenous Proteins in Tissue Engineering: Creating New Bone by Mimicking the Extracellular Matrix

Engineering biomaterials that mimic the extracellular matrix (ECM) of bone is of significant importance since most of the outstanding properties of the bone are due to matrix constitution. Bone ECM is composed of a mineral part comprising hydroxyapatite and of an organic part of primarily collagen with the rest consisting on non-collagenous proteins. Collagen has already been described as critical for bone tissue regeneration; however, little is known about the potential effect of non-collagenous proteins on osteogenic differentiation, even though these proteins were identified some decades ago. Aiming to engineer new bone tissue, peptide-incorporated biomimetic materials have been developed, presenting improved biomaterial performance. These promising results led to ongoing research focused on incorporating non-collagenous proteins from bone matrix to enhance the properties of the scaffolds namely in what concerns cell migration, proliferation, and differentiation, with the ultimate goal of designing novel strategies that mimic the native bone ECM for bone tissue engineering applications. Overall, this review will provide an overview of the several non-collagenous proteins present in bone ECM, their functionality and their recent applications in the bone tissue (including dental) engineering field.

Treatment of atrophic nonunion via autogenous ilium grafting assisted by vertical fixation of double plates: A case series of patients

OBJECTIVE

To investigate the efficacy of the treatment of atrophic nonunion using structural autogenous ilium bone grafting in combination with vertical fixation of double plates.

METHODS

This retrospective study analysed the clinical data from consecutive patients with atrophic nonunion who underwent autogenous ilium grafting in combination with double-plate vertical fixation. The injury type and the bone affected by nonunion, the duration of nonunion and the outcomes following surgery were recorded for all patients.

RESULTS

The study enrolled 43 patients with atrophic nonunion of the upper and lower limbs: 17 patients with tibial nonunion, 21 with femoral nonunion, four with humeral nonunion and one with radial shaft nonunion. The mean duration of postoperative follow-up was 14.5 months (range, 8-28 months). A total of 43 of 43 patients (100%) achieved a healed nonunion fracture without the occurrence of complications such as infection, fracture of internal fixation or pain in the harvesting site. Comprehensive postoperative assessments of bone healing and function were observed to be good and/or excellent in all 43 patients.

CONCLUSION

Structural autogenous ilium grafting used in combination with double-plate vertical fixation can provide a stable structural environment for near optimal bone healing in patients with atrophic nonunion.

Biologic Approaches to Problems of the Hand and Wrist

Orthobiologics are not used as frequently in the hand and wrist as in other sites. The most frequently reported is the use of bone morphogenetic protein for the treatment of Kienböck disease. Animal studies have described improved tendon healing with the use of platelet-rich plasma (PRP), but no clinical studies have confirmed these results. PRP has been reported to produce improvements in the outcomes of distal radial fractures and osteoarthritis of the trapeziometacarpal in small numbers of patients. The use of orthobiologics in the hand and wrist are promising, but clinical trials are necessary to establish efficacy and safety.

Treatment Options for Nonunion With Segmental Bone Defects: Systematic Review and Quantitative Evidence Synthesis

OBJECTIVES

To determine which reconstruction treatment of long bones nonunion with segmental bone defects (SBDs) is effective to restore bone length and union with good function.

DATA SOURCES

PubMed was used to identify published literature on treatment of SBD caused by fracture nonunion regardless of infection between January 1975 and December 2014.

STUDY SELECTION

We included retrospective cohort studies with a minimum sample size of 10 consecutive patients with minimum follow-up of 18 months and available data on radiographic and functional outcomes.

DATA EXTRACTION

Literature review revealed 24 publications with a sample size of 504 patients (395 males, 109 females). Data on bone union and functional outcome and complications were collected and analyzed based on validated classification systems.

DATA SYNTHESIS

Two outcome groups were categorized for bone union and functional outcome, success, and failure. We then performed heterogeneity test to examine the variability or differences in the methods used by these studies and based on that we determined whether the fixed effect or random effect method is appropriate in examining the summary or pool estimate. Pool estimate was examined for bone union and functional outcome in each surgical modality and in each anatomic location when data were available.

CONCLUSIONS

Treatment of SBD can be challenging. This quantitative evidence synthesis shows that bone union was achieved by different procedures with variable bone union and functional outcomes.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

New Bone Formation Induced by Injection of Native Reindeer Bone Morphogenetic Protein Extract

Background and Aims:

Bone morphogenetic proteins (BMPs) are usually administered with a solid framing material during open surgery. In some instances, percutaneous administration of injectable BMP would be preferable. We tested the new bone-forming activity of injectable native reindeer BMP extract in the Balb/C mouse thigh muscle pouch model.

Materials and Methods:

The injectable implants contained 6 mg of native reindeer BMP extract and either physiological saline (NaCl/BMP) or collagen (Gel/BMP). Corresponding implants without BMP served as controls. New bone formation was evaluated based on incorporation of Ca45 and radiographically three weeks after the injection into the mouse thigh muscles.

Results:

None of the injections without BMP were able to induce new bone visible in radiographs, whereas the injections with BMP induced new bone effectively. There were no significant differences in the area of new bone (p = 0.247) and its density (p = 0.739) between the NaCl/BMP and Gel/BMP groups. Ca-45 incorporation was multifold in the NaCl/BMP and Gel/BMP groups compared to the controls (p = 0.000). No significant differences in Ca-45 incorporation (p = 0.739) between the NaCl/BMP and Gel/BMP groups were observed.

Conclusion:

Our results suggest that BMP can be administered percutaneously, and that collagen and physiological saline are equally good carriers of injectable implants of native reindeer BMP.

Inkjet-based biopatterning of SDF-1β augments BMP-2-induced repair of critical size calvarial bone defects in mice

BACKGROUND

A major problem in craniofacial surgery is non-healing bone defects. Autologous reconstruction remains the standard of care for these cases. Bone morphogenetic protein-2 (BMP-2) therapy has proven its clinical utility, although non-targeted adverse events occur due to the high milligram-level doses used. Ongoing efforts explore the use of different growth factors, cytokines, or chemokines, as well as co-therapy to augment healing.

METHODS

Here we utilize inkjet-based biopatterning to load acellular DermaMatrix delivery matrices with nanogram-level doses of BMP-2, stromal cell-derived factor-1β (SDF-1β), transforming growth factor-β1 (TGF-β1), or co-therapies thereof. We tested the hypothesis that bioprinted SDF-1β co-delivery enhances BMP-2 and TGF-β1-driven osteogenesis both in-vitro and in-vivo using a mouse calvarial critical size defect (CSD) model.

RESULTS

Our data showed that BMP-2 bioprinted in low-doses induced significant new bone formation by four weeks post-operation. TGF-β1 was less effective compared to BMP-2, and SDF-1β therapy did not enhance osteogenesis above control levels. However, co-delivery of BMP-2+SDF-1β was shown to augment BMP-2-induced bone formation compared to BMP-2 alone. In contrast, co-delivery of TGF-β1+SDF-1β decreased bone healing compared to TGF-β1 alone. This was further confirmed in vitro by osteogenic differentiation studies using MC3T3-E1 pre-osteoblasts.

CONCLUSIONS

Our data indicates that sustained release delivery of a low-dose growth factor therapy using biopatterning technology can aid in healing CSD injuries. SDF-1β augments the ability for BMP-2 to drive healing, a result confirmed in vivo and in vitro; however, because SDF-1β is detrimental to TGF-β1-driven osteogenesis, its effect on osteogenesis is not universal.

A novel osteogenic oxysterol compound for therapeutic development to promote bone growth: activation of hedgehog signaling and osteogenesis through smoothened binding

Osteogenic factors are often used in orthopedics to promote bone growth, improve fracture healing, and induce spine fusion. Osteogenic oxysterols are naturally occurring molecules that were shown to induce osteogenic differentiation in vitro and promote spine fusion in vivo. The purpose of this study was to identify an osteogenic oxysterol more suitable for clinical development than those previously reported, and evaluate its ability to promote osteogenesis in vitro and spine fusion in rats in vivo. Among more than 100 oxysterol analogues synthesized, Oxy133 induced significant expression of osteogenic markers Runx2, osterix (OSX), alkaline phosphatase (ALP), bone sialoprotein (BSP), and osteocalcin (OCN) in C3H10T1/2 mouse embryonic fibroblasts and in M2-10B4 mouse marrow stromal cells. Oxy133-induced activation of an 8X-Gli luciferase reporter, its direct binding to Smoothened, and the inhibition of Oxy133-induced osteogenic effects by the Hedgehog (Hh) pathway inhibitor, cyclopamine, demonstrated the role of Hh pathway in mediating osteogenic responses to Oxy133. Oxy133 did not stimulate osteogenesis via BMP or Wnt signaling. Oxy133 induced the expression of OSX, BSP, and OCN, and stimulated robust mineralization in primary human mesenchymal stem cells. In vivo, bilateral spine fusion occurred through endochondral ossification and was observed in animals treated with Oxy133 at the fusion site on X-ray after 4 weeks and confirmed with manual assessment, micro-CT (µCT), and histology after 8 weeks, with equal efficiency to recombinant human bone morphogenetic protein-2 (rhBMP-2). Unlike rhBMP-2, Oxy133 did not induce adipogenesis in the fusion mass and resulted in denser bone evidenced by greater bone volume/tissue volume (BV/TV) ratio and smaller trabecular separation. Findings here suggest that Oxy133 has significant potential as an osteogenic molecule with greater ease of synthesis and improved time to fusion compared to previously studied oxysterols. Small molecule osteogenic oxysterols may serve as the next generation of bone anabolic agents for therapeutic development.

Osteopromotive activity of a novel pyrazole carboxamide derivative

AIMS

To investigate the effect of 1-(4-(tert-butyl)benzyl)-N-(4-methoxyphenyl)-3-phenyl-1H-pyrazole-5-carboxamide (Pyr-C) on the proliferation and osteogenic differentiation of MC3T3-E1 cells.

MATERIALS & METHODS

MTT and BrdU incorporation assay were used to determine cell survival and proliferation. The gene expression levels of osteogenic markers were determined using real-time PCR and ALP activity was detected. Western-blot analysis was used to determine the protein expression of BSP and OPN. The long-term effect of Pyr-C on mineralization deposition was measured by Alizarin Red Staining.

RESULTS

Pyr-C inhibited cell proliferation and increased ALP activity. Gene expression of ALP, BSP, OCN, Runx2, and Osterix was up-regulated in Pyr-C-induced group. Pyr-C increased the protein expression of BSP at day 7, 14 and 21, and OPN at day 14, 21 and 28. Meanwhile, Pyr-C enhanced the mineral deposition.

CONCLUSION

Pyr-C inhibits proliferation and stimulates osteogenic differentiation of MC3T3-E1 cells.

A novel arthroscopic technique utilizing bone morphogenetic protein in the treatment of Kienböck disease

Kienböck disease, first described in 1910, is osteonecrosis of the carpal lunate and has been associated with ulnar minus variance. Numerous joint leveling procedures have been developed for patients with ulnar-negative variance to decrease forces transmitted across the lunate. The basis of operative treatment is the presence or absence of advanced osteoarthritis associated with fragmentation of the carpal lunate and capitate descent. Bone morphogenetic proteins (BMPs) have been utilized successfully as adjunctive treatment in fracture healing and recently in the surgical treatment of a patient with Lichtman stage IIIA Kienböck disease. Arthroscopy is an available tool in assessing cartilage injury and coupled with the use of BMP may be of benefit in patients with ulnar-neutral or ulnar-negative wrists who have not progressed to severe arthritis and capitate descent. We report a novel arthroscopic technique in which a stage IIIA and IIIB carpal lunate osteonecrosis is treated by curettage and grafting with an admixture of autologous radial cancellous bone marrow graft and BMP-2.

BMP-2 but not VEGF or PDGF in fibrin matrix supports bone healing in a delayed-union rat model

Treatment of delayed bone healing and non-unions after fractures, osteotomies or arthrodesis still is a relevant clinical challenge. Artificially applied growth factors can increase bone healing and progressively gain importance in clinical routine. The aim of this study was to determine the effects of rhPDGF-BB, rhVEGF-165, and rhBMP-2 in fibrin matrix on bone healing in a delayed-union rat model. Thirty-seven rats underwent a first operation where a standardized femoral critical size defect was created. A silicone spacer was implanted to impair vascularization within the defect. At 4 weeks the spacer was removed in a second operation and rhPDGF-BB, rhVEGF-165, or rhBMP-2 were applied in a fibrin clot. Animals in a fourth group received a fibrin clot without growth factors. At 8 weeks fibrin bound rhBMP-2 treated animals showed a significantly increased union rate and bone volume within the defect compared to the other groups. Single application of fibrin bound rhPDGF-BB and rhVEGF-165 failed to increase bone healing in our atrophic non-union model.

Novel oxysterols have pro-osteogenic and anti-adipogenic effects in vitro and induce spinal fusion in vivo

Stimulation of bone formation by osteoinductive materials is of great clinical importance in spinal fusion surgery, repair of bone fractures, and in the treatment of osteoporosis. We previously reported that specific naturally occurring oxysterols including 20(S)-hydroxycholesterol (20S) induce the osteogenic differentiation of pluripotent mesenchymal cells, while inhibiting their adipogenic differentiation. Here we report the characterization of two structural analogues of 20S, Oxy34 and Oxy49, which induce the osteogenic and inhibit the adipogenic differentiation of bone marrow stromal cells (MSC) through activation of Hedgehog (Hh) signaling. Treatment of M2-10B4 MSC with Oxy34 or Oxy49 induced the expression of osteogenic differentiation markers Runx2, Osterix (Osx), alkaline phosphatase (ALP), bone sialoprotein (BSP), and osteocalcin (OCN), as well as ALP enzymatic activity and robust mineralization. Treatment with oxysterols together with PPARγ activator, troglitazone (Tro), inhibited mRNA expression for adipogenic genes PPARγ, LPL, and aP2, and inhibited the formation of adipocytes. Efficacy of Oxy34 and Oxy49 in stimulating bone formation in vivo was assessed using the posterolateral intertransverse process rat spinal fusion model. Rats receiving collagen implants with Oxy 34 or Oxy49 showed comparable osteogenic efficacy to BMP2/collagen implants as measured by radiography, MicroCT, and manual inspection. Histological analysis showed trabecular and cortical bone formation by oxysterols and rhBMP2 within the fusion mass, with robust adipogenesis in BMP2-induced bone and significantly less adipocytes in oxysterol-induced bone. These data suggest that Oxy34 and Oxy49 are effective novel osteoinductive molecules and may be suitable candidates for further development and use in orthopedic indications requiring local bone formation.

Local delivery of FTY720 accelerates cranial allograft incorporation and bone formation

Endogenous stem cell recruitment to the site of skeletal injury is key to enhanced osseous remodeling and neovascularization. To this end, this study utilized a novel bone allograft coating of poly(lactic-co-glycolic acid) (PLAGA) to sustain the release of FTY720, a selective agonist for sphingosine 1-phosphate (S1P) receptors, from calvarial allografts. Uncoated allografts, vehicle-coated, low dose FTY720 in PLAGA (1:200 w:w) and high dose FTY720 in PLAGA (1:40) were implanted into critical size calvarial bone defects. The ability of local FTY720 delivery to promote angiogenesis, maximize osteoinductivity and improve allograft incorporation by recruitment of bone progenitor cells from surrounding soft tissues and microcirculation was evaluated. FTY720 bioactivity after encapsulation and release was confirmed with sphingosine kinase 2 assays. HPLC-MS quantified about 50% loaded FTY720 release of the total encapsulated drug (4.5 μg) after 5 days. Following 2 weeks of defect healing, FTY720 delivery led to statistically significant increases in bone volumes compared to controls, with total bone volume increases for uncoated, coated, low FTY720 and high FTY720 of 5.98, 3.38, 7.2 and 8.9 mm(3), respectively. The rate and extent of enhanced bone growth persisted through week 4 but, by week 8, increases in bone formation in FTY720 groups were no longer statistically significant. However, micro-computed tomography (microCT) of contrast enhanced vascular ingrowth (MICROFIL®) and histological analysis showed enhanced integration as well as directed bone growth in both high and low dose FTY720 groups compared to controls.

Treatment of long bone defects and non-unions: from research to clinical practice

The treatment of long bone defects and non-unions is still a major clinical and socio-economical problem. In addition to the non-operative therapeutic options, such as the application of various forms of electricity, extracorporeal shock wave therapy and ultrasound therapy, which are still in clinical use, several operative treatment methods are available. No consensus guidelines are available and the treatments of such defects differ greatly. Therefore, clinicians and researchers are presently investigating ways to treat large bone defects based on tissue engineering approaches. Tissue engineering strategies for bone regeneration seem to be a promising option in regenerative medicine. Several in vitro and in vivo studies in small and large animal models have been conducted to establish the efficiency of various tissue engineering approaches. Neverthelsss, the literature still lacks controlled studies that compare the different clinical treatment strategies currently in use. However, based on the results obtained so far in diverse animal studies, bone tissue engineering approaches need further validation in more clinically relevant animal models and in clinical pilot studies for the translation of bone tissue engineering approaches into clinical practice.

N-formyl-methionyl-leucyl-phenylalanine (fMLP) promotes osteoblast differentiation via the N-formyl peptide receptor 1-mediated signaling pathway in human mesenchymal stem cells from bone marrow

Binding of N-formyl-methionyl-leucyl-phenylalanine (fMLP) to its specific cell surface receptor, N-formyl peptide receptor (FPR), triggers different cascades of biochemical events, eventually leading to cellular activation. However, the physiological role of fMLP and FPR during differentiation of mesenchymal stem cells is unknown. In this study, we attempted to determine whether fMLP regulates differentiation of mesenchymal stem cells derived from bone marrow. Analysis by quantitative-PCR and flow cytometry showed significantly increased expression of FPR1, but not FPR2 and FPR3, during osteoblastic differentiation. fMLP, a specific ligand of FPR1, promotes osteoblastic commitment and suppresses adipogenic commitment under differentiation conditions. Remarkably, fMLP-stimulated osteogenesis is associated with increased expression of osteogenic markers and mineralization, which were blocked by cyclosporine H, a selective FPR1 antagonist. In addition, fMLP inhibited expression of peroxisome proliferator-activated receptor-γ1, a major regulator of adipocytic differentiation. fMLP-stimulated osteogenic differentiation was mediated via FPR1-phospholipase C/phospholipase D-Ca(2+)-calmodulin-dependent kinase II-ERK-CREB signaling pathways. Finally, fMLP promoted bone formation in zebrafish and rabbits, suggesting its physiological relevance in vivo. Collectively, our findings provide novel insight into the functional role of fMLP in bone biology, with important implications for its potential use as a therapeutic agent for treatment of bone-related disorders.

Threaded screw head inserts improve locking plate biomechanical properties

OBJECTIVES

The purpose of this study was to determine if the stiffness and fatigue life of locking one third tubular plates are enhanced by placing a locking screw head to fill the empty hole of the plate. We hypothesize that both the stiffness and fatigue life of the plates will be improved at physiologically relevant loads by filling the empty center hole of each plate.

METHODS

The mechanical stiffness and fatigue life of plates with an open versus filled center hole were assessed through finite element analysis and experimentally using a synthetic bone model under four-point bending. Two plate manufacturers were evaluated, Synthes (n) and Stryker (r). Five-hole one third tubular plates were mechanically cycled with and without filling the central screw hole while load, displacement, and number of cycles were collected. Stiffness was calculated and cycles to failure and mode of failure were monitored. Five plates were evaluated for the filled (F) and open (O) configurations for the n and r plates.

RESULTS

Finite element analysis indicated that filling the hole resulted in reduction in maximum stress at the periphery of the center hole by a factor of 2.43 and 2.29 for the n and r plates, respectively. Experimentally, a fourfold improvement was observed in fatigue life of the Synthes plates when a screw head was used to fill the central screw hole (P < 0.005; nF = 45,450 cycles versus nO = 10,305 cycles). The Stryker plates reached the maximum number of cycles (1 million) without fatigue failure in both O and F configurations. Improved bending stiffness was noted for both the n and r plates when the central hole was filled compared with open. For the Stryker plate, this increase was statistically significant (P < 0.011).

CONCLUSIONS

The methodology proposed in this study for extending fatigue life and increasing stiffness of locking plates can potentially be extended to any locking plate. Adding a screw head or screw heads to open holes in locking plates adds little additional time or expense and no morbidity to the procedure but can have substantial effects on the mechanical properties of the implant, particularly in lower-profile plates that are initially less rigid and robust.

[Therapy-resistant, atrophic and septic femoral pseudarthrosis]

Non-union is a common and serious complication in orthopaedic surgery with high socioeconomic importance. In addition to conventional methods for the treatment of non-unions bone morphogenetic protein (BMP)-7 for the induction of bone tissue is available. The case report demonstrates successful treatment of a septic and atrophic femoral non-union by combination therapy with BMP-7 and autologous spongiosa graft after multiple revision surgeries.

Management of tibial non-union with tricalcium phosphate and BMP 7

We present the case of a 30-year-old woman who was referred with an established tibial non-union with a bone defect following a spiral fracture of the tibia. Initial attempts at union with intramedullary fixation and then autograft were unsuccessful. We achieved union by debriding the fibrous tissue and packing the defect with Bone Morphogenetic Protein 7 (Osigraft, Stryker, UK) and a tricalcium phosphate bone void filler (Calstrux, Stryker, UK). We did not use any additional surgical fixation and the patient was supported in an aircast boot.

A clinical study on bone formation using a demineralized bone matrix and resorbable membrane

OBJECTIVES

The purpose of this study was to evaluate new bone formation following guided bone regeneration (GBR) using a composite of demineralized cortical and nondemineralized cancellous bone admixed in a poloxamer reverse phase carrier (Orthoblast II) and resorbable collagen membrane (Ossix).

STUDY DESIGN

Fourteen patients (14 specimens) participated in this study from January 2006 to May 2006. In all these 14 patients, bone grafting for the regeneration of dehiscence defects around the implants was required. At the 4- and/or 6-month healing period, a biopsy specimen was obtained by one oral and maxillofacial surgeon. The specimens were fixed, demineralized, embedded, and sectioned by a pathologist, and histomorphometric evaluations were performed using a computer-assisted Visus Image Analysis System.

RESULTS

A high proportion of new bone formation (12.3%-78.7%) was observed during the 4- and/or 6-month healing period. Although histopathologic findings indicated that the grafted materials did not completely resorb, new bone formation and bone remodeling were observed to increase with healing time.

CONCLUSION

It was concluded from this study that the use of GBR consisting of Orthoblast II and Ossix membranes caused favorable bone formation during the 6-month healing period. Additionally, the increase in the woven bone to lamellar bone (LB/WB) ratio and the new bone to residual graft material (NB/GM) ratio observed in this 6-month study also provided evidence of increasing bony remodeling and maturity as well as the continuous resorption of the grafting materials.

The synergistic effect of autograft and BMP-7 in the treatment of atrophic nonunions

Combining autologous bone graft and recombinant human bone morphogenetic protein-7 (BMP-7) to treat long-bone fracture aseptic atrophic nonunions theoretically could promote bone healing at higher rates than each of these grafting agents separately. We retrospectively reviewed prospectively collected data on patient general characteristics, clinical outcomes, and complications over 3 years to determine the healing rates and the incidence of complications and adverse events of this "graft expansion rationale." There were 45 patients (32 male) with a median age of 43 years (range, 19-76 years). Minimum followup was 12 months (mean, 24.5 months; range, 12-65 months). There were seven humeral, 19 femoral, and 19 tibial nonunions. The median number of prior operations was two (range, 1-7). All fractures united. Clinical and radiographic union occurred within a median of 5 months (range, 3-14 months) and 6 months (range, 4-16 months), respectively. Thirty-nine (87%) patients returned to their preinjury occupation at a mean of 4.2 months (range, 3-6 months). The median visual analog scale pain score was 0.9 (range, 0-2.8; maximum 10), and the median functional score was 86 (range, 67-95; maximum 100) at the final followup. BMP-7 as a bone-stimulating agent combined with conventional autograft resulted in a nonunion healing rate of 100% in these 45 patients.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

The small molecule phenamil induces osteoblast differentiation and mineralization

Stimulation of osteoblast differentiation from mesenchymal stem cells is a potential strategy for bone repair. Bone morphogenetic proteins (BMPs) that induce osteoblastic differentiation have been successfully used in humans to treat fractures. Here we outline a new approach to the stimulation of osteoblast differentiation using small molecules that stimulate BMP activity. We have identified the amiloride derivative phenamil as a stimulator of osteoblast differentiation and mineralization. Remarkably, phenamil acts cooperatively with BMPs to induce the expression of BMP target genes, osteogenic markers, and matrix mineralization in both mesenchymal stem cell lines and calvarial organ cultures. Transcriptional profiling of cells treated with phenamil led to the identification of tribbles homolog 3 (Trb3) as a mediator of its effects. Trb3 is induced by phenamil selectively in cells with osteoblastic potential. Both Trb3 and phenamil stabilize the expression of SMAD, the critical transcription factor in BMP signaling, by promoting the degradation of SMAD ubiquitin regulatory factor 1. Small interfering RNA-mediated knockdown of Trb3 blunts the effects of phenamil on BMP signaling and osteogenesis. Thus, phenamil induces osteogenic differentiation, at least in part, through Trb3-dependent promotion of BMP action. The synergistic use of small molecules such as phenamil along with BMPs may provide new strategies for the promotion of bone healing.

Treatment of rabbit femoral defect by firearm with BMP-4 gene combined with TGF-beta1

BACKGROUND

Firearm bone fractures are difficult to treat compared with general ones as both soft tissue and bone are injured more extensively and severely with contamination in the wound track. The bone morphogenetic protein (BMP) and transforming growth factor (TGF)-beta play an important role in bone fracture healing. Therefore, BMP-4 combined with TGF-beta1 was used to improve and accelerate the repair of rabbit femoral defect resulting from firearm.

METHODS

Femoral defect was made with 0.375 g steel ball fired at 350 m/s. At 6 hours after wounding, the debridement and irrigation were performed, followed by trimming the ends of defected bone at day 7. Plasmid-encoded BMP-4 gene identified in vitro and TGF-beta1 were injected into the tissue of upper and lower parts and the epicenter of the defected area at 2 weeks after wounding, again TGF-beta1 was given at 5 weeks. At 3, 7, 11, and 15 weeks after wounding, the expression of mRNA and protein of BMP-4 were detected by reverse transcription-polymerase chain reaction and Western blot. The activity of alkaline phosphatase and calcium content were measured for describing osteogenetic ability. The course and quality of osteogenesis were determined quantitatively by pathohistological and X-ray examinations.

RESULTS

In vivo BMP-4 mRNA and protein could be continually expressed for 8 weeks. The determination of alkaline phosphatase activity and calcium content showed osteogenetic ability was significantly enhanced by BMP-4 gene combined with TGF-beta1. The pathohistological and X-ray examinations revealed that osteogenetic speed was prominently accelerated, and the quality was improved after the treatment.

CONCLUSION

The repair of rabbit femoral defect resulting from firearm can be significantly improved and accelerated by BMP-4 gene combined with TGF-beta1.

Cellular-based therapy for osteonecrosis

This review article describes bone remodeling in the context of osteonecrosis as a bone disease, the use of stem cells in bone and vascular diseases, and cellular therapy in osteonecrosis.

Bone morphogenetic proteins in total hip arthroplasty, osteonecrosis and trauma surgery

This review provides an overview of the use of bone morphogenetic proteins to enhance bone healing and bone graft incorporation in difficult defects created from failed total hip arthroplasties, osteonecrosis of the femoral head and trauma. Multiple publications have demonstrated that bone morphogenetic proteins are osteoinductive in preclinical trials (i.e., animal models); however, there is controversy and limited understanding of the use of this technology in orthopedic surgical practice. The question remains as to whether they are useful in difficult fractures, nonunions and large defects created from failed total hip arthroplasty or femoral head osteonecrosis. There might be a small risk for infection by the process of introducing foreign materials in a clinical situation, but this has not yet been realized to date. In addition, these materials offer an advantage in large defects where there is not enough transplantable material available from the host. We believe that the use of these materials will become more widespread with newer carriers, minimally invasive applications and diminished commercial costs.

Bone morphogenetic protein as an adjuvant in the treatment of Kienbock's disease by vascular pedicle implantation

This case report documents the first use of bone morphogenetic protein (BMP) as an adjuvant to revascularisation with a first dorsal metacarpal arterio-venous pedicle in the treatment of a patient with Stage III Kienbock's disease. The patient had complete relief of her symptoms of wrist pain by 8 months postoperatively, when X-rays showed no further evidence of lunate collapse and an MRI scan demonstrated islands of revascularisation. It is impossible to prove unequivocably that BMP contributed to the result seen in this one patient, but this adjuvant concept is based on experimental evidence demonstrating that optimal bioengineering of vascularised bone is dependent on four factors - a structural matrix, progenitor cells, BMP and a vascular supply, and BMP may play a future role in promoting new bone formation in Kienbock's disease.

Oxysterols enhance osteoblast differentiation in vitro and bone healing in vivo

Oxysterols, naturally occurring cholesterol oxidation products, can induce osteoblast differentiation. Here, we investigated short-term 22(S)-hydroxycholesterol + 20(S)-hydroxycholesterol (SS) exposure on osteoblastic differentiation of marrow stromal cells. We further explored oxysterol ability to promote bone healing in vivo. Osteogenic differentiation was assessed by alkaline phosphatase (ALP) activity, osteocalcin (OCN) mRNA expression, mineralization, and Runx2 DNA binding activity. To explore the effects of osteogenic oxysterols in vivo, we utilized the critical-sized rat calvarial defect model. Poly(lactic-co-glycolic acid) (PLGA) scaffolds alone or coated with 140 ng (low dose) or 1400 ng (high dose) oxysterol cocktail were implanted into the defects. Rats were sacrificed at 6 weeks and examined by three-dimensional (3D) microcomputed tomography (microCT). Bone volume (BV), total volume (TV), and BV/TV ratio were measured. Culture exposure to SS for 10 min significantly increased ALP activity after 4 days, while 2 h exposure significantly increased mineralization after 14 days. Four-hour SS treatment increased OCN mRNA measured after 8 days and nuclear protein binding to an OSE2 site measured after 4 days. The calvarial defects showed slight bone healing in the control group. However, scaffolds adsorbed with low or high-dose oxysterol cocktail significantly enhanced bone formation. Histologic examination confirmed bone formation in the defect sites grafted with oxysterol-adsorbed scaffolds, compared to mostly fibrous tissue in control sites. Our results suggest that brief exposure to osteogenic oxysterols triggered events leading to osteoblastic cell differentiation and function in vitro and bone formation in vivo. These results identify oxysterols as potential agents in local and systemic enhancement of bone formation.

Staged-injection procedure to prevent cement leakage during vertebroplasty: an in vitro study

STUDY DESIGN

Fibrin sealant (FS) combined with or without growth factor was used to improve the micro-architectural and biomechanical properties of vertebral body in osteoporotic ovine spine.

OBJECTIVE

To analyze the treatment effects of bovine bone morphogenetic protein (bBMP) combined with FS on osteopenic ovine vertebral architecture, bone mineral density, and biomechanics in vivo.

SUMMARY OF BACKGROUND DATA

Vertebroplasty and kyphoplasty were used to treat spinal osteoporosis. They can increase strength of vertebrae physically. However, each has specific disadvantages. bBMP could rapidly increasing bone formation and suppressing bone resorption, but little is known about its effect on ovariectomized-induced osteoporosis.

METHODS

Six sheep underwent ovariectomy and were placed on a low-calcium diet. Twelve months later, according to Ladin square design, L4-L6 vertebrae in all sheep were randomly assigned to 3 treatment groups: A (30 mg bBMP/1.5 mL FS), B (30 mg bBMP) and C (1.5 mL FS). All materials were injected into the assigned vertebra transpedicularly. Animals were killed 3 months after injection, and bone mineral density (BMD), biomechanics, and histomorphometry were assessed. Analysis of variance was used to determine effects of bBMP/FS (alpha = 0.05).

RESULTS

The BMD in Group 1 was 17.1% and 14.7% higher than that in Group 2 and Group 3, respectively. The micro-CT reconstruction analysis showed that the density and connectivity of trabecular bone in bBMP/FS treated vertebrae were higher than those in control groups. The mechanical properties (yield stress, ultimate stress, energy absorption, bone modulus) of the vertebrae were also significantly higher. In this study, local bBMP/FS treatment showed a positive trend in improving BMD, histomorphometric parameters, and mechanical strength of osteoporotic vertebra. Slow release of bBMP using FS appeared to be an effective method of protein delivery.

CONCLUSION

The use of bBMP/FS in the treatment of vertebral osteoporosis in an attempt to enhance bone strength merits further study.

A study of the role of nell-1 gene modified goat bone marrow stromal cells in promoting new bone formation

Nell-1 is a recently discovered secreted protein with the capacity to promote osteoblastic calvarial cell differentiation and mineralization and induce calvarial bone overgrowth and regeneration in various rodent models. However, the extent of Nell-1 osteoinductivity in large animal cells remains unknown. The objective of the study was to evaluate the feasibility of adenoviral encoding Nell-1 (AdNell-1) gene transfer into primary adult goat bone marrow stromal cells (BMSCs) in vitro and in vivo and to compare the osteoinductive effects with those produced by bone morphogenetic protein-2 (BMP-2), a well established osteoinductive molecule currently utilized for regional gene therapy. AdNell-1-transduced BMSCs expressed Nell-1 protein and underwent osteoblastic differentiation within 2 weeks in vitro, which is comparable to AdBMP-2. After intramuscular injection of nude mice, the AdNell-1- and AdBMP-2-transduced BMSCs revealed new bone formation, while untransduced or AdLacZ-transduced BMSCs showed mainly fibrotic tissue proliferation. At 4 weeks, BMP-2 induced significantly larger bone mass with a mature bone margin and central cavity filled with primarily fatty marrow tissue. Nell-1 samples had significantly less bone mass but were histologically similar to newly formed trabecular bone mixed with chondroid bone-like areas verified by type X collagen (ColX) immunohistochemistry. This distinct difference in histomorphology from the bone mass induced by BMP-2 suggests that there is a potential clinical role/advantage for Nell-1 in skeletal tissue engineering and regeneration.

Grafting for periprosthetic femoral fractures: strut, impaction or femoral replacement

Peri-prosthetic fractures are technically demanding to treat, as they require the skills of revision arthroplasty as well as those of trauma surgery. [Lindahl H, Malchau H, Herberts P, Garellick G. Periprosthetic femoral fractures classification and demographics of 1049 periprosthetic femoral fractures from the Swedish National Hip Arthroplasty Register. J Arthroplasty 2005;20:857-65.] reporting on 1049 periprosthetic femoral fractures found that the annual incidence varied between 0.045% and 0.13% for all THAs performed in Sweden and that the accumulated incidence for the primary hip arthroplasties was 0.4% while for the revision arthroplasties was 2.1% [Lindahl H, Malchau H, Herberts P, Garellick G. Periprosthetic femoral fractures classification and demographics of 1049 periprosthetic femoral fractures from the Swedish National Hip Arthroplasty Register. J Arthroplasty 2005;20:857-65.]. The elderly population is particularly vulnerable to low energy periprosthetic fractures attributed to osteopenia or osteoporosis leaving limited reconstruction options to the hip revision surgeon. Bone grafting in the form of autograft has well recognized limitations and allograft represents the gold standard of bone augmentation in the majority of the cases. Allograft can be used as morselised in the form of impaction grafting, reconstructing the bone from within out, or in the form of structural allograft. In the latter case, strut onlay plates or whole proximal femoral allografts can be used to augment the deficient bone or to totally replace it respectively. Immune reaction and disease transmission along with delayed revascularization of the cortical allograft can cause failure of the construct in the long term; however, the results to date from their use are promising. We here present an overview of the literature on the use of available bone grafts in the treatment of periprosthetic femoral fractures.

Biological enhancement of tibial diaphyseal aseptic non-unions: the efficacy of autologous bone grafting, BMPs and reaming by-products

The mandatory stimulus that can optimise the healing pathway can be electrical, mechanical, biological, or a combination of all these parameters. A variety of means has been utilised for biological enhancement, including extracorporeal shock wave, electrical, ultrasound stimulation, the reaming technique of IM nailing, bone graft substitutes, osteogenic cells and bioactive molecules produced by tissue engineering techniques. The aim of this study is to present a review of the existing evidence for the efficacy of reaming, autologous bone grafting and the commercially available growth factors (BMP-2 and BMP-7) for the treatment of aseptic tibial non-unions. The gold standard method of enhancing bone healing in cases of tibial non-union remains the autologous bone graft. Autogenous bone grafts possess osteoconductive, osteoinductive properties and also osteoprogenitor cells. However, their harvesting is associated with high morbidity and many complications reaching percentages of 30%. Intramedullary reamed nailing, either used as an alternative fixation method or as an exchange to a wider implant, offers the unique biomechanical advantages of an intramedullary device, together with the osteoinductive stimulus of the by-products of reaming, and the aptitude for early weight-bearing and active rehabilitation. The safety of administration of the commercial distributed growth factors (BMP-2 and BMP-7), combined with the lack of the morbidity and the quantity restrictions that characterise autologous bone grafts, have given to this family of molecules a principal role between the other bone graft substitutes. On average the union rates reported in the 20 manuscripts that have been evaluated range from 58.3% to 100%, and the average time to union from 12.5 weeks to 48.4 weeks, indicating the significant discrepancies in the reported evidence and the multiplicity of different treatment strategies.

New technologies for the enhancement of skeletal repair

Although fracture healing is a well-optimized biological process that leads to healing, approximately 10-20% of fractures result in impaired or delayed healing and these fractures may benefit from the use of biotechnologies to enhance skeletal repair. Peptide signaling molecules such as the bone morphogenetic proteins have been shown to stimulate the healing of fresh fractures, nonunions, and spinal fusions and side effects from their use appear to be minimal. Other growth factors currently being studied for local application include growth and differentiation factor-5 (GDF-5), vascular endothelial growth factor (VEGF), transforming growth factor beta (TGFbeta), and platelet-derived growth factor (PDGF). Molecules such as prostaglandin E receptor agonists and the thrombin-related peptide, TP508, have shown promise in animal models of fracture repair. Gene therapy using various growth factors or combinations of factors might also aid in fracture repair, particularly as new methods for delivery that do not require viral vectors are developed. Systemic therapy with agents such as parathyroid hormone (PTH), growth hormone (GH), and the HMG-CoA reductase inhibitors are also under investigation. As these and other technologies are shown to be safe and effective, their use will become a part of the standard of care in managing skeletal injuries.

Results of free vascularized fibula grafting for allograft nonunion after limb salvage surgery for malignant bone tumors

The purpose of this study was to assess the results of free vascularized fibula grafting (FVFG) in the treatment of allograft fracture nonunion after limb salvage surgery for malignant bone tumors.A retrospective study was performed on 8 patients who underwent FVFG for allograft fracture nonunions. All had prior tumor resection and allograft reconstruction for osteosarcoma (n = 6) or Ewing sarcoma (n = 2) of the femur (n = 3), tibia (n = 2), humerus (n = 2), or ulna (n = 1). All patients failed an initial course of immobilization; 4 patients failed prior open reduction and internal fixation with autogenous nonvascularized bone grafting. Average age at the time of FVFG was 14 years. Average follow-up was 44 months. The FVFG resulted in successful bony healing in 7 of 8 patients, providing pain relief, limb preservation, and restoration of function. One patient developed an infection requiring fibula removal and staged prosthetic reconstruction. Additional complications requiring further treatment included limb-length discrepancy, additional allograft fracture, and wound infection. The FVFG is an effective treatment option for allograft nonunion after limb salvage surgery because it provides both the mechanical stability and biological stimulus for bony healing. Attention to internal fixation, limb alignment, and microvascular principles is essential to prevent complications and allow for the best functional outcomes.

Reconstruction of Mandibular Defects Using Autografts Combined With Demineralized Bone Matrix and Cancellous Allograft

Facial bone defects can be managed by a variety of means, such as inlay or onlay applied nonvascularized bone grafts, local pedicled/distal free osteocutaneous/osseous flaps or distraction osteogenesis. Although each method has its own advantages and drawbacks, the indications of using these methods may overlap in certain clinical situations. The use of nonvascularized bone grafts, conceptually and technically simple method, relies on creeping substitution of applied graft with regenerating new bone. However, using vascularized osteocutaneous free flaps provide not only plenty of bony tissue for reconstruction, but also soft tissue coverage over the reconstructed bony segment. Furthermore, bone healing in vascularized osteocutaneous free flaps resembles as the physiologic fracture healing. In selected cases with enough soft tissue coverage over the defective bony segment, on the other hand, using larger nonvascularized bone grafts with osteoinductive growth factors may decrease the risk of graft failure while avoiding the drawbacks of the free tissue transfer. Here we present our results of three cases with facial bone defects, to which nonvascularized iliac bone grafts and demineralized bone matrix with cancellous allograft (Orthoblast II) as a source of BMP were used together for mandibular reconstruction.

A comparison of two biomaterial carriers for osteogenic protein-1 (BMP-7) in an ovine critical defect model

Critical size defects in ovine tibiae, stabilised with intramedullary interlocking nails, were used to assess whether the addition of carboxymethylcellulose to the standard osteogenic protein-1 (OP-1/BMP-7) implant would affect the implant's efficacy for bone regeneration. The biomaterial carriers were a 'putty' carrier of carboxymethylcellulose and bovine-derived type-I collagen (OPP) or the standard with collagen alone (OPC). These two treatments were also compared to "ungrafted" negative controls. Efficacy of regeneration was determined using radiological, biomechanical and histological evaluations after four months of healing. The defects, filled with OPP and OPC, demonstrated radiodense material spanning the defect after one month of healing, with radiographic evidence of recorticalisation and remodelling by two months. The OPP and OPC treatment groups had equivalent structural and material properties that were significantly greater than those in the ungrafted controls. The structural properties of the OPP- and OPC-treated limbs were equivalent to those of the contralateral untreated limb (p > 0.05), yet material properties were inferior (p < 0.05). Histopathology revealed no residual inflammatory response to the biomaterial carriers or OP-1. The OPP- and OPC-treated animals had 60% to 85% lamellar bone within the defect, and less than 25% of the regenerate was composed of fibrous tissue. The defects in the untreated control animals contained less than 40% lamellar bone and more than 60% was fibrous tissue, creating full cortical thickness defects. In our studies carboxymethylcellulose did not adversely affect the capacity of the standard OP-1 implant for regenerating bone.

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.

Recombinant human osteogenic protein-1 induces bone formation in a chronically infected, internally stabilized segmental defect in the rat femur

BACKGROUND

Recombinant human osteogenic protein-1 (rhOP-1), combined with a collagen carrier, has been shown to induce new-bone formation in a variety of animal models. The purpose of the present investigation was to test the hypotheses that rhOP-1 would accelerate bone formation in an internally stabilized, chronically infected, critical-size defect in the rat femur and that this effect would be enhanced by the administration of systemic antibiotic.

METHODS

A 6-mm segmental defect was created surgically, stabilized with a polyacetyl plate and six Kirschner wires, and contaminated with 10(4) colony-forming units of Staphylococcus aureus in one femur in each of 168 Sprague-Dawley rats. After two weeks, these infected defects were débrided surgically and were assigned to one of six treatment groups. The defects in the thirty animals in the first group received lyophilized collagen carrier mixed with 200 microg of rhOP-1 dissolved in buffer, the defects in the thirty animals in the second group received carrier with 20 microg of rhOP-1 in buffer, and the defects in the twenty-four control animals in the third group received carrier mixed with buffer without rhOP-1. The last three groups were treated identically to the first three groups, except that the animals also received the antibiotic ceftriaxone for twenty-eight days after débridement. The animals were killed at two, four, eight, or twelve weeks after débridement. Newly mineralized callus within the defect, and adjacent to and bridging the outside of the defect, was assessed with use of quantitative high-resolution radiography, microcomputed tomography, torsional failure testing, and histological analysis of undecalcified sections.

RESULTS

Bacterial cultures confirmed the presence of a chronic infection during the study period in all animals. At the later time-points, significantly more newly mineralized callus was present within and adjacent to the débrided defects that had been treated with 200 microg of rhOP-1, whereas minimal amounts of callus were present within and adjacent to the defects that had been treated without rhOP-1 and with 20 microg of rhOP-1. At eight and twelve weeks after débridement, there was significantly more newly mineralized callus in the group that had been treated with 200 microg of rhOP-1 with antibiotic than in the group that had been treated with 200 microg of rhOP-1 without antibiotic (p < 0.05). At twelve weeks, the values for torque, energy to failure, and linear stiffness for femora that had been treated with 200 microg of rhOP-1 with antibiotic were not significantly different from the values for intact, contralateral control femora, whereas the values for femora that had been treated with 200 microg of rhOP-1 without antibiotic remained significantly lower than those for the intact, contralateral controls (p < 0.05).

CONCLUSIONS

Recombinant human osteogenic protein-1 maintained its osteoinductive capability in the presence of chronic infection, and this property was enhanced by antibiotic therapy. No substantial callus formed in the infected defects without a sufficiently high dose of rhOP-1.

CLINICAL RELEVANCE

The treatment of an infection at the site of a fracture often necessitates removal of internal fixation. However, internal fixation is needed for fracture stability. This study presents an intervention that may accelerate fracture-healing in the presence of infection and colonized hardware, thereby permitting earlier removal of the hardware and more timely and effective treatment of the infection.

Use of bone morphogenetic proteins in traumatology

An estimated 5-10% of all fractures show impaired healing, leading to delayed union, or non-union. Chemical, or physical methods to accelerate bone healing are of great interest to the orthopaedic and trauma community. Research over the last 20 years has established that successful fracture healing is steered by specific growth factors. Of these, the bone morphogenetic proteins (BMPs) are probably the most important. The signalling pathway of these proteins is tightly regulated, overseeing a finely orchestrated cascade of events that occur after a fracture. The promising results of BMPs in preclinical studies have recently cleared the way for their use in specific fractures, or non-unions in clinical practice. The purpose of this work is to give a brief overview of BMPs and to review the clinical data currently available on the use of BMPs in fracture healing.

Critical analysis and efficacy of BMPs in long bones non-union

Non-union of long bone fractures is considered as multifactorial. The management of this entity continues to be difficult often requiring multiple procedures with unpredictable results. Bone morphogenetic proteins (BMPs) are power agents being used in the clinical setting for a variety of pathological conditions where tissue regeneration is required. This article analyses the currently existing evidence of the efficacy of BMPs for the management of non-union of long bone fractures.

Classification of non-union

A substantial number of experimental and clinical studies have established that the cornerstones for successful bone-healing are biomechanical stability and biological vitality of the bone, as they both provide an environment in which new bone can be formed. Non-union of long bones is a significant consequence in treating fractures. Many approaches to prevent fracture non-union have been proposed. Depending on the type and location of the non-union, treatment options include various types of bone fixation, with or without supplemental bone graft or other biophysical enhancements.

Osteoinductivity of partially purified native ostrich (Struthio camelus) bone morphogenetic protein: Comparison with mammalian species

Bone morphogenetic proteins (BMPs) are members of the TGF-beta superfamily. They are capable of inducing ectopic bone formation. Until now, the main interest has been focused on mammalian osteoinductive BMPs, and there are no reports of native BMP extracts of birds. In this study, we isolated and characterized native BMPs of ostrich (Struthio camelus) and compared them with identically isolated native bovine (cow) and reindeer BMPs with regard to BMP pattern and osteoinductive capacity. The ostrich BMP pattern differed markedly from that of cow and reindeer BMP in non-reduced SDS-PAGE, reduced SDS-PAGE and Western blot. The differences in isoelectric focusing analysis were smaller. However, the ostrich BMP extract had a peak at pH 5.1, clearly differing from the BMPs of cow and reindeer. The osteoinductive capacity and density of ectopic bone, induced by BMP extracts in a mouse thigh muscle pouch, were determined radiographically. The ostrich BMP extract displayed significantly lower osteoinductive capacity and density of induced bone than the bovine and reindeer BMP extracts. In conclusion, our results indicate that the BMP pattern of birds differs considerably from that of mammals, and that the osteoinductive capacity of BMPs and the density of induced bone are lower in birds than in mammals. They also suggest that the bone metabolism of birds is adapted to make light bones suitable for flying.

Treatment of femoral nonunions by using cyclic compression and distraction

Eleven patients with femoral diaphyseal nonunions after intramedullary nailing were treated with cyclic compression and distraction with an external fixator over the nail. We evaluated the limitations of this technique and whether patients having this closed procedure could achieve union without additional operative procedures. Patients with hypertrophic nonunions (n = 4) were treated with gradual compression of the nonunion site. Cyclic compression and distraction was done in patients with oligotrophic (n = 2) or atrophic nonunions (n = 5) to stimulate consolidation. The average age of the patients was 32.9 years (range, 21-48 years), and the average followup was 40.5 months (range, 24-64 months). Union was achieved in an average of 5.8 months in all patients after one operation and without additional surgical intervention. However, pain necessitating strong analgesic agents and pin-related complications consisting of osteomyelitis, septic arthritis, and pin breakage in the atrophic nonunion group were a major limitation of this technique. Based on our study, the cyclic compression and distraction technique can be used in hypertrophic and oligotrophic nonunions that have failed one or more prior exchange nailings. However, it might not be an option for treatment of patients with atrophic nonunions unless pin-site problems are resolved.

LEVEL OF EVIDENCE

Therapeutic study, Level IV (case series--no, or historical control group). See the Guidelines for Authors for a complete description of levels of evidence.

Healing of a scaphoid nonunion using human bone morphogenetic protein

A chronic nonunion of a proximal pole fracture of the scaphoid was treated by curettage of the nonunion, single K-wire fixation, and implantation of 50 mg of human bone morphogenetic protein followed by 12 weeks of cast immobilization without any conventional corticocancellous bone grafting or rigid screw fixation. Radiographs showed signs of bony healing by 12 weeks and a magnetic resonance imaging scan 6 years after surgery showed no signs of avascular necrosis. The potential future applications of human bone morphogenetic protein in hand surgery are discussed.