Inhibited Callus Formation Research Articles

Dynamic Locked Plating Using Near-Cortical Over-Drilling versus Standard Locked Plating for Fixation of Lower Femur Fractures

Abstract Background Fracture Healing in distal femoral fractures is greatly influenced by fixation method. Classic compression plate requires creation of a rigid plate/bone construct which involves soft-tissue stripping and devitalization of the underlying bone, this may lead to inhibited callus formation. Hence, the concept of “Dynamic” Locked Plates has been proposed to decrease construct stiffness and improve callus formation. Aim of the Work To compare functional and radiological outcomes in lower femur fractures treated by dynamic locked plating (using near cortical over drilling) to that treated by standard locked plating. Patients and Methods Prospective study was conducted starting from May 2020 to January 2023 including 30 patients aged from 18 to 65 years old with distal femur fracture treated by dynamic locked plating with near cortex over drilling (15 patients) or standard locked plating (15 patients). We excluded patients with open fractures, periprosthetic fractures, floating knee injuries and poly-traumatized patients. The follow up period was 1 year. Results The current study demonstrated no statistically significant difference between both groups regarding time of union, knee range of motion, nonunion rate, or other specific complications. However, the DLP group was noted to have statistically significant higher callus scores at six weeks postoperative (p value = 0.015) indicating increased callus formation. Conclusion Dynamic locked plating seems to result in improved callus formation and bone healing without sacrificing fixation strength compared with traditional locked plating when used for fractures of the distal femur.

Auxin-Induced WUSCHEL-RELATED HOMEOBOX13 Mediates Asymmetric Activity of Callus Formation upon Cutting.

Plants have the regenerative ability to reconnect cut organs, which is physiologically important to survive severe tissue damage. The ability to reconnect organs is utilized as grafting to combine two different individuals. Callus formation at the graft junction facilitates organ attachment and vascular reconnection. While it is well documented that local wounding signals provoke callus formation, how callus formation is differentially regulated at each cut end remains elusive. Here, we report that callus formation activity is asymmetrical between the top and bottom cut ends and is regulated by differential auxin accumulation. Gene expression analyses revealed that cellular auxin response is preferentially upregulated in the top part of the graft. Disruption of polar auxin transport inhibited callus formation from the top, while external application of auxin was sufficient to induce callus formation from the bottom, suggesting that asymmetric auxin accumulation is responsible for active callus formation from the top end. We further found that the expression of a key regulator of callus formation, WUSCHEL-RELATED HOMEOBOX 13 (WOX13), is induced by auxin. The ectopic callus formation from the bottom end, which is triggered by locally supplemented auxin, requires WOX13 function, demonstrating that WOX13 plays a pivotal role in auxin-dependent callus formation. The asymmetric WOX13 expression is observed both in grafted petioles and incised inflorescence stems, underscoring the generality of our findings. We propose that efficient organ reconnection is achieved by a combination of local wounding stimuli and disrupted long-distance signaling.

Comparative transcriptome analysis reveals molecular regulators underlying pluripotent cell induction and callus formation in Anthurium andraeanum “Alabama”

Shoot regeneration from pluripotent cell masses is an important process for genetic improvement of Anthurium andraeanum through Agrobacterium-mediated transformation. However, the mechanisms underlying pluripotent cell induction are not well understood. Here, three half-leaf explant samples collected after 0-, 2-, and 30-d culture on callus-inducing medium were used for RNA isolation and transcriptome profiling. In total, 225,752 non-redundant unigenes were assembled with a mean length of 1299 bp. Differentially expressed genes among the three samples were identified by comparative transcriptome analysis. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed the greatest number of differentially expressed genes in the comparison between 0- and 2-d cultures were related to the “ribosome.” Many differentially expressed genes in the comparison between 2- and 30-d cultures were involved in “plant hormone signal transduction,” “starch and sucrose metabolism,” and “phenylpropanoid biosynthesis.” Further investigation was focused on genes related to transcription factors, epigenetic regulation, nitrous oxide metabolism, and homeostasis of plant hormones auxin, cytokinin, brassinolide, and strigolactone. Experiments were designed to confirm the effects of nitrous oxide and strigolactone on callus formation in Anthurium andraeanum. Callus formation was enhanced by exogenous application of sodium nitroprusside, which produces nitrous oxide, but was inhibited under rac-GR24 (a strigolactone analogue) treatment. Our comparative transcriptome analysis revealed that the signal molecule nitrous oxide and plant hormones auxin, cytokinin, and brassinolide act as positive regulators in promoting callus formation, while strigolactone may inhibit callus formation. Transcriptional and epigenetic regulations also play important roles in pluripotent cell induction in Anthurium andraeanum.

Fungal pathogens of canker disease trigger canopy dieback in poplar saplings by inducing functional failure of the phloem and cambium and carbon starvation in the xylem

Tree canker diseases are mainly caused by necrotrophic fungal pathogens, which induce canker lesions, wilting, or dieback in many species. We hypothesized that canker-associated canopy dieback is related to functional failure of the phloem and cambium, carbon starvation and/or hydraulic failure. Using a girdling and inoculation system, we evaluated gas exchange and hydraulic parameters, concentrations of non-structural carbohydrates (NSCs), leaf characteristics, stem phenotyping and symptoms of 6-month-old poplar saplings with Botryosphaeria or Valsa canker disease. Pathogen inoculations inhibited callus formation and phloem regeneration and altered the physiological parameters, water potential, NSC content in stems, and symptoms on leaves and stems, while the girdling-only control did not. Results suggest that the functional and structural integrity of the phloem and cambium play crucial roles in the pathogenesis of canker disease. Botryosphaeria canker decreased photosynthetic rate (−54% to −75%), stomatal conductance (−71% to −80%) and transpiration rate (−58% to −66%), while Valsa canker decreased photosynthetic rate (−53% to −83%), stomatal conductance (−71% to −87%) and transpiration rate (−53% to −76%) at 20, 25, and 30 days after inoculation. Results suggest that the two fungal pathogens induce carbon starvation by inhibiting photosynthesis. The leaf water potential was higher and the change in specific hydraulic conductivity was smaller in the canker region than in the adjacent regions, while the NSC content was lower in the region below cankers than above them, suggesting that the fungal pathogens caused poplar canopy dieback by initially inducing carbon starvation, not hydraulic failure.

OsHDA710-Mediated Histone Deacetylation Regulates Callus Formation of Rice Mature Embryo.

Histone deacetylases (HDACs) play important roles in the regulation of eukaryotic gene expression. The role of HDACs in specialized transcriptional regulation and biological processes is poorly understood. In this study, we evaluated the global expression patterns of genes related to epigenetic modifications during callus initiation in rice. We found that the repression of HDAC activity by trichostatin A (TSA) or by OsHDA710 mutation (hda710) results in impaired callus formation of rice mature embryo and increased global histone H3 acetylation levels. The HDAC inhibition decreased auxin response and cell proliferation in callus formation. Meanwhile, the transcriptional repressors OsARF18 and OsARF22 were upregulated in the callus of hda710. The chromatin immunoprecipitation-quantitative PCR (ChIP-qPCR) analysis demonstrated that the callus of hda710 exhibited enhanced histone H3 acetylation levels at the chromatin regions of OsARF18 and OsARF22. Furthermore, we found that OsARF18 and OsARF22 were regulated through OsHDA710 recruitment to their target loci. In addition, overexpression of OsARF18 decreased the transcription of downstream genes PLT1 and PLT2 and inhibited callus formation of the mature embryo. These results demonstrate that OsHDA710 regulates callus formation by suppressing repressive OsARFs via histone deacetylation during callus formation of rice mature embryo. This indicates that OsHDA710-mediated histone deacetylation is an epigenetic regulation pathway for maintaining auxin response during cell dedifferentiation.

MYB94 and MYB96 additively inhibit callus formation via directly repressing LBD29 expression in Arabidopsis thaliana

Plant somatic cells can be reprogrammed during in vitro culture. Callus induction is the initial step of a typical plant regeneration system. Recent studies showed that auxin-induced callus formation in multiple organs occurs from the pericycle or pericycle-like cells via a root developmental pathway. However, the molecular control of callus formation is largely unknown. Here, two MYB transcription factors, MYB94 and MYB96, were shown to play negative roles in auxin-induced callus formation in Arabidopsis. MYB94 and MYB96 were expressed in the newly formed callus. myb96, myb94, and myb94 myb96 generated more calli than the WT, with myb94 myb96 producing the most. MYB94 and MYB96 repressed expression of LATERAL ORGAN BOUNDARIES-DOMAIN 29 (LBD29) via directly binding to the gene’s promoter. The loss of function of LBD29 partly rescued the callus formation defect of myb94 myb96. Our findings found MYB94 and MYB96 to be important repressors of callus formation and MYB94/96-LBD29 as a new regulatory pathway acting in parallel with ARF7/19-LBDs’ pathway to modulate in vitro callus formation.

Genome‐wide association study of callus induction variation to explore the callus formation mechanism of rice

Rice (Oryza sativa) is one of the most widely cultivated food crops, worldwide. Tissue culture is extensively used in rice breeding and functional genome research. The ability to induce callus determines whether a particular rice variety can be subjected to tissue culture and Agrobacterium-mediated transformation. Over the past two decades, many quantitative trait loci (QTLs) related to callus induction traits have been identified; however, individual genes associated with rice callus induction have not been reported. In this study, we characterized three callus-induction traits in a global collection of 510 rice accessions. A genome-wide association study of the rice population in its entirety as well as subpopulations revealed 21 significant loci located in rice callus induction QTLs. We identified three candidate callus induction genes, namely CRL1, OsBMM1, and OsSET1, which are orthologs of Arabidopsis LBD17/LBD29, BBM, and SWN, respectively, which are known to affect callus formation. Furthermore, we predicted that 14 candidate genes might be involved in rice callus induction and showed that RNA interference (RNAi)-mediated disruption of OsIAA10 inhibited callus formation on tissue culture medium. Embryo growth in the OsIAA10 RNAi line was not inhibited by synthetic auxin (2,4-D) treatment, suggesting that OsIAA10 may perceive auxin and activate the expression of downstream genes, such as CRL1, to induce callus formation. The significant loci and candidate genes identified here may provide insight into the mechanism underlying callus formation in rice.

The Impacts of Tumorigenic and Nontumorigenic Agrobacterium vitis Strains on Graft Strength and Growth of Grapevines.

The effects of tumorigenic and nontumorigenic strains of Agrobacterium vitis on graft strength and growth of grapevines was studied. A procedure was developed for inoculating graft interface surfaces with A. vitis and for measuring the force required to break grafts at different time points. Cuttings were soaked in an aqueous suspension of bacteria, about 106 CFU/ml, and bacteria were spread onto the graft interface during the grafting procedure. Tumorigenic strain CG49 caused reduced bud germination and increased callus (crown gall) at the graft union and at the base of cuttings at 30 days postinoculation (dpi) and significantly reduced shoot growth by 60 dpi whereas, at the same time points, nontumorigenic strain F2/5 inhibited callus formation but did not affect bud germination or shoot growth. Graft strength was enhanced at 30 dpi with CG49, presumably because the crown gall callus served to secure the union; graft strength was weakened by F2/5 over the same period. Between 30 and 60 dpi, the greatest increase in graft strength was observed in the water control. Following graft union inoculations, the A. vitis population increased more than 1,000-fold within 5 days.

In vitro cultivation of purple basil Ocimum basilicum L. ‘red rubin’ at different levels of salts, charcoal, sucrose and potassium iodine

Ocimum basilicum'red rubin' is highly valued for its essential oil, and is widely used in folk medicine, but few studies examining in vitro propagation techniques for this basil variety are available. We examined the development of red rubin basil seedlings grown in vitro in different concentrations of mineral salts, charcoal combined with sucrose, and potassium iodine in three series of tests. In the first series, five concentrations (0, 25, 50, 75 and 100%) of Murashige and Skoog salts (MS culture medium) were used to germinate sterilized seeds of O. basilicum. In the second test, to evaluate the combined effects of charcoal and sucrose on basil growth, three concentrations of charcoal (0, 3.0, and 4.5 g/L) and two of sucrose (30 and 60 g/L) were used. In the third test, the seeds were sown onto culture medium enriched with five different concentrations of potassium iodine (0, 25, 50, 75 and 100 M); 0.5 M benzyl aminopurine (BAP) and 1.0 M naphthalene acetic acid (NAA) were added to all germination media. A completely randomized experimental design was used in all tests, with five replicates, four vials per test, and 4 seeds per vial. In Test 2, seedling oxidation (%) and the numbers of leaves and shoots were submitted to non-parametric analysis using the Kruskal Wallis test (p =0.05). The other data were submitted to analysis of variance (p=0.05). The qualitative means were evaluated by the Tukey test (p=0.05), and the quantitative means by polynomial regression (p=0.05). The results showed that 100% MS culture medium was most indicated for 'red rubin' seed germination and aerial portion production, while 70-80% MS was indicated for root production. A sucrose level of 30 g/L (standard) combined with 4.5 g/L of activated charcoal allowed the best seedlings development and inhibited callus formation. Activated charcoal limited copper and zinc uptake by O. basilicum seedlings, but not enough to hamper their development. Increasing concentrations of potassium iodine reduced all of the growth variables analyzed in this basil variety.

Stress fracture in athletes

Stress fractures are widely encountered in sport medicine and rheumatology. Stress fractures result from abnormal and repetitive loading on normal bone that lead to microdamage and then fracture. They occur after sudden increase in physical activity. They appear mostly at lower limbs. Women are at higher risk than men. Patients complain of mechanical pain. Clinical findings include focused pain and sometimes swelling. No biological test is useful for diagnosis. Plain radiographs are normal in early stage disease. MRI is the gold standard to confirm stress fracture. Treatments of stress fracture always involve rest and analgesics. Non-steroidal anti-inflammatory should be use cautiously because they may inhibit callus formation. Extracorporeal shockwave may be a new approach for SF not healing with rest. Surgical treatment is often needed in high risk stress fracture of delayed healing, non-union or complete fracture.

Agrobacterium-mediated genetic transformation of Populus deltoides marsh clone G48 with gus and npt-II genes

Agrobacterium-Mediated Genetic Transformation of Populus deltoides Marsh Clone G48 with gus and npt-II Genes The present investigation had been carried out to standardize a protocol for Agrobacterium- mediated gene transfer in Populus deltoides Marsh. Clone G48 using petiole explants. Reproducibility of already standardized regeneration protocol for clone G48 had been evaluated. High frequency shoot regeneration (72%) from petiole explants was obtained on MS medium supplemented with 0.5 mg l-1 BAP, 0.2 mg l-1 IAA and 15 mg l-1 adenine sulphate. Root regeneration (100%) in in vitro developed shoots was obtained on MS medium supplemented with 0.1 mg l-1 IAA. Increasing concentrations of kanamycin (10-50 mg l-1) were given to find out the minimum dose of kanamycin required for the selection of putative transformed cells during genetic transformation. It was observed that a doze of 50 mg l-1 kanamycin inhibited callus formation and shoot regeneration and the explants turned brown and started dieing. This concentration of kanamycin would be the most useful for selection of npt-II gene transformed petiole cells/ tissues. Disarmed Agrobacterium tumefaciens LBA 4404 strain containing a reporter β-glucuronidase (gus) gene in binary vector pBI 121 along with kanamycin resistance gene (npt-II) was used for genetic transformation experiments. Only the transformed cells/ shoots were able to grow on selective shoot regeneration medium containing 50 mg l-1 kanamycin, whereas control explants did not survive. Regenerated putative transgenic shoots were subjected to transient gene expression analysis using spectrophotometric GUS assay and were found positive. This genetic transformation protocol will provide a platform for genetic manipulation of P. deltoides clone G48 for incorporation of genes governing various silviculturally important traits in future....

Establishment of plant regeneration system in Erianthus arundinaceus (Retz.) Jeswiet, a potential biomass crop

Erianthus arundinaceus (Retz.) Jeswiet is regarded as one of the most promising biomass crops because of its high-yield biomass and resistance to biotic and abiotic stresses. We investigated the frequencies of callus formation from seeds and leaf sheaths of E. arundinaceus under 25 culture conditions containing various concentrations and combinations of 2,4-dichlorophenoxyacetic acid (2,4-D) and 6-benzyladenine (BA). Callus formation from seeds was significantly affected by 2,4-D but not by BA. BA markedly inhibited callus formation from leaf sheaths, indicating that the pattern of the callus formation frequency in the tested media differed depending on the explant types. We showed that media containing 4.0 or 6.0 mg L−1 2,4-D effectively produced callus from both explants; medium containing 2.0 mg L−1 2,4-D was shown to be preferred for callus maintenance among the five tested subculture media. Plants were successfully regenerated on a hormone-free Murashige and Skoog medium, subsequently acclimatized and transplanted to an experimental field. To evaluate the genetic variability of the regenerated plants, random amplified polymorphic DNA (RAPD) analysis was performed in 31 regenerated plants with 17 primers. The result showed very few genetic changes among the regenerated plants in RAPD analysis. The present study demonstrated the establishment of the callus induction and plant regeneration system using seeds and leaf sheaths in E. arundinaceus, which contributed to the development of genetic engineering techniques for crop improvement.

Quantitative Screening of Engineered Implants in a Long Bone Defect Model in Rabbits

We have standardized a long bone defect model in rabbits to quantitatively compare the bone healing performance of engineered biological implants and have tested the bone healing efficiency of porous cylindrical scaffolds (ø-h, 6-20 mm [diameter 6 mm, height 20 mm] porosity, 70%) that were produced from hydroxyapatite (HA), titanium (Ti), and a novel biodegradable polymer-bioceramic composite (PH70alphaTCP). Scaffolds were perfused with or without 20 x 10(6) rabbit periosteal cells (RPCs) in a bioreactor and implanted in a standardized 2 cm defect in rabbit tibiae. X-rays revealed that new bone had formed at 3 weeks after creation of the defects. At sacrifice after 10 weeks, bone corticalization was observed in the majority of animals. Although PH70alphaTCP scaffolds did not inhibit callus formation, histomorphometric analysis revealed that there was no bone within the biomaterial, in contrast to HA and Ti scaffolds (bone volume ranging from 10% to 25%). We found that Ti and HA scaffold had good osteoconductive properties, but only HA scaffolds seeded with RPCs contributed to long bone mechanical functionality, with the maximum energy and angle being 308% and 155% greater than in control defects without scaffold.

Influence of endogenous IAA levels and exogenous IBA on rooting and quality of leafy cuttings of Prunus ‘GiSelA 5’

SummaryThe influence of exogenously applied indole-3-butyric acid (IBA) on root and shoot development of leafy cuttings was analysed in Prunus cerasus P. canescens ‘GiSelA 5’, a dwarfing cherry rootstock, in two successive years. Compared to control cuttings, IBA application (4 g l–1 in 2003; 2.5 g l–1 in 2004) caused higher indole-3-acetic acid (IAA) accumulation in the cutting bases, but that did not influence the percentage of rooted cuttings, nor their survival in either year. However, IBA inhibited callus formation and, consequently, influenced the quality of the developed cuttings. Callus formation impeded root development, reducing the number of main roots, and inhibited the growth of the cuttings, reducing the average total length of shoots formed by individual cuttings. Callus formation was most reduced in the cuttings in the second experimental year, with high initial IAA concentrations.

Indomethacin inhibition of ossification induced by direct current stimulation

In this study, we sought to clarify the mechanism of ossification induced by direct current stimulation by analyzing changes in local blood flow and vascular permeability and by examining the involvement of chemical mediators. Changes in blood flow were studied with laser Doppler flowmetry, and vascular permeability was determined by microquantification. To examine the involvement of chemical mediators, we determined the effect on vascular permeability of histamine H1 and H2-receptor blockers and indomethacin. In addition, direct current stimulation was performed during administration of indomethacin to determine whether indomethacin inhibits electrically induced callus formation. Local blood flow remained unchanged in the control group and in the group receiving 5 microA of stimulation, but it increased in the groups receiving 10 and 50 microA. Vascular permeability increased in the 5 and 10 microA stimulation groups. This increase was not suppressed by histamine-receptor blockers, but it was suppressed by indomethacin. Two weeks of electrical stimulation without concomitant indomethacin treatment resulted in active callus formation around the needle electrode and in the vicinity of the endosteum; however, direct current stimulation during administration of indomethacin inhibited callus formation. The results suggest that these changes serve as microenvironmental factors that play an important role in the promotion of ossification and that a prostaglandin-mediated mechanism is involved in the promotion of ossification by direct current stimulation.

Somatic Embryogenesis and Plant Regeneration in Cucumber

The embryogenic capacity of seven cucumber (Cucumis sativus L.) cultivars was examined by tissue culture of cotyledon, young first-leaf, and internode explants. Somatic embryogenesis frequencies differed significantly among the tested cultivars, and `Fushinarimidori' produced the highest number of embryos from either cotyledons or young first leaves. Cotyledon- and first-leaf-derived calluses produced more embryos than calluses from internodes. Somatic embryos were induced from `Aonaga F1' internodes. With relatively high sucrose levels (6% and 9%) in the initiation medium, the frequency of embryogenic callus formation from `Fushinarimidori' cotyledon explants was >90%. The highest yield of somatic embryos occurred in cultures initiated with high sucrose levels (9% or 12%), although 12% sucrose inhibited callus formation and growth. Somatic embryos germinated in a basal liquid medium supplemented with 0.5% activated charcoal, and they developed into well-shaped, healthy plantlets on semisolid medium with 1% sucrose.

REGENERATION OF CHINESE JUJUBE(ZIZYPHUS JUJUBA MILLER) FROM IMMATURE COTYLEDONS AND SEGMENTS OF SEEDLING

Immature cotyledons within nucleoulus of young fruits, 40-50 days old, were cultured on various media containing different concentrations of plant growth regulators. MS medium was most effective for callus formation, but cytokinins added to MS media containing 1.0 mg/l 2,4-D inhibited callus formation. Combination of 2,4-D and BAP was more effective than 2,4-D or BAP alone for somatic embryo formation from callus. Highest percent of somatic embryogenesis was observed on MS medium supplemented with 1.0mg/l 2,4-D and 50% sucrose. Cobalt and nickel, inhibitors of ethylene synthesis, reduced significantly the number of somatic embryos. Plantlets germinated freely from somatic embryos on MS medium containing 1.0mg/l zeatin and 0.01mg/1 2,4-D. Segments of hypocotyl, cotyledon and leaf blade were observed for callus formation, somatic enbryogenesis and plant regeneration. Shoots were directly differentiated from the callus induced from segments of hypocotyl on MS medium containing 0.1mg/l 2,4-D after 4 weeks of culture.

Identification of somatic hybrids in plant protoplast fusions with monoclonal antibodies to plasma-membrane antigens

Monoclonal antibodies generated by immunization with a plasma-membrane preparation from suspension-cultured cells of Nicotiana glutinosa L. were used in combination with fluoresceinor rhodamine-labeled goat anti-mouse immunoglobulins to identify heterokaryons in protoplast fusion procedures. Antibody labeling did not inhibit callus formation nor plantlet regeneration. The antibodies are non-invasive and surface labeling provides clear optical discrimination of true heterokaryons from unfused aggregates as well as from parental protoplasts and homokaryons. Labeling is stable throughout fusion and hence by pre-labeling parental protoplast populations the strategy is both versatile and of general applicability.

The Physical Environment in Relation to High Frequency Callus and Plantlet Development in Anther Cultures of Wheat ( Triticum aestivum L.) cv. Chris

Summary Several physical treatments have been examined for their effects upon callus formation and plant regeneration in anther cultures of the spring wheat ( Triticum aestivum L. em. Thell) cultivar «Chris». Variation in intensity and duration of low-temperature treatment was found to result in significant differences in callus formation frequency. Also, the use of a semi-solid support medium significantly inhibited callus formation relative to liquid medium, when the optimum cold treatment was used. No significant differences existed among the above treatments for ultimate plantlet production frequencies. Optimal treatments, namely, 2 week treatment of cut tillers at 4 °C in darkness, followed by culture on liquid medium, resulted in callus formation from over 14% of anthers plated and plantlet formation from over 40% of these calli.

Fracture Healing in Metastatic Bone Disease

In 123 cancer patients with metastatic disease, 129 pathologic fractures of long bones were assessed to determine the rate of osseous union. Bony healing was observed in 67% of malignant fractures from multiple myeloma, in 44% of fractures secondary to metastatic hypernephroma, and in 37% of neoplastic fractures from breast carcinoma. No patient with a pathologic fracture secondary to lung carcinoma demonstrated bony repair, and none of these patients lived for more than six months after fracture. The overall fracture healing rate for the entire study population was 35%. In the group that survived longer than six months, 74% of fractures united. A life expectancy of longer than six months was the primary factor determining osseous healing in all patients. A total radiotherapy dose of 3000 rad or less did not inhibit callus formation. Internal fixation improved the rate of fracture union by 23% as compared with cast immobilization.