Broiler litter ammonia emissions near sidewalls, feeders, and waterers.

Ammonia (NH3) volatilized from broiler litter diminishes indoor air quality, which can potentially decrease bird productivity. Emissions of NH3 exhausted from broiler houses pose environmental concerns for ecosystem biodiversity, aquatic nutrient enrichment, and particulate formation in the atmosphere. Research was conducted sampling litter (rice hull base) in 3 tunnel-ventilated commercial broiler houses during wk 3 (mid-growout) of 6 flocks. The purpose was to assess NH3 generated near the sidewalls, waterers, and feeders. Litter samples (100 g) were placed in chambers receiving constant air flow. Boric acid (H3BO3) titration each 24 h for 4 d was used to determine NH3 volatilized from the samples. Litter located near waterers emitted the most cumulative NH3 (approximately 12.3 mg of N•kg of litter(-1)•h(-1)) with less NH3 associated with feeders and sidewalls (2.9 to 7.6 mg of N•kg of litter(-1)•h(-1)). Moisture content of litter samples was greatest at waterers (45%) followed by sidewalls (26%) and feeders (20%). In addition, litter pH at the sidewalls and feeders could be predicted by linear equations associated with the number of flocks on the litter. At the waterers, litter pH was differentiated based on the half of house where higher litter pH existed in the nonbrood half (8.55 vs. 8.13). The results indicate that controlling NH3 near watering lines to a level consistent with feeding lines and near the house wall could reduce NH3 generated by 38 to 77%. These findings support efforts for NH3 control at mid-growout, especially considering zone litter treatments near waterers and appropriate attention to waterer management.

High litter moisture content suppresses litter ammonia volatilization.

With global food demand expected to increase by 100% in the next 50 yr, urgency to combine comprehensive strategies for sustainable, efficacious, and environmentally sensible agronomic practices has never been greater. One effort for US meat bird management is to reduce NH(3) volatilization from litter to create a better growing environment for the birds, improve production efficiency, retain N in litter for fertilizer value, and negate the detrimental environmental impacts of NH(3) loss to the air. To derive the fundamental effects of temperature and moisture on litter NH(3) volatilization over the range of conditions found in commercial houses, experiments were conducted using commercial broiler litter that had moisture contents of approximately 20 to 55% while controlling temperatures ranging from 18.3 to 40.6°C. Litter samples (100 g) were placed in 1-L containers that received humidified air at approximately 113 mL/min. Volatilized NH(3) in exhaust air was captured in H(3)BO(3) traps. Ammonia loss (log(10) transformation) was modeled via an equation using linear coefficients for temperature and moisture, an interaction term for temperature × moisture, and a quadratic term for moisture. The surface responses resembled parabolic cylinders, indicating a critical moisture level at which NH(3) no longer increases but is diminished as moisture continues to increase. The critical moisture level lies between 37.4 and 51.1% litter moisture, depending on the temperature. An increase in temperature consistently increased NH(3) generation. When the temperature extremes were compared, the maximum NH(3) was up to 7 times greater at 40.6 vs. 18.3°C. The upper moisture limit at which NH(3) release is maximized and subsequently arrested as moisture continues to increase had not been defined previously for commercial broiler litter. The poultry industry and researchers can use these results as a decision tool to enable management strategies that limit NH(3) production.

Litter ammonia generation: moisture content and organic versus inorganic bedding materials.

Negative impacts on the environment, bird well-being, and farm worker health indicate the need for abatement strategies for poultry litter NH(3) generation. Type of bedding affects many parameters related to poultry production including NH(3) losses. In a randomized complete block design, 3 trials compared the cumulative NH(3) volatilization for laboratory-prepared litter (4 bedding types mixed with excreta) and commercial litter (sampled from a broiler house during the second flock on reused pine wood chips). Litters were assessed at the original moisture content and 2 higher moisture contents. Broiler excrement was mixed with pine wood shavings, rice hulls, sand, and vermiculite to create litter samples. Volumetrically uniform litter samples were placed in chambers receiving humidified air where the exhaust passed through H(3)BO(3) solution, trapping litter-emitted NH(3). At the original moisture content, sand and vermiculite litters generated the most NH(3) (5.3 and 9.1 mg of N, respectively) whereas wood shavings, commercial, and rice hull litters emitted the least NH(3) (0.9-2.6 mg of N). For reducing NH(3) emissions, the results support recommendations for using wood shavings and rice hulls, already popular bedding choices in the United States and worldwide. In this research, the organic bedding materials generated the least NH(3) at the original moisture content when compared with the inorganic materials. For each bedding type, incremental increases in litter moisture content increased NH(3) volatilization. However, the effects of bedding material on NH(3) volatilization at the increased moisture levels were not clearly differentiated across the treatments. Vermiculite generated the most NH(3) (26.3 mg of N) at the highest moisture content. Vermiculite was a novel bedding choice that has a high water absorption capacity, but because of high NH(3) generation, it is not recommended for further study as broiler bedding material. Controlling unnecessary moisture inputs to broiler litter is a key to controlling NH(3) emissions.

Effects of commercial in ovo injection of carbohydrates on broiler embryogenesis.

The effects of in ovo injection of different carbohydrate solutions on hatchability of fertilized eggs (HF), rate of hatch, BW, body moisture, yolk sac weight, and yolk sac moisture of Ross × 708 broiler chicks, hatched from eggs laid by a 34-wk-old breeder flock, were investigated. Eggs containing live embryos were injected, using an automated multiple-egg injector, in the amnion on d 18.5 of incubation with 0.1, 0.4, 0.7, or 1.0 mL of commercial diluent or a carbohydrate dissolved in diluent. The commercial diluent containing 0.25 g/mL of one of the following carbohydrates was injected into eggs: glucose, fructose, sucrose, maltose, or dextrin. The results showed that no carbohydrate type or solution volume affected rate of hatch. Absolute and proportional BW on day of hatch were positively related to injection volume (P < 0.001). However, HF was negatively related to injection volume (P < 0.001). To realize an HF of 90%, the injection volume could not exceed 0.4 mL for fructose or sucrose and could not exceed 0.7 mL for glucose, maltose, or dextrin. Yolk-free BW was negatively related to injection volume of fructose and sucrose (P < 0.004), but was not related to injection volume of diluent, glucose, maltose, and dextrin. Conversely, absolute and proportional yolk sac weights were positively related to injection volume of fructose, sucrose, and dextrin (P < 0.01), but were also not significantly related to injection volume of diluent, glucose, and maltose. Yolk sac moisture was positively related to injection volume for all injectables, including the diluent (P < 0.03). However, body moisture and yolk-free body moisture were not related to injection type or volume. In conclusion, the use of carbohydrates added to a commercial diluent for the in ovo injection of broiler hatching eggs requires the use of appropriate volumes to promote growth and nutrient utilization without adversely affecting HF.

Effect of surface incorporation of broiler litter applied to no-till cotton on runoff quality.

Surface application of broiler litter to no-till cotton could lead to degradation of water quality. Incorporation of broiler litter into the top surface soil (0.05 m) could alleviate this risk. A 2-yr field study was conducted on a silt loam upland soil to determine the effect of incorporation of broiler litter into the soil surface on nutrient and bacterial transport in runoff. The experimental design was a randomized complete block with four treatments and three replications. Treatments were (i) unfertilized control; (ii) surface-appliedbroiler litter at 7.8 Mg ha(-1) without incorporation; (iii) surface-applied broiler litter at 7.8 Mg ha(-1) with immediate incorporation; and (iv) inorganic fertilizer N (urea ammonium nitrate, 32% N) and inorganic fertilizer P (triple superphosphate) at the recommended rate. Phosphorus was surface appliedat 25 kg ha(-1) and N was injected at 101 kg ha(-1) into the soil using a commercial liquid fertilizer applicator. Runoff was collected from small runoff plots (2.4 m by 1.6 m) established at the bottom side of main plots (13.7 m by 6.0 m). Incorporation of broiler litter reduced total N (TN), NO3-N, water soluble P (WSP), and total P (TP) concentrations in runoffby 35, 25, 61, and 64%, respectively, and litter-associated bacteria by two to three orders of magnitude compared with unincorporated treatment. No significant difference in total suspended solids (TSS) in runoffwas obtained between incorporated and unincorporated treatments. Incorporation of broiler litter into the surface soil in the no-till system immediately after application minimized the potential risk for surface nutrient losses and bacteria transport in runoff.

Spatial variability of litter gaseous flux within a commercial broiler house: ammonia, nitrous oxide, carbon dioxide, and methane.

Twenty-eight flocks were grown on litter in a tunnel-ventilated, curtain-sided commercial broiler house prior to this summer flock. Grid measurements were made using a photo-acoustic multigas analyzer to assess the spatial variability of litter gases (NH3, N2O, CO2, and CH4) on d 1 and 21. The pooled results for the brood and non-brood areas of the house were 1) NH3 flux was greatest in the brood area at d 1, averaging 497 mg/(m2 x h), and had a mean of 370 mg/(m2 x h) in the vacant end of the house; 2) at d 21, the non-brood area had the greater average NH3 flux, 310 mg/(m2 x h), and flux in the brood area was 136 mg/(m2 x h); 3) N2O and CH4 fluxes were <60 mg/(m2 x h); and 4) on d 1, brood CO2 flux was 6,190 mg/(m2 x h) compared with 5,490 mg/ (m2 x h) at the opposite end of the house. On d 21, these values increased to 6,540 and 9,684 mg/(m2 x h) for the brood and non-brood areas. Ammonia flux seemed most affected by litter temperature. Carbon dioxide and CH4 increased from placement to mid growout, corresponding to increased moisture, especially near the fans. Contour plots were developed using geostatistical software to visually assess the spatial disparity among the measurements. This research provides a unique view of gas flux variation within the house. Collinear factors such as house management, bird size and age, and amount of deposition are significant factors for litter gas flux and should be considered in comprehensive models for emission estimates.

Broiler litter as a micronutrient source for cotton: concentrations in plant parts.

Analytically, poultry litter contains nearly all essential micronutrients but the extent of phytoavailability of these nutrients and whether cotton (Gossypium hirsutum L.) and other crop plants can receive adequate amounts of these nutrients from litter is not fully known. The objective of this research was to determine whether cotton receives sufficient amounts of Fe, Cu, Mn, and Zn from litter and estimate the efficiency of cotton in extracting these metal nutrients from litter in the absence of any other source of the micronutrients. The greenhouse research used plastic pots filled with approximately 11 kg of a 2:1 (v/v) sand to vermiculite growing mix. Cotton (cv. Stoneville 474) was grown in the pots fertilized with broiler litter at rates of 30, 60, 90, or 120 g pot(-1) in a factorial combination with four supplemental nutrient solution (NS) treatments. The nutrient solutions consisted of full Hoagland's nutrient solution (NS-full); a solution of the macronutrients N, P, K, Ca, and Mg (NS-macro); a solution of the micronutrients Fe, Zn, Mn, Cu, B, and Mo (NS-micro); and water (NS-none). Based on tissue nutrient analysis, a one-time broiler litter application supplied adequate amounts of Fe, Cu, and Mn to bring the concentration of these nutrients in upper leaves within published sufficiency ranges. Zinc, with <17 mg kg(-1) concentration in the upper leaves, was the only micronutrient below the established sufficiency range regardless of the rate of applied litter. Cotton extracted Fe and Mn more efficiently than Cu or Zn, removing as much as 8.8% of Fe and 7.2% of Mn supplied by 30 g litter pot(-1). In contrast, the extraction efficiency was 1.7% for Cu and 1.9% for Zn. Roots accumulated 58% of the total absorbed Fe and 64% of Cu, and leaves accumulated 32% of the Fe and only 13% of the Cu supplied by litter. In contrast, only 16% of the total absorbed Mn and 23% of Zn accumulated in roots while leaves accumulated 64% of the total Mn and 37% of Zn. These results demonstrate that broiler litter is a valuable source of the metal nutrients supplying Fe, Cu, and Mn in full and Zn in part, but a very large fraction of the litter-supplied metal nutrients remained in the growing mix.

Characterization of broiler cake and broiler litter, the by-products of two management practices.

The application of broiler manure and bedding (litter) on land has been a long-used disposal method that benefits plant and soil. For proper manure management, factors such as nutrient content, house cleaning management, application methods, and many land, crop, and climatic factors must be considered. A study was undertaken to characterize broiler cake and broiler litter as the by-products of two management systems in Mississippi. Broiler cake and litter productions were quantified and analyzed for four flocks during 1999 and 2000. The overall means for broiler cake production were 12.50, 13.90, and 10.30 kg m(-2) for producers 1, 2, and 3, respectively. Significantly greater quantities of litter, 27.50, 29.0, and 28.30 kg m(-2) than cake were determined for the same producers. The cake and litter moisture averaged 455 and 277 g kg(-1), respectively. No significant differences were observed between cake and litter total N, NH4-N, total C, total P, and water-soluble P (WP). However, cake had significantly greater Ca, Mg, K, Cu, Fe, Mn, and Zn than litter. Approximately 16.8% of the broiler cake and 15.2% of the broiler litter total P were in the form of water-soluble P. The NH4-N content of the cake and the litter were 12.5% and 11.5% of the cake and litter total nitrogen, respectively. The results also showed the advantage of the decaking practice with respect to the quantity of the manure generated for land application. Approximately 57% of the litter remains in the poultry house with decaking practice after each growth cycle compared to the 0% for total cleanout practice.

Swine effluent irrigation rate and timing effects on bermudagrass growth, nitrogen and phosphorus utilization, and residual soil nitrogen.

Maximizing utilization of effluent nutrients by forage grasses requires a better understanding of irrigation rate and timing effects. This study was conducted in 1998 and 1999 on a Vaiden silty clay (very-fine, smectitic, thermic Aquic Dystrudert) soil to determine the effects of swine lagoon effluent irrigation rate and timing on bermudagrass [Cynodon dactylon (L.) Pers.] growth, nitrogen (N) and phosphorus (P) recovery, and postseason soil profile NO3(-)-N. Treatments consisted of swine effluent irrigation at the rates of 0, 5, 10, 15, and 20 ha-cm. Two additional treatments included 2.5 ha-cm applied on 1 September and 1 October in addition to a base summer rate of 10 ha-cm. In both years for early to mid-season irrigation, bermudagrass dry matter yield quadratically increased with increasing swine effluent irrigation rates. Averaged across years, effluent irrigation in October resulted in 30% less dry matter than in September. For late-season irrigation, apparent N recovery averaged 59% less and P recovery averaged 46% less with a delay in irrigation from 1 September to 1 October. The greatest quantity of soil NO3(-)-N was associated with both the greatest effluent rate and October irrigation treatments. Minimal yield benefit was obtained when effluent was applied at rates greater than 10 ha-cm during the summer months. Late-season irrigation, especially after 1 October for areas with similar climatic conditions, should be avoided to maximize synchronization of nutrient availability with maximum growth rates to minimize potential offsite movement of residual soil N and P.

Enhanced Resistance to Sclerotium rolfsii in Populations of Alfalfa Selected for Quantitative Resistance to Sclerotinia trifoliorum.

ABSTRACT Sclerotinia trifoliorum and Sclerotium rolfsii are pathogens for which similar mechanisms of parasitism have been proposed. This suggested that resistance to these pathogens may be related in a common host plant. This study was undertaken to determine whether selection for quantitative resistance to Sclerotinia trifoliorum in alfalfa also increases resistance to Sclerotium rolfsii as expressed in excised leaf tissues and whole plants. Resistance in excised leaf tissues was evaluated according to the rate of necrosis induced by Sclerotium rolfsii following inoculation with mycelium. Resistance to Sclerotium rolfsii in whole plants was evaluated according to their survival following crown inoculations. Three alfalfa populations previously selected from cv. Delta for quantitative resistance to Sclerotinia trifoliorum exhibited enhanced resistance to Sclerotium rolfsii, in comparison with Delta or with susceptible populations, in excised leaf tissues. When whole plants of Delta and two of these populations, Sclerotinia trifoliorum resistant (STR) and Mississippi Sclerotinia resistant (MSR), were inoculated with Sclerotium rolfsii at 3 to 8 weeks of age, significant (P = 0.01) differences in survival were attributed to plant age at inoculation and alfalfa populations. Survival of both MSR and STR was significantly (P = 0.05) greater than for Delta; the best differential results were obtained by inoculating plants 5 to 7 weeks old. To evaluate relationships of resistance to Sclerotinia trifoliorum and Sclerotium rolfsii over a broader genetic background, additional populations were selected for resistance to Sclerotinia trifoliorum from four other alfalfa cultivars by leaf-inoculation techniques, and this resistance was confirmed by whole-plant inoculations. In excised leaf tissues, all four of these populations also expressed enhanced resistance to Sclerotium rolfsii in comparison with either parent cultivars or populations of comparable size selected at random. These results establish that selection for quantitative resistance to Sclerotinia trifoliorum in alfalfa also confers enhanced resistance to Sclerotium rolfsii as expressed in excised leaf tissues and whole plants. Results suggest, therefore, that genes for quantitative resistance to Sclerotinia trifoliorum and Sclerotium rolfsii in alfalfa are likely to be synonymous, overlapping, or closely linked.

Diffuse idiopathic skeletal hyperostosis: musculoskeletal manifestations.

Diffuse idiopathic skeletal hyperostosis (DISH) is a common disorder of unknown etiology that is characterized by back pain and spinal stiffness. There may be mild pain if ankylosis has occurred. The condition is recognized radiographically by the presence of "flowing" ossification along the anterolateral margins of at least four contiguous vertebrae and the absence of changes of spondyloarthropathy or degenerative spondylosis. Even in patients who present with either lumbar or cervical complaints, radiographic findings are almost universally seen on the right side of the thoracic spine. Thus, radiographic examination of this area is critical when attempting to establish a diagnosis of DISH. The potential sequelae of hyperostosis in the cervical and lumbar spine include lumbar stenosis, dysphagia, cervical myelopathy, and dense spinal cord injury resulting from even minor trauma. There may be a delay in diagnosis of spinal fractures in a patient with DISH because the patient often has a baseline level of spinal pain and because the injury may be relatively trivial. The incidence of delayed neurologic injury due to such fractures is high as a result of unrecognized instability and subsequent deterioration. Extraspinal manifestations are also numerous and include an increased risk of heterotopic ossification after total hip arthroplasty. Prophylaxis to prevent heterotopic ossification may be indicated for these patients.

Evaluation of Simplified Leaf Inoculation Procedures for Identification of Quantitative Resistance to Sclerotinia trifoliorum in Alfalfa Seedlings.

Previous studies established that excised leaf tissues of alfalfa can be inoculated with Sclerotinia trifoliorum to select for heritable resistance, but the original procedures were not practical for use in large-scale screening programs. In this study, simplified leaf inoculation procedures for more rapid screening for resistance, based on direct application of leaf tissues to colonies of the pathogen on agar media, were evaluated. Cotyledons, unifoliate leaves, and leaflets of trifoliolate leaves of plants 7 to 21 days old from three relatively susceptible cultivars and one resistant germ plasm were applied, with and without wounding, directly to colony margins of S. trifoliorum on cornmeal agar, V8 juice agar, and water agar. Leaves were scored according to the rate and extent of development of necrosis. Significant differences between alfalfa populations were expressed in unifoliate leaves and trifoliolate leaflets but not in cotyledons. Disease severity in the resistant germ plasm (Mississippi Sclerotinia-Resistant [MSR]) was less than in the three cultivars on all agar media. Wounding of leaf tissues increased disease severity and greatly reduced the incidence of symptomless leaves, which are indicated to be escapes, but wounding generally did not prevent expression of resistance in MSR. Results indicate that initial screening for resistance to S. trifoliorum in alfalfa seedlings may be accomplished by applying wounded unifoliate leaves and leaflets of trifoliolate leaves directly to colonies on cornmeal or V8 juice agars.

Pathogenicity of Macrophomina phaseolina to Mature Plant Tissues of Alfalfa and White Clover.

Macrophomina phaseolina has been observed on alfalfa and white clover in North America, but its pathogenicity to mature plants of these species has not been adequately documented and Koch's postulates have not been fulfilled. Isolates of M. phaseolina from alfalfa and white clover were evaluated for pathogenicity by inoculating tissues of mature plants with infested toothpick pieces. Excised leaf tissues also were inoculated with mycelium. In stolons of white clover and stems of alfalfa, M. phaseolina caused a brown-black, basipetally progressive necrosis of vascular tissue with subsequent collapse of the surrounding pith and epidermis to produce radially constricted, expanding lesions. In taproots and crowns of alfalfa, M. phaseolina caused dark discoloration of vascular tissues in bands or streaks above and below inoculation points with subsequent invasion and death of cortical tissues, lateral roots, and stems. Sclerotia formed in all tissues of both species. Excised leaf tissues were rapidly parasitized, but significant differences in rates of parasitism between genotypes suggested that differences in host resistance to M. phaseolina may be present in both species. Pycnidia formed on leaves of bean, lima bean, and cotton. All isolates of M. phaseolina were reisolated from margins of necrosis in all types of inoculated tissues and regrown in pure culture. These results fulfill Koch's postulates for M. phaseolina as a pathogen of mature white clover and alfalfa in North America, and they demonstrate its capacity to parasitize a variety of tissues of both species in the absence of other pathogens. Results indicate that M. phaseolina should be considered a potential cause for lack of persistence of white clover and alfalfa during summer months in the southeastern United States.

A meta-analysis of the efficacy of non-operative treatments for idiopathic scoliosis.

With use of data culled from twenty studies, members of the Prevalence and Natural History Committee of the Scoliosis Research Society conducted a meta-analysis of 1910 patients who had been managed with bracing (1459 patients), lateral electrical surface stimulation (322 patients), or observation (129 patients) because of idiopathic scoliosis. Three variables - the type of treatment, the level of maturity, and the criterion for failure - were analyzed to determine which had the greatest impact on the outcome. We also examined the effect of the type of brace that was used and the duration of bracing on the success of treatment. The number of failures of treatment in each study was determined by calculating the total number of patients who had unacceptable progression of the curve (as defined in the study), who could not comply with or tolerate treatment, or who had an operation. The percentage of patients who completed a given course of treatment without failure, adjusted for the sample sizes of the studies in which that treatment was used, yielded the weighted mean proportion of success for that treatment. The weighted mean proportion of success was 0.39 for lateral electrical surface stimulation, 0.49 for observation only, 0.60 for bracing for eight hours per day, 0.62 for bracing for sixteen hours per day, and 0.93 for bracing for twenty-three hours per day. The twenty-three-hour regimens were significantly more successful than any other treatment (p < 0.0001). The difference between the eight and sixteen-hour regimens was not significant, with the numbers available. Although lateral electrical surface stimulation was associated with a lower weighted mean proportion of success than observation only, the difference was not significant, with the numbers available. This meta-analysis demonstrates the effectiveness of bracing for the treatment of idiopathic scoliosis. The weighted mean proportion of success for the six types of braces included in this review was 0.92, with the highest proportion (0.99) achieved with the Milwaukee brace. We found that use of the Milwaukee brace or another thoracolumbosacral orthosis for twenty-three hours per day effectively halted progression of the curve. Bracing for eight or sixteen hours per day was found to be significantly less effective than bracing for twenty-three hours per day (p < 0.0001).

Complications associated with harvesting autogenous iliac bone graft.

The harvesting of an autogenous iliac bone graft is a frequently performed orthopedic procedure. Although often regarded as the simple or routine part of bone graft requiring surgery, complications are not necessarily uncommon. Documented donor-site complications include nerve, arterial, or urethral injury; chronic donor-site pain; cosmetic deformity; herniation of abdominal contents; sacroiliac joint instability; pelvic fractures; gait disturbances; hematoma; infection; peritoneal perforation; and hip subluxation. Most of these complications are avoidable when the surgeon is aware of their possibility and is familiar with the involved anatomy and preferred surgical approaches.

Pitfalls of pedicle screw fixation in the sacrum. A cadaver model.

Five male cadavers were used to evaluate anatomically structures at risk using sacral pedicle screw fixation. Risk was defined as the likelihood of penetration by K-wires placed through the pedicles and cortices at the S1, S2, and S3 levels. A scale based on the distance from the wire to the vital structure was developed to quantify risk. Instrument insertion techniques were classified as direct and lateral. The direct technique at S1 placed the left common iliac vein and the sympathetic chain at high risk. The sympathetic chain was also at high risk at the S2 and S3 levels. The lateral technique placed the lumbosacral trunk at high risk at the S1 level, as well as the S1 nerve root with screw placement at the S2 level. Anterior cortical penetration during sacral pedicle screw fixation places anatomic structures at variable risk depending on the technique used.

Prognostic factors for local recurrence, metastasis, and survival rates in squamous cell carcinoma of the skin, ear, and lip. Implications for treatment modality selection.

We reviewed all studies since 1940 on the prognosis of squamous cell carcinoma (SCC) of the skin and lip. The following variables are correlated with local recurrence and metastatic rates: (1) treatment modality, (2) prior treatment, (3) location, (4) size, (5) depth, (6) histologic differentiation, (7) histologic evidence of perineural involvement, (8) precipitating factors other than ultraviolet light, and (9) host immunosuppression. Local recurrences occur less frequently when SCC is treated by Mohs micrographic surgery. This local recurrence rate differential in favor of Mohs micrographic surgery holds true for primary SCC of the skin and lip (3.1% vs 10.9%), for ear SCC (5.3% vs 18.7%), for locally recurrent (previously treated) SCC (10% vs 23.3%), for SCC with perineural involvement (0% vs 47%), for SCC of size greater than 2 cm (25.2% vs 41.7%), and for SCC that is poorly differentiated (32.6% vs 53.6%).

Squamous cell carcinoma of the skin (excluding lip and oral mucosa).

The striking impression obtained from reviewing the cancer literature is how difficult it is to analyze the data for answers to many important biologic, behavioral, prognostic, and therapeutic questions about squamous cell carcinoma of the skin. This article addresses current concepts, controversies, and management of cutaneous squamous cell carcinoma (excluding the lip and oral mucosa).

The operative treatment of scoliosis in Duchenne muscular dystrophy.

The results of segmental spinal stabilization and fusion in nine patients with Duchenne muscular dystrophy are reviewed. The average follow-up time was 3.2 years. Vital capacities averaged 46% (range, 20% to 70%), and there were minimal pulmonary complications. Operative time and blood loss decreased when the spinal fixation method was changed from sublaminar to intraspinous wiring. Segmental wiring anchored through the spinous processes also maintained reduction and distraction until fusion occurred; we recommend this technique. The use of allogenic bone grafts to supplement the autogenous bone graft allowed for extensive fusion; we recommend this technique as well. Furthermore, fusion to the sacrum to prevent further pelvic obliquity should be indicated in all patients who develop scoliosis.