Monte Carlo Simulations as a Decision Support to Interpret δ15 N Values of Nitrate in Groundwater.

Intense farming is often associated with the excessive use of manure or fertilizers and the subsequent deterioration of the groundwater quality in many aquifers worldwide. Stable isotopes of dissolved nitrate (δ15 N and δ18 O) are widely used to determine sources of nitrate contamination and denitrification processes in groundwater but are often difficult to interpret. Thus, Monte Carlo simulations were carried out for a site in lower Bavaria, Germany, in order to explain δ15 N observations in a porous groundwater system with two aquifers, the main aquifer (MA) and several smaller perched aquifers (PA). For evaluating potential contributions, frequency distributions of δ15 N were simulated deriving from (I) the mixing of different nitrate sources, related to land use, as input to groundwater, combined with (II) transport of nitrate in groundwater and (III) microbial denitrification. Simulation results indicate a source-driven isotopic shift to heavier δ15 N values of nitrate in groundwater, which may be explained by land use changes toward a more intensified agriculture releasing high amounts of manure. Microbial denitrification may play a role in the PA, with simulated δ15 N distributions close to the observations. Denitrification processes are however unlikely for the MA, as reasonable simulation curve fits for such a scenario were obtained predominantly for unrealistic portions of nitrate sources and related land use. The applied approach can be used to qualitatively and quantitatively evaluate the influence of different potential contributions, which might mask each other due to overlapping δ15 N ranges, and it can support the estimation of nitrate input related to land use.

Effects of high-fat diets on fetal growth in rodents: a systematic review.

BACKGROUND: Maternal nutrition during pregnancy has life-long consequences for offspring. However, the effects of maternal overnutrition and/ or obesity on fetal growth remain poorly understood, e.g., it is not clear why birthweight is increased in some obese pregnancies but not in others. Maternal obesity is frequently studied using rodents on high-fat diets, but effects on fetal growth are inconsistent. The purpose of this review is to identify factors that contribute to reduced or increased fetal growth in rodent models of maternal overnutrition. METHODS: We searched Web of Science and screened 2173 abstracts and 328 full texts for studies that fed mice or rats diets providing ~ 45% or ~ 60% calories from fat for 3 weeks or more prior to pregnancy. We identified 36 papers matching the search criteria that reported birthweight or fetal weight. RESULTS: Studies that fed 45% fat diets to mice or 60% fat diets to rats generally did not show effects on fetal growth. Feeding a 45% fat diet to rats generally reduced birth and fetal weight. Feeding mice a 60% fat diet for 4-9 weeks prior to pregnancy tended to increase in fetal growth, whereas feeding this diet for a longer period tended to reduce fetal growth. CONCLUSIONS: The high-fat diets used most often with rodents do not closely match Western diets and frequently reduce fetal growth, which is not a typical feature of obese human pregnancies. Adoption of standard protocols that more accurately mimic effects on fetal growth observed in obese human pregnancies will improve translational impact in this field.

A prospective, randomized clinical trial comparing an antibiotic-impregnated bioabsorbable bone substitute with standard antibiotic-impregnated cement beads in the treatment of chronic osteomyelitis and infected nonunion.

OBJECTIVES: We sought to compare the effectiveness of an antibiotic-impregnated bioabsorbable bone substitute (BBS, tobramycin-impregnated medical-grade calcium sulfate) with antibiotic-impregnated polymethylmethacrylate (PMMA) cement beads after surgical débridement in patients with chronic nonhematogenous osteomyelitis and/or infected nonunion. DESIGN: A prospective, randomized clinical trial. SETTING: A university-affiliated teaching hospital. PATIENTS/PARTICIPANTS: Thirty patients requiring surgical treatment for chronic long bone infection or infected nonunion were included: BBS (15 patients, mean age 44.1 years) PMMA (15 patients, mean age 45.6 years). INTERVENTION: Patients were randomized to receive either BBS or PMMA to the bone void created by surgical débridement. MAIN OUTCOME MEASUREMENTS: Eradication of infection, new bone growth, rate of union, repeat operative procedures complications. RESULTS: Patients were followed for a mean 38 months (range, 24-60 months). One patient was lost to follow-up in each group. In the BBS group, infection was eradicated in 86% (12 of 14) of patients. Seven of eight patients achieved union of their nonunion, and five patients underwent seven further surgical procedures. In the PMMA group, infection was eradicated in 86% (12 of 14) of patients. Six of eight patients achieved union of their nonunion, and nine patients required 15 further surgical procedures. There were more reoperations in the PMMA group (15 versus seven, P = 0.04), and these procedures tended to be of greater magnitude. CONCLUSIONS: The results of this preliminary study suggest that, in the treatment of chronic osteomyelitis and infected nonunion, the use of an antibiotic-impregnated BBS is equivalent to standard surgical therapy in eradicating infection and that it may reduce the number of subsequent surgical procedures. A larger, definitive study on this topic is required.

A multicenter, prospective, randomized, controlled trial of open reduction--internal fixation versus total elbow arthroplasty for displaced intra-articular distal humeral fractures in elderly patients.

We conducted a prospective, randomized, controlled trial to compare functional outcomes, complications, and reoperation rates in elderly patients with displaced intra-articular, distal humeral fractures treated with open reduction-internal fixation (ORIF) or primary semiconstrained total elbow arthroplasty (TEA). Forty-two patients were randomized by sealed envelope. Inclusion criteria were age greater than 65 years; displaced, comminuted, intra-articular fractures of the distal humerus (Orthopaedic Trauma Association type 13C); and closed or Gustilo grade I open fractures treated within 12 hours of injury. Both ORIF and TEA were performed following a standardized protocol. The Mayo Elbow Performance Score (MEPS) and Disabilities of the Arm, Shoulder and Hand (DASH) score were determined at 6 weeks, 3 months, 6 months, 12 months, and 2 years. Complication type, duration, management, and treatment requiring reoperation were recorded. An intention-to-treat analysis and an on-treatment analysis were conducted to address patients randomized to ORIF but converted to TEA intraoperatively. Twenty-one patients were randomized to each treatment group. Two died before follow-up and were excluded from the study. Five patients randomized to ORIF were converted to TEA intraoperatively because of extensive comminution and inability to obtain fixation stable enough to allow early range of motion. This resulted in 15 patients (3 men and 12 women) with a mean age of 77 years in the ORIF group and 25 patients (2 men and 23 women) with a mean age of 78 years in the TEA group. Baseline demographics for mechanism, classification, comorbidities, fracture type, activity level, and ipsilateral injuries were similar between the 2 groups. Operative time averaged 32 minutes less in the TEA group (P = .001). Patients who underwent TEA had significantly better MEPSs at 3 months (83 vs 65, P = .01), 6 months (86 vs 68, P = .003), 12 months (88 vs 72, P = .007), and 2 years (86 vs 73, P = .015) compared with the ORIF group. Patients who underwent TEA had significantly better DASH scores at 6 weeks (43 vs 77, P = .02) and 6 months (31 vs 50, P = .01) but not at 12 months (32 vs 47, P = .1) or 2 years (34 vs 38, P = .6). The mean flexion-extension arc was 107 degrees (range, 42 degrees -145 degrees) in the TEA group and 95 degrees (range, 30 degrees -140 degrees) in the ORIF group (P = .19). Reoperation rates for TEA (3/25 [12%]) and ORIF (4/15 [27%]) were not statistically different (P = .2). TEA for the treatment of comminuted intra-articular distal humeral fractures resulted in more predictable and improved 2-year functional outcomes compared with ORIF, based on the MEPS. DASH scores were better in the TEA group in the short term but were not statistically different at 2 years' follow-up. TEA may result in decreased reoperation rates, considering that 25% of fractures randomized to ORIF were not amenable to internal fixation. TEA is a preferred alternative for ORIF in elderly patients with complex distal humeral fractures that are not amenable to stable fixation. Elderly patients have an increased baseline DASH score and appear to accommodate to objective limitations in function with time.

Combined single-stage osseous and soft tissue reconstruction of the tibia with the Ilizarov method and tissue transfer.

OBJECTIVE: To determine the outcome of single-stage soft tissue and osseous reconstruction using the Ilizarov method and soft-tissue transfer. DESIGN: A retrospective review. SETTING: : A university-affiliated, tertiary-care center. PATIENTS/INTERVENTION: We identified 11 patients from a retrospective review from January 1994 to July 1999 who underwent single-stage soft tissue and osseous reconstruction using the Ilizarov method. All 11 patients had an initial traumatic mechanism to their tibia and had previous operative intervention before the combined procedure. The Ilizarov procedure was performed for infected tibial nonunion (8 cases), or complex fracture with soft-tissue loss (3 cases). MAIN OUTCOME MEASUREMENTS: Soft tissue transplant survival, union, range of motion, leg length discrepancy, the Association for the Study and Application of the Method of Ilizarov (ASAMI) score, radiographic parameters. RESULTS: There were 8 concomitant free tissue flaps and 3 local pedicled flaps. Two patients had primary bone grafting, and 5 others had addition of an antibiotic impregnated bone substitute. There were 8 cases of elective reconstructive surgery and 3 cases of acute traumatic fracture. The mean duration of Ilizarov application was 26 weeks (range, 7 to 42). Eight tibiae united primarily, and 3 healed after delayed bone grafting. There were 2 major flap complications. Both were successfully managed with repeat surgery. One patient sustained a repeat open fracture and subsequently received an amputation. According to the ASAMI score, there were 9 excellent results, 1 good result, and 1 poor result. CONCLUSION: Our study suggests that concomitant osseous and soft-tissue reconstruction with the Ilizarov technique and free or pedicled flaps is a viable option for patients with composite tissue defects.

Does delay matter? The restoration of objectively measured shoulder strength and patient-oriented outcome after immediate fixation versus delayed reconstruction of displaced midshaft fractures of the clavicle.

Outcome after surgical treatment for nonunion and malunion of midshaft displaced clavicle fractures has generally been described as favorable and equal to results of acute repair. This assumption has been based on subjective criteria, however, and no direct comparison is available in the literature. This study used objective measurements of limb function to compare outcome in patients who underwent delayed operative intervention for nonunion and malunion with the outcome of patients who underwent immediate open reduction and internal fixation after displaced clavicle fracture. All patients had sustained completely displaced, closed, isolated midshaft clavicle fractures, of whom 15 had undergone acute open reduction and internal fixation with a compression plate at a mean of 0.6 months after injury (acute group). Another 15 patients had undergone delayed reconstruction with open reduction, bone grafting, and compression plate fixation for nonunion or malunion a mean of 63 months after injury (delayed group). The 2 groups were similar in age, gender, original fracture characteristics, and mechanism of injury. Complete assessment included standard history and physical examination, the Disabilities of the Arm, Shoulder and Hand (DASH) score and Constant Shoulder Score, subjective rating of outcome satisfaction, and objective muscle strength testing using a previously validated and published protocol on the Baltimore Therapeutic Equipment (BTE) work simulator. There were no significant differences between acute fixation and delayed reconstruction groups with regard to strength of shoulder flexion (acute, 94%; delayed, 93%; P = .82), shoulder abduction (acute, 97%; delayed, 97%; P = .92), external rotation (acute, 97%; delayed, 90%; P = .11), or internal rotation (acute, 98%; delayed, 96%; P = .55). Constant scores in the acute group were superior (acute, 95; delayed, 89; P = .02), but differences in DASH scores were not significant (acute, 3.0; delayed, 7.2; P = .15). Shoulder flexion muscle endurance was significantly decreased in the delayed group (acute, 109%; delayed, 80%; P = .05). Differences in muscle endurance in other planes were not significantly different (abduction endurance: acute, 107%; delayed, 81%; P = .24). Both groups rated their satisfaction with the procedure as excellent. Late reconstruction of nonunion and malunion after displaced midshaft fractures of the clavicle is a reliable and reproducible procedure that results in restoration of objective muscle strength similar to that seen with immediate fixation; however, there are subtle decreases in endurance strength and outcome compared with acute fracture repair. This information should not be used to justify primary operative repair in isolation but is useful in decision-making when counseling patients with displaced midshaft fractures of the clavicle.

Deficits following nonoperative treatment of displaced midshaft clavicular fractures.

BACKGROUND: Displaced fractures of the midpart of the clavicular shaft are generally treated nonoperatively, and few functional deficits have been reported. Whereas prior investigators have presented radiographic and surgeon-based outcomes, we used a patient-based outcome questionnaire and objective muscle-strength testing to evaluate a series of patients who had received nonoperative care for a displaced midshaft fracture of the clavicle. METHODS: We identified thirty patients (twenty-two men and eight women with a mean age of thirty-seven years) who had sustained a displaced midshaft fracture of the clavicle. All patients were treated nonoperatively. At a mean of fifty-five months, and a minimum of twelve months, outcomes were measured with the Constant shoulder score and the DASH (Disabilities of the Arm, Shoulder and Hand) patient questionnaire. In addition, objective shoulder muscle-strength testing was performed with the Baltimore Therapeutic Equipment Work Simulator, with the uninjured arm serving as a control. RESULTS: The range of motion was well maintained, with flexion averaging 170 degrees +/- 20 degrees and abduction averaging 165 degrees +/- 25 degrees . Compared with the strength of the uninjured shoulder, the strength of the injured shoulder was reduced to 81% for maximum flexion, 75% for endurance of flexion, 82% for maximum abduction, 67% for endurance of abduction, 81% for maximum external rotation, 82% for endurance of external rotation, 85% for maximum internal rotation, and 78% for endurance of internal rotation (p < 0.05 for all values). The mean Constant score was 71 points, and the mean DASH score was 24.6 points, indicating substantial residual disability. CONCLUSIONS: Traditionally, good results with minimal functional deficits have been reported following nonoperative treatment of clavicular fractures. However, surgeon-based methods of evaluation may be insensitive to loss of muscle strength. We detected residual deficits in shoulder strength and endurance in this patient population, which may be related to the significant level of dysfunction detected by the patient-based outcome measures.

Patient-oriented functional outcome after repair of distal biceps tendon ruptures using a single-incision technique.

Using a patient-oriented outcome questionnaire, in addition to standard outcome measures, we sought to determine the outcome of patients who had repair of a complete rupture of the distal biceps tendon via a single anterior incision technique with suture anchors. We identified 62 patients who were treated operatively by a single surgeon over an 8-year period for a diagnosis of complete rupture of the distal biceps tendon. Of the patients, 9 could not be located for final follow-up, and 53 of 62 (85%) participated in the study. All patients were men, and their mean age was 42 years. All repairs were performed via a single anterior incision by use of 2 suture anchors in the bicipital tuberosity on an outpatient basis. There were 4 complications (4/53 [7.5%]): 1 wound infection, 2 transient paresthesias in the lateral cutaneous nerve distribution, and 1 posterior interosseous nerve palsy that resolved in 6 weeks (no reoperations). There were no reruptures, and no patient lost more than 5 degrees of elbow flexion- extension or forearm rotation. All patients completed the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire. The mean DASH score was 8.2 +/- 11.6 (95% CI, 5.2 to 11.9), which was similar to the mean DASH score in population controls of 6.2 (DASH User Manual). The strengths of our study include the consistent surgical technique by a single surgeon, the large number of patients, and the use of a patient-oriented outcome measure. Distal biceps tendon rupture repair via a single-incision technique with suture anchors was effective in restoring injured arms to normal, as measured by limb-specific patient-oriented measures, with minimal morbidity and a low complication rate.

Standard surgical protocol to treat elbow dislocations with radial head and coronoid fractures. Surgical technique.

BACKGROUND: The results of elbow dislocations with associated radial head and coronoid fractures are often poor because of recurrent instability and stiffness from prolonged immobilization. We managed these injuries with a standard surgical protocol, postulating that early intervention, stable fixation, and repair would provide sufficient stability to allow motion at seven to ten days postoperatively and enhance functional outcome. METHODS: We retrospectively reviewed the results of this treatment performed, at two university-affiliated teaching hospitals, in thirty-six consecutive patients (thirty-six elbows) with an elbow dislocation and an associated fracture of both the radial head and the coronoid process. Our surgical protocol included fixation or replacement of the radial head, fixation of the coronoid fracture if possible, repair of associated capsular and lateral ligamentous injuries, and in selected cases repair of the medial collateral ligament and/or adjuvant-hinged external fixation. Patients were evaluated both radiographically and with a clinical examination at the time of the latest follow-up. RESULTS: At a mean of thirty-four months postoperatively, the flexion-extension arc of the elbow averaged 112 degrees +/- 11 degrees and forearm rotation averaged 136 degrees +/- 16 degrees . The mean Mayo Elbow Performance Score was 88 points (range, 45 to 100 points), which corresponded to fifteen excellent results, thirteen good results, seven fair results, and one poor result. Concentric stability was restored to thirty-four elbows. Eight patients had complications requiring a reoperation: two had a synostosis; one, recurrent instability; four, hardware removal and elbow release; and one, a wound infection. CONCLUSIONS: Use of our surgical protocol for elbow dislocations with associated radial head and coronoid fractures restored sufficient elbow stability to allow early motion postoperatively, enhancing the functional outcome. We recommend early operative repair with a standard protocol for these injuries.

Standard surgical protocol to treat elbow dislocations with radial head and coronoid fractures.

BACKGROUND: The results of elbow dislocations with associated radial head and coronoid fractures are often poor because of recurrent instability and stiffness from prolonged immobilization. We managed these injuries with a standard surgical protocol, postulating that early intervention, stable fixation, and repair would provide sufficient stability to allow motion at seven to ten days postoperatively and enhance functional outcome. METHODS: We retrospectively reviewed the results of this treatment performed, at two university-affiliated teaching hospitals, in thirty-six consecutive patients (thirty-six elbows) with an elbow dislocation and an associated fracture of both the radial head and the coronoid process. Our surgical protocol included fixation or replacement of the radial head, fixation of the coronoid fracture if possible, repair of associated capsular and lateral ligamentous injuries, and in selected cases repair of the medial collateral ligament and/or adjuvant hinged external fixation. Patients were evaluated both radiographically and with a clinical examination at the time of the latest follow-up. RESULTS: At a mean of thirty-four months postoperatively, the flexion-extension arc of the elbow averaged 112 degrees +/- 11 degrees and forearm rotation averaged 136 degrees +/- 16 degrees. The mean Mayo Elbow Performance Score was 88 points (range, 45 to 100 points), which corresponded to fifteen excellent results, thirteen good results, seven fair results, and one poor result. Concentric stability was restored to thirty-four elbows. Eight patients had complications requiring a reoperation: two had a synostosis; one, recurrent instability; four, hardware removal and elbow release; and one, a wound infection. CONCLUSIONS: Use of our surgical protocol for elbow dislocations with associated radial head and coronoid fractures restored sufficient elbow stability to allow early motion postoperatively, enhancing the functional outcome. We recommend early operative repair with a standard protocol for these injuries.

Midshaft malunions of the clavicle. Surgical technique.

BACKGROUND: The purpose of this study was to analyze the functional results of corrective osteotomy of a malunited clavicular fracture in patients with chronic pain, weakness, neurologic symptoms, and dissatisfaction with the appearance of the shoulder. METHODS: We identified fifteen patients (nine men and six women with a mean age of thirty-seven years) who had a malunion following nonoperative treatment of a displaced midshaft fracture of the clavicle. The mean time from the injury to presentation was three years (range, one to fifteen years). Outcome scores revealed major residual deficits. The mean amount of clavicular shortening was 2.9 cm (range, 1.6 to 4.0 cm). All patients underwent corrective osteotomy of the malunion through the original fracture line and internal fixation. RESULTS: At the time of follow-up, at a mean of twenty months (range, twelve to forty-two months) post-operatively, the osteotomy site had united in fourteen of the fifteen patients. All fourteen patients expressed satisfaction with the result. The mean DASH (Disabilities of the Arm, Shoulder and Hand) score for all fifteen patients improved from 32 points preoperatively to 12 points at the time of follow-up (p = 0.001). The mean shortening of the clavicle improved from 2.9 to 0.4 cm (p = 0.01). There was one nonunion, and two patients had elective removal of the plate. CONCLUSIONS: Malunion following clavicular fracture may be associated with orthopaedic, neurologic, and cosmetic complications. In selected cases, corrective osteotomy results in a high degree of patient satisfaction and improves patient-based upper-extremity scores.

The effect of smoking on clinical outcome and complication rates following Ilizarov reconstruction.

OBJECTIVE: To determine the effect of smoking on outcome and complication rates following Ilizarov reconstruction. DESIGN: We performed a retrospective review of 84 adult patients (86 limbs) who underwent Ilizarov reconstruction. There were 39 "limbs" in nonsmokers and 47 "limbs" in active smokers. Complications and an outcome score based on ASAMI (Association for the Study and Application of the Methods of Ilizarov) criteria were recorded for each patient. DATA ANALYSIS AND RESULTS: There were 35 major complications including 15 malunions/nonunions, 7 refractures, 8 persisting infections, and 5 amputations. Results were measured using the ASAMI outcome scale. There were significantly more poor results in the smoking group than in the nonsmoking group (18/47, 38% versus 4/39, 10%; P = 0.003). Seven of eight patients with persisting infection were smokers (P = 0.049). There was a higher incidence of nonunion in the smoking group (P = 0.031). All five amputations were in smokers (P = 0.035). CONCLUSION: Smokers had a higher percentage of poor results (P = 0.01), due primarily to higher complication rates. Smoking is a significant, potentially remediable risk factor for failure following Ilizarov reconstruction, and cessation strategies are of paramount importance prior to initiating treatment.

Midshaft malunions of the clavicle.

BACKGROUND: The purpose of this study was to analyze the functional results of corrective osteotomy of a malunited clavicular fracture in patients with chronic pain, weakness, neurologic symptoms, and dissatisfaction with the appearance of the shoulder. METHODS: We identified fifteen patients (nine men and six women with a mean age of thirty-seven years) who had a malunion following nonoperative treatment of a displaced midshaft fracture of the clavicle. The mean time from the injury to presentation was three years (range, one to fifteen years). Outcome scores revealed major residual deficits. The mean amount of clavicular shortening was 2.9 cm (range, 1.6 to 4.0 cm). All patients underwent corrective osteotomy of the malunion through the original fracture line and internal fixation. RESULTS: At the time of follow-up, at a mean of twenty months (range, twelve to forty-two months) postoperatively, the osteotomy site had united in fourteen of the fifteen patients. All fourteen patients expressed satisfaction with the result. The mean DASH (Disabilities of the Arm, Shoulder and Hand) score for all fifteen patients improved from 32 points preoperatively to 12 points at the time of follow-up (p = 0.001). The mean shortening of the clavicle improved from 2.9 to 0.4 cm (p = 0.01). There was one nonunion, and two patients had elective removal of the plate. CONCLUSIONS: Malunion following clavicular fracture may be associated with orthopaedic, neurologic, and cosmetic complications. In selected cases, corrective osteotomy results in a high degree of patient satisfaction and improves patient-based upper-extremity scores.

The use of an antibiotic-impregnated, osteoconductive, bioabsorbable bone substitute in the treatment of infected long bone defects: early results of a prospective trial.

OBJECTIVE: We sought to evaluate the use of a bioabsorbable, tobramycin-impregnated bone graft substitute (calcium sulfate alpha-hemihydrate pellets) in the treatment of patients with infected bony defects and nonunions. STUDY DESIGN/METHODS: Twenty-five patients (15 male and 10 female, mean age 43 years (range 27-69 years) requiring surgical debridement of culture-positive long bone infection (16 with associated nonunion) were entered into an ongoing consecutive, prospective clinical trial. Involved bones included the tibia ( 15), femur ( 6), ulna ( 3), and humerus ( 1). All defects were posttraumatic in origin, and each patient had had previous surgery at the involved site (mean 4.3 surgeries; range 1-8 surgeries). The duration of infection ranged from 4 months to 20 years (mean 43 months). According to the Cierny-Mader classification system, there was 1 stage I (medullary osteomyelitis), 6 stage III (localized osteomyelitis), and 18 stage IV (diffuse osteomyelitis) lesions. There were 4 normal (A) hosts and 21 locally and/or systemically compromised (B) hosts. Mean bone defect/void was 30.5 cm (range 3-192 cm ). RESULTS: Mean follow-up was 28 months (range 20-38 months). Radiographically, pellets were resorbed at a mean of 2.7 months postoperatively. Infection was eradicated in 23 of 25 patients (92%). Isolated bony defects healed in all nine patients without further treatment. Fourteen of 16 patients with nonunion achieved union, although nine required autogenous bone grafting. Union was achieved in five of seven nonunion patients treated with bone graft substitute in isolation. Complications included refracture (three), recurrence of infection (two), persistent nonunion (two), and superficial wound necrosis (one). Eight patients developed sterile draining sinuses that healed upon radiographic resorption of the pellets. CONCLUSIONS: In patients with posttraumatic osteomyelitis, the bone graft substitute was effective in eradicating bone infection in 23 of 25 patients. Isolated bony defects healed reliably (nine of nine) following addition of bone graft substitute alone. The role of the bone graft substitute in isolation in the treatment of nonunion is unclear at present.

Femoral intramedullary nailing: comparison of fracture-table and manual traction. a prospective, randomized study.

BACKGROUND: The purpose of this study was to compare manual traction and fracture-table traction for the reduction and nailing of femoral shaft fractures. We evaluated the quality of the reduction, operative time, complications, and functional status of the patient. METHODS: Eighty-seven consecutive adult patients with a unilateral fracture of the femoral diaphysis that did not extend into the knee joint or proximal to the lesser trochanter were enrolled in the study. Patients who were transferred to our institution more than forty-eight hours after injury; those with multiple-system injuries, injury to the ipsilateral lower extremity, or pathological fracture; and those who were unable or unwilling to provide consent or to return for follow-up were excluded. Forty-five patients were randomized to manual traction and forty-two, to fracture-table traction; all were treated in the supine position. The number of surgical assistants, operative and fluoroscopy time, complications, functional scores, and other outcomes were recorded. RESULTS: There were no significant differences between the groups with respect to age, gender, Glasgow Coma Score, Injury Severity Score, side or mechanism of injury, fracture type, or time from injury to treatment. Internal malrotation was significantly more common when the fracture table had been used: twelve (29%) of the forty-two femora were internally rotated by >10 compared with three (7%) of the forty-five treated with manual traction (p = 0.007). Total operative time, from the beginning of the patient positioning to the completion of the skin closure, was decreased from a mean of 139 minutes (range, 100 to 212 minutes) when the fracture table was used to a mean of 119 minutes (range, sixty-five to 180 minutes) when manual traction was used (p = 0.033). There was no significant difference between the two treatment groups with regard to the number of assistants per case (mean two; range, zero to three), fluoroscopy time, other complications including femoral shortening or lengthening, or functional status of the patient at one year. CONCLUSIONS: Compared with fracture-table traction with the patient in a supine position, manual traction for intramedullary nailing of isolated fractures of the femoral shaft is an effective technique that decreases operative time and improves the quality of the reduction.

Intramolecular Homolytic Translocation Chemistry: An ab Initio Study of 1,n-Halogen Atom Transfer Reactions in Some omega-Haloalkyl Radicals.

Ab initio calculations using all-electron (3-21G(()()), 6-311G) and pseudopotential (DZP) basis sets, with (MP2, QCISD) and without (UHF) the inclusion of electron correlation, predict that 1,n-halogen transfer reactions in the 5-halo-1-pentyl (6), 6-halo-1-hexyl (7), and 7-halo-1-heptyl radicals (8) proceed via C(s)- and/or C(2)-symmetric transition states (9-11), except for the 5-bromo-1-pentyl (6, X = Br) radical for which a C(s)-symmetric transition state (9) was located only at the UHF/3-21G(()()) level of theory and the 5-iodo-1-pentyl radical (6, X = I) for which no transition state (9) could be located at any level of theory used in this study. Energy barriers for these translocation reactions of between 120.0 (1,7-iodine transfer) and 191.0 kJ mol(-)(1) (1,5-chlorine transfer) are predicted at the MP2/DZP level of theory; QCISD/DZP (single-point) calculations predict similar energy barriers. These high energy barriers are a consequence of unfavorable factors associated with ring size and long carbon-halogen separations in transition states (9-11) which lead to significant deviations from the collinear arrangement of attacking and leaving radicals preferred in transition states involved in homolytic substitution reactions at halogen. The dependence of transition state energy on attack angle at halogen has been explored for the attack of methyl radical at chloromethane. At the MP2/DZP level of theory, attack angles of between 80 and 90 degrees are calculated to lead to increases in energy barrier of about 100 kJ mol(-)(1) when compared with the collinear (180 degrees ) arrangement of attacking and leaving groups. The mechanistic implications of these predictions are discussed.