[Overview of design and construction of hypertensive disorders of a pregnancy-cohort in Shenzhen]

Hypertensive disorder of pregnancy (HDP) involves two major public health issues: mother-infant safety and prevention and controlling major chronic disease. HDP poses a serious threat to maternal and neonatal safety, and it is one of the leading causes of maternal and perinatal morbidity and mortality worldwide, as well as an important risk factor for long-term cardiovascular disease (CVD). In order to explore effective strategies to prevent and control the source of CVD and reduce its risk, we have established a cohort of HDPs in Shenzhen for the primordial prevention of CVD. The construction of the HDP cohort has already achieved preliminary progress till now. A total of 2 239 HDP women have been recruited in the HDP cohort. We have established a cohort data management platform and Biobank. The follow-up and assessment of postpartum cardiovascular metabolic risk in this cohort has also been launched. Our efforts will help explore the pathophysiological mechanism of HDP, especially the pathogenesis and precision phenotyping, prediction, and prevention of pre-eclampsia, which, therefore, may reduce the risk of adverse pregnancy outcomes, and provide a bridge to linking HDP and maternal-neonatal cardiovascular, metabolic risk to promote the cardiovascular health of mothers and their infants.

A population-based study of reoperations after back surgery

STUDY DESIGN

Longitudinal follow-up study of back surgery reoperations using an administrative database.

OBJECTIVES

To identify population-based rates and factors that determine the need for reoperation after back surgery.

SUMMARY OF BACKGROUND DATA

Reoperation after lumbar surgery has poorer results than the initial surgery, yet the population-based incidence and determinants of reoperation are not known. Reported rates of reoperation are derived from retrospective case series and range from 4% to 15%. There are conflicting data on the rate of reoperation after different types of initial surgery.

METHODS

All patients who had back surgery in the Province of Ontario (population 10,000,000) between April 1990 and March 1991 were identified using hospital discharge abstracts and an ICD-9 code algorithm. Patients who had undergone prior surgery were excluded. Patients were observed from the index operation to subsequent readmission and reoperation with a maximal time to follow-up examination of 4 years. Basic demographic information and information regarding diagnoses, surgery performed, complications, comorbid factors, reoperation diagnosis, and surgery type were obtained. Patients were divided into surgical treatment groups, and their subsequent reoperations were identified. Multivariate analysis using proportional hazards modeling was conducted.

RESULTS

The index surgery group consisted of 4,722 patients, of whom 449 (9.5%) underwent reoperations in the follow-up period. Complications from surgery were significantly higher in the fusion and fusion with decompression groups. The reoperation rate was not significantly different among individual surgery groups. Diagnosis, operation performed, complications after the index surgery, comorbid conditions, and sex did not predict the need for spine reoperation. Younger age was predictive of the likelihood of reoperation (P = 0.04)

CONCLUSION

The incidence of reoperation after back surgery is independent of diagnosis and type of surgery performed. Despite different anatomic reasons for surgical intervention, the success of different types of surgery are not influenced by the factors identified in this study. More extensive surgery does not prevent nor predispose a patient to the need for further surgery.

Insertional torque and pull-out strengths of conical and cylindrical pedicle screws in cadaveric bone

STUDY DESIGN

Insertion torque and pull-out strengths of conical and cylindrical pedicle screws were compared in human cadaveric vertebral bodies.

OBJECTIVES

To compare the performance of the conical design with the cylindrical design, and to determine whether insertional torque correlates with pull-out strength.

SUMMARY OF BACKGROUND DATA

A tapered pedicle screw design may lessen the likelihood of implant failure. Its effect on thread purchase is not known. Previous studies of cylindrical designs on the relation between insertion torque and pull-out strength have been conducted in bovine and synthetic bone.

METHODS

Seventy-eight pedicles were assigned randomly to one of the following pedicle screw: Texas Scottish Rite Hospital (Sofamor-Danek, Memphis, TN), Steffee VSP (Acromed, Cleveland, OH), Diapason (Dimso, Paris, France), AO Schanz (Synthes, Paoli, PA), or Synthes USS (Synthes, Paoli, PA). Pedicle screws were inserted with a torque screwdriver. Each screw was extracted axially from the pedicle at a rate of 1.0 mm/sec until failure using an MTS machine (Bionix 858, Minneapolis, MN). Force data were recorded.

RESULTS

The conical design had the highest insertion torque. There were no significant differences in pull-out between any of the screw types. Correlation between insertional torque and pull-out strength was statistically significant only with the Texas Scottish Rite Hospital and Steffee VSP in L4 and AO Schanz in L5.

CONCLUSIONS

A conical screw profile increases insertion torque, although insertional torque is not a reliable predictor of pull-out strength in cadaveric bone. Screw profile (with similar dimensions) has little effect on straight axial pull-out strengths in cadaveric bone.

Computer-aided pedicle screw placement using frameless stereotaxis

STUDY DESIGN

In vitro assessment of accuracy and reliability of frameless stereotaxis for insertion of pedicle screws in human cadaveric lumbar spine.

OBJECTIVES

To assess a new method of targeting and placing pedicle screws in a human cadaver study.

SUMMARY OF BACKGROUND DATA

Pedicle screw instrumentation is common. Complications may occur from improper placement of screws. Even when performed by experienced spinal surgeons, improper placement can occur in 5.2% of pedicles instrumented. Development of computer-guided methods of pedicle screw insertion may decrease this complication rate.

METHODS

The technique used preoperative computed tomography scans together with a commercial neurosurgical navigational computer system to assist in placing guidewires in the pedicles. A section of human cadaver spine was first scanned and the data transferred to the workstation. The image data set and physical specimen were then registered by using an instrumented articulated arm to identify selected points on the specimen and randomly sample surface points. Eight highly repeatable locations on each vertebral body were found to be suitable for registration, but better overall accuracy was obtained when surface matching was used in combination with these points. Under guidance of image on the computer, Kirschner wires were inserted into the pedicles of four vertebral bodies. The spine was rescanned, and the planned and resulting positions of the wires compared.

RESULTS

The average distance between the planned and resulting wire entry point was 1.2 mm, with an average difference in planned and resulting trajectories of 6.0 degrees.

CONCLUSIONS

Computer-aided pedicle screw instrumentation is feasible. Further technical points require clarification before widespread use is possible.

Lower limb compartment syndrome: course after delayed fasciotomy

OBJECTIVE

To determine the end result of patients who underwent delayed fasciotomy, i.e., more than 35 hours for an established lower limb compartment syndrome.

DESIGN

A retrospective review of patients undergoing delayed treatment for a closed injury of the lower extremity, where fasciotomy should ideally have been performed earlier.

MATERIALS AND METHODS

Nine fasciotomies in five patients were identified where there was a delay of more than 35 hours after the injury. The average ischemic time was 56 hours (range 35-96 hours).

RESULTS

One patient died of multiorgan failure and septicemia. The remaining four patients required lower limb amputation, because of local infection and septicemia. The one late amputation was performed 6 months after the injury, because the patient was left with a functionless insensate foot. Where recognition of an established compartment syndrome is delayed for more than 8 to 10 hours, we propose that the traditional inevitable fasciotomy be reassessed.

Open posterior dislocation of the lumbosacral junction. A case report

STUDY DESIGN

A patient with open posterior dislocation of the lumbosacral junction is reported.

OBJECTIVES

Treatment with primary anterior open reduction with internal fixation followed by delayed posterior stabilization and fusion.

SUMMARY OF BACKGROUND DATA

This injury has been reported previously on two occasions; however, anterior stabilization was not used. In this case, anterior fixation was necessary because of the posterior soft tissue contamination.

METHODS

After an anterior open reduction of L5-S1, stabilization was performed using instrumentation. Posterior wound care was then performed, with delayed posterior fusion and instrumentation of L5-S1 at 2 weeks.

RESULTS

At 18 months there was solid fusion of the lumbosacral junction with no evidence of infection.

CONCLUSIONS

Satisfactory results were obtained when principles of open fracture management were followed. Primary anterior stabilization allowed appropriate wound care. Definitive posterior stabilization and fusion can be done when soft tissue stability is obtained.

"Splint-top" fracture of the forearm: a description of an in-line skating injury associated with the use of protective wrist splints

Upper extremity injuries are commonly seen in the sport of in-line skating. The use of protective equipment, including wrist splints, has been advocated as a means to decrease both the incidence and severity of upper extremity injuries in this sport. We report on four cases of open forearm fractures in the in-line skaters that occurred adjacent to the proximal border of the wrist splints. The unusual nature of these injuries and the location of the fractures in relation to the location of the splints suggest that the two may be mechanistically related. The splint and distal forearm may act as a single unit to convert the impact from the level of the wrist to a torque moment, with the fulcrum located at the proximal border of the splint. The energy from the fall is then dissipated by the fracturing of the forearm bones at this level. These cases suggest that the use of wrist splints may be associated with their own specific set of injury patterns.

Fracture at the iliac bone graft harvest site after fusion of the spine

To determine the clinical features of iliac crest graft harvest site fracture after spinal arthrodesis, a retrospective study surveying the spinal surgery performed at Case Western Reserve University was performed. Approximately 200 cervical spine fusions and an equal number of lumbar spine fusions are performed in that center each year. Between November 1985 and March 1991, 14 patients were identified with fractures at an iliac crest graft harvest site. All but 1 of these patients were female. They had an average age at surgery of 61 years old (range, 24-76 years old). Twelve patients had cervical procedures (2 posterior and 10 anterior fusions). The patients with anterior cervical fusions experienced avulsion fractures of the anterior superior iliac spine. One patient with a posterior occipital cervical fusion experienced bilateral posterior iliac wing fractures, and 1 with posterior atlantoaxial fusion resulted in a unilateral iliac wing fracture. All patients were treated nonoperatively with protection of weight bearing until resolution of pain. All patients had satisfactory results at final followup ranging from 6 months to 5 years. Three patients had residual mild pain that did not affect activities of daily living. The remainder were pain free. Few series of fractures of the pelvis after graft harvest are reported. This group of patients had satisfactory results with nonoperative treatment. Older female patients with osteopenic bone are prone to iliac graft site fracture, and particular care should be exercised in this population.