Pressure mapping as an outcome measure for spinal surgery in patients with myelomeningocele.

STUDY DESIGN

A retrospective analysis of prospectively collected data on a cohort of 19 myelomeningocele patients undergoing spino-pelvic deformity surgery.

OBJECTIVE

To examine if greater curve correction with third generation spinal implants correlate with improved pressure distribution and resolution, or prevention of skin ulcerations in myelomeningocele patients.

SUMMARY OF BACKGROUND DATA

Children born with myelomeningocele have often complex spino-pelvic deformities leading to skin ulcerations.

METHODS

A cohort of 19 consecutive wheelchair dependent patients with myelodisplastic spinal deformities, who underwent spinal surgery, was prospectively followed with regular pressure mappings for a minimum of 2 years. Standard spino-pelvic radiologic measurements were obtained. Sitting pressure mappings were obtained over the study period using the Force Sensitive Applications from Vista Medical (Winnipeg, Manitoba, Canada). Statistical analysis was done using SAS (SAS Institute Inc, Cary, NC). Paired t-test and Wilcox on Signed Rank test was used where applicable. Significance was taken to be P<0.05.

RESULTS

Surgery significantly corrected radiographic parameters, specifically, Cobb angle (52%), pelvic obliquity (89%), and to a lesser degree pelvic tilt. Stratifying the data based on fixation type showed that the M-W construct was able to significantly correct pelvic obliquity. While significant changes in radiographic variables were observed after surgery, this was not the case with the various pressure mapping variables. Only minor changes after surgery were observed in the average pressure, maximum pressure, and variable coefficient of pressure. What was observed was an improvement in the overall distribution from anterior/posterior and right/left. While the values only approached statistical significance (P=0.053) for right/left, however, this did not appear to be clinically significant regarding skin ulceration.

CONCLUSION

Despite significant surgical corrections in radiographic parameters, these resulted in small changes in pressure distributions and do not appear to influence skin ulceration in the myelomeningocele patient. Pressure mapping may not be a useful tool in predicting outcome of spinal surgery. Factors which were proven to influence pressure distribution are the sagittal pelvic orientation and also achieving coronal spine balance.