MUSCULOSKELETAL FUNCTIONAL OUTCOMES IN CHILDREN WITH SACRAL AGENESIS

Participants: F.A. Farley, M. Caird, J.M. Hall, D. Bloom, J.M. Park

Keywords: congenital spinal anomalies, lower limb deformities, neuropathic bladder

Introduction

Sacral agenesis is a rare disorder with reported incidence varying between 0.01 and 0.05 per 1000 live births. It is characterized by partial or complete absence of the sacrum, the lumbar spine, and neural elements. Patients with sacral agenesis can be variably affected with associated abnormalities including deformities of the lower extremities, genitourinary abnormalities, lower gastrointestinal tract anomalies, and congenital scoliosis. From a urologic standpoint, the impaired development of sacral nerves results in a variety of patterns of neuropathic bladder. Orthopaedic problems may include foot deformities, knee contractures, hip contractures and dislocation, scoliosis, and spinopelvic instability.

Motor deficits and musculoskeletal deformities associated with sacral agenesis have been well characterized, but the functional outcomes associated with these anomalies have not been well described. An accurate picture of the functional limitations associated with sacral agenesis may help clinicians develop treatment strategies that will enhance musculoskeletal function and increase quality of life in these patients. The specific aims of this retrospective study are to:

1. Describe musculoskeletal functional outcomes in sacral agenesis patients with respect to: 1) basic mobility, 2) physical ability to perform activities of daily living and engage in sports activities, 3) pain levels, 4) satisfaction with symptoms, and 5) treatment expectations.

2. Compare standardized musculoskeletal outcome scores in sacral agenesis patients with age-matched outcome scores in other orthopaedic patients using normative data collected by AAOS and the New England Medical Center.

Materials and Methods

Sample Based on the incidence rate of sacral agenesis and the number of past years available for a UMHS medical records search, approximately forty patients are expected to meet criteria for study enrollment. An attempt will be made to contact all eligible patients. Given the limited involvement that will be required of subjects seventy-five percent of eligible patients are expected to participate.

Measures: Standardized orthopaedic outcomes questionnaires will be used to collect information on current functioning. Subscale scores for: 1) basic mobility, 2) physical ability to perform activities of daily living and engage in sports activities, 3) pain levels, 4) satisfaction with symptoms, and 5) treatment expectations, are generated by these instruments. These outcomes questionnaires have been used by AAOS, and by an orthopaedic group at the New England Medical Center, to collect normative data on clinical populations with other types of orthopaedic conditions. These normative orthopaedic data will provide the basis for comparison of the outcomes measures in our study sample.

Statistical Power: For the purpose of sample size/statistical power calculations, a difference of at least two standard deviations on mean subscale scores between the study sample and the normative sample(s) was assumed to be clinically significant. Using this estimate, a sample size of 30 would yield 93% statistical power. If fewer than 30 subjects are enrolled, new power estimates, based on the measured differences in subscale scores, will be calculated for the actual sample size.

Statistical comparisons: Since the sample is expected to be small and therefore not likely to meet the assumptions of standard parametric statistical tests, a nonparametric test, the Mann-Whitney U test, will be used to compare subscale scores between the study sample and the AAOS and/or the New England Medical Center orthopaedic normative samples.

Progress

IRB approval has been obtained and a medical records search has been initiated. Subject recruitment will begin as soon as eligible patients have been identified.