From 1965 to 1987, 84 spinal muscular atrophy patients were followed at Rancho Los Amigos Medical Center (RLAMC). Twenty-seven patients were excluded from this study due to insufficient medical documentation (16), lack of follow-up (5), and death (6); leaving 57 patients in the general study group. Group I (34 patients) had posterior spinal fusion (PSF) with Harrington rod instrumentation (HRI); mean age at surgery was 12 years, average preoperative curve was 57 degrees, average postoperative correction was 42%, with a loss of correction of 9 degrees. The complication rate in this group was 35%. The average follow-up interval was 9 years (range, 4-19 years). Group II (six patients) underwent PSF with Luque segmental spinal instrumentation (SSI); mean age at surgery was 11 years, preoperative curves averaged 37 degrees, average postoperative correction was 42% with a loss of correction of 3 degrees. The complication rate in this group was 16%. Follow-up was 3.5 years. Physical therapy and occupational therapy evaluations were done preoperatively and postoperatively at 2- and 5-year intervals. Information was gathered in three categories: 1) ambulation, 2) equipment use, and 3) functional activities. After fusion, sitting tolerance was maintained but additional use of mobile arm supports, lapboards, and reaching aides was necessary for all patients. The ability to perform activities such as drinking, self-feeding, and self-hygiene declined during the 2 years immediately following surgery but improved by 5 years. Surgical patients never approached their preoperative skill levels. Therapy evaluations further demonstrated that there were no difference in function between either operative group.