POSTERIOR DYNAMIC DISTRACTION DEVICE FOR THE TREATMENT OF ADOLESCENT IDIOPATHIC SCOLIOSIS: PRELIMINARY RESULTS FROM A PROSPECTIVE CLINICAL STUDY

After receiving Humanitarian Use Device approval from the US FDA in 2019, a prospective study was undertaken to evaluate the safety and effectiveness of a PDDD for use in AIS. This report presents safety data for all patients treated to date and efficacy data for those with a two-year follow-up. From 13 US sites, 149 patients with AIS (Lenke 1 and 5), major Cobb 35 to 60°, less than or equal to 30° on side bending, and kyphosis less than 55°, were prospectively enrolled between June 2020 and April 2023. Demographics, safety, and deformity data were tracked. Safety and perioperative data were available for 149 patients, mean age 14.8 years and 75% female. On average, the procedure time was 112±34 min and estimated blood loss was 38.1±33.9 ml. The preoperative Cobb angle was 47.5°±7.3° with flexibility to 17.6°±6.6°. The Cobb angle at the first erect visit was 18.7°±7.0°. Mean hospitalization was 1.3 days. Two patients were admitted to the ICU for one day. Twenty-one patients (14.1%) had 23 reoperations, which included 14 PDDD revisions (9.4%) and seven PDDD removals (4.7%). Two patients were converted to posterior spinal fusion (1.3%). The main reasons included implant breakage (n=8), curve progression (n=4), infection (n=3), and screw migration or misplacement (n=3). One patient had a dural leak and was also admitted one-month post-surgery for wound irrigation and debridement. Both events resolved without sequelae. No major neurologic issues were noted. Twenty-five patients had minimum two-year follow-up, 16 of them Lenke 1 and nine Lenke 5. The subgroup characteristics were similar to the entire cohort. (Table 1). At two years, curve correction to ≤30° was noted for 92% of the cohort and was maintained at the last follow-up (P=0.629). Five of the 25 patients (20%) had revision surgery, three implant revisions and two implant removals. PDDD correction of Cobb angles was significant and durable at two-year follow-up for the majority of patients, with revision rates similar to those reported for other non-fusion scoliosis procedures and shows promise in the avoidance of spinal fusion. Ongoing study is needed to determine the true incidence of long-term complications. For any figures or tables, please contact the authors directly.