Implant density in adolescent idiopathic scoliosis: a meta-analysis of clinical and radiological outcomes

Adolescent idiopathic scoliosis (AIS) affects 1–3% of adolescents, and treatment approaches, including the density of constructs in surgical fusion, vary among orthopedic surgeons. Studies have sought to establish whether high-density or low-density constructs offer superior clinical and radiological outcomes, yet conclusive results are lacking. This meta-analysis aims to provide a definitive answer to the controversial and ambiguous question surrounding the efficacy of different pedicle screw densities in treating AIS.

PubMed, Cochrane, and Google Scholar (page 1–20) were searched till December 2023. The studied outcomes were Major Cobb angle, major curve correction, lumbar curve, kyphosis (T5–T12), lumbar lordosis, coronal balance, LIV Tilt angle, TAV translation, LAV translation, apical trunk rotation, trunk shift, SRS-22, operative time, blood loss, complications and cost.

Twenty-four studies (total of 1985 patients, 1045 in LD group and 940 in HD group) were included in this meta-analysis. A statistically significant better improvement in ATR (p = 0.02) and LIV tilt angle (p = 0.02) was seen in the high-density group. On the other hand, longer operative time (p = 0.002), blood loss (p = 0.0004) and costs (p = 0.02) were seen in the high-density group. No difference was seen in the remaining radiographic and clinical outcomes between both surgeries.

Both low-density (LD) and high-density (HD) screw constructs show comparable and satisfactory radiographic and QOL for AIS patients. Furthermore, HD constructs had increased costs, operative time, and blood loss associated. However, a definitive conclusion cannot be made and more studies taking into account multiple additional variables are necessary to do so.