title: Determination of the distal fusion level in the management of thoracolumbar and lumbar adolescent idiopathic scoliosis using pedicle screw instrumentation.
abstract: METHODS
  A retrospective study.
  
  
  OBJECTIVE
  To determine the exact distal fusion level in the management of thoracolumbar/lumbar adolescent idiopathic scoliosis (TL/L AIS) using pedicle screw instrumentation (PSI).
  
  
  BACKGROUND
  The selection of distal fusion level remains controversial in TL/L AIS.
  
  
  METHODS
  Radiographic parameters of 66 TL/L AIS patients were analyzed. The patients were grouped according to the distal fusion level; L3 group (fusion to L3, n=58) and L4 group (fusion to L4, n=8). The L3 group was subdivided into L3A (L3 crosses the mid-sacral line with rotation of less than grade II, n=33) and L3B (L3 does not cross the mid-sacral line or rotation is grade II or more, n=25) based on both bending radiographs. All of the patients in the L4 group had the same location and rotation of L3 in bending films as that of patients in the L3B group. An unsatisfactory result was defined as a lowest instrumented vertebral tilt (LIVT) of more than 10° or coronal balance of more than 15 mm.
  
  
  RESULTS
  Among the 3 groups, there was a significantly lesser correction in the TL/L curve and LIVT in the L3B group. Unsatisfactory results were obtained in 3 patients (9.1%) of the L3A group, in 15 patients (68.2%) of the L3B group, and in 1 patient (12.5%) of the L4 group with a significant difference.
  
  
  CONCLUSIONS
  In TL/L AIS treatment with PSI, the curve can be fused to L3 with favorable radiographic outcomes when L3 crosses the mid-sacral line with rotation of less than grade II in bending films. Otherwise, fusion has to be extended to L4.
authors.affiliation: Department of Orthopaedics, Haeundae Paik Hospital, Inje University College of Medicine, Busan, Korea.
authors.forename: Sung-Soo
authors.initials: SS
authors.lastname: Kim
authors.affiliation: Seoul Spine Institute, Sanggye Paik Hospital, Inje University College of Medicine, Seoul, Korea.
authors.forename: Dong-Ju
authors.initials: DJ
authors.lastname: Lim
authors.affiliation: Seoul Spine Institute, Sanggye Paik Hospital, Inje University College of Medicine, Seoul, Korea.
authors.forename: Jin-Hyok
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Seoul Spine Institute, Sanggye Paik Hospital, Inje University College of Medicine, Seoul, Korea.
authors.forename: Jong-Woo
authors.initials: JW
authors.lastname: Kim
authors.affiliation: Seoul Spine Institute, Sanggye Paik Hospital, Inje University College of Medicine, Seoul, Korea.
authors.forename: Kyu-Sub
authors.initials: KS
authors.lastname: Um
authors.affiliation: Seoul Spine Institute, Sanggye Paik Hospital, Inje University College of Medicine, Seoul, Korea.
authors.forename: Soo-Hyung
authors.initials: SH
authors.lastname: Ahn
authors.affiliation: Seoul Spine Institute, Sanggye Paik Hospital, Inje University College of Medicine, Seoul, Korea.
authors.forename: Se-Il
authors.initials: SI
authors.lastname: Suk
keywords: Adolescent; Instrumentation; Scoliosis; Spinal fusion