Umair Nadeem, Waqar Alam, Abdullah Shah, Atiq-uz Zaman, Amer Aziz.
Selection of lowest instrumented vertebra in the management of lenke 5 adolescent idiopathic scoliosis using pedicle screw instrumentation.
J Surg Pak Jan ;21(3):92-6.

Objective: To determine the lowest instrumented vertebra (LIV) in the management of Lenke 5 adolescent idiopathic scoliosis (AIS) patients using pedicle screw instrumentation. (PSI). Study design: A retrospective review. Place & Duration of study: Department of Orthopedics and Spine Surgery, Ghurki Trust Teaching Hospital Lahore, from January 2014 to April 2016. Methodology: Analysis of radiographic parameters of 32 patients was done. The patients were grouped according to the LIV level; Group I (fusion to L3, n=25) and Group II (fusion to L4, n=7). The Group I was further subdivided into IA (L3 crossed the mid-sacral line with rotation of less than grade II on bending films - n=14) and IIB (L3 did not cross the mid-sacral line or rotation was grade II or more on bending films n=11). All the patients in the Group II had the same location and rotation of L3 in bending films as that of patients in the group IB. Patients with lowest instrumented vertebral tilt (LIVT) of more than 10° or coronal balance of more than 15 mm, were considered to have unsatisfactory results. Results: LIVT was reduced from 20.8±6.3 to 5.5±2.9° in group IA and from 24.1±8.2° to 10.8±5.1° in group IB and from 26.7±4.6 to 6.9±5.2° in group II. A significantly less reduction was obtained in group IB (49.7%) as compared to group IA (88.4%) and group II (81.8%). Unsatisfactory results were obtained in 1 (7.1%) patient of group IA, in 7 (63.3%) patients of the group IB, and in 1 (12.5%) patient of group II which was found to be statistically significant. Conclusions: For the correction of thoracolumbar / lumbar AIS with pedicle screw instrumentation, L3 can be selected as the LIV instead of L4, thus saving one distal motion segment, when preoperatively L3 crosses the midsacral line with a rotation of less than Nash-Moe grade II in both the active bending radiographs, otherwise fusion has to be extended to L4.

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