Charla R Fischer1, Lawrence G Lenke2, Keith H Bridwell3, Oheneba Boachie-Adjei4, Munish Gupta3, Yongjung J Kim2. 1. Hospital for Joint Diseases, NYU Langone Medical Center, New York, NY, USA. Electronic address: charla.fischer@nyumc.org. 2. Spine/Scoliosis Service, Columbia University, New York, NY, USA. 3. Orthopaedic Surgery, Washington University in St. Louis, MO, USA. 4. Spine/Scoliosis Service, Hospital for Special Surgery, New York, NY, USA.
Abstract
STUDY DESIGN: Retrospective cohort chart review. OBJECTIVE: To determine the optimal lowest instrumented vertebra (LIV) following posterior segmental spinal instrumented fusion (PSSIF) of thoracic adolescent idiopathic scoliosis (AIS) with LIV at L2 or above. SUMMARY OF BACKGROUND DATA: Few studies evaluate the optimal LIV based on rotation or center sacral vertical line (CSVL). METHODS: A radiographic assessment of 544 thoracic major AIS patients (average age 14.7 years) with minimum 2 years' follow-up (average 4.1 years) after PSSIF was performed. The LIV was divided by CSVL: stable vertebra 1 (SV-1) if the CSVL fell between the medial walls of the LIV pedicles; SV-2 if between stable vertebra 1 and 3; and SV-3 if the CSVL did not touch the LIV. LIV was divided by rotation into: neutral vertebra 0 (NV-0) if the LIV was at or distal to the neutral vertebra; NV-1 if one vertebra proximal to the NV; NV-2 if two vertebrae proximal; and NV-3 if three vertebrae proximal to the NV. RESULTS: The prevalence of adding-on (AO) or distal junctional kyphosis (DJK) at ultimate follow-up was 13.6%. Patients with AO or DJK had a higher rate of open triradiate cartilage, LIV not touching the CSVL, and more proximal to the NV (p < .05). Risk factors were SV-3 (39% vs. SV-2 14%, SV-1 9%, p < .05), NV-3 (35% vs. NV-2 9%, NV-1 6%, NV-0 12%, p = .000), open triradiate cartilage (43% vs. closed 13%, p < .05), lumbar C modifier (22% vs. B modifier 8%, A modifier 13%, p < .05), and Risser stage 0 (19% vs. 12% Risser 1-5, p < .05). CONCLUSION: The prevalence of AO or DJK at ultimate follow-up of PSSIF for AIS with LIV at L2 or above was 13.6%. Risk factors included the CSVL outside the LIV, LIV 3 or more proximal to the NV, open triradiate cartilage, lumbar C modifier, and Risser stage 0. LEVEL OF EVIDENCE: Level IV.
STUDY DESIGN: Retrospective cohort chart review. OBJECTIVE: To determine the optimal lowest instrumented vertebra (LIV) following posterior segmental spinal instrumented fusion (PSSIF) of thoracic adolescent idiopathic scoliosis (AIS) with LIV at L2 or above. SUMMARY OF BACKGROUND DATA: Few studies evaluate the optimal LIV based on rotation or center sacral vertical line (CSVL). METHODS: A radiographic assessment of 544 thoracic major AIS patients (average age 14.7 years) with minimum 2 years' follow-up (average 4.1 years) after PSSIF was performed. The LIV was divided by CSVL: stable vertebra 1 (SV-1) if the CSVL fell between the medial walls of the LIV pedicles; SV-2 if between stable vertebra 1 and 3; and SV-3 if the CSVL did not touch the LIV. LIV was divided by rotation into: neutral vertebra 0 (NV-0) if the LIV was at or distal to the neutral vertebra; NV-1 if one vertebra proximal to the NV; NV-2 if two vertebrae proximal; and NV-3 if three vertebrae proximal to the NV. RESULTS: The prevalence of adding-on (AO) or distal junctional kyphosis (DJK) at ultimate follow-up was 13.6%. Patients with AO or DJK had a higher rate of open triradiate cartilage, LIV not touching the CSVL, and more proximal to the NV (p < .05). Risk factors were SV-3 (39% vs. SV-2 14%, SV-1 9%, p < .05), NV-3 (35% vs. NV-2 9%, NV-1 6%, NV-0 12%, p = .000), open triradiate cartilage (43% vs. closed 13%, p < .05), lumbar C modifier (22% vs. B modifier 8%, A modifier 13%, p < .05), and Risser stage 0 (19% vs. 12% Risser 1-5, p < .05). CONCLUSION: The prevalence of AO or DJK at ultimate follow-up of PSSIF for AIS with LIV at L2 or above was 13.6%. Risk factors included the CSVL outside the LIV, LIV 3 or more proximal to the NV, open triradiate cartilage, lumbar C modifier, and Risser stage 0. LEVEL OF EVIDENCE: Level IV.
Authors: Brendon C Mitchell; David L Skaggs; Lawrence G Lenke; Tracey P Bastrom; Carrie E Bartley; Peter O Newton Journal: Spine Deform Date: 2021-07-03