Factors affecting the postoperative progression of thoracic kyphosis in surgically treated adult patients with lumbar degenerative scoliosis.
METHODS
A retrospective case series of patients treated surgically for degenerative lumbar scoliosis (DLS).


OBJECTIVE
To determine incidence and risk factors of progressive global thoracic kyphosis (pGTK) after surgery for DLS.


BACKGROUND
Sagittal balance affects the surgical treatment of spinal deformity in adults. Little is known about the loss of sagittal balance due to pGTK, or about the risk factors for pGTK, after surgery for DLS.


METHODS
We reviewed records from a multicenter database of adults with DLS, treated with posterior spinal fusion. Inclusion required an age of 50 years or more at the time of surgery, an upper instrumented vertebra at T9 and below, more than 5 fused segments, and at least 2 years of follow-up. We included 73 patients with a mean age of 68.3 years (range, 51-77 yr) and a mean follow-up period of 3.6 years (range, 2-11 yr). Independent risk factors for pGTK were identified by logistic regression analysis.


RESULTS
Significant pGTK, defined as an increase in thoracic kyphosis of more than 10° from before surgery to the time of final follow-up, was observed in 41% of the patients. Loss of the sagittal vertical axis was larger in patients with pGTK than without (4.7 vs. 1.5 cm; P = 0.02). Risk analysis showed larger lumbar lordosis correction in patients with pGTK. Multivariate logistic regression analysis identified an age greater than 75 (odds ratio, 5.53; P = 0.02, 95% confidence interval [1.4-22.4]) and sacropelvic fusion (odds ratio = 2.66, P = 0.02, 95% confidence interval [1.5-11.1]) as independent risk factors for pGTK.


CONCLUSIONS
The pGTK incidence after surgery for DLS was 41%. Age, sacropelvic fusion, and a larger sagittal correction were identified as pGTK risk factors. Long-term follow-up will provide more data on the clinical impact of pGTK in elderly patients.


METHODS
3.
*Department of Orthopedic Surgery, National Center for Musculoskeletal Disorders, Murayama Medical Center, Tokyo, Japan †Department of Orthopedics, Keio University School of Medicine, Tokyo, Japan ‡Department of Orthopedics, Saiseikai Central Hospital, Tokyo, Japan §Department of Advanced Therapy for Spine and Spinal Cord Disorders, Keio University School of Medicine, Tokyo, Japan; and ¶KSRG, Tokyo, Japan.
Mitsuru
M
Yagi
Naobumi
N
Hosogane
Eijiro
E
Okada
Kota
K
Watanabe
Masafumi
M
Machida
Masaki
M
Tezuka
Morio
M
Matsumoto
Takashi
T
Asazuma
D000367:Age Factors; D000368:Aged; D001696:Biomechanical Phenomena; D016009:Chi-Square Distribution; D018450:Disease Progression; D005260:Female; D006801:Humans; D007564:Japan; D007738:Kyphosis / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D016015:Logistic Models; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D004856:Postural Balance; D011859:Radiography; D012189:Retrospective Studies; D012307:Risk Factors; D012600:Scoliosis / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D013123:Spinal Fusion / Q000009:adverse effects* / Q000295:instrumentation; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D013997:Time Factors; D016896:Treatment Outcome