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J Orthop Surg Res. 2015 Mar 26;10:39. doi: 10.1186/s13018-015-0186-8.

Does pre-existing L5-S1 degeneration affect outcomes after isolated L4-5 fusion for spondylolisthesis?

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Department of Neurosurgery, The Leon Wiltse Memorial Hospital, Anyang, Korea.
Department of Neurosurgery, Prime Hospital, Busan, Korea.
Department of Neurosurgery, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo Daero Seocho-gu, 137-701, Seoul, Korea.
Department of Neurosurgery, Wooridul Spine Hospital, Seoul, Korea.



Concerns have been raised regarding residual symptoms of caudal segment (L5-S1) degeneration that may affect clinical outcomes or require additional surgery after isolated L4-5 fusion, especially if there is pre-existing L5-S1 degeneration. This study aimed to evaluate the L5-S1 segment after minimally invasive lumbar interbody fusion at the L4-5 segment, as well as the influence of pre-existing L5-S1 degeneration on radiologic and clinical outcomes.


This retrospective study evaluated patients with isthmic spondylolisthesis and degenerative spondylolisthesis who underwent mini-open anterior lumbar interbody fusion with percutaneous pedicle screw fixation (PSF) or minimally invasive transforaminal interbody fusion with PSF at the L4-5 segment. The minimum follow-up period was 7 years, and radiographic evaluations were conducted via magnetic resonance imaging, computed tomography, and plain radiography at the 5-year follow-up. Clinical outcomes were assessed using the Visual Analog Score, Oswestry Disability Index, and surgical satisfaction rate. Patients were divided into two groups, those with and without pre-existing L5-S1 degeneration, and their final outcomes and incidence of radiographic and clinical adjacent segment disease (ASD) were compared.


Among 70 patients who underwent the procedures at our institution, 12 (17.1%) were lost to follow-up. Therefore, this study evaluated 58 patients, with a mean follow-up period of 9.4 ± 2.1 years. Among these patients, 22 patients had pre-existing L5-S1 degeneration, while 36 patients did not have pre-existing L5-S1 segmental degeneration. There were no significant differences in the clinical outcomes at the final follow-up when the two groups were compared. However, radiographic ASD at L5-S1 occurred in seven patients (12.1%), clinical ASD at L5-S1 occurred in three patients (5.2%), and one patient (1.7%) required surgery. In the group with pre-existing degeneration, L5-S1 degeneration was radiographically accelerated in four patients (18.2%) and clinical ASD developed in one patient (4.5%). In the group without pre-existing degeneration, L5-S1 degeneration was radiographically accelerated in three patients (8.3%) and clinical ASD developed in two patients (5.7%). There were no differences in the incidence of ASD when we compared the two groups.


Pre-existing L5-S1 degeneration does not affect clinical and radiographical outcomes after isolated L4-5 fusion.

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