Incidence and Risk Factors Of Rod Fracture After Pedicle Subtraction Osteotomy Using Side-Tightening Pedicle Screw System — The International Society for the Study of the Lumbar Spine
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Incidence and Risk Factors Of Rod Fracture After Pedicle Subtraction Osteotomy Using Side-Tightening Pedicle Screw System (#1121)

Kee-Yong Ha 1 , Sang-Il Kim 2 , Young-Hoon Kim 2 , Hyung-Youl Park 3 , Sung-Cheol Yang 2
  1. Department of Orthopedic Surgery, Kyung Hee University Hospital at Gangdong, Seoul
  2. Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seocho-gu, Seoul, South Korea
  3. Orthopedic Surgery, Eunpyeong St. Mary's Hospital, The Catholic University of Korea, Seoul

Introduction: 

Rod fractures (RF) after pedicle subtraction osteotomy (PSO) for sagittal imbalance are not uncommon. Because previous reports analyzed cases using popular top-tightening pedicle screw system, there has not been a study reporting RF after PSO using side-tightening (ST) pedicle screw system. The purpose of this study was to investigate the incidence and risk factors of RF after a single-level lumbar PSO using a ST pedicle screw system.

 

Material and Methods: 

Fifty-seven consecutive patients who underwent a single-level lumbar PSO for their degenerative sagittal imbalance at a single institution were retrospectively reviewed. All surgeries were performed by a single surgeon using a ST pedicle screw system. Demographic, surgical, and radiographic data were analyzed to investigate the prevalence and risk factors for RF.

 

Results: 

Seven (12.3%) patients showed RF after PSO. Four patients had bilateral RFs and three patients had unilateral RF. The location of RF was at the PSO level in 6 of 7 patients. The ratio of adjacent interbody fusion was significantly different between the group with RF and the group without RF (16.7% versus 74.0%, P=0.004). Radiographic measurements revealed that preoperative segmental angle at the PSO vertebra (-6.1° ± 5.5° versus -1.7° ± 4.6°, P=0.049) and postsurgical change in LL (48.4° ± 8.8° versus 37.8° ± 11.9°, P=0.033) were significantly different between the two groups. Risk factor analysis using stepwise logistic regression analysis revealed that the absence of adjacent interbody cages (odds ratio [OR]: 0.011, 95% confidence interval [CI]: 0.000-0.390, p = 0.013) was a significant risk factor.

 

Discussion: 

The incidence of RF after a single-level lumbar PSO using ST pedicle screw system was 12.3%. Absence of adjacent interbody cage was a significant risk factor for RF in our series.

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