Clinical Significance of the Radiolucent Zone Around the Pedicle Screws in the Lumbar Degenerative Disease.
10.4184/jkss.2009.16.3.202
- Author:
Jong Ill KWAK
1
;
Kyu Yeol LEE
;
Hyeon Jun KIM
;
Sang Kyu SUN
Author Information
1. Department of Orthopedic Surgery, College of Medicine, Dong-A University, Busan, Korea. gylee@dau.ac.kr
- Publication Type:Original Article
- Keywords:
Degenerative lumbar disease;
Pedicle screw;
Radiolucent zone;
Pseudoarthrosis
- MeSH:
Follow-Up Studies;
Humans;
Pseudarthrosis;
Reoperation;
Retrospective Studies
- From:Journal of Korean Society of Spine Surgery
2009;16(3):202-209
- CountryRepublic of Korea
- Language:Korean
-
Abstract:
STUDY DESIGN: A retrospective study. OBJECTIVE: To analyze the clinical significance of the radiolucent zones surrounding pedicle screws. SUMMARY OF LITERATURE REVIEW: Clear zones have been suggested in pseudoarthrosis and a loss of fixation. However, few reports have clearly described the long-term course and clinical significance of clear zones. MATERIALS AND METHODS: The clear zones were evaluated in 399 patients with pedicle screw fixation after 6 months, 1 year, 2 years and 3 years. The patient was considered to be clear zone positive when 1 mm or greater circumferential lucency was confirmed around a screw on film from 2 or more directions. The time-course of the clear zones was examined with regard to age, number of levels fused, bone union, fusion method and reoperation. RESULTS: After 6 months, clear zones were observed in 124 patients (31.1%) but the clear zone-positive rate decreased with time. Clear zones were observed in 89 patients(22.3%), 44 patients(11.0%) and 41 patients(10.3%) after 1 year, 2 years and 3 years, respectively. No new clear zones had developed after 6 months. At the final follow-up, pseudoarthrosis was observed in 12 patients(3.0%). Among them, 11 were clear zone-positive and 1 was clear zone-negative. There was a statistically significant relationship between the clear zone-positive rate and multi-levels, older age and nonunion during following up. In addition, there was a relatively lower clear zone-positive rate in posterolateral fusion combined with posterior lumbar interbody fusion than only posterolateral fusion. However, the difference between them was not statistically significant. CONCLUSION: The presence of clear zones does not always mean pseudoarthrosis but clear zones persisting for more than 2 years after surgery have a higher rate of pseudoarthrosis.
