• Masahiro Kanayama, Daisuke Togawa, Tomoyuki Hashimoto, Keiichi Shigenobu, and Fumihiro Oha.
• Spine Center, Hakodate Central General Hospital, Hokkaido, Japan. mkanayama@aol.com
• J Spinal Disord Tech. 2009 Oct 1;22(7):463-7.

Study DesignA retrospective study.ObjectivesThis study aims to determine the prevalence and nature of adjacent-segment deterioration after posterior ligamentoplasty, posterolateral lumbar fusion (PLF) versus posterior lumbar interbody fusion (PLIF).Summary Of BackgroundMotion-preserving technologies including disc arthroplasty and ligamentoplasty were gaining interest to reduce the risk of adjacent-segment morbidity. However, few clinical studies have reported the prevalence of adjacent-segment disease in motion-preserving surgeries.MethodsTwo-hundred and eighteen consecutive patients who had undergone single-level posterior L4-L5 pedicle-screw-instrumented fusion or ligamentoplasty were reviewed at minimum 2-year follow-up. They were 91 males and 127 females with mean age of 62 years. Follow-up period was averaged 41 months and follow-up rate was 97.3%. There were 78 cases of PLIF, 75 of PLF, and 65 of ligamentoplasty. Demographics were not statistically different among the 3 groups. Prevalence of adjacent-segment morbidity (radiculopathy associated with newly developed pathologies at neighboring levels) and required additional surgery were investigated.ResultsPrevalence of adjacent-segment morbidity was 14.1% in PLIF, 13.3% in PLF, and 9.2% in ligamentoplasty; the time to represent symptom was averaged 25.2, 39.3, and 51.8 postoperative months, respectively. Additional surgeries for adjacent-segment pathologies were required for 7.6% in PLIF, 6.7% in PLF, and 1.5% in ligamentoplasty. Although all PLF cases needed only decompression surgeries, 66.7% of reoperations in the PLIF group required fusion owing to progression of adjacent-segment instability.ConclusionsPrevalence of adjacent-segment disease and reoperation rate seemed to be lower in ligamentoplasty than fusion surgeries, but the difference was not significant. Ligamentoplasty circumvented adjacent-segment disease for longer period than fusion surgeries. Although the rates of additional surgeries in PLIF and PLF were comparable, PLIF developed adjacent-level instability and required fusion surgery more frequently than PLF.

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