1580. Fusion and Quality of Life using Interspinous Process Clamp for the Treatment of Delayed Lumbar Fusion: a Retrospective Cohort Study

Authors: Richard Floyd Cook, DO; Doris Tong, MD; Matthew Bahoura, BA; Teck-Mun Soo, MD; Peter Bono, DO (Farmington Hills, MI)


Spacer-devices have been used as stand-alone devices and to
augment lumbar decompression. We sought to demonstrate that
interspinous process clamps (ISP) are effective in rescuing
delayed fusions in order to avoid lumbar pseudarthrosis.


We retrospectively analyzed prospectively collected data of
consecutive patients who underwent revision lumbar surgery using
ISP for 1-2 levels delayed lumbar fusion by a single surgeon at two
hospitals between February 2014 and December 2017. Patients
were included if delayed fusion was diagnosed within 18 months of
their prior surgery. Patients were followed by XR/CT for at least 3
months and by clinic visit/phone interview for at least 6 months
after the ISP surgery. We collected data for patient demographics
and surgical characteristics. The primary outcomes are interbody
fusion as evaluated by the Suk criteria and posterior interlaminar
fusion as evaluated by the modified Christensen criteria. Our
secondary outcomes were Quality-of-life (QoL) outcomes as
evaluated by VAS and SF-12. Descriptive statistics were used.


Twenty-two patients were included in the study. All 22 patients
underwent XR and 18 patients underwent CT evaluation. QoL
outcomes were evaluated in all 22 patients. The mean age of the
delayed fusion before ISP surgery was 0.71±0.24 year. Patient
demographics were presented in table 1. Surgical characteristics
were presented in table 2. The mean postoperative imaging
interval was 10±8.5 months. Among the 25 interspaces, the rate
for solid interbody fusion was 68%, probable interbody fusion was
32%. Among the 22 patients, the rate for solid posterior fusion was
100% (table 3). QoL data collected with at least 6 months’ followup
showed satisfactory results (table 4).


ISP achieved satisfactory interbody and posterior fusion as a
rescue technique in patients suffering from delayed fusion. The
study is limited by the retrospective design and low incidence of
delayed fusion.