556 - Radiological and Clinical Outcomes after Insertion of an Interspinous...

#556 Radiological and Clinical Outcomes after Insertion of an Interspinous Spacer Device – A Retrospective Cohort Analysis of 74 Patients

Posterior Dynamic Pedicular Stabilization

Poster Presented by: C.G. Nita


C.G. Nita (1)
A.J. Berg (1)
C.D. Jensen (1)
P. Raju (1)
T. Ali (1)
G.R. Reddy (1)
T. Friesem (1)

(1) North Tees and Hartlepool NHS Foundation Trust, Orthopaedics, Stockton-on-Tees, United Kingdom


Introduction and Aim: Interspinous devices can be of benefit in treating spinal stenosis and neural compression. They increase the interspinous distance and posterior disc height which tensions the posterior ligamentous structures, resulting in an increased canal cross-sectional area and increased foraminal dimensions. We examine the radiological changes and clinical outcomes of 74 patients following insertion of the InswingÒ interspinous devices.

Method: Seventy-four patients with one and two level InSwingÒ interspinous implants inserted from 2010 to 2012 were reviewed (88 implants). Gender ratio was (M:F) 1.2:1. Standardized EOSÒ Lumbar spine radiographs were taken preoperatively, postoperatively, at 3 months, and at 1 year, and were examined by a senior radiologist. The posterior disc height and foraminal dimensions (anterior-posterior/superior-inferior) of each operated level were measured. Each patient completed preoperative and postoperative questionnaires including Oswestry Disability Index, VAS score and SF36 PCS and SF36 MCS. According to main clinical symptom preoperative, patients were separated in two groups: Back pain lot 58% and Leg pain lot 42%.

Results: Results are given as a percentage of implants with increased dimensions compared to pre-operative radiographs. Immediately postoperative increase: posterior disc height 89.23%; foraminal height 70.76%; foraminal width 64.61%. Three months: posterior disc height 56.66%; foraminal height 50%; foraminal width 50%. One year: posterior disc height 28.04%, foraminal height 30.48% and foraminal width 36.58%.

There was a marked improvement in all the clinical outcome measures at the early post-operative follow up stage, and unlike the radiographic measurements this improvement was sustained past the 1 year follow up end point.

Conclusions: InSWingÒ interspinous devices have been shown to increase the posterior disc height and foraminal dimensions immediately post-operative and these changes persist in about one third of the cases at 1 year follow up. This rapid effect would be of clinical benefit when treating neural compression caused by acute lumbar disc prolapse. Clinical outcome scores were also improved following interspinous spacer insertion, however, this improvement was sustained and progressive, as opposed to the radiological improvements which seemed to be short-lived in the majority of patients. Further prospective clinical studies are planned to correlate clinical and radiological findings for a longer follow up period.