527 - Correlation between Implant Motion and Patient Reported Outcome Measur...

General Session: MIS-3

Presented by: A.J. Berg - View Audio/Video Presentation (Members Only)

Author(s):

A.J. Berg(1,2), C.D. Jensen(3), S. Khan(1), R. Malgatil(1), G.R. Reddy(1), C. Bhatia(1), T. Friesem(1)

(1) North Tees and Hartlepool NHS Foundation Trust, Spinal Unit, Stockton on Tees, United Kingdom
(2) Pennine Acute Hospitals NHS Trust, Manchester, United Kingdom
(3) Northumbria Healthcare NHS Foundation Trust, Trauma and Orthopaedics, Northumberland, United Kingdom

Abstract

Introduction and Purpose: Motion preservation through the use of cervical disc arthroplasty (CDA) implants has been shown to produce equivalent or superior results to fusion. Some implants, however, do not perform as desired and some patients do not achieve the sought-after results. One would expect, however, that failure of an implant to move would not have negative impacts on outcome measures in the shorter term. We aim to assess if the clinical outcomes are similar in patients whose implants fail to maintain motion compared to those that continue to be mobile.

Methods: A retrospective review of the authors institution´s CDA database identified patients who had undergone single level CDA and had pre and post-operative flexion and extension radiographs of the cervical spine and outcome measures (Neck Disability Index (NDI), Visual Analogue Scale (VAS) for Neck and Arm pain and Hospital Anxiety and Depression Scales (HAD)) in the same time period. Radiographs were assessed by a single reviewer. The replaced segments ROM was measured using radiological software using the Harrison Posterior Tangent method. Patients were divided into two groups: mobile implant (ROM >2 degrees) or non-mobile implant (ROM < 2 degrees). The changes in outcomes scores from pre to post-operative were compared between the groups.

Results: Radiographic and clinical outcomes were available and assessed in 46 patients. In the group of 42 patients (91.3%) whose implants maintained motion, at an average follow-up of 66 weeks, NDI improved from 54 to 41.5, VAS Arms 6.3 to 4.1, VAS Neck 7.2 to 4.3, Depression 9.5 to 7.4 and Depression 10 to 9. The improvements achieved statistical significance in all parameters except Anxiety. Four out of the 46 implants (8.7%), which were initially mobile, were found to have < 2 degrees ROM at subsequent follow-up. In this group, at average follow-up of 43 weeks, NDI improved from 42.5 to 35, VAS Arm 7 to 4.5, VAS Neck 7 to 5.3, Depression 7.8 to 3.5 and Anxiety 7.3 to 6.5. None of the improvements achieved statistical significance with paired analysis. Results for comparison are shown in Table 1.

Conclusions: This study aimed to assess whether the clinical outcomes are similar in patients who have undergone CDA where the CDA implant fails to maintain motion compared to those that continue to move. 8.7% (n=4) of implants reviewed in this study did not maintain motion and while clinical outcomes did improve they did not achieve statistical significance. This is compared to the patients with mobile implants, whose outcomes not only improved but achieved statistical significance. The reasons for this difference are not clear but are likely multifactorial. The small sample size, differences in pre-operative scores and follow-up may have an influence. Further large RCTs are required for further evaluation and to draw stronger conclusions. This study can be utilised to ensure such studies are adequately powered.

Table 1: Pre and Post-Operative Outcome Scores