410 Can a Universal Width Fit all? Exploring Optimal Dimensions for Cervical Disc Arthroplasty Implants

INTRODUCTION: Given the wide spectrum of implant widths, which are typically coupled to specific height and/or depth dimensions, and the desire to match native bony anatomy, as opposed to resecting/burring the bones to achieve implant-fit, there is need to clearly delineate subaxial cervical anatomy, especially at superior endplate (SEP). METHODS: Scans of the cervical spines from a convenience sample of 50 young, healthy patients (29 males, 21 females), aged 23-28 years (mean: 25.1±1.3 years), with mean BMI of 30.44 kg/m2, who underwent CT for negative trauma evaluations. The following measurements were estimated. RESULTS: The mean IUD at the posterior-third(A3), was the limiting width at all levels, which only increased from 11.3 ± 2 mm at C4 to 13.4 ± 2.9 mm at C7. The 3rd quartile of mean A3 distance were: C4–12.61 mm, C5–13.38 mm, C6–15.18 mm, C7–15.25 mm. A1 and A2 were both greater than 14 mm in majority of the subjects (C4–50%, C5–56%, C6–72%, C7–90%), whereas A1 and A2 were >17 mm (most contacted depth by all marketed implants) only in 2% at C4, 4% at C5, 16% at C6 and 44% at C7. While linear parameters differed significantly between the male and female sex, there was no statistically significant difference in mean A3 at any level (all p > 0.05). There also was no appreciable statistically significant difference between measured indices when grouped by BMI category. CONCLUSIONS: IUD increases from cephalad-to-caudad but reduces from anterior-to-posterior at each level. For vast majority, regardless of gender/BMI, the IUD is at least 14 mm, especially in most commonly CDA-treated disc spaces(C5-6, C6-7), suggesting that 14 mm could serve as "one-width" for all CDAs, especially since primary goal of the arthroplasty is to create proper width-fit of implant without bony resection.