Regression of anterior cervical disc-osteophyte complex following artificial disc replacement – A radiological phenomenon

Purpose Cervical disc arthroplasty (CDA) has gained popularity as a suitable alternative to ACDF for treatment of anterior cervical compressive pathologies. Regression of anterior cervical disc osteophyte complex after CDA is a less commonly recognized and understood radiological finding, one which was previously only described following fusion. Our aim is to describe the regression of anterior cervical disc osteophyte complex following CDA, and discuss its potential clinical significance. Methods Baseline characteristics, clinical presentation, perioperative details, and postoperative details were collected of patients who underwent CDA with a minimum of 2-year follow up. Presence of implant subsidence, peri-implant fractures, and heterotopic ossification were also recorded. Radiological parameters including pre and postoperative global cervical alignment, segmental range of motion, protrusion of cervical disc-osteophyte complex at each vertebral level. Results 50 patients (122 levels) were analyzed. Regression of anterior cervical disc osteophytes was observed in 92 levels (75%) at 3-month postoperatively, 75 levels (61%) at 1-year postoperatively, and 40 levels (33%) at 2-year postoperatively. Mean osteophyte size significantly decreased from immediate postoperative period up to 1-year follow-up ( p  < 0.005), with no significant difference in osteophyte size between 1 and 2-year follow-up. Range of motion of C2-7 and operated functional spinal unit improved throughout all 3 follow-up timepoints. Heterotopic ossification was observed up to 35 levels (28%) at 2-year follow-up. Conclusion Regression of anterior cervical disc-osteophyte complex following CDA suggests stress distribution and restoration of movement in the cervical spine, and may be a useful predictor of satisfactory functional and radiological outcomes.