Postoperative segmental hypermobility after cervical arthroplasty: A possible pathomechanism for outcome failure.

We present a 41-year-old man who underwent a cervical discarthroplasty (CDA) C5-6 procedure with an increase of the segmental range of motion from 2.8° to 6.9° and an increase in disc height from 5.8mm preoperatively to 10.4mm postoperatively with an unfavorable long-term clinical outcome. Both anterior cervical discectomy with fusion (ACDF), as well as CDA have been proven to be successful procedures in the management of cervical radiculopathy with good to excellent outcomes and low complication rates. The rationale for CDA over ACDF highlights the preservation of segmental motion and reduction of the incidence of adjacent segment disease. This case report suggests that a hypermobility syndrome and also an overcorrection of the cervical range of motion may be responsible for an unfavorable outcome after CDA.