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Researchers classify ossification based on morphology after disc arthroplasty
Researchers who analyzed various classifications of heterotopic ossification after cervical disc arthroplasty concluded that type I heterotopic ossification occurred in the posterior disc space, while type II and type III heterotopic ossification occurred mainly and completely in the anterior disc space, respectively.
“It is suggested that a cervical arthroplasty should be selected in terms of the implant level, hybrid conditions on the upper adjacent segment, disc design vulnerable to the pseudotranslation, the presence of preoperative ossification and fitting implants to end plates to reduce the development of [heterotopic ossification] HO,” Yong Jun Jin, MD, and colleagues wrote in the study abstract.
The researchers used Bryan (Medtronic Sofamor Danek; Memphis, Tenn.), PCM (Cervitech; Rockaway, N.J.), and Prestige LP (Medtronic Sofamor Danek) implants in 81 patients who underwent 95 cervical arthroplasties, according to the abstract. Classification of HO was divided into three types based on end plate (type I), traction spur (type II) and teardrop (type III) morphologies.
They found that the Bryan implant had a 49% incidence of HO, while the PCM had 80% and the Prestige had 60%. Specifically, type I HO was only found in posterosuperior disc space and was significantly related to male gender, the PCM implant, preoperative ossification and ossification in the ligamentum nuchae as well as a well-fitting and less lordotic segmental angle, according to the abstract.
The majority of type II HO was found in the anterior disc space, with some growth in the posterosuperior disc space – risk factors for this HO type included “implantation in the upper cervical level and hybrid implantation with cage or artificial disc on the upper adjacent level,” the researchers wrote.
While type III HO developed only in the anterior disc space, the researchers noted the PCM implant had the highest incidence of type II and type III HO over other implants.
Disclosure: The authors have no relevant financial disclosures.