Bony fusion through an empty cervical disc interspace implant

Area of Science:

• Spinal surgery
• Orthopedic implants
• Bone fusion biology

Background:

• Cervical intervertebral cages often feature holes for bone grafting to promote fusion.
• The necessity of filling these holes and assessing fusion, particularly with titanium implants, remains debated.
• Current evaluation of bony fusion is challenging and often limited to problematic cases.

Observation:

• A case of recurrent issues years after anterior cervical discectomy with a titanium cage, without bone grafting, was analyzed.
• The patient underwent revision surgery, and the cage contents were examined histologically.
• Radiographic assessment indicated successful fusion prior to revision.

Findings:

• Histological examination revealed solid bone formation within the hollow intervertebral cage.
• This demonstrates that complete bony bridging can occur through an empty implant.

Implications:

• The capacity for spontaneous bone formation within empty implants challenges current fusion assessment protocols.
• This finding has significant implications for the ongoing discussion regarding bone substitutes and bone graft alternatives in cervical fusion.
• Future research should consider the potential for fusion in empty cages when evaluating treatment outcomes.