Double-level cervical total disc replacement for adjacent segment disease: is it a useful treatment? Description of late onset heterotopic ossification and review of the literature.

We report a rare case of double-level adjacent segment disease (ASD), occurring ten years later an anterior cervical discectomy (ACD) without fusion, treated by cervical arthroplasty, highlighting the outcome at long-term follow-up and focusing on heterotopic ossification. In 1995 a 25-year-old man satisfactorily underwent ACD at C4/C5. At that time MRI also showed signs of degenerative disc disease (DDD) at C3/C4 and C5/C6. Ten years later, a new MRI scan showed a large C3/C4 and a smaller C5/C6 soft disc hernia together with spondylotic changes at the level above and below the site of the first surgery. At C4/C5 imaging revealed a kyphotic stable "pseudoarthrosis" with anterior bridging osteophyte. The patient underwent double-level arthroplasty with ProDisc-C. Clinical and radiological outcome was satisfactory. 3 and 5 years after surgery, X-rays and CT scan documented the progressive development of heterotopic ossification, with gradual reduction of range of motion. A late onset heterotopic ossification can neutralize the theoretical advantages of cervical arthroplasty, which should be considered an effective surgical option only in selected cases. ACDF and restoration of normal lordosis can be a viable alternative in cervical revision surgery, as motion preservation can not be always mantained for a long time.

Anterior, extracanalar, cervical spine osteochondroma associated with DISH: description of a very rare tumor causing bilateral vocal cord paralysis, laryngeal compression and dysphagia. Case report and review of the literature.

INTRODUCTION: Osteochondromas are common benign bone tumors, rarely involving the spine. BACKGROUND: Osteochondroma account for about 35% of bone benign tumors and 9% of all bone tumors. Spinal involvement is described in 1%-4% of cases and their origin from the anterior surface of cervical vertebral bodies is exceedingly rare. AIM: We describe the rare case of an osteochondroma arising from the anterior surface of the C4 and C5 vertebral bodies, and not involving the spinal canal, in a 68-year-old male patient suffering from Diffuse Idiopathic Skeletal Hyperostosis (DISH). MATERIALS AND METHODS: The patient presented with acute onset of respiratory distress due to laryngeal compression exerted by the lesion, dysphagia and paralysis of left vocal cord. Imaging revealed the unusual lesion compressing and dislocating the air ways. An anterior approach to cervical spine was performed to remove the tumor. RESULTS: Postoperatively, the patient sustained a progressive improvement of respiratory function and recovery of the vocal cord paralysis. DISCUSSION: We believe that this case holds some interesting peculiarities: firstly, the anterior location of a cervical osteochondroma could be considered exceptional; yet, the resulting clinical picture should be remembered for differential diagnosis. Secondly, we hypothesized a possible correlation between the tumorigenesis of osteochondroma and the co-existence of DISH. Indeed, the abnormal bone turnover in cervical segments due to DISH could explain the unusual occurrence of osteochondromas in adult age. CONCLUSIONS: The occurrence of an osteochondroma should be considered in patients suffering from DISH and harbouring large osteophytes.