Percutaneous vertebral augmentation assisted by PEEK implant in painful osteolytic vertebral metastasis involving the vertebral wall: experience on 40 patients.

Background: Vertebral metastases are associated with significant pain, disability, and morbidity. Open surgery for fracture stabilization is often inappropriate in this cancer population due to a poor risk-benefit profile, particularly if life expectancy is short. Vertebroplasty and kyphoplasty are appealing adjunctive procedures in patients with malignancy for alleviation of intractable pain. However, these patients have a higher risk of serious complications, notably cement extravasation.

Study Design: We prospectively evaluated clinical results of polyetheretherketone (PEEK) implant (Kiva) assisted vertebroplasty performed in malignant painful osteolytic lesions at risk for cement extravasation due to vertebral wall involvement.

Setting: Department of Interventional Radiology, Institute for Cancer Research and Treatment, Candiolo, Turin, Italy

Methods: Forty patients (22 women; mean age 66.8 ± 12.4), suffering from a painful spine malignancy with vertebral wall involvement not responding to conventional therapies and without surgical indications, underwent vertebral augmentation with Kiva intravertebral implant for pain palliation. The procedure was performed with moderate sedation and local anesthesia under combined digital fluoroscopy and computed tomography guidance. After the coil-shaped PEEK implant was deployed within the vertebral lesion, bone cement was injected under continuous digital fluoroscopic control. Patients were discharged from the hospital the next procedural day. The Visual Analog Scale (VAS) for pain, Oswestry Disability Index (ODI), analgesic requirement, and use of external brace support were evaluated to determine efficacy. The primary end-point was safety and efficacy at one month after the procedure. However, all the patients were scheduled to be followed-up at month 3, 6, and every 6 months thereafter. Follow-up was prospectively evaluated in all patients after Kiva with clinical interviews. The Institution's Internal Review Board approved this study.

Results: Median pre-treatment VAS of 10 (range 6 - 10) significantly (P < 0.001) dropped to one (range 0 - 3), with all patients achieving a clinically relevant benefit on pain at one month. Differences in pre- and post-treatment analgesic therapy were significant (P < 0.001). All patients no longer use an external brace after Kiva. In 7 out of 43 (16.3%) treated vertebrae a bone cement leakage was detected.

Limitations: This is a not randomized study. Participants were limited to 40 patients.

Conclusion: The Kiva System potentially represents a novel and effective minimally invasive treatment option for patients suffering from severe pain due to osteolytic vertebral metastases.