Can Polyether Ether Ketone Dethrone Titanium as the Choice Implant Material for Metastatic Spine Tumor Surgery?

Instrumentation during metastatic spine tumor surgery (MSTS) provides stability to the spinal column in patients with pathologic fracture or iatrogenic instability produced while undergoing extensive decompression. Titanium is the current implant material of choice in MSTS. However, it hinders radiotherapy planning and generates artifacts, with magnetic resonance imaging and computed tomography scans used for postoperative evaluation of tumor recurrence and/or complications. The high modulus of elasticity of titanium (110 GPa) results in stress shielding, which may lead to construct failure at the bone-implant interface. Polyether ether ketone (PEEK), a thermoplastic polymer, is an emerging alternative to titanium for use in MSTS. The modulus of elasticity of PEEK (3.6 GPa) is close to that of cortical bone (17-21 GPa), resulting in minimal stress shielding. Its radiolucent and nonmetallic properties cause minimal interference with magnetic resonance imaging and computed tomography scans. PEEK also causes low-dose perturbation for radiotherapy planning. However, PEEK has reduced bioactivity with bone and lacks sufficient rigidity to be used as rods in MSTS. The reduced bioactivity of PEEK may be addressed by 1) surface modification (introducing porosity or bioactive coating with hydroxyapatite [HA] or titanium) and 2) forming composites with HA/titanium. The mechanical properties of PEEK may be improved by forming composites with HA or carbon fiber. Despite these modifications, all PEEK and PEEK-based implants are difficult to handle and contour intraoperatively. Our review provides a comprehensive overview of PEEK and modified PEEK implants, with a description of their properties and limitations, potentially serving as a basis for their future development and use in MSTS.

Postoperative Single-shot Epidural Fentanyl and Bupivacaine for Postoperative Analgesia After Lumbar Decompression: A Prospective, Double-blind Randomized Study.

STUDY DESIGN: Randomized clinical trial. OBJECTIVE: To evaluate the efficacy of the postoperative single-shot bolus of epidural Fentanyl and Bupivicaine in providing pain relief postlumbar decompression surgery. SUMMARY OF BACKGROUND DATA: Despite lumbar decompression's success in alleviating symptoms of sciatica, radiculopathy, and neurogenic claudication, transient back and buttock pain has been a common complaint postoperatively. Providing good postoperative pain alleviation predicts patient's quality of recovery. METHODS: We performed a randomized, double-blinded, clinical trial. Forty-five patients scheduled for lumbar decompression for a year's period who were randomly assigned to receive a postoperative bolus of 10-mL solution of 50 mcg of Fentanyl, 0.125% Bupivacaine, and 0.9% saline solution via an intraoperatively placed epidural catheter immediately after wound closure, before dressing application. Facial pain scale scores (from 0 to 10) were measured at three time points after surgery (fully awake at recovery room, transfer to ward, first postoperative day). Postoperative need for oral analgesics, time to independent ambulation, associated adverse events, and time to hospital discharge were also evaluated. RESULTS: Pain scores were noted to be significantly lower at all time points in the epidural group (P < 0.001). In turn, they also received less on-demand oral pain medications than those in the control group (P = 0.000). The mean time to ambulation was 0.09 days in the epidural group and 0.91 days in the decompression-alone group (P = 0.000). Criteria for hospital discharge were usually met on Day 0 in the epidural and Day 1 in the control group (P = 0.000). Within the study period, only one infection was noted in the epidural group which necessitated additional lumbar spine surgery (4.3%). No adverse events or complications related to Fentanyl use were observed. CONCLUSIONS: A postoperative bolus of Fentanyl and Bupivacaine is effective in reducing early postoperative pain without the related complications of opiod administration. LEVEL OF EVIDENCE: 2.