Fenestrated Pedicle Screws in Spinal Oncology: Technique and Comparative Retrospective Analysis

Surgical Site Infection After Polymethyl Methacrylate Pedicle Screw Augmentation in Osteoporotic Spinal Vertebrae: A Series of 537 Cases

BACKGROUND

Retrospective observational study of prospectively collected outcomes.

OBJECTIVE

The use of transpedicular screws augmented with polymethyl methacrylate (PMMA) is an alternative for patients with osteoporotic vertebrae. To investigate whether using PMMA-augmented screws in patients undergoing elective instrumented spinal fusion (ISF) is correlated with an increased risk of infection and the long-term survival of these spinal implants after surgical site infection (SSI).

METHODS

We studied 537 consecutive patients who underwent ISF at some point within a 9-year period, involving a total of 2930 PMMA-augmented screws. Patients were classified into groups: (1) those whose infection was cured with irrigation, surgical debridement, and antibiotic treatment; (2) those whose infection was cured by hardware removal or replacement; and (3) those in whom treatment failed.

RESULTS

Twenty eight of the 537 patients (5.2%) developed SSI after ISF. An SSI developed after primary surgery in 19 patients (4.6%) and after revision surgery in 9 (7.25%). Eleven patients (39.3%) were infected with gram-positive bacteria, 7 (25%) with gram-negative bacteria, and 10 (35.7%) with multiple pathogens. By 2 years after surgery, infection had been cured in 23 patients (82.15%). Although there were no statistically significant differences in infection incidence between preoperative diagnoses (P = 0.178), the need to remove hardware for infection control was almost 80% lower in patients with degenerative disease. All screws were safely explanted while vertebral integrity was maintained. PMMA was not removed, and no recementing was done for new screws.

CONCLUSIONS

The success rate for treatment of deep infection after cemented spinal arthrodesis is high. Infection rate findings and the most commonly found pathogens do not differ between cemented and noncemented fusion. It does not appear that the use of PMMA in cementing vertebrae plays a pivotal role in the development of SSIs.

LEVEL OF EVIDENCE: 4

Comparing the efficacy and safety of cement-augmented fenestrated pedicle screws and conventional pedicle screw in surgery for spinal metastases: a retrospective comparative cohort study

Background

The incidence of cancer patients with bone metastasis is increasing annually. With the advancement of medical treatment for malignant tumors, the survival time of patients with spinal metastases is gradually being prolonged, and adjacent segment vertebral metastases often occur after conventional pedicle screw (CPS) surgery, leading to spinal instability, pain and nerve function injury again, with repeated symptoms. Combined pedicle screw fixation can maintain or reconstruct the spinal stability. This study aimed to investigate the efficacy and safety of cement-augmented fenestrated pedicle screws in the posterior approach for spinal metastases by comparing with CPS.

Methods

From January 2017 to August 2019, 52 patients with spinal metastases who underwent separation surgery and internal fixation via posterior approach were retrospectively enrolled. Cases were divided into the cement-augmented pedicle screw (CAPS) group (28 cases) and the CPS group (24 cases). The baseline data [age, gender, surgical sites, surgical segment, Tomita classification, Tomita score, Tokuhashi score, spinal instability neoplastic score (SINS)], surgical information, and local progression-free survival (PFS) time were compared between the two groups. Every patient was followed-up every 3 months with imaging examination. The visual analog scale (VAS) score and Frankel grade of the two groups were recorded before and 3 months after the operation were used to evaluate the efficacy. The operation time, the amount of intraoperative blood loss, the amount of bone cement injected in the pedicle screw group, and the complications of the surgery were recorded to evaluate the safety of CAPS.

Results

The baseline characteristics were comparable between the two group. Compared with the CPS group, the CAPS group showed significantly longer operation time (163±20 vs. 138±18 min, P<0.001) and lower VAS scores (2.93±1.33 vs. 4.17±1.34, P=0.002). Adjacent segment vertebral metastasis occurred in 10 cases (2 in the CAPS group and 8 in the CPS group, P=0.017). Internal implant failure occurred in 8 cases (1 in the CAPS group and 7 in the CPS group, P=0.011). Compared with the CPS group, the CAPS group had a significantly longer local PFS time (P<0.05).

Conclusions

CAPS could be a safe and effective choice in surgery for spinal metastases with the posterior approach.

Comparison of clinical effectiveness of fenestrated and conventional pedicle screws in patients undergoing spinal surgery: a systematic review and meta-analysis

INTRODUCTION

Pedicle screws are commonly used for spinal procedures for fusion stability, which is particularly important in osteoporotic patients, who are at an increased risk of requiring revision procedures.

AREAS COVERED

A systematic review and meta-analysis were conducted to compare clinical effectiveness of conventional pedicle screws (CPS) vs fenestrated pedicle screws (FPS) in patients undergoing spinal surgery. Primary outcomes included screw loosening, revision surgeries (involving an implant) and reoperations (not involving intervention on an implant) in patients treated with CPS vs FPS, sub-stratified by with and without osteoporosis. Secondary outcomes included changes in pain scores. Forty-eight studies with 8,302 patients were included, with 1,565 (19.18%) treated with FPS and 6,710 (80.82%) treated with CPS. FPS was associated with a lower risk of screw loosening (p = 0.001) vs CPS. In the general population, there was a non-significant trend of lower revision rate, but no difference in reoperation rate, between patients treated with FPS vs CPS. In osteoporotic patients, revision rates were significantly lower for FPS vs CPS (p = 0.009).

EXPERT OPINION

This review suggests that FPS are effective for surgical fixation and reduce rates of screw loosening, and in osteoporotic patients, revision surgeries, compared to CPS.