Fenestrated pedicle screws for cement-augmented purchase in patients with bone softening: a review of 21 cases

Abstract

BackgroundThis prospective mixed cohort study was designed to evaluate the middle- to long-term purchase of cement-augmented pedicular screws in patients with poor bone quality. The growing number of surgical procedures performed in the spine has highlighted the problem of screws loosening in patients with poor bone stock due to osteoporosis and/or tumors. Different methods of increasing screw purchase have been reported in the literature, including polymethylmethacrylate (PMMA) augmentation.Materials and methodsFrom September 2006 to April 2008, 21 patients with a poor bone stock condition due to osteoporosis or tumor underwent posterior stabilization by fenestrated pedicle screws and PMMA augmentation. Pain improvement and long-term clinical outcome were assessed by visual analogue scale (VAS) score and SF-36 health survey (SF-36) questionnaire. Implant stability was evaluated by plain radiography and CT scans performed three days after surgery and every three months thereafter. After the first 12 months, radiologic controls were taken once a year in all surviving patients. Complications were evaluated in all cases.ResultsAll patients were clinically and radiographically followed up for a mean of 36 months. VAS scores and SF-36 questionnaires showed a statistically significant reduction in pain and improvement in the quality of life. No radiological loosening or pulling out of screws was observed. In two cases, cement leakage occurred intraoperatively: one patient who suffered from a transitory nerve root palsy improved spontaneously, while the surgeon immediately removed the excess cement before setting in the other case. In three cases, the post-op CT scan revealed a small amount of cement in the canal without clinical relevance.ConclusionsFenestrated screws for cement augmentation provided effective and lasting purchase in patients with poor bone quality due to osteoporosis or tumors. No case of loosening was recorded after a mean follow-up of 36 months. The only clinical complication strictly related to PMMA screw augmentation did not require further surgery.

Cement leakage in pedicle screw augmentation: a prospective analysis of 98 patients and 474 augmented pedicle screws

“…19 Furthermore, there is a positive correlation between the applied cement volume and the likelihood of cement leakage. 2,45 The cement volume should be kept to the smallest volume needed and should not exceed 2.8 ml per pedicle screw. 17 High application pressure, liquidity of the cement, and special anatomical features of the perivertebral venous system are conducive to cement leakage.…”

A novel injectable calcium phosphate-based nanocomposite for the augmentation of cannulated pedicle-screw fixation

“…This complex can promote the mechanical stability of screw fixation, improve fatigue resistance, and also decrease the risk of cement leakage. [11][12][13] To date, all the clinical cases and most of the research have used only PMMA for the augmentation of cannulated screws, 14,15 largely due to the high fluidity and injectability of PMMA, which can easily be fed through a cannula of a typical diameter of 1.6 mm and outlet holes of small diameter -around 0.9 mm. Other types of bioabsorbable cements are comparatively less reported for applications in cannulated pedicle screws.…”

Polymethylmethacrylate (PMMA) Augmentation Of A Cannulated And Fenestrated Pedicle Screw Fixation For Stabilization Of The Lumbar Degenerative Disease Accompanied With Osteoporosis

“…Therefore, to improve osteoporosis bone -screw interface is the key to solving these problems.Bone -screw interface stability in general and BMD, screw geometry, screw fixation technologies. There are many methods currently used clinically to improve the stability of the pedicle screw, the side hole of the hollow bone cement augmentation of pedicle screw is a reliable method of [5], so that after the bone cement augmentation of pedicle screw -the bone-cement interface and bone cement -bone interface connection strength greatly enhanced bone cement in vertebral cancellous bone diffusion, increase the contact surface with the bone, the screw has been enhanced stability [6,7].Hollow side pedicle screw holes in recent years developed a new type of pedicle screws, and its design features are hollow screw tip with side holes, making the bone cement through this pathway diffuse into the surrounding bone screws through screws and bone cement anchors, bone cement and bone surrounding the screw anchors fixed to enhance capacity. Therefore, the authors used cement -reinforced hollow side to enhance the stability of the pedicle screw holes and screw holding power.…”

“…So be firm pedicle screw in osteoporosis patients is very difficult [1]. In order to improve osteoporosis pedicle screw fixation strength , we used poly (methyl methacrylate) (Polymethylmethacrylate, PMMA) bone cement augmentation of pedicle screws to the side hole of the hollow increases in osteoporotic vertebral pedicle screw the gripping force [2 ] . Experiments show that this new type of pedicle screws has a stronger biomechanical property [3].…”