instrumentation_pull_out [Neurosurgery Wiki]

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The use of [[pedicle screw]]s in low [[bone]] quality patients implicates risks of secondary implant loosening for grip lack. In fact, the result is a reduced [[mechanical stability]] at bone-screw interface and consequently an increased chance of [[pullout]] and hardware failure. [[Augmentation]] techniques have been described for many years and fenestrated screws that allow [[cement]] injection is one of them. 

In a retrospective [[observational]] study of patients treated with [[polymethylmethacrylate]]- (PMMA) augmented fenestrated screws. Indications for posterior instrumentation were traumatic [[fracture]] in osteoporotic spine, oncological disease, post-traumatic deformity, degenerative disease, revision surgery and sickle cell disease fractures. Implant stability was evaluated with X-Rays and CT scan performed 3 days after surgery and every 3 months during the follow-up. Accuracy of screw placement was evaluated with Heary classification. Fifty-three surgical treatments in 52 patients were performed and 247 PMMA augmented fenestrated screws were placed. According to the Heary classification, 96.21% resulted Grade I, 1.8% Grade II, 2% Grade IV. A total of 17 complications occurred. Fenestrated screw augmentation should be performed in selected patients in whom the bone quality is insufficient to guarantee implant stability. These screws may result useful in complex cases as revision surgeries, osteoporosis and tumour affections where bone quality is highly compromised
((Ghermandi R, Pipola V, Colangeli S, Parchi P, Andreani L, Capanna R,
Gasbarrini A. Polymethylmethacrylate-augmented fenestreted pedicle-screw fixation
in low bone quality patients: a case series and literature review. J Biol Regul
Homeost Agents. 2018 Nov-Dec;32(6 Suppl. 1):71-76. PubMed PMID: 30644285.
)).