Surgical treatment of degenerative and traumatic spinal diseases with expandable screws in patients with osteoporosis: 2-year follow-up clinical study

Abstract

<jats:sec> <jats:title>OBJECTIVE</jats:title> <jats:p>Pedicle screw instrumentation of the osteoporotic spine carries an increased risk of screw loosening, pullout, and fixation failure. A variety of techniques have been used clinically to improve pedicle screw fixation in the presence of compromised bone. Pedicle screws may be augmented with cement, but this may lead to cement leakage and result in disastrous consequences. To avoid these complications, a multiaxial expandable pedicle screw has been developed. This was a prospective, single-center study designed to evaluate the clinical results of patients with osteoporosis with traumatic and degenerative spinal diseases treated with expandable pedicle screws.</jats:p></jats:sec> <jats:sec> <jats:title>METHODS</jats:title> <jats:p>Thirty-three patients (mean age 61.4 years) with osteoporosis and traumatic or degenerative spinal diseases underwent spinal posterior fixation with expandable screws. Preoperative and postoperative visual analog scale (VAS) for pain and Oswestry Disability Index (ODI) questionnaire scores were obtained. The immediate postoperative screw position was measured and compared with the final position on lateral plain radiographs and axial CT scans at the 1- and 2-year follow-up examinations.</jats:p></jats:sec> <jats:sec> <jats:title>RESULTS</jats:title> <jats:p>A total of 182 pedicle screws were used, including 174 expandable and 8 regular screws. The mean preoperative patient VAS score improved from 8.2 to 3.6 after surgery. The mean ODI score improved from 83.7% before surgery to 29.7% after the operation and to 36.1% at the final follow-up. No screw migration had occurred at the 1-year follow-up, but 1 screw breakage/migration was visualized on spinal radiography at the 2-year follow-up.</jats:p></jats:sec> <jats:sec> <jats:title>CONCLUSIONS</jats:title> <jats:p>The results of this study show that the multiaxial expandable pedicle screw is a safe and practical technique for patients with osteoporosis and various spinal diseases and adds a valuable tool to the armamentarium of spinal instrumentation.</jats:p></jats:sec>

Reduced cement volume does not affect screw stability in augmented pedicle screws

“…There are different techniques to improve screw anchorage, e.g. expandable screws, lengthening of the construct or cement augmentation of the pedicle screws [25][26][27]. Clinical and biomechanical studies exhibited the benefits of augmentation in terms of higher pull-out forces, increasing fatigue loads in cyclic testing and reduced loosening rates in clinical studies [12,14,23,25].…”

Implant related complications in patients operated on with expandable pedicle screws and technical solutions for revision surgery

“…3,8,9 To prevent those complications, pedicle screw augmentation with bone cement and expandable screws were introduced into a clinical practice and it has been reported that expandable screws can provide a 25-50 per cent increase tolerance towards pull out forces applied to pedicle screws. 4,5,10,11 An additional benefit is that the application of expandable screws seems to be safer because this technology provides the opportunity to get rid of challenges associated with liquid cement injection. 10 In a study with a sample of 331 patient it has been shown that implant related complications rate is low if expandable screws are used as far as no screw loosening was detected, while implant breakage accounts for only 2.8 per cent.…”

“…It has been assumed that expandable screws are easy to remove if a revision surgery is required, however relevant studies were conducted either with screws of another design or just with biomechanical tests ex vivo. [3][4][5]11 It is plausible that ingrowth of tissues into expanded segment of screw that may additionally increase the fixation strength was not taken into account. The second issue that can be associated with the expandable screws is that a stronger anchorage in bone will not prevent screw breakage completely because of metal fatigue.…”

“…Surgical interventions were performed under the control of fluoroscopy, as described in manuscripts by Gazzeri and Vishnubhotla. 4,5 The duration of the follow-up period after primary instrumentation accounted for 18 months. Patients were given CT examinations at the period of 6, 12, and 18 months after interventions.…”

“…3 Potential hazards associated with bone cement application for augmentation are frequently discussed in literature; those are intracanal cement leakage, pulmonary embolism, cytotoxicity and poor feasibility for revision surgery. [3][4][5][6] For those reasons, some authors consider the application of expandable screws safer than augmentation of pedicle screws with cement, although the anchorage strength of the former is lower. [3][4][5] The aim of our study is to report rarely discussed implant related complications in patients which are operated on using expandable pedicle screws and to propose revision options in case of implant failure.…”