Study design. Retrospective study. Objectives. To optimise the radiation doses and image quality for the cone-beam O-arm surgical imaging system in spinal surgery. Summary of Background. Neurovascular compromise has been reported following screw misplacement during thoracic pedicle screw insertion. The use of O-arm with or without navigation system during spinal surgery has been shown to lower the rate of screw misplacement. The main drawback of such imaging surgical systems is the high radiation exposure. Methods. Chest phantom and cadaveric pig spine were examined on the O-arm with different scan settings: two were recommended by the O-arm manufacturer (120 kV/320 mAs, and 120 kV/128 mAs), and three low-dose settings (80 kV/80 mAs, 80 kV/40 mAs, and 60 kV/40 mAs). The radiation doses were estimated by Monte Carlo calculations. Objective evaluation of image quality included interobserver agreement in the measurement of pedicular width in chest phantom and assessment of screw placement in cadaveric pig spine. Results. The effective dose/cm for 120 kV/320 mAs-scan was 13, 26, and 69 times higher than those delivered with 80 kV/80 mAs, 80 kV/40 mAs, and 60 kV/40 mAs-scans, respectively. Images with 60 kV/40 mAs were unreliable. Images with 80 kV/80 mAs were considered reliable with good interobserver agreement when measuring the pedicular width (random error 0.38 mm and intraclass correlation coefficient 0.979) and almost perfect agreement when evaluating the screw placement (κ-value 0.86). Conclusions. The radiation doses of the O-arm system can be reduced 5–13 times without negative impact on image quality with regard to information required for spinal surgery

Many operations have been recommended to treat Pars Interarticularis fractures that have separated and are persistently symptomatic, but little other than conservative treatment has been recommended for symptomatic incomplete fractures. 10 consecutive patients aged 15–28 [mean 21.7 years] were treated operatively between 2010–2014. All but one were either professional athletes [3 cricketers, 2 athletics, 1 soccer] or academy cricketers [3 patients]. 8 patients had unilateral fractures, and two had bilateral fractures at the same level. The duration of pre-operative pain and disability with exercise ranged from 4–24 months [mean 15.4 months]. The operation consists of a percutaneous compression screw inserted through a 1.5cm midline skin incision under fluoroscopic guidance: 6 cases were also checked with the O-arm intra-operatively. Post-operation the patients were mobilised with a simple corset and discharged the following day with a customised rehabilitation program. All 12 fractures in 10 patients healed as demonstrated on post-operative CT scans at between 3–6 months. One patient had the screw revised at 24 hours for an asymptomatic breach, and one patient developed a halo around the fracture site without screw loosening, and had a successful revision operation to remove the screw and graft the pars from the screw channel. All patients achieved a full return to asymptomatic activity, within a timescale of 4–12 months post-surgery, depending on the sport. Athletes that have persistent symptoms from incomplete pars interarticularis fractures should consider percutaneous fixation rather than undergoing prolonged or repeated periods of rest

Pedicle screws as the principal anchors of instrumentation in correction of scoliosis as described by Suk 15 years ago have now gained a wide acceptance among deformity surgeons. Pedicles in the concavity of the major as well as compensatory curves are often dysplastic making screw placement occasionally problematic. In cases of dural ectasia with dystrophic pedicles, the transpedicular screw anchorage is sometimes impossible. In 2009 Gardner et al. presented a case of NF-1 with a troublesome cervico-thoracic kyphosis where they created distal anchors by means of laminar screw fixation. In the presentation of this case, the idea is further developed. Case. A 14 year old girl without any obvious syndromic feature underwent surgery for a 70 degree thoracic scoliosis. A preoperatively MRI showed a dural ectasia. A preoperative low dose–CT revealed dystrophic pedicles from Th4 to L4, making transpedicular screw placement problematical. The operation was performed with the aid of an O-arm. At all levels from Th2 – L2 laminar screw fixation was used. Postoperatively, low-dose CT showed excellent screw positioning with the exceptiuon of one proximal screw which compromised a foramem but, without any symptoms. The postoperative course was quite uneventful and the patient was discharged at day 5days postoperatively. The correction rate was 70%. Conclusion. In cases of scoliosis with severe dystrophic pedicles, the use of laminar screws is a good alternative to problematic transpedicular screw placement

Aims

The direct posterior approach with subperiosteal dissection of the paraspinal muscles from the vertebrae is considered to be the standard approach for the surgical treatment of adolescent idiopathic scoliosis (AIS). We investigated whether or not a minimally-invasive surgery (MIS) technique could offer improved results.

With the identification of literature shortfalls on the techniques employed in intraoperative navigated (ION) spinal surgery, we outline a number of measures which have been synthesised into a coherent operative technique. These include positioning, dissection, management of the reference frame, the grip, the angle of attack, the drill, the template, the pedicle screw, the wire, and navigated intrathecal analgesia. Optimizing techniques to improve accuracy allow an overall reduction of the repetition of the surgical steps with its associated productivity benefits including time, cost, radiation, and safety.

Cite this article: Bone Joint J 2020;102-B(3):371–375.

Aims

Intraoperative 3D navigation (ION) allows high accuracy to be achieved in spinal surgery, but poor workflow has prevented its widespread uptake. The technical demands on ION when used in patients with adolescent idiopathic scoliosis (AIS) are higher than for other more established indications. Lean principles have been applied to industry and to health care with good effects. While ensuring optimal accuracy of instrumentation and safety, the implementation of ION and its associated productivity was evaluated in this study for AIS surgery in order to enhance the workflow of this technique. The aim was to optimize the use of ION by the application of lean principles in AIS surgery.

Aims

Minimally invasive transforaminal lumbar interbody fusion (MITLIF) has been well validated in overweight and obese patients who are consequently subject to a higher radiation exposure. This prospective multicentre study aimed to investigate the efficacy of a novel lumbar localisation system for MITLIF in overweight patients.