Pedicle screw fixation commonly uses a manual probe technique for preparation and insertion of the screw. However, the accuracy of obtaining a centrally located path using the probe is often dependent on the experience of the surgeon and may lead to increased complications. Fluoroscopy and navigation assistance improves accuracy but may expose the patient and surgeon to excessive radiation. DSG measures electrical conductivity at the tip and provides the surgeon with real-time audio and visual feedback based on differences in tissue density between cortical and cancellous bone and soft tissue. The authors investigated the effectiveness of DSG for training residents on safe placement of pedicle screws. 15 male cadaveric thoracolumbar spine specimens were fresh-frozen at the time of expiration. Residents were assigned 3 specimens each and randomised by pedicle side and order of technique for pedicle screw placement (free-hand versus DSG). Fluoroscopy and other navigation assistance were not used for pedicle preparation. All specimens were imaged using CT following insertion of all pedicle screws. The accuracy was assessed by a senior radiologist and graded as within (≤ 2mm breach) or outside (> 2mm breach) the pedicle.Introduction
Methods
To assess healing pattern of Achilles tendons across the gap created by a percutaneous tenotomy and maintained by cast in club feet. Twenty-one tenotomies in 16 patients (Age range 12 weeks-36 months) were monitored with dynamic and static ultrasonographic studies. Ultrasounds were performed before and immediately after tenotomy and at approximately 3, 6 and 12 weeks post tenotomy. Cast removal was done at three weeks. Two patients above age of two were casted for 6 weeks. The healing pattern went through different phases although they were not distinctively exclusive from each other and did show considerable overlap. First phase showed formation of a bulbous mass with some continuity of scar tissue across tendon gap. The transition zone between new fibre and the original tend quite distinct. However dynamic ultrasound showed the Achilles tendon moved as a single unit. Second phase showed fibres resembling normal tendon crossing the gap and reduction of bulbous mass. The transition zone was still discernible. Final stage demonstrated more homogenous fibres of Achilles tendon with an indistinct transition zone. Two older children showed a distinctly longer process of healing. One child showed an irregular mass of fluid and soft tissue structures in the gap at six weeks. The other child demonstrated a relative reduction in the proportion of tendon fibres across the gap. At 12 weeks there was evidence of continuation of tendon fibres, but transition zone partly visible. Young Child (<1 Year): when cast immobilisation is discontinued, the tendon is in mid phase of healing. There may be a positive effect on continued improvement in dorsiflexion while using boots and bars. Older Child: safe to consider percutaneous tenotomy in children up to 3 years of ages provided the period of immobilisation is extended.Conclusion
