The impact of surgical guide design and bone quality on heat generation during pilot implant site preparation: an in vitro study

BACKGROUND

Surgical guides restrict the flow of cooling agent to osteotomy site, which will lead to a temperature rise that provokes tissue injury. Few studies compared differences in the temperature changes between non-limiting 'conventional' and limiting 'guided' surgical guides during implant site preparation. The objective of this study was to investigate the difference in temperature changes during bone drilling for implant placement using non-limiting and limiting surgical guides at cortical and cancellous bone levels.

METHODS

Forty-four bovine rib samples were used for implant bed preparation in this study with a minimum thickness of 11 mm was chosen for the ribs. The bone was stored in a freezer at 10 °C until it was used. On the day of the study, the bone was defrosted and soaked in water at 21 °C for three hours before embarking on drilling to make sure each sample was at the same temperature when tested. Forty-four bone specimens were prepared and randomly allocated to receive either a limiting or a non-limiting surgical guides (22 for each group). The osteotomy site was prepared by one operator following the manufacturer's instructions, using limiting and non-limiting surgical guides. Temperature changes were recorded during implant bed preparation using thermocouples that fit into 7 mm-horizontal channels at two different depths (Coronally) and (Apically) at 1 mm distance from the osteotomy site. The data were tested for homogeneity of variances using Levene's test, then data were analyzed using an Independent sample t-test and the significance level was set at P ≤ 0.05.

RESULTS

The mean temperature rise for all samples was 0.55 °C. The mean temperature rises for the limiting and non-limiting surgical guides were 0.80 °C and 0.33 °C respectively. There was a statistically significant difference in temperature rise between the limiting and non-limiting surgical guides (P = 0.008). In relation to position of temperature recording (coronal vs. apical), there was no significant difference (P > 0.05). No significant difference was noted between the two groups at cancellous bone level (P = 0.68), but the difference was significant at cortical bone level (P = 0.036).

CONCLUSION

Limiting surgical guides showed higher readings than non-limiting. However, for both techniques, temperature rise was not significant clinically and within a safe range.

[Preliminary development of guided template of middle and upper thoracic percutaneous vertebroplasty in thoracic pedicle approach due to three dimentional soft tissue print technique]

OBJECTIVE

To investigate the feasibility of a drill template for the placement of guided template of middle and upper thoracic percutaneous vertebroplasty in thoracic pedicle approach on digital design and 3D printing technology.

METHODS

The preoperative CT images of 20 patients with thoracic fracture were collected retrospectively. With the 3D soft tissue printing technology, the data was reconstructed by 3D imaging reconstruction software to produce 1∶1 three dimensional soft tissue model. The pedicle screw channel and the digital template were designed by the 3-matic module of Mimics15.0 software. After guide template was printed by 3D printer and three dimensional template was fixed on the model, 2.0 mm Kirschner was placed and the accuracy of a drill template was observed by CT scans, bone cement was injected through the puncture tube and verified with images. The time of nail guide design, guide template production and cost were recorded.

RESULTS

The effectiveness of three dimensional thoracic model and digital guided template of middle and upper thoracic percutaneous vertebroplasty of thoracic fractures in thoracic pedicle approach was confirmed. Kirschner was placed and the accuracy of screw placement was confirmed with CT scanning. Template and the corresponding anatomical landmark fitted well, bone cement had showed good filling. The average printing time of upper thoracic spine model with soft tissue, the mean time of nail guide design, guide template production and cost were (719.00±3.03) min, (12.30±1.01) min, (55.50±10.30) min and RMB 3 150 yuan on average respectively.

CONCLUSION

By means of individual design and 3D soft tissue printingtechnology, accurate placement of guided template of middle and upper thoracic percutaneous vertebroplasty could be realized.

[linical application of personalized 3D printing-guided template of intramedullary lag screw insertion on lateral superior ramous of pubic]

OBJECTIVE

To evaluate the efficacy and advantages of personalized 3D printing-guided template of lateral superior ramous of pubic intramedullary lag screw.

METHODS

From July 2015 to December 2016, 20 patients with the superior and inferior ramous of pubis fracture were treated with lag screws placement. All the patients were divided into test group(with guided template) and control group(with general operation). There were 7 males and 3 females with an average age of (46.20±3.03) years old in test group and 6 males and 4 males with (48.50±2.25) years old in control group. There were 6 cases and 5 cases of superior and inferior branches fractures of pubic on the left side and 4 cases and 5 cases on the right side in two groups respectively. The operation time, perspective times and bleeding loss were compared between two groups.

RESULTS

The test group and the control group had no statistically significant relative to gender, age, fracture classification. The average time of surgery, average intraoperative fluoroscopy times, mean blood loss in test group were (31.0±5.3) min, (3.5±2.1) times, (75.6±10.5) ml respectively, and in control group were(55.0±6.8) min, (27.6±3.2) times, (85.5±12.5) ml respectively. There were significant Statistical differences between two groups(P<0.05) in average operation time and average fluoroscopy times, however, mean blood loss had no significant differences between two groups(P>0.05).

CONCLUSIONS

The personalized guide template based on 3D printing technology could realize precise placement of the lateral intramedullary lag screw fixation in the superior branch of pubic, also could save the operation time and reduce the times of radiation exposure of patients and surgeons.