ABSTRACT
Objectives To evaluate the 3D printed navigation template used to assist axis pedicle lag-screw placement in the treatment of atypical Hangman's fracture(AHF).Methods From May 2015 to January 2017,12 patients with AHF were treated at Department of Orthopedics,The Fourth Peopled Hospital of Zigong.In their operation,the axis pedicle lag-screw placement was assisted by a 3D printed navigation template.They were 8 men and 4 women,aged from 27 to 53 years(average,45.6 years).There were 7 cases of type Ⅰ,4 cases type Ⅱ and one case of type HA according to the Levine-Edwards classification.There were 2 cases of grade D and 12 cases of grade E according to the assessment of America Spinal Injury Association(ASIA).Their preoperative and postoperative neck pain was evaluated by visual analogue scale(VAS);their preoperative and postoperative ranges of cervical motion were recorded and compared.To evaluate the postoperative safety of screws,the insertion point,position within the pedicle,axial angle and sagittal angle of the screws and maximum fracture displacement were compared between actual operation and simulative operation.Results A total of 12 guide plates were designed and printed;a total of 24 lag-screws were placed.All patients underwent surgery uneventfully.They were followed up for 12 to 20 months,with an average of 14.7 months.Two patients with ASIA grade D recovered to ASIA grade E at the last follow-up.All patients showed a significant improvement in neck pain.Their VAS score at 5 days after surgery(5.86±2.02) was significantly lower than their preoperative score(8.29±1.88)(P<0.05) and their VAS score at the last follow-up(1.73±0.87) was also significantly lower than that at 5 days after surgery(P<0.05).Their range of cervical motion at 6 months after surgery was significantly larger than that at 3 months after surgery(P<0.05);their range of cervical motion returned to normal roughly at the last follow-up,showing no significant difference from that at 6 months(P>0.05).Their postoperative X-ray and CT images showed that the dislocation was all corrected.The last follow-up showed no obvious vertebral instability,screw breakage or loosening.Postoperative CT showed that the 24 screws had been located completely in the pedicle(grade 0),indicating that the screw placement was 100% accurate.The postoperative deviation at insertion point(0.70±0.78 mm),deviation within the pedicle(1.3±0.82 mm),axial angle(8.26°±0.88°) and sagittal angle(22.62°±0.86°) of the screws showed no significant differences from the preoperative simulative data(P>0.05).There was a significant difference in the maximum fracture displacement between the preoperative data(3.94±0.38 mm) and the postoperative data(2.21±0.39 mm)(P<0.05).Conclusion The 3D printed navigation template can be used to better assist axis pedicle lag-screw placement in the treatment of AHF,because it ensures safe screw placement,leading to good reduction and fixation and precise match with the preoperative plan.
ABSTRACT
BACKGROUND: It has been found that the distribution and diffusion degree of bone cement are the main factors influencing the clinical effect of percutaneous vertebroplasty. OBJECTIVE: To explore the feasibility of analyzing bone cement distribution form and diffusion degree based on Mimics software, and to evaluate the relationship of clinical efficacy with bone cement distribution form and diffusion degree. METHODS: A total of 170 cases of osteoporotic vertebral compression fracture admitted to Zigong No. 4 People's Hospital from January 2017 to March 2018 were included, including 41 cases of males and 129 cases of females aged 60-97 years. All of them were treated with percutaneous vertebroplasty. X-ray and CT examination were done at postoperative 2 days, and the bone cement distribution was classified into five types based on the distribution of bone cement in X-ray images, including type Ⅰ (most cement continuously and evenly distributed in the vertebral body), type Ⅱ (most cement distributed in the central vertebral bodies), type Ⅲ (most cement distributed on both sides of vertebral body), type Ⅳ (most cement distribution at the side of the vertebral bodies and the central), type Ⅴ (most cement distribution at the side of the vertebral body). Mimics project files were created based on CT image data to calculate bone cement volume and diffusion volume. After 6 months of follow-up, visual analogue scale score, Oswestry disability index and Cobb angle were compared among groups to analyze the relationship between bone cement distribution, bone cement diffusion volume, bone cement diffusion volume ratio and clinical efficacy. RESULTS AND CONCLUSION: (1) The visual analogue scale score and Oswestry disability index of the five types of bone cements were significantly improved at 2 days and 6 months after surgery compared with preoperative data (P < 0.05), the Cobb angle of the type Ⅰ group was significantly improved compared with preoperative data (P < 0.05), and the Cobb angles of the type Ⅱ-Ⅴ groups showed no difference from the preoperative data (P> 0.05). (2) The diffusion volume of bone cement was (6.69±1.19) mL, and the diffusion volume ratio of bone cement was (20.93±3.13) ％. There was no correlation between the volume of bone cement injection and the visual analogue scale score, Oswestry disability index and Cobb angle at 2 days and 6 months after surgery. There was a negative correlation between the bone cement dispersion volume and the visual analogue scale score at 6 months after surgery, and the Oswestry disability index score at 2 days and 6 months after surgery (P < 0.05), but the correlation was weak. The diffusion volume ratio of bone cement was negatively correlated with the visual analogue scale score and Oswestry disability index score at 2 days and 6 months after surgery (P < 0.05), showing a strong correlation. These findings show that, based on the three-dimensional reconstruction function of Mimics software, the diffusion volume and diffusion volume ratio of bone cement can be accurately calculated. The bone cement evenly distributed can alleviate the local kyphosis. The diffusion volume ratio of bone cement is positively correlated with clinical efficacy, which is more valuable than the volume of bone cement.
ABSTRACT
Objective To explore the clinical efficacy of 3D printing technique in assisting sacroiliac screwing in combination with front ring nail-rod system for treatment of unstable pelvic fractures.Methods From July 2015 to June 2017,3D printing technique was used to assist the sacroiliac screwing in combination with front ring nail-rod system for 16 patients with unstable pelvic fracture at Orthopaedic Center,The Fourth People's Hospital of Zigong.They were 9 males and 7 females,aged from 19 to 60 years (average,39.8 years).By the Tile classification,5 cases were type B1,6 type B2,3 type B3 and 2 type C.Their operation duration,bleeding,fluoroscopy frequency,incision length,postoperative fracture reduction,success rate of sacroiliac screwing,accuracy of sacroiliac screwing,perioperative complications,weight-bearing exercise time,fracture healing time and the Majeed scores at the last follow-up were documented.Results All the 3D models and navigation templates were successfully designed and printed.Surgery succeeded in all the patients.Follow-ups ranged from 6 to 18 months,averaging 13.3 months.The bleeding ranged from 100 to 250 mL,averaging 162.4 mL;the operation duration ranged from 60 to 120 min,averaging 73.2 min;the intra-operative fluoroscopy frequency ranged from 13 to 31 times,averaging 17.4 times;the incision length ranged from 16 to 32 cm,averaging 21.1 cm.All the incisions healed by the first intention and all the fractures obtained osseous union after 90 to 120 d (average,102.3 d).No significant complications like neurovascular injury or pulmonary embolism happened.The weight-bearing exercise time ranged from 25 to 40 d,averaging 31.5 d.According to the Matta imaging scores,the reduction was rated as excellent in 12 cases and good in 4.Altogether 28 screws were inserted with a success rate of 100％.Compared with the preoperative simulated screwing,the actual screwing angle deviated postoperatively by 0.12° ± 0.32°,the X axis by 0.36 ± 1.24 mm,the Y axis by 0.36 ± 1.24 mm and the Z axis by 0.22 ± 1.26 mm,showing no statistically significant difference between the actual 3D deviations and the test value of 0 (P ＞ 0.05).Conclusion In the treatment of unstable pelvic fractures,3D printing technique can be used in preoperative preparation of the connecting rod in the front ring nail-rod system to assist the sacroiliac screwing,significantly shortening the operation duration,reducing bleeding,ensuring safe and accurate screwing,and facilitating functional recovery.