[Three-dimensional printing combined with distal humeral osteotomy for cubital varus deformity in children].

OBJECTIVE: To explore clinical effect of three-dimensional(3D) printing combined with distal humerus osteotomy for children with cubital varus deformity. METHODS: From January 2017 to January 2020, 17 cubital varus deformity children treated with distal humerus osteotomy were retrospective analysis, included 11 boys and 6 girls, aged from 5 to 11 years old with an average of (7.8±1.7) years old. A model of affected side elbow joint was made by 3D printing technique before operation, pre-operation was performed on the model. Three-dimensional model was successfully used for distal humeral osteotomy during operation. Carrying angle, flexion and extension angle of elbow joint were compared before and six months after operation, and Flynn scoring criteria was used to evaluate clinical effect. RESULTS: All children were followed up for 6 to 12 months with an avergae of (9.6±1.7) months. One child occurred wound infection and healed completely after dressing change. No complications such as nonunion, internal fixation and nerve injury occurred. Carrying angle of affected limb was improved from (-20.8±2.4)°before operation to (7.2±2.3)°at 6 months after operation (P<0.01). Angle of affected elbow joint extension improved from (-5.6±3.9)° before opeation to(-2.6±2.1)°at 6 months after operation (P<0.01). There was no significant difference in extension angle of elbow joint between preopertaion and postopertaion at 6 months (P>0.05). While there was no difference in elbow joint function on the healthy side and affected side at 6 months after opertaion (P>0.05). According to Flynn scoring criteria, 13 patients got excllent results and 4 moderate. CONCLUSION: Three-dimensional printing combined with distal humerus osteotomy in treating elbow varus deformity could receive satisfactory clinical effect, which could accurately assist correction of cubital varus deformity, restore physiological structure and function of elbow joint.

Effect of 3D Printing Technology in Proximal Femoral Osteotomy in Children with Developmental Dysplasia of the Hip.

OBJECTIVE: To investigate the effect and safety of 3D printing technology in proximal femoral osteotomy in children with developmental dysplasia of the hip. METHODS: 40 cases of children with developmental dysplasia of the hip treated by pelvic osteotomy combined with proximal femoral osteotomy at Ningbo No. 6 Hospital from January 2017 to December 2019 were retrieved and retrospectively analyzed. Among them, 20 cases received preoperative measurement and design assisted by 3D printing technology (the 3D printing group), and 20 cases received conventional preoperative measurement and design (the conventional group). RESULTS: All patients were followed up for an average of 25 (12~36) months. During the follow-up, there were no complications such as infection, fracture of internal fixation, or malunion of osteotomy. Compared with the conventional group, the 3D printing group had a shorter operation time, less intraoperative blood loss, and fewer intraoperative X-ray fluoroscopies (all p < 0.05). In the last follow-up, the clinical efficacy was evaluated by the McKay standard: in the 3D printing group, 14 cases were excellent, 5 cases were good, and 1 case was fair. In the conventional group, 10 cases were excellent, 9 cases were good, and 1 case was fair (Z = -0.382, p > 0.05). CONCLUSION: Preoperative 3D printing of bilateral femur and other large physical models is accurate, which is ideal for the development of individual preoperative planning. Proximal femoral osteotomy using preoperative measurements and simulated surgical data improves the safety of the operation.

Case Report: Unusual Presentation of Myositis Ossificans of the Elbow in a Child Who Underwent Excessive Postoperative Rehabilitation Exercise.

Traumatic myositis ossificans (MO) is an unusual complication after muscle injury and is predominantly seen in young adults and adolescents. Pediatric MO cases are even rarer. We report an 8-year-old girl who was diagnosed with a lateral humeral condyle fracture. She was treated surgically, and her elbow joint was fixed with plaster. Rehabilitation exercise was administered 1 month after the operation. Due to the wrong exercise method, a palpable bony mass appeared around the elbow 1 month later. The clinical radiological diagnosis showed MO, and conservative treatment was administered. After 3 years of follow-up, the affected limb functioned well, with no sign of recurrence. Here, we report this long-term follow-up case of MO resulting from excessive rehabilitation exercise.

Type III Monteggia Injury With Ipsilateral Distal Forearm Fracture in a Child: A Case Report.

Monteggia fracture refers to breakage of the upper third of the ulna combined with dislocation of the radial head. It often occurs in children and adolescents and represents a combined injury. Fracture of the distal forearm is among the most common trauma suffered by children. However, distal forearm fractures have rarely been reported as having an association with Monteggia fractures. We report on a 9-year-old boy diagnosed with a type III Monteggia fracture combined with a distal forearm fracture. He underwent surgery and received rehabilitation training 1 month later. He was followed-up for 1 year. The affected limb functioned well with no sign of radial head dislocation.

[Measurement of femoral neck anteversion of developmental dislocation of hip in children by 3D printing technique].

OBJECTIVE: To explore the method and accuracy of measuring the femoral neck anteversion in children with developmental dislocation of the hip by using 3D printing technology, so as to find out the method of measuring the femoral neck anteversion accurately and guide the formulation of the operation plan. METHODS: From June 2016 to September 2018, 17 patients with unilateral developmental dislocation of the hip were enrolled in the study, including 2 males and 15 females, aged 2 to 13 (5.47±0.81) years old, 11 on the left and 6 on the right. The methods of CT, 3D printing and intraoperative anteversion of femoral neck were used to measure the anteversion of femoral neck respectively. The intraoperative measurement was used as the standard reference value forstatistical analysis, and the accuracy of the first two methods was compared. RESULTS: The average value of CT was (36.00±1.66)°, the average value of model method was(43.91±1.62)°, and the average value of intraoperative method was(44.21±1.62)°. There were significant differences in CT measurement, model measurement and intraoperative measurement(P<0.05). There was no significant difference between model method and intraoperative method (P>0.05). CONCLUSION: Compared with the traditional CT method, the 3D printing model method is simpler, more accurate and more repeatable, and can simulate the operation before operation. It is an ideal method to measure the femoral neck anteversion.

[Experimental study on internal fixation with screws through femoral epiphyseal plate].

OBJECTIVE: To explore the effect of internal fixation with screw through femoral epiphyseal plate on growth in- hibition via an experimental study. METHODS: Forty New Zealand rabbits were randomly divided into 4 groups and 10 rabbits in each group. Epiphyseal plate was injured by penetrating of screws, and the size of damage area was controlled by changing the number of threads. Group A: blank group; group B: injury area accounted for 4% of the epiphyseal plate; group C: injury area accounted for 6%; group D: injury area accounted for 8%. The internal fixation was removed after 2 weeks, and the results were observed with X-ray film for 4 groups to judge the complications such as early closure of epiphyseal. RESULTS: In each group, there were no statistical differences in the length of the femoral neck, the diameter of femoral neck, the diameter of the femoral head, and the epiphyseal plate closure time. The growth speed of the length and diameter of the femoral neck, as well as the diameter of femoral head, were quicker on the early phase, and the speed was slowest when the epiphyseal plate was being closed. CONCLUSION: The injury area of epiphyseal plate under 8% is safe for its growth. Because no evidences demonstrate the growth inhibition of epiphyseal plate, the screws can be used for rabbit epiphyseal plates.

[An imaging study on location of the anterior border of facets and the posterior border of vertebral bodies in lower cervical spine].

OBJECTIVE: To explore the location of the anterior border of facets and the posterior border of vertebral bodies in lower cervical spine,and to provide a quantitative data to evaluate the correct length of transarticual screws in lower cervical spine during procedure. METHODS: One hundred standard lateral X-ray films and fifty CT films on cervical spine were used to measure the distance of the anterior border of facets and the posterior border of vertebral bodies in lower cervical spine. HS, HM and HI were defined as parameters, which means the distance between the anterior border of the superior (HS), median (HM) and inferior (HI) part of facets and the posterior border of corresponding vertebral bodies. The value will be negative if the anterior border of the facet located before the vertebral body. RESULTS: 'HS > HM > HI' was found in all facets in lower cervical spine. The anterior border of the facet in C(3,4) located before the posterior border of the vertebral body of C3. The anterior border of C(4,5) and C(5,6) was inclined to posterior. The anterior border of C(6,7) located after the posterior border of the vertebral body of C6. The pattern of HS increased from C(3,4) to C(6,7), the minimal (0 +/- 0.25) mm and the maximal (2.91 +/- 1.05) mm. The tendency of HM raised from C(3,4) to C(6,7), the minimal (-1.57 +/- 0.53) mm and the maximal (1.54 +/- 0.39) mm. The pattern HI added from C(3,4) to C(6,7), the minimal (-2.03 +/- 0.40) mm and the maximal (1.08 +/- 0.70) mm. CONCLUSION: During the implantation of the transarticular screws, the tip of the screws should be 0-2 mm before the posterior border of the vertebral body of C3 at C(3,4), 0-2 mm after that of C4 at C(4,5), 0.5-2.5 mm at C(5,6) and 1-3 mm at C(6,7). The quantitative location between the anterior border of facets and the posterior border of the corresponding vertebral bodies can offer an indirect method to evaluate the correct length of transarticual screws in lower cervical spine during procedure.