[A preliminary study of three-dimensional printed porous titanium plate integrated implant for the repair of comminuted acetabular posterior wall fracture with bone defect]

OBJECTIVE

To explore the feasibility of using computer-aided design(CAD) combined with 3D printing technology to repair and reconstruct the comminuted fracture of the posterior wall of acetabulum with osteochondral defect, to evaluate the biomechanical properties of composite titanium nitride bioceramic coatings with porous titanium alloy scaffolds and steel plate integrated implants.

METHODS

Based on CT images of continuous tomography, the computer-aided design software was used to construct a digital model of porous titanium alloy plate implant with a specially open cellular three-dimensional structure, and the three-dimensional implant was prepared with Ti6Vl4V powder by using the 3D printing technology, following by titanium nitride coating on its articular surface. The degree of matching and attachment between the implant and acetabulum were observed; Ansys software was used for finite element modeling to analyze the stress distribution, stress conduction and deformation displacement of the acetabulum of the normal group, the traditional group and the implant group under the same load state, and to verify the biomechanical properties of the implant.

RESULTS

The porous titanium alloy implant fit well with the acetabular bone defects, the shape of the plate was well attached to the bone surface, and it was rated as excellent according to the Matta criteria. The Von Mises stress peak of the implant group 13.38 MPa was close to the normal group 13.11 MPa and smaller than that in the traditional group 15.66 MPa. The Von Mises stress distribution and conduction of implant group were basically consistent with the normal group, slightly better than the traditional group; the maximum relative displacement of the implant was 0.166 mm, according to the finite element analysis.

CONCLUSIONS

The porous titanium alloy stent plate implant with titanium nitride coating prepared by 3D technology has excellent matching degree and biomechanical properties; the anatomical reconstruction makes the stress distribution and conduction recovery well, close to normal hip joints, which provides a new option for the clinical treatment of comminuted posterior acetabular wall fractures with severe bone defects.

[Treatment of old acetabular posterior wall fracture with 3D printing combined with composite plate internal fixation]

OBJECTIVE

To explore the application value and clinical effect of three-dimensional printing combined with composite plate internal fixation in the treatment of old acetabular posterior wall fracture.

METHODS

From May 2010 to October 2016, Mimics 19.0 software was used to plan preoperatively according to a 1:1 print pelvic 3D model. At the same time, 23 patients with old acetabular posterior wall fractures were treated with combined plate internal fixation, including 15 males and 8 females, aged 20 to 63 (43.0±5.1) years old, and the time from injury to operation was 23 to 101(47.0±10.5) days. According to Letournel-Judet classification, 11 cases were posterior wall fracture, 7 cases were transverse with posterior wall fracture, and 5 cases were posterior column with posterior wall fracture. All patients were treated with single Kocher-Langenbeck approach combined plate internal fixation, and the evaluation indexes were recorded during operation, after operation and during follow-up.

RESULTS

The operation time of 23 patients was (113.5±11.5) min, bleeding was (550.0±104.7) ml and fluoroscopy was (12.7±0.8) s. Matta radiographic reduction criteria were used: excellent in 14 cases, good in 7 cases and poor in 2 cases; 23 patients were followed up for 10 to 24 (16.0±5.6) months. The hip function was evaluated according to the modified Merle d'Aubingne and Postal scoring system at the last follow-up: excellent in 11 cases, good in 8 cases, fair in 3 cases and poor in 1 case. There were 3 cases of traumatic arthritis, 1 case of femoral head necrosis, 2 cases of heterotopic ossification and 5 cases of sciatic nerve irritation.

CONCLUSIONS

3D printing technique is an effective and fast method for the treatment of old acetabular posterior wall fractures. In addition, the printing model can provide three-dimensional morphological structure for the operator, combined with preoperative simulation, facilitate intraoperative reduction, and effectively improve the efficiency of surgery.

[Application of three-dimensional printing technology to design individual angle section on Chevron of hallux valgus osteotomy]

OBJECTIVE

To explore clinical application of three-dimensional printing technology to design individual angle section on Chevron of hallux valgus osteotomy.

METHODS

From May 2013 to May 2016, 47 patients(66 feet) with mild to moderate hallux valgus treated by Chevron osteotomy according to different preoperative design were divided into computer osteotomy group(group A) and traditional osteotomy group(group B). In group A, there were 25 patients (33 feet), including 4 males(5 feet) and 21 females(28 feet) with an average age of (47.88±6.08) years old, average weight IMA was (13.58±1.15) degree, AOFAS score was 59.00±5.86, and treated individual 3D printing technology to design operation scheme. While in group B, there were 22 patients (33 feet), including 3 males (3 feet) and 19 females (28 feet) with an average age of (48.16±6.16) years old, average weight IMA was(13.51±1.14) degree, AOFAS score was 60.67±5.85, and treated with osteotomy according to surgical experience. Operation time, blood loss, hospital stays, VAS score at 1 week after operation, wound healing and improvement of postoperative weight-bearing intermetatarsal angle(IMA) were compared between two groups, AOFAS score system was used to evaluate ankle function after surgery.

RESULTS

There was no significant difference in following-up between group A 12.41±2.32 and group B 11.73±2.76. There was 1 patient in group B were excluded. Others perform good wounds healing on the first stage after operation. There were no significant differences in operation time, blood loss, hospital stays and VAS score at 1 week after operation(P<0.05); IMA in group A was (5.21±0.88)°, (6.42±0.85)° in group B, and had significant differences between two groups (t=5.68, P<0.05). There was obvious meaning in AOFAS score between group A 88.15±5.19 and group B 82.90±5.01(t=4.14, P<0.05). Fourteen feet in group A obtained excellent results and 19 feet good, while 5 feet in group B obtained excellent results and 27 feet good.

CONCLUSIONS

Compared with traditional osteotomy group, three-dimensional printing technology to design individual angle section on Chevron of hallux valgus osteotomy could better correct IMA, improve postoperative foot function, and it is a kind of individualized and digital method to design operation.