Preliminary application of 3D-printed individualised guiding templates for total hip arthroplasty in Crowe type IV developmental dysplasia of the hip.

OBJECTIVE: To evaluate the feasibility and accuracy of three-dimensional (3D)-printed individualised guiding templates in total hip arthroplasty (THA) for the treatment of developmental dysplasia of the hip (DDH). METHODS: 12 hips in 12 patients with Crowe type IV DDH were treated with THA. A 3D digital model of the pelvis and lower limbs was reconstructed using the computed tomography data of the patients. Preoperative surgical simulations were performed to determine the most suitable surgical planning, including femoral osteotomy and prosthesis placement. Based on the ideal surgical planning, individualised guiding templates were designed by software, manufactured using a 3D printer, and used in acetabulum reconstruction and femoral osteotomy during surgery. RESULTS: 12 patients were followed up for an average of 72.42 months (range 38-135 months). During surgery, the guiding template for each case was matched to the bony markers of the acetabulum and proximal femur. Preoperative and follow-up Harris Hip Scores were 34.2 ± 3.7 and 85.2 ± 4.2; leg-length discrepancy, 51.5 ± 6.5 mm and 10.2 ± 1.5 mm; and visual analogue scale scores, 6.2 ± 0.8 and 1.3 ± 0.3, respectively, with statistical difference. Shortened deformity and claudication of the affected limb were obviously improved after surgery. However, 1 patient had artificial hip dislocation 2 weeks after surgery, and another patient had sciatic nerve traction injury, both of whom recovered after physical treatment. CONCLUSIONS: Preoperative surgical simulation and 3D-printed individualised guiding templates can fulfil surgeon-specific requirements for the treatment of Crowe type IV DDH. Accurate THA can be achieved using 3D-printed individualised templates, which provide a new personalised surgical plan for the precise positioning and orientation of acetabular reconstruction and femoral osteotomy.

[Application of 3D digital orthopedic techniques in treatment of acetabular fracture].

OBJECTIVE: To evaluate the therapeutic effect of three-dimensional digital orthopedic techniques in treatment of acetabular fractures. METHODS: We retrospectively analyzed 50 cases of acetabular fracture treated between March, 2007 and December, 2013. The lamellar CT scanning data were imported into Mimics software, and 3D anatomical models of the pelvic and proximal femur were reconstructed. Computer-assisted analysis was carried out to understand the condition of fractures and simulate fracture reduction. The pelvic models were manufactured by rapid prototyping technique for definite diagnosis and typing of acetabular fractures and subsequent surgical treatment. RESULTS: Three-dimensional reconstruction images and rapid prototyping pelvic models faithfully represented the findings in operations. Preoperative simulation of the operation shortened the time of operation and reduced the volume of bleeding in the operation. All the patients were followed up for 6 to 24 months. According to Matta imaging score, anatomical reduction was achieved in 41 cases and satisfactory reduction in 9 cases. According to the Harris functional criteria, 32 patients had excellent, 12 had good and 6 had acceptable outcomes with a rate of excellent and good outcomes of 88%. CONCLUSION: Three-dimensional digital orthopedic techniques allow accurate display of the acetabulum and the spatial relation of the anatomic structures to assist in fracture diagnosis, typing and treatment.

Biomechanical effect of medial cortical support and medial screw support on locking plate fixation in proximal humeral fractures with a medial gap: a finite element analysis.

OBJECTIVE: This finite element analysis aimed to examine the effect of medial cortical support and medial screw support on loads at the implant-bone interface of locking plate fixation of proximal humeral fractures with a medial gap. METHODS: An intact humerus from a healthy volunteer was used as the basis for a 3-dimensional (3D) computer-aided design (CAD) model. The 3D CAD model of the locking plate system was based on information in the manufacturer's catalogue. The proximal part of the humerus was osteotomized to create standard three-part fractures, which were then divided into a -MSC group (which lacked medial cortical support, and in which fractures with a 5-mm medial bone gap simulated this lack) and +MCS group (which had medial cortical support, and in which fractures with medial cortical-to-cortical contact simulated this). Both fracture groups were respectively fixed with either +MSS (in which medial screw support was simulated by the addition of two calcar screws to the locking plate system), or with -MSS (in which the lack of medial screw support was simulated by absence of the two additional calcar screws to the locking plate system). All the modeling was conducted to represent 90° arm abduction. RESULTS: On the screw-bone interface, medial screw support and medial cortical support decreased maximum shear stress by 17% and 23% respectively. On the locking plate, medial screw support and medial cortical support decreased maximum von Mises stress by 11% and 22% respectively. However, a combination of these two appeared to decrease maximum shear stress by 56% for the screw-bone interface, and maximum von Mises stress by 54% for the locking plate. CONCLUSION: Placement of calcar screws combined with good medial cortical contact in varus in locking plate fixation of proximal humeral fractures with a medial gap may provide optimal stability for the fixation.