A composite 3D printed model of the midcarpal joint

Carpal bone replacement using personalized 3D printed tantalum prosthesis

Objective: Scaphoid and lunate fractures have a relatively high incidence rate. Traditional carpectomy and carpal arthrodesis in the treatment of carpal osteonecrosis will lead to many complications. Three-dimensional (3D) printed tantalum has good biocompatibility and can be designed to match the patient's personalized anatomical carpal structure. This study aims to investigate carpal function and prosthesis-related conditions after carpal bone replacement using 3D printed tantalum prostheses. Methods: From July 2020 to January 2022 at our center, seven patients with osteonecrosis of the carpus received carpal bone replacement using 3D printed tantalum prosthesis. The Disability of the Arm, Shoulder and Hand (DASH) score and patient satisfaction, as well as the Mayo Wrist Scores (Cooney method, modified Green, and O'Brien wrist score), were used to evaluate the preoperative and postoperative wrist function of patients. The Visual Analog Scale (VAS) pain scores were also recorded before and after surgery. The angles of flexion, dorsiflexion, ulnar deviation, and radial deviation were measured using an arthrometer. The grip strength and pinch strength of the operated hand after carpal bone replacement and the contralateral healthy carpus were measured using a dynamometer. Radiographs were taken to confirm the condition and complications of the tantalum prosthesis. Results: All seven patients were followed for 19.6 ± 2.7 months. At the last follow-up, the grip strength of the operated wrist joint after carpal bone replacement was 33.4 ± 2.3 kg, the pinch strength was 8.9 ± 0.7 kg, the flexion was 54.6° ± 0.8°, the dorsiflexion was 54.7° ± 1.7°, the ulnar deviation was 34.6° ± 1.9°, and the radial deviation was 25.9° ± 0.8°, all of which showed no statistically significant difference with the contralateral healthy carpus (p > 0.05). There were significant differences in the VAS, DASH, and MAYO scores between the preoperative and the last follow-up (p < 0.01). Patients had reduced postoperative pain and improved wrist function and range of motion (ROM), and the tantalum prostheses were stable. Conclusion: The 3D printed tantalum brings us new hope, not only for hip or knee replacement, but also for joint replacement of other complex anatomical structures, and patients with other irregular bone defects such as bone tumors and deformity, which could realize personalized treatment and precise medicine.

3D printing as a pedagogical tool for teaching normal human anatomy: a systematic review

BACKGROUND

Three-dimensional-printed anatomical models (3DPAMs) appear to be a relevant tool due to their educational value and their feasibility. The objectives of this review were to describe and analyse the methods utilised for creating 3DPAMs used in teaching human anatomy and for evaluating its pedagogical contribution.

METHODS

An electronic search was conducted on PubMed using the following terms: education, school, learning, teaching, learn, teach, educational, three-dimensional, 3D, 3-dimensional, printing, printed, print, anatomy, anatomical, anatomically, and anatomic. Data retrieved included study characteristics, model design, morphological evaluation, educational performance, advantages, and disadvantages.

RESULTS

Of the 68 articles selected, the cephalic region was the most studied (33 articles); 51 articles mentioned bone printing. In 47 articles, the 3DPAM was designed from CT scans. Five printing processes were listed. Plastic and its derivatives were used in 48 studies. The cost per design ranged from 1.25 USD to 2800 USD. Thirty-seven studies compared 3DPAM to a reference model. Thirty-three articles investigated educational performance. The main advantages were visual and haptic qualities, effectiveness for teaching, reproducibility, customizability and manipulability, time savings, integration of functional anatomy, better mental rotation ability, knowledge retention, and educator/student satisfaction. The main disadvantages were related to the design: consistency, lack of detail or transparency, overly bright colours, long printing time, and high cost.

CONCLUSION

This systematic review demonstrates that 3DPAMs are feasible at a low cost and effective for teaching anatomy. More realistic models require access to more expensive 3D printing technologies and substantially longer design time, which would greatly increase the overall cost. Choosing an appropriate image acquisition modality is key. From a pedagogical viewpoint, 3DPAMs are effective tools for teaching anatomy, positively impacting the learning outcomes and satisfaction level. The pedagogical effectiveness of 3DPAMs seems to be best when they reproduce complex anatomical areas, and they are used by students early in their medical studies.