Patient-specific plate for navigation and fixation of the distal radius: a case series.

PURPOSE: Corrective osteotomy of a malunited distal radius conventionally relies on 2D imaging techniques for alignment planning and evaluation. However, this approach results in suboptimal bone repositioning, which is associated with poor patient outcomes. In this case series, we evaluate the use of novel patient-specific plates (PSPs), which feature navigation and fixation of bone segments as preoperatively planned in 3D. METHODS: Ten participants with distal radius malunion underwent CT scans for preoperative alignment planning. Patient-specific guides and plates were designed, 3D-printed, and sterilized for use in corrective surgery of the distal radius. Pre- and postoperative results were compared in regard to clinical, functional, and radiographic outcomes. RESULTS: The application of a PSP was successful in 7 of the 10 cases. After treatment, the residual alignment error was reduced by approximately 50% compared with conventional treatment. The use of PSPs reduced pain significantly. Pre- and postoperative results were pooled and demonstrated significant correlations between: (1) pain and malpositioning, (2) the range of pro- and supination motion, the MHOQ score, the EQ-5D-5L score and dorsovolar angulation, and (3) MHOQ score and proximodistal translation. CONCLUSION: The correlation between malalignment and MHOQ score, EQ-5D-5L score, pain, and range of motion shows that alignment should be restored as well as possible. Compared to the conventional approach, which relies on 2D imaging techniques, corrective osteotomy based on 3D preoperative planning and intraoperative fixation with a PSP has been shown to improve bone alignment and reduce pain. LEVEL OF EVIDENCE: IV.

Positioning accuracy of a patient-tailored rimmed wedge implant for corrective osteotomy of the distal radius.

Conventional corrective osteotomy surgery is based on 2-D imaging for planning and evaluation of bone positioning. In this feasibility study we propose and evaluate the use of 3-D preoperative planning and design of a custom rimmed wedge to be inserted into the osteotomy gap. The shape of the wedge provides 3-D bone positioning as planned, while the rims keep the bone segments in place. The method is evaluated experimentally using 3-D printed radii specimens of five different malunion patients, as well as in a human cadaver specimen. Positioning was accurate and reproducible showing residual displacements along the x-, y- and z-axes of (mean ± SD): (-0.19 ± 0.75, 0.38 ± 1.09, and 0.47 ± 0.48) mm and residual rotations about these axes of (mean ± SD): (-1.22 ± 1.66, -0.40 ± 0.93, and -0.33 ± 1.50)° for artificial bone specimens. The cadaver experiment showed similar displacements along the x-, y- and z-axes (-0.17, 1.11, and -0.35) mm and residual rotations about these axes (-2.93, -1.53, and 2.31)°. Positioning by inserting a rimmed wedge in corrective osteotomy surgery is accurate with residual errors comparable to bilateral differences. The method seems promising for future utilization in corrective osteotomy surgery and may ultimately render the procedure minimally invasive.

Orbital Wall Reconstruction with Two-Piece Puzzle 3D Printed Implants: Technical Note.

The purpose of this article is to describe a technique for secondary reconstruction of traumatic orbital wall defects using titanium implants that act as three-dimensional (3D) puzzle pieces. We present three cases of large defect reconstruction using implants produced by Xilloc Medical B.V. (Maastricht, the Netherlands) with a 3D printer manufactured by LayerWise (3D Systems; Heverlee, Belgium), and designed using the biomedical engineering software programs ProPlan and 3-Matic (Materialise, Heverlee, Belgium). The smaller size of the implants allowed sequential implantation for the reconstruction of extensive two-wall defects via a limited transconjunctival incision. The precise fit of the implants with regard to the surrounding ledges and each other was confirmed by intraoperative 3D imaging (Mobile C-arm Systems B.V. Pulsera, Philips Medical Systems, Eindhoven, the Netherlands). The patients showed near-complete restoration of orbital volume and ocular motility. However, challenges remain, including traumatic fat atrophy and fibrosis.

A treatment algorithm for patients with large skull bone defects and first results.

Large skull bone defects resulting from craniotomies due to cerebral insults, trauma or tumours create functional and aesthetic disturbances to the patient. The reconstruction of large osseous defects is still challenging. A treatment algorithm is presented based on the close interaction of radiologists, computer engineers and cranio-maxillofacial surgeons. From 2004 until today twelve consecutive patients have been operated on successfully according to this treatment plan. Titanium and polyetheretherketone (PEEK) were used to manufacture the implants. The treatment algorithm is proved to be reliable. No corrections had to be performed either to the skull bone or to the implant. Short operations and hospitalization periods are essential prerequisites for treatment success and justify the high expenses.

A classification of cranial implants based on the degree of difficulty in computer design and manufacture.

BACKGROUND: Skull defects usually create aesthetic and functional disturbances to the patient. These defects are currently reconstructed by using computer-aided design and manufacturing processes. Classification of skull defects becomes important in discussing the complexity of reconstruction in clinical practice or comparing clinical results in scientific articles. METHODS: A more comprehensive classification, which takes into account not only the anatomical location but also the degree of difficulty in designing and manufacturing the implant, is presented here. It is not our intention to describe the different treatment modalities; therefore, only two clinical examples are presented to demonstrate the purpose of classification. RESULTS: The new classification enables a more detailed comparison of the clinical outcome of different modes of treatment for skull defects. CONCLUSIONS: The proposed classification reflects the degree of difficulty in designing and manufacturing of implants and can be very useful when comparing treatment results of skull defects for clinical or scientific purposes.