Ladislav Nagy

Rotational deformities of the forearm occur due to neurological imbalance of pro/supinating forces, commonly seen in brachial plexus birth injury. Brachioradialis rerouting has been described for the correction of active pronation or supination deficits. Fixed deformities cannot be addressed by soft tissue procedures alone, and need derotational osteotomies. More recently, techniques combining biceps rerouting and forearm osteotomy have been described. We present an alternative technique to correct fixed rotational forearm deformities by derotational forearm osteotomy and brachioradialis tendon rerouting. The technique can be used to correct both supination and pronation deformities, because the brachioradialis tendon can be rerouted to support either of the 2. No tenotomy and no tendon reconstruction has to be performed. This allows for early mobilization and eliminates the risk of complications at the site of tendon reconstruction.

Background: Scaphoid reconstruction after an established non- or malunion is challenging and recent developments have shown the feasibility to reconstruct it with 3D-planned and -printed patient-specific instrumentation. Methods: Our study compared the clinical outcome of computer assisted 3D-reconstructions of the scaphoid using patient-specific guides for primary and revision reconstructions of scaphoid nonunion regarding clinical outcome. Therefore, 39 patients with primary scaphoid nonunion or malunion and 15 patients with nonunion or malunion after a previous operative treatment were treated with patient-specific guides and followed up for a mean of 10.5 months. The consolidation was assessed with a CT-scan, and the time to consolidation was recorded. Pain level, satisfaction, wrist range of motion, and grip strength were measured and compared. Results: The wrist range of motion and grip strength of the two groups were similar, except for the wrist extension, which was significantly reduced in the revision group. Consolidation was observed in 36/39 patients (92%) in the primary group and in 13/15 patients (87%) in the revision group. Our results showed similar clinical results postoperatively between primary reconstructions and revision surgery. Conclusions: The use of 3D-planned and -printed patient-specific instrumentation proves to be similarly effective in revision surgeries for the reconstruction of the scaphoid as it is in primary surgeries.

A retrospective, single center, data analysis. Persistent pain and instability are common complications after distal ulnar head arthroplasty. One main reason may be the insufficient representation of the anatomical structures with the prosthesis. Some anatomical structures are neglected such as the ulnar head offset and the ulnar torsion which consequently influences the wrist biomechanics. CT scans of the ulnae of forty healthy and asymptomatic patients were analyzed in a three-dimensional surface calculation program. In the best fit principle, cylinders were fitted into the medullary canal of the distal ulna and the ulnar head to determine their size. The distance between the central axes of the two cylinders was measured, which corresponds to the ulnar offset, and also their rotational orientation was measured, which corresponds to the ulnar torsion. The mean medullary canal diameter was 5.8 mm (±0.8), and the ulnar head diameter was 15.8 mm (±1.5). The distance between the two cylinder axes was 3.89 mm (±0.78). The orientation of this offset was at an average of 8.63° (±15.28) of supination, reaching from 23° pronation to 32° supination. With these findings, a novel ulnar head prosthesis should have different available stem and head sizes but also have an existing but variable offset between these two elements. A preoperative three-dimensional analysis is due to the high variation of offset orientation highly recommended. These findings might help to better represent the patients natural wrist anatomy in the case of an ulnar head arthroplasty. III.

Background and Objectives: Three-dimensional planning and guided osteotomy utilizing patient-specific instrumentation (PSI) with the contralateral side used as a reference have been proven as effective in the treatment of malunions following complex fractures of the distal radius. However, this approach has not yet been described in relation to fracture reduction of the distal radius. The aim of this study was to assess the technical and logistical feasibility of computer-assisted surgery in a clinical setting using PSI for fracture reduction and fixation. Materials and Methods: Five patients with varied fracture patterns of the distal radius underwent operative treatment with using PSI. The first applied PSI guide allowed specific and accurate placement of Kirschner wires inside the multiple fragments, with subsequent concurrent reduction using a second guide. Results: Planning, printing of the guides, and operations were performed within 5.6 days on average (range of 1–10 days). All patients could be treated within a reasonable period of time, demonstrating good outcomes, and were able to return to work after a follow-up of three months. Mean wrist movements (°) were 58 (standard deviation (SD) 21) in flexion, 62 (SD 15) in extension, 73 (SD 4) in pronation and 74 (SD 10) in supination at a minimum follow-up of 6 months. Conclusions: Three-dimensional planned osteosynthesis using PSI for treatment of distal radius fractures is feasible and facilitates reduction of multiple fracture fragments. However, higher costs must be taken into consideration for this treatment.

Zusammenfassung: Die eigentümliche Form des Kahnbeins ist eine Herausforderung für unser räumliches Vorstellungsvermögen. Deshalb bietet gerade bei der Rekonstruktion von Kahnbeinpseudarthrosen die Computer-Unterstützung unvergleichliche Vorteile: Sie ermöglicht die Erstellung eines echten 3-dimensionalen interaktiven Modells aus CTs, das manipuliert, bearbeitet und bei Bedarf sogar physisch gedruckt werden kann. Der Vergleich mit dem gesunden Kahnbein der Gegenseite analysiert die exakte Fehlstellung und erlaubt damit die Planung einer präzis-anatomischen Wiederherstellung der Kahnbeinform. Schließlich erleichtern computergenerierte patientenspezifischen Instrumente intraoperativ die genaue Umsetzung der Planung. Dieses Vorgehen ermöglicht es, das Kahnbein wesentlich exakter als zuvor wiederherzustellen und damit auch zuverlässiger die gestörte Handgelenkskinematik zu normalisieren. Unterdessen haben wir diese Technik bei der Rekonstruktion von über 50 fehlgestellten Kahnbeinpseudarthrosen erfolgreich angewandt.

3D computer-assisted corrective osteotomy has become the state-of-the-art for surgical treatment of complex bone deformities. Despite available technologies, the automatic generation of clinically acceptable, ready-to-use preoperative planning solutions is currently not possible for such pathologies. Multiple contradicting and mutually dependent objectives have to be considered, as well as clinical and technical constraints, generally requiring iterative manual adjustments. This leads to unnecessary efforts and unbearable clinical costs, hindering also the quality of patient treatment. In this paper, we propose an optimization framework for the generation of ready-to-use preoperative planning solutions in a fully automatic fashion. An automatic diagnostic assessment using patient-specific 3D models is performed for 3D malunion quantification and definition of the optimization parameters. Afterward, clinical objectives are translated into the optimization module, and controlled through tailored fitness functions based on a weighted and multi-staged optimization approach. The optimization is based on a genetic algorithm capable of solving multi-objective optimization problems with non-linear constraints. The framework outputs a complete preoperative planning solution including position and orientation of the osteotomy plane, transformation to achieve the bone reduction, and position and orientation of the fixation plate and screws. A qualitative validation was performed on 36 consecutive cases of radius osteotomy where solutions generated by the optimization algorithm (OA) were compared against the gold standard (GS) solutions generated by experienced surgeons. Solutions were blinded and presented to 6 readers, who voted OA solutions to be better in 55% of the time. The quantitative evaluation was based on different error measurements, showing average improvements with respect to the GS.