Computer assisted surgery (CAS) is used in trauma surgery to reduce radiation and improve accuracy but it is time consuming. Some trials for navigation in small bone fractures were made, but they are still experimental. One major problem is the fixation of the dynamic reference base for navigation. We evaluated the benefit of a new image based guidance-system (Surgix®, Tel Aviv, Israel) for fracture treatment in scaphoid bones compared to the conventional method without navigation. The system consists of a workstation and surgical devices with embedded radio opaque markers. These markers as well as the object of interest must be on the same C-arm shot. If a tool is detected in an image by the attached workstation additional information such as trajectories are displayed in the original fluoroscopic image to serve the surgeon as aiming device. The system needs no referencing and no change of the workflow. For this study 20 synthetic hand models (Synbone®, Malans, Switzerland) were randomised in two groups. Aim of this study was a central guide-wire placement in the scaphoid bone, which was blindly measured by using postoperative CT-scans. Significant distinctions related to the duration of surgery, emission of radiation, radiation dose, and trials of guide-wire positioning were observed. By using the system the surgery duration was with 50 % shortened (p = 0.0054) compared to the conventional group. One reason might be the significant reduction of trials to achieve a central guide-wire placement in the bone (p = 0.0032). Consequently the radiation exposure for the surgeon and the patient could be shortened by reduction of radiation emission (p = 0.0014) and radiation dose (p = 0.0019). By using the imaged based guidance system a reduction of surgery duration, radiation exposure for the patient and the surgeon can be achieved. By a reduced number of trials for achieving a central guide-wire position the risk of weakening the bone structure can be minimised as well by using the system. The system seems helpful where navigation is not applicable up to now. The surgical workflow does not have to be chanced

The internal fixation of scaphoid bone fractures remains technically difficult due to the size of the bone and its three- dimensional shape. Early rigid fixation, e.g with a screw, has been shown to support good functional outcome. In terms of stability of the fracture, biomechanical studies have shown a superior result with central screw placement in the scaphoid in comparison with an eccentric position, which can lead to delayed or non-union. Image-based navigation could be helpful for these cases. The main limitation of reference-based navigation systems is their dependence on fixed markers like used in modern navigation systems. Therefore it is limited in treatment of small bone fractures. In former experimental studies 20 artificial hand specimens were randomised into two groups and blinded with polyurethane foam: 10 were treated conventionally and 10 were image guided. For trajectory guidance a reduction of duration of surgery, radiation exposure and perforation rate compared to the conventional technique could be found. Accuracy was not improved by the new technique. The purpose of this study was to identify the possible advantages of the new guidance technique in a clinical setting. In this prospective, non-randomised case series we tested the feasibility of the system into the accommodated surgical workflow. There was no control group. Three cases of scaphoid fractures were included. All of the patients were treated with a cannulated screw following K-wire placement via the percutaneous volar approach described. In addition, length measurements and screw sizes were determined using special features of the system. The performing surgeon and two attending assistant doctors (one assisting the surgical procedure, one handling the guidance system) had to rate the system following each procedure via a user questionnaire. They had to rate the system's integration in the workflow and its contribution to the success of the surgical procedure in percentages (0 %: totally unsuccessful; 100 %: perfect integration and excellent contribution). All of the clinical procedures were performed by the same surgeon. The surgeons rated the system's contribution and integration as very good (91 and 94 % of 100 %). No adverse event occurred. An average of 1.3 trials ± 0.6 (1; 2) was required to place the K-wire in the fractured scaphoid bone. The dose-area product was 19 cGycm2 ± 3 (16; 22). The mean incision until suture time was 36.7 min ± 5.7 (30; 40). For clinical cases, the system was integrated and rated as very helpful by users. The system is simple and can be easily integrated into the surgical workflow. Therefore it should be evaluated further in prospective clinical series

Scaphoid non-union results the typical humpback deformity, pronation of the distal fragment, and a bone defect in the non-union site with shortening. Bone grafting, whether open or arthroscopic, relies on fluoroscopic and direct visual assessment of reduction. However, because of the bone defect and irregular geometry, it is difficult to determine the precise width of the bone gap and restore the original bone length, and to correct interfragmentary rotation. Correction of alignment can be performed by computer-assisted planning and intraoperative guidance. The use of computer navigation in guiding reduction in scaphoid non-unions and displaced fractures has not been reported. Objective. We propose a method of anatomical reconstruction in scaphoid non-union by computer-assisted preoperative planning combined with intraoperative computer navigation. This could be done in conjunction with a minimally invasive, arthroscopic bone grafting technique. Methods. A model consisting of a scaphoid bone with a simulated fracture, a forearm model, and an attached patient tracker was used. 2 titanium K-wires were inserted into the distal scaphoid fragment. 3D images were acquired and matched to those from a computed tomography (CT) scan. In an image processing software, the non-union was reduced and pin tracts were planned into the proximal fragment. The K-wires were driven into the proximal fragment under computer navigation. Reduction was assessed by direct measurement. These steps were repeated in a cadaveric upper limb. A scaphoid fracture was created and a patient tracker was inserted into the radial shaft. A post-fixation CT was obtained to assess reduction. Results and Discussion. In both models, satisfactory alignment was obtained. There were minimal displacement and articular stepping, and scaphoid length was restored with less than 1mm discrepancy. This study demonstrated that an accurate reduction of the scaphoid in non-unions and displaced fractures can be accurately performed using computed navigation and computer-assisted planning. It is the first report on the use of computer navigation in correction of alignment in the wrist

Using inaccurate quotations can propagate misleading information, which might affect the management of patients. The aim of this study was to determine the predictors of quotation inaccuracy in the peer-reviewed orthopaedic literature related to the scaphoid. We randomly selected 100 papers from ten orthopaedic journals. All references were retrieved in full text when available or otherwise excluded. Two observers independently rated all quotations from the selected papers by comparing the claims made by the authors with the data and expressed opinions of the reference source. A statistical analysis determined which article-related factors were predictors of quotation inaccuracy. The mean total inaccuracy rate of the 3840 verified quotes was 7.6%. There was no correlation between the rate of inaccuracy and the impact factor of the journal. Multivariable analysis identified the journal and the type of study (clinical, biomechanical, methodological, case report or review) as important predictors of the total quotation inaccuracy rate.

We concluded that inaccurate quotations in the peer-reviewed orthopaedic literature related to the scaphoid were common and slightly more so for certain journals and certain study types. Authors, reviewers and editorial staff play an important role in reducing this inaccuracy.