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Introduction: Crystalline lens overshooting refers to a situation in which the lens momentarily shifts too much from its typical location immediately after stopping the rotational movement of the eye globe. This movement can be observed using an optical technique called Purkinje imaging.Methods: In this work, an experimental setup was designed to reproduce this effect ex vivo using a fresh porcine eye. The sample was rotated 90° around its centroid using a high-velocity rotation stage, and the Purkinje image sequences were recorded, allowing us to quantify the overshooting effect. The numerical part of the study consisted of developing a computational model of the eye, based on the finite element method, that allowed us to understand the biomechanical behavior of the different tissues in this dynamic scenario. A 2D fluid–structure interaction model of the porcine eye globe, considering both the solid parts and humors, was created to reproduce the experimental outcomes.Results: Outputs of the simulation were analyzed using an optical simulation software package to assess whether the mechanical model behaves optically like the real ex vivo eye. The simulation predicted the experimental results by carefully adjusting the mechanical properties of the zonular fibers and the damping factor.Conclusion: This study effectively demonstrates the importance of characterizing the dynamic mechanical properties of the eye tissues to properly comprehend and predict the overshooting effect.

Purpose: The goal of this study was to review available literature on periprosthetic shoulder fractures to evaluate epidemiology, risk factors and support clinical decision-making regarding diagnostics, preoperative planning, and treatment options. Methods: Two authors cross-checked the PubMed and Web of Science medical databases. The inclusion criteria were as follows: original human studies published in English, with the timeframe not limited, and the following keywords were used: ‘periprosthetic shoulder fracture,’ ‘total shoulder arthroplasty periprosthetic fractures,’ ‘total shoulder arthroplasty fracture,’ and ‘total shoulder replacement periprosthetic fracture.’ Seventy articles were included in the review. All articles were retrieved using the aforementioned criteria. Results: The fracture rate associated with total shoulder arthroplasty varied between 0 and 47.6%. Risk factors for periprosthetic fractures were female gender, body mass index < 25 kg/m2, smoking, rheumatoid arthritis, and Parkinson’s disease. The most commonly used classification is the Wright and Coefield classification. Periprosthetic fractures can be treated both, conservatively and operatively. Conclusion: Periprosthetic fracture frequency after shoulder arthroplasty ranges from 0 to 47.6%. The most common location of the fracture is the humerus and most commonly occurs intraoperatively. The most important factor influencing treatment is stem stability. Fractures with stem instability require revision arthroplasty with stem replacement. Fractures with a stable stem depending on the location, displacement and bone stock quality can be treated both conservatively and operatively. For internal fixation plates with cables and screws are most commonly used.

Objective To validate with a prospective study a decision-supporting coding system for the surgical approach for multilevel degenerative cervical myelopathy. Methods Ten cases were presented on an internet platform, including clinical and imaging data. A single-approach (G1), a choice between 2 (G2), or 3 approaches (G3) were options. Senior and junior spine surgeons analyzed 7 parameters: location and extension of the compression of the spinal cord, C-spine alignment and instability, general morbidity and bone diseases, and K-line and multilevel corpectomy. For each parameter, an anterior, posterior, or combined approach was suggested. The most frequent letter or the last letter (if C) of the resulting 7-letter code (7LC) suggested the surgical approach. Each surgeon performed 2 reads per case within 8 weeks. Results G1: Interrater reliability between junior surgeons improved from the first read (κ = 0.40) to the second (κ = 0.76, p < 0.001) but did not change between senior surgeons (κ = 0.85). The intrarater reliability was similar for junior (κ = 0.78) and senior (κ = 0.71) surgeons. G2: Junior/senior surgeons agreed completely (58%/62%), partially (24%/23%), or did not agree (18%/15%) with the 7LC choice. G3: junior/senior surgeons agreed completely (50%/50%) or partially (50%/50%) with the 7LC choice. Conclusion The 7LC showed good overall reliability. Junior surgeons went through a learning curve and converged to senior surgeons in the second read. The 7LC helps less experienced surgeons to analyze, in a structured manner, the relevant clinical and imaging parameters influencing the choice of the surgical approach, rather than simply pointing out the only correct one.

The fixation of type 2 odontoid fractures poses significant challenges in the elderly population due to coexistent osteoporosis and communition resulting in a high failure rate with conventional anterior screw fixation. Two elderly patients with unstable odontoid peg fractures and coexistent osteoporosis were treated with stentoplasty and anterior odontoid screw fixation. Additional anterior transarticular C1–2 screws were placed to address C1–2 instability. Both patients made an uneventful clinical recovery. One of the anterior C1–2 screws loosened due to the poor purchase in the osteoporotic bone in one patient. This did not affect the final outcome, and both the patients demonstrated maintained reduction and good alignment of odontoid peg after 2 years of follow-up. There was no intraoperative cement leak, pseudoarthrosis, or loss of reduction. Stentoplasty coupled with the anterior odontoid screw is a safe technique that can provide a biomechanically sound fixation of type 2 odontoid fractures in the presence of osteoporosis and significant communition.

Pressure injuries (PIs) are a common surgical complication. The authors identified critical design requirements and developed an appropriate product design specification for a device to monitor PIs during surgery.

Category: Basic Sciences/Biologics Introduction/Purpose: A scientifically sound validated foot and ankle specific outcome measure for different European languages is still missing. Indeed, language-specific cross cultural validation in other languages than English is largely absent. Some outcome measures were validated for specific pathologies such as hallux valgus, ankle arthritis or flatfoot. The European Foot and Ankle Society (EFAS) established in 2013 a Score Committee to develop, validate, and publish a new score, the “EFAS Score”, which is not specific for single pathologies for different European languages. The principal aim of this project was to develop and validate the EFAS Score simultaneously for different European languages. Methods: The EFAS Score was developed and validated in three stages: 1) item (question) identification, 2) item reduction and scale exploration, 3) confirmatory analyses and responsiveness. The following score specifications were chosen: scale/subscale (Likert 0-4), questionnaire based, outcome measure, patient related outcome measurement. For stage 3, data were collected pre- operatively and post-operatively at a minimum follow-up of 3 months and mean follow-up of 6 months. Item reduction, scale exploration, confirmatory analyses and responsiveness were executed using analyses from classical test theory and item response theory. Results: Stage 1 resulted in 31 general and 7 sports related questions. In Stage 2, a 6-item general EFAS Score was constructed using English, German, French and Swedish language data. In Stage 3, internal consistency of the scale was confirmed in seven languages: the original four languages, plus Dutch, Italian and Polish (Cronbach’s Alpha >0.86 in all language versions). Responsiveness was good, with moderate to large effect sizes in all languages, and significant positive association between the EFAS Score and patient-reported improvement. No sound EFAS Sports Score could be constructed. Conclusion: The multi-language EFAS Score has been successfully validated for orthopaedic foot and ankle surgery populations incorporating a wide variety of foot and ankle pathologies, including language-specific validation in seven languages so far (English, German, French, Swedish, Dutch, Italian, Polish). Validation for other languages (Danish, Finnish, Norwegian, Portuguese, Spanish, Turkish) is in progress. All validated score versions are freely available at www.efas.co .

Category: Trauma Introduction/Purpose: The genetic Lauge-Hansen classification is considered to provide a link between mechanism of ankle injury and resulting fracture morphology. In this study, we addressed the question of agreement between the mechanism of the fracture as postulated by the Lauge-Hansen classification and mechanism reported by the patient in rotational ankle fractures. Understanding of the actual mechanisms of ankle fracture may guide treatment decisions. Methods: Of 110 screened patients with acute malleolar fractures, 78 were able to provide information on their fracture mechanism and were included in the study. The study group consisted of 43 women and 35 men with a mean age of 47.8 (range 19.5-88.4) years. Patients were asked to describe the direction of deformation with primary question being pronation and supination as demonstrated by the examiner. As hyperplantarflexion and hyperdorsiflexion has been spontaneously reported by the patients, these directions were added to the analysis. Radiographs were analyzed according to Lauge-Hansen classification and compared with fracture mechanisms reported by the patients. Results: The majority (35/78 = 44.8%) of patients reported pronation as their fracture mechanism, 27 (34.6%) patients reported supination, 15 (19.2%) patients reported hyperplantarflexion (3 pure, one combined with pronation and 11 combined with supination), and 1 patient reported hyperdorsiflexion combined with pronation. Radiographs revealed 61 supination-external rotation (79%), 1 supination-adduction (1.3%), 14 pronation-external rotation (18%), 1 pronation-abduction (1.3%) fractures. One x-ray was unclassifiable with the Lauge-Hansen classification. The patient reported mechanisms were in concordance with the mechanism deducted from the x-rays in 49% of cases. Only 17% of patients who recalled a pronation trauma actually had radiographs classified as pronation fractures while 76% of patients who recalled a supination trauma were also radiographically classified as having sustained supination type fractures. Conclusion: The Lauge-Hansen classification should be used with caution for determining the actual mechanism of injury as it was able to predict the patient reported fracture mechanism in less than 50% of cases. A substantial percentage of fractures appearing radiographically as supination type injuries may have been actually produced by a pronation fracture mechanism.

Category: Trauma Introduction/Purpose: The anatomy of the syndesmosis is variable, yet little is known on the correlation between morphology and the risk of syndesmotic disruption and malreduction with operative fixation. The study aims at (1) comparing the bony anatomy of the syndesmosis in patients who sustained a high fibular fracture with syndesmosis disruption and that of the non-injured population and (2) at identification of certain anatomical features correlating with syndesmotic malreduction. Methods: For the first research question, the CT examinations of 75 patients who sustained a high fibular fracture with syndesmosis disruption and a control group of 75 patients with unrelated foot problems and without ankle pathology were compared. For the second research question, the bilateral postreduction ankle CTs of 72 patients were analyzed. Incisura depth, fibular engagement into the incisura and incisura rotation (Figure) of the injured patients were compared with those of uninjured controls and correlated with degree of syndesmotic malreduction in the coronal plane, sagittal plane, and rotational malreduction. Results: With the median values of the control group as cutoff there were 71% shallow, 71% disengaged and 77% retroverted syndesmoses in the injury group. The differences between the groups were statistically significant for every measure (P< .002 to P> .0001). Clinically relevant syndesmosis malreduction in coronal plane, sagittal plane and rotation affected 8.3; 27.8; and 19.4% of, patients, respectively. The syndesmoses with a deep incisura and the fibula not engaged into the tibial incisura were at risk of overcompression (P< .05). Syndesmosis with an anteverted incisura were at risk of anterior fibular translation and those with a retroverted incisura were at risk of posterior fibular translation (P< .05). Conclusion: Patients with a shallow, disengaged and retroverted bony configuration of the tibial incisura at the syndesmosis are overrepresented among patients with syndesmotic disruption. Intraoperative overcompression of the syndesmosis is significantly more common in patients with a deep and less engaged incisura. Anteversion of the incisura correlates with anterior displacement of the fibula while retroversion of the incisura is correlated with posterior fibular displacement. Knowledge of the individual incisura morphology could be helpful when planning and performing reduction of an unstable syndesmosis.