Proper understanding of the complex geometric shape of the talus bone is important for the design of generic talar body prosthetics and restoration of the proper ankle joint function after surgery. To date, all talus implants have been patient-specific with the limitation that complex computer modeling is required to produce a mirrored image from the unaffected opposite side followed by machining a patient-specific prosthesis. To develop an "off-the-shelf" non-custom talar prosthesis, it is important to perform a thorough investigation of the geometric shape of the talus bone. This article addresses the applicability of a scaling approach for investigating the geometric shape and similarity of talus bones. This study used computed tomography scan images of the ankle joints of 27 different subjects to perform the analysis. Results of the deviation analyses showed that the deviation in the articulating surfaces of the talus bones was not excessive in terms of talus size. These results suggest that a proposed range of five implant sizes is possible. Finally, it is concluded that the talus bones of the ankle joints are geometrically similar, and a proposed range of five implant sizes will fit a wide range of subjects. This information may help to develop generic talus implants that might be applicable to patients with a severe talus injury.
ObjectiveThe main object of this study was to use a geometric morphometric approach to quantify the left-right symmetry of talus bones. MethodsAnalysis was carried out using CT scan images of 11 pairs of intact tali. Two important geometric parameters, volume and surface area, were quantified for left and right talus bones. The geometric shape variations between the right and left talus bones were also measured using deviation analysis. Furthermore, location of asymmetry in the geometric shapes were identified. ResultsNumerical results showed that talus bones are bilaterally symmetrical in nature, and the difference between the surface area of the left and right talus bones was less than 7.5%. Similarly, the difference in the volume of both bones was less than 7.5%. Results of the three-dimensional (3D) deviation analyses demonstrated the mean deviation between left and right talus bones were in the range of -0.74 mm to 0.62 mm. It was observed that in eight of 11 subjects, the deviation in symmetry occurred in regions that are clinically less important during talus surgery. ConclusionsWe conclude that left and right talus bones of intact human ankle joints show a strong degree of symmetry. The results of this study may have significance with respect to talus surgery, and in investigating traumatic talus injury where the geometric shape of the contralateral talus can be used as control.Cite this article: Bone Joint Res 2014;3:139–45.
Type 1 supracondylar humerus (SCH) fractures tend to heal well when immobilized by above-elbow casting or long-arm splinting. There is no consensus as to whether one treatment method is more effective than the other for this injury. The purpose of this study was to compare the radiographic and functional outcomes of long-arm splinting and above-elbow casting as the definitive treatment for children with type 1 SCH fractures. The study was set up as a randomized controlled non-inferiority trial. Patients between three and 12 years old presenting with a type 1 SCH fracture were randomized into splint or cast groups, or an observational arm. Baumann’s angle, functional assessment scores, and Flynn’s criteria score were measured at initial injury and at six months post-injury. In total, 34 patients were enrolled in the study with 13 in the randomized arm and 21 in the observational arm. Due to lack of follow-up data at 6 months post-injury, five splint patients and 10 cast patients were included in the final cohort for data analysis. The average change in Baumann’s angle at 6-month follow-up was 3° or less for each treatment arm. The splint group obtained excellent Flynn’s criteria scores while the cast group reported good and excellent scores. Complications reported in the splint group included device breakdown, a conversion to above-arm cast, and significant itchiness. Preliminary findings suggest functional and radiological outcomes with splinting are non-inferior to casting; however, a larger sample size is required to more accurately compare the two modalities. This study was registered with the U.S. National Institutes of Health (ClinicalTrials.gov, #NCT01912365).
Background: Ankle fractures are among the most common injuries encountered by orthopedic surgeons, with an incidence ranging from 71 to 187 per 100 000 people. Few studies have reliably investigated injuries involving isolated fractures of the distal fibula below the level of the ankle syndesmosis. Therefore, this study details on the patient-reported outcomes of nonoperatively managed isolated infrasyndesmotic fibula (ISF) fractures with a minimum 3-year follow-up. Methods: A retrospective population-based cohort study was undertaken across all emergency departments serving a major urban population. Among 159 consecutive patients meeting inclusion criteria, 108 agreed to participate. Clinical information, functional outcomes, and radiographic measurements were collected from electronic medical records and 3 validated outcome measures: the American Academy of Orthopaedic Surgeons (AAOS) Foot & Ankle Scale (FAS), the AAOS Shoe-Comfort Scale (SCS), and a general questionnaire. Results: An incidence of 22 ISF fractures per 100 000 people/year was found with FAS (91.2 ± 12.9) and SCS scores (76.8 ± 27.7), similar to reported population norms. Approximately 40% of patients (n = 43) reported continuing symptoms including pain (81.8%), stiffness (68.1%), and/or instability (39.0%). Less than 13% (n = 14) reported “severe” disabilities, and no patients required operative intervention within the follow-up period. Less-favorable outcomes were reported among work-related injuries, female patients, and “avulsion-type” fractures less than 10 mm in height ( P < .01). No relationships were identified between age, degree of articular-incongruity, fracture-displacement, and self-reported outcomes. Conclusions: The majority of patients with nonoperatively managed ISF fractures reported good-to-excellent early functional outcomes. Less-favorable outcomes were reported among work-related injuries, female patients, and “avulsion-type” fractures. Level of Evidence: Level III, comparative series.
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