OBJECTIVETo assess the optimal configuration of double-screw fixation for subtalar arthrodesis using finite element analysis.

METHODSThree-dimensional finite element double-screw models of subtalar arthrodesis were reconstructed using Mimics 13.0, Geomagic 10.0 and solid works software based on the 3-D images of the volunteer's right foot. The external and internal rotation torques of 4 N·m were applied, and the micromotion at the bone-to-bone interface were measured to evaluate the initial stability of subtalar arthrodesis.

RESULTSA neck screw plus an anterolateral dome screw was the most stable model. The peak micromotion at the fusion site of this fixation configuration were 41.67mnplus;0.49 and 42.64mnplus;0.75 µm in response to the respectively. A neck screw plus a posteromedial dome screw was the least stable model, with peak micromotion at the bone-to-bone interface of 61.76mnplus;1.00 and 62.32mnplus;0.90 µm, respectively.

CONCLUSIONA neck screw plus an anterolateral dome screw is the best fixation configuration while a neck screw plus a posteromedial screw provides the least stability of subtalar arthrodesis. Three-dimensional finite element models allow effective preoperative planning of the screw number and placement.

Adult ; Ankle ; diagnostic imaging ; Arthrodesis ; methods ; Bone Screws ; Finite Element Analysis ; Humans ; Imaging, Three-Dimensional ; Internal Fixators ; Models, Anatomic ; Software ; Subtalar Joint ; surgery ; Tomography, X-Ray Computed

Objective:To study the clinical characteristics and death risk factors of the patients with fall-related injuries in parts of Kashgar Prefecture during 2019-2020.Methods:The clinical data were retrospectively analyzed of the 894 patients with fall-related injuries who had been admitted to Department of Trauma Center, The First People's Hospital of Kashgar Prefecture, Xinjiang Uygur Autonomous Region from January 2019 to December 2020. Recorded were the patient's gender, age, location of fall, month of fall, fall height, major injury site, injury severity score (ISS) and Glasgow score (GCS). The clinical characteristics and death risk factors of the fall patients were analyzed.Results:Of the 894 patients, 72.3%(646/894) were male and 86.9%(777/894) fell from a height from 1 to 6 meters. Their ages ranged mainly from 15 to 59 years old (74.3%, 664/894). Home was the most frequent site for falls (60.2%, 538/894) and the patients who fell in summer months (from June to August) were the most (32.3%, 289/894). Twenty-one patients (2.3%, 21/894) died. There were significant differences in the major injury site, blood transfusion, ISS score and GCS score between the dead and survival patients ( P<0.05). The multivariate logistic regression analysis showed that the injury to the head, face and neck [ OR=10.936, 95% CI: 1.177 to 101.627, P=0.035] and GCS score ≤12 [ OR=5.640, 95% CI: 2.658 to 11.968, P< 0.001] were the death risk factors for the patients with fall-related injuries in parts of Kashgar Prefecture during 2019-2020. Conclusions:In the patients with fall-related injuries in parts of Kashgar Prefecture during 2019-2020, males aged from 15 to 59 years old were the high-risk group of falls. Months with a high incidence of falls were from June to August. The fall patients with injuries to the head, face and neck and with a GCS score of ≤12 were at a high risk of death.