Biomechanical performance of talon cannulated compression device in pauwels type III fractures: a comparative study.

INTRODUCTION: Pauwels Type III fractures are unstable and frequently treated with cannulated screws (CS) or dynamic hip screws (DHS). The newly developed talon-cannulated compression devices (TCCD) have the potential to provide rotational stability, mainly through their talon. The study investigates whether TCCD has mechanical advantages over conventional screws or can be as stable as DHS in a reverse triangle configuration for an unstable femoral neck fracture. MATERIAL AND METHODS: After creating a standard Pauwels Type III unstable femoral neck fracture in 36 synthetic femur bones in cortical/hard cancellous bone density, 18 were reserved for dynamic-static tests, and 18 were used for torsional tests. Each group containing 18 synthetic bones was divided into three groups to apply three different fixation materials (CS, DHS, and TCCD), with six models in each group. The displacement amounts after dynamic-static tests were measured using the AutoCAD program according to the reference measurement criteria. During the dynamic tests, a series of photographs were taken. During the static tests, the beginning and post-test photographs were taken. Finally, torsional tests were performed until implant failure occurred in the synthetic femur. RESULTS: In static axial loading tests, TCDD was found to be statistically superior to conventional CS in AL-BL distance (p = 0,014) and CL distance (p = 0,013) measurements, and there was no significant difference between the other groups. There was no significant difference between all groups in dynamic axial compression tests in any points of interest. In torsional tests, TCCD outperformed cannulated screws in stiffness (p = 0,001) and maximum torque (p = 0,001) categories, and they provided statistically significant superiority to DHS in yield torque (p<0,001) category. CONCLUSIONS: Biomechanically, TCCD predominates conventional cannulated screws in femoral neck fractures. TCCD also has superior torsional properties than DHS in the yield torque category. Therefore, TCCD could be the implant of choice for unstable femoral neck fractures.

Combined clinical test and magnetic resonance imaging have similar diagnostic values in the diagnosis of subscapularis tear.

PURPOSE: The aim of the present study was to compare the diagnostic values of clinical tests and magnetic resonance imaging (MRI) which used for the diagnosis of subscapularis (SSc) tears in the patients who underwent arthroscopic rotator cuff surgery. METHODS: Two-hundred and nine consecutive patients who underwent arthroscopic rotator cuff surgery between 2015 and 2019 were analyzed. The lift-off test, belly-press test and bear-hug test were performed preoperatively. 1.5 T MRI scans of all patients were evaluated for SSc integrity. The diagnostic values of both clinical tests and MRI were calculated. SSc tears were graded according to Fox and Romeo. Arthroscopic findings were used as the gold standard for diagnosis of SSc tears. RESULTS: There were 54 SSc tears accounting for an prevalence of 29%. The BHT showed the greatest sensitivity for both type II-II-IV (73.3%) and all types of (68.5%) SSc tears. The sensitivity and specificity of the combined test and MRI were 91.1-87.2% and 93.3-90.8% in Type II-III-IV SSc tears, respectively, and 81.5-88.6% and 88.9-94.7% in all SSc tears, respectively. There were no statistically significant difference between combined test and MRI in terms of sensitivity and specificity (n.s.). CONCLUSION: The present study is the first that compared both clinical tests and MRI with arthroscopic findings in terms of sensitivity and specificity in the same patient group. A combination of clinical tests increases their diagnostic values and shows similar sensitivity and specificity as MRI. LEVEL OF EVIDENCE: I.