Hindfoot motion through helical axis image-based on dynamic CT scan using an original simulated weightbearing device.

BACKGROUND: Determining the treatment of subtalar joint (STJ) instability requires a better understanding of the biomechanical principles underlying the condition and, a proper diagnosis. This study aimed to analyze "in vivo" the range of motion of the subtalar joint (STJ) measured on two (2D) and three dimensions (3D) image-based on CT Scan using an original device that maintains a simulated weightbearing. The secondary goal was to correlate the 2D and 3D measurement. METHODS: An observational study was conducted, using an original Dynamic Simulated Weightbearing Device. Asymptomatic ankles were included. Each subject underwent a CT scan under mechanical stress and simulated weightbearing conditions, maintaining maximum eversion and inversion hindfoot positions. The images were obtained, combining both inversion and eversion positions in a single model, which allows for to calculation of the motion vector as well as the helical axis. The helical axis (rotation angle and translation distance), subtalar tilt, anterior drawer, and, subtalar and calcaneocuboid uncoverage were the determinations. RESULTS: Forty asymptomatic ankles were included. The average range of motion of the STJ amounts to 31.5° ± 9.1° of rotation and 1.56 ± 0.8 mm of translation distance. The anterior drawer and subtalar uncoverage variables were statistically significantly related to each other (r = 0.57; P = 0.00001). However, these 2-D measured variables were not related to kinematic measures of rotation through the helical axis (3D) (p = 0.14; p = 0.19) CONCLUSIONS: The average range of motion of the STJ amounts to 31.5° ± 9.1° of rotation and 1.56 ± 0.8 mm of translation distance. We found no significant correlation between 2D and 3D measurements. In our opinion, the rotation angle and translation distance should be considered the most accurate measurements and should be calculated on every STJ instability for comparison with the asymptomatic population LEVEL OF EVIDENCE: Observational study.

Luxación inveterada anterior de hombro tratada mediante artroplastia invertida en paciente anciana. A propósito de un caso / Anterior inveterate dislocation of the shoulder in an elderly patient treated by reverse arthroplasty. Case report

Objetivos: se presenta un caso de luxación anterior inveterada de hombro derecho y su tratamiento mediante implantación de prótesis invertida. Material y métodos: Paciente de 69 años que se diagnostica de luxación anterior inveterada de hombro con antecedentes de luxación anteroinferior postraumática 6 meses antes, tratada conservadoramente. Mediante pruebas de imagen se objetivó la existencia de un voluminoso Bankart óseo, así como rotura masiva del manguito rotador. Se optó por realizar cirugía abierta, reconstruyendo el defecto glenoideo con autoinjerto y osteosíntesis mediante tornillos canulados. Se decidió tratamiento definitivo en un mismo acto quirúrgico con la implantación de prótesis invertida con técnica de aumentación del offset. Resultados: Se consiguió una adecuada congruencia y estabilidad articular con excelente función global a los 6 meses de la intervención, libre de dolor. Conclusiones: La luxación anterior inveterada de hombro es una patología infrecuente en la práctica clínica habitual de la que no se dispone mucha información en la literatura. El tratamiento quirúrgico mediante artroplastia invertida de hombro puede ser adecuado para el tratamiento de la misma, debido a los buenos resultados clínicos, radiológicos y funcionales que proporciona

Objective: We present the case of an inveterate anterior dislocation of the glenohumeral joint and following treatment by reverse artrhoplasty. Materials and methods: 69 years-old female patient, diagnosed of anterior inveterate dislocation of the shoulder with a history of traumatic dislocation, treated conservatively 6 months earlier. The existence of a large bony Bankart and a massive rotator cuff tear was observed by imaging studies. Open surgery was performed,filling the glenoid defect with autograft and internal fixation using cannulated screws. Final treatment was decided in the same surgery performing bony increased-offset reverse shoulder arthroplasty (BIO-RSA) technique. Results: proper articular congruency and painfree stability with excellent overall function at 6months after surgery was achieved. Conclusions: The anterior inveterate glenohumeral dislocation is a rare condition in clinical practice from which much information is not available in the literature. Surgical treatment by reverse shoulder arthroplasty may be an appropriate therapeutic option to treat it, due to the good clinical, radiological and functional results it provides