Clinical, radiographic, and survivorship analysis of a modular fluted tapered stem in revision hip arthroplasty.

PURPOSE: Modular fluted tapered stems are one of the most commonly used implants in femoral revision surgery. Due to the relative lack of studies on the Restoration modular fluted tapered stem, we conducted a study to evaluate its short- to mid-term clinical, radiographic, and survival outcomes. METHODS: We identified all 45 patients treated with this revision stem at our institution. Five patients did not complete the minimum 2-year follow-up, leaving 40 patients (41 hips) for assessment. Mean follow-up was 5.1 years (range 2-11 years). Clinical outcomes were assessed using the Harris hip score (HHS). Radiographs were evaluated for subsidence and loosening. Kaplan-Meier survival analysis was performed using revision of the stem for any reason as end point. RESULTS: The mean HHS improved from 44.6 points preoperatively to 78.4 points at the most recent follow-up (p < 0.0001). Nonprogressive subsidence occurred in 83% of the hips (mean 2.8 mm; range 1-7 mm). One stem (2.4%) showed progressive subsidence (20 mm) and was considered loose. The most common cause for reoperation was dislocation (three hips, 7.3%). The 10-year survivorship with revision of the stem for any reason as the end point was 93.5% (95% CI, 84.9-100%). CONCLUSION: There was a significant improvement in the HHS and a low likelihood of revision at short- to mid-term follow-up, adding to the current evidence base for use of this implant in revision surgery. A longer follow-up and a larger number of cases are necessary to fully evaluate its role and performance.

A Technique for Dynamic Cervical Magnetic Resonance Imaging Applied to Cervical Spondylotic Myelopathy: A Reliability Study.

STUDY DESIGN: Cross-sectional study. OBJECTIVE: To evaluate morphometric variations of the cervical spine in patients with cervical spondylotic myelopathy (CSM) using a standard technique of dynamic magnetic resonance imaging (MRI), to assess the inter- and intraobserver reliability of measurements of morphometric parameters based on this imaging, and to compare the resulting measurements with those previously published. SUMMARY OF BACKGROUND DATA: Because dynamic factors may contribute to the etiology and severity of CSM, dynamic (flexion-extension) MRI may be useful to better evaluate for spinal stenosis and cord compromise. METHODS: Dynamic cervical MRI was obtained using a standard protocol with the neck in neutral, flexion, and extension positions. The morphometric parameters considered were anterior length of the spinal cord (ALSC), posterior length of the spinal cord (PLSC), spinal canal diameter, and spinal cord width. Two observers analyzed the parameters independently, and the inter- and intraobserver reliabilities were assessed by the intraclass correlation coefficient (ICC). RESULTS: A total of 18 patients were included in the study and all completed the dynamic MRI acquisition protocol. The inter- and intraobserver reliabilities demonstrated "almost perfect agreement" (ICC >0.9, P < 0.001) for ALSC and PLSC in all positions. The spinal canal diameter had inter- and intraobserver reliability classified as "almost perfect agreement" (ICC: 0.83-0.98, P < 0.001 and ICC: 0.90-0.99, P < 0.001, respectively) in all positions. The spinal cord width had inter- and intraobserver reliability classified as "substantial agreement" (ICC: 0.73-0.94, P < 0.001 and ICC: 0.79-0.96, P < 0.001, respectively) in all positions. ALSC and PLSC in neutral, flexion, and extension positions from the present study were significantly greater compared to the measurements previously published (P < 0.001). CONCLUSION: The dynamic MRI protocol presented was safe and may allow a more complete evaluation of variations in the cervical spine in patients with CSM than traditional MRI protocols. The morphometric parameters based on this protocol demonstrated excellent inter- and intraobserver reliabilities. LEVEL OF EVIDENCE: 4.

Dynamic magnetic resonance imaging: preliminary presentation of a technique / Ressonância magnética dinâmica: apresentação preliminar de uma técnica / Resonancia magnética dinámica: presentación preliminar de una técnica

ABSTRACT Objective: To evaluate morphometric variations of the cervical spine in patients with cervical spondylotic myelopathy (CSM) using dynamic magnetic resonance imaging (MRI) in neutral, flexion and extension positions. Methods: This is a prospective study of patients with CSM secondary to degenerative disease of the cervical spine. The morphometric parameters were evaluated using T2-weighted MRI sequences in the sagittal plane in neutral, flexion and extension position of the neck. The parameters studied were the anterior length of the spinal cord (ALSC), the posterior length of the spinal cord (PLSC), the diameter of the vertebral canal (DVC) and the diameter of the spinal cord (DSC). Results: The ALSC and PLSC were longer in flexion than in extension and neutral position, with statistically significant difference between the flexion and extension position. The DVC and the DSC were greater in flexion than in extension and neutral position, however, there was no statistically significant difference when they were compared in the neutral, flexion and extension positions. Conclusion: Dynamic MRI allows to evaluate morphometric variations in the cervical spinal canal in patients with cervical spondylotic myelopathy.

RESUMO Objetivo: Avaliar variações morfométricas da coluna vertebral cervical em pacientes portadores de mielopatia cervical espondilótica (MCE) por meio da ressonância magnética dinâmica nas posições neutra, em flexão e em extensão. Métodos: Este é um estudo prospectivo de pacientes portadores de MCE secundária à doença degenerativa da coluna vertebral cervical. Os parâmetros morfométricos foram avaliados pelas sequências de ressonância magnética ponderadas em T2, no plano sagital em posições neutra, flexão e extensão. Os parâmetros estudados foram o comprimento anterior da medula espinhal (CAME), o comprimento posterior da medula espinhal (CPME), o diâmetro do canal vertebral (DCV) e o diâmetro da medula espinhal (DME). Resultados: O CAME e o CPME foram mais longos em flexão do que nas posições neutra e em extensão, sendo encontrada diferença estatisticamente significativa entre a posição em flexão e extensão. O DCV e o DME foram maiores em flexão do que nas posições neutra e em extensão, no entanto não foi encontrada diferença estatisticamente significativa quando comparados nas posições neutra, em flexão e em extensão. Conclusão: O exame de ressonância magnética dinâmica permite avaliar as variações morfométricas do canal vertebral cervical em pacientes portadores de mielopatia cervical espondilótica.

RESUMEN Objetivo: Evaluar las variaciones morfométricas de la columna cervical en pacientes con mielopatía cervical espondilótica (MCE) mediante resonancia magnética dinámica en la posición neutra, en flexión y extensión. Métodos: Se trata de un estudio prospectivo de pacientes con MCE secundaria a la enfermedad degenerativa de la columna cervical. Los parámetros morfométricos fueron evaluados en las secuencias ponderadas en T2 en el plano sagital en la posición neutra, en flexión y extensión de la resonancia magnética. Los parámetros estudiados fueron la longitud anterior de la médula espinal (LAME), la longitud posterior de la médula espinal (LPME), el diámetro del canal espinal (DCE) y el diámetro de la médula espinal (DME). Resultados: La LAME y la LPME fueron más largas en flexión que en las posiciones neutra y en extensión, con diferencia estadísticamente significativa entre la posición en flexión y extensión. El DME y el DCE fueron mayores en flexión que en extensión y la posición neutra, sin embargo no hubo diferencia estadísticamente significativa cuando se compararon en la posición neutral, en flexión y extensión. Conclusión: El examen de resonancia magnética dinámica permite evaluar los cambios morfométricos en el canal espinal cervical en pacientes con mielopatía cervical espondilótica.

Detecting early biomechanical effects of zoledronic Acid on femurs of osteoporotic female rats.

Aim. To investigate the biomechanical effects of zoledronic acid (ZA) on femurs of female osteoporotic rats after follow-up periods of 9 and 12 months. Methods. Eighty female Wistar rats were prospectively assessed. At 60 days of age, the animals were randomly divided into two groups: bilateral oophorectomy (O) (n = 40) and sham surgery (S) (n = 40). At 90 days of age, groups O and S were randomly subdivided into four groups, according to whether 0.1 mg/kg of ZA or distilled water (DW) was intraperitoneally administered: OZA (n = 20), ODW (n = 20), SZA (n = 20), and SDW (n = 20). The animals were sacrificed at 9 and 12 months after the administration of the substances, and then their right femurs were removed and analyzed biomechanically. Axial compression tests that focused on determining the maximum load (N), yield point (N), and stiffness coefficient (N/mm) of the proximal femur were performed in the biomechanical study. Results. ZA significantly increased the maximum load and yield point, reducing the stiffness coefficient concerning the oophorectomy status and follow-up period. Conclusion. Zoledronic acid, at a dose of 0.1 mg/kg, significantly increased the maximum loads and yield points and reduced the stiffness coefficients in the femurs of female rats with osteoporosis caused by bilateral oophorectomy.