Three-year clinical and radiological results of a cruciate-retaining type of the knee prosthesis with anatomical geometry developed in Japan

Background The FINE total knee was developed in Japan and clinical use began in 2001. It has unique design features, including an oblique 3o femorotibial joint line that reproduces anatomical geometry. Although 20 years have passed since the FINE knee was clinically used for the first time in Japan, a formal clinical evaluation including patient-reported and radiographic outcomes has not been undertaken. Methods A total of 175 consecutive primary cruciate-retaining (CR)-FINE total knee arthroplasties (TKAs) at our hospital between February 2015 and March 2017 were included in this study. Three years postoperatively, range of motion (ROM), Knee Society Score (KSS), Knee Injury and Osteoarthritis Outcome Score (KOOS) and Forgotten Joint Score (FJS) were recorded and compared with preoperative scores. Radiographic analyses including mechanical alignment, component alignment, and incidence of radiolucent lines also were undertaken based on the radiographs 3 years postoperatively. Results One-hundred twenty-two knees (70%) were available for 3-year follow-up data using KOOS, except for the sports subscale. Postoperative KOOS-symptom, −pain and -ADL were > 85 points, but KOOS-sports, −QOL and FJS were less satisfactory. ROM, KSS and all the subscales of KOOS were significantly improved compared with preoperative scores. Postoperative mean FJS was 66 and was significantly correlated with all the subscales of KOOS, but not with postoperative ROM. Radiolucent lines ≧1 mm wide were detected in five knees (4.1%). There were no major complications needing revision surgeries. Conclusions Patient-reported outcomes (PROs) for symptoms, pain and ADL after the CR-FINE TKA were generally improved, but those for sports, QOL and FJS were improved less. The incidence of radiolucent lines was rare but detected around the femoral components. With the mid- to long-term follow-up, improvements of surgical technique will be necessary to achieve better PROs from patients receiving the FINE knee.

Three-Year Clinical Results of a Cruciate-Retaining Type of the Knee Prosthesis with Anatomical Geometry Developed in Japan

Background: The FINE total knee was developed in Japan and clinical use began in 2001. It has unique design features, including an oblique 3o femorotibial joint line that reproduces anatomical geometry. Although 20 years have passed since the FINE knee was clinically used for the first time in Japan, a formal clinical evaluation including patient-reported and radiographic outcomes has not been undertaken.Methods: A total of 175 consecutive primary cruciate-retaining (CR)-FINE total knee arthroplasties (TKAs) at our hospital between February 2015 and March 2017 were included in this study. Three years postoperatively, range of motion (ROM), Knee Society Score (KSS), Knee Injury and Osteoarthritis Outcome Score (KOOS) and Forgotten Joint Score (FJS) were recorded and compared with preoperative scores. Radiographic analyses including mechanical alignment, component alignment, and incidence of radiolucent lines also were undertaken based on the radiographs three years postoperatively.Results: One-hundred twenty-two knees (70%) were available for 3-year follow-up data using KOOS, except for the sports subscale. Postoperative KOOS-symptom, -pain and -ADL were > 85 points, but KOOS-sports, -QOL and FJS were less satisfactory. ROM, KSS and all the subscales of KOOS were significantly improved compared with preoperative scores. Postoperative mean FJS was 66 and was significantly correlated with all the subscales of KOOS, but not with postoperative ROM. Radiolucent lines ≧1 mm wide were detected in five knees (4.1%). There were no major complications needing revision surgeries.Conclusions: Patient-reported outcomes (PROs) for symptoms, pain and ADL after the CR-FINE TKA were generally improved, but those for sports, QOL and FJS were improved less. The incidence of radiolucent lines was rare but detected around the femoral components. Improvements of surgical technique or innovation of the implant design with mid- to long-term follow-up will be necessary to achieve better PROs from patients receiving the FINE knee.

Simulating Airway Collapse in Obstructive Sleep Apnea Using Fluid-Structure Interaction Methodologies

Obstructive Sleep Apnea (OSA) is a prevalent disease among adults and children (Macey, Woo, Kumar, Cross, & Harper, 2010). Patients with OSA have recurrent episodes of airflow limitation during sleep, which lead to daytime sleepiness and several comorbidities, including cardiovascular diseases (Durán, Esnaola, Rubio, & Iztueta, 2001). During the episode of OSA, the airway is partially occluded (hypopnoeas) or totally blocked (apneas). Since the velopharynx is the narrowest segment of the pharyngeal airway, the local air velocity increases significantly leading to the large decrease in the intraluminal pressure. The relationship between the distribution of the minimum pressure and the anatomical geometry of the airway is thus very important. Hence, understanding the mechanical interaction between the soft palate and air flow is important in investigating OSA pathology.

Evaluation of Total Ankle Arthroplasty Design Considered Motion Characteristics of Ankle Joint for Responding to Sudden Tilting Perturbation

Category: Ankle, Ankle Arthritis Introduction/Purpose: Total Ankle Arthroplasty (TAA) has been introduced as one of treatment methods for the arthritis of the ankle joint. Traditional TAAs have been generally designed considering the anatomical geometry and motion characteristics of the ankle joint for responding to general activities of daily living (ADLs). However, traditional TAA designs do not well consider the anatomical geometry and motion characteristics for responding to a sudden perturbation although the ankle joint contributes partially to human balance to prevent falling induced by a sudden perturbation. The aims of the current study were therefore to identify the anatomical geometry and motion characteristics of the ankle joint during sudden tilting perturbations, to reflect the motion characteristics in the design of TAA, and to evaluate the design. Methods: Following Institutional Review Board approval (IRB No SJU-2015-002), seven healthy participants with no sign of musculoskeletal pathology (gender: 7male, 25.5±1.7 years, height: 173.9±6.4 cm, weight: 71.3±6.5 kg) were tested to identify the motion characteristics of the ankle joint during sudden tilting perturbations. Eight sudden tilting perturbations were then implemented by the tilting perturbation simulator developed by our research group. The motion characteristics were measured by using a three-dimensional motion capture system with eight infrared cameras (T-10 s, VICON Motion System Ltd., UK). The motion characteristics, particular in the range of motion (ROM) and motion trajectory, were reflected in the design of TAA. The evaluation of the design of TAA was conducted using finite element (FE) analysis in accordance with the international testing standard ASTM F2665, F1223 and F1814. Results: Dorsi/plantar flexion, inversion/eversion and abduction/adduction were ranged from 11.2±1.5° to -9.3±3.5°, 7.0±4.0° to - 7.8±4.9°, and 0.7±0.2° to -1.0±0.2°, respectively, for the sudden tilting perturbations. Dorsi/plantar flexion of TAA designed newly were 1.5 times larger than that measured from the experiment above, with no interference. Inversion/eversion and internal/external rotation of TAA designed newly were favorably compared to those measured from the experiment above. The motion trajectories were different a little compared to those measured from the experiment above. Maximum von mises stresses predicted from FE analysis with the international test conditions were not exceed a yielding strength of the material used for TAA designed newly and no dislocations among the TAA components were identified. Conclusion: The results indicated that a realization of the natural ankle joint motion trajectory should be improved although TAA design suggested in the current study might well present ROMs for responding to sudden tilting perturbations and have a proper structural stability corresponded to the standard criterion recommended from the international testing standard. The TAA design will be, therefore, modified more considering advanced anatomical and biomechanical parameters, particular in the characteristics of the ankle joint motion trajectory, in our ongoing study. The current study may be, however, valuable to suggesting new TAA design for responding to a sudden perturbation to prevent falling.

Finite element analysis of periventricular lucency in hydrocephalus: extravasation or transependymal CSF absorption?

OBJECT Periventricular lucency (PVL) is often observed in the hydrocephalic brain on CT or MRI. Earlier studies have proposed the extravasation of ventricular CSF into the periventricular white matter or transependymal CSF absorption as possible causes of PVL in hydrocephalus. However, there is insufficient evidence for either theory to be conclusive. METHODS A finite element (FE) model of the hydrocephalic brain with detailed anatomical geometry was constructed to investigate the possible mechanism of PVL in hydrocephalus. The initiation of hydrocephalus was modeled by applying a transmantle pressure gradient (TPG). The model was exposed to varying TPGs to investigate the effects of different geometrical characteristics on the distribution of PVL. The edema map was derived based on the interstitial pore pressure. RESULTS The model simulated the main radiological features of hydrocephalus, i.e., ventriculomegaly and PVL. The degree of PVL, assessed by the pore pressure, was prominent in mild to moderate ventriculomegaly. As the degree of ventriculomegaly exceeded certain values, the pore pressure across the cerebrum became positive, thus inducing the disappearance of PVL. CONCLUSIONS The results are in accordance with common clinical findings of PVL. The degree of ventriculomegaly significantly influences the development of PVL, but two factors were not linearly correlated. The results are indicative of the transependymal CSF absorption as a possible cause of PVL, but the extravasation theory cannot be formally rejected.

Sensitivity of proximal femoral stiffness and areal bone mineral density to changes in bone geometry and density

Areal bone mineral density (aBMD) is the most common surrogate measurement for assessing the bone strength of the proximal femur associated with osteoporosis. Additional factors, however, contribute to the overall strength of the proximal femur, primarily the anatomical geometry. Finite element analysis (FEA) is an effective and widely used computer-based simulation technique for modelling mechanical loading of various engineering structures, providing predictions of displacement and induced stress distribution due to the applied load. FEA is therefore inherently dependent upon both density and anatomical geometry. FEA may be performed on both three-dimensional and two-dimensional models of the proximal femur derived from radiographic images, from which the mechanical stiffness may be predicted. It is examined whether the outcome measures of two-dimensional FEA, two-dimensional, finite element analysis of X-ray images (FEXI), and three-dimensional FEA computed stiffness values of the proximal femur are more sensitive than aBMD to changes in trabecular bone density and femur geometry. It is assumed that if an outcome measure follows known trends with changes in density and geometric parameters, then an increased sensitivity will be indicative of an improved prediction of bone strength. All three outcome measures increased non-linearly with trabecular bone density, increased linearly with cortical shell thickness and neck width, decreased linearly with neck length, and were relatively insensitive to neck-shaft angle. For femoral head radius, aBMD was relatively insensitive, with two-dimensional FEXI and three-dimensional FEA demonstrating a non-linear increase and decrease in sensitivity respectively. For neck anteversion, aBMD decreased non-linearly, whereas both two-dimensional FEXI and three-dimensional FEA demonstrated a parabolic-type relationship, with the maximum stiffness being achieved at an angle of approximately 15°. Multi-parameter analysis showed that all three outcome measures demonstrated their highest sensitivity to a change in cortical thickness. When changes in all input parameters were considered simultaneously, three and two-dimensional FEA had statistically equal sensitivities (0.41 ± 0.20 and 0.42 ± 0.16 respectively, p= ns) that were significantly higher than the sensitivity of aBMD (0.24 ± 0.07; p=0.014 and 0.002 for three-dimensional and two-dimensional FEA respectively). This simulation study suggests that since mechanical integrity and FEA are inherently dependent on anatomical geometry, FEXI stiffness, being derived from conventional two-dimensional radiographic images, may provide an improvement in the prediction of bone strength of the proximal femur than currently provided by aBMD.