A study of the social service rendered to seventy-one patients released on indefinite visit from the Metropolitan State Hospital between January 1, 1944 and July 1, 1944

Thesis (M.S.)--Boston University, 1948. This item was digitized by the Internet Archive

Patellofemoral joint compression forces in backward and forward running

AbstractPatellofemoral pain (PFP) is a common injury and increased patellofemoral joint compression forces (PFJCF) may aggravate symptoms. Backward running (BR) has been suggested for exercise with reduced PFJCF.The aims of this study were to (1) investigate if BR had reduced peak PFJCF compared to forward running (FR) at the same speed, and (2) if PFJCF was reduced in BR, to investigate which biomechanical parameters explained this. It was hypothesized that (1) PFJCF would be lower in BR, and (2) that this would coincide with a reduced peak knee moment caused by altered ground reaction forces (GRFs).Twenty healthy subjects ran in forward and backward directions at consistent speed. Kinematic and ground reaction force data were collected; inverse dynamic and PFJCF analyses were performed.PFJCF were higher in FR than BR (4.5±1.5; 3.4±1.4BW; p<0.01). The majority of this difference (93.1%) was predicted by increased knee moments in FR compared to BR (157±54; 124±51Nm; p<0.01). 54.8% of differences in knee moments could be predicted by the magnitude of the GRF (2.3±0.3; 2.4±0.2BW), knee flexion angle (44±6; 41±7) and center of pressure location on the foot (25±11; 12±6%) at time of peak knee moment. Results were not consistent in all subjects.It was concluded that BR had reduced PFJCF compared to FR. This was caused by an increased knee moment, due to differences in magnitude and location of the GRF vector relative to the knee. BR can therefore be used to exercise with decreased PFJCF

Rahasia sukses skenario film-film Box Office. : 5 langkah jitu mengadaptasi apa pun menjadi skenario jempolan.

Bandungxxx; 307 p.; 24 cm

Specimen-specific, three-dimensional knee joint mechanics: normal and reconstructed

Three-dimensional data was obtained from three cadaver specimens for both the normal, intact knee and specimens with a posterior cruciate ligament (PCL) retaining total knee replacement (TKR). The moment arm of the patellar tendon and the relative displacements of the tibia and patella were measured during leg-extension. The data obtained for the total knee replacement was compared to the normal, intact knee. Specimen-specific, three-dimensional mathematical models of the cadaver specimens were created for both the normal, intact knee and those with a total knee replacement to evaluate ligament and joint function for leg extension. The ligament origins and insertions and articular geometry were obtained from MRI and CT data obtained for each specific cadaver. Twelve elastic elements described the geometry and mechanical properties of the cruciate and collateral ligaments and the posterior capsule of each knee. The values of the ligament reference lengths and stiffness’ were adjusted to match in vitro anterior-posterior and rotational laxity data for the specimen-specific knees. Interpenetration of the femur and tibia was taken into account by modeling cartilage as a linearly-elastic homogeneous material mounted on rigid bone. The contacting surfaces of the patella and femur were assumed to be rigid. The models were used to simulate active knee extension, where a known force was applied to the quadriceps tendon. Quantitative comparisons of each model with the experimental data indicate that specimen-specific models reproduce the relative movements of the tibia and patella more accurately than average knee models due to the care taken in accurately representing the bone geometry and mechanical properties of the ligaments. The model calculations of the patellofemoral joint-reaction force suggest that PCL-retaining TKR’s are capable of reproducing the normal state of patellofemoral mechanics during knee extension. The calculations for the TKR models show that the articular geometry of the TKR components contributes to an increase in PCL force as compared with the intact models.Mechanical Engineerin

Factors affecting the cement penetration of a hip resurfacing implant: An in vitro study

An understanding of how the cementing technique influences cement penetration is important for surgeons to plan and conduct hip resurfacing procedures. Therefore the aim of this study is to determine the influence of the following parameters on cement penetration: use of pulse lavage, type of cement, and the standing period of the cement. Nine fresh frozen paired whole cadaver femora were used to investigate cement penetration. The femora were divided into three paired groups: (A) compared the use of pulse lavage to no pulse lavage, (B) compared two low viscosity bone cements SULCEM-3 (Zimmer GmbH, Switzerland) and Surgical Simplex (Stryker Orthopaedics, USA), and (C) compared bone cement viscosities using standing times of 1.5 min. and 3 min. The Durom Hip Resurfacing implant (Zimmer GmbH, Switzerland) was used in all groups. A single slice was taken out of the center of each head. Cement penetration ratio (penetration area divided by the bone area enclosed by implant) and mean cement penetration depth were measured. Cement penetration is increased using pulse lavage, and has the tendency to increase with increasing the cement standing time from 1.5 to 3 min. No difference in cement penetration was found when different cement brands of comparable viscosity were used