The study determined if the hip hop culture influenced the collegiate experience, specifically attitude, socialization, and personal goals. Qualitative research methodology resulted in the use of semi-structured interviews. Participants were traditional undergraduate students who self-identified as listening to hip hop music at Ball State University. Data were collected in January and February of 2006.The hip hop culture influenced the socialization of the student participants. Participant attitude was seldom influenced by the hip hop culture. Mainstream hip hop had minimal influence on the personal goals of students. The hip hop culture was more than music to the undergraduate students; it was a way of life and provided the motivation to pursue an education. / Department of Educational Leadership

The experiments presented in this thesis provide novel insight into two scarcely studied areas in the field of lateral hip impact biomechanics. The high energy nature of hip impacts requires high sampling rates for accurate study of hip impact dynamics. However, to date only optical motion capture, with relatively lower sampling rates (240-400 Hz), has been used to measure pelvic deflection during hip impact experiments with human participants. As such, the results from the first study compared the differences between two measurement systems (3D optical motion tracking and 2D high speed videography) in measuring common variables of impact biomechanics (peak force, time to peak force, peak deflection, time to peak deflection and energy absorbed). Although significant differences were seen between systems in measuring TFmax and Emax, the magnitude of differences were at or below 5% of the total magnitude of each measured variable. Furthermore, averaging impacts within a subject reduced the differences between systems for Emax. Furthermore, this study showed the effect of sampling rate on measuring hip impact dynamics, and how sampling at lower frequencies affects the aforementioned variables. Tests on the effect of sampling rate found differential effects contingent on the dependent variable measured. Sampling as low at 300 Hz, significantly reduced measures of Fmax and Dmax, but only by on average 0.7 and 0.5 %, respectively. Whereas measures of TFmax and TDmax increased by on average 9.5 and 6.8 %. Sampling Emax at 500 Hz and 300 Hz increased measures of impact absorption by 2.2 and 2.8 % respectively. Sampling at 4500 Hz was the lowest sampling rate that was not significantly different from 9000 Hz across all dependent variables. The second study in this thesis investigates the influence of contact area on load distribution during lateral hip impacts. In summary, this study shows that all three time-varying signals (Ft, FTt and Dt ) were significantly correlated with time-varying contact area (Ct). These results lend support to the possibility of modeling lateral hip impacts with contact models, but provide little support for a Hertzian model adaptation. Analysis on the relationships between body mass and BMI found both anthropometric measures to correlate significantly with peak impact force, but not with peak impact force directed to the greater trochanter. These results bring into question the feasibility of modeling hip fracture risk with body mass or BMI as inputs, without further investigating the distribution of impact force to the greater trochanter. In this study only contact area was significantly correlated with all measures of GT specific loading, and has never before been implemented in predictive modelling of hip fracture risk. Finally, this study found that although effective mass, total body mass and BMI were significantly correlated with the contact area at peak force, they only accounted for 21, 22 and 33% of the variance in CA. Altogether, this study sheds new light on the role that contact area plays in lateral hip impact loading and the importance of understanding load distribution during lateral hip impacts. It also highlights the importance of moving towards predictive models that incorporate more robust estimate of body composition and geometry, with hopes that these will better help estimate the risk of hip fracture. Overall, this thesis provides insight into the expected differences between measuring hip impact dynamics with two, relatively different measurement techniques. In addition, it highlights the need for further study on the relationship between contact geometry and hip fracture risk, something not currently implemented in most hip fracture risk models.

Hip resurfacing arthroplasty is touted as an attractive alternative to total hip arthroplasty for treatment of severe joint pain and limited mobility in young patients because it is bone conserving and allows for a greater range of motion. There is concern in the orthopaedic community, however, regarding surgically-induced deformation of hip resurfacing cups. Cup deformation could potentially compromise the tight clearance between the femoral head and cup, resulting in increased wear, acoustic emissions, and joint binding. This phenomenon has been investigated both experimentally and with finite element analysis (FEA). Finite element studies have contributed significantly to our understanding of cup deformation, such as the effect of different cup dimensions on deformation results, but unfortunately such studies were deficient in a number of ways. The first objective of this thesis was to create a three-dimensional finite element model of resurfacing cup deformation that addressed the limitations of previous models pertaining to pelvic geometry, meshing, material properties, and cup insertion, in order to more fully elucidate cup deformation. The second objective was to demonstrate that two-dimensional characterization of cup deformation at the cup rim is insufficient, by more fully characterizing cup deformation in three-dimensions. The geometry was obtained via laser scanning and digital processing of a hemi-pelvis replica, meshing was performed without the use of shell elements, linear elasticity with strain-hardening after the onset of yielding was assigned to the cup and bone, and the most appropriate method for simulation of cup insertion was determined via two-dimensional axisymmetric analyses. Also, cup deformation was characterized in three-dimensions. The key findings of this thesis are that bone yield behaviour has important implications on press-fitting simulation, and the cup deforms irregularly and possibly plastically during press-fitting. A three-dimensional finite element model of resurfacing cup deformation that addressed the limitations of previous models was successfully created. Measurement of deformation at the rim of the resurfacing cup for characterization of cup deformation is insufficient; full characterization of cup deformation in three-dimensions is necessary. Future work should incorporate clinical testing to obtain model inputs such as impact and muscle forces, as well as model validation.

As implant survival extends into the second and third decades focal osteolysis around cemented femoral components in total hip replacement is emerging as an important failure mechanism. Whilst the problem of focal osteolysis is well recognised, there are many aspects of its development which are poorly understood. The broad aim of this thesis is to try to provide some insights into how, why and where focal osteolysis develops around the cemented femoral component. There are broadly two sections to this thesis, chapters 2-5 present clinical and geometrical studies and chapters 6-10 a series of experimental studies. The aim of the first section was to establish what is observed in clinical practice, the aim of the second to try to explain these findings. A mid-term clinical study showed that focal osteolysis is more common with rough than polished stems that differed in no aspect other than their surface finish. Further studies established that focal osteolysis is probably always associated with defects in the cement mantle. These defects occur anteriorly at the mid-stem of the prosthesis and posteriorly at the component tip. The distribution of focal osteolysis and its strong association with cement mantle defects suggests the importance of the stemcement interface as a pathway for fluid and debris to reach the distal femur. However, at 15-25 years, osteolysis rarely develops with the polished Exeter stem even in the presence of confirmed defects in the cement mantle, suggesting that the stem seals the stem-cement interface against fluid and debris. In an attempt to explain the clinical findings a series of bench top experiments were undertaken. These studies showed that the behaviour of fluid and dye at the stemcement interface was significantly influenced by component surface finish. Bonded and debonded stem-cement interfaces of rough stems provided an incomplete barrier to fluid movement along this interface. In contrast, polished stems both bonded and debonded were able to provide a seal at the stem-cement interface. The seal at this interface was improved with component subsidence in the presence of rotational stability. It is believed that this thesis provides a rationale explanation for why focal osteolysis rarely develops around the Exeter stem in clinical practice. It also explains how, where, and why osteolysis develops around certain designs of cemented femoral components used in total hip replacement.

The tribological performance of internal joint prostheses is a fundamental influence on their longevity. The aim of this study is to characterise the tribological performance of the Porous Coated Anatomic total hip replacement by the analysis of 119 explanted prostheses. Investigations of the friction, wear, surface topography and wear debris were made and related to the joint's clinical performance. The friction of the joints at explant was similar to that of new prostheses. The median total wear volume (419mm(^3)) was found to agree with previous wear studies suggesting the existence of a threshold wear volume which promotes osteolysis. Clinical wear factor for the whole cohort matched that of alternative joint designs. The femoral head finish was shown to degrade but not in proportion to implant duration. The roughness of the UHMWPE liner was shown to fall but no relationship with any head roughness, or temporal, parameter could be distinguished. Simulator studies confirmed that the wear factor of a joint is likely to change over its lifespan. Wear models published previously describing the influence of femoral head roughness on wear could not predict the performance of explanted prostheses. An alternative relationship was observed indicating that head roughness is not as powerful a predictor of wear as previously held. A novel technique for the characterisation of the size distribution of ex vivo and in vitro wear debris was developed. A Low-Angle Laser Light Scattering Particle Analyser was used to size particles continuously over a range from 0.5 to 1000μm. This technique offers considerable unprovement over existing microscope-based methods in terms of the detail of the information and does so with less experimental effort. It was shown to be highly accurate and repeatable in preliminary investigations. Case studies of five tissue samples revealed the potential of this method.

No description available.

The tribology of a wide range of designs of compliant layer acetabular cups has been evaluated using a simulator. The simulator applied a dynamic load of 2 kN and a sinusoidal motion of ±25 , and measured the frictional resistance directly. In general the friction developed in these joints was extremely low, with friction factors typically below 0.01. When the experimental results were compared with theoretical estimates of friction a poor correlation was found. Further analysis suggested that the design of compliant layer acetabular cups was insensitive to many of the parameters suggested by theory. In particular, the radial clearance and femoral head size were not found to be critical. In addition, methods were proposed and their effectiveness demonstrated to measure friction at the on-set of motion (start-up friction), and the steady state friction in realistic compliant layer knees. The adhesion between compliant layers and a rigid backing have been investigated, with the aim of developing a good bond between them. The peel test was used to demonstrate an excellent diffusion bond between a low modulus medical grade polyurethane, and a similar high modulus grade of polyurethane. The processing conditions used to manufacture the test piece were optimised to maximise the bond strength. The bond was found to be stable after immersion in Ringers solution at 37 C for 52 weeks, and after acetabular cups were subjected to 14 million 4 kN loading cycles. A six station knee wear simulator was designed and commissioned. The simulator applied a dynamic load and an anterior-posterior translation individually to each station, as well as a flexion-extension motion common to all six stations. The simulator was computer controlled entirely using servo hydraulics. Wear rates were obtained from tests lasting up to 8 million cycles conducted on UHMWPE joints.

Osteoporosis is a major public health problem resulting in substantial hip fracture related morbidity. Using healthcare utilization data, we determined the 1- and 2-year direct attributable healthcare costs associated with hip fractures among Ontario seniors in comparison to a matched non-hip fracture cohort. Over a four-year period (2004-2008) we identified 22,418 females and 7,611 males with an incident hip fracture. Approximately 22% of females and 30% of males died in the first year after fracture. The mean attributable cost in the first year was $36,929 ($52,232 vs. $15,503) among females and $39,479 ($54,289 vs. $14,810) among males. Primary cost drivers included acute hospitalizations, complex continuing care, and rehabilitation. Attributable costs remained elevated into the second year, particularly among those who survived the first year ($9,017 females and $10,347 males). Results from this study will aid policy decision makers in allocating healthcare resources and help feed into future health economic analyses.

Osteoporosis is a major public health problem resulting in substantial hip fracture related morbidity. Using healthcare utilization data, we determined the 1- and 2-year direct attributable healthcare costs associated with hip fractures among Ontario seniors in comparison to a matched non-hip fracture cohort. Over a four-year period (2004-2008) we identified 22,418 females and 7,611 males with an incident hip fracture. Approximately 22% of females and 30% of males died in the first year after fracture. The mean attributable cost in the first year was $36,929 ($52,232 vs. $15,503) among females and $39,479 ($54,289 vs. $14,810) among males. Primary cost drivers included acute hospitalizations, complex continuing care, and rehabilitation. Attributable costs remained elevated into the second year, particularly among those who survived the first year ($9,017 females and $10,347 males). Results from this study will aid policy decision makers in allocating healthcare resources and help feed into future health economic analyses.

Cement - within - Cement (C-C) revision techniques have been demonstrated to reduce the complications associated with removal of secure cement from the femoral canal during revision hip joint arthroplasty. Material failure at the interface between new and old cement mantles represents a theoretical limitation of this technique. The objectives of this thesis are to describe the variability in material properties of uniform and bilaminar polymethylmethacrylate (PMMA) cement mantles in shear with respect to duration of post-cure and the influence of commercial inclusion of antibiotics on bilaminar cement mantle interfacial shear strength. Uniform mantles of Surgical Simplex P and Antibiotic Simplex PMMA cements demonstrated variability in ultimate shear stress to failure with respect to duration of post-cure (p < 0.001), however the variations were quantitatively small and unlikely to be of clinical relevance. Bilaminar cement mantles were 15 - 20 percent weaker than uniform mantles (p < 0.001) and demonstrated similar time dependant material property variations in shear (p < 0.001). Bilaminar PMMA test specimens manufactured using Antibiotic Simplex cement demonstrated equivalent ultimate shear stress to failure as bilaminar specimens manufactured from Surgical Simplex (p=0.52). High C-C interfacial strengths are demonstrated as early as one hour after cement application. Interfacial adhesion by mechanisms other than mechanical interlock significantly influence the bond formed between layered PMMA cements, with an important contribution by diffusion based molecular interdigitation. In the presence of a secure cement-bone interface, C-C femoral revision can be recommended as a viable technique on the basis of the strong interfacial bond formed between new and old cement mantles. The use of Antibiotic Simplex in C-C revision is recommended as detrimental effects on the interfacial shear properties have not been demonstrated with the commercial addition of Tobramycin.