Osteoarthritis is a disease that progresses over time and culminates in the destruction of articular cartilage and joints. Thus, with an increasing elderly population the treatment of knee osteoarthritis has become a major healthcare issue. It has been shown that women are more severely impacted by knee osteoarthritis. Differences in knee anatomy, kinematics, previous knee injury, and hormonal influences may play a role. Sex difference with respect to osteoarthritis presentation, treatment, and the allocation of resources also exists. In general, women present for treatment in more advanced stages of osteoarthritis and have more debilitating pain than their male counterparts. In addition, healthcare providers are more likely to recommend total joint arthroplasty for their male patients. Understanding how and why these gender differences occur is instrumental in formulating an inclusive strategy for combating osteoarthritis in the future.

Segond fractures, or avulsion fractures of the proximal lateral tibial plateau, have been well documented and studied since their original description in 1878. Segond fractures have a widely recognized pathognomonic association with anterior cruciate ligament (ACL) injuries and often prompt orthopedic surgeons to consider reconstruction following radiographic and clinical evaluation. Adolescent patients are particularly vulnerable to these fractures due to the relative weakness of their physeal growth plates compared with the strength of their accompanying ligamentous structures. This article describes a case of a 13-year-old boy who sustained a Segond fracture that was not coupled with an ACL avulsion or tear. The patient sustained a twisting injury to his knee. He presented to the emergency room with an effusion and radiographic findings consistent with a Segond fracture. On follow-up examination 1 week after injury, the ACL was intact. The patient was followed for 5 months of conservative treatment. At final follow-up, the patient had reestablished his previous level of activity. This article describes the history, physical examination, and radiographic findings necessary to care for patients who present with a Segond fracture. Although considered pathognomonic for an associated ACL injury, this article describes a Segond fracture that occurred in isolation.

Abstract. Several recent near-miss encounters with asteroids and comets have focused attention on the threat of a catastrophic impact with the Earth. This document reviews the historical impact record and current understanding of the number and location of Near Earth Objects (NEO's) to address their impact probability. Various ongoing projects intended to survey and catalog the NE0 population are also reviewed.Details are then given of an MSFC-led study, intended to develop and assess various candidate systems for protection of the Earth against NEOs. An existing program, used to model the NE0 threat, was extensively modified and is presented here. Details of various analytical tools, developed to evaluate the performance of proposed technologies for protection against the NE0 threat, are also presented. Trajectory tools, developed to model the outbound path a vehicle would take to intercept or rendezvous with a target asteroid or comet, are described. Also, details are given of a tool that was created to model both the un-deflected inbound path of an NE0 as well as the modified, post-deflection, path.The number of possible options available for protection against the NE0 threat was too numerous for them to all be addressed within the study; instead, a representative selection were modeled and evaluated. The major output from this work was a novel process by which the relative effectiveness of different threat mitigation concepts can be evaluated during future, more detailed, studies. In addition, several new or modified mathematical models were developed to analyze various proposed protection systems. A summary of the major lessons learned during this study is presented, as are recommendations for future work.It is hoped that this study will serve to raise the level attention about this very real threat and also demonstrate that successful defense is both possible and practicable, provided appropriate steps are taken.

Abstract. This paper describes the engineering of several vehicles designed for a crewed mission to the Jovian satellite Callisto. Each subsystem is discussed in detail. Mission and trajectory analysis for each mission concept is described. Crew support components are also described. Vehicles were developed using both fission powered magneto plasma dynamic (MPD) thrusters and magnetized target fusion (MTF) propulsion systems. Conclusions were drawn regarding the usefulness of these propulsion systems for crewed exploration of the outer solar system.

Abstract. Engineering details are presented for a magnetized target fusion (MTF) propulsion system designed to support crewed missions to the outer solar system. Basic operation of an MTF propulsion system is introduced. Structural, thermal, radiation-management and electrical design details are presented. The propellant storage and supply system design is also presented. A propulsion system mass estimate and associated performance figures are given. The advantages of helium-3 as a fusion fuel for an advanced MTF system are discussed.