Osteochondritis dissecans (OCD) is a condition affecting the subchondral bone of joints with secondary effects on articular cartilage that results in pain, effusions, loose-body formation, and mechanical symptoms. Left untreated, OCD can lead to the development of degenerative arthritis secondary to joint incongruity and abnormal wear patterns. This article discusses the etiology of knee OCD lesions, clinical presentation, proper evaluation, and treatment options. Treatment of OCD may include nonoperative measures or operative procedures ranging from drilling or fixation of fragments to complex reconstruction procedures such as autologous chondrocyte implantation, osteochondral autograft, and fresh osteochondral allograft. Physicians must consider many factors, including the patient's age and skeletal maturity, as well as size, location, and stability of OCD lesions to determine the proper course of treatment. [J Knee Surg. 2008;21:106-115.]
Posterior wall blowout is an important potential source of anterior cruciate ligament reconstruction failures that can be avoided if surgeons adhere to proper technique and are vigilant in confirming appropriate femoral tunnel placement. This article reviews techniques for avoidance, recognition, and salvage of posterior wall blowouts in anterior cruciate ligament reconstruction surgery. [J Knee Surg. 2008;21:235-240.]
The treatment of symptomatic articular cartilage defects of the knee has evolved tremendously in the past decade. Previously, there were limited treatment options available to patients who suffered from either partial-thickness or full-thickness cartilage lesions. Because articular cartilage has a limited capacity for healing, patients were often treated symptomatically until they became candidates for osteotomy or total joint replacement. Recently, both reparative and restorative procedures have been developed to address this significant source of morbidity in young active patients. Microfracture is a reparative technique that induces a healing response to occur in an area of articular cartilage damage. Osteochondral autografts and allografts in addition to autologous chondrocyte implantation are restorative techniques aimed at recreating a more normal articular surface. Both types of procedures have been developed to alleviate the symptoms associated with focal chondral defects, as well as limit their potential to progress to a diffuse degenerative arthritis. Treatment can vary depending on both cartilage defect and patient factors. This article summarizes the various treatment options that have recently become available.
To assess factors that limit human muscle strength and growth, we examined the relationship between performance and body dimensions in the world weightlifting champions of 1993-1997. Weight lifted varied almost exactly with height squared (Ht(2.16)), suggesting that muscle mass scaled almost exactly with height cubed (Ht(3.16)) and that muscle cross-sectional area was closely correlated with body height, possibly because height and the numbers of muscle fibers in cross section are determined by a common factor during maturation. Further height limitations of muscle strength were shown by only one male champion >/=183 cm and no female champions >/=175 cm. The ratio of weight lifted to mean body cross-sectional area was approximately constant for body-weight classes =83 kg for men and =64 kg for women and decreased abruptly for higher weight classes. These findings suggest a nearly constant fraction of body mass devoted to muscle in lighter lifters and a lesser fraction in heavier lifters. Analysis also suggests that contractile tissue comprises approximately 30% less body mass in female champions.
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