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At least 1,405 records · Page 78Linked to original sources
PubMed2005

Reconstruction of the anterior cruciate ligament with a patella-tendon-bone graft may lead to a permanent loss of bone mineral content due to decreased patellar tendon stiffness.

Immobilisation induces bone loss. Evidence from studies in animals and healthy humans that were immobilised for a limited time indicates that, in general, bone mass may be restored even in adults. Following conservative management of partial tears of the anterior cruciate ligament (ACL), bone loss is often negligible (2-3%). After surgical reconstruction, however, there is greater bone loss (15-20%), with little or no recovery. Bones adapt to the stresses they experience. Also, the largest forces in the musculoskeletal system arise from muscle pull. Tendons transmit these forces. Many surgical techniques for ACL reconstruction use autologous tendon grafts. We hypothesise that tissue harvesting causes weakening of the formerly intact tendon, which, in turn, leads to reduced muscle pull and subsequent bone loss in those parts of the bone that are loaded by the tendon. If our hypothesis holds true, it may change patients' and surgeons' choice of management. Clinical follow-up should assess the functional result with greater scrutiny, possibly including the assessment of bone mineral content. This may be particularly important since there is accumulating evidence that a decrease in bone mineral density (BMD) preceedes, and hence may be a cause of, osteoarthritis.

Animals↗
PubMed2002

Rate of blunt impact loading affects changes in retropatellar cartilage and underlying bone in the rabbit patella.

Our laboratory has developed a small animal model using Giant Flemish rabbits to examine chronic degradative changes in joint tissues following a blunt impact. Historically, we observe surface fissuring and decreases in the elastic modulus of retropatellar cartilage along with thickening of the underlying subchondral bone. Previous studies resulted in load insults that peaked in approximately 5ms, while loads that occur during automotive accidents or heavy exercise can produce longer rise times. The objective of the current study was to examine the influence of blunt impact loading rate using our established model. We hypothesized that the extent of fissuring and softening of retropatellar cartilage following impact would not be significantly different for a high (5ms to peak) versus low (50ms to peak) rate of loading experiment. Eight animals were impacted with a high rate of loading blunt impact, while ten animals were subjected to the same impact load at a low rate of loading. An additional eight animals served as a control population. All animals were sacrificed 12 months post-impact. The study yielded unexpected results for the first hypothesis. The high rate of loading experiments generated more surface fissuring of the retropatellar cartilage than the low rate of loading experiments. However, the degree of softening was similar for the two rates, which supported the second hypothesis. Furthermore, the study documented more thickening of bone underlying retropatellar cartilage following the high versus the low rate of loading experiments. The current study suggested that chronic injury mechanisms may be highly dependent on the rate of impact loading. These data could become extremely relevant in the development of high-velocity "safety" devices, such as knee air bags, that are needed to help position an unbelted occupant in an automobile crash.

Animals↗
PubMed1999

Fractures of the patella after total knee replacement.

Pateller fractures in association with total knee replacement are uncommon, but potentially a cause of an unsatisfactory clinical outcome. Patient, implant, and technical factors are important predisposing causes of these patellar fractures. Prevention is the best treatment. Important outcome criteria include the integrity of the extensor mechanism, patellar implant fixation, and anatomic location. Patients requiring operative intervention often have an unsatisfactory outcome.

Arthroplasty, Replacement, Knee↗