Lisfranc injuries in the athlete.

Injuries to the Lisfranc joint in the athlete comprise a very small proportion of tarsometatarsal injuries and are unique in several different ways. The energy involved appears to be on a much smaller order of magnitude than more commonly encountered injuries leading to obvious fracture and dislocation. Second metatarsal subluxation with diastasis between the first and second metatarsal tends to be the most commonly encountered injury; however, the true extent of injury cannot be based solely on the amount of diastasis present. Lateral weight-bearing radiographs facilitate evaluation of the normal medial cuneiform-fifth metatarsal relationship, which when disrupted indicates an injury more significant than a simple sprain and the possible need for open reduction and internal fixation. Finally, the restoration of this normal radiographic relationship between the medial cuneiform and fifth metatarsal on lateral weight-bearing views correlates well with the prognosis for achieving an asymptomatic, well-functioning foot, allowing a return to a competitive level of athletic participation.

Comparison of human and canine external femoral morphologies in the context of total hip replacement.

The canine is frequently used as a model for human hip arthroplasty research. In order to better understand the appropriateness of the canine as a model for human total hip replacement studies, the external morphology of canine and human femurs were examined and compared. Several differences were found between canine and human femora, including angular measurements, anterior bow, and femoral head position relative to the femoral diaphysis. In addition, the human femur was noted to undergo age-related changes in several of the measured parameters. The canine femur did not exhibit any age-related changes in the measured parameters. This study suggests that there are limitations to the use of the canine model in human hip arthroplasty research, and that discretion must be exercised when attempting to extrapolate results from a canine study to the human clinical condition.

Implications of reference axes used for rotational alignment of the femoral component in primary and revision knee arthroplasty.

A careful review of the literature revealed that no data had been reported on the angular difference or similarity between the posterior condylar axis used by many surgeons for primary total knee arthroplasty and the transepicondylar axis, which has been considered a useful anatomical landmark for femoral component placement in revision total knee arthroplasty. The purpose of this study was to determine whether measurable differences exist between the posterior condylar axis and the transepicondylar axis of the human femur. Nineteen pairs of human donor femora were measured. This study demonstrated that when the posterior condylar axis was taken as 0 degrees of rotation, the transepicondylar axis was found to be approximately 5 degrees externally rotated for both right and left femora, a significant difference (P < .05). However, there was no statistically significant difference in the angle measured between the posterior condylar axis and the transepicondylar axis when comparisons were made between matched right and left femora (P > .05). It is suggested that this information can be applied to improving the techniques currently used in the placement of both primary and revision femoral knee components.

Histologic analysis of a retrieved expanded polytetrafluoroethylene posterior cruciate ligament.

An expanded polytetrafluoroethylene (PTFE) prosthesis used to reconstruct the posterior cruciate ligament in a 37-year-old Caucasian male was retrieved and histologically examined in this study. Backscattered electron (BSE) microscopy, utilized to observe the mineralized tissue ingrowth into the retrieved specimen, revealed an absence of bony ingrowth within the graft. Light microscopy demonstrated an exuberant foreign body giant cell response surrounding and invading the substance of the graft, and also revealed evidence of graft degradation. These observations indicate that PTFE may not be as favorable a material for reconstruction of ligamentous tissues as previously reported.