Biomechanical comparison of single- and double-pin fixation for acute slipped capital femoral epiphysis.

Biomechanics of pin fixation for acute slipped capital femoral epiphysis (SCFE) was studied in an in vitro immature canine model. Acute SCFE were created in 24 paired femurs. The paired specimens were pinned with either one or two pins and loaded to failure. Strength and stiffness of the paired limbs were expressed as percentages of the loads necessary to create the initial SCFE in the intact specimen. Strength and stiffness were equivalent statistically for the intact physis and the fractured physis fixed with two pins. Single pinning was only 83% as strong and 78% as stiff as the intact physeal plate. Double-pin fixation is recommended over single-pin fixation for acute SCFE. These data, however, should not be extrapolated to the clinical situation of fixation for chronic SCFE.

Use of a knee-brace for control of tibial translation and rotation. A comparison, in cadavera, of available models.

We assessed the relative restraints that are provided by fourteen currently available functional knee-braces, using six limbs in cadavera. The tests were made at 30 and 60 degrees of flexion of the knee, and a mechanical loading system applied loads that caused anterior-posterior translation and internal-external rotation. The braces limited abnormal tibiofemoral displacements by 10 to 75 per cent in translation; there was more variation in rotation. This study demonstrated that functional knee-braces provide a restraining influence that may be beneficial in the control of abnormal displacements of the knee, but that the degree of restraint varies considerably.