The effect of distal screw orientation on the intrinsic stability of a tibial intramedullary nail.

To compare the intrinsic stability of two distal interlocking screw orientations for tibial nailing of distal third tibial diaphyseal fractures without isthmal support, six Depuy (Warsaw, Indiana) tibial intramedullary nails were implanted in simulated distal tibiae. The constructs received both two parallel (medial to lateral) and two perpendicular (one medial to lateral, one anterior to posterior) distal interlocking screws in a random order Angular, translational, and torsional displacements of the nails were measured in response to 70 N proximal applications of anterior, posterior, medial, and lateral loads, and a 7.7 Newton-meter torsional load. There were no differences in medial or lateral angulations between the screw orientations (average: 2.5 degrees, p > 0.8). Angulation in the sagittal plane (anterior and posterior) was slightly less for parallel screw fixation (1.6 degrees versus 2.4 degrees), but this was not statistically significant (p > 0.1). Rotational angulation was higher in the parallel (average: 9.9 degrees) versus the perpendicular (average: 8.1 degrees) screw orientation, but these results were not statistically significant (p > 0.1). Pure translation did not occur in either the parallel or perpendicular screw orientations. These results indicate that fixation stability of these tibial intramedullary nails is not significantly influenced by distal interlocking screw orientation in response to sagittal, coronal, or rotational forces.

Efficacy of combined technetium-99m sulfur colloid/indium-111 leukocyte scans to detect infected total hip and knee arthroplasties.

The reliability of combined indium-111 leukocyte/technetium-99m sulfur colloid scans, with and without the addition of blood pooling and blood flow studies, in the diagnosis of infected total joint arthroplasty was investigated. Both scans were performed on 58 patients before reoperation of total hip or knee arthroplasty in the period 1996-1999. Results for imaging alone included 100% specificity, 46% sensitivity, 100% positive predictive value, 84% negative predictive value, and 88% accuracy. Inclusion of blood pooling and flow phase data improved results to 66% sensitivity, 89% negative predictive value, and 90% accuracy, with reductions in specificity (98%) and positive predictive value (91%). Routine use of these radionuclide scans is not supported by these data.

Midterm clinical and radiographic results with the genesis I total knee prosthesis.

The midterm results of primary posterior cruciate ligament-retaining, minimally conforming, cemented modular total knee arthroplasties using the Genesis I prosthesis in 110 knees in 72 patients were reviewed. Patients were evaluated at a mean follow-up of 7.3 years by Knee Society pain and functional scores, radiographic and survivorship analysis, and Western Ontario and MacMaster Universities Osteoarthritis Index (WOMAC) health status questionnaire. Range of motion increased from an average of 96.3 degrees to 112.5 degrees. Knee Society pain and functional scores increased from preoperative averages of 55 and 44 to 92 and 88, respectively. There were 91 excellent, 16 good, 1 fair, and 2 poor results. WOMAC scores were increased significantly in each subcategory examined (pain, stiffness, and physical function). Kaplan-Meier survivorship was 97% at 10 years. An increase in loosening as a result of eccentric stress concentration secondary to the nonconforming design of this prosthesis, theoretically a matter of some clinical concern, was not shown in this investigation.