Double-bundle versus single-bundle ACL reconstruction.

Surgical repair of the anterior cruciate ligament is a fairly common necessity in knee injuries, usually with good to excellent outcomes. However a successful repair and return to activities for a subpopulation of patients, 10% to 30%, remain elusive. Additionally, some athletes have arthritic changes, even with ligament repair. These issues are likely multi-factorial in nature but the debate continues even over which primary operative technique will produce the most favorable outcome. This review examines and discusses the anatomic and historical rationale of double-bundle ACL reconstruction techniques, the published kinematics of double-bundle reconstructions, and the clinical literature comparing double-bundle outcomes to those of the more traditional single-bundle constructs. Conclusions regarding surgical care include a need for more standardization of measuring parameters and the future application of advanced technologies that would inform more correct models of knee kinematics for comparison to various ACL construction approaches, potentially allowing improvement in the techniques of ACL reconstruction.

BioGPS: an extensible and customizable portal for querying and organizing gene annotation resources.

Online gene annotation resources are indispensable for analysis of genomics data. However, the landscape of these online resources is highly fragmented, and scientists often visit dozens of these sites for each gene in a candidate gene list. Here, we introduce BioGPS http://biogps.gnf.org, a centralized gene portal for aggregating distributed gene annotation resources. Moreover, BioGPS embraces the principle of community intelligence, enabling any user to easily and directly contribute to the BioGPS platform.

Total knees designed for normal kinematics evaluated in an up-and-down crouching machine.

We constructed a crouching machine to study the motion of the knee joint, in which a motor was used to wind the quadriceps tendon so as to move the knee from high flexion to extension and back into flexion, while springs simulated hamstrings forces. Seven human cadaveric knees were tested intact and then after anterior cruciate ligament (ACL) resection. Motions of the femur, tibia, and patella were recorded by an optical tracking system. We then inserted plastic models representing commonly used total condylar and posterior stabilized knee replacement designs. Femoral motion was described by successive positions of the transverse axis of the femur projected onto the tibial surface. In the knee replacements, motions were similar to that of an ACL-deficient knee. We then tested two new designs with features intended to prevent anterior paradoxical sliding and to promote a medial pivot motion with femoral rollback primarily on the lateral side. The motion path more closely followed that of the normal intact knee. We concluded that motion guiding features in a total knee replacement could reproduce a normal neutral path that might result in functional improvements for the patient.

Design features of total knees for achieving normal knee motion characteristics.

The goal of the study was to achieve a normal neutral anatomical path of motion with a total knee arthroplasty (TKA) using specific motion-guiding design features. Two reference TKA models were used, consisting of a partially conforming double-dished geometry and the same with a central cam-post for femoral rollback. Four experimental TKA models included features to produce femoral rollback with and without guidance for tibial rotation, and a feature to prevent paradoxical anterior femoral sliding. The femur was loaded down the tibial axis, and the femoral-tibial positions were recorded at a sequence of flexion angles. Subsequently, the positions were recorded with an anterior shear force superimposed. Software was used to reconstruct the paths of the transverse femoral axis on the tibia, during a full flexion range. The reference knees did not reproduce a normal neutral path of motion. However, this was achieved with an experimental design incorporating all of the motion-guiding features.