Results may lead to the use of a two-bundle technique.

The anterior cruciate ligament (ACL) can be anatomically divided into anteromedial (AM) and posterolateral (PL) bundles. Current ACL reconstruction techniques focus primarily on reproducing the AM bundle, but are insufficient in response to rotatory loads. The objective of this study was to determine the distribution of in situ force between the two bundles when the knee is subjected to anterior tibial and rotatory loads. Ten cadaveric knees (50 k 10 years) were tested using a roboticluniversal forcemoment sensor (UFS) testing system. Two external loading conditions were applied: a 134 N anterior tibial load at full knee extension and 15", 30°, 60", and 90" of flexion and a combined rotatory load of 10 N m valgus and 5 N m internal tibial torque at 15" and 30" of flexion. The resulting 6 degrees of freedom kinematics of the knee and the in situ forces in the ACL and its two bundles were determined. Under an anterior tibial load, the in situ force in the PL bundle was the highest at full extension (67 k 30 N) and decreased with increasing flexion. The in situ force in the AM bundle was lower than in the PL bundle at full extension, but increased with increasing flexion, reaching a maximum (90 f 17 N) at 60" of flexion and then decreasing at 90". Under a combined rotatory load, the in situ force of the PL bundle was higher at 15" (21 k 11 N) and lower at 30" of flexion (14 f 6 N). The in situ force in the AM bundle was similar at 15" and 30" of knee flexion (30k 15 vs. 3 5 2 16 N, respectively). Comparing these two external loading conditions demonstrated the importance of the PL bundle, especially when the knee is near full extension. These findings provide a better understanding of the function of the two bundles of the ACL and could serve as a basis for future considerations of surgical reconstruction in the replacement of the ACL.

Constituting approximately 10% of flowering plant species, orchids (Orchidaceae) display unique flower morphologies, possess an extraordinary diversity in lifestyle, and have successfully colonized almost every habitat on Earth 1-3 . Here we report the draft genome sequence of Apostasia shenzhenica 4 , a representative of one of two genera that form a sister lineage to the rest of the Orchidaceae, providing a reference for inferring the genome content and structure of the most recent common ancestor of all extant orchids and improving our understanding of their origins and evolution. In addition, we present transcriptome data for representatives of Vanilloideae, Cypripedioideae and Orchidoideae, and novel thirdgeneration genome data for two species of Epidendroideae, covering all five orchid subfamilies. A. shenzhenica shows clear evidence of a whole-genome duplication, which is shared by all orchids and occurred shortly before their divergence. Comparisons between A. shenzhenica and other orchids and angiosperms also permitted the reconstruction of an ancestral orchid gene toolkit. We identify new gene families, gene family expansions and contractions, and changes within MADS-box gene classes, which control a diverse suite of developmental processes, during orchid evolution. This study sheds new light on the genetic mechanisms underpinning key orchid innovations, including the development of the labellum and gynostemium, pollinia, and seeds without endosperm, as well as the evolution of epiphytism; reveals relationships between the Orchidaceae subfamilies; and helps clarify the evolutionary history of orchids within the angiosperms.

Double-bundle anterior cruciate ligament (ACL) reconstruction reproduces anteromedial and posterolateral bundles, and thus has theoretical advantages over conventional single-bundle reconstruction in controlling rotational torque in vitro. However, its superiority in clinical practice has not been proven. We analyzed rotational stability with three reconstruction techniques in 60 consecutive patients who were randomly divided into three groups (double-bundle, anteromedial single-bundle, posterolateral single-bundle). In the reconstructive procedure, the hamstring tendon was harvested and used as a free tendon graft. Followup examinations were performed 1 year after surgery. Anteroposterior laxity of the knee was examined with a KT-1000 arthrometer, whereas rotatory instability, as elicited by the pivot shift test, was assessed using a new measurement system incorporating three-dimensional electromagnetic sensors. Routine clinical evaluations, including KT examination, demonstrated no differences among the three groups. However, using the new measurement system, patients with double-bundle ACL reconstruction showed better pivot shift control of complex instability than patients with anteromedial and posterolateral single-bundle reconstruction.

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