The "N+10 Rule" to Avoid Graft-Tunnel Mismatch in Bone-Patellar Tendon-Bone ACL Reconstruction Using Independent Femoral Tunnel Drilling.

Background: Graft-tunnel mismatch (GTM) is a common problem in anterior cruciate ligament (ACL) reconstruction (ACLR) using bone-patellar tendon-bone (BPTB) grafts. Hypothesis: Application of the "N+10 rule" in endoscopic ACLR with BPTB grafts will result in acceptable tibial tunnel length (TTL), minimizing GTM. Study Design: Controlled laboratory study. Methods: Endoscopic BPTB ACLR was conducted on the paired knees of 10 cadaveric specimens using 2 independent femoral tunnel drilling techniques-accessory anteromedial portal and flexible reamer. The graft bone blocks were trimmed to 10 × 20 mm, and the intertendinous distance (represented by "N") between the bone blocks was measured. The N+10 rule was used to set the angle of the ACL tibial tunnel guide to the appropriate number of degrees for drilling. The amount of excursion or recession of the tibial bone plug in relation to the anterior tibial cortical aperture was measured in both flexion and extension. A GTM threshold of ±7.5 mm was set based on prior studies. Results: The mean BPTB ACL intertendinous distance was 47.5 ± 5.5 mm. The mean measured intra-articular distance was 27.2 ± 3 mm. Using the N+10 rule, the mean total (flexion plus extension) GTM was 4.3 ± 3.2 mm (GTM in flexion, 4.9 ± 3.6 mm; GTM in extension, 3.8 ± 3.5 mm). In 18 of 20 (90%) cadaveric knees, the mean total GTM fell within the ±7.5-mm threshold. When comparing the actual measured TTL to the calculated TTL, there was a mean difference of 5.4 ± 3.9 mm. When comparing femoral tunnel drilling techniques, the total GTM for the accessory anteromedial portal technique was 2.1 ± 3.7 mm, while the total GTM for the flexible reamer technique was 3.6 ± 5.4 mm (P = .5). Conclusion: The N+10 rule resulted in an acceptable mean GTM in both flexion and extension. The mean difference between the measured versus calculated TTL using the N+10 rule was also acceptable. Clinical Relevance: The N+10 rule is a simple and effective intraoperative strategy for achieving desired TTL regardless of patient-specific factors to avoid excessive GTM in endoscopic BPTB ACLR using independent femoral tunnel drilling.

Vascular Complications in Sports Surgery: Diagnosis and Management.

Orthopedic sports surgery of the knee and shoulder is generally considered to be safe and effective. Vascular complications can occur during or after arthroscopy of either joint. A thorough understanding of anatomy, particularly when placing portals in non-routine locations, is extremely important. Prompt recognition of any vascular complication is of significant importance. This review will discuss the potential vascular complications for both knee and shoulder sports surgery, review the relevant anatomy, and discuss the treatment and expected outcome of each.

Use of antibiotic resistance analysis for representativeness testing of multiwatershed libraries.

The use of antibiotic resistance analysis (ARA) for microbial source tracking requires the generation of a library of isolates collected from known sources in the watershed. The size and composition of the library are critical in determining if it represents the diversity of patterns found in the watershed. This study was performed to determine the size that an ARA library needs to be to be representative of the watersheds for which it will be used and to determine if libraries from different watersheds can be merged to create multiwatershed libraries. Fecal samples from known human, domesticated, and wild animal sources were collected from six Virginia watersheds. From these samples, enterococci were isolated and tested by ARA. Based on cross-validation discriminant analysis, only the largest of the libraries (2,931 isolates) were found to be able to classify nonlibrary isolates as well as library isolates (i.e., were representative). Small libraries tended to have higher average rates of correct classification, but were much less able to correctly classify nonlibrary isolates. A merged multiwatershed library (6,587 isolates) was created and was found to be large enough to be representative of the isolates from the contributing watersheds. When isolates that were collected from the contributing watersheds approximately 1 year later were analyzed with the multiwatershed library, they were classified as well as the isolates in the library, suggesting that the resistance patterns are temporally stable for at least 1 year. The ability to obtain a representative, temporally stable library demonstrates that ARA can be used to identify sources of fecal pollution in natural waters.