Publications

PURPOSE

Recent anatomic studies have suggested that the dominant arterial supply of the patella enters through the inferior pole. Based upon these findings, we hypothesized that bone-patellar tendon-bone graft harvest can significantly diminish patellar vascularity.

METHODS

Nine matched pair cadaveric knee specimens (mean age 47.4 years) were dissected and cannulated. A single knee was selected to undergo routine graft harvest, and the contralateral knee was left intact to serve as a control. Gadolinium was injected, and magnetic resonance imaging (MRI) signal enhancement was quantified to determine differences in uptake. Each matched pair was subsequently injected with a urethane polymer compound and dissected to correlate vessel disruption with MRI findings.

RESULTS

We identified two predominating patterns of vessel entry. In one pattern, the vessel entered the inferomedial aspect (five o'clock/right, seven o'clock/left) of the patella and was disrupted by graft harvest in 2/9 (22.2 %) pairs. In the second pattern, the vessel entered further medial (four o'clock/right, eight o'clock/left) and was not disrupted (7/9, 78.8 %). The mean decrease in gadolinium uptake following disruption of the predominant vessel measured 56.2 % (range 42.6-69.5 %) compared to an average decrease of 18.3 % (range 7.1-29.1 %) when the dominant arterial supply to the inferior pole remained intact (p < 0.04).

CONCLUSION

Medial entry of the predominant vessel precluded vessel disruption. Disruption of the dominant arterial supply can result in a significant decrease in patellar vascularity. Modification of graft harvest techniques and areas of surgical dissection should be explored to minimize vascular insult. Further correlation with clinical studies/outcomes is necessary to determine a potential association between vascular insult and anterior knee pain.

The transcontinental spread of multidrug-resistant (MDR) tuberculosis is poorly characterized in molecular epidemiologic studies. We used genomic sequencing to understand the establishment and dispersion of MDR Mycobacterium tuberculosis within a group of immigrants to the United States. We used a genomic epidemiology approach to study a genotypically matched (by spoligotype, IS6110 restriction fragment length polymorphism, and mycobacterial interspersed repetitive units-variable number of tandem repeat signature) lineage 2/Beijing MDR strain implicated in an outbreak of tuberculosis among refugees in Thailand and consecutive cases within California. All 46 MDR M. tuberculosis genomes from both Thailand and California were highly related, with a median difference of 10 single-nucleotide polymorphisms (SNPs). The Wat Tham Krabok (WTK) strain is a new sequence type distinguished from all known Beijing strains by 55 SNPs and a genomic deletion (Rv1267c) associated with increased fitness. Sequence data revealed a highly prevalent MDR strain that included several closely related but distinct allelic variants within Thailand, rather than the occurrence of a single outbreak. In California, sequencing data supported multiple independent introductions of WTK with subsequent transmission and reactivation within the state, as well as a potential super spreader with a prolonged infectious period. Twenty-seven drug resistance-conferring mutations and 4 putative compensatory mutations were found within WTK strains. Genomic sequencing has substantial epidemiologic value in both low- and high-burden settings in understanding transmission chains of highly prevalent MDR strains.