The metastatic spread of tumor cells to distant sites represents the major cause of cancer-related deaths. Cancer metastasis involves a series of complex interactions between tumor cells and microenvironment that influence its biological effectiveness and facilitate tumor cell arrest to distant organs. More than a century since Paget developed the theory of seed and soil, the enigma of tissue specificity observed in metastatic colonization of tumor cells begins to unfold itself. The advent of new technologies has led to the discovery of novel molecules and pathways that confer metastasis-associated properties to the cancer cells, mediating organ specificity and unique genetic signatures have been developed using microarray studies. Future clinical studies and new antimetastatic compounds aiming to improve survival of patients with metastasis will most probably be based on these signatures. This review summarizes the plethora of old and new molecules that are strongly correlated with organ-specific metastases and which provide now an identity to the theory of seed and soil.
Purpose Although total knee arthroplasty (TKA) is regularly associated with favorable outcomes, considerable research efforts are still underway to improve its ability to achieve a neutral postoperative mechanical axis. Patientspecific instrumentation (PSI) was introduced with this and other goals in mind. The current retrospective study was designed to determine whether PSI would lead to a hipknee-ankle angle (HKA) within ±3°of the ideal alignment of 180°. Methods A long-leg x-ray of the knee was performed after an average of 3.5 months (SD, three to four months), following 124 TKAs performed by a single surgeon using PSI technology (VISIONAIRE; Smith & Nephew). In addition to HKA, the zone of the mechanical axis (ZMA; zone of the tibial base plate where the mechanical axis of the limb intersects with the tibial base plate) was analysed, with the ideal intersection occurring centrally. Results There were 100 knees (average age, 66.8 years) with follow-up data available. The average HKA changed from 175.5±5.6°preoperatively to 178.5±1.7°postopera-tively. The rate of ±3°and ±5°HKA outliers was 11 % and 3 %, respectively. In terms of ZMA, the mechanical axis passed through the central third of the knee in the majority of cases (93 knees, 93 %). There were no intra-operative complications with the use of PSI.Conclusions The use of PSI technology was able to achieve a neutral mechanical axis on average in patients undergoing TKA. Further follow-up will be needed to ascertain the long-term impact of these findings.
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