Extraarticular Knee Resection for Sarcomas with Preservation of the Extensor Mechanism: Surgical Technique and Review of Cases

BACKGROUND: Sarcomas in or contaminating the knee are rare but extremely challenging to treat. Complete resection of the joint is necessary, and often the entire extensor mechanism is removed as well. Reconstruction of the knee is challenging, and the resulting function may be compromised. DESCRIPTION OF TECHNIQUE: We describe a surgical technique of extraarticular resection of the knee while preserving the extensor mechanism combined with prosthetic reconstruction. The medial and lateral retinaculum is prepared such that it allows extraarticular placement of K-wires that are driven through the patella and the proximal tibia, serving as in situ guides for the osteotomies. PATIENTS AND METHODS: We retrospectively reviewed 11 patients with sarcomas contaminating the knee. The minimum followup was 14 months (mean, 38 months; range, 14-80 months). RESULTS: At last followup patients had a mean flexion of 88° (range, 65°-120°). We observed no complications related to the extensor mechanism, and there was one local recurrence. CONCLUSIONS: We believe extraarticular resection of the knee with preservation of the extensor mechanism is a reasonable treatment option for intraarticular sarcomas with functional scores comparable to those for patients having intraarticular resections. LEVEL OF EVIDENCE: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence

Accuracy of Patient Specific Cutting Blocks in Total Knee Arthroplasty

Background. Long-term survival of total knee arthroplasty (TKA) is mainly determined by optimal positioning of the components and prosthesis alignment. Implant positioning can be optimized by computer assisted surgery (CAS). Patient specific cutting blocks (PSCB) seem to have the potential to improve component alignment compared to the conventional technique and to be comparable to CAS. Methods. 113 knees were selected for PSI and included in this study. Pre- and postoperative mechanical axis, represented by the hip-knee-angle (HKA), the proximal tibial angle (PTA), the distal femoral angle (DFA), and the tibial slope (TS) were measured and the deviation from expected ideal values was calculated. Results. With a margin of error of ±3°, success rates were 81.4% for HKA, 92.0% for TPA, and 94.7% for DFA. With the margin of error for alignments extended to ±4°, we obtained a success rate of 92.9% for the HKA, 98.2% for the PTA, and 99.1% for the DFA. The TS showed postoperative results of 2.86 ± 2.02° (mean change 1.76 ± 2.85°). Conclusion. PSCBs for TKA seem to restore the overall leg alignment. Our data suggest that each individual component can be implanted accurately and the results are comparable to the ones in CAS

Opportunities, Rational Choice, and Self-Control On the Interaction of Person and Situation in a General Theory of Crime

Seipel C, Eifler S. Opportunities, Rational Choice, and Self-Control On the Interaction of Person and Situation in a General Theory of Crime. CRIME & DELINQUENCY. 2010;56(2):167-197.In this article, deviant action is analyzed on the basis of ideas derived from Gottfredson and Hirschi's self-control theory. Presumedly, self-control in interaction with opportunities can explain deviant action. This assumption is elaborated using the concept of high- and low-cost situations from rational choice theory. From this point of view, the hypotheses are that self-control predicts deviant action in low-cost situations, whereas utility predicts deviant action in high- cost situations. Two test strategies are employed in an empirical examination of these hypotheses. A standardized questionnaire was presented to a sample of 494 German adults aged 18 to 80. The results of both test strategies show that the assumptions of an interaction effect between self-control and opportunities are fundamentally supported