Jin Woo Lee

BACKGROUND: Identifying factors associated with favorable or unfavorable outcomes would provide patients with accurate expectations of the arthroscopic marrow stimulation techniques. PURPOSE: To investigate the prognostic significance and optimal measures of defect size in osteochondral lesion of the talus as treated with arthroscopy. HYPOTHESIS: A critical, or threshold, defect size may exist at which clinical outcomes become poor in the treatment of osteochondral lesion of the talus. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: In sum, 120 ankles underwent arthroscopic marrow stimulation treatment for osteochondral lesion of the talus and were evaluated for prognostic factors. Clinical failure was defined as patients' having osteochondral transplantation or an American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot Scale score less than 80. Linear regression analysis and the Kaplan-Meier method were used to identify optimal cutoff values of defect size. RESULTS: Eight ankles (6.7%) required osteochondral transplantation, and 22 ankles (18.4%) were considered failures because of AOFAS scores less than 80, which indicated fair or poor results. Linear regression analysis showed a high prognostic significance of defect area and suggested a cutoff defect size of 150 mm(2) for the optimum identification of poor clinical outcomes (P < .001). Only 10 of 95 ankles (10.5%) with a defect area <150 mm(2) showed clinical failure, whereas in patients with an area >or=150 mm(2), the clinical failure rate was significantly higher (80%, 20/25). There was no association between outcome and the patient's age, duration of symptoms, trauma, associated lesions, and location of lesions (P > .05). CONCLUSION: Initial defect size is an important and easily obtainable prognostic factor in osteochondral lesions of the talus and so may serve as a basis for preoperative surgical decisions. A cutoff point exists regarding the risk of clinical failure at a defect area of approximately 150 mm(2) as calculated from magnetic resonance imaging.

We present a motion planner for autonomous highway driving that adapts the state lattice framework pioneered for planetary rover navigation to the structured environment of public roadways. The main contribution of this paper is a search space representation that allows the search algorithm to systematically and efficiently explore both spatial and temporal dimensions in real time. This allows the low-level trajectory planner to assume greater responsibility in planning to follow a leading vehicle, perform lane changes, and merge between other vehicles. We show that our algorithm can readily be accelerated on a GPU, and demonstrate it on an autonomous passenger vehicle.

Interpenetrating polymer network (IPN) hydrogels composed of chitosan and poly(acrylic acid) (PAAc) were synthesized by UV irradiation method, and their structure, crystallinity, swelling behavior, thermal property, and mechanical property were investigated. Chitosan/PAAc IPNs exhibited relatively high equilibrium water content and also showed reasonable sensitivity to pH. From the swelling behaviors at various pH's, Fourier transform infrared spectra at high temperature and thermal analysis confirmed the formation of polyelectrolyte complex due to the reaction between amino groups in chitosan and carboxyl groups in PAAc. For this reason, even at a swollen state, the present chitosan/PAAc IPNs possess good mechanical properties. Particularly, the CA-2 sample (with a weight ratio of chitosan/PAAc = 50/50, molar ratio [NH2]/[COOH] = 25/75) showed the lowest equilibrium water content and free water content, attributed to the more compact structure of the polyelectrolyte than CA-1 or CA-3 due to the high amount of interchain bond within the IPN. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 113–120, 1999

Background: The critical lesion size treated with bone marrow stimulation (BMS) for osteochondral lesions of the talus (OLTs) has been 150 mm 2 in area or 15 mm in diameter. However, recent investigations have failed to detect a significant correlation between the lesion size and clinical outcomes after BMS for OLTs. Purpose: To systematically review clinical studies reporting both the lesion size and clinical outcomes after BMS for OLTs. Study Design: Systematic review. Methods: A systematic search of the MEDLINE and EMBASE databases was performed in March 2015 based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Included studies were evaluated with regard to the level of evidence (LOE), quality of evidence (QOE), lesion size, and clinical outcomes. Results: Twenty-five studies with 1868 ankles were included; 88% were either LOE 3 or 4, and 96% did not have good QOE. The mean area was 103.8 ± 10.2 mm 2 in 20 studies, and the mean diameter was 10.0 ± 3.2 mm in 5 studies. The mean American Orthopaedic Foot and Ankle Society score improved from 62.4 ± 7.9 preoperatively to 83.9 ± 9.2 at a mean 54.1-month follow-up in 14 studies reporting both preoperative and postoperative scores with a mean follow-up of more than 2 years. A significant correlation was found in 3 studies, with a mean lesion area of 107.4 ± 10.4 mm 2 , while none was reported in 8 studies, with a mean lesion area of 85.3 ± 9.2 mm 2 . The lesion diameter significantly correlated with clinical outcomes in 2 studies (mean diameter, 10.2 ± 3.2 mm), whereas none was found in 2 studies (mean diameter, 8.8 ± 0.0 mm). However, the reported lesion size measurement method and evaluation method of clinical outcomes widely varied among the studies. Conclusion: An assessment of the currently available data does suggest that BMS may best be reserved for OLT sizes less than 107.4 mm 2 in area and/or 10.2 mm in diameter. Future development in legitimate prognostic size guidelines based on high-quality evidence that correlate with outcomes will surely provide patients with the best potential for successful long-term outcomes.