단섬유 강화 플라스틱의 유변학적 물성 및 웰드라인을 가지는ties of Short Fiber Reinforced Plastics and Mechanical Properties of Injection Molded Articles with Weld-lines

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Unstable Lateral Hinge Fracture or Occult Complete Osteotomy Adversely Affects Correction Accuracy in Open-Wedge High Tibial Osteotomy

Purpose: To verify whether lateral hinge fracture (LHF) affects correction accuracy in open-wedge high tibial osteotomy (OWHTO) and to identify the fracture characteristics responsible for inaccurate correction, including LHF type and hinge location. Methods: Patients undergoing OWHTO with locking plate fixation between 2010 and 2016 were retrospectively reviewed. Patients who did not have a minimum 2-year of follow-up or postoperative long-standing hip-to-ankle radiographs were excluded. Correction accuracy was assessed using the weight-bearing line ratio: 57% to 67%, planned correction; 50% to 70%, acceptable correction; otherwise, inappropriate correction. The association between LHF and correction accuracy was assessed using the c2 test. To identify the fracture characteristics responsible for inaccurate correction, LHF type (stable type 1 and unstable types 2 and 3) and hinge location (shallow osteotomy, deep osteotomy, and occult complete osteotomy) were analyzed using ordinal logistic regression analysis, taking other related demographic and radiologic factors into account. Clinical outcomes according to LHF type were evaluated using the Hospital for Special Surgery scores. Results: A total of 148 cases were included; 41 (27.7%) showed LHF: type 1, 32 cases; type 2, 7 cases; and type 3, 2 cases. Planned, acceptable, and inappropriate corrections were noted in 63 (42.6%), 36 (24.3%), and 48 (32.4%) cases, respectively. LHF had a significant association with correction accuracy (P = .010). Regarding fracture characteristics, unstable LHF and occult complete osteotomy were significant risk factors (P = .016 and P = .004, respectively). Specifically in cases of stable LHF, occult complete osteotomy adversely affected correction accuracy (P = .025). No difference was found in the final Hospital for Special Surgery scores according to LHF type (P = .816). Conclusions: LHF affected the accuracy of coronal alignment correction in OWHTO. Unstable LHF or occult complete osteotomy were risk factors for inaccurate correction. Even among stable LHFs, those with occult complete osteotomy could lead to inaccurate correction. Level of Evidence: Level III, retrospective cohort study

A New Error Compensation Method in Linear Encoder Using a Phase-Modulated Grating

A new hardware compensation method reducing displacement measurement errors, caused by tilt of index scale in moire linear encoders, has been developed. In conventional moire linear encoders, the detectors are aligned perpendicular to the line of moire fringes this structure is very sensitive to an unwanted tilt of the gratings. In this paper, a newly designed grating, called a phase-modulated grating, is developed to compensate for non-orthogonal errors. By using the phase-modulated grating instead of a conventional index, it is possible to reduce non-orthogonal errors of moire linear encoders

Development of a new error compensation method in linear encoder using phase shifted grating

학위논문(석사) - 한국과학기술원 : 기계공학과, 1999.2, [ iv, 48 p. ]한국과학기술원 : 기계공학과

Cartilage Status, Rather Than Chronologic Age, Determines the Outcomes of Open Wedge High Tibial Osteotomy: A Cartilage StatuseMatched Cohort Study

Purpose: To evaluate the true effects of chronologic age on the clinical and radiologic outcomes of open wedge high tibial osteotomy (OWHTO) in a sample of patients who had been matched according to cartilage status in the medial and lateral compartments. Methods: The records of 107 OWHTO cases were reviewed. To evaluate potential differences in the outcomes according to age, the subjects were divided into 2 groups by the median age: older group and younger group. The Hospital for Special Surgery scores and Knee Society objective and functional scores before surgery and at the latest follow-up were compared between the groups. Then, the subjects in each group were matched 1:1 according to cartilage status in the medial and lateral compartments, which had been evaluated during arthroscopy prior to the osteotomy. The clinical scores were compared between the matched groups. The change in the medial joint space width (DJSW) from 6 to 12 months postoperatively to the latest follow-up was also compared before and after matching. Results: With a median age of 55 years, 44 and 63 cases were allocated into the older and younger groups, respectively. Prior to cartilage status matching, the latest Hospital for Special Surgery and Knee Society functional scores were significantly higher in the older group (P ¼ .042 and P ¼ .025, respectively). After matching, each group included 41 cases, and the differences in these clinical scores were no longer significant (P ¼ .164 and P ¼ .165, respectively). No difference in DJSW was observed between the groups, regardless of matching status (P ¼ .901 before matching, P ¼ .979 after matching). Conclusions: The clinical outcomes of OWHTO were affected by cartilage status, rather than by the chronologic age itself. No difference was observed in the radiologic outcome (DJSW) with respect to age. OWHTO should not be waived in treating elderly patients without highly advanced cartilage degeneration simply because of their chronologic ages. Level of Evidence: Level III, retrospective cohort study

Learning Curve For Lateral Meniscal Allograft Transplantation: Preventing Meniscal Extrusion

Purpose: This study analyzes the large number of lateral meniscal allograft transplantation (LMAT) procedures conducted by a single surgeon over 23 years to determine whether the absolute amount of graft subluxation and the incidence of extrusion are different at the present time compared to the early MAT era. Methods: We reviewed 320 cases of LMAT performed by a single surgeon between 1996 and 2019. This cohort was chronologically divided into 8 groups (of 40 subjects). The absolute amount of subluxation was measured by the coronal sections of magnetic resonance images taken 1 year after operation. Subluxation by more than 3 mm was considered as extrusion. The graft extrusion learning curve was plotted in each series using the learning curve cumulative summation test (LC-CUSUM). Results: Extrusion incidence was 41.6%, and the mean absolute amount of graft subluxation was 3.4 +/- 2.2 mm for all subjects. There were significant between-group differences in extrusion incidence and absolute amount of graft subluxation (extrusion incidence, P < .001; absolute amount of graft subluxation, P < .001), and the extension incidence and graft subluxation decreased from Group I (72.5%, 4.6 +/- 1.7) to Group VIII (27.5%, 2.5 +/- 2.1). LC-CUSUM analysis signaled that the surgeon had achieved predefined acceptable outcomes in avoiding extrusion after 128 cases. Conclusion: The incidence of extrusion and absolute amount of graft subluxation decreased significantly over a period of 23 years, and the surgeon achieved a certain level of proficiency after 128 cases. Level of Evidence: Level IV, Case series