• Journal of Korean Foot and Ankle Society
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• v.7 no.2
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• pp.166-173
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• 2003

Purpose: We assessed the treatment result of the distal chevron osteotomy in the patients with moderate to severe hallux valgus. Materials and Methods: In a total of 28 cases of hallux valgus in 20 patients, underwent distal chevron osteotomy between July 1999 and February 2001, were enrolled in this study. 21 cases were moderate and 7 cases were severe. The preoperative average hallux valgus angle and 1st-2nd intermetatarsal angle of the two groups were $31.5^{\circ}$, $15.8^{\circ}$ in moderate cases and $44.1^{\circ}$, $17.3^{\circ}$ in severe cases, respectively. Radiologic evaluation was done preoperatively, postoperatively and on the final follow-up visit using weight-bearing radiographic imaging to determine the hallux valgus angle and 1st-2nd intermetatarsal angle. Results: Radiographic evaluation revealed hallux valgus angle and 1st-2nd intermetatarsal angle in moderate cases to be $13.0^{\circ}$, $11.3^{\circ}$ (postoperatively and in severe cases $15.6^{\circ}$, $10.9^{\circ}C$, postoperatively. On final follow up, the results were $14.5^{\circ}$, $11.6^{\circ}$ in moderate cases and $18.3^{\circ}$, $11.9^{\circ}$ in severe cases, respectively. Conclusion: Distal chevron osteotomy can be usefully applied to the treatment of moderate to severe hallux valgus.

• Journal of Korean Foot and Ankle Society
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• v.1 no.2
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• pp.95-101
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• 1997

Hallux valgus has been characterized by a valgus deformity of the great toe at the metatarsophalangeal joint, along with medial deviation of the first metatarsal, and by three components. First, there is a valgus angle more than $20^{\circ}$ at the first, metatarsophalangeal joint. Second, there is a greater angle than $9^{\circ}$ between the first. and second metatarsals. Third, there is bursal hypertrophy at the medial eminence of the first metatarsals head. The etiology is multifactorial and many procedures have been reported in the treatment of hallux valgus. Most of the procedures are directed towards pain relief, correction of deformity, and preservation of dorsiflexion in the first metatarsophalangeal joint. One such treatment is the Modified chevron osteotomy. It is technically simple, and provides greater stability than a standard osteotomy, and allows early ambulation after surgery. We a reviewed 19 cases with 13 patients of hallux valgus deformity. They were all treated with the Modified chevron osteotomy at the Department of Orthopedic Surgery, Choong ang Gil Hospital, between June 1988 and May 1994. The results of the study were as follows; 1. The mean age was 36 years. Three patients(5 case) were male and ten patients(14 cases) were female. 2. The mean value of the hallux valgus angle was $34.1^{\circ}$, and the first to second intermetatarsal angle was $12.1^{\circ}$, preoperatively. These angles were corrected to $15.8^{\circ}$ and $8.5^{\circ}$, respectively. 3. The metatarsalgia subsided in 17 cases (89.5%). avascular necrosis, non union, and dorsal angulation complicatious were nonexistant. Early bone healing occurred in all cases. 4. The Modified chevron osteotomy is technically simple. It provides excellent pain relief, early ambulation, increased mechanical stability, and many avoids many complications such as AVN, non-union, and dorsal angulation.

• Transactions of the Korean hydrogen and new energy society
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• v.15 no.3
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• pp.194-200
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• 2004

Thermal energy performance of a brazed plate heat exchanger has been evaluated experimentally. The effects of plate pitch as well as chevron angle of a plate heat exchanger on the heat transfer rate and pressure drop have been investigated in the wide range as mass flow rates in detail. This problem is of particular interest in the design of a plate heat exchanger. The results obtained indicate that both heat transfer rate and pressure drop are increased as mass flow rate is increased, as expected. It is also found that the heat transfer rate is increased with a decrease in the plate pitch while the heat transfer is decreased with a decrease in the chevron angle. Friction factor correlations are suggested based on the measured pressure drop and effectiveness of plate heat exchangers are also compared.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.347-352
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• 2005

The objectives of this paper are to study the characteristics of heat transfer and pressure drop in plate heat exchangers for absorption applications, and to quantify the effect of mass flow rate, solution concentration, and geometric conditions such as chevron angle on the heat transfer coefficient and pressure drop in the plate heat exchangers. The working fluid is $H_2O$/LiBr solution with the LiBr concentration range of 53.2 - 62.5 % in mass. The results show that the overall heat transfer coefficient increases linearly with increasing Re. The heat transfer rate increases with increasing the chevron angle while it does not significantly depend on the LiBr concentration. The pressure drop also increases with increasing the chevron angle. The effect of the chevron angle on the pressure drop is more significant than that of the concentration.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.11
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• pp.1141-1148
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• 2001

Experiments on the condensation heat transfer and pressure drop in the brazed type plate heat exchangers are performed with refrigerants R410A/R22. To investigate the geometric effect, plate heat exchangers with the same pitch and height but different $45^{\circ},\;35^{\circ}and\;20^{\circ}$ chevron angles are used. Varying the mass flux of refrigerant (13~34 kg/$m^2$), the condensing temperatures ($20^{\circ}C\;and\;30^{\circ}C$) and the vapor quality (from 0.9 to 0.15) at the same constant heat flux ($5kW/m^2$), the condensation heat transfer coefficients and pressure drops are measured. The heat transfer coefficients decrease slightly with increasing the condensing temperature at a given mass flux in all plate heat exchangers. The pressure drop increases with increasing the mass flux and the quality and decreasing the condensing temperature and the chevron angle.

• Journal of Korean Foot and Ankle Society
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• v.9 no.2
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• pp.146-150
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• 2005

Purpose: We made a radiological comparison between $60^{\circ}$ distal Chevron osteotomy with short armed two parts and $40^{\circ}$ distal Chevron osteotomy with long armed one part performing operation in cases of hallux valgus angle of less than $40^{\circ}$, intermetatarsal angle of less than $15^{\circ}$. Materials and Methods: 12 cases with $60^{\circ}$ distal Chevron osteotomy and 12 cases with $40^{\circ}$ distal Chevron osteotomy were selected from October 2000 to March 2005. We have analysed the hallux valgus angle, 1-2 intermetatarsal angle, metatarsal length, distal metartarsal articular angle and angulation at osteotomy site on lateral view in each radiological films taken at preoperative, postoperative and 3 months after operation presuming bone union. All cases were women, both sides were 9 cases and average age was 52.3 years old. Results: Data taken at preoperative, postoperative and 3 months follow up films in $60^{\circ}$ distal Chevron osteotomy were as follows; the hallux valgus angles were $32.1^{\circ}$, $10.9^{\circ}$, $13.8^{\circ}$, the 1-2 intermetatarsal angles were $13.6^{\circ}$, $8.5^{\circ}$, $8.4^{\circ}$, the metatarsal length were 60.6 mm, 58.8 mm, 58 mm, the distal metartarsal articular angles were $13^{\circ}$, $6^{\circ}$, $6.6^{\circ}$ and 3 cases were over $3^{\circ}$ angulation at lateral view. In $40^{\circ}$ distal Chevron osteotomy, the hallux valgus angles were $34.5^{\circ}$, $11.6^{\circ}$, $15.3^{\circ}$, the 1-2 intermetatarsal angles were $12.7^{\circ}$, $8.2^{\circ}$, $7.8^{\circ}$, the metatarsal length were 59.2 mm, 56.9 mm, 55.9 mm, the distal metartarsal articular angles were $12^{\circ}$, $7.3^{\circ}$, $7.3^{\circ}$ and there were no case with angulation over $3^{\circ}$ at lateral view. Conclusion: In comparison between $60^{\circ}$ distal Chevron osteotomy and $40^{\circ}$ distal Chevron osteotomy measuring at postoperative and follow up, most of all data were similar, but 3 cases over $3^{\circ}$ angulation at lateral view happened in $60^{\circ}$ Chevron osteotomy. This result showed that $40^{\circ}$ distal Chevron osteotomy fixing with screws through long armed one part may have benefit than $60^{\circ}$ distal Chevron osteotomy fixing with K-wires through short armed two parts in making rigid fixation, even though there is a personal difference of technigue.

• Journal of Korean Foot and Ankle Society
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• v.19 no.3
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• pp.91-96
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• 2015

Purpose: The purpose of this study is to evaluate the sequential changes of clinical and radiographic results after proximal chevron osteotomy in patients with moderate to severe hallux valgus. Materials and Methods: Between January 2008 and December 2009, 93 patients (117 feet) were treated with proximal chevron osteotomy and distal soft tissue procedure for symptomatic moderate to severe hallux valgus deformity. The mean age of patients was 51 years (range, 19 to 71) and the mean duration of follow-up was 27.5 months (range, 24 to 35). Clinical results were evaluated using visual analogue scale (VAS) and American Orthopaedic Foot and Ankle Society (AOFAS) score preoperatively, at 3, 6, and 12 months after surgery, and at the last follow-up. Radiographic parameters including hallux valgus angle, intermetatarsal angle, and sesamoid position were evaluated preoperatively, immediately postoperatively, at 6 weeks, at 3, 6, and 12 months after surgery, and at the last follow-up. Results: VAS and AOFAS score showed significant improvement until 12 months after surgery. Hallux valgus angle and sesamoid position stabilized at 12 months after surgery and intermetatarsal angle stabilized at 6 months after surgery. Conclusion: Clinical and radiographic results were stabilized beyond 12 months after proximal chevron osteotomy in patients with moderate to severe hallux valgus.

• Journal of Korean Foot and Ankle Society
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• v.16 no.1
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• pp.31-37
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• 2012

Purpose: The purpose of our study is the comparison of radiological and clinical outcomes between modified distal chevron osteotomy and proximal metatarsal osteotomy for the patients who had moderate to severe hallux valgus deformity. Materials and Methods: In this retrospective study, we included 54 patients (65 feets) who underwent the operation of moderate to severe hallux valgus in our hospital from May 2007 to August 2010. Our study compares two groups. For Group 1, a modified distal chevron osteotmy and a distal soft tissue procedure were done and for Group 2, a proximal metatarsal osteotmy and a distal soft tissue procedure were done. The group 1 were 29 feets; the group 2 were 36 feets, and the average follow up was 9 months. Results: The radiological results show that the hallux valgus angle and the first-second intermetatarsal angle were significantly decreased in two groups. In each parameter, the correction of the hallux valgus angle was $19.1^{\circ}$ (Group 1) and $24.3^{\circ}$ (Group 2), the correction of the first-second intermetatarsal angle was $9.6^{\circ}$ (Group 1) and $10.3^{\circ}$ (Group 2). Shortening of the first metatarsal length was 0.87 mm (Group 1) and 0.77 mm (Group 2). There are no significant clinical results (American Orthopaedic Foot and Ankle Society score, AOFAS score) in two groups. Conclusion: It is thought that a modified distal chevron osteotomy and a distal soft tissue procedure are a considerable operative treatment of moderate to severe hallux valgus deformity because of the similar cilinical results, more simple operative techniques, and less complications than a proximal metatarsal osteotomy.

• Journal of Korean Foot and Ankle Society
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• v.11 no.2
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• pp.154-159
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• 2007

Purpose: The purpose of the present study is to evaluate the proximal metatarsal chevron osteotomy outcomes for moderate to severe hallux valgus more than seven year follow up. Materials and Methods: Between 1996 and 1998, hallux valgus 61 cases were evaluated. The follow up period was more than seven years. The clinical review analyzed by the hallux metatarsophalangeal-interphalangeal scale of the American Orthopedic Foot and Ankle Society, radiologic review by the hallux valgus angle, first and second intermetatarsal angle. Complication also evaluated. Results: Clinically, preoperative AOFAS score was average 43 points (range; $16{\sim}60$ points) which significantly improved to 88 points (range; $61{\sim}100$ points) at last follow up periods. Radiologically, the mean preoperative, postoperative, last follow up hallux valgus angle was $34^{\circ}$, $5.2^{\circ}$, $10.9^{\circ}$. The mean preoperative, postoperative, last follow up intermetatarsal angle was $15.3^{\circ}$, $3.3^{\circ}$, $5.3^{\circ}$. Postoperative angle change were no statistical significance (p>0.05). Complication were hallux varus 6 cases, metatarsophalangeal joint arthritis 2 cases, recurrence 1 case. Conclusion: Proximal metatarsal chevron osteotomy shows satisfactory outcome for moderate to severe hallux valgus more than seven year follow up.

• Journal of Korean Foot and Ankle Society
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• v.12 no.2
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• pp.140-144
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• 2008

Purpose: The purpose of this study is to compare the treatment outcomes of distal chevron osteotomy with those of proximal metatarsal closing wedge osteotomy in patients with moderate severity hallux valgus. Materials and Methods: Forty-two patients (51 feet) who were underwent either distal chevron osteotomy (Group I, 22 patients, 27 feet) or proximal metatarsal closing wedge osteotomy (Group II, 20 patients, 24 feet) for the correction of moderate hallux valgus deformity were evaluated retrospectively. We assessed the radiographic results with several parameters including hallux valgus angle (HVA), intermetatarsal angle (IMA) and distal metatarsal articular angle (DMAA). And clinical results with modified AOFAS score at last follow-up. Results: There were no significant differences in IMA, HVA and DMAA between two groups preoperatively. We can achieve the good results with both procedures, but mean HVA and IMA of group II was significantly lower than those of group I. There was some loss of correction in group I at the last follow-up. There was no significant difference in clinical results according to modified AOFAS scoring between two groups at the last follow-up. Conclusion: The proximal metatarsal closing wedge osteotomy for the hallux valgus with moderate severity is better treatment option to achieve better radiographic correction and to prevent loss of correction or recurrence than distal chevron osteotomy.