• Korean Journal of Applied Biomechanics
• /
• v.26 no.2
• /
• pp.167-174
• /
• 2016

Objective: The purpose of this study was to determine the interrelationship between ranges of motion of the knee and ankle joints on the sagittal plane and the attenuation magnitude of impact shock at high frequency (9~20 Hz) in the support phase during downhill running. Method: Fifteen male heel-toe runners with no history of lower extremity injuries were recruited for this study (age, $25.07{\pm}5.35years$; height, $175.4{\pm}4.6cm$; mass, $75.8{\pm}.70kg$). Two uniaxial accelerometers were mounted to the tuberosity of tibia and sacrum, respectively, to measure acceleration signals. The participants were asked to run at their preferred running speed on a treadmill set at $0^{\circ}$, $7^{\circ}$, and $15^{\circ}$ downhill. Six optical cameras were placed around the treadmill to capture the coordinates of the joints of the lower extremities. The power spectrum densities of the two acceleration signals were analyzed and used in the transfer function describing the gain and attenuation of impact shock between the tibia and the sacrum. Angles of the knee and ankle joints on the sagittal plane and their angle ranges were calculated. The Pearson correlation coefficient was used to test the relationship between two variables, the magnitude of impact shock, and the range of joint angle under three downhill conditions. The alpha level was set at .05. Results: Close correlations were observed between the knee joint range of motion and the attenuation magnitude of impact shock regardless of running slopes (p<.05), and positive correlations were found between the ranges of motion of the knee and ankle joints and the attenuation magnitude of impact shock in $15^{\circ}$ downhill running (p<.05). Conclusion: In conclusion, increased knee flexion might be required to attenuate impact shock during downhill and level running through change in stride or cadence while maintaining stability, and strong and flexible ankle joints are also needed in steeper downhill running.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.32 no.5
• /
• pp.502-508
• /
• 2012

Quantitative ultrasound technologies for osteoporosis diagnosis measure ultrasonic parameters such as speed of sound(SOS) and normalized broadband ultrasound attenuation(nBUA) in the calcaneus (heel bone). In the present study, the dependences of SOS and nBUA on bone mineral density in the proximal femur with high risk of fracture were investigated by using 20 trabecular bone samples extracted from bovine femurs. SOS and nBUA in the femoral trabecular bone samples were measured by using a transverse transmission method with one matched pair of ultrasonic transducers with a center frequency of 1.0 MHz. SOS and nBUA measured in the 20 trabecular bone samples exhibited high Pearson's correlation coefficients (r) of r = 0.83 and 0.72 with apparent bone density, respectively. The multiple regression analysis with SOS and nBUA as independent variables and apparent bone density as a dependent variable showed that the correlation coefficient r = 0.85 of the multiple linear regression model was higher than those of the simple linear regression model with either parameter SOS or nBUA as an independent variable. These high linear correlations between the ultrasonic parameters and the bone density suggest that the ultrasonic parameters measured in the femur can be useful for predicting the femoral bone mineral density.

• Journal of the Korean Society of Radiology
• /
• v.6 no.5
• /
• pp.343-349
• /
• 2012

Intensity Modulated Radiotherapy (IMRT) is increasing its use recently due to its benefits of minimizing the dose on surrounding normal organs and being able to target a high dose specifically to the tumor. The study aims to measure and evaluate the dose distribution according to its dynamic changes in Mapcheck. In order to verify the dose distribution by EDW angle($10^{\circ}$,$15^{\circ}$,$20^{\circ}$,$25^{\circ}$,$30^{\circ}$,$45^{\circ}$,$60^{\circ}$), field size (asymmetric field) and depth changes (1.5 cm, 5.0 cm) using IMRT in Clinac ix, a solid phantom was placed on the Mapcheck and 100MU was exposed by 6 MV, 10MV X-ray. Using a 6MV, 10MV energy, the percentage depth dose according to a dynamic changes at a maximum dose depth (1.5 cm) and at 5.0 cm depth showed the value difference of maximum 0.6%, less than 1%, which was calculated by a treatment program device considering the maximum dose depth at the center as 100%, the percentage depth dose was in the range between 2.4% and 7.2%. Also, the maximum value difference of a percentage depth dose was 4.1% in Y2-OUT direction, and 1.7% in Y1-IN direction. When treating a patient using a wedge, it is considered that using an enhanced dynamic wedge is effective to reduce the scattered dose which induces unnecessary dose to the surroundings. In particular, when treating a patient at clinic, a treatment must be performed considering that the wedge dose in a toe direction is higher than the dose in a heel direction.

• Journal of the Korean Orthopaedic Association
• /
• v.53 no.6
• /
• pp.522-529
• /
• 2018

Purpose: To compare the clinical outcomes of ultrasound-guided percutaneous repair (USPR) and open repair in a ruptured Achilles tendon. Materials and Methods: The outcomes of 12 patients with USPR (group A) and 18 patients with open repair (group B) from January 2015 to February 2017 were analyzed retrospectively. The postoperative clinical evaluations were performed using the Arner-Lindholm scale, American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, Achilles tendon total rupture score (ATRS), and visual analogue scale for the overall satisfaction and cosmetic satisfaction with the scar, and the starting time of single heel raises. The complications were also evaluated. Results: The Arner-Lindholm scale, AOFAS ankle-hindfoot score, ATRS, starting time of single heel raises were similar in both groups (all p>0.05). Group A showed a significantly higher overall patient's satisfaction and cosmetic satisfaction in than group B (all p<0.05). Two cases of Achilles tendon elongation were encountered in group A, and 1 case of re-rupture with deep infection and 1 case of superficial infection were experienced in group B. Conclusion: USPR showed good clinical outcomes and high satisfaction as well as a low rate of complications, such as sural nerve injury. Therefore, USPR can be considered as an effective surgical treatment option for Achilles tendon ruptures.

• The Journal of Korean Orthopaedic Ultrasound Society
• /
• v.5 no.2
• /
• pp.75-80
• /
• 2012

Purpose: The purpose of this study is to evaluate the usefulness of ultrasonographic examination for diagnosis and removal of small sized foreign bodies, which invaded extremity but difficulty to find on physical examination and/or plane radiographs. Materials and Methods: Since March, 2009 to February, 2012, we performed preoperatively ultrasonography and operation in 9 cases of foreign bodies of hand or foot. Mean symptom duration periods was 32 months. The location were fingers in 5, palms in 2, hand dorsum in 1, heel in 1 case. In 2 cases, foreign bodies were seen on plane radiographs. In the remaining 7 cases, foreign bodies could be diagnosed by ultrasonography only. Using high resolution stick probe, we performed evaluation on size, location, character of foreign bodies and compared preoperative ultrasonographic findings to intraoperative ones. Results: The site of foreign bodies in preoperative ultrasonography corresponded well with intraoperative findings. Foreign bodies were glass particles in 5, plant thorns in 4, pencil lead in 1. Mean size was 3.9 mm (2~7 mm). Conclusion: Ultrasonography is usefull evaluation tool for diagnosis and treatment in whom residual foreign bodies were suspected.

• Korean Journal of Applied Biomechanics
• /
• v.18 no.2
• /
• pp.1-9
• /
• 2008

The purpose of this study was to investigate the effect of different obstacle heights on the plantar foot pressure during obstacle crossing. Sixteen healthy adults who had no musculoskeletal disorders were instructed to perform unobstructed level walking and to step over obstacles corto 10cm, 20cm, 30cm. Plantar foot forces and pressures were recorded by the Footmat system(Tekscan, Boston, USA) during level and obstacle walking with barefoot. Plantar foot surface was defined as seven regions for pressure measurement; two toe regions, three forefoot regions, one midfoot region, one heel region. One-way ANOVA was used to compare each region data of foot according to various heights. The results indicated that there are significant differences on peak pressure and maximal forces regarding each region at stance phase. As height of obstacle became high, the pathway of COP had a tendency to be short and abducted. Plantar pressure of foot could be changed by obstacle height and these findings demonstrated that obstacle with different height have an effect on structure and function of the foot.

• Journal of Korean Foot and Ankle Society
• /
• v.9 no.2
• /
• pp.173-178
• /
• 2005

Propose: There have been many debates about the ideal surgical technique for acute Achilles tendon rupture. The purpose of this study is to review and analyze the clinical outcome of the acute Achilles tendon ruptures that had been repaired by indirect suture technique with minimal incision that utilized an instrument called Achillon (Newdeal, France). Materials and Methods: This study is based on the 14 cases (14 patients) of acute Achilles tendon total ruptures that have been repaired by minimal incision technique utilizing Achillon instrument from June 2003 to December 2004. Two cases were reruptured before 8 weeks and repaired again using Krackow suture which left 12 feet for postoperative functional evaluation with at least 6 months of follow-up. Ten cases were men and average age at time of injury was 34.4 (26-49) years. The time from injury to surgery was an average of 4.5 (1-9) days and the postoperative evaluations were done by an Arner-Lindholm scale and AOFAS score. The ability to return to original work and sports activities as well as patient satisfaction were also evaluated. Results: The follow-up period was averaged for 13.2 (6-24) months. Seventy-one percent of cases were ruptured during sports activities. The ruptured level was the average of 5.1 cm (3.2-8 cm) above calcaneal attachment and the skin incision was averaged for 2.7 cm (2.5-3.0 cm) long. At final follow-up, standing on tip-toe was possible in all cases while the heel-floor height on ruptured side was shorter by 0.7 cm (0-2 cm). By Arner-Lindholm evaluation scale, 9 cases were excellent, and 3 cases were good. Overall AOFAS score was an average of 96.1 (94-100), and all patients were satisfied with the result. Patients returned to work at an average of 1.3 months after the surgery and pre-injury sports activities were all possible from at 6 months after operation. Conclusion: Since we have treated acute Achilles tendon ruptures with minimal incision technique utilizing the Achillon and gained encouraging functional results with all patients returning to previous work with high patient satisfaction, this technique could be recommended as one of the ideal surgical options for the Achilles tendon ruptures.

• The Journal of the Korean bone and joint tumor society
• /
• v.6 no.2
• /
• pp.69-76
• /
• 2000

Purpose : Tumors of the foot and ankle are uncommon compared with those arising in the other sites, and the malignant tumors are rare. We analyzed the data of patients who have been diagnosed as having a tumor of the foot and ankle. Materials and Methods : Between 1989 and 1998, we treated 72 patients and analyzed on their clinical characteristics retrospectively. Results : Fifty-three cases were benign. Included are 30 cases of soft tissue tumor and 23 cases of bone tumor. Malignant tumor was in 19 cases (26%), including 17 cases of soft tissue tumor, one cases of metastatic tumor. The most common benign tumor was fibroma in soft tissue and osteochondroma in bone. Malignant melanoma was the most common malignant tumor of the foot (7 cases). The predilection site for benign tumors was around toes while for the malignant tumor mostly arises in the heel. Among 19 malignant tumors, local recurrence developed in 3 cases and the distant metastasis occurred in 8 cases. Conclusion : The ratio of malignant tumor and metastasis was high. Therefore, when we faced with a tumor of the foot and ankle, the histopathologic confirmation is essential through biopsy before the definite initial treatment.

• Korean Journal of Applied Biomechanics
• /
• v.16 no.3
• /
• pp.105-115
• /
• 2006

The purpose of this study is to elucidate the mechanical characteristics of lower extremity joint movements at different walking speeds in obese people and suggest the very suitable exercise for obese person's own body weight and basic data for clinical application leading to medical treatment of obesity. This experimental subjects are all males between the ages of 20 and 30, who are classified into two groups according to Body Mass Index(BMI): one group is 15 people with normal body weight and the other 15 obese people. Walking speed is analysed at 3 different speeds ($1.5^m/s$, $1.8^m/s$, $2.1^m/s$) which is increased by $0.3^m/s$ from the standard speed of $1.5^m/s$. We calculated joint moments of lower extremity during stance phase through video recording and platform force measurement.Two-way ANOVA(Analysis of Variance, Mix) is applied to get the difference of moments according to walking speeds between normal and obese groups. Pearson's Correlation Analysis is applied to look into correlation between walking speeds and joint moments in both groups. Significance level of each experiment is set as ${\alpha}=.05$. As walking speed increases maximum ankle plantar flexion moment in the stance phase is smaller in obese group than in normal group, which is suggestive of weak toe push-off during terminal stance in obese group, and the highest maximum ankle plantar flexion moment in obese group during the middle speed walking($1.8^m/s.$). Maximum ankle dorsal flexion moment in obese group is relatively higher than in normal group and this is regarded as a kind of compensatory mechanism to decrease the impact on ankle when heel contacts the floor. Maximum knee flexion and extension moments are both higher in normal group with an increase tendency proportional to walking speed and maximum hip flexion and extension moments higher in obese group. In summary, maximum ankle plantar flexion moment between groups(p<.025), maximum knee moment not in flexion but in extension(p<.001) within each group according to increasing walking speed, and maximum hip flexion and extension moment(p<.001 and p<.004, respectively according to increasing walking speed are statistically significant but knee and hip moments between groups are not. Pearson correlation are different: high correlation coefficients in maximum knee flexion and extension moments, in maximum hip extension moment but not hip flexion, and in maximum ankle dorsal flexion moment but not ankle plantar flexion, in each group. We suspect that equilibrium imbalance develops when the subject increases walking speed and the time is around which he takes his foot off the floor.

• Archives of Reconstructive Microsurgery
• /
• v.4 no.1
• /
• pp.58-64
• /
• 1995

The radial forearm flap was first designed at the Ba-Ba Chung Hospital of People's Republic of China in 1978. The flap consists of the skin of the volar surface of the forearm, the subcutaneous fat, the underlying fascia, and the intramuscular fascia which includes the radial vessels. It is very useful flap in soft tissue coverage of skin defects of the upper and lower extremities. The authors have reported 13 cases of forearm free flap treated in the Korea University Hospital from January 1991 to Jun 1995 with a review of literature. The results were as follows. 1. We had good results in soft tissue coverage for all patients 2. The average size of flaps was $54cm^2$ and the average ischemic time of flaps was 74minutes. 3. The postoprative complication was occurred in three of 13 cases, two of three cases were arterial thrombosis treated with thrombectomy in postoperative 2 days, and one case was venous thrombosis resulted in superficial necrosis of the flap treated with STSG. 4. Forearm free flap with sensory innervation is a good donor site for reconstruction of weight-bearing areas of heel and sole. 5 The forearm free flap is suitable for soft tissue coverage of the upper and lower extremities, and can be used by skillful microsurgeon with high success rate.