• Journal of the Korean Arthroscopy Society
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• v.5 no.2
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• pp.69-73
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• 2001

Purpose : To evaluate the clinical results and widening of bony tunnel after anterior cruciate ligament(ACL) reconstruction using hamstring tendon with Ligament Anchor(LA) screw, which is newly designed fur fixation of graft into femur. Materials and Methods : Fifty eight patients who were followed up at least more than 2 years after ACL reconstruction with four strands of Hamstring tendon were included in this study. The graft was fixed with LA screw at femoral tunnel and with bioabsorbable interference screw at tibial tunnel. The average period of follow-up was 28 months. The clinical results such as physical examination and Lysholm knee score and radiological results. widening of bony tunnel and instrumented anterior laxity test with $Telos^{\circledR}$(Telos stress device; Austin & Associates, Inc., Polston, US) were evaluated. Results . The Lysholm knee score was 60.0 in average preoperatively and improved to 94.0 in average at follow up. On the Lachman test, there were mild(+) instability in 16 cases, moderate(++) in 24, severe(+++) in 18 preoperatively. 50 cases were converted to negative and 8 to mild instability at follow up. On instrumented anterior laxity test with $Telos^{\circledR}$, side to side difference in 20 lb was 12.9mm in average preoperatively, and was decreased to 3.1mm in average follow-up. The femoral tunnel was widened from 10.6mm postoperatively to 12.7mm$(21.1\%)$ at follow up on antero-posterior plane and from 10.7mm to 12.4mm$(16.5\%)$ on lateral plane. Tibial tunnels was also widened from 9.8mm to 11.8mm$(20.7\%)$ on antero-posterior plane and from 9.9mm to 11.7mm$(18.9\%)$ in lateral plane. Conclusion : ACL reconstruction with hamstring tendon and LA screw was one of the choice of grafts and fixatives in restoring knee stability and in improving clinical results with little complications such as excessive widening of bony tunnel.

• 대한관절경학회:학술대회논문집
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• 2006.11a
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• pp.96-97
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• 2006

• Journal of the Korean Arthroscopy Society
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• v.7 no.2
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• pp.189-195
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• 2003

Purpose : To evaluate the clinical results after anterior cruciate ligament (ACL) reconstruction with hamstring tendon and Ligament Anchor (LA) screw Materials and Methods : 103 patients (104 cases) who were followed up at least more than 2 years after ACL reconstruction were included in this study. The average period of follow-up was 36 months. The clinical results such as physical examination and Lysholm knee score and instrumented anterior laxity test with Telos were evaluated. Results : The Lysholm knee score was 57.9 in average preoeratively and improved to 95.2 in average at follow up. On the Lachman test, there were mild (+) instability in 46 cases $(45\%)$, moderate (++) in 33 $(31\%)$, severe (+++) in 25 $(24\%)$ preoperatively. 90 cases $(87\%)$ were converted to negative and 14 $(13\%)$ to mild at follow up. On Pivot-shift test, there were negative (-) instability in 22 cases $(22\%)$, mild (+) in 62 $(59\%)$, moderate (++) in 12 $(11\%)$ and severe in 8 $(8\%)$ preoperatively. 87 cases $(84\%)$ were converted to negative and 17 $(16\%)$ to mild at follow up. On instrumented anterior laxity test with $Telos^{\circledR}$, side to side difference on 20 lb was $13.4{\pm}5.6$ (7-25) mm in average preoperatively, and was decreased to $3.6{\pm}1.5$ (1-6) mm in average at follow-up. Complications were quadriceps muscle atrophy in 27 $(30.0\%)$, saphenous nerve paresthesia in 19 $(18.3\%)$, anterior knee crepitus in 13 $(12.5\%)$ and over-penetration of screw through lateral femoral cortex in 5 cases $(4.8\%)$. Conclusion : ACL reconstruction with hamstring tendon and LA screw was one of the choice of graft and fixatives in restoring knee stability and in improving clinical results with little complications such as anterior knee pain.

• Journal of Korean Orthopaedic Sports Medicine
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• v.1 no.1
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• pp.21-25
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• 2002

Purpose: To evaluate the clinical results after anterior cruciate ligament (ACL) reconstruction with hamstring tendon and Ligament Anchor (LA) screw, which is newly designed for fixation of graft into femur. Materials and Methods: Fifty eight patients who were followed up at least more than 2 years after ACL reconstruction with four strands of Hamstring tendon and LA screw were included in this study. The graft was fixed with LA screw at femoral tunnel and with only bioabsorbable interference screw at tibial tunnel. The mean follow-up period was 28 months. The clinical results were evaluated by physical examination and Lysholm knee score. Widening of bony tunnel and anterior laxity difference compared with normal side by instrumented anterior laxity test with Telos(R) (Telos stress device; Austin & Associates, Inc., Polston, US) were evaluated. Results: The Lysholm knee score improved from 60.0 points preoperatively to 94.0 points at last follow up. On the Lachman test, there were mild (+) instability in 16 cases, moderate (++) in 24,severe (+++) in 18 preoperatively. 50 cases were converted to negative and 8 to mild instability at postoperative follow up. On instrumented anterior laxity test with Telos(R), difference between normal and affected knee on 20 lb was 12.9 mm in average preoperatively, and was decreased to 3.1mm at last follow-up. The femoral tunnel was widened from 10.6 mm postoperatively to 12.7 mm (21.1$\%$) at follow up on antero-posterior plane and from 10.7 mm to 12.4 mm (16.5$\%$) on lateral plane. Tibial tunnels was also widened from 9.8mm to 11.8mm (20.7$\%$) on antero-posterior plane and from 9.9mm to 11.7 mm ($18.9\%$) on lateral plane. Complications were: anterior knee crepitus in 17 case, quadriceps muscle atrophy(>3 cm) in 6, penetration of screw over the lateral femoral cortex in 5, saphenous nerve paresthesia in 2.Conclusions: ACL reconstruction with hamstring tendon and LA screw was one of the choice of grafts and fixation devices in restoring knee stability and in improving clinical results with little complications such as excessive widening of bony tunnel and anterior knee pain

• Journal of Korean Neurosurgical Society
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• v.63 no.6
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• pp.777-783
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• 2020

Objective : To compare the accuracy and breach rates of freehand (FH) versus navigated (NV) pedicle screws in the thoracic and lumbar spine in patients with metastatic spinal tumors. Methods : A retrospective review of adult patients who underwent pedicle screw fixation in the thoracic or lumbar spine for metastatic spinal tumors between 2012 and 2018 was conducted. Breaches were assessed based on the Gertzbein and Robbins classification and only screws placed >4 mm outside of the pedicle wall (lateral or medial) were considered breached. Results : A total of 62 patients received 547 pedicle screws (average 8 per patient) - 34 patients received 298 pedicle screws in the FH group and 28 patients received 249 screws in the NV group. There were 40/547 breaches, corresponding to a breach and accuracy rate of 7.3% and 92.7%, respectively. The breach rate was 9.7% in the FH group and 4.4% in the NV group (chi-squared test, p=0.017); this corresponded to an accuracy rate of 90.3% and 95.6%, respectively. Only one patient from the overall cohort (in the FH group) required revision surgery due to a medial breach abutting the spinal cord (1.6% of all patients; 2.9% of FH patients); no patient suffered organ, vessel, or neurological injury from screw breaches. Conclusion : Navigated pedicle screw placement in patients with metastatic spinal tumors has a significantly higher radiographic accuracy compared to the FH technique. However, the revision surgery was low and no patient suffered from clinically-relevant breach. Navigation also offers the advantage of real-time localization of spinal tumors and aids in targeting and resection of these lesions.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.43 no.2
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• pp.77-82
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• 2017

Objectives: The aim of this study was to compare the mechanical resistance of four different osteosyntheses modeled in two different sagittal split ramus osteotomy (SSRO) designs and to determine the linear loading in a universal testing machine. Materials and Methods: An in vitro experiment was conducted with 40 polyurethane hemimandibles. The samples were divided into two groups based on osteotomy design; Group I, right angles between osteotomies and Group II, no right angles between osteotomies. In each group, the hemimandibles were distributed into four subgroups according to the osteosynthesis method, using one 4-hole 2.0 mm conventional or locking plate, with or without one bicortical screw with a length of 12.0 mm (hybrid technique). Each subgroup contained five samples and was subjected to a linear loading test in a universal testing machine. Results: The peak load and peak displacement were compared for statistical significance using PASW Statistics 18.0 (IBM Co., USA). In general, there was no difference between the peak load and peak displacement related to osteotomy design. However, when the subgroups were compared, the osteotomy without right angles offered higher mechanical resistance when one conventional or locking 2.0 mm plate was used. One locking plate with one bicortical screw showed higher mechanical resistance ($162.72{\pm}42.55N$), and these results were statistically significantly compared to one conventional plate with monocortical screws (P=0.016) and one locking plate with monocortical screws (P=0.012). The difference in peak displacement was not statistically significant based on osteotomy design or internal fixation system configuration. Conclusion: The placement of one bicortical screw in the distal region promoted better stabilization of SSRO. The osteotomy design did not influence the mechanical behavior of SSRO when the hybrid technique was applied.

• Journal of Korean Orthopaedic Sports Medicine
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• v.2 no.1
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• pp.28-36
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• 2003

Purpose: To determine and to compare the effects of cyclic loading on the fixation strength of different femoral fixation methods in ACL reconstruction. Materials and Methods: Biomechanical test using an Instron(R) machine (Model No.5569. Mass, U.S.A) were carried out to compare the pull out strength of six different femoral fixation techniques after a cyclic loading in 72 Yorkshire pig knees. The graft-bone complex was cyclically loaded between 30N and 150N at 50 mm/min rate for 1000 cycles and maximal tensile testing was performed. A preload of 30N was applied to the graft along the axis of the tunnel 15 minutes. ANOVA and the Duncan multiple comparison test was used for the statistical analysis. Results: The mean maximum tensile strength of femoral fixation before and after the cyclic loading test were 1003.4$\pm$145N and 601.1$\pm$154N in hamstring-LA screw(R) group, 595.5$\pm$104N and 360.7$\pm$56N in hamstring-Bioscrew(R) group, 1431.7$\pm$135N and 710.7$\pm$114N in hamstring-Semifix(R) group, 603.6$\pm$54N and 459.1$\pm$46N in hamstring-Endobutton(R) fixation group, 1067.4$\pm$145 and 601.8$\pm$134N in the BPTB-Titanium interference screw group, and 987.1$\pm$168N and 588.7$\pm$124N in the BPTB-Bioscrew(R) group. And these data illustrated that cyclic loading reduces the maximum tensile strength by 40 $\%$, 39 $\%$, 50 $\%$, 24 $\%$, 44 $\%$, 40 $\%$ respectively. Conclusions: With the results of these experiments it should be emphasized that rehabilitation exercises after anterior cruciate ligament reconstruction should be executed with precaution as the repetitive flexion and extension of the knee would compromise the maximum tensile strength of the graft tendon.

• Journal of the Korean Arthroscopy Society
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• v.10 no.2
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• pp.141-147
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• 2006

Purpose: To compare the clinical and radiological results of anterior cruciate ligament(ACL) reconstruction using hamstring autograft and tibialis tendon allograft. Materials and Methods: Twenty four ACL reconstructions using hamstring autograft and 30 using tibialis anterior tendon altograft were followed up at least 1 year. We performed femoral tunnel fixation with Ligament Anchor(LA) screw and tibial tunnel fixation with biodegradable interference screw. Evaluations included Lysholm knee(LK) score, Tegner activity scale, Lachman test, Pivot-Shift test, Quardriceps atrophy, incision site numbness, anterior knee pain and instrumented anterior laxity with $Telos^{(R)}$ device. Results: Preoperativ mean LK score was $60.3(18{\sim}82)$ in autograft group and 61.2(25-80) in allograft group. Mean LK score improved to $91.6(68{\sim}100)\;and\;92.6(77{\sim}100)$ respectively. Activity level, using Tegner activity scale, slightly decreased compared with that of Preinjury state in both groups. Lachman test, pivot-shift test, Quadriceps atrophy, anterior knee pain, incision site numbness, and anterior drawer test using $Telos^{(R)}$ device showed no significant difference between two groups (p>0.05). Conclusion: In performing the ACL reconstruction, there was no statistically significant difference between hamstring autograft group and tibilis anterior allograft group in clinical or in radiological results.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.41 no.3
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• pp.133-138
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• 2015

Objectives: To evaluate the influence of the type of osteotomy in the inferior aspect of the mandible on the mechanical performance. Materials and Methods: The study was performed on 20 polyurethane hemimandibles. A sagittal split ramus osteotomy (SSRO) was designed in 10 hemimandibles (group 1) with a vertical osteotomy in the buccal side (second molar level) and final osteotomy was performed horizontally on the lingual aspect, while the mandible body osteotomy was finalized as a straight osteotomy in the basilar area, perpendicular to the body. For group 2, the same osteotomy technique was used, but an oblique osteotomy was done in the basilar aspect of the mandibular body, forming continuity with the sagittal cut in the basilar area. Using a surgical guide, osteosynthesis was performed with bicortical screws using an inverted L scheme. In both groups vertical compression tests were performed with a linear load of 1 mm/min on the central fossa of the first molar and tests were done with models made from photoelastic resin. Data were analyzed using Student's t-test, establishing a statistical significance when P<0.05. Results: A statistical difference was not observed in the maximum displacements obtained in the two osteotomies (P<0.05). In the extensiometric analysis, statistically significant differences were identified only in the middle screw of the fixation. The photoelastic resin models showed force dissipation towards the inferior aspect of the mandible in both SSRO models. Conclusion: We found that osteotomy of the inferior aspect did not influence the mechanical performance for osteosynthesis with an inverted L system.

• Journal of Korean Neurosurgical Society
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• v.30 no.10
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• pp.1210-1219
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• 2001

Introduction : The purpose of this study was to analyze the safety, pullout strength and radiographic characteristics of unicortical and bicortical screws of cervical facet within cadaveric specimens and evaluate the influence of level of training on the positioning of these screws. Methods : Twenty-one cadavers, mean 78.9 years of age, underwent bilateral placement of 3.5mm AO lateral mass screw from C3-C6(n=168) using a slight variation of the Magerl technique. Intraoperative imaging was not used. The right side(unicortical) utilized only 14mm screws(effective length of 11mm) while on the left side to determine the length of the screw after the ventral cortex had been drilled. Three spine surgeons(attending, fellow, chief resident) with varying levels of spine training performed the procedure on seven cadavers each. All spines were harvested and lateral radiographs were taken. Individual cervical vertebrae were carefully dissected and then axial radiographs were taken. The screws were evaluated clinically and radiographically for their safety. Screws were graded clinically for their safety with respect to the spinal cord, facet joint, nerve root and vertebral artery. The grades consisted of the following categories : "satisfactory", "at risk" and "direct injury". Each screw was also graded according to its zone placement. Screw position was quantified by measuring a sagittal angle from the lateral radiograph and an axial angle from the axial radiograph. Pull-out force was determined for all screws using a material testing machine. Results : Dissection revealed that fifteen screws on the left side actually had only unicortical and not bicortical purchase as intended. The majority of screws(92.8%) were satisfactory in terms of safety. There were no injuries to the spinal cord. On the right side(unicortical), 98.9% of the screws were "satisfactory" and on the left side(bicortical) 68.1% were "satisfactory". There was a 5.8% incidence of direct arterial injury and a 17.4% incidence of direct nerve root injury with the bicortical screws. There were no "direct injuries" with the unicortical screws for the nerve root or vertebral artery. The unicortical screws had a 21.4% incidence of direct injury of the facet joint, while the bicortical screws had a 21.7% incidence. The majority of "direct injury" of bicortical screws were placed by the surgeon with the least experience. The performance of the resident surgeon was significantly different from the attending or fellow(p<0.05) in terms of safety of the nerve root and vertebral artery. The attending's performance was significantly better than the resident or fellow(p<0.05) in terms of safety of the facet joint. There was no relationship between the safety of a screw and its zone placement. The axial deviation angle measured $23.5{\pm}6.6$ degrees and $19.8{\pm}7.9$ degrees for the unicortical and bicortical screws, respectively. The resident surgeon had a significantly lower angle than the attending or fellow(p<0.05). The sagittal angle measured $66.3{\pm}7.0$ degrees and $62.3{\pm}7.9$ degrees for the unicortical and bicortical screws, respectively. The attending had a significantly lower sagittal angle than the fellow or resident(p<0.05). Thirty-three screws that entered the facet joint were tested for pull-out strength but excluded from the data because they were not lateral mass screws per-se and had deviated substantially from the intended final trajectory. The mean pull-out force for all screws was $542.9{\pm}296.6N$. There was no statistically significant difference between the pull-out force for unicortical($519.9{\pm}286.9N$) and bicortical($565.2{\pm}306N$) screws. There was no significant difference in pull-out strengths with respect to zone placement. Conclusion : It is our belief that the risk associated with bicortical purchase mandates formal spine training if it is to be done safely and accurately. Unicortical screws are safer regardless of level of training. It is apparent that 14mm lateral mass screws placed in a supero-lateral trajectory in the adult cervical spine provide an equivalent strength with a much lower risk of injury than the longer bicortical screws placed in a similar orientation.