• 비파괴검사학회지
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• 제35권2호
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• pp.103-111
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• 2015

본 연구에서는 골절 위험도가 높은 대퇴골의 두꺼운 피질골판이 해면질골의 초음파 특성에 미치는 영향을 조사하였다. 이를 위해 소의 대퇴골을 이용하여 12개의 해면질골을 제작하였으며, 피질골과 유사한 밀도 및 음속을 갖는 아크릴을 이용하여 피질골판을 모사하는 1.25, 1.80, 및 2.75 mm의 두께를 갖는 아크릴판을 제작하였다. 해면질골 양면에 부착된 아크릴판의 두께가 증가하더라도 음속과 해면질골의 겉보기 골밀도 사이에 Pearson 상관계수는 0.80-0.86의 값을 가지며, 높은 상관관계가 존재하는 것으로 나타났다. 또한 0.5 MHz에서 측정된 감쇠계수와 해면질골의 겉보기 골밀도 사이에 Pearson 상관계수는 0.84-0.91의 값을 가지며, 높은 상관관계가 존재하는 것으로 나타났다. 이와 같은 결과로부터 종골에 비해 상대적으로 더 두꺼운 피질골판을 갖는 대퇴골에서 측정된 음속 및 특정 주파수에서의 감쇠계수는 대퇴골의 골밀도를 예측하기 위한 지표로서 이용될 수 있음을 알 수 있다.

• Journal of Korean Neurosurgical Society
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• 제54권3호
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• pp.189-193
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• 2013

Objective : It remains debatable whether cervical spine fusion cages should be filled with any kind of bone or bone substitute. Cortical and subcortical bone from the anterior and posterior osteophytes of the segment could be used to fill the cage. The purposes of the present study are to evaluate the clinical outcomes and radiological outcomes including bone fusion and subsidence that occurred after anterior cervical discectomy and fusion using a stand-alone cage packed with local autobone graft. Methods : Thirty-one patients who underwent anterior cervical fusion using a stand-alone polyetheretherketone (PEEK) cage packed with local autobone graft from July 2009 to december 2011 were enrolled in this study. Bone fusion was assessed by cervical plain radiographs and computed tomographic scan. Nonunion was evaluated according to the absence of bony bridge on computed tomographic scan. Subsidence was defined as a ${\geq}2$ mm decrease of the interbody height at the final follow-up compared to that measured at the immediate postoperative period. Results : Subsidence was observed in 7 patients (22.6%). Of 7 patients with subsidence greater 2 mm, nonunion was developed in 3. Three patients with subsidence greater 2 mm were related with endplate damage during intraoperative endplate preparation. Solid bone fusion was achieved in 28 out of 31 patients (90.3%). Conclusion : With proper patient selection and careful endplate preparation, anterior cervical discectomy and fusion (ACDF) using a stand-alone PEEK cage packed with local autobone graft could be a good alternative to the standard ACDF techniques with plating.

• Journal of Korean Neurosurgical Society
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• 제52권5호
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• pp.435-440
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• 2012

Objective : The purpose of this study is to find the optimal stiffness and volume of bone cement and their biomechanical effects on the adjacent vertebrae to determine a better strategy for conducting vertebroplasty. Methods : A three-dimensional finite-element model of a functional spinal unit was developed using computed tomography scans of a normal motion segment, comprising the T11, T12 and L1 vertebrae. Volumes of bone cement, with appropriate mechanical properties, were inserted into the trabecular core of the T12 vertebra. Parametric studies were done by varying the volume and stiffness of the bone cement. Results : When the bone cement filling volume reached 30% of the volume of a vertebral body, the level of stiffness was restored to that of normal bone, and when higher bone cement exceeded 30% of the volume, the result was stiffness in excess of that of normal bone. When the bone cement volume was varied, local stress in the bony structures (cortical shell, trabecular bone and endplate) of each vertebra monotonically increased. Low-modulus bone cement has the effect of reducing strain in the augmented body, but only in cases of relatively high volumes of bone cement (>50%). Furthermore, varying the stiffness of bone cement has a negligible effect on the stress distribution of vertebral bodies. Conclusion : The volume of cement was considered to be the most important determinant in endplate fracture. Changing the stiffness of bone cement has a negligible effect on the stress distribution of vertebral bodies.

• 대한의용생체공학회:의공학회지
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• 제37권2호
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• pp.90-103
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• 2016

본 연구는 유한 요소 법을 이용한 노화되어 강성/강도가 저하되는 요추 체의 얇은 피질과 해면 골의 하중 분담 비율 분석과 사용된 탄성계수들의 평가가 목적이다. 해면 골의 나은 해석을 위하여, 20년마다 압축 시험에서 얻은 탄성계수를 체적 공극 비율로 나눈 유효 탄성계수를 사용하였다. 이와 상응하는 피질 쉘도 공극 비율을 포함한 빔 이론의 수식들로부터 유효 탄성계수를 구한 후에 적용하였다. 또한 p-요소를 사용하여 수치 오차를 최소화하였다. 보고된 논문들을 참고하여 후관절 부분이 제거된 매개 변수적인 퇴행된 L3 척추 형상을 만들어 유한 요소 모델링 하였다. 일정 변위의 압축 조건을 가한 후에 여덟 조각의 부피 별로 각 뼈에서 탄성 변형률 에너지와 수직 하중의 비율을 사용하여 하중 분담 비율을 계산하였다. 결과로는 1) 20대에서 80대까지 해면 골의 하중 비율은 55%에서 49%로 감소하였다; 2) 피질 쉘은 중간 면에서 최고 비율을, 해면 골은 종판에서 최고 비율을 나타냈다; 3) 다공성 얇은 피질과 해면 골을 위한 유효 탄성계수의 사용은 적절하였다; 4) 두 방법을 이용하여 얻은 하중 분담 비율의 차이는, 전체 비율은 1% 미만 내에서 같지만 각 위치에서의 비율 값들은 약간 달랐다.

• Journal of Korean Neurosurgical Society
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• 제30권7호
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• pp.907-915
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• 2001

Objective : Percutaneous vertebroplasty is often complicated by the presence of multiple fractures or non-localizing pain in the patients with osteoporotic vertebral fractures. The purpose of this study is to estimate the value of preoperative radiologic studies in the localization of symptomatic vertebrae and to determine the factors which can influence on the clinical results. Materials and Methods : We retrospectively reviewed the clinical and radiologic data of 57 vertebrae in 30 patients underwent percutaneous vertebroplasty for osteoporotic vertebral compression fractures. Inclusion criteria was severe pain(McGill-Melzack score 3, 4 or 5) associated with the acute vertebral fractures and absence of spinal nerve root or cord compression sign. Acute symptomatic vertebral fracture was determined by the presence of signal change on MR images or increased uptake on whole body bone scan. Results : Pain improvement was obtained immediately in all patients and favorable result was sustained in 26 patients(86.7%) during the mean follow-up duration of 4.7 months(5 complete pain relief, 21 marked pain relief). Those who underwent vertebroplasty for all acute symptomatic vertebrae had significantly better clinical result than those who did not. Further vertebral collapse and eventual bursting fracture occurred in 1 vertebra which showed intradiskal leakage of bone cement and disruption of cortical endplate on postoperative CT scan. Conclusion : Preoperative MR imaging and whole body bone scan are very useful in determining the symptomatic vertebrae, especially in the patients with multiple osteoporotic vertebral fractures. To obtain favorable clinical result, the careful radiologic evaluation as well as clinical assessment is required. Control of PMMA volume seems to be the most critical point for avoiding complications.