CAJ | 학술논문

目的：比较骨质疏松尸体腰椎膨胀式椎弓根螺钉（expansive pedicle screw，EPS）固定与骨水泥强化椎弓根螺钉（polymethylmethacrylate-augmented pedicle screw，PMMA-PS）固定的稳定性。方法：16个腰椎标本取自4具新鲜尸体的脊柱（L1~L4）。年龄51~78岁，平均63岁，其中女性3具，男性1具。所有标本经X线检查排除畸形、骨折等病变，其中1个腰椎因严重畸形被剔除。测量各椎体的骨密度值（bone mineral density，BMD）后，将15个椎体随机分为3组。采用相同方法制备钉道，普通椎弓根螺钉（CPS）组直接置入CPS；PMMA-PS组先向钉道内注入PMMA，再置入CPS；EPS组直接置入EPS。置钉后24h，对标本进行X线检查和CT扫描，观察螺钉位置及骨水泥分布情况；然后将椎体固定于MTS 858上，沿椎弓根螺钉的长轴方向以10mm/min的加载速度进行拔出实验，测量螺钉的最大轴向拔出力（the maximum pullout strength，Fmax）和能量吸收值（energy absorbed value，EAV）。结果：所有腰椎的BMD均小于0.8g/cm2，T值为-3.5~-2.5，均为骨质疏松椎体，3组之间BMD 的差异无统计学意义（P>0.05）。 X 线检查和CT 重建显示各组螺钉位置均良好，PMMA-PS 组中未见PMMA渗漏现象；CPS组螺钉被周围的骨质直接包绕；PMMA-PS组螺钉被PMMA所包裹，PMMA存在于螺钉周围的骨质中，在椎体内形成了“纺锤样”结构；EPS组螺钉的前端在椎体内明显膨胀，形成了“爪状”结构。 CPS组、PMMA-PS 组和EPS 组的Fmax 分别为751.50±251.37N、1521.70±513.27N 和1175.20±396.51N，PMMA-PS组和EPS组均显著高于CPS 组（P<0.001，P=0.026），而PMMA-PS 组和EPS 组之间的差异无统计学意义（P=0.064）。 CPS 组、PMMA-PS 组和EPS 组的EAV 分别为1.47±0.51J、3.09±0.93J 和2.46±0.69J，PMMA-PS 组和EPS组均显著高于CPS组（P<0.001，P=0.005），而PMMA-PS组和EPS组之间的差异无统计学意义（P=0.067）。结论：EPS可显著提高骨质疏松腰椎内椎弓根螺钉的稳定性，达到了与传统PMMA强化椎弓根螺钉接近的固定强度，具有良好的临床应用前景。目的：比較骨質疏鬆尸體腰椎膨脹式椎弓根螺釘（expansive pedicle screw，EPS）固定與骨水泥彊化椎弓根螺釘（polymethylmethacrylate-augmented pedicle screw，PMMA-PS）固定的穩定性。方法：16箇腰椎標本取自4具新鮮尸體的脊柱（L1~L4）。年齡51~78歲，平均63歲，其中女性3具，男性1具。所有標本經X線檢查排除畸形、骨摺等病變，其中1箇腰椎因嚴重畸形被剔除。測量各椎體的骨密度值（bone mineral density，BMD）後，將15箇椎體隨機分為3組。採用相同方法製備釘道，普通椎弓根螺釘（CPS）組直接置入CPS；PMMA-PS組先嚮釘道內註入PMMA，再置入CPS；EPS組直接置入EPS。置釘後24h，對標本進行X線檢查和CT掃描，觀察螺釘位置及骨水泥分佈情況；然後將椎體固定于MTS 858上，沿椎弓根螺釘的長軸方嚮以10mm/min的加載速度進行拔齣實驗，測量螺釘的最大軸嚮拔齣力（the maximum pullout strength，Fmax）和能量吸收值（energy absorbed value，EAV）。結果：所有腰椎的BMD均小于0.8g/cm2，T值為-3.5~-2.5，均為骨質疏鬆椎體，3組之間BMD 的差異無統計學意義（P>0.05）。 X 線檢查和CT 重建顯示各組螺釘位置均良好，PMMA-PS 組中未見PMMA滲漏現象；CPS組螺釘被週圍的骨質直接包繞；PMMA-PS組螺釘被PMMA所包裹，PMMA存在于螺釘週圍的骨質中，在椎體內形成瞭“紡錘樣”結構；EPS組螺釘的前耑在椎體內明顯膨脹，形成瞭“爪狀”結構。 CPS組、PMMA-PS 組和EPS 組的Fmax 分彆為751.50±251.37N、1521.70±513.27N 和1175.20±396.51N，PMMA-PS組和EPS組均顯著高于CPS 組（P<0.001，P=0.026），而PMMA-PS 組和EPS 組之間的差異無統計學意義（P=0.064）。 CPS 組、PMMA-PS 組和EPS 組的EAV 分彆為1.47±0.51J、3.09±0.93J 和2.46±0.69J，PMMA-PS 組和EPS組均顯著高于CPS組（P<0.001，P=0.005），而PMMA-PS組和EPS組之間的差異無統計學意義（P=0.067）。結論：EPS可顯著提高骨質疏鬆腰椎內椎弓根螺釘的穩定性，達到瞭與傳統PMMA彊化椎弓根螺釘接近的固定彊度，具有良好的臨床應用前景。
목적：비교골질소송시체요추팽창식추궁근라정（expansive pedicle screw，EPS）고정여골수니강화추궁근라정（polymethylmethacrylate-augmented pedicle screw，PMMA-PS）고정적은정성。방법：16개요추표본취자4구신선시체적척주（L1~L4）。년령51~78세，평균63세，기중녀성3구，남성1구。소유표본경X선검사배제기형、골절등병변，기중1개요추인엄중기형피척제。측량각추체적골밀도치（bone mineral density，BMD）후，장15개추체수궤분위3조。채용상동방법제비정도，보통추궁근라정（CPS）조직접치입CPS；PMMA-PS조선향정도내주입PMMA，재치입CPS；EPS조직접치입EPS。치정후24h，대표본진행X선검사화CT소묘，관찰라정위치급골수니분포정황；연후장추체고정우MTS 858상，연추궁근라정적장축방향이10mm/min적가재속도진행발출실험，측량라정적최대축향발출력（the maximum pullout strength，Fmax）화능량흡수치（energy absorbed value，EAV）。결과：소유요추적BMD균소우0.8g/cm2，T치위-3.5~-2.5，균위골질소송추체，3조지간BMD 적차이무통계학의의（P>0.05）。 X 선검사화CT 중건현시각조라정위치균량호，PMMA-PS 조중미견PMMA삼루현상；CPS조라정피주위적골질직접포요；PMMA-PS조라정피PMMA소포과，PMMA존재우라정주위적골질중，재추체내형성료“방추양”결구；EPS조라정적전단재추체내명현팽창，형성료“조상”결구。 CPS조、PMMA-PS 조화EPS 조적Fmax 분별위751.50±251.37N、1521.70±513.27N 화1175.20±396.51N，PMMA-PS조화EPS조균현저고우CPS 조（P<0.001，P=0.026），이PMMA-PS 조화EPS 조지간적차이무통계학의의（P=0.064）。 CPS 조、PMMA-PS 조화EPS 조적EAV 분별위1.47±0.51J、3.09±0.93J 화2.46±0.69J，PMMA-PS 조화EPS조균현저고우CPS조（P<0.001，P=0.005），이PMMA-PS조화EPS조지간적차이무통계학의의（P=0.067）。결론：EPS가현저제고골질소송요추내추궁근라정적은정성，체도료여전통PMMA강화추궁근라정접근적고정강도，구유량호적림상응용전경。
Objectives: To compare the biomechanical characteristics of expansive pedicle screw (EPS) and polymethylmethacrylate-augmented pedicle screw(PMMA-PS) in osteoporotic cadaveric lumbar vertebrae. Meth-ods: A total of sixteen vertebrae (L1-L4) was obtained from four fresh-frozen human cadaveric spines with a mean of 63 years(range, 51 to 78 years). There were 3 females and 1 male specimens. Anterior-posterior and lateral radiographs of each vertebra were obtained to exclude vertebral fracture, deformity and osteolysis result-ing from malignancy. One markedly deformed vertebra was excluded from this study. After the measurement of bone mineral density(BMD) of all vertebral bodies, fifteen vertebrae were randomly divided into three groups. After the preparation of pilot hole by using the same method, the conventional pedicle screw(CPS) was inserted in CPS group, the pilot hole was filled with PMMA followed by CPS insertion in PMMA-PS group, and EPS was inserted in EPS group. Twenty four hours later, X-ray and CT scan were performed to exam the posi-tions of screws and distribution of PMMA. Then, all vertebrae were tightly fixed on MTS 858, each screw was pulled at a constant speed of 10mm/min until the failure of the pedicle screw, and the maximum pullout strength(Fmax) and energy absorbed value(EAV) were measured. Results: There was no significant difference in BMD among three groups (P>0.05). According to World Health Organization definition, vertebrae in three groups were osteoporotic with all BMD values less than 0.8g/cm2 and T values was between -3.5 and -2.5. No malposition of screw was detected in all groups and no cement leakage was detected in PMMA-PS group under X-ray and CT examination. In CPS group, screw was surrounded with bone tissue directly. In PMMA-PS group, screw was wrapped up by PMMA and PMMA existed in bone tissue around the CPS which shaped like a spindle-shaped structure in vertebral body. In EPS group, anterior part of EPS presented an obvious expansion in vertebral body and formed a clawlike structure. Fmax in CPS group, PMMA-PS group and EPS group was 751.50±251.37N, 1521.70±513.27N and 1175.20±396.51N, respectively. Fmax in PMMA-PS group and EPS group was significantly higher than that in CPS group (P<0.001, P=0.026). However, there was no significant difference in Fmax between PMMA-PS group and EPS group (P=0.064). EAV in CPS group, PMMA-PS group and EPS group was 1.47±0.51J, 3.09±0.93J and 2.46±0.69J, respectively. EAV in both PMMA-PS group and EPS group was significantly higher than that in CPS group(P<0.001, P=0.005). However, there was no significant difference in EAV between PMMA-PS group and EPS group(P=0.067). Conclusions:EPS can markedly enhance screw strength with a similar effect with traditional screw augmentation with PMMA for osteoporotic lumbar vertebrae.