PFN与DCS治疗股骨转子下骨折的生物力学研究

A Biomechanical Study of PFN and DCS in Treatment of Subtrochanteric Fractures of Femur

目的比较PFN和DCS固定股骨转子下骨折的生物力学性能。方法成年男性新鲜尸体股骨6对,每对标本随机分成PFN和DCS固定组,先后模拟SeinsheimerⅠ型骨折、ⅢA型骨折恢复内侧皮质完整、ⅢA型骨折移除内侧皮质。在生物力学实验机上予垂直载荷,测定抗压载荷及股骨近端应变分布情况。结果PFN对股骨的正常生理应力分布的干扰较DCS明显。两组刚度差异不明显,仅在ⅢA型骨折移除内侧皮质标本PFN的刚度明显高于DCS(P<0.05)。两者均能提供较强的极限载荷,PFN组高于DCS组(P<0.05)。结论对于SeinsheimerⅠ型骨折,PFN与DCS均可作为较好的内固定物选择。在ⅢA型骨折,PFN生物力学特性要明显优于DCS,尤其是内侧皮质复位不佳者。术后功能锻炼时,两者均要采取保护性的功能锻炼方法。

Objective To compare the biomechanical characteristics of the proximal femoral nail （PFN） and the dynamic condylar screw （DCS） in the treatment of the subtroehanterie fractures of the femur. Methods Six matched pairs of fresh eadaverie femur specimens were divided into two groups. Each pair of femur was randomized to a test group. After PFN and DCS were implanted respectively, Seinsheimer type Ⅰ, type ⅢA （ to restore the medial cortices）, type ⅢA （to remove the medial cortices） subtrochanterie fracture models were sequentially produced. The increasing stress was loaded on these fixed femurs to compare their press properties and the strain distribution of proximal femurs. Results The PFN significant inteiered with the normal load distribution pattern in the intact femur more significantly than the DCS. But it was important to restore medial buttress for the DCS. There was no significant difference in the stiffhess of PFN and DCS. But in type ⅢA （to remove the medial cortices） subtroehanterie fracture, the PFN implant had the greater stiffness than DCS. The PFN withstood significantly higher loads to failure than the DCS. Conclusion The PFN and DCS are recommended for type Ⅰ fracture. The PFN is good choice for the fixation of type ⅢA fracture and the better choice for type ⅢA fracture （to remove the medial cortices）. It is essential for the two types of implants to take protective postoperative exercises.