迦瑪骨釘(Gamma nail)和滑動式螺絲骨板(sliding screw plate)已廣泛的應用於治療股骨近心端骨折，從臨床觀察中發現，在骨折治療過程中植入物會發生的失效模式有破壞和鬆脫等情形，在股骨頭部分，常因為植入物的影響而發生骨切效應(cut out)的情形，而若發生股骨轉子下骨折時，植入物的穩定性就尤其重要。本文主要是利用有限元素法分析兩種市售的骨科植入物(迦瑪骨釘和滑動式螺絲骨板)與自行研發的雙螺絲骨釘(Double Screw Nail)來進行其三種股骨植入物之優劣性分析及討論，並使用生物力學測試方法來進行驗證。
有限元素法方面，利用斷層掃瞄(CT Scan)掃瞄出股骨的三維立體輪廓剖面，並轉入有限元素軟體ANSYS中建立三維實體股骨。在股骨頭上施加髖關節反力與在大轉子上施加肌肉力，並將遠端股骨底部進行完全的拘束。本文考慮三種骨折情形：股骨頸骨折、股骨轉子下骨折和股骨轉子下有間隙骨折，並取得有限元素分析數值之von Mises應力、位移、總應變能和應變能密度。在生物力學測試方面，分別建立三種近端股骨骨折，並將三種骨科植入物分別植入人造假骨內，負荷條件與邊界條件與有限元素法之實體模型相同。實驗之後處理方面，將會取得實驗之負荷與位移，並計算出彎曲勁度，而生物力學測試的結果將會與有限元素分析之數值作相關性比較。
在有限元素模擬的結果中可以發現，應變能密度比von Mises應力有更好的預測結果，並且在有限元素分析與生物力學測試的比較是有很好的相關性(>0.72)。雙螺絲骨釘不僅能夠減少迦瑪骨釘在股骨幹的應力集中，且沒有像滑動式螺絲骨板有相當高的骨切效應。根據本研究中的有限元素分析之模型，能夠反映出臨床上的觀察。本研究能提供工程界人士設計新型骨科植入物，並能幫助醫師為病人選擇適合之植入物。

The gamma nail and sliding screw plate have been popularly used to the treatment of proximal femoral fracture. In the clinical point of view, the implants may be failed and cause loss of fracture fixation in impairment of fracture healing. In addition, the femoral head may be cut out by those implants especially for the patients with osteoporosis. In this study, two types of commercial available implants (gamma nail and sliding screw plate) and a newly designed implant (double screw nail) were assessed by finite element analyses and biomechanical tests. The purposes of this study were to evaluate the mechanical performances of these fracture fixators and to verify the rationality of finite element analyses by using biomechanical tests.
In finite element analysis, in accordance with the bone structures and geometry gained from a computed tomography (CT) scan, the anatomical shape for femur was created. Then the CT scan models were transformed into three-dimensional solid models by image processing and Boolean operation. A joint reaction force which was applied at the center of femoral head and an abductor muscle force which was applied at the greater trochanter were used and the end of distal femur was fully constrained. Three kinds of fractures were discussed including femoral neck fracture, subtrochanter fracture, and subtrochanteric fracture with gap. The von Mises stress, displacement, total strain energy, and strain energy density were obtained. In biomechanical tests, three kinds of proximal femoral fracture were created and three kinds of implants were implanted into the artificial femur. The loading and boundary conditions were similar to the finite element models. The load and displacement were measured and the stiffness was calculated. The results of biomechanical tests were compared with the results of finite element analyses.
From the results of finite element simulation, the strain energy density is a good predictor as compared with the von Mises stress in this study. The results of finite element analyses were closely related to those of biomechanical tests with high correlation coefficient (>0.72). The double screw nail can eliminate the stress concentration at the femoral shaft as compared with the gamma nail and decrease the risk of bone cut out as compared with sliding screw plate. Developing the finite element models in this study could be used to reflect the clinical observation. This study could assist the engineers to design new orthopedics implants and help the surgeons to select suitable implants for their patients.

[1]楊榮森，臨床骨折學，第268頁，台北，合記圖書出版社，民國七十八年。
[2]Wang, C.J., C.J. Brown, A.L. Yettram, and P. Procter, “Intramedullary Femoral Nails: One or Two Lag Screws? A Preliminary Study,” Medical Engineering & Physics, Vol.22, pp.613-624(2000).
[3]Brown, C.J., C.J. Wang, A.L. Yettram, and P. Procter, “Intramedullary Nails with Two Lag Screws,” Clinical Biomechanics, Vol.19, pp.519-525(2004).
[4]Halder, S.C., “The Gamma Nail for Peritrochanteric Fractures,” J Bone Joint Surg, Vol.74B, pp.340-344(1992).
[5]陳育斌，股骨鎖定內釘之有限元素分析與生物力學測試，台灣科技大學機械工程系碩士論文，民國90年(2001)。
[6]林 晉，鎖定式骨髓內釘之基礎科學與臨床應用，第135-149頁，台北，合記圖書出版社，民國93年(2004)。
[7]Haynes, R.C., R.G. Poll, A.W. Miles, and R.B. Weston, “An Experimental Study of the Failure Modes of the Gamma Locking Nail and AO Dynamic Hip Screw Under Static Loading: A Cadaveric Study,” Medical Engineering & Physics, Vol.19, pp.446-453(1997).
[8]Bridle, S.H., A.D. Patel, M. Bircher, and P.T. Calvert, “Fixation of Intertrochanteric Fractures of the Femur,” J Bone Joint Surg, Vol.73B, No.2, pp.330-334(1991).
[9]Deith L. Moore and Arthur F. Dalley，ANATOMY，Hagerstown，Lippincott Williams & Wilkins，2001.
[10]Radford, P.J., M. Needoff, and J.K. Webb, “A Prospective Randomised Comparison of the Dynamic Hip Screw and the Gamma Locking Nail,” J Bone Joint Surg, Vol.75B, No.5, pp.789-793(1993).
[11]Rosenblum, S.F., J.D. Zuckerman, F.J. Kummer, and B.S. Tam, “A Biomechanical Evaluation of the Gamma Nail,” J Bone Joint Surg, Vol.74B, pp.352-357(1992).
[12]Ingman, A.M., “Percutaneous Intramedullary Fixation of Trochanteric Fractures of the Femur Clinical Trial of A New Hip Nail,” Injury, Int. J. Care Injured, Vol.31, pp.483-487(2000).
[13]Sitthiseripratip, K., H.V. Oosterwyck, J.V. Sloten, B. Mahaisavariya, E.L.J. Bohez, J. Suwanprateeb, R.V. Audekercke, and P. Oris, “Finite Element Study of Trochanteric Gamma Nail for Trochanteric Fractrue,” Medical Engineering & Physics, Vol.25, pp.99-106(2003).
[14]Apel, D.M., A. Patwardhsn, M.S. Pinzur, and W.R. Dobozi, “Axial Loaning Studies of Unstable Intertrochanteric Fractures of the Femur,” Clinical Orthopaedics and Related Research, Vol.246, pp.156-164(1989).
[15]Mahomed, N., I. Harrington, J. Kellam, G. Maistrelli, T. Hearn, and J. Vroemen, “Biomechanical Analysis of the Gamma Nail and Sliding Hip Screw,” Clinical Orthopaedics and Related Research, No.304, pp.280-288(1994).
[16]Leung, K.S., W.S. So, W.Y. Shen, and P.W. Hui, “Gamma Nails and Dynamic Hip Screws for Peritorchanteric Fractures,” J Bone Joint Surg, Vol.74B, No.3, pp.345-351(1992).
[17]Gaebler, C., S. stanzl-Tschegg, E.K. Tschegg, C. Kukla, W.A. Menth-Chiari, G.E. wozasek, and T. Heinz, “Implant Failure of the Gamma Nail,” Injury, Int. J. Care Injured, Vol.30, pp.91-99(1999).
[18]Ovadia, D.N.J.L. Chess, “Intraoperative and Postoperative Subtrochanteric Fracture of the Femur Associated with Removal of the Zickel Nail,” J Bone Joint Surg, Vol.70A, No.2, pp.239-243(1988).
[19]陳新郁、林政仁，有限元素分析 – 理論與應用 ANSYS，第5~7頁，台北，高立圖書有限公司，民國90年(2001)。
[20]Wang, C.J., A.L. Yettram, M.S. Yao, and P. Procter, “Finite Element Analysis of A Gamma Nail within A Fractured Femur,” Medical Engineering, Vol.20, pp.677-683(1998).
[21]Hayes, W.C., E.R. Myers, J.N. Morris, T.N. Gerhart, H.S. Yett, and L.A. Lipsitz, “Impact Near the Hip Dominates Fracture Risk in Elderly Nursing Home Residents who Fall,” Calcif Tissue Int, Vol.52, No.3, pp.192-198(1993).
[22]Brink, W.A.I.M.C. Janssen, “Failure of the Gamma Nail in A Highly Unstable Proximal Femur Fracture: Report of Four Cases Encountered in the Netherlands,” Journal of Orthopaedic Tuauma, Vol.9, No.1, pp.53-56(1995).
[23]Seif-Asaad, S.S., A.V.F. Nargol, and A. Port, “Unstable Intertrochanteric Fracture Treated with the Variwall Reconstruction Nail, Injury,” Vol.26, No.6, pp.367-372(1995).
[24]Garnavos, C., A. Peterman, and P.W. Howard, “The Treatment of Difficult Proximal Femoral Fractures with the Russell-Taylor Reconstruction Nail,” Injury, Int. J. Care Injured, Vol.30, pp.407-415(1999).
[25]Roberts, C.S., A. Nawab, M. Wang, M.J. Voor, and D. Seligson, “Second Generation Intramedullary Nailing of Subtrochanteric Femur Fractures: A Biomechanical Study of Fracture Site Motion,” Journal of Orthopaedic Tuauma, Vol.16, pp.231-238(2002).
[26]Kubiak, E.N., M. Bong, S.S. Park, F. Kummer, K. Egol, and K.J. Koval, “Intramedullary Fixation of Unstable Intertrochanteric Hip Fracture One or Tow Lag Screws,” J Orthop Trauma, Vol.18, pp.12-17(2004).
[27]Seral, B., J.M. Garcia, J. Cegonino, M. Doblare, and F. Seral, “Finite Element Study of Intramedullary Osteosynthesis in the Treatment of Trochanteric Fractures of the Hip: Gamma and PFN,” Injury, Int. J. Care Injured, Vol.35, pp.130-135(2004).
[28]Chen, W.P., C.L. Tai, C.H. Shih, P.H. Hhseh, M.C. Leou, and M.S. Lee, “Selection of Fixation Devices in Proximal Femur Rotational Osteotomy: Clinical Complications and Finite Element Anslysis,” Clinical Biomechanics, Vol.19, pp.255-262(2004).
[29]Fritz, T., D. Hiersemann, C. Krieglstein, and W. Friedl, “Prospective Randomized Comparison of Gliding Nail and Gamma Nail in the Therapy of Trochanteric Fractures,” Arch Orthop Trauma Surg, Vol.119, pp.1-6(1999).
[30]Ashby, M.E.J.C. Anderson, “Treatment of Fractures of the Hip and Ipsilateral Femur with the Zickel Device,” Clinical Orthopaedics and Related Research, pp.156-160(1977).
[31]余志成，機械系統設計，第60~90頁，台北，高立圖書有限公司，民國91年(2002)。
[32]梁蘭麗，股骨Z型外翻截骨術之三維有限元素分析，中原大學醫學工程系碩士論文，民國92年(2003)。
[33]孫施盛，退化性關節炎與骨質疏鬆性股骨頭之生物力學性質分析，陽明大學醫學工程系碩士論文，民國91年(2002)。
[34]陳博光，現代骨科診療室，第213~221頁，台北，正中書局，民國89年(2000)。
[35]周建基，股骨近心端治療之有限元素分析，國立台灣科技大學機械工程系碩士論文，民國93年(2004)。
[36]呂元喬，逆行性骨髓內釘之生物力學分析，國立成功大學醫學工程所碩士論文，民國92年(2003)。
[37]Plausinis, D, C. Greaves, W.D. Regan, T.R. Oxland, “Ipsilateral shoulder and elbow replacements: On the risk of periprosthetic fracture.” Clinical Biomechanics, Vol.20, pp.1055-1063(2005).