INTRODUÇÃO: As osteotomias são formas reconhecidas de tratamento da osteoartrose de joelho em pacientes jovens com desvio do eixo mecânico. A navegação tem sido estudada nos últimos anos como um auxiliar importante nas cirurgias ortopédicas, principalmente artroplastias e oesteotomias. OBJETIVO: Objetivo deste trabalho é comparar, em curto prazo, os resultados radiográficos e clínicos da osteotomia femoral varizante em cunha de adição pelo método convencional e por navegação. MÉTODOS: Avaliamos 25 pacientes no Ambulatório de Especialidades do Hospital Geral de Pedreira, 12 submetidos à osteotomia femoral com navegação e 13 pela técnica convencional. RESULTADOS: Observamos para o grupo da osteotomia com navegação 73, 69 m de tempo de cirurgia com 12, 53 de desvio padrão; 59 m de tempo de garroteamento. Com relação ao alinhamento mecânico, no pré-operatório a média absoluta foi de 13,84 para cirurgia convencional e 14,4 para a técnica com navegação (p= 0.7432; IC95% 12,8 -15,4), No pós-operatório o alinhamento final mecânico variou de -2 a 3 e, não foi diferente entre as técnicas aplicadas (p= 0.1316; IC95% 0,08-1,24). Porém, obtivemos uma alta correlação (p= -0,68) para o grupo com navegação e uma baixa correlação (p= -0,07) para o grupo Resumo Sérgio Ricardo da Costa convencional. CONCLUSÃO: Observamos diferença estatística nos parâmetros: tempo de garroteamento e tempo de cirurgia. Não observamos diferença estatística nos parâmetros: alinhamento mecânico pré e pós; e no escore do HSS / INTRODUCTION: Osteotomies are recognized forms of treatment of knee osteoarthrosis in young patients with mechanical axis deviation. Navigation has been studied in recent years as an important aid in orthopedic surgeries, mainly in arthroplasty and osteotomies. OBJECTIVE: Objective of this study is to compare short-term clinical and radiographic results of femoral varus osteotomy wedge performed by conventional method and by navigation. METHODS: We evaluated 25 patients in Hospital Geral de Pedreira 12 underwent femoral osteotomy with navigation and 13 by conventional technique. RESULTS: As a result, time of surgery was statistically different between techniques (p = 0.0046) with a mean (standard deviation) of 73.69 m (12.53) for the conventional technique and 92.75 m (16.49) technique with navigation. Regarding to mechanical alignment, preoperative mean was 13.84 for conventional surgery and 14.4 for navigation technique (p = 0.7432, 95% CI 12.8 -15.4) Postoperatively final mechanic alignment ranged from -2 to 3, and was not different between the techniques applied (p = 0.1316, 95% CI 0.08 to 1.24). However, we obtained a high correlation (p = -0.68) for the group with navigation and a low correlation (p = -0.07) for the conventional group. CONCLUSION: There were statistical differences in the parameters: time of surgery and tourniquet time. No statistical difference in the parameters: mechanical alignment before and after, and the HSS score

Ho, Wai-to Antony. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 100-102). / Abstracts in English and Chinese. / Abstract --- p.I / Acknowledgement --- p.III / Table of Content --- p.IV / List of Figures --- p.VI / List of Tables --- p.X / List of Charts --- p.XI / Chapter CHAPTER 1: --- INTRODUCTION --- p.1 / Chapter 1.1 --- Biomedical sensing --- p.1 / Chapter 1.2 --- Bone Fracture --- p.2 / Chapter 1.3 --- Bone Fracture Treatment --- p.3 / Chapter 1.4 --- Objectives --- p.4 / Chapter CHAPTER 2: --- LITERATURE SURVEY --- p.5 / Chapter 2.1 --- Bone Structure --- p.5 / Chapter 2.2 --- Biomechanics in Bone Fracture --- p.10 / Chapter 2.3 --- Mathematical Model on Bending and Fracture --- p.11 / Chapter 2.4 --- Intramedullary nailing --- p.12 / Chapter 2.5 --- Reaming technique for intramedullary nailing --- p.14 / Chapter 2.6 --- More on reaming technique --- p.16 / Chapter 2.7 --- Existing pressure-monitoring system of reaming operation --- p.18 / Chapter 2.8 --- Biomedical sensation --- p.19 / Chapter CHAPTER 3: --- SYSTEM DESIGN: RE-ENGINEERING OF A BONE REAMING SYSTEM --- p.23 / Chapter 3.1 --- Mechanical Design-Bone Reaming Guide Rod --- p.23 / Chapter 3.2 --- Guide Rod --- p.24 / Chapter 3.2.1 --- Guide Rod: Head --- p.25 / Chapter 3.2.2 --- Guide Rod: Rod Body --- p.32 / Chapter 3.2.3 --- Guide Rod: Tail --- p.41 / Chapter 3.3 --- Connection System --- p.43 / Chapter 3.3.1 --- Connection System: Components --- p.44 / Chapter 3.3.2 --- Connection System: Connection Mechanism --- p.50 / Chapter 3.3.3 --- Connection System: Disconnection Mechanism --- p.53 / Chapter 3.4 --- Signal Transmission Mechanism --- p.54 / Chapter 3.5 --- Plastic Case --- p.57 / Chapter 3.6 --- Selection of Microsensor --- p.59 / Chapter CHAPTER 4: --- SIGNAL CONDITIONING & PROCESSING --- p.62 / Chapter 4.1 --- Signal Conditioning and Processing --- p.62 / Chapter 4.2 --- Voltage Regulation --- p.62 / Chapter 4.3 --- Instrumentation Amplification --- p.64 / Chapter 4.4 --- Noise Filtering --- p.66 / Chapter 4.5 --- Signal Processing Software --- p.66 / Chapter CHAPTER 5: --- EXPERIMENTAL SETUP --- p.68 / Chapter 5.1 --- Experiments --- p.68 / Chapter 5.2 --- MEMS Pressure Sensor --- p.68 / Chapter 5.3 --- Voltage Regulation Experiment --- p.70 / Chapter 5.4 --- Noise Filtering Experiment --- p.70 / Chapter 5.5 --- Rotating Bearing Signal Transmission System --- p.74 / Chapter 5.6 --- Guide Rod System Calibration Experiment --- p.76 / Chapter 5.6.1 --- Calibration Experiment-Stationary --- p.79 / Chapter 5.6.2 --- Calibration Experiment-Dynamic --- p.79 / Chapter CHAPTER 6: --- EXPERIMENTAL RESULTS --- p.80 / Chapter 6.1 --- Results --- p.80 / Chapter 6.2 --- MEMS Pressure Sensor --- p.80 / Chapter 6.3 --- Voltage Regulation Experiment --- p.81 / Chapter 6.4 --- Noise Filtering Experiment --- p.82 / Chapter 6.5 --- Rotating Bearing Signal Transmission System --- p.83 / Chapter 6.5.1 --- Non-rotating experiment --- p.83 / Chapter 6.5.2 --- Rotating experiment --- p.84 / Chapter 6.5.2.1 --- Rotating experiment -Unprocessed --- p.84 / Chapter 6.5.2.2 --- Rotating experiment -Noise Filtering --- p.86 / Chapter 6.6 --- Guide Rod System Calibration Experiment --- p.89 / Chapter 6.6.1 --- Calibration experiment-Stationary System Calibration --- p.89 / Chapter 6.6.2 --- Rotating experiment-Rotating Speed Calibration --- p.91 / Chapter 6.6.2.1 --- Influence of rotation motion on fluidic pressure --- p.91 / Chapter 6.6.2.2 --- Calibration Experiment --- p.94 / Chapter CHAPTER 7: --- CONCLUSION --- p.98 / Chapter CHAPTER 8: --- REFERENCE --- p.100 / Appendix --- p.103

Diss. (sammanfattning) Stockholm : Karol. inst., 2005. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2005. / Härtill 4 uppsatser.

Thesis (Ph.D.). / Written for the Dept. of Biomedical Engineering. Title from title page of PDF (viewed 2008/05/09). Includes bibliographical references.

INTRODUÇÃO: As osteotomias são formas reconhecidas de tratamento da osteoartrose de joelho em pacientes jovens com desvio do eixo mecânico. A navegação tem sido estudada nos últimos anos como um auxiliar importante nas cirurgias ortopédicas, principalmente artroplastias e oesteotomias. OBJETIVO: Objetivo deste trabalho é comparar, em curto prazo, os resultados radiográficos e clínicos da osteotomia femoral varizante em cunha de adição pelo método convencional e por navegação. MÉTODOS: Avaliamos 25 pacientes no Ambulatório de Especialidades do Hospital Geral de Pedreira, 12 submetidos à osteotomia femoral com navegação e 13 pela técnica convencional. RESULTADOS: Observamos para o grupo da osteotomia com navegação 73, 69 m de tempo de cirurgia com 12, 53 de desvio padrão; 59 m de tempo de garroteamento. Com relação ao alinhamento mecânico, no pré-operatório a média absoluta foi de 13,84 para cirurgia convencional e 14,4 para a técnica com navegação (p= 0.7432; IC95% 12,8 -15,4), No pós-operatório o alinhamento final mecânico variou de -2 a 3 e, não foi diferente entre as técnicas aplicadas (p= 0.1316; IC95% 0,08-1,24). Porém, obtivemos uma alta correlação (p= -0,68) para o grupo com navegação e uma baixa correlação (p= -0,07) para o grupo Resumo Sérgio Ricardo da Costa convencional. CONCLUSÃO: Observamos diferença estatística nos parâmetros: tempo de garroteamento e tempo de cirurgia. Não observamos diferença estatística nos parâmetros: alinhamento mecânico pré e pós; e no escore do HSS / INTRODUCTION: Osteotomies are recognized forms of treatment of knee osteoarthrosis in young patients with mechanical axis deviation. Navigation has been studied in recent years as an important aid in orthopedic surgeries, mainly in arthroplasty and osteotomies. OBJECTIVE: Objective of this study is to compare short-term clinical and radiographic results of femoral varus osteotomy wedge performed by conventional method and by navigation. METHODS: We evaluated 25 patients in Hospital Geral de Pedreira 12 underwent femoral osteotomy with navigation and 13 by conventional technique. RESULTS: As a result, time of surgery was statistically different between techniques (p = 0.0046) with a mean (standard deviation) of 73.69 m (12.53) for the conventional technique and 92.75 m (16.49) technique with navigation. Regarding to mechanical alignment, preoperative mean was 13.84 for conventional surgery and 14.4 for navigation technique (p = 0.7432, 95% CI 12.8 -15.4) Postoperatively final mechanic alignment ranged from -2 to 3, and was not different between the techniques applied (p = 0.1316, 95% CI 0.08 to 1.24). However, we obtained a high correlation (p = -0.68) for the group with navigation and a low correlation (p = -0.07) for the conventional group. CONCLUSION: There were statistical differences in the parameters: time of surgery and tourniquet time. No statistical difference in the parameters: mechanical alignment before and after, and the HSS score

Qi, Lin. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

INTRODUÇÃO: A precisão no posicionamento dos túneis ósseos na reconstrução do ligamento cruzado anterior do joelho (LCA) é considerado um dos fatores fundamentais para o bom resultado dessa cirurgia. A cirurgia ortopédica auxiliada por computador (computer aided orthopedic surgery CAOS) é um avanço tecnológico que tem como um dos principais objetivos exatamente o aumento da precisão. OBJETIVO: comparar o posicionamento do centro dos túneis e a isometria do enxerto obtidos com o uso de um sistema de navegação computadorizada (Orthopilot) e com o uso de guias cirúrgicos convencionais. MÉTODOS: 36 joelhos pareados de cadáveres tiveram o LCA ressecado por artroscopia no Laboratório de Artroscopia do Departamento de Ortopedia e Traumatologia da Faculdade de Medicina da Universidade de São Paulo. Um joelho de cada par foi ramdomizado para o grupo 1 (guias cirúrgicos convencionais) e o outro para o grupo 2 (Orthopilot). Um fio de sutura inelástico foi passado pelo centro dos túneis tibial e femoral confeccionados para a reconstrução do LCA, sem que os túneis fossem finalmente brocados. Todos os joelhos foram então analisados quanto ao posicionamento do centro do túnel tibial (distância do LCP, distância da tubérculo intercondilar medial da tíbia e distância do corno anterior do menisco lateral), do centro do túnel femoral (distância da cortical posterior e angulação coronal na fossa intercondilar do fêmur) e a variação da distância entre os pontos centrais do túnel femoral para o túnel tibial em flexão de 90º e em extensão (isometria). Os dados foram analisados segundo o teste de Wilcoxon para comparação de duas amostras pareadas. RESULTADOS: A variação da distância entre o tunel femoral e tibial em flexão e extensão (isometria) foi maior no grupo 1 convencional, do que no grupo 2 Orthopilot (grupo 1: média 4,2mm com intervalo de 1,1mm a 9,4mm versus grupo 2: média 2,8mm com intervalo de 0,3mm a 6,7mm; p<0,05). Os outros parâmetros analisados não tiveram diferença estatística entre os grupos e demonstraram que todos os túneis dos dois grupos estavam bem posicionados de acordo com os critérios adotados. CONCLUSÕES: O emprego de instrumental cirúrgico navegado pelo sistema Orhtopilot permitiu o posicionamento dos túneis ósseos da reconstrução do LCA de maneira tão precisa quanto os guias cirúrgicos convencionais utilizados. Mais do que isso, proporcionou um posicionamento significativamente mais isométrico nessa série / INTRODUCTION: Precise tunnel location has been considered to be very important to achieve good results in anterior cruciate ligament (ACL) reconstruction surgery. Computer Aided Orthopedic Surgery (CAOS) is a technology improvement whose main objective is to enhance precision. PURPOSE: To compare the accuracy of tunnel placement and graft isometry for ACL reconstruction performed with the use of a computer-assisted navigation system (Orthopilot) and with traditional instruments. METHODS: 36 matched-paired cadaveric knees had their intact ACL removed by arthroscopy at the Arthroscopy Laboratory Orthopedic Department of University of São Paulo Medical School. One knee of each pair was randomized to group 1 (traditional instruments) or group 2 (Orthopilot). An inelastic suture was then passed through the center of where would be the tibial tunnel and then through the center of where would be the femoral tunnel. None of the tunnels were actually drilled. All knees were then dissected and 6 parameters were obtained: The distance from the tibial tunnel center to: 1) the PCL; 2) the lateral meniscus anterior horn; 3) the medial tibial spine. 4) The distance from the femoral tunnel center to the posterior femoral cortex. 5) The femoral tunnel coronal angle. 6) The variation of the distance from the femoral to the tibial tunnels with the knee extended and in 90 degree flexion. The data were submitted to statistical analysis and compared with the Wilcoxon Matched Pairs Test. RESULTS: The variation of the distance from the femoral to the tibial tunnels in flexion and extension was smaller in the Orthopilot group (better isometry): group 1: mean 4.2 mm (1.1-9.4 mm); group 2: mean 2.8 mm (0.3-6.7 mm) p<0,05. All other parameters showed no statistical difference between the groups and all tunnels were considered to be in satisfactory positions. DISCUSSION: There was no difference in tunnel position between the groups. Better isometry was achieved in the Orthopilot group compared to conventional instruments

下颌角缩小术是一种非常流行、有效、并广泛用于修饰脸部轮廓的手术方式。手术中所用到的主要工具有往复锯和圆头磨钻，这两种手术工具工作时有一个共同的特点：通过其高速运转去除骨质。缺乏经验的医生通常需要较长周期的训练，来学习和熟悉如何操作这两种手术工具，并在操作过程中避免由于无法控制好工具与骨骼的触碰以及工具运转时的在骨骼上的移动所造成的危险。具有视觉和触觉反馈的虚拟手术模拟系统为医生们练习手术技巧提供了一种可行并且安全的方式。然而，创建高速运转的手术工具与坚硬的骨骼之间的真实触觉交互模型是一个非常有挑战性的任务。 / 这篇论文设计并实现了虚拟下颌角缩小手术模拟系统，并且创建高保真度的视觉和触觉反馈来增强虚拟手术环境的真实性。文章提出了基于冲量理论的力反馈模型用来模拟作用在工具上的碰撞力和力矩。在不同的往复速率或者旋转速度的情况下，所提出的模型都可以为医生提供可信真实的力感反馈。并且针对磨钻在磨骨是震动明显对磨骨操作有较大影响的特点，论文还提出了一个三维震动模型来模拟磨骨时作用在钻轴上的橫向震动和轴向震动。同时，论文还提出了用于模拟手术中骨质去除以及重建的实时绘制方法。为了验证力模型的真实性，我们还创建了机械平台，采集磨骨和截骨过程中产生的真实力数据，从而用来与虚拟手术中产生的力数据进行比较。最后，还引入真实病人的CT扫描数据来对虚拟手术系统进行实证研究，评估创建的系统是否可以用于训练具有不同手术经验的医生。实证研究的结果也验证了所提出的虚拟手术系统的有效性。 / Mandibular angle reduction is a popular and efficient procedure widely used to alter the facial contour. The primary surgical instruments, the reciprocating saw and the round burr, employed in the surgery have a common feature: operating at a high-speed. Generally, inexperienced surgeons need a longtime practice to learn how to minimize the risks caused by the uncontrolled contacts and cutting motions in manipulation of instruments with high-speed reciprocation or rotation. Virtual reality (VR)-based surgical simulations with both visual and haptic feedbacks provide novice surgeons with a feasible and safe way to practise their surgical skill. However, creating realistic haptic interactions between a high-speed rotary or reciprocating instrument and stiff bone is a challenging task. In this work, a virtual reality-based surgical simulator for the mandibular angle reduction was designed and implemented. High-fidelity visual and haptic feedbacks are provided to enhance the perception in a realistic virtual surgical environment. The impulse-based haptic model was proposed to simulate the contact forces and torques on the instruments. It provides convincing haptic sensation for surgeons to control the instruments under different reciprocation or rotation velocities. Also, in order to mimic the lateral and axial burring vibration forces, a three dimensional vibration model has been developed. The real-time methods for bone removal and reconstruction during surgical procedures have been proposed to support realistic visual feedbacks. The simulated contact forces were verified by comparing against the actual force data measured through the constructed mechanical platform. An empirical study based on the patient-specific data was conducted to evaluate the ability of the proposed system in training surgeons with various experiences. The results confirm the validity of our simulator. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Wang, Qiong. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 100-114). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Abstract --- p.i / Acknowledgement --- p.v / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Contributions of the Thesis --- p.5 / Chapter 1.2 --- Thesis Roadmap --- p.7 / Chapter 2 --- Related Work --- p.9 / Chapter 2.1 --- Virtual Orthopaedic Surgical Simulator --- p.9 / Chapter 2.2 --- Haptic Rendering for Virtual Surgery --- p.11 / Chapter 2.3 --- Evaluation of the Virtual System --- p.14 / Chapter 3 --- System Design --- p.17 / Chapter 3.1 --- Overall System Framework --- p.17 / Chapter 4 --- Bone-burring Surgical Simulation --- p.21 / Chapter 4.1 --- Impulse-Based Modeling of Haptic Simulation of Bone-Burring --- p.22 / Chapter 4.1.1 --- Basic Assumptions --- p.22 / Chapter 4.1.2 --- Bone-Burring Contact Description --- p.25 / Chapter 4.1.3 --- Burring Force Modeling --- p.29 / Chapter 4.2 --- Simulation of Bone Removal --- p.41 / Chapter 4.2.1 --- Bone Removal model --- p.41 / Chapter 4.2.2 --- Adaptive Subdividing Removal Surface --- p.42 / Chapter 4.3 --- Implementation and Experimental Results --- p.52 / Chapter 4.3.1 --- Force Evaluation --- p.53 / Chapter 4.3.2 --- Task-based Evaluation --- p.57 / Chapter 4.3.3 --- Time Performance --- p.61 / Chapter 5 --- Bone-sawing Surgical Simulation --- p.64 / Chapter 5.1 --- Impulse-Based Modeling of Haptic Simulation of Bone-Sawing --- p.65 / Chapter 5.1.1 --- Haptic Saw Instruments Description --- p.65 / Chapter 5.1.2 --- Sawing Force Modeling --- p.67 / Chapter 5.1.3 --- Sawing Torque Constraint --- p.70 / Chapter 5.2 --- Real-time Bone Mesh Reconstruction --- p.74 / Chapter 6 --- Evaluation --- p.78 / Chapter 6.1 --- Haptic Feedback Evaluation --- p.79 / Chapter 6.1.1 --- Mechanical Platform Setup --- p.79 / Chapter 6.1.2 --- Comparison of The Measured and Simulated forces --- p.81 / Chapter 6.2 --- Empirical Study --- p.85 / Chapter 6.2.1 --- Patient Specific Data --- p.87 / Chapter 6.2.2 --- Objective Performance Metrics --- p.89 / Chapter 6.2.3 --- Evaluation Results --- p.90 / Chapter 7 --- Conclusion --- p.94 / Publication List --- p.98 / Bibliography --- p.100

INTRODUÇÃO: A precisão no posicionamento dos túneis ósseos na reconstrução do ligamento cruzado anterior do joelho (LCA) é considerado um dos fatores fundamentais para o bom resultado dessa cirurgia. A cirurgia ortopédica auxiliada por computador (computer aided orthopedic surgery CAOS) é um avanço tecnológico que tem como um dos principais objetivos exatamente o aumento da precisão. OBJETIVO: comparar o posicionamento do centro dos túneis e a isometria do enxerto obtidos com o uso de um sistema de navegação computadorizada (Orthopilot) e com o uso de guias cirúrgicos convencionais. MÉTODOS: 36 joelhos pareados de cadáveres tiveram o LCA ressecado por artroscopia no Laboratório de Artroscopia do Departamento de Ortopedia e Traumatologia da Faculdade de Medicina da Universidade de São Paulo. Um joelho de cada par foi ramdomizado para o grupo 1 (guias cirúrgicos convencionais) e o outro para o grupo 2 (Orthopilot). Um fio de sutura inelástico foi passado pelo centro dos túneis tibial e femoral confeccionados para a reconstrução do LCA, sem que os túneis fossem finalmente brocados. Todos os joelhos foram então analisados quanto ao posicionamento do centro do túnel tibial (distância do LCP, distância da tubérculo intercondilar medial da tíbia e distância do corno anterior do menisco lateral), do centro do túnel femoral (distância da cortical posterior e angulação coronal na fossa intercondilar do fêmur) e a variação da distância entre os pontos centrais do túnel femoral para o túnel tibial em flexão de 90º e em extensão (isometria). Os dados foram analisados segundo o teste de Wilcoxon para comparação de duas amostras pareadas. RESULTADOS: A variação da distância entre o tunel femoral e tibial em flexão e extensão (isometria) foi maior no grupo 1 convencional, do que no grupo 2 Orthopilot (grupo 1: média 4,2mm com intervalo de 1,1mm a 9,4mm versus grupo 2: média 2,8mm com intervalo de 0,3mm a 6,7mm; p<0,05). Os outros parâmetros analisados não tiveram diferença estatística entre os grupos e demonstraram que todos os túneis dos dois grupos estavam bem posicionados de acordo com os critérios adotados. CONCLUSÕES: O emprego de instrumental cirúrgico navegado pelo sistema Orhtopilot permitiu o posicionamento dos túneis ósseos da reconstrução do LCA de maneira tão precisa quanto os guias cirúrgicos convencionais utilizados. Mais do que isso, proporcionou um posicionamento significativamente mais isométrico nessa série / INTRODUCTION: Precise tunnel location has been considered to be very important to achieve good results in anterior cruciate ligament (ACL) reconstruction surgery. Computer Aided Orthopedic Surgery (CAOS) is a technology improvement whose main objective is to enhance precision. PURPOSE: To compare the accuracy of tunnel placement and graft isometry for ACL reconstruction performed with the use of a computer-assisted navigation system (Orthopilot) and with traditional instruments. METHODS: 36 matched-paired cadaveric knees had their intact ACL removed by arthroscopy at the Arthroscopy Laboratory Orthopedic Department of University of São Paulo Medical School. One knee of each pair was randomized to group 1 (traditional instruments) or group 2 (Orthopilot). An inelastic suture was then passed through the center of where would be the tibial tunnel and then through the center of where would be the femoral tunnel. None of the tunnels were actually drilled. All knees were then dissected and 6 parameters were obtained: The distance from the tibial tunnel center to: 1) the PCL; 2) the lateral meniscus anterior horn; 3) the medial tibial spine. 4) The distance from the femoral tunnel center to the posterior femoral cortex. 5) The femoral tunnel coronal angle. 6) The variation of the distance from the femoral to the tibial tunnels with the knee extended and in 90 degree flexion. The data were submitted to statistical analysis and compared with the Wilcoxon Matched Pairs Test. RESULTS: The variation of the distance from the femoral to the tibial tunnels in flexion and extension was smaller in the Orthopilot group (better isometry): group 1: mean 4.2 mm (1.1-9.4 mm); group 2: mean 2.8 mm (0.3-6.7 mm) p<0,05. All other parameters showed no statistical difference between the groups and all tunnels were considered to be in satisfactory positions. DISCUSSION: There was no difference in tunnel position between the groups. Better isometry was achieved in the Orthopilot group compared to conventional instruments