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Frequency and conduction velocity analysis of the abductor pollicis brevis muscle during early fatigue
Track 7. Dental Biomechanics 4241 Tu, 11:45-12:00 (P19) Gender difference in the functional electromyogram of knee extensors B. G6pfert 1, S. Estermann 1, L. K~gi 1, J. Romkes 2, D. Wirz 1. 1Lab. for
Orthopaedic Biomechanics, CM&BE, University of Basel, Switzerland, 2Lab. for Gait Analysis, Children's University Hospital Basel (UKBB), Switzerland The individual bellies of M. quadriceps are responsible for various functions: Rectus-femoris (RF) is a hip flexor, Vastus-lateralis (VL) and Vastus-medialis (VM) are antagonists centralizing the patella and all together they control kneeextension. The aim was to investigate the synchronicity of the intensities in the electromyographic-signal (EMG) between muscles while walking. Methods: Surface-EMG of VL, VM and RF were performed using SENIAMStandard on four healthy female and four male subjects during level walking. The EMG of 12 gate-cycles/subjects were analyzed using wavelet transformation [1]. Results: All female subjects show in a VL, VM and RF bi-summit curve close to the foot-strike whereas males show only in the VM two summits. Male and female show an almost negligible time difference for first major contraction. The second contraction (70ms after foot-strike) is more pronounced in female than male subjects. Discussion: The wavelet-analysis allows a more precise determination of the time of occurrence of muscular events than the classical analysis. Using this method showed the muscular activity of the M. quadriceps occurred in a distinct first and second event separated by 33ms. The muscular events of the three muscle bellies occurred in synchrony (jitter
7.1. Dental Implant Mechanics - Bone-Implant Interaction Phenomena
7658 Tu, 12:15-12:30 (P19) Frequency and conduction velocity analysis of the abductor pollicis brevis muscle during early fatigue M. Barandun 1,2, V. von Tscharner 1, C. Meuli-Simmen 3, V. Bowen 4, V. Valderrabano 1,2,5. 1Human Performance Laboratory, University of Calgary,
Calgary, Alberta, Canada, 2Surgical Department, Stadtspital Triemli, Zurich, Switzerland, 3Division of Reconstructive and Handsurgery, Kantonsspital Aarau, Aarau, Switzerland, 4Orthopaedic Department, University of Calgary, Calgary, Alberta, Canada, 50rthopaedic Department, University Hospital of Basel, Basel, Switzerland The purpose of this study was to assess changes of force and surface electromyograms (sEMG) occurring during the early stage of fatigue of the abductor pollicis brevis (APB) muscle. Thumb abduction force and sEMG were recorded simultaneously during isometric contraction. A multipolar electrode array was used and measurements over the innervation zone (IZ) were avoided. Mean motor unit conduction velocities (MUCV) were computed by a correlation analysis between two selected electrode pairs; mean frequencies (MF) were measured and compared using Fourier (FMF) and wavelet transforms (WMF). Early fatigue resulted in a change of the power spectrum shapes, and a decay of force (-2.1%*s-1), MCUV (-1.5%*s-1), as well as FMF (-4.1%*s-1), and WMF (-3.7%*s -1), respectively. Independent of fatigue, lower MFs were observed at greater distances from the IZ which might reflect a dispersion effect of the MUCV. In conclusion, the decay of the MF in the APB reflects a combination of a decay of MUCV and changes of the spectral shape. This information about the muscle function might be of importance for future assessment of a pathologically altered APB muscle as for instance in the entity of the carpal tunnel syndrome.
Track 7
References [1] V. von Tscharner, J Electromyogr Kinesiol 2003 Jun; 13(3): 253-72. [2] A. Nene, Gait & Posture 2004 Aug; 20(1): 1-13.
Dental B i o m e c h a n i c s
7553 Tu, 12:00-12:15 (P19) Muscle atrophy in ankle osteoarthritis and its rehabilitation with total ankle arthroplasty V. Valderrabano 1,2,3, V. yon Tscharner 1, B.M. Nigg 1, B. G6pfert 3, B. Hintermann 2, W. Dick 2, C.B. Frank 1. 1Human Performance Laboratory
7.1. Dental Implant Mechanics - B o n e - I m p l a n t Interaction Phenomena
and Orthopaedic Department, University of Calgary, Calgary, Canada, 2Orthopaedic Department, University of Basel, Basel, Switzerland, 3Laboratory for Orthopaedic Biomechanics, University of Basel, Basel, Switzerland Purpose: The aim of this prospective study was to assess muscle atrophy in ankle osteoarthritis (OA) and to determine muscle rehabilitation in total ankle replacement (TAR) patients treated for unilateral severe ankle OA. Methods: Fifteen patients were assessed before and after TAR surgery in 3 months intervals up to one-year follow-up. Clinically, pain score, American Orthopaedic Foot and Ankle Society (AOFAS) ankle score, ankle range of motion for dorsi- and plantar flexion (ROM DF/PF), and calf circumference difference between affected and contralateral healthy leg were measured. Radiological assessment consisted of arthritis grading and evaluation of TAR osteointegration. Biomechanically, isometric maximal voluntary torque for ankle DF/PF was measured simultaneously with surface electromyography (EMG; wavelet analysis; mean frequency and intensity) of the anterior tibial, medial gastrocnemius, soleus, and peroneus Iongus muscle. Data was compared to a group of 15 age- and gender-matched normal subjects. Results: From preoperative to 12 months TAR follow-up, the pain score (from 6.8 to 0.8 points), AOFAS ankle score (33.7 to 93.3 points), and ROM DF/PF improved significantly (16.00 to 31.0°). The mean calf circumference difference between legs decreased from 2.1 cm to 1.7 cm, however not significantly. The mean DF-torque (16.4 to 23.1Nm) and PF-torque (15.8 to 21.6Nm) of the affected ankle increased significantly. Compared to the healthy contralateral side, the mean EMG frequency of the atrophic muscles remained low and unchanged during rehabilitation; however, the mean EMG intensity recovered and was not significantly different for all muscles. Discussion: This prospective study provides for the first time new data about ankle OA muscle atrophy and muscle function during the first year rehabilitation process of TAR patients. Patients with end-stage ankle OA can expect from TAR treatment improved ankle function but only partial rehabilitation of the muscle atrophy.
$199
4658 Th, 08:15-08:30 (P38) The influence of abutment angulation on immediate loaded dental implants - A 3D finite element analysis H.-C. Kao 1,2, C.-S. Chen 3, T.-F. Chung 4, C.-K. Cheng 2, M.-L. Hsu 4.
1Biomechanics Research Lab, Medical Research Depart, Mackay Memorial Hospital, Taipei, Taiwan, 2Institute of Biomedical Engineering, National Yang-Ming University, Taipei, Taiwan, 3Institute of Rehabilitation Science & Technology, National Yang-Ming University, Taipei, Taiwan, 4Dental School, National Yang-Ming University, Taipei, Taiwan Immediate loaded dental implant has become popular in recent years. To compensate for the labial bone resorption after tooth extraction in anterior maxillary area, angled abutment may be indicated. The purpose of present study is to investigate the relative movement between implant and bone caused by the implementation of an angled abutment in immediate loading single implant which locates in anterior maxilla. A simplified pre-maxilla bone model was fabricated with 6.5 mm alveolar ridge width and 20 mm in length, which includes a 1 mm thick cortical bone. Immediate loading situation is simulated by press-fitting a 4mm diameter cylinder implant in a 3.15 osteotomy site according to Branemark protocol for Mk IV implant in type III bone. Proper material properties were assigned and only half of the model was meshed to preserve computer resources. A biting force of 178 N, 1200 along abutments long axis, was applied on top of the 0 °, 150 and 250 pre-angled abutments. Relative motion between the bone/implant interfaces was calculated by using ANSYS 9.0 with nonlinear contact algorithm. Under the condition of type III bone, 0.425mm press-fitting level, the micromotion for 150 and 250 preangled abutments were 19.4%, 33.5% more than that of straight abutments, respectively. All these 3 micromotion levels were below the threshold levels to cause fibrous encapsulation. Compared to straight abutments, the 250 abutments increase maximum von Mises stresses by a level of 17.8%. Most of the stresses were concentrated on the cortical bone around implants. Within the limit of this study, it is recommended that angled abutment can be safely applied in immediate loading situation in type III bone of premaxillary single implant prosthesis.
Orthopaedic Biomechanics, CM&BE, University of Basel, Switzerland, 2Lab. for Gait Analysis, Children's University Hospital Basel (UKBB), Switzerland The individual bellies of M. quadriceps are responsible for various functions: Rectus-femoris (RF) is a hip flexor, Vastus-lateralis (VL) and Vastus-medialis (VM) are antagonists centralizing the patella and all together they control kneeextension. The aim was to investigate the synchronicity of the intensities in the electromyographic-signal (EMG) between muscles while walking. Methods: Surface-EMG of VL, VM and RF were performed using SENIAMStandard on four healthy female and four male subjects during level walking. The EMG of 12 gate-cycles/subjects were analyzed using wavelet transformation [1]. Results: All female subjects show in a VL, VM and RF bi-summit curve close to the foot-strike whereas males show only in the VM two summits. Male and female show an almost negligible time difference for first major contraction. The second contraction (70ms after foot-strike) is more pronounced in female than male subjects. Discussion: The wavelet-analysis allows a more precise determination of the time of occurrence of muscular events than the classical analysis. Using this method showed the muscular activity of the M. quadriceps occurred in a distinct first and second event separated by 33ms. The muscular events of the three muscle bellies occurred in synchrony (jitter
7.1. Dental Implant Mechanics - Bone-Implant Interaction Phenomena
7658 Tu, 12:15-12:30 (P19) Frequency and conduction velocity analysis of the abductor pollicis brevis muscle during early fatigue M. Barandun 1,2, V. von Tscharner 1, C. Meuli-Simmen 3, V. Bowen 4, V. Valderrabano 1,2,5. 1Human Performance Laboratory, University of Calgary,
Calgary, Alberta, Canada, 2Surgical Department, Stadtspital Triemli, Zurich, Switzerland, 3Division of Reconstructive and Handsurgery, Kantonsspital Aarau, Aarau, Switzerland, 4Orthopaedic Department, University of Calgary, Calgary, Alberta, Canada, 50rthopaedic Department, University Hospital of Basel, Basel, Switzerland The purpose of this study was to assess changes of force and surface electromyograms (sEMG) occurring during the early stage of fatigue of the abductor pollicis brevis (APB) muscle. Thumb abduction force and sEMG were recorded simultaneously during isometric contraction. A multipolar electrode array was used and measurements over the innervation zone (IZ) were avoided. Mean motor unit conduction velocities (MUCV) were computed by a correlation analysis between two selected electrode pairs; mean frequencies (MF) were measured and compared using Fourier (FMF) and wavelet transforms (WMF). Early fatigue resulted in a change of the power spectrum shapes, and a decay of force (-2.1%*s-1), MCUV (-1.5%*s-1), as well as FMF (-4.1%*s-1), and WMF (-3.7%*s -1), respectively. Independent of fatigue, lower MFs were observed at greater distances from the IZ which might reflect a dispersion effect of the MUCV. In conclusion, the decay of the MF in the APB reflects a combination of a decay of MUCV and changes of the spectral shape. This information about the muscle function might be of importance for future assessment of a pathologically altered APB muscle as for instance in the entity of the carpal tunnel syndrome.
Track 7
References [1] V. von Tscharner, J Electromyogr Kinesiol 2003 Jun; 13(3): 253-72. [2] A. Nene, Gait & Posture 2004 Aug; 20(1): 1-13.
Dental B i o m e c h a n i c s
7553 Tu, 12:00-12:15 (P19) Muscle atrophy in ankle osteoarthritis and its rehabilitation with total ankle arthroplasty V. Valderrabano 1,2,3, V. yon Tscharner 1, B.M. Nigg 1, B. G6pfert 3, B. Hintermann 2, W. Dick 2, C.B. Frank 1. 1Human Performance Laboratory
7.1. Dental Implant Mechanics - B o n e - I m p l a n t Interaction Phenomena
and Orthopaedic Department, University of Calgary, Calgary, Canada, 2Orthopaedic Department, University of Basel, Basel, Switzerland, 3Laboratory for Orthopaedic Biomechanics, University of Basel, Basel, Switzerland Purpose: The aim of this prospective study was to assess muscle atrophy in ankle osteoarthritis (OA) and to determine muscle rehabilitation in total ankle replacement (TAR) patients treated for unilateral severe ankle OA. Methods: Fifteen patients were assessed before and after TAR surgery in 3 months intervals up to one-year follow-up. Clinically, pain score, American Orthopaedic Foot and Ankle Society (AOFAS) ankle score, ankle range of motion for dorsi- and plantar flexion (ROM DF/PF), and calf circumference difference between affected and contralateral healthy leg were measured. Radiological assessment consisted of arthritis grading and evaluation of TAR osteointegration. Biomechanically, isometric maximal voluntary torque for ankle DF/PF was measured simultaneously with surface electromyography (EMG; wavelet analysis; mean frequency and intensity) of the anterior tibial, medial gastrocnemius, soleus, and peroneus Iongus muscle. Data was compared to a group of 15 age- and gender-matched normal subjects. Results: From preoperative to 12 months TAR follow-up, the pain score (from 6.8 to 0.8 points), AOFAS ankle score (33.7 to 93.3 points), and ROM DF/PF improved significantly (16.00 to 31.0°). The mean calf circumference difference between legs decreased from 2.1 cm to 1.7 cm, however not significantly. The mean DF-torque (16.4 to 23.1Nm) and PF-torque (15.8 to 21.6Nm) of the affected ankle increased significantly. Compared to the healthy contralateral side, the mean EMG frequency of the atrophic muscles remained low and unchanged during rehabilitation; however, the mean EMG intensity recovered and was not significantly different for all muscles. Discussion: This prospective study provides for the first time new data about ankle OA muscle atrophy and muscle function during the first year rehabilitation process of TAR patients. Patients with end-stage ankle OA can expect from TAR treatment improved ankle function but only partial rehabilitation of the muscle atrophy.
$199
4658 Th, 08:15-08:30 (P38) The influence of abutment angulation on immediate loaded dental implants - A 3D finite element analysis H.-C. Kao 1,2, C.-S. Chen 3, T.-F. Chung 4, C.-K. Cheng 2, M.-L. Hsu 4.
1Biomechanics Research Lab, Medical Research Depart, Mackay Memorial Hospital, Taipei, Taiwan, 2Institute of Biomedical Engineering, National Yang-Ming University, Taipei, Taiwan, 3Institute of Rehabilitation Science & Technology, National Yang-Ming University, Taipei, Taiwan, 4Dental School, National Yang-Ming University, Taipei, Taiwan Immediate loaded dental implant has become popular in recent years. To compensate for the labial bone resorption after tooth extraction in anterior maxillary area, angled abutment may be indicated. The purpose of present study is to investigate the relative movement between implant and bone caused by the implementation of an angled abutment in immediate loading single implant which locates in anterior maxilla. A simplified pre-maxilla bone model was fabricated with 6.5 mm alveolar ridge width and 20 mm in length, which includes a 1 mm thick cortical bone. Immediate loading situation is simulated by press-fitting a 4mm diameter cylinder implant in a 3.15 osteotomy site according to Branemark protocol for Mk IV implant in type III bone. Proper material properties were assigned and only half of the model was meshed to preserve computer resources. A biting force of 178 N, 1200 along abutments long axis, was applied on top of the 0 °, 150 and 250 pre-angled abutments. Relative motion between the bone/implant interfaces was calculated by using ANSYS 9.0 with nonlinear contact algorithm. Under the condition of type III bone, 0.425mm press-fitting level, the micromotion for 150 and 250 preangled abutments were 19.4%, 33.5% more than that of straight abutments, respectively. All these 3 micromotion levels were below the threshold levels to cause fibrous encapsulation. Compared to straight abutments, the 250 abutments increase maximum von Mises stresses by a level of 17.8%. Most of the stresses were concentrated on the cortical bone around implants. Within the limit of this study, it is recommended that angled abutment can be safely applied in immediate loading situation in type III bone of premaxillary single implant prosthesis.