- Email: [email protected]
Paper # 2: Knee Biomechanics in Patients with Computer-Assisted Navigation TKA More Closely Resemble Normal Gait than those with Conventional TKA
e70
ABSTRACTS
results of over 30 patients who have received this surgical technique. Our study supports the use of the bicompartmental or segmental resurfacing techniques in specially selected appropriate patients which we consider an important adjunct in the knee resurfacing options for the younger patient with significant arthritis and would support the use of our surgical technique. The authors recommend continued use of this technique whilst awaiting mid-term and long-term data to further validate this surgical procedure. Paper # 2: Knee Biomechanics in Patients with Computer-Assisted Navigation TKA More Closely Resemble Normal Gait than those with Conventional TKA JODIE A MCCLELLAND, PHD, USA KATE E. WEBSTER, PHD, AUSTRALIA JULIAN A. FELLER, FRACS, AUSTRALIA JOANNE WITTWER, MS, AUSTRALIA · La Trobe University Melbourne, VIC, AUSTRALIA Summary: Patients with Navigation TKA walked with fewer biomechanical differences from healthy controls than those with Conventional TKA. Abstract: Introduction: Computer-assisted navigation has been shown to improve consistency in the accuracy of coronal plane alignment of the lower limb following Total Knee Arthroplasty (TKA). However, there is limited evidence that these improvements in alignment lead to superior functional outcomes for patients. The purpose of this study was to compare the functional knee biomechanics during walking between patients with either computerassisted navigation or conventional TKA and a control population without knee pathology. Methods: Eighty-one patients (39 with conventional TKA and 42 with computer-assisted navigation TKA) and 40 unimpaired control participants were assessed during comfortable speed walking using an 8 camera motion analysis system. The mechanical axis and weightbearing line were measured from standing long leg radiographs. Peak knee angles and moments in the sagittal, coronal and transverse planes were compared between groups. The individual waveforms of all participants were also analyzed for the presence of either a normal of abnormal pattern, based on the magnitude and timing of the knee flexor moment. Results: The mechanical axis and weightbearing line in patients with Navigation TKA (179°⫾2; 46⫾1%) were significantly different from Conventional TKA (177°⫾4; 36⫾2%; p⬍0.01, p⫽0.01). The Conventional TKA pa-
tients walked at a slower speed than both the Navigation TKA patients and the control participants (p⬍0.01). When this difference in walking speed between groups was accounted for, there were no differences between the Navigation TKA and control groups in either the sagittal plane or coronal plane angles. In contrast, compared to the control group the Conventional TKA group walked with less knee flexion during weight acceptance (p⫽0.02) and less knee flexion during swing (p⫽0.04). Both the Navigation TKA and Conventional TKA groups walked with less maximum internal and greater maximum external rotation than controls (p⬍0.01). The maximum knee flexor moment was not significantly different between groups, but the maximum adductor moment was reduced in both TKA groups in comparison to controls (p⬍0.01). When the individual moment profiles of all participants were analysed, 97% of the control group were classified as normal compared to 87% of the Navigation TKA group and 68% of the Conventional TKA group (p⬍0.01). Discussion: Patients with Navigation TKA walked with fewer biomechanical differences from healthy controls than those with Conventional TKA. In particular, the restricted knee flexion angles and abnormal knee moments during gait that are typically seen in patients following TKA were not present in those treated with computer-assisted Navigation. It appears that Navigation TKA leads to gait biomechanics that are closer to normal than Conventional TKA. Paper # 3: Patient-Specific Cutting Block in TKR: Comparison Between CT and MRI 3D Planning DANIEL FRITSCHY, MD, SWITZERLAND GUY MESSERLI, MD, SWITZERLAND · Service de Chirurgie Orthopédique et Traumatologie Geneva, SWITZERLAND Summary: 3D CT planning of patient-specific cutting blocks for TKR is possible : like with MRI data, the precision in surgery is excellent Abstract: Introduction: The last innovation in the field of knee joint replacement technique is the use of customized cutting blocks which are produced individually for each patient. The production of these guides is based on MRI data. The purpose of this study is to compare the precision of MRI and CT in the design and production of patientspecific cutting blocks. Material and Methods: A first experiment has been realized with 3 human specimens on which MRI and CT
ABSTRACTS
results of over 30 patients who have received this surgical technique. Our study supports the use of the bicompartmental or segmental resurfacing techniques in specially selected appropriate patients which we consider an important adjunct in the knee resurfacing options for the younger patient with significant arthritis and would support the use of our surgical technique. The authors recommend continued use of this technique whilst awaiting mid-term and long-term data to further validate this surgical procedure. Paper # 2: Knee Biomechanics in Patients with Computer-Assisted Navigation TKA More Closely Resemble Normal Gait than those with Conventional TKA JODIE A MCCLELLAND, PHD, USA KATE E. WEBSTER, PHD, AUSTRALIA JULIAN A. FELLER, FRACS, AUSTRALIA JOANNE WITTWER, MS, AUSTRALIA · La Trobe University Melbourne, VIC, AUSTRALIA Summary: Patients with Navigation TKA walked with fewer biomechanical differences from healthy controls than those with Conventional TKA. Abstract: Introduction: Computer-assisted navigation has been shown to improve consistency in the accuracy of coronal plane alignment of the lower limb following Total Knee Arthroplasty (TKA). However, there is limited evidence that these improvements in alignment lead to superior functional outcomes for patients. The purpose of this study was to compare the functional knee biomechanics during walking between patients with either computerassisted navigation or conventional TKA and a control population without knee pathology. Methods: Eighty-one patients (39 with conventional TKA and 42 with computer-assisted navigation TKA) and 40 unimpaired control participants were assessed during comfortable speed walking using an 8 camera motion analysis system. The mechanical axis and weightbearing line were measured from standing long leg radiographs. Peak knee angles and moments in the sagittal, coronal and transverse planes were compared between groups. The individual waveforms of all participants were also analyzed for the presence of either a normal of abnormal pattern, based on the magnitude and timing of the knee flexor moment. Results: The mechanical axis and weightbearing line in patients with Navigation TKA (179°⫾2; 46⫾1%) were significantly different from Conventional TKA (177°⫾4; 36⫾2%; p⬍0.01, p⫽0.01). The Conventional TKA pa-
tients walked at a slower speed than both the Navigation TKA patients and the control participants (p⬍0.01). When this difference in walking speed between groups was accounted for, there were no differences between the Navigation TKA and control groups in either the sagittal plane or coronal plane angles. In contrast, compared to the control group the Conventional TKA group walked with less knee flexion during weight acceptance (p⫽0.02) and less knee flexion during swing (p⫽0.04). Both the Navigation TKA and Conventional TKA groups walked with less maximum internal and greater maximum external rotation than controls (p⬍0.01). The maximum knee flexor moment was not significantly different between groups, but the maximum adductor moment was reduced in both TKA groups in comparison to controls (p⬍0.01). When the individual moment profiles of all participants were analysed, 97% of the control group were classified as normal compared to 87% of the Navigation TKA group and 68% of the Conventional TKA group (p⬍0.01). Discussion: Patients with Navigation TKA walked with fewer biomechanical differences from healthy controls than those with Conventional TKA. In particular, the restricted knee flexion angles and abnormal knee moments during gait that are typically seen in patients following TKA were not present in those treated with computer-assisted Navigation. It appears that Navigation TKA leads to gait biomechanics that are closer to normal than Conventional TKA. Paper # 3: Patient-Specific Cutting Block in TKR: Comparison Between CT and MRI 3D Planning DANIEL FRITSCHY, MD, SWITZERLAND GUY MESSERLI, MD, SWITZERLAND · Service de Chirurgie Orthopédique et Traumatologie Geneva, SWITZERLAND Summary: 3D CT planning of patient-specific cutting blocks for TKR is possible : like with MRI data, the precision in surgery is excellent Abstract: Introduction: The last innovation in the field of knee joint replacement technique is the use of customized cutting blocks which are produced individually for each patient. The production of these guides is based on MRI data. The purpose of this study is to compare the precision of MRI and CT in the design and production of patientspecific cutting blocks. Material and Methods: A first experiment has been realized with 3 human specimens on which MRI and CT