Unicompartmental knee replacement for selected cases of osteoarthritis is less invasive than total knee replacement. It gives better range of movement; patients stay for shorter time in the hospital and have a more natural feel than total knee replacement. Usually, the implant is fixed in the bone using bone cement. However, there are potential disadvantages of using bone cement. The operation takes longer; cement can get squeezed out into the surrounding tissues and may interfere with function. To avoid these problems, the implant can be fixed without cement. Cementless components have a special coating to encourage bone in-growth and fixation. Although the investigators believe cementless fixation will be at least as good as cemented fixation, there is a risk that it could be worse and might result in loosening. The aim of this study is therefore to compare the outcome of cemented and cementless unicompartmental knee replacement.
Design: A prospective, randomised trial to compare the outcome of cemented and cementless unicompartmental knee replacement. Size: 40 subjects in total will be recruited with 20 in each arm. Methods: Patients will be recruited from the routine waiting list for unicompartmental knee replacement at the Nuffield Orthopaedic Centre. All subjects will have the procedure explained and be fully consented prior to the procedure. Randomisation: Patients will be randomly allocated to receive either a cemented or cementless Oxford Unicompartmental Knee Replacement. This will be performed using a randomisation program based on optimisation (Minim). Subjects will be stratified according to sex and age. Operation: All subjects will undergo the same surgical approach. 0.8mm Tantalum marker balls will be placed at standardised sites on the femur and tibia in all cases. All cemented components will be secured using the same cement. Cementless components have a hydroxy-appatite coating to facilitate bone ingrowth. Follow-up: All patients will be followed up at 0, 3, 6, 12, 24, 60, and 120 months with clinical and radiological assessment. Clinical assessment will involve documentation with the Oxford Knee Score. Patients will undergo radiostereometric analysis and fluoroscopy to study implant migration and occurence of radiolucency, respectively.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Enrollment
47
All patients will undergo the same surgical approach. 0.8mm diameter tantalum marker balls will be placed in the tibia and femur in all cases. Cementless components have a hydroxy-appatite coating to facilitate bone ingrowth. The cementless femoral component also has a smaller second peg, located anteriorly to the larger central peg that is also present of the cemented femoral component.
All patients will undergo the same surgical approach. 0.8mm diameter tantalum marker balls will be placed in the tibia and femur in all cases. All cemented components will be secured using the same cement.
Radiostereometric Analysis Examination - Translations
Patients will have weight-bearing stereoradiographs. These stereoradiographs will be analysed using model-based radiostereometric analysis which will allow the migration of the components relative to the bone to be determined. Three-dimensional translations will be measured in millimetres. The component position at the post-operative timepoint was used as the baseline for measurement of migration. Migration can be interpreted as: * X translation: Positive (+ve) = Medial; Negative (-ve) = Lateral * Y translation: Positive (+ve) = Superior; Negative (-ve) = Inferior * Z translation: Positive (+ve) = Anterior; Negative (-ve) = Posterior
Time frame: Patients will be examined 3 months post surgery.
Radiostereometric Analysis Examination - Translations
Patients will have weight-bearing stereoradiographs. These stereoradiographs will be analysed using model-based radiostereometric analysis which will allow the migration of the components relative to the bone to be determined. Three-dimensional translations will be measured in millimetres. The component position at the post-operative timepoint was used as the baseline for measurement of migration. Migration can be interpreted as: * X translation: Positive (+ve) = Medial; Negative (-ve) = Lateral * Y translation: Positive (+ve) = Superior; Negative (-ve) = Inferior * Z translation: Positive (+ve) = Anterior; Negative (-ve) = Posterior
Time frame: Patients will be examined 6 months post surgery.
Radiostereometric Analysis Examination - Translations
Patients will have weight-bearing stereoradiographs. These stereoradiographs will be analysed using model-based radiostereometric analysis which will allow the migration of the components relative to the bone to be determined. Three-dimensional translations will be measured in millimetres. The component position at the post-operative timepoint was used as the baseline for measurement of migration. Migration can be interpreted as: * X translation: Positive (+ve) = Medial; Negative (-ve) = Lateral * Y translation: Positive (+ve) = Superior; Negative (-ve) = Inferior * Z translation: Positive (+ve) = Anterior; Negative (-ve) = Posterior
Time frame: Patients will be examined 12 months post surgery.
Radiostereometric Analysis Examination - Translations
Patients will have weight-bearing stereoradiographs. These stereoradiographs will be analysed using model-based radiostereometric analysis which will allow the migration of the components relative to the bone to be determined. Three-dimensional translations will be measured in millimetres. The component position at the post-operative timepoint was used as the baseline for measurement of migration. Migration can be interpreted as: * X translation: Positive (+ve) = Medial; Negative (-ve) = Lateral * Y translation: Positive (+ve) = Superior; Negative (-ve) = Inferior * Z translation: Positive (+ve) = Anterior; Negative (-ve) = Posterior
Time frame: Patients will be examined 24 months post surgery.
Radiostereometric Analysis Examination - Translations
Patients will have weight-bearing stereoradiographs. These stereoradiographs will be analysed using model-based radiostereometric analysis which will allow the migration of the components relative to the bone to be determined. Three-dimensional translations will be measured in millimetres.
Time frame: Patients will be examined 60 months post surgery.
Radiostereometric Analysis Examination - Translations
Patients will have weight-bearing stereoradiographs. These stereoradiographs will be analysed using model-based radiostereometric analysis which will allow the migration of the components relative to the bone to be determined. Three-dimensional translations will be measured in millimetres. The component position at the post-operative timepoint was used as the baseline for measurement of migration. Migration can be interpreted as: * X translation: Positive (+ve) = Medial; Negative (-ve) = Lateral * Y translation: Positive (+ve) = Superior; Negative (-ve) = Inferior * Z translation: Positive (+ve) = Anterior; Negative (-ve) = Posterior
Time frame: Patients will be examined 120 months post surgery.
Radiostereometric Analysis Examination - Rotations
Patients will have weight-bearing stereoradiographs. These stereoradiographs will be analysed using model-based radiostereometric analysis which will allow the migration of the components relative to the bone to be determined. Three-dimensional rotations will be measured in degrees.The component position at the post-operative timepoint was used as the baseline for measurement of migration. Migration can be interpreted as: \*For the Femoral Component\* X Rotation: Positive (+ve) = Increased Flexion; Negative (-ve) = Decreased Flexion Y Rotation: Positive (+ve) = Internal Rotation; Negative (-ve) = External Rotation Z Rotation: Positive (+ve) = Valgus; Negative (-ve) = Varus \*For the Tibial Component\* X Rotation: Positive (+ve) = Reduced Slope; Negative (-ve) = Increased Slope Y Rotation: Positive (+ve) = Internal Rotation; Negative (-ve) = External Rotation Z Rotation: Positive (+ve) = Valgus; Negative (-ve) = Varus
Time frame: Patients will be examined at 3 months post surgery.
Radiostereometric Analysis Examination - Rotations
Patients will have weight-bearing stereoradiographs. These stereoradiographs will be analysed using model-based radiostereometric analysis which will allow the migration of the components relative to the bone to be determined. Three-dimensional rotations will be measured in degrees.The component position at the post-operative timepoint was used as the baseline for measurement of migration. Migration can be interpreted as: * For the Femoral Component\* X Rotation: Positive (+ve) = Increased Flexion; Negative (-ve) = Decreased Flexion Y Rotation: Positive (+ve) = Internal Rotation; Negative (-ve) = External Rotation Z Rotation: Positive (+ve) = Valgus; Negative (-ve) = Varus * For the Tibial Component\* X Rotation: Positive (+ve) = Reduced Slope; Negative (-ve) = Increased Slope Y Rotation: Positive (+ve) = Internal Rotation; Negative (-ve) = External Rotation Z Rotation: Positive (+ve) = Valgus; Negative (-ve) = Varus
Time frame: Patients will be examined at 6 months post surgery.
Radiostereometric Analysis Examination - Rotations
Patients will have weight-bearing stereoradiographs. These stereoradiographs will be analysed using model-based radiostereometric analysis which will allow the migration of the components relative to the bone to be determined. Three-dimensional rotations will be measured in degrees.The component position at the post-operative timepoint was used as the baseline for measurement of migration. Migration can be interpreted as: * For the Femoral Component\* X Rotation: Positive (+ve) = Increased Flexion; Negative (-ve) = Decreased Flexion Y Rotation: Positive (+ve) = Internal Rotation; Negative (-ve) = External Rotation Z Rotation: Positive (+ve) = Valgus; Negative (-ve) = Varus * For the Tibial Component\* X Rotation: Positive (+ve) = Reduced Slope; Negative (-ve) = Increased Slope Y Rotation: Positive (+ve) = Internal Rotation; Negative (-ve) = External Rotation Z Rotation: Positive (+ve) = Valgus; Negative (-ve) = Varus
Time frame: Patients will be examined at 12 months post surgery.
Radiostereometric Analysis Examination - Rotations
Patients will have weight-bearing stereoradiographs. These stereoradiographs will be analysed using model-based radiostereometric analysis which will allow the migration of the components relative to the bone to be determined. Three-dimensional rotations will be measured in degrees.The component position at the post-operative timepoint was used as the baseline for measurement of migration. Migration can be interpreted as: * For the Femoral Component\* X Rotation: Positive (+ve) = Increased Flexion; Negative (-ve) = Decreased Flexion Y Rotation: Positive (+ve) = Internal Rotation; Negative (-ve) = External Rotation Z Rotation: Positive (+ve) = Valgus; Negative (-ve) = Varus * For the Tibial Component\* X Rotation: Positive (+ve) = Reduced Slope; Negative (-ve) = Increased Slope Y Rotation: Positive (+ve) = Internal Rotation; Negative (-ve) = External Rotation Z Rotation: Positive (+ve) = Valgus; Negative (-ve) = Varus
Time frame: Patients will be examined at 24 months post surgery.
Radiostereometric Analysis Examination - Rotations
Patients will have weight-bearing stereoradiographs. These stereoradiographs will be analysed using model-based radiostereometric analysis which will allow the migration of the components relative to the bone to be determined. Three-dimensional rotations will be measured in degrees.The component position at the post-operative timepoint was used as the baseline for measurement of migration. Migration can be interpreted as: * For the Femoral Component\* X Rotation: Positive (+ve) = Increased Flexion; Negative (-ve) = Decreased Flexion Y Rotation: Positive (+ve) = Internal Rotation; Negative (-ve) = External Rotation Z Rotation: Positive (+ve) = Valgus; Negative (-ve) = Varus * For the Tibial Component\* X Rotation: Positive (+ve) = Reduced Slope; Negative (-ve) = Increased Slope Y Rotation: Positive (+ve) = Internal Rotation; Negative (-ve) = External Rotation Z Rotation: Positive (+ve) = Valgus; Negative (-ve) = Varus
Time frame: Patients will be examined at 60 months post surgery.
Radiostereometric Analysis Examination - Rotations
Patients will have weight-bearing stereoradiographs. These stereoradiographs will be analysed using model-based radiostereometric analysis which will allow the migration of the components relative to the bone to be determined. Three-dimensional rotations will be measured in degrees.The component position at the post-operative timepoint was used as the baseline for measurement of migration. Migration can be interpreted as: * For the Femoral Component\* X Rotation: Positive (+ve) = Increased Flexion; Negative (-ve) = Decreased Flexion Y Rotation: Positive (+ve) = Internal Rotation; Negative (-ve) = External Rotation Z Rotation: Positive (+ve) = Valgus; Negative (-ve) = Varus * For the Tibial Component\* X Rotation: Positive (+ve) = Reduced Slope; Negative (-ve) = Increased Slope Y Rotation: Positive (+ve) = Internal Rotation; Negative (-ve) = External Rotation Z Rotation: Positive (+ve) = Valgus; Negative (-ve) = Varus
Time frame: Patients will be examined at 120 months post surgery.
Radiostereometric Analysis Examination - Maximum Total Point Motion
Patients will have weight-bearing stereoradiographs. These stereoradiographs will be analysed using model-based radiostereometric analysis which will allow the migration of the components relative to the bone to be determined. Maximum Total Point Motion (MTPM - defined as the length of the translation vector of the point of the component model that has migrated the most) will be measured in millimetres.
Time frame: Patients will be examined at 3 months post surgery.
Radiostereometric Analysis Examination - Maximum Total Point Motion
Patients will have weight-bearing stereoradiographs. These stereoradiographs will be analysed using model-based radiostereometric analysis which will allow the migration of the components relative to the bone to be determined. Maximum Total Point Motion (MTPM - defined as the length of the translation vector of the point of the component model that has migrated the most) will be measured in millimetres.
Time frame: Patients will be examined at 12 months post surgery.
Radiostereometric Analysis Examination - Maximum Total Point Motion
Patients will have weight-bearing stereoradiographs. These stereoradiographs will be analysed using model-based radiostereometric analysis which will allow the migration of the components relative to the bone to be determined. Maximum Total Point Motion (MTPM - defined as the length of the translation vector of the point of the component model that has migrated the most) will be measured in millimetres.
Time frame: Patients will be examined at 24 months post surgery.
Radiostereometric Analysis Examination - Maximum Total Point Motion
Patients will have weight-bearing stereoradiographs. These stereoradiographs will be analysed using model-based radiostereometric analysis which will allow the migration of the components relative to the bone to be determined. Maximum Total Point Motion (MTPM - defined as the length of the translation vector of the point of the component model that has migrated the most) will be measured in millimetres.
Time frame: Patients will be examined at 60 months post surgery.
Radiostereometric Analysis Examination - Maximum Total Point Motion
Patients will have weight-bearing stereoradiographs. These stereoradiographs will be analysed using model-based radiostereometric analysis which will allow the migration of the components relative to the bone to be determined. Maximum Total Point Motion (MTPM - defined as the length of the translation vector of the point of the component model that has migrated the most) will be measured in millimetres.
Time frame: Patients will be examined at 120 months post surgery.
Radiographic Examination
Fluoroscopic imaging will be used to study the occurence of radiolucencies beneath the components. Anteroposterior radiographs will be analysed to assess the presence and position of radiolucencies. Radiolucencies will be graded as either 'no radiolucency present', 'partial radiolucency', or 'complete radiolucency'.
Time frame: Patients will be examined at 12 months post surgery.
Radiographic Examination
Fluoroscopic imaging will be used to study the occurence of radiolucencies beneath the components. Anteroposterior radiographs will be analysed to assess the presence and position of radiolucencies. Radiolucencies will be graded as either 'no radiolucency present', 'partial radiolucency', or 'complete radiolucency'.
Time frame: Patients will be examined at 24 months post surgery.
Radiographic Examination
Fluoroscopic imaging will be used to study the occurence of radiolucencies beneath the components. Anteroposterior radiographs will be analysed to assess the presence and position of radiolucencies. Radiolucencies will be graded as either 'no radiolucency present', 'partial radiolucency', or 'complete radiolucency'.
Time frame: Patients will be examined at 60 months post surgery.
Radiographic Examination
Fluoroscopic imaging will be used to study the occurence of radiolucencies beneath the components. Anteroposterior radiographs will be analysed to assess the presence and position of radiolucencies. Radiolucencies will be graded as either 'no radiolucency present', 'partial radiolucency', or 'complete radiolucency'.
Time frame: Patients will be examined at 120 months post surgery.
Clinical Assessment
Clinical assessment will involve documentation with the Oxford Knee Score. The score will be calculated on a scale of 0 (worst) to 48 (best).
Time frame: Patients will be assessed pre-operatively.
Clinical Assessment
Clinical assessment will involve documentation with the Oxford Knee Score. The score will be calculated on a scale of 0 (worst) to 48 (best).
Time frame: Patients will be assessed at 12 months post surgery.
Clinical Assessment
Clinical assessment will involve documentation with the Oxford Knee Score. The score will be calculated on a scale of 0 (worst) to 48 (best).
Time frame: Patients will be assessed at 24 months post surgery.
Clinical Assessment
Clinical assessment will involve documentation with the Oxford Knee Score. The score will be calculated on a scale of 0 (worst) to 48 (best).
Time frame: Patients will be assessed at 60 months post surgery.
Clinical Assessment
Clinical assessment will involve documentation with the Oxford Knee Score. The score will be calculated on a scale of 0 (worst) to 48 (best).
Time frame: Patients will be assessed at 120 months post surgery.
Radiostereometric Analysis Examination - Maximum Total Point Motion
Patients will have weight-bearing stereoradiographs. These stereoradiographs will be analysed using model-based radiostereometric analysis which will allow the migration of the components relative to the bone to be determined. Maximum Total Point Motion (MTPM - defined as the length of the translation vector of the point of the component model that has migrated the most) will be measured in millimetres.
Time frame: Patients will be assessed at 6 months post surgery.
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