Trial Outcomes & Findings for Cemented Versus Cementless Unicompartmental Knee Arthroplasty (NCT NCT05935878)

Results Overview

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

Recruitment status

COMPLETED

Study phase

NA

Target enrollment

47 participants

Primary outcome timeframe

Patients will be examined 3 months post surgery.

Results posted on

2024-09-23

Participant Flow

A consecutive series of patients awairing an Oxford Unicompartmental Knee Replacement (OUKR) were invited to participate in the study. Consenting participants received an OUKR between November 2008 and March 2010 at the Nuffield Orthopaedic Centre (Oxford, UK).

Participant milestones

Participant milestones
Measure	Cementless Oxford Unicompartmental Knee Arthroplasty Phase III Cementless Oxford Unicompartmental Knee Replacement (Biomet) Cementless Oxford Unicompartmental Knee Arthroplasty: 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.	Cemented Oxford Unicompartmental Knee Arthroplasty Phase III Cemented Oxford Unicompartmental Knee Replacement (Biomet) Cemented Oxford Unicompartmental Knee Arthroplasty: 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.
Overall Study STARTED	23	24
Overall Study 1 Year	22	21
Overall Study 2 Years	22	21
Overall Study 5 Years	19	20
Overall Study 10 Years	16	15
Overall Study COMPLETED	16	15
Overall Study NOT COMPLETED	7	9

Reasons for withdrawal

Reasons for withdrawal
Measure	Cementless Oxford Unicompartmental Knee Arthroplasty Phase III Cementless Oxford Unicompartmental Knee Replacement (Biomet) Cementless Oxford Unicompartmental Knee Arthroplasty: 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.	Cemented Oxford Unicompartmental Knee Arthroplasty Phase III Cemented Oxford Unicompartmental Knee Replacement (Biomet) Cemented Oxford Unicompartmental Knee Arthroplasty: 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.
Overall Study Death	1	2
Overall Study Withdrawal by Subject	5	5
Overall Study Revision of implant	1	1
Overall Study Mobile bearing dislocation	0	1

Baseline Characteristics

Race and Ethnicity were not collected from any participant.

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	Cementless Oxford Unicompartmental Knee Arthroplasty n=23 Participants Phase III Cementless Oxford Unicompartmental Knee Replacement (Biomet) Cementless Oxford Unicompartmental Knee Arthroplasty: 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.	Cemented Oxford Unicompartmental Knee Arthroplasty n=24 Participants Phase III Cemented Oxford Unicompartmental Knee Replacement (Biomet) Cemented Oxford Unicompartmental Knee Arthroplasty: 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.	Total n=47 Participants Total of all reporting groups
Age, Categorical <=18 years	0 Participants n=23 Participants	0 Participants n=24 Participants	0 Participants n=47 Participants
Age, Categorical Between 18 and 65 years	8 Participants n=23 Participants	11 Participants n=24 Participants	19 Participants n=47 Participants
Age, Categorical >=65 years	15 Participants n=23 Participants	13 Participants n=24 Participants	28 Participants n=47 Participants
Age, Continuous	67.7 years n=23 Participants	65.9 years n=24 Participants	66.7 years n=47 Participants
Sex: Female, Male Female	9 Participants n=23 Participants	12 Participants n=24 Participants	21 Participants n=47 Participants
Sex: Female, Male Male	14 Participants n=23 Participants	12 Participants n=24 Participants	26 Participants n=47 Participants
Race and Ethnicity Not Collected	—	—	0 Participants Race and Ethnicity were not collected from any participant.
Region of Enrollment United Kingdom	23 participants n=23 Participants	24 participants n=24 Participants	47 participants n=47 Participants

PRIMARY outcome

Timeframe: Patients will be examined 3 months post surgery.

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

Outcome measures

Outcome measures
Measure	Cementless Oxford Unicompartmental Knee Arthroplasty n=22 Participants Phase III Cementless Oxford Unicompartmental Knee Replacement (Biomet) Cementless Oxford Unicompartmental Knee Arthroplasty: 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.	Cemented Oxford Unicompartmental Knee Arthroplasty n=21 Participants Phase III Cemented Oxford Unicompartmental Knee Replacement (Biomet) Cemented Oxford Unicompartmental Knee Arthroplasty: 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 Femoral X Migration	-0.01 millimetres Standard Deviation 0.36	0.05 millimetres Standard Deviation 0.40
Radiostereometric Analysis Examination - Translations Femoral Y Migration	-0.10 millimetres Standard Deviation 0.34	-0.17 millimetres Standard Deviation 0.25
Radiostereometric Analysis Examination - Translations Femoral Z Migration	0.26 millimetres Standard Deviation 0.48	0.14 millimetres Standard Deviation 0.33
Radiostereometric Analysis Examination - Translations Tibial X Migration	-0.09 millimetres Standard Deviation 0.22	0.08 millimetres Standard Deviation 0.28
Radiostereometric Analysis Examination - Translations Tibial Y Migration	-0.23 millimetres Standard Deviation 0.18	-0.10 millimetres Standard Deviation 0.17
Radiostereometric Analysis Examination - Translations Tibial Z Migration	-0.03 millimetres Standard Deviation 0.20	-0.02 millimetres Standard Deviation 0.26

PRIMARY outcome

Timeframe: Patients will be examined 6 months post surgery.

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

Outcome measures

Outcome measures
Measure	Cementless Oxford Unicompartmental Knee Arthroplasty n=22 Participants Phase III Cementless Oxford Unicompartmental Knee Replacement (Biomet) Cementless Oxford Unicompartmental Knee Arthroplasty: 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.	Cemented Oxford Unicompartmental Knee Arthroplasty n=21 Participants Phase III Cemented Oxford Unicompartmental Knee Replacement (Biomet) Cemented Oxford Unicompartmental Knee Arthroplasty: 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 Femoral X Migration	-0.12 millimetres Standard Deviation 0.31	0.05 millimetres Standard Deviation 0.28
Radiostereometric Analysis Examination - Translations Femoral Y Migration	-0.02 millimetres Standard Deviation 0.39	-0.02 millimetres Standard Deviation 0.39
Radiostereometric Analysis Examination - Translations Femoral Z Migration	0.24 millimetres Standard Deviation 0.39	0.16 millimetres Standard Deviation 0.29
Radiostereometric Analysis Examination - Translations Tibial X Migration	0.06 millimetres Standard Deviation 0.19	0.06 millimetres Standard Deviation 0.19
Radiostereometric Analysis Examination - Translations Tibial Y Migration	-0.28 millimetres Standard Deviation 0.17	0.06 millimetres Standard Deviation 0.18
Radiostereometric Analysis Examination - Translations Tibial Z Migration	-0.03 millimetres Standard Deviation 0.13	-0.05 millimetres Standard Deviation 0.30

PRIMARY outcome

Timeframe: Patients will be examined 12 months post surgery.

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

Outcome measures

Outcome measures
Measure	Cementless Oxford Unicompartmental Knee Arthroplasty n=22 Participants Phase III Cementless Oxford Unicompartmental Knee Replacement (Biomet) Cementless Oxford Unicompartmental Knee Arthroplasty: 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.	Cemented Oxford Unicompartmental Knee Arthroplasty n=21 Participants Phase III Cemented Oxford Unicompartmental Knee Replacement (Biomet) Cemented Oxford Unicompartmental Knee Arthroplasty: 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 Femoral X Translation	-0.18 millimetres Standard Deviation 0.28	0.05 millimetres Standard Deviation 0.28
Radiostereometric Analysis Examination - Translations Femoral Y Translation	-0.12 millimetres Standard Deviation 0.24	-0.12 millimetres Standard Deviation 0.25
Radiostereometric Analysis Examination - Translations Femoral Z Translation	0.26 millimetres Standard Deviation 0.31	0.24 millimetres Standard Deviation 0.32
Radiostereometric Analysis Examination - Translations Tibial X Translation	-0.04 millimetres Standard Deviation 0.21	0.01 millimetres Standard Deviation 0.24
Radiostereometric Analysis Examination - Translations Tibial Y Translation	-0.28 millimetres Standard Deviation 0.19	-0.09 millimetres Standard Deviation 0.19
Radiostereometric Analysis Examination - Translations Tibial Z Translation	-0.01 millimetres Standard Deviation 0.15	0.00 millimetres Standard Deviation 0.26

PRIMARY outcome

Timeframe: Patients will be examined 24 months post surgery.

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

Outcome measures

Outcome measures
Measure	Cementless Oxford Unicompartmental Knee Arthroplasty n=22 Participants Phase III Cementless Oxford Unicompartmental Knee Replacement (Biomet) Cementless Oxford Unicompartmental Knee Arthroplasty: 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.	Cemented Oxford Unicompartmental Knee Arthroplasty n=21 Participants Phase III Cemented Oxford Unicompartmental Knee Replacement (Biomet) Cemented Oxford Unicompartmental Knee Arthroplasty: 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 Femoral X Translation	-0.05 millimetres Standard Deviation 0.53	0.03 millimetres Standard Deviation 0.34
Radiostereometric Analysis Examination - Translations Femoral Y Translation	-0.04 millimetres Standard Deviation 0.27	-0.05 millimetres Standard Deviation 0.32
Radiostereometric Analysis Examination - Translations Femoral Z Translation	0.21 millimetres Standard Deviation 0.23	0.22 millimetres Standard Deviation 0.42
Radiostereometric Analysis Examination - Translations Tibial X Translation	0.01 millimetres Standard Deviation 0.19	0.06 millimetres Standard Deviation 0.26
Radiostereometric Analysis Examination - Translations Tibial Y Translation	-0.34 millimetres Standard Deviation 0.23	-0.13 millimetres Standard Deviation 0.23
Radiostereometric Analysis Examination - Translations Tibial Z Translation	-0.02 millimetres Standard Deviation 0.16	0.03 millimetres Standard Deviation 0.22

PRIMARY outcome

Timeframe: Patients will be examined 60 months post surgery.

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.

Outcome measures

Outcome measures
Measure	Cementless Oxford Unicompartmental Knee Arthroplasty n=19 Participants Phase III Cementless Oxford Unicompartmental Knee Replacement (Biomet) Cementless Oxford Unicompartmental Knee Arthroplasty: 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.	Cemented Oxford Unicompartmental Knee Arthroplasty n=20 Participants Phase III Cemented Oxford Unicompartmental Knee Replacement (Biomet) Cemented Oxford Unicompartmental Knee Arthroplasty: 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 Tibial X Translation	-0.03 millimetres Standard Deviation 0.21	0.03 millimetres Standard Deviation 0.22
Radiostereometric Analysis Examination - Translations Femoral X Translation	-0.02 millimetres Standard Deviation 0.46	0.10 millimetres Standard Deviation 0.35
Radiostereometric Analysis Examination - Translations Femoral Y Translation	-0.07 millimetres Standard Deviation 0.29	-0.16 millimetres Standard Deviation 0.19
Radiostereometric Analysis Examination - Translations Femoral Z Translation	0.14 millimetres Standard Deviation 0.31	0.20 millimetres Standard Deviation 0.30
Radiostereometric Analysis Examination - Translations Tibial Y Translation	-0.28 millimetres Standard Deviation 0.19	-0.14 millimetres Standard Deviation 0.29
Radiostereometric Analysis Examination - Translations Tibial Z Translation	0.00 millimetres Standard Deviation 0.11	0.01 millimetres Standard Deviation 0.31

PRIMARY outcome

Timeframe: Patients will be examined 120 months post surgery.

Population: 1 Cemented Oxford Unicompartmental Knee Arthroplasty could not be analysed due poor quality stereoradiographs with obstruction of bone markers being obstructed. Consequently, although 15 Cemented Oxford Unicompartmental Knee Arthroplasties were followed-up at 120 months, only 14 could be analysed.

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

Outcome measures

Outcome measures
Measure	Cementless Oxford Unicompartmental Knee Arthroplasty n=16 Participants Phase III Cementless Oxford Unicompartmental Knee Replacement (Biomet) Cementless Oxford Unicompartmental Knee Arthroplasty: 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.	Cemented Oxford Unicompartmental Knee Arthroplasty n=14 Participants Phase III Cemented Oxford Unicompartmental Knee Replacement (Biomet) Cemented Oxford Unicompartmental Knee Arthroplasty: 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 Femoral X Translation	-0.12 millimetres Standard Deviation 0.50	0.24 millimetres Standard Deviation 0.31
Radiostereometric Analysis Examination - Translations Femoral Y Translation	-0.14 millimetres Standard Deviation 0.27	-0.16 millimetres Standard Deviation 0.21
Radiostereometric Analysis Examination - Translations Femoral Z Translation	0.20 millimetres Standard Deviation 0.36	0.14 millimetres Standard Deviation 0.28
Radiostereometric Analysis Examination - Translations Tibial X Translation	0.00 millimetres Standard Deviation 0.26	0.00 millimetres Standard Deviation 0.16
Radiostereometric Analysis Examination - Translations Tibial Y Translation	-0.29 millimetres Standard Deviation 0.20	-0.15 millimetres Standard Deviation 0.42
Radiostereometric Analysis Examination - Translations Tibial Z Translation	-0.01 millimetres Standard Deviation 0.21	0.02 millimetres Standard Deviation 0.23

PRIMARY outcome

Timeframe: Patients will be examined at 3 months post surgery.

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

Outcome measures

Outcome measures
Measure	Cementless Oxford Unicompartmental Knee Arthroplasty n=22 Participants Phase III Cementless Oxford Unicompartmental Knee Replacement (Biomet) Cementless Oxford Unicompartmental Knee Arthroplasty: 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.	Cemented Oxford Unicompartmental Knee Arthroplasty n=21 Participants Phase III Cemented Oxford Unicompartmental Knee Replacement (Biomet) Cemented Oxford Unicompartmental Knee Arthroplasty: 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 - Rotations Femoral X Rotation	0.22 Degrees Standard Deviation 0.95	0.19 Degrees Standard Deviation 0.47
Radiostereometric Analysis Examination - Rotations Femoral Y Rotation	0.26 Degrees Standard Deviation 0.55	0.10 Degrees Standard Deviation 0.74
Radiostereometric Analysis Examination - Rotations Femoral Z Rotation	-0.16 Degrees Standard Deviation 0.89	-0.10 Degrees Standard Deviation 0.95
Radiostereometric Analysis Examination - Rotations Tibial X Rotation	-0.48 Degrees Standard Deviation 0.88	-0.09 Degrees Standard Deviation 0.50
Radiostereometric Analysis Examination - Rotations Tibial Y Rotation	0.05 Degrees Standard Deviation 0.63	-0.08 Degrees Standard Deviation 0.46
Radiostereometric Analysis Examination - Rotations Tibial Z Rotation	0.36 Degrees Standard Deviation 0.70	-0.10 Degrees Standard Deviation 0.68

PRIMARY outcome

Timeframe: Patients will be examined at 6 months post surgery.

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

Outcome measures

Outcome measures
Measure	Cementless Oxford Unicompartmental Knee Arthroplasty n=22 Participants Phase III Cementless Oxford Unicompartmental Knee Replacement (Biomet) Cementless Oxford Unicompartmental Knee Arthroplasty: 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.	Cemented Oxford Unicompartmental Knee Arthroplasty n=21 Participants Phase III Cemented Oxford Unicompartmental Knee Replacement (Biomet) Cemented Oxford Unicompartmental Knee Arthroplasty: 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 - Rotations Femoral X Rotation	0.04 Degrees Standard Deviation 0.56	0.27 Degrees Standard Deviation 0.81
Radiostereometric Analysis Examination - Rotations Femoral Y Rotation	0.48 Degrees Standard Deviation 0.79	0.05 Degrees Standard Deviation 0.62
Radiostereometric Analysis Examination - Rotations Femoral Z Rotation	-0.11 Degrees Standard Deviation 0.90	0.19 Degrees Standard Deviation 0.76
Radiostereometric Analysis Examination - Rotations Tibial X Rotation	-0.46 Degrees Standard Deviation 0.78	-0.25 Degrees Standard Deviation 0.65
Radiostereometric Analysis Examination - Rotations Tibial Y Rotation	0.12 Degrees Standard Deviation 0.58	0.07 Degrees Standard Deviation 0.36
Radiostereometric Analysis Examination - Rotations Tibial Z Rotation	0.33 Degrees Standard Deviation 0.71	0.15 Degrees Standard Deviation 0.98

PRIMARY outcome

Timeframe: Patients will be examined at 12 months post surgery.

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

Outcome measures

Outcome measures
Measure	Cementless Oxford Unicompartmental Knee Arthroplasty n=22 Participants Phase III Cementless Oxford Unicompartmental Knee Replacement (Biomet) Cementless Oxford Unicompartmental Knee Arthroplasty: 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.	Cemented Oxford Unicompartmental Knee Arthroplasty n=21 Participants Phase III Cemented Oxford Unicompartmental Knee Replacement (Biomet) Cemented Oxford Unicompartmental Knee Arthroplasty: 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 - Rotations Femoral X Rotation	0.22 Degrees Standard Deviation 0.57	0.16 Degrees Standard Deviation 0.65
Radiostereometric Analysis Examination - Rotations Femoral Y Rotation	0.24 Degrees Standard Deviation 0.52	-0.05 Degrees Standard Deviation 0.63
Radiostereometric Analysis Examination - Rotations Femoral Z Rotation	-0.26 Degrees Standard Deviation 0.93	0.25 Degrees Standard Deviation 0.80
Radiostereometric Analysis Examination - Rotations Tibial X Rotation	-0.38 Degrees Standard Deviation 0.73	-0.10 Degrees Standard Deviation 0.70
Radiostereometric Analysis Examination - Rotations Tibial Y Rotation	0.16 Degrees Standard Deviation 0.54	-0.02 Degrees Standard Deviation 0.45
Radiostereometric Analysis Examination - Rotations Tibial Z Rotation	0.10 Degrees Standard Deviation 0.63	-0.29 Degrees Standard Deviation 0.67

PRIMARY outcome

Timeframe: Patients will be examined at 24 months post surgery.

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

Outcome measures

Outcome measures
Measure	Cementless Oxford Unicompartmental Knee Arthroplasty n=22 Participants Phase III Cementless Oxford Unicompartmental Knee Replacement (Biomet) Cementless Oxford Unicompartmental Knee Arthroplasty: 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.	Cemented Oxford Unicompartmental Knee Arthroplasty n=21 Participants Phase III Cemented Oxford Unicompartmental Knee Replacement (Biomet) Cemented Oxford Unicompartmental Knee Arthroplasty: 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 - Rotations Femoral X Migration	0.20 Degrees Standard Deviation 0.54	0.23 Degrees Standard Deviation 0.68
Radiostereometric Analysis Examination - Rotations Femoral Y Migration	0.23 Degrees Standard Deviation 0.52	0.32 Degrees Standard Deviation 0.52
Radiostereometric Analysis Examination - Rotations Femoral Z Migration	0.00 Degrees Standard Deviation 1.28	-0.06 Degrees Standard Deviation 0.75
Radiostereometric Analysis Examination - Rotations Tibial X Migration	-0.40 Degrees Standard Deviation 0.76	-0.17 Degrees Standard Deviation 0.69
Radiostereometric Analysis Examination - Rotations Tibial Y Migration	0.24 Degrees Standard Deviation 0.61	0.03 Degrees Standard Deviation 0.44
Radiostereometric Analysis Examination - Rotations Tibial Z Migration	-0.01 Degrees Standard Deviation 0.60	-0.31 Degrees Standard Deviation 0.68

PRIMARY outcome

Timeframe: Patients will be examined at 60 months post surgery.

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

Outcome measures

Outcome measures
Measure	Cementless Oxford Unicompartmental Knee Arthroplasty n=19 Participants Phase III Cementless Oxford Unicompartmental Knee Replacement (Biomet) Cementless Oxford Unicompartmental Knee Arthroplasty: 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.	Cemented Oxford Unicompartmental Knee Arthroplasty n=20 Participants Phase III Cemented Oxford Unicompartmental Knee Replacement (Biomet) Cemented Oxford Unicompartmental Knee Arthroplasty: 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 - Rotations Femoral X Rotation	0.35 Degrees Standard Deviation 0.44	0.16 Degrees Standard Deviation 0.54
Radiostereometric Analysis Examination - Rotations Femoral Y Rotation	0.29 Degrees Standard Deviation 0.79	-0.34 Degrees Standard Deviation 2.07
Radiostereometric Analysis Examination - Rotations Femoral Z Rotation	-0.17 Degrees Standard Deviation 1.14	0.25 Degrees Standard Deviation 0.88
Radiostereometric Analysis Examination - Rotations Tibial X Rotation	-0.28 Degrees Standard Deviation 0.80	-0.34 Degrees Standard Deviation 1.19
Radiostereometric Analysis Examination - Rotations Tibial Y Rotation	0.28 Degrees Standard Deviation 0.47	0.07 Degrees Standard Deviation 0.40
Radiostereometric Analysis Examination - Rotations Tibial Z Rotation	-0.13 Degrees Standard Deviation 0.68	-0.45 Degrees Standard Deviation 0.80

PRIMARY outcome

Timeframe: Patients will be examined at 120 months post surgery.

Population: 1 Cemented Oxford Unicompartmental Knee Arthroplasty could not be analysed due poor quality stereoradiographs with obstruction of bone markers being obstructed. Consequently, although 15 Cemented Oxford Unicompartmental Knee Arthroplasties were followed-up at 120 months, only 14 could be analysed.

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

Outcome measures

Outcome measures
Measure	Cementless Oxford Unicompartmental Knee Arthroplasty n=16 Participants Phase III Cementless Oxford Unicompartmental Knee Replacement (Biomet) Cementless Oxford Unicompartmental Knee Arthroplasty: 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.	Cemented Oxford Unicompartmental Knee Arthroplasty n=14 Participants Phase III Cemented Oxford Unicompartmental Knee Replacement (Biomet) Cemented Oxford Unicompartmental Knee Arthroplasty: 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 - Rotations Femoral X Rotation	-0.02 Degrees Standard Deviation 0.50	0.27 Degrees Standard Deviation 0.55
Radiostereometric Analysis Examination - Rotations Femoral Y Rotation	0.19 Degrees Standard Deviation 0.79	0.38 Degrees Standard Deviation 0.81
Radiostereometric Analysis Examination - Rotations Femoral Z Rotation	0.53 Degrees Standard Deviation 0.90	0.38 Degrees Standard Deviation 1.16
Radiostereometric Analysis Examination - Rotations Tibial X Rotation	-0.43 Degrees Standard Deviation 0.74	-0.66 Degrees Standard Deviation 2.59
Radiostereometric Analysis Examination - Rotations Tibial Y Rotation	0.18 Degrees Standard Deviation 0.48	0.15 Degrees Standard Deviation 0.36
Radiostereometric Analysis Examination - Rotations Tibial Z Rotation	-0.50 Degrees Standard Deviation 0.64	-0.79 Degrees Standard Deviation 1.14

PRIMARY outcome

Timeframe: Patients will be examined at 3 months post surgery.

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.

Outcome measures

Outcome measures
Measure	Cementless Oxford Unicompartmental Knee Arthroplasty n=22 Participants Phase III Cementless Oxford Unicompartmental Knee Replacement (Biomet) Cementless Oxford Unicompartmental Knee Arthroplasty: 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.	Cemented Oxford Unicompartmental Knee Arthroplasty n=21 Participants Phase III Cemented Oxford Unicompartmental Knee Replacement (Biomet) Cemented Oxford Unicompartmental Knee Arthroplasty: 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 - Maximum Total Point Motion Femoral MTPM	0.93 millimetres Standard Deviation 0.67	0.80 millimetres Standard Deviation 0.36
Radiostereometric Analysis Examination - Maximum Total Point Motion Tibial MTPM	0.84 millimetres Standard Deviation 0.45	0.61 millimetres Standard Deviation 0.40

PRIMARY outcome

Timeframe: Patients will be examined at 12 months post surgery.

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.

Outcome measures

Outcome measures
Measure	Cementless Oxford Unicompartmental Knee Arthroplasty n=22 Participants Phase III Cementless Oxford Unicompartmental Knee Replacement (Biomet) Cementless Oxford Unicompartmental Knee Arthroplasty: 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.	Cemented Oxford Unicompartmental Knee Arthroplasty n=21 Participants Phase III Cemented Oxford Unicompartmental Knee Replacement (Biomet) Cemented Oxford Unicompartmental Knee Arthroplasty: 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 - Maximum Total Point Motion Tibial MTPM	0.78 millimetres Standard Deviation 0.37	0.65 millimetres Standard Deviation 0.45
Radiostereometric Analysis Examination - Maximum Total Point Motion Femoral MTPM	0.76 millimetres Standard Deviation 0.35	0.80 millimetres Standard Deviation 0.53

PRIMARY outcome

Timeframe: Patients will be examined at 24 months post surgery.

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.

Outcome measures

Outcome measures
Measure	Cementless Oxford Unicompartmental Knee Arthroplasty n=22 Participants Phase III Cementless Oxford Unicompartmental Knee Replacement (Biomet) Cementless Oxford Unicompartmental Knee Arthroplasty: 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.	Cemented Oxford Unicompartmental Knee Arthroplasty n=21 Participants Phase III Cemented Oxford Unicompartmental Knee Replacement (Biomet) Cemented Oxford Unicompartmental Knee Arthroplasty: 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 - Maximum Total Point Motion Femoral MTPM	0.87 millimetres Standard Deviation 0.42	0.94 millimetres Standard Deviation 0.87
Radiostereometric Analysis Examination - Maximum Total Point Motion Tibial MTPM	0.84 millimetres Standard Deviation 0.39	0.64 millimetres Standard Deviation 0.51

PRIMARY outcome

Timeframe: Patients will be examined at 60 months post surgery.

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.

Outcome measures

Outcome measures
Measure	Cementless Oxford Unicompartmental Knee Arthroplasty n=19 Participants Phase III Cementless Oxford Unicompartmental Knee Replacement (Biomet) Cementless Oxford Unicompartmental Knee Arthroplasty: 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.	Cemented Oxford Unicompartmental Knee Arthroplasty n=20 Participants Phase III Cemented Oxford Unicompartmental Knee Replacement (Biomet) Cemented Oxford Unicompartmental Knee Arthroplasty: 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 - Maximum Total Point Motion Femoral MTPM	0.87 millimetres Standard Deviation 0.40	0.95 millimetres Standard Deviation 0.88
Radiostereometric Analysis Examination - Maximum Total Point Motion Tibial MTPM	0.79 millimetres Standard Deviation 0.30	0.80 millimetres Standard Deviation 0.68

PRIMARY outcome

Timeframe: Patients will be examined at 120 months post surgery.

Population: 1 Cemented Oxford Unicompartmental Knee Arthroplasty could not be analysed due poor quality stereoradiographs with obstruction of bone markers being obstructed. Consequently, although 15 Cemented Oxford Unicompartmental Knee Arthroplasties were followed-up at 120 months, only 14 could be analysed.

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.

Outcome measures

Outcome measures
Measure	Cementless Oxford Unicompartmental Knee Arthroplasty n=16 Participants Phase III Cementless Oxford Unicompartmental Knee Replacement (Biomet) Cementless Oxford Unicompartmental Knee Arthroplasty: 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.	Cemented Oxford Unicompartmental Knee Arthroplasty n=14 Participants Phase III Cemented Oxford Unicompartmental Knee Replacement (Biomet) Cemented Oxford Unicompartmental Knee Arthroplasty: 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 - Maximum Total Point Motion Femoral MTPM	0.98 millimetres Standard Deviation 0.41	0.84 millimetres Standard Deviation 0.41
Radiostereometric Analysis Examination - Maximum Total Point Motion Tibial MTPM	0.82 millimetres Standard Deviation 0.32	0.95 millimetres Standard Deviation 1.33

PRIMARY outcome

Timeframe: Patients will be examined at 12 months post surgery.

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'.

Outcome measures

Outcome measures
Measure	Cementless Oxford Unicompartmental Knee Arthroplasty n=22 Participants Phase III Cementless Oxford Unicompartmental Knee Replacement (Biomet) Cementless Oxford Unicompartmental Knee Arthroplasty: 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.	Cemented Oxford Unicompartmental Knee Arthroplasty n=21 Participants Phase III Cemented Oxford Unicompartmental Knee Replacement (Biomet) Cemented Oxford Unicompartmental Knee Arthroplasty: 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.
Radiographic Examination Tibial Component · Partial Radiolucency	7 Participants	11 Participants
Radiographic Examination Tibial Component · Complete Radiolucency	1 Participants	2 Participants
Radiographic Examination Tibial Component · No Radiolucency	14 Participants	8 Participants
Radiographic Examination Femoral Component · Partial Radiolucency	0 Participants	0 Participants
Radiographic Examination Femoral Component · Complete Radiolucency	0 Participants	0 Participants
Radiographic Examination Femoral Component · No Radiolucency	22 Participants	21 Participants

PRIMARY outcome

Timeframe: Patients will be examined at 24 months post surgery.

Population: Plain radiographs were only available for 21 of the 22 Cementless Oxford Unicompartmental Knee Arthroplasties at the 60 month timepoint, which explains the discrepency between the number of patients analyzed and the number of patients reported in the patient flow.

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'.

Outcome measures

Outcome measures
Measure	Cementless Oxford Unicompartmental Knee Arthroplasty n=21 Participants Phase III Cementless Oxford Unicompartmental Knee Replacement (Biomet) Cementless Oxford Unicompartmental Knee Arthroplasty: 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.	Cemented Oxford Unicompartmental Knee Arthroplasty n=21 Participants Phase III Cemented Oxford Unicompartmental Knee Replacement (Biomet) Cemented Oxford Unicompartmental Knee Arthroplasty: 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.
Radiographic Examination Femoral Component · No Radiolucency	21 Participants	21 Participants
Radiographic Examination Tibial Component · Partial Radiolucency	6 Participants	8 Participants
Radiographic Examination Tibial Component · Complate Radiolucency	0 Participants	5 Participants
Radiographic Examination Tibial Component · No Radiolucency	15 Participants	8 Participants
Radiographic Examination Femoral Component · Partial Radiolucency	0 Participants	0 Participants
Radiographic Examination Femoral Component · Complate Radiolucency	0 Participants	0 Participants

PRIMARY outcome

Timeframe: Patients will be examined at 60 months post surgery.

Population: Plain radiographs were only available for 18 of the 20 Cemented Oxford Unicompartmental Knee Arthroplasties at the 60 month timepoint, which explains the discrepency between the number of patients analyzed and the number of patients reported in the patient flow.

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'.

Outcome measures

Outcome measures
Measure	Cementless Oxford Unicompartmental Knee Arthroplasty n=19 Participants Phase III Cementless Oxford Unicompartmental Knee Replacement (Biomet) Cementless Oxford Unicompartmental Knee Arthroplasty: 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.	Cemented Oxford Unicompartmental Knee Arthroplasty n=18 Participants Phase III Cemented Oxford Unicompartmental Knee Replacement (Biomet) Cemented Oxford Unicompartmental Knee Arthroplasty: 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.
Radiographic Examination Tibial Component · Partial Radiolucency	1 Participants	6 Participants
Radiographic Examination Tibial Component · Complete Radiolucency	0 Participants	1 Participants
Radiographic Examination Tibial Component · No Radiolucency	18 Participants	11 Participants
Radiographic Examination Femoral Component · Partial Radiolucency	0 Participants	0 Participants
Radiographic Examination Femoral Component · Complete Radiolucency	0 Participants	0 Participants
Radiographic Examination Femoral Component · No Radiolucency	19 Participants	18 Participants

PRIMARY outcome

Timeframe: Patients will be examined at 120 months post surgery.

Population: Plain radiographs were only available for 15 of the 16 Cementless Oxford Unicompartmental Knee Arthroplasties and 14 of the 15 Cemented Oxford Unicompartmental Knee Arthroplastiesat the 60 month timepoint, which explains the discrepency between the number of patients analyzed and the number of patients reported in the patient flow.

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'.