Techniques of Oxford Partial Knee Replacement

1. Surgical Technique
of Oxford UKA
Prof. Rajesh Malhotra
All India Institute of Medical
Sciences, New Delhi, India

2. Key Points
• Identify Correct Indication
• Understand the Technique
• Plan Diligently
• Exposure
• Prepare Tibia
• Prepare Femur
• Cementing the Components

3. Indications
• Medial OA
–Other surfaces functionally intact
• Ligaments - All functionally normal
–Correctable varus deformity
–No medial or lateral subluxation
• Ligaments are never released
• Ligament balance achieved by
removing bone

4. Contraindications
• Varus > 15 degrees
• Flexion deformity > 15 degrees
• Deformity not passively correctable
• Inflammatory arthritis
• Stiff knee
–Must flex at least 110 degrees under anesthesia

5. Ligaments intact
• Antero-medial OA (White et al)
• No Posterior Tibial Bone Loss
Posterior
Posterior
Posterior
Anterior
Anterior Anterior

6. Normal Knee
Extension

7. Normal Knee
20º Flexion

8. Normal Knee

9. Varus deformity at 20º

10. 20º Flexion
Antero-medial OA
correctable varus

11. Extension
Extension - often impossible
Varus not correctable
Short posterior Capsule

12. Flexion - normal Cartilage

17. Incision
• In a 90˚ flexed knee
–a paramedial skin incision is made
from the medial margin of the
patella to a point 3 cm distal to the
joint line just medial to the tibial
tubercle
– The incision is deepened through
the joint capsule
–The capsular incision is extended
proximally for 1 to 2 cm into the
vastus medialis

18. INCISION OSTEOPHYTE REMOVAL

19. Inspection before proceding to
unicondylar replacement
• Inspection after arthrotomy in midflexion for the
status of
– the ACL
– the lateral compartment
– the patello-femoral joint
• Any intercondylar osteophytes can be removed from
the notch to prevent impingement on the ACL, and
patellar osteophytes can be debrided.
• Using a narrow chisel, osteophytes are removed
from beneath the medial collateral ligament and
from the posterolateral margin of the medial condyle

20. Osteophytes
• When removing osteophytes from the
posterolateral margin of the medial
condyle the chisel should be directed
towards the femoral head
• Small lesions on medial part of lateral
femoral condyle ("kissing osteophytes"-
developed as a result of impingement of
lateral tibial spine on the medial aspect of
lateral part of intercondylar notch) if
present are debrided, so is the small lesion
on medial patellar facet

22. Tibial preparation
Saw cut below
eburnated bone
7º slope
Stylus
7.5mm
Plateau and
bearing

23. TIBIAL PREPARATION
• Vertical cut crucial
• Ensure
• ACL is not injured
• Direction of cut important
• Point towards the femoral
head

24. TIBIAL PREPARATION

25. Tibial preparation
Measure gap
with feeler gauge
4mm or more,
if not recut
(3mm for small)
Tibial template

26. TIBIAL PREPARATION

29. FEMORAL PREPARATION

31. FEMORAL PREPARATION

35. Spherical
Cutter

39. Ligament balance
Flexion & extension
gaps remeasured
to confirm
ligament balance
If not balanced
calculate
additional bone
to be removed
and add to
spigot size

42. Fixed flexion deformity
Present at end of operation
Corrects with time
Posterior capsule short so fixed flexion

43. Coronal plane
Alignment
• Varus/valgus
depends on bearing
thickness
• Bearing restores
ligament tension
• Alignment restored
to pre-disease state

44. Coronal plane
alignment
• Normal alignment
Head

45. Coronal plane
alignment
• Normal alignment
• Medial Compartment OA
– Genu Varum, lax MCL

46. Coronal plane
alignment
• Normal alignment
• Medial Compartment OA
– Genu Varum, lax MCL
• Medial UKR
– MCL normal length
– Genu Varum corrected
• Normal alignment restored

47. Coronal alignment
• Normal alignment - varus
– Tibia Vara

48. Coronal alignment
• Normal alignment - varus
– Tibia Vara
• Medial Compartment OA
– Genu Varum, lax MCL

49. Coronal alignment
• Normal alignment - varus
– Tibia Vara
• Medial Compartment OA
– Genu Varum, lax MCL
• Medial UKR
– MCL normal length
– Genu Varum corrected
• Normal Varus restored
– Will not cause failure

50. Coronal plane
Alignment
• Does not depend
on component
alignment

51. Coronal plane
Alignment
• Does not depend
on component
alignment

52. Coronal plane
Alignment
• Does not depend
on component
alignment
• Components are
spherical. Minor
Mal-alignment is
not important

55. Removal of posterior femoral
osteophyte

59. Key points
• Ligaments normal - do not release
• Tibia resected until 3mm feeler gauge
and tibial plateau can be inserted
• Distal femur milled until ligaments are
balanced at 90° and 20°
• Component alignment not critical
• Accept FFD - will correct spontaneously