1. Total Knee Arthroplasty
Dr. Rami Eid
06/06/2006

2. Introduction
TKA is one of the most successful and commonly performed orthopedic surgery.
The best results for TKA at 10 – 15 yrs. compare to or surpass the best result of THA.

3. Indications for Knee Arthroplasty

4. Indications for TKA
Relieve pain caused by osteoarthritis of the knee (the most common).
Deformity in patients with variable levels of pain:
Flexion contracture > 20 degrees.
Severe varus or valgus laxity.

5. Osteoarthritis
American College of Rheumatology classification criteria:
Knee pain and radiographic osteophytes and at least 1 of the following 3 items:
Age >50 years.
Morning stiffness <=30 minutes in duration.
Crepitus on motion.

6. Contraindications for TKA
Recent or current knee sepsis.
Remote source of ongoing infection.
Extensor mechanism discontinuity or severe dysfunction.
Painless, well functioning knee arthrodesis.
Poor health or systemic diseases (relative contraindications).

7. Unicondylar Knee Arthroplasty
Indications:
Younger patients with unicompartmental disease instead of HTO.
Elderly thin patient with unicompartmental disease (shorter rehabilitation, greater ROM)
Contraindications:
Flexion contracture >= 5 degrees.
ROM < 90 degrees.
Angular deformity >= 15 degrees.
Cartilaginous erosion in the weight-bearing area of the opposite compartment.

8. Patellar Resurfacing Indication for leaving the patella unresurfaced:
Congruent patellofemoral tracking.
Normal anatomical patellar shape.
No evidence of crystalline or inflammatory arthropathy.
Lighter patient.

9. Classification

10. Classification 1 3 1- Cruciate retaining 2- Cruciate substituting
3- Mobile bearing
4- Unicondylar 2 4

11. Biomechanics of Knee Arthroplasty

12. Kinematics The TRIAXIAL motion of the knee: Articular geometry
Ligamentous restraints

13. Degrees of Freedom

14. Degrees of Freedom Constrained Prostheses Non-constrained Prostheses
Intermediated Prostheses

15. Constrained Prostheses
Hinged implants.
One degree of freedom.

16. Non-constrained Prostheses
Ideal implants.
5 degrees of freedom.
Intact ligamentous system.

17. Intermediated Prostheses
Anterior-posterior stability.
Two types:
FREEMAN (a cylinder in a non conforming trough).
INSALL (posterior stabilized knee).

18. Intermediated Prostheses
Freeman
Insall

19. Longitudinal Alignment Of Knee
Tibial components are implanted perpendicular to the mechanical axis.
Femoral component is implanted in 5 – 6 degrees of valgus.

20. Longitudinal Alignment Of Knee
Posterior tibial tilt is about 5 – 7 degrees.
Usually depend on the articular design.
Anatomic tilt 5 degrees

21. Rotational Alignment Of Knee
Create a rectangular flexion space.
External rotation of the femoral component 3 degrees.

22. Role of PCL – Femoral Roll-Back

23. Role of PCL – Femoral Roll-Back

24. PCL-retention or PCL-substitution ?
PCL retaining prostheses:
Better ROM (roll-back, flat tibial surface).
More symmetrical gait (stair climbing).
Less femoral bone resection is required.
PCL needs to be accuracy balanced.
PCL substituting prostheses:
Easier surgical exposure.
See-saw effect prevention.
Lower tibial polyethylene contact stress
Posterior tibial component displacement.
Patella clunk syndrome.

25. PCL-retention or PCL-substitution ?

26. PCL-retention or PCL-substitution ?

27. Patella Clunk Syndrome

28. Patellofemoral Joint The patella acts to lengthen extensor lever arm.
This arm is greatest at 20 degrees of flexion.

29. Patellofemoral Joint
Changes in the patellar area of contact can leads to eccentric loading of the patellofemoral joint.

30. Patellofemoral Joint
Limb with larger Q angle has a greater tendency for lateral subluxation.
Preventing subluxation:
Prosthetic component.
Vastus medialis (in early flexion).

31. Polyethylene Issues
1- Dished polyethylene avoids the edge loading. (as PCL substitution)
2- Minimal polyethylene thickness >= 8 mm to avoid higher contact stress.

32. Surgical Technique for Primary TKA

33. Preoperative Evaluation
Soft tissue defects around the knee.
Vascular status to the limb.
Extensor mechanism.
Preoperative range of motion.
Standing (AP) view, a lateral view of the knee, and a skyline view of the patella.

34. Surgical Preparation
Administer a dose of a 1st generation cephalosporin (or vancomycin, clindamycin)
Avoid pressure on peripheral nerves.

35. Surgical Approaches Medial parapatellar retinacular approach.
Subvastus approach.
Midvastus approach.

36. Surgical Approaches Subvastus approach: Midvastus approach:
Intact extensor mechanism.
Decreasing pain.
More limited.
Postoperative hematoma.
Midvastus approach:
Preserve genicular a. to the patella.
Contraindication in limited preoperative flexion.
Postoperative hematoma.

37. Surgical Approaches Lateral parapatellar retinacular approach:
In valgus knees.
Improve patellar tracking and ligamentous balancing.

38. Bone Preparation – IM Femoral Guide

39. Bone Preparation – Gap Technique

40. Bone Preparation – Tibial Resection
The guide is aligned with the anterior tibial tendon and first web space of the toes.

41. Balancing of The Knee

42. Varus Deformity 1st Osteophytes must be removed.
2nd Release the deep MCL.
3rd Release semimembranosus and pes anserinus insertion.
4th release posterior capsule and PCL.

43. Varus Deformity

44. Valgus Deformity 1st Remove all osteophytes.
2nd release lateral capsule.
3rd
Lesser deformity: release Iliotibial band.
Greater deformity: release LCL +/- PCL.
Valgus deformity + flexion contracture >> release posterior capsule.

45. Valgus Deformity

46. Flexion Contracture
Extension gap < Flexion gap >> more distal femoral bone cut, posterior capsule release.
Flexion gap < Extension gap >> larger tibial insert.

47. Flexion – Extension Balancing

48. Computer Assisted Surgery in Total Knee Arthroplasty

53. Management of Bone Deficiency

56. Patellofemoral Tracking
Internal rotation of tibial component increases the tendency to lateral patellar subluxation.
Prosthetic patella should be medially positioned.

57. Postoperative Management

58. Roentgenographic Evaluation

59. Total knee replacement exercise protocol
Postoperative day 1
Bedside exercises (e.g. ankle pumps, quadriceps exercises…)
Postoperative day 2
Exercises for active ROM and terminal knee extension
Gait training with assistive device
Postoperative day 3-5
Progression of ambulation on level surfaces and stairs (if applicable)
Postoperative day 5 to 4 weeks
Stretching of quadriceps and hamstring muscles
Progression of ambulation distance

60. Specific Disorders

61. Previous HTO Difficult surgical exposure. Lateral ligamentous laxity.
Difficult stem placement.
Patella infera.

62. Previous Patellectomy
PCL retaining arthroplasty for better results.

63. Complications of Total Knee Arthroplasty
Thromboembolism.
Infection.
Neurovascular complications.
Patellofemoral complications.
Periprosthetic fractures.

64. Patellofemoral Complications
Patella clunk syndrome.
Patellar component failure.
Rupture of patellar ligament.

65. Periprosthetic Fractures

66. THANK YOU

67. MoKazem.com
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Dr. Muayad Kadhim
د. مؤيد كاظم