Reading X ray after Total knee arthroplasty is an art. Certain points that one should focus on are discussed here along with x rays

1. How to read Postoperative X- ray
after Total Knee Arthroplasty
DR. LOKESH CHUGH
SENIOR RESIDENT
DEPT. OF ORTHOPAEDICS
GMC, AMRITSAR.

2. AIMS OF TKR
• NEUTRAL MECHANICAL AXIS
• RESTORATION OF JOINT LINE
• PAINLESS MOBILE AND STABLE
JOINT

3. LONG FILM X RAY- SCANOGRAM
• IDEAL
• MECHANICAL AXIS
• Not always available
• Costly

4. SHORT FILM X- RAY AFTER TKR
Is it ok!!

5. CORONAL PLANE ALIGNMENT
• PARALLEL MEDIAL LATERAL JOINT LINE

6. CORONAL PLANE ALIGNMENT
• MEDIAL DISTAL FEMORAL
ANGLE = 95 DEGREE
• MEDIAL PROXIMAL TIBIAL
ANGLE = 90 DEGREE

7. CORONAL PLANE ALIGNMENT
• FFC 2-7 DEGREE
VALGUS
• FTC <3 DEGREE
VARUS

8. RESTORING JOINT LINE
• 23 MM FROM
LATERAL FEMORAL
EPICONDYLE
• 28 MM FROM
MEDIAL FEMORAL
EPICONDYLE
• 15 MM FROM
FIBULAR HEAD

9. RESTORING JOINT LINE
• EASY IN PRIMARY
• DIFFICULT IN REVISION
• DIFFICULT TO LOCALISE
• MALE AND FEMALE VARIATIONS

10. ADDUCTOR TUBERCLE JOINT LINE
• ONE CONSTANT
LANDMARK
• DEPENDENT ON FEMORAL
CONDYLAR WIDTH
• RATIO= ATJL/FW=0.52

11. RESTORING JOINT LINE IN REVISION
TKR
• MEASURE FEMORAL
CONDYLAR WIDTH
• MULTIPLY WITH 0.52,
CALCULATE ATJL
• DISTAL FEMORAL CUTTING
BLOCK FIXED AT ATJL AFTER
PUTTING INTRAMEDULLARY
JIG
• ASSESS AND SELECT
APPROPRIATE SIZE OF
AUGMENT

12. FEMORAL COMPONENT
• OVER HANG- NOT
DESIRED
• MEDIAL
OVERHANG- NO
• APPROPRIATE SIZE

13. FEMORAL COMPONENT
• APPROPRIATE SIZE
• NO NOTCHING
• SHENTON’S LINE
INTACT
• POSTERIOR
CONDYLAR OFFSET

14. FEMORAL COMPONENT- ALIGNMENT
• NEUTRAL
• NO FLEXION
• NO EXTENSION

15. POSTERIOR CONDYLAR OFFSET
• POSTERIOR
CONDYLAR OFFSET
=AB
• PCO RATIO = AB/AC

16. FEW WORDS ABOUT FEMORAL
NOTCHING – GUJARATHI GRADING
• GRADE 1 – OUTER
TABLE OF ANTERIOR
CORTEX
• GRADE 2 – OUTER
AND INNER TABLE
OF ANTERIOR
CORTEX

17. FEMORAL NOTCHING –
GUJARATHI GRADING
• GRADE 3-violation
of upto 25% of
medullary canal
• GRADE 4-violation
of upto 50% of
medullary canal

18. FEMORAL COMPONENT- CR/ PS
• POSTERIOR STABILISED
• BONE LOSS/CUT
• CAM AND POST NOT
VISIBLE ON X RAY

19. FEMORAL COMPONENT- CR
• CRUCIATE RETAINING
• NO BONE CUT
• ONLY PEGS FOR FIXATION
• NO BOX IN FEMORAL
COMPONENT

20. FEMORAL COMPONENT
• CEMENTATION CEMENTATION

21. TIBIAL COMPONENT
• OVER HANG
• MEDIAL OVERHANG -
NO
• IN CASE NEEDED LATERAL -
ACCEPTABLE
NO MEDIAL
OVERHANG

22. TIBIA COMPONENT
• SIZE- APPROPRIATE
• NO POSTERIOR
OVERHANG

23. POSTERIOR TIBIAL SLOPE
• 5 DEGREE
• No posterior
overhang

24. CEMENTATION

25. PATELLA – SKYLINE VIEW
• Skyline view- patellar
thickness
• Patellar tracking
M L

26. INSALL SALVATI RATIO
• PATELLAR TENDON/
PATELLAR LENGTH
• NORMAL = 0.8 – 1.2

27. PATELLA BAJA
• INSALL SALVATI RATIO
< 0.8
• Contracted patellar
tendon.

28. Instability of patellofemoral joint
• Skyline view-
patella in
trochlear groove
• Patellar tilt more
than 5 degree-
patellofemoral
instability

29. ASEPTIC LOOSENING
Radiological evaluation-SCORING
• 1-2 medial plateau
• 3-4 lateral plateau
• 5-7 stem fixation

30. ASEPTIC LOOSENING
Radiological evaluation-SCORING
• Lateral view- FEMORAL
SIDE
• 1-2 anterior flange
• 3-4 posterior area
• 5-7 stem or central portion

31. ASEPTIC LOOSENING
Radiological evaluation-SCORING
• Skyline view of patella
• 1 medial side
• 2 lateral side
• 3-5 fixation lugs (central)

32. INTERPRETATION FROM
RADIOLOGICAL EVALUATION

33. Risk factors of Heterotropic
Ossification
• Pre existing HO
• Hypertrophic OA
• Ankylosing spondylitis
• DISH
• Surgical factors- splitting
quadriceps tendon, striping
of soft tissue on anterior
aspect femur

34. Heterotropic ossification
• 1- upto 5 cm2
• 2- more than 5cm2
• 3- 2+near femur, restricts
knee flexion, needs surgery
• visible on x ray after 5
weeks.

35. Risk factor for fracture periprosthetic
fracture
• Osteopenia
• Osteolysis. PE wear
• Component loosening
• Anterior femoral notching
• Malalignment