soft tissue balancing in primary total knee arthroplasty

1. Soft Tissue Balancing
In Primary TKR
By
Ihab El-Desouky (M.D.)
Asst. Prof. Pelvis and Reconstruction unit

2. Definitions
• Equalizing the forces of deformity around the knee during
TKRto allow for a functioning joint in a stable non-
deformed position joint in stance and moving
situations.
• A measure of the RELATIVE TENSIONS in the
soft tissue restraints over the full ROM
• The soft tissues about the knee should be considered
“balanced” when they are “appropriately tensioned” to
provide stability to the knee without causing stiffness,
limited motion, or pain

3. Topics
1- Anatomy of stabilizing structures (static &dynamic)
2-Biomechanics (kinematics) of knee stabilizers. (Native & OA)
3-Principles of soft tissue balancing:
-Exposure
-Measured resection.
-Femoral preparation
-Tibial preparation
-Gap technique.
4-Coronal plane deformities and management (varus &valgus)
5-Sagittal plane deformities and management (flexion deformity
&recurvatum)
6-Patello-femoral articulation.
7-Case presentation. (Polio)

4. Anatomy of knee stabilizers:
• Knee: bi-condyler joint (depends on stabilizers).
1-Dynamic stabilizers (lateral and medial)
2-Static stabilizers (lateral and medial)
3-Cruciate ligaments
4-Extensor mechanism.

5. Anatomy of knee stabilizers:
1-Dynamic Stabilizers:
Tendons of muscles:
Medial :
Semi-membranosus?,
semi-tendinosus,
gracilis,
sartorius ,Med Gastrocnemius
Vastus Medialis Obliquus (VMO)

6. Anatomy of knee stabilizers:
1-Dynamic Stabilizers:
Lateral:
Popliteus tendon complex
(arcuate lig. (PFL) is static)
Ilio-tibial band
Biceps femoris
Lat Gastrocnemius +
fabelo-fibular ligament
Vastus lateralis

7. Anatomy of knee stabilizers:

8. Anatomy of knee stabilizers:
2-Static Stabilizers: Ligaments (lig)
Lateral:
Lateral (fibular) collateral lig.(LCL)
Polpliteo-fibular lig.
Postero-lateral capsule.

9. Anatomy of knee stabilizers:
2-Static stabilizers:
Medial:
-Medial collateral lig. (MCL)
(super > deep)
Superficial: Ant & Post portions
Medial patello-femoral lig.
Posterior oblique lig. (POL)

10. Anatomy of knee stabilizers
Posterior Oblique lig.(POL)
Fibrous extension from
Semi-membra to inforce
postero medial capsule
-three arms (supericial
, capsular& tibial largest)

11. Anatomy of knee stabilizers
3-Cruciate ligaments:
Anterior cruciate:
in bi-compartmental OA
torn or will be torn
Posterior cruciate (PCL):
retained in PC retaining
Relation to menisci
-1ry stabilizer in Sagittal plane.
-PCL & Post. Capsule are 2ry stabilizers
In Both Varus and Valgus (after lig release)

12. Anatomy of knee stabilizers
4-Extensor mechanism:
Patello-femoral articulation
Quadriceps muscle and tendons
Patellar retinacula
(tense with knee flexion
to support patella in groove)

13. Kinematics of knee stabilizers
1-Kinematics of Native knee
Axes :
-Mechanical axis (centres Hip,Knee Ankle)
-Diff femoral mechanical &anatomical =
5-7 valgus (valgus cut angle)
-Tibial axes (mechanical &anatomical) are
collinear

14. Kinematics of knee stabilizers
1-Kinematics of Native knee
Joint Line:
In Extension: 3 ⁰ medial slope.
Tibial resection: perpendicular to
axes= valgus to native articular
surface
Femoral resection: perpendicular
to mechanical axis= varus to articular
surface

15. Kinematics of knee stabilizers
1-Kinematics of Native knee
In Flexion: femoral and tibial resection
Surfaces are
Parallel to trans-epicondylar axis (TEA)
And Perpendicular to antero-posterior
(Whiteside line) (A/P axis)

16. Kinematics of knee stabilizers
Knee Stabilizers:
Stabilizers around TEA tight in Both Ext and Flex
Stabilizers away from TEA tight only in Ext OR Flex
Lat side:
Extended
LCL, Postero-lateral capsule
Popliteus tendon, Ilio-tibial tract
Lat Gastrocnemius head, P/L corner

17. Kinematics of knee stabilizers
Lat Side: In Flex
LCL, Popliteus tendon
P/L corner (ilio-tibial tract is lax)
Med Side:
In Ext:
MCL superficial (post part) & deep
POL (posterior oblique lig)
Pes anserinus and semimembranosus
Posterior capsule

18. Kinematics of knee stabilizers
Med Side:
In Flex:
-MCL : deep +superficial (sMCL) anterior
-PCL tight in flexion For both varus and
valgus
-Posterior capsule and semimembranosus -- lax
So sMCL:
Ant portion: tight in Flex
Post portion: tight in ext (PE)

19. Kinematics of knee stabilizers
In OA: (osteophytes)
MCL: irritation with motion
--inflammation—tightness.
PCL—irritation—tightness
Lateral side: Popliteus tendon
complex irritation (not the LCL)

20. Kinematics of knee stabilizers
Screw Home mechanism

21. Principles of soft tissue balancing
• A soft tissue balanced joint
• have EQUAL & RECTANGULAR gaps between
the resected bone surfaces in extension and
flexion ---- equal tension in the medial and
lateral soft tissues
without changing
the anatomical joint line

22. Principles of soft tissue balancing
Techniques: Three (according to femoral rotation determination)
(3 ⁰ Extenal rotation)
1-Measured Resection: femoral cut by fixed bone
landmarks.
2-Gap Balancing: soft tissue tensioning after tibial
cut & femoral cut accordingly
3-Combination of both.!!

23. Principles of soft tissue balancing
1-Measured resection technique:
Exposure-Osteophytes resection.
Define bony landmarks: 3⁰ Ext rotation
-Parallel to Surgical TEA (tip to sulcus)
-Perpendicular to Whiteside line.(A/P)
-Parallel to resected tibial surface
-3⁰ext rotation to post condyle (PCA)
----Grand Piano Sign

24. Principles of soft tissue balancing
Then : ligament release if needed.
BUT
-Difficult identification of
Surgical TEA up to 30%.
-Hypoplastic trochlear sulcus & medial OA –more ext rot--
coronal instability in flexion & Condylar Lift-Off
-Hypoplastic femoral condyle (valgus knee) errors with PCA
SO: Difficult identification of bony landmarks
intraoperatively---improper balance ----flexion gap
asymmetry
and condylar lift-off and Wear acceleration

25. Principles of soft tissue balancing
2-Gap Balancing technique: (Freeman et al , 1984)
Exposure-Osteophytes resection, tibial cut---
Ligament release before femoral bone cuts
Sequence: (position of 1st lig tensioning)
1-Flexion Gap first (Gap Technique):
Tibial cut– Flexion of the knee and tensioning the
ligaments.

26. Principles of soft tissue balancing
Insert tensor assess femur:
-Parallel (TEA) +perpendicular (AP) axis
OK
If not-- ligament release then
femoral ant + post cuts
--Measure Gap
Extend knee and tensioning the lig.
Symmetric to gap in flexion. OK
If not—lig release.
Once gaps are symmetric
Insert cutting jigs and
complete distal femoral cut

27. 2-Extension gap first (modified gap technique)
More precise.
-Femoral distal cut (5-7⁰ valgus cut)
-Tibial cut
-Removal of Posterior osteophytes
(tibial & femoral)
-Extend knee- insert spacer block
Release tight ligs
Measure gap
Principles of soft tissue balancing

28. Principles of soft tissue balancing
2-Extension gap first (modified gap technique)
-Then flex knee
-Two laminar spreader to
tension lig
-Tibial cut –parallel to TEA
Perpend to A/P
-If symmetrical and equal to ext, insert
Cutting jig and Femur Ant and post cuts
(parallel to tibial surface)
-If Not—Lig release and cut

29. Principles of soft tissue balancing
2-Gap Balancing techniques:
Adv.: 1-Better rectangular gaps (then measured
resection)
2-Less flexion instability and condylar lift-
off 3-Less wear acceleration.
BUT: tibial cut is very critical
-Varus tibial cut--- internal rotation of femoral
cut and vise versa.
-Lig tensioning (blocks –spreader) needs
experience

30. Principles of soft tissue balancing
3-Combined Technique:
Exposure- osteophytes resection.
-Distal femoral resection (5-7⁰ valgus)---tibial resection.
-Extension gap assessment (spacer block) and Lig. Release
-Ant and post femoral cuts (3⁰ Ext rot- TEA) independent
to tibia
-Flexion gap assessment. ( spacer blocks & laminar
spreader) and lig release.
-Distal femoral cut: affects balancing in Extension
-Post Femoral cut: affects balancing in Flexion
Tibial cut : affects balancing in BOTH

31. Coronal Balancing in Primary TKA
(varus & valgus)
Principles: In Arthritic knee;
-Medial and lateral stabilizers
may be stretched or contracted with time.
-In concave side of deformity:
ligs are tight and need release.
-In convex side: ligs are stretched and
need tightening.
-Should be balanced in both extension and flexion
LET’S GO

32. Varus Knee
1-Etiology
2/3 of patients requiring TKR
have varus deformity. About 75% need medial release.
Causes:
OA, Inflammatory arthritis (rheumatoid !?valgus), gout
and pseudgout, ostreo-chondromatosis, intra-
articular fractures and failed previous HTO

33. Varus Knee
Pathology:
-Femoral condyles: little affection
-Tibial condyles: eroded medial plateau.
-Mechanical axis titled medial
to tibial axis (extended knee) and A/P axis (flexed knee)
-Osteophytes deform MCL and post capsule --Flexion contracture

34. Varus knee
Pathology:
-Tight popliteus tendon complex (osteophytes)
-Lateral subluxation of tibia
-MCL and PCL are contracted.
Evaluation:
Clinical:
Degree of deformity, (correctable),
ROM (flexion contracture)
, muscle strength, and
condition of the soft tissue envelope

35. Varus Knee
Evaluation:
Radiographic:
Weight bearing (A/P & Lat) in mild deformities.
Full-length standing A/P view in severe deformities,
Detect:
-Degree of deformity: Mild (< 15⁰), moderate (15-30 ⁰) &
severe (>30 ⁰)
-Magnitude of tibial defect and need for augmentation
(intra-operative is larger)
-Posterior osteophytes and flexion contracture.
-Templating: sizing and extent of medial
osteophytes (down-sizing)?? Stress fracture

36. Varus knee
Classification:
(2016) Site of angulation
Intra-Articular (IA):
Anteromedial-Posteromedial-
Fixed with lateral laxity & fixed without laxity
Metaphyseal: within 5cm
below joint-Big osteophytes
Diaphyseal:
More than 5 cm

37. Varus knee
Steps of correction: (Posterior Stabilized knee)
-Exposure:
-Medial para-patellar arthrotomy
-In Ext: Sup-periosteal release of medial sleeve
(capsule and deep MCL) for 3 cm
-In Flex & Ex rot: continue to P/M corner
(tibial metaphyseal flare)
Excision of the osteophytes
(tibial &femoral) –remember posterior osteophytes

38. Varus knee
Excision of PCL
Bony Resection (cuts)
-Distal femur : 5-7⁰ in short obese angle of 5⁰
-Proximal tibia (10 mm from intact lateral side)

39. Varus knee
Spacer Block in extension and assess:
If tight --- flex knee
release semimembranosus &
P/M capsule
Including POL (behind sMCL)
Till Rectangular gap
Bony resection:
Ant & Post femoral cuts (3⁰ Ext Rot)
(Bony landmarks TEA)

40. Varus knee
-Remove Posterior of osteophytes
-Insert Trial Components and assess:
Varus (in flexion and extension)
Rotation.
Stability (anterior and posterior)

41. Varus knee
Scenarios:
1- Balanced ( extension and flexion):
-Full extension & in 90⁰ flexion up to 2-3 mm medial opening.
(normal laxity)+ stable anterior lift-off test (drawer)
2-Tight Flexion +balanced extension
Medial tibial condyle protrusion but good extension
--Tight anterior Superficial MCL---Release in flexion

42. Varus knee
3-Tight in extension+ balanced in flexion
Limited full extension (contracture)---tight posterior sMCL+ post
capsule
Release in flexion
Directed 45 ⁰ to preserve anterior fibers
Posterior capsular release

43. Varus knee
4-Tight in flexion and extension:
Extension: lateral gapping with limited range
Flexion: medial tibial protrusion + lateral gap
Alternatives: ( ready for Constrained prosthesis !!)
1= Complete release of ant & post SMCL (up to 15
Cm from joint line)
2=Pie-crusting the sMCL:
Multiple punctures of the
Lig till lateral gap closed
OR

44. Varus knee
3-Downsize the tibial component:
& tibial part is lateralized
To give functional lengthening of MCL

45. Varus knee

46. Valgus knee
Etiology:
10 -15 % of cases for TKR
Causes
OA then,
Rheumatoid arthritis, post-traumatic , osteonecrosis of
lateral femoral condyle, metabolic bone disease (renal
osteodystrophy) & overcorrection of HTO

47. Valgus knee
Pathology:
-< 10 ⁰ tibiofemoral angle
-Femoral part: hypoplastic lateral
condyle (distal and posterior)
-Tibial part: little affection but; external
rotation, displaced tibial tubercle.
-Patella: increased Q angle with mal-tracking
and even dislocation

48. Valgus Knee
Pathology:
Lateral stabilizer: contracted.
MCL stretched or incompetent.
Early are reducible then fixed.
Evaluation:
Clinical: ROM, fixed or reducible, patellar
position (!dislocated), & associated skeletal
lesions.

49. Valgus Knee
Evaluation:
Radiographic: -Weight-bearing A/P
Full –length X-ray deformity angle
-Stress views to assess reducibility
-Lateral view: patellar position,
tibial slope
-Skyline view: patellar dislocation
and arthritis

50. Valgus Knee
Classification: Ranawat 2005
I-Minimal + reducible deformity (stretched MCL)
angle < 10 ⁰ = 80 % of cases
II-Reducible deformity angle of 10-25⁰
attenuated MCL still functional = 15% of cases
III-Fixed deformity angle
> 25 ⁰
MCL defective= 5% of cases
(constrained TKR)

51. Valgus knee
-Steps of correction: Bony Correction Then Soft Tissue Balancing
-Lateral knee stabilizers 2 groups
At lat epicondyle (LCL, popliteus tendon ) :
tight in both flexion & extension)
Away from lat epicondyle:
(Ilio-tibial band, posterolateral capsule, biceps, and lateral
gastrocnemius )
Tight only in extension

52. Valgus Knee
Exposure: Anterior midline incision +
Grade I & II : medial para-patellar arthrotomy
Grade III: lateral para-patellar arthrotomy??
- Direct access to the lateral retinacular and capsular
ligamentous tissues for release.
- No disruption of the medial blood supply to the
patella with lateral release
BUT
-Limited medial exposure that needs wafer tibial tubercle osteotomy (?non-
union)
-After complete release, defective soft tissue coverage of the prosthesis
(transfer of adipose tissue of the fat pad!!)

53. Valgus Knee
After medial arthrotomy
Minimal sub-periosteal dissection of the capsule
and deep MCL + osteophytes excision
Bony Correction:
Tibial cut:
with extra-medullary guide
Less bone than usual
6-8 mm
from the unaffected medial side

54. Valgus Knee
Bony Correction:
Femoral cuts:
-Intrameduallry guide slightly
medial to centre of groove.
-Resting on medial condyle
-Valgus angle : 3 ⁰ ( -- MCL Strain,
prevent recurrence)
-Amount: 10mm from med condyle +
0-2 mm from lat condyle (augmentation)

55. Valgus Knee
Bony Correction:
Femoral cuts:
-A/P (Whiteside) axis is used
for rotation ( 3⁰ external)
-Ligaments are still tight
and tibia in valgus position.

56. Valgus Knee
Ligament Balancing:
Flexion and Extension balancing are independent
1-Extension balancing: (Inside –out)
Insert 2 laminar spreader and
-Pie crusting P/L
capsule + Iliotibial tract
(less than 1cm) Peroneal nerve
If not released:
Pie-crusting the LCL itself

57. Valgus knee
-LCL pie-crusting
Use laminar spreader to stretch the lateral side.
-If not balanced:
LCL + Popliteus tendon are
sharply detached from the lateral femoral condyle
(lateral epicondylectomy)
If not balanced
release of lat gastrocnemius

58. Valgus knee
2-Tight in flexion:
Pie crusting the popliteus tendon (not start by
LCL) then
LCL & posterolateral corner then
Lateral epicondylectomy.
3-Tight in Both: (enough)
Popliteus tendon and LCL then
Lateral epicondylectomy.

59. Valgus knee
Choice of implant:
If no laxity after release: PS Knee
If much laxity : (tibial insert more than 15 is needed)
Constrained condylar implant (avoid P. nerve stretch and Patella
baja)

60. Valgus Knee
Treatment Algorithm
- Medial approach+ Lat release
+ PS knee
-Medial approach + Lat release
If tight in Flexion: LCL, popliteus + PLC
If tight in both : LCL , popliteus
+PS or Constrained condylar knee (CCK)
-Lateral approach + Tibial tuber ost.
+ release as Grade II + CCK

61. Sagittal balancing in primary TKR
Flexion contracture:
Inability to fully extend the knee after insertion of
trials.
TTT:With knee in flexion:
-Remove posterior osteophytes.
-Release post capsule.
-Check PCL complete release
-Increase distal femoral cut
(not tibia --- patella alta)
-Gastrocnemius release (Med & Lat)
Other scenarios

62. Sagittal plane balancing
Symmetric gaps – address tibia
Asymmetric gaps – address femur
Femur: Distal femoral cut –controls extension
Posterior femoral cut controls flexion
Scenarios:

63. Sagittal plane balancing

64. Sagittal plane balancing

71. Case Presentaion
-56 male patient with polio affection of both LL
-Rt hip is dislocated with shortened flail limb
-Lt hip is stable but the Lt knee is deviated in
severe recurvatum and valgum on walking.
-Weak quadriceps muscle (0-1).
-Patient developed continuous pain of the Lt
knee (functioning limb) that prevent him from
sleep and attending his regular work

72. Case presentation
Problems: Severe OA with
- Single functioning limb.
- Dual ligamentous deficiency.
- Massive deformity.
(no posterior tension)
- No active extension
- Defective knee locking)
X-ray: (supine)

73. Case presentation
Solutions:
-Dual Ligamentous deficiency: Rotating Hinge Knee
-No locking of knee –keep joint in
slight recurvatum
-Weak soft tissue envelop—delayed
weight bearing
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