Ligament Balancing in TKA

• The basic aim is to get both extension and flexion gaps rectangular, equal and balanced. This balanced tension is important for implant stability and long-term survival.
• Two popular knee replacement techniques currently practiced are: “measured resection” which depends on tibial and femoral bone cuts through resection guide and “balanced resection” which depends on optimising ligament tensioning. Both affect ligament balancing during the operation.
• A stepwise approach for sequential ligament releases, according to the type of deformity, is essential to good outcomes.

Balancing Coronal Plane

Varus knee:

Medial side is tight and lateral side is loose.

Medial releases

1) Removal of osteophytes / Deep MCL release

2) Release posteromedial corner subperiostally

3) Medial tibial reduction osteotomy

4) Release semimembranous

5) Superficial MCL release

· Pie crusting technique

· Release anterior part if it is tight in flexion, posterior part if it is tight in extension

6) Complete superficial MCL release subperiosteally from the tibia.

· CCK / Constrained prosthesis has to be used.

Lateral tightening

· Use a thicker polietilen to fill up the gap and medial release to make the stretched lateral ligaments taut.

· Proximal fibula osteotomy and advancing it distally to tighten the LCL.

Valgus knee:

· Lateral femoral condyle is hypoplastic

· The distal femoral cut should be made less valgus (3ᵒ) to avoid residual valgus deformity.

· To avoid the distal femur cut in internal rotation, the trans-epicondylar axis should be referenced instead of the posterior condylar line.

Lateral releases (debatable)

· The lateral collateral ligament is a stabilizing structure in flexion and extension, and has rotational and varus stabilizing effects.

· The popliteus tendon complex also has passive varus stabilizing effects in flexion and extension, but has a more prominent role in external rotational stabilization of the tibia on the femur.

· The posterolateral corner has primary stabilizing effects in extension, but also is effective in flexion.

· The iliotibial band contributes to lateral knee stability when knee is extended, but when the knee is flexed to 90°, it is parallel to the joint surface, and cannot stabilize the knee to varus stress.

1) Removal of osteophytes

2) Posterolateral capsule

3) Iliotibial band (release must be performed only when contraction is present in extension.)

4) Popliteus tendon (if tight in flexion)

5) Lateral collateral ligament (stabilizing structure both in flexion and in extension.)

6) Lateral head of gastrocnemius muscle at femoral origin (if only tight in flexion)

Medial tightening

· Advance the MCL more proximally from the femoral origin with bone block

· Advance the MCL more distally from tibial side and fix it with staple or screw

· Suturing the MCL onto itself

Balancing Sagital Plane

· İf gap problem is symetric adjust tibia

Tibial cut affects both flexion and extension gap

· İf gap problem is asymetric adjust femur

Distal femoral cut affects extension gap

Posterior femoral cut affects flexion gap

Rotation of the femoral component influences the flexion gap balancing!

Posterior release order

1) Posterior femoral & tibial osteophytes

2) Posterior capsule

3) Additional resection of distal femur

4) Gastronemius muscles (medial and lateral)

The addition of a PCL release for a PS knee increases the flexion gap.

Treatment strategy for sagittal balance problem

1)Tight in extension and flexion

Problem

- Did not cut enough tibia

Solution

- Cut more proximal tibia

2)Loose in extension and flexion

Problem

- Cut too much tibia

Solution

1. Use thicker poly insert

2. Add metal augments to tibial tray

3)Tight in flexion / Balanced in extension

Common in CR / PCL tightness

- Limited flexion

- Anterior lift off of tibial tray

Problem:

- Insufficient posterior femoral cut

- Scarred and too tight PCL

- No posterior slope in tibial cut

Solution:

1. Resect posterior osteophytes / release posterior capsule

2. Release / excise PCL

3. Recut tibia with increased slope

4. Resection of more bone from the posterior condyle by reducing the size of the femoral component

4)Loose in flexion / Balanced in extension

Problem:

- Cut too much posterior femur

Solution:

1.Upsize femoral component

2.Recut distal femur, convert to symmetric gap problem and increase poly

5)Tight in extension / Balanced in flexion

Problem:

- Insufficient distal femoral cut

- Tight posterior capsule

Solution:

1. Release posterior capsule / osteophytes

2. Cut more distal femur

6)Loose in extension / Balance in flexion

Problem:
Cut too much distal femur.

Solution:
1) Augment distal femur

2) Downsize femur, convert to symmetric gap problem and increase poly

References

· Whiteside LA. New York: Springer; 2004. Ligament balancing in total knee arthroplasty: an instructional manual

· Babazadeh S, Stoney JD, Lim K, Choong PF. The relevance of ligament balancing in total knee arthroplasty: how important is it? A systematic review of the literature. Orthop Rev (Pavia). 2009 Oct 10;1(2):e26. doi: 10.4081/or.2009.e26. PMID: 21808688; PMCID: PMC3143981.

· Matsuda S, Ito H. Ligament balancing in total knee arthroplasty-Medial stabilizing technique. Asia Pac J Sports Med Arthrosc Rehabil Technol. 2015 Aug 7;2(4):108-113. doi: 10.1016/j.asmart.2015.07.002. PMID: 29264249; PMCID: PMC5730662.