LIGAMENT BALANCING IN PRIMARY TOTAL KNEE REPLACEMENT

James R. MacKenzie, BSc M.D, F.R.C.S.(C)

Clinical Lecturer,

Department of Surgery,

Faculty of Medicine, University of Calgary

Calgary, Alberta

Assessing the Results of Total Knee Replacement:

Pain

Function

Range of Motion

Stability

Deformity

Benefits to balancing the ligaments: optimize the results, recognize potential errors in bone resection and soft tissue problems intraoperative. It is essential to balance the ligaments if one is to use a mobile bearing type of knee.

Bony Alignment:

Varus, Valgus, Rotation, Translation, Flexion, Extension, Proximal, Distal

Lotke: “If we combine all of the possible malalignments we will note there are 11,684 methods to get it wrong and only one will have perfect alignment.”

Goals:

Confirm Tibial Cut Neutral

MCL = LCL

Flexion Gap = Extension Gap

Steps in TKA:

Tibial Resection

Distal Femur Resection

Femoral Antero-posterior Resection

Ligament Balancing

Femoral Finishing Cuts

Ligament Balancing Steps:

CHECK FLEXION SPACE

CHECK EXTENSION SPACE

CHECK ALIGNMENT OF TIBIAL CUT

RESOLVE DISCREPANCIES

Flexion Gap:

Soft Tissues (PCL)

Posterior Condyle Resection

Tibial Resection

Extension Gap:

Soft Tissues (Capsule, MCL, LCL)

Distal Femoral Resection

Tibial Resection

Flexion Gap is Tight:

Reassess the soft tissues (PCL).

Remove additional bone off the posterior femoral condyles (downsize the femoral component).

Extension Gap is Tight:

Reassess the soft tissues (Capsule, MCL).

Re-cut the distal femur.

Medial vs Lateral Imbalance:

Use an alignment rod to check the orientation of the proximal tibia cut prior to soft tissue releases.

Check the rotation of the posterior condyle resection cuts.

Conclusions:

Assessing soft tissue balance in the knee should be a standard step in performing a total knee. Results of TKA are likely to be better if this is done. It is an easy and quick procedure to help optimize your results. The few minutes you spend intraop will be far less than the time it takes to explain to the unhappy patient why their knee replacement is stiff or unstable.

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