Soft Tissue and Gap Balancing in Revision TKA
At ICJR’s Pan Pacific Orthopaedic Congress in July, Dr. S.K.S. Marya offered pointers on improving stability in a revision TKA. Below is the abstract of his presentation, including a matrix to assist with decision-making.
By S.K.S.Marya, MBBS, MS, DNB, MCS, FRCS, FICS
Instability is the most common aseptic cause of revision knee replacement. The source of this instability can be straightforward or multifactorial. It is important to identify the reason for instability before embarking on a revision surgery.
Evaluating the patient clinically before and while under anesthesia prior to the operation, in combination with the intraoperative findings, enables the surgeon to identify any imbalances in the soft tissues
This is important, as the principles in a revision total knee arthroplasty (TKA) are similar to those of primary TKA: achieve a balanced, stable knee with optimal function by restoration of the joint line and soft tissue balancing.
The importance of achieving equal flexion and extension gaps cannot be overemphasized. Basic principles for gap balancing include the following:
- Distal femoral resection or augmentation affects only the extension gap,
- Femoral downsizing affects only the flexion gap
- Proximal tibial resection or increasing tibial insert thickness affects the flexion and extension gaps symmetrically
If there is irreconcilable mismatch between a capacious flexion gap and a less-accommodating extension gap, the use of a prosthesis with constraint is necessary to avoid instability.
The following matrix provides a ready reference to assist with decision-making when balancing the soft tissues and gaps in a revision TKA.
S.K.S.Marya, MBBS, MS, DNB, MCS, FRCS, FICS, is Chairman of the Max Institute of Musculoskeletal Sciences, located in Delhi and Gurgaon, India.