Tips on Ligament Releases in TKA
In the abstract of his presentation at ICJR’s Pan Pacific Orthopaedic Congress, Dr. Norman Scott addresses the timing of ligament releases in total knee arthroplasty, as well as the involved ligaments in a varus or valgus deformity.
By W. Norman Scott, MD, FACS
Managing the arthritic knee is the polar opposite of managing the sports knee. With the sports knee, orthopaedic surgeons tighten loose ligaments and often use grafts to treat injuries. With the arthritic knee, that treatment strategy is not appropriate.
The reason is two-fold:
- An arthritic knee is more likely to involve bone than the sports knee.
- An arthritic knee is characterized by contracture of the ligaments, not the stretching seen in the sports knee.
To manage an arthritic knee, ligament releases and bone deformity must be addressed simultaneously in a total knee arthroplasty. The timing of the ligament release depends on the surgeon’s philosophy of gap balancing versus measured resection:
- In gap balancing, the releases are done prior to the bone resection.With measured resection techniques, the releases are performed after the bone resection.
- In the common hybrid techniques of gap balancing and measured resection, the releases are performed after the flexion/extension gaps and after femoral bone sizing and rotational alignment are achieved.
- In non-conventional surgical techniques, such as computer-assisted surgery, the use of patient-specific instruments, and robotic-assisted surgery, the releases are usually done after bone resection.
Ligament releases should create a knee that is stable in extension and is not in varus or valgus.
Releases in varus deformity are somewhat easier than release in valgus deformity. In the varus knee, the contracted medial structures include:
- Joint capsule
- MCL (superficial and deep)
- Semi-membranosus ligament
- Pes anserinus ligament
Unlike in the early history of releases, these structures are released in a sequential fashion.
In the valgus knee, the contracted structures include:
- Iliotibial band
- Lateral joint capsule
- Lateral collateral ligament
Posterior capsule release is done after the bone resection in a patient with a valgus knee. In rare instances, the distal femur may have to be recut. If so, it is done after the posterior capsule release.
In summary, the author’s preference is to release the ligaments after bone resection and to titrate the releases so that the ligaments are not over-released. The deformity must always be corrected as well – the surgeon should not walk out of the OR until that is done.
Dr. Scott’s presentation can be found here.
W. Normal Scott, MD, FACS, is from the Insall Scott Kelly Institute for Orthopaedics & Sports Medicine New York, New York.