ORLANDO, Fla., USA — Most severe varus deformities in primary total knee arthroplasties can usually be adequately corrected without releasing the superficial medial collateral ligament, according to a presenter at the Current Concepts in Joint Replacement Winter Meeting, here.
Releasing the medial collateral ligament (MCL) during total knee arthroplasty (TKA) can have the unintended consequence of creating significant mediolateral instability and a flexion gap that may exceed the extension gap, according to Arun Mullaji, FRCS(ED), MS, of Mumbai, India.
“The take-home message is that most severe varus deformities can be corrected without releasing the superficial MCL, and therefore, we do not need to use constrained implants,” he said.
Five steps for soft-tissue balancing
Mullaji explained there are five key steps surgeons should use to achieve soft-tissue balance in cases of severe varus deformity without performing a superficial MCL release. The first step is to preoperatively determine whether the patient’s deformity is intra-articular or extra-articular. This can be done, he said, with full-length radiographs.
The second step is to individualize the valgus resection angle and bony resection depth. Surgeons should resect the bone growth on the tibia and femur, particularly if there is severe subluxation or recurvatum and the deformity angle exceeds 20°, he said.
“Then you need to balance the gaps, starting first with the extension gap, getting it balanced and rectangular, and then equalizing the flexion gap by adjusting the femoral component size and placement so that you now have a balanced gap,” Mullaji said.
Osteotomy may be required
Extra-articular deformities may require adjuvant procedures, particularly if the deformity exceeds 20° to 30° and is close to the knee, he said.
The third step is to complete a reduction osteotomy, posterolateral capsule resection, extra-articular corrective osteotomy or a sliding medial condylar osteotomy if necessary, he said. For example, if a patient has a mild extra-articular deformity, a reduction osteotomy should be performed.
“We remove the posterior medial flair of the tibia, and that relaxes the MCL and allows you to achieve correction. By removing 2 mm of bone, you can get about 1° of correction,” Mullaji said.
Surgeons must also compensate for bone loss and would rarely need to use a more constrained device, he said.
“Rarely do we have to use more constraining implants, as for example, in a patient with severe bone destruction and disorganization of the collateral frame. That is when we use a more constrained implant on both sides,” he said.
Address bone defects
The last step, according to Mullaji, is to address the bone defects in patients through performing a step-cut osteotomy and using local bone graft, particularly that taken from the notch.
In each TKA procedure for a patient with varus deformity, soft-tissue balancing can be achieved by following these five key steps, Mullaji noted – by Robert Linnehan
- Mullaji A. Paper #76. Presented at: Current Concepts in Joint Replacement Winter Meeting; Dec. 9-12, 2015; Orlando, Fla., USA.
- For more information:
- Arun Mullaji, FRCS(ED), MS, can be reached at The Arthritis Clinic, 101 Cornelian, Kemp’s Corner, Cumballa Hill, Mumbai 400036, India; email: email@example.com.
Disclosure: Mullaji reports he receives consulting fees for design and teaching from Zimmer Biomet and he receives royalties and consulting fees for design and teaching from DePuy Synthes.