Speaker details extra-articular deformity correction for patients with varus, valgus knees
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Surgeons should consider computer-assisted surgery, adjuvant osteotomy and technique when planning for extra-articular deformity correction in patients with varus and valgus knees in total knee arthroplasty, a speaker said.
“Extra-articular deformity (EAD) is often seen,” Arun B. Mullaji, FRCS(Ed), MCh(Orth), MS(Orth), said in his presentation at the Current Concepts in Joint Replacement Meeting. “In fact, EAD is seen in 41% of varus knees – either in the tibia, in the femur or in both – and about one-third of valgus knees,” he added.
Mullaji detailed several surgeon and patient preferences that must be considered before planning EAD correction. The first step is to understand alignment, he said. Full-length X-rays are mandatory, and CT scans may be performed for rotational malalignment. He noted surgeons should consider soft tissue balancing and the use of computer-assisted surgery.
Determining static divergence angle (DA) is crucial in deciding between an intra-articular and extra-articular approach, Mullaji said. Most EAD corrections can be done with an intra-articular approach; however, if the angle between the planned resection lines is going to compromise collateral attachment or the distal tibial axis passes outside the plateau, an extra-articular approach is warranted, he noted.
When the dynamic DA is less than 10°, surgeons may perform a standard exposure, osteophyte excision or iliotibial band release for valgus deformity. For a DA between 10° and 15°, surgeons may consider a reduction osteotomy, capsular release or sliding epicondylar osteotomy. Lastly, for a DA of greater than 15°, surgeons need to do a closed-wedge osteotomy, Mullaji said.
“In summary, EAD requires careful planning. Most can be managed by intra-articular correction, [but] extra-articular correction is required if the deformity is more than 20° and close to the joint,” Mullaji said. “Navigation or patient-specific instrument [surgery] can be useful, and adjuvant osteotomy may sometimes be needed,” he concluded.