Review Question - QID 219761

Patients with valgus deformity are at increased risk of post-operative peroneal palsy compared to those with varus alignment secondary to lengthening of the lateral aspect of the knee with subsequent traction on the nerve.

Evaluating coronal knee alignment is a critical step in total knee arthroplasty. A valgus deformity presents a unique set of challenges that must be addressed to achieve deformity correction and restoration of mechanical alignment. Valgus deformities regularly involve contracted lateral capsular and ligamentous structures with accompanying medial laxity. Bony deficiency is common and typically involves the lateral femoral condyle or the lateral tibial plateau. This makes it difficult to determine the epicondylar axis and can lead to internal rotation of the femoral component with subsequent abnormal patellar tracking. Several complications are more likely to occur in valgus patients, including instability, recurrent valgus, wound breakdown, incorrect patellar tracking, and peroneal nerve palsies.

Krackow et al. evaluated 81 patients with a significant valgus deformity that required specific soft tissue releases during TKA. They report a classification system to delineate between valgus subtypes; type I represents deformity secondary to bone loss in the lateral compartment and soft-tissue contracture with medial soft tissues intact; Type II was defined as obvious attenuation of the medial capsular ligament complex; and Type III was defined as severe valgus deformity with valgus malpositioning of the proximal tibial joint line after overcorrected proximal tibial osteotomy. They demonstrate near-identical outcomes between Type I and Type II patients and conclude that lateral release in Type I and medial plication in Type II are satisfactory methods to address balance and alignment.

Ranawat et al. report their series of 490 consecutive patients treated with an inside-out technique involving posterior capsule release and pie-crusting of the iliotibial band. At the final 5-year follow-up, they demonstrate significant improvements in coronal alignment, Knee Society scores, and range of motion among all patients (35 total). The authors conclude that this “inside-out” release is reproducible and leads to excellent long-term results.

Figure A demonstrates a preoperative x-ray with mild valgus deformity Figure C shows a preoperative x-ray with varus deformity.

Incorrect answers:
Answer 2: A valgus deformity is more likely to fail into recurrent valgus, not varus.
Answers 3-5. Patients undergoing TKA with valgus deformity have not been shown to have increased revision surgery, PJI, or prolonged hospitalization.