Patellar Malalignment Combined With Deformed Valgus Knee Treated by Distal Femoral Varus Osteotomy and Retrograde Intramedullary Nailing.

OBJECTIVES: Patellar malalignment (PM) is common and a deformed valgus knee is an uncommon contributing factor. A deformed valgus knee can magnify the traction forces laterally during knee extension, consequently leading to PM. Treatment of combined disorders without correction of the deformed valgus knee is often less effective. The objective of this study was to assess the possibility of using the retrograde intramedullary nailing technique with some modifications for the treatment of both disorders. METHODS: From January 2011 to December 2020, 36 consecutive adult patients with 36 combined disorders underwent surgical treatment. The distal femur was obliquely osteotomized by creating a posterior cam on the distal bony fragment. The cam was consequently inserted into the marrow cavity of the proximal bony fragment. After the bone marrow was reamed, a dynamically locked intramedullary nail was inserted using the retrograde technique. A lateral retinacular release was performed on the patella, and the articular surfaces of the lateral patellar facet and lateral femoral condyle were drilled. The chi-square test was used to analyze categorical data and the Mann-Whitney U test was used to analyze numerical data. RESULTS: Thirty-two patients were followed for an average of 2.8 years (range, 1.7-5.4 years) and all osteotomized sites healed (average, 2.8 months). All 32 deformed valgus knees were corrected to the acceptable axis (from an average of valgus 10° initially to valgus 2° finally in 32 knees on the mechanical axis, p < 0.001). All PM had improved congruence angle, lateral patellofemoral angle, and patellofemoral index (p < 0.001 in all three). Both the tibiofemoral and patellofemoral joints achieved satisfactory function in all patients (p < 0.001). CONCLUSION: The described technique can concomitantly treat both the tibiofemoral and patellofemoral joints. Although the technique is relatively simple, the effect is remarkable, and the success rate is high. Therefore, it may be a valuable alternative for the treatment of combined disorders.