Total knee arthroplasty alignment strategies and their impact on ankle and hindfoot: a systematic review

Multiple alignment strategies have been proposed in total knee arthroplasty (TKA), ranging from systematic approaches such as mechanical alignment and anatomical alignment to personalized techniques including kinematic, restricted kinematic, inverse kinematic, and functional alignment. Although previous studies and reviews have evaluated the relationship between TKA and distal alignment, the influence of different knee alignment strategies on ankle and hindfoot alignment remains less clearly defined. The aim of this systematic review was to evaluate the impact of TKA alignment strategies on postoperative ankle and hindfoot alignment. A systematic review was conducted according to PRISMA guidelines. Medline (PubMed) and the Cochrane Library were searched for studies evaluating preoperative and postoperative ankle and/or hindfoot alignment following TKA. Eligible studies included clinical investigations reporting radiographic measurements of the ankle or hindfoot and clearly defining the TKA alignment strategy adopted. Study design, level of evidence, patient demographics, alignment technique, radiographic parameters, and functional outcomes were extracted and analyzed. Twenty-two studies were included, most of which provided level III evidence. Sixteen studies evaluated mechanically aligned TKA only, five compared mechanical alignment with personalized or alternative alignment strategies, and one investigated a personalized alignment strategy without direct comparison. Mechanical alignment consistently corrected coronal knee malalignment, particularly varus knee deformity, but distal ankle and hindfoot adaptations were variable. These changes appeared to be influenced by the severity of preoperative varus deformity, subtalar joint flexibility, and the presence of ankle osteoarthritis. Residual hindfoot valgus and incomplete distal compensation were frequently reported, especially in patients with severe preoperative varus knee deformity. Mechanical alignment reliably corrects coronal knee alignment, but ankle and hindfoot responses are variable and may remain incomplete in patients with severe varus deformity, ankle osteoarthritis, or limited subtalar compensation. Selected studies suggest that personalized alignment strategies may reduce compensatory distal changes, but the available evidence is limited and heterogeneous. Further comparative studies with standardized ankle and hindfoot assessment are needed before firm conclusions can be drawn.