Limb Lengthening after Primary Total Knee Arthroplasty:Customized Patient-Specific Instrumentation Does Not AffectExpected Limb Lengthening

Expectations for limb length differences after TKA are important for patient perception and outcomes. Limb lengthdiscrepancies may occur due to postoperative leg length increases, which can lead to decreased patient functionality and sat-isfaction and even possible litigation. 'e purpose of this study is to examine the frequency and extent of limb lengthening amongvarious preoperative deformities and between two different implant systems.Methods. Preoperative and postoperative full-lengthstanding radiographs were obtained between August 2018 and August 2019 to measure mechanical axis and limb length ofoperative limbs. Demographic information such as age, sex, and BMI was also collected. Patients were grouped into categories forpre- and postoperative subgroup analysis: valgus, varus, customized implant, and conventional implant. Regression analysis wasperformed to evaluate significant relationships.Results. Of the 121 primary TKAs analyzed, 62% of the knees showed an increasein limb length after TKA, with an average lengthening of 5.32 mm. Preoperative varus alignment was associated with a meanlengthening of 3.14 mm, while preoperative valgus alignment was associated with a mean lengthening of 16.2 mm. Overall, therewere no statistically significant differences in limb lengths pre- and postoperatively (p�0.23) and no significant changes in limblength for any subgroup. Further, no variables were associated with limb length changes (p�0.49), including the use of cus-tomized implants (p�0.2).Conclusions. Limb lengthening after TKA is common and, on average, occurs more significantly invalgus knees. No significant difference in limb lengthening could be demonstrated using customized over conventional implants.Preoperative counseling is important to manage patient expectations.