Preoperative Malalignment Increases Risk of Failure After Total Knee Arthroplasty Merrill A. Ritter, MD; Kenneth E. Davis, MS; Peter Davis, BA; Alex Farris, BA; Robert A. Malinzak, MD; Michael E. Berend, MD; John B. Meding, MD J Bone Joint Surg Am. 2013;95(2): doi: /JBJS.K Authors: Affiliation: Center for Hip and Knee Surgery, St. Francis Hospital, Mooresville, Indiana Journal Club Cheng Chen 05/13

Purpose: To analyze the effect of preoperative knee alignment on implant survival after TKA Methods: Retrospective review Time span: Sept – Nov Sample size: 5342 TKAs in 3699 patients (2242 women and 1457 men) Ave. age: 70.2 yo (range, 21-92) Ave. patient BMI: 30.0 kg/m 2 (range, ) Ave. duration of follow-up: 7.1 yrs (range, ) Preoperative diagnosis: OA(95.3%), RA(3.3%), other(1.4%) Prosthesis: Anatomic Graduated Components (Biomet) Malalignment: Pre OP (>8 o of varus OR >11 o of valgus) Post OP( 7.4 o of valgus)

Results:

Statistics: PreOP malalignment knees had 4.3 times the risk of failure than preOP neutrally alignmented knees; 54 of 5342(1%) knees failed, 26(48.1%) were caused by tibial collapse, 16(29.6%) by ligamentous Instability, 7(13%) by femoral component failure, and 5(9.3%) by radiolucency; 3151 knees were neutrally aligned both preOP and postOP and had a failure rate of 0.51% ; For the 635 corrected knees, the failure rate was 1.9% ; For the 365 knees that were undercorrected, uncorrected, or overcorrected, the failure rate was 3.0%.

Conclusions: 1)Patients with preOP malalignment have a greater risk of failure 2)Neutral postOP alignment improves but does not eliminate the risk of failure 3) Careful attention should be paid in TKA for patients with severe preoperative deformities

Limitation of the study: Demographic characteristics such as age, sex, BMI etc were not included in this study.