Radiographic Assessment of Total Knee Arthroplasty Alignment with and without Accelerometer-Based Navigation at a Resident Training Institution.

Introduction: Malalignment and lack of surgeon experience are cited as risk factors for prosthetic failure and the need for subsequent revision surgery in total knee arthroplasty (TKA). Various Conventional (CON) and Computer Assisted Surgical (CAS) methods have been developed to try and prevent malalignment and limit outliers. One of these methods is through an accelerometer-based CAS (aCAS) which intra-operatively helps determine the angulation and amount of resection necessary to restore alignment in TKA. The purpose of this study was to determine the number of TKA alignment outliers in TKA's performed both with CON and aCAS methods at a single training institution in cases that trainees were involved in.

Methods: In this retrospective single center study, radiographic analysis of 150 primary TKAs performed at our training institution was performed. The medial distal femoral angle (DFA), medial proximal tibial angle (PTA), and posterior slope angle (PSA) were evaluated on immediate post-operative radiographs of 75 aCAS and 75 CON knees. Outlier measurements were defined as DFA outside of 5° ±3° valgus; PTA >±3° from neutral axis; and PSA outside 0-7° for Cruciate Retaining (CR) and 0-5° for Posterior Stabilized (PS) implants. Data was analyzed using chi-squared, ANOVA and Student's t-tests.

Results: There was no significant difference found between these two groups in the total number of outliers (8% aCAS versus 9.8% CON, p=0.508). Additionally, there was also no significant difference found for any of the radiographic measurements independently; DFA (8% versus 8%, p=1.00), PTA (4% versus 9%, p=0.184), and PSA (12% versus 12%, p=1.00), when comparing aCAS and CON TKA's.

Conclusions: Primary TKAs performed at a single training institution demonstrated no significant difference between aCAS and CON methods in the total number of outliers or in the number of outliers for each postoperative radiographic measurement. This study would suggest that there is no advantage in limiting outliers when utilizing aCAS for TKAs at training institutions in cases that trainees are involved in.