A comparative assessment of knee alignment and functional outcomes in total knee arthroplasty with mid vastus approach via computer-based hand-held navigation and conventional methods

Background: Total knee arthroplasty has greatly benefitted by the use of computer-aided navigation approaches. The latest chapter in the use of computer-aided devices in TKA is the application of accelerometer-based hand-held devices. With several advantages offered by the accelerometer-based navigation system, it is a promising candidate for preferred modality for TKA. The aim of this study is to compare the clinical, functional and radiological outcomes of accelerometer-based and conventional navigational approaches.

Methods: We assessed a total of 68 arthroplasties for comparison of pre-operative and post-operative parameters. For pre-operative outcomes we compared operative time and loss of blood/hemoglobin. For the post-operative outcomes, we considered the radiological outcomes used to assess optimum alignment, and used interviewer-administered International Knee Society’s functional and clinical Knee Society Score (KSS) and patient reported pain measured on Visual Acuity Score (VAS). The assessment of functional and clinical KS scores and pain (through VAS) was done one- and two-years post-surgery.

Results: Operative time is significantly higher in Accelerometer-Based Navigation (ABN) as compared to conventional method (p<0.000). Accelerometer-based navigation achieves better alignment of the implant as compared to conventional navigation (p<0.000, 0.001 and 0.017 in SFA, STA and FCA respectively and p<0.000 for post-operative mechanical axis). Patient-reported pain was significantly lower in the ABN group at two-year follow up (p=0.019). Investigator-assessed clinical and functional knee scores were also significantly higher in ABN group at the final follow-up (p=0.002 and 0.003 for clinical and functional scores, respectively). The difference in the functional (p=0.035) and clinical (p=0.023) knee scores within the groups pre- and post-operatively was also found to have changed significantly in the ABN group as compared to conventional group during the two-year follow up.

Conclusion: Better alignment, reduced number of outliers in terms of malalignment, better functional and clinical scores and reduced pain two-year post-surgery demonstrate the advantage of ABN approaches over conventional navigation. The higher operative times along with higher cost associated with ABN approach are the factors which might limit the expanse of ABN as the modality of choice.