Comparison of an Accelerometer-Based Portable Navigation System, Patient-Specific Instrumentation, and Conventional Instrumentation for Femoral Alignment in Total Knee Arthroplasty

PURPOSE: The KneeAlign2 (KA2, OrthoAlign Inc.) accelerometer-based portable navigation system and patient-specific instrumentation (PSI; Signature, ZimmerBiomet) are widely used for ideal femoral component alignment in total knee arthroplasty (TKA). However, there has been no comparative study of the KA2 system, PSI, and conventional intramedullary instrumentation (CON). The purpose of this study was to compare the accuracy in achieving proper femoral component alignment and clinical features by using the KA2 navigation system, PSI, and CON. MATERIALS AND METHODS: We retrospectively compared the accuracy of femoral component alignment of 34 TKAs performed with the KA2 system for implantation of the femoral component, 32 TKAs with PSI, and 33 TKAs with CON. RESULTS: In the coronal plane, use of the KA2 system was more likely to result in optimal femoral component alignment than the CON and PSI (p < 0.01). In the sagittal plane, use of the KA2 system was more likely to result in optimal component alignment than PSI, but the difference between the KA2 and CON was insignificant. CONCLUSIONS: The portable accelerometer-based KA2 navigation system enabled ideal femoral implantation in the coronal and sagittal planes, as compared to the PSI or CON.

Lateral Knee Pain after Outside-in Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction Using the TightRope RT

The anterior cruciate ligament (ACL) TightRope RT (TR) was recently introduced as a novel cortical suspension device for ACL reconstruction. It has an adjustable graft loop that gives the surgeon some advantages during ACL reconstruction. We report three patients who required removal of the TR after an outside-in anatomical ACL reconstruction because of lateral knee pain. We assumed that the knee pain was associated with friction between the TR button of the posterolateral bundle and iliotibial band (ITB). Placing the TR button close to the lateral epicondyle and tissue interposition between the TR button and lateral femoral cortex may be potential risk factors for ITB irritation. Therefore, we recommend not placing the TR button close to the top of the lateral epicondyle and reducing the tissue interposition between the TR button and lateral femoral cortex as much as possible.