Original article
The Variability of Intramedullary Alignment of the Femoral Component During Total Knee Arthroplasty

https://doi.org/10.1016/j.arth.2004.10.011Get rights and content

Abstract

Intramedullary instrumentation for femoral component alignment during total knee arthroplasty is readily used. Newer alignment techniques using computer navigation are now available. This study assesses the difference in the sagittal and coronal plane alignments using a cadaveric model with 3 different entry points for intramedullary alignment compared with a navigation system. Seven cadaveric limb's results show that the anterior starting point resulted in recurvatum (−2.2° ± 1.4° ), the middle starting point resulted in 1.9° ± 2.2° of flexion, and the posterior starting point in 3.8° ± 2.6° of flexion compared with the calculated femoral axis by the computer navigation system. When comparing the valgus angle, no statistical difference between any methods resulted (average 5.2° ± 0.9° valgus). The anterior and posterior starting points were significantly different in the sagittal plane. These data suggest that alignment can be significantly affected by the starting point chosen for intramedullary instrumentation.

Section snippets

Methods and Materials

Seven cadaveric lower extremities were used for the study in 4 cadaveric bodies. One lower extremity could not be used because of the existence of a previous total knee arthroplasty. For each lower extremity, a standard midline incision was made and medial third parapatellar approach to the knee used to attach anchoring pins in the femur and tibia for attachment of infrared emitters, per manufacturer's instructions (Stryker Navigation, Kalamazoo, Mich). A pelvic anchoring pin was also placed 2

Results

A significant difference in flexion of the intramedullary rod was recorded for the anterior and posterior starting points. The anterior starting point on average resulted in −2.2° ± 1.4° (representing recurvatum of the femoral component) compared with the mechanical axis, and the middle starting point resulted in 1.9° ± 2.2° of flexion compared with the calculated femoral mechanical axis by the computer-assisted surgery system (Fig. 2A). The posterior starting point resulted in 3.8° ± 2.6° of

Discussion

A misaligned primary TKA may result in an earlier than expected revision. The use of intramedullary alignment has greatly improved the coronal plane alignment of femoral components and helped to increase the long-term survival of a total knee arthroplasty. However, as the present study showed, the coronal plane is not the only one in which a femoral component alignment problem may occur.

Our data clearly demonstrate that entry point deviation of just 5 mm anteriorly or posteriorly may result in

References (13)

There are more references available in the full text version of this article.

Cited by (75)

  • Systematic effects of femoral component rotation and tibial slope on the medial and lateral tibiofemoral flexion gaps in total knee arthroplasty

    2020, Journal of Orthopaedic Translation
    Citation Excerpt :

    Arthroplasties are typically performed with the goal of reducing pain, correcting deformities and improving functionality, and outcomes are influenced by several factors, including sex, age, body weight, surgical indication, surgical technique, technical equipment and surgeon skills [3,4]. Moreover, the orientation of the prosthetic components plays a critical role in the lifetime of a prosthetic implant [5]. The poorer outcomes of knee arthroplasties compared with hip arthroplasties [6] are presumably related to the greater complexity of the anatomy and consequently the biomechanics of the knee compared to the hip.

View all citing articles on Scopus
View full text