2015 ISAKOS Biennial Congress ePoster #1440

Comparisons of Kinematics During Stair Motion in Single-Radius Total Knee Arthroplasty: Cruciate Retaining vs. Substituting Designs

Yuichiro Kii, Sapporo, Hokkaido JAPAN
Tetsuya Tomita, MD, PhD, Suita, Osaka JAPAN
Takaharu Yamazaki, PhD, Suita, Osaka JAPAN
Keiji Iwamoto, MD, PhD, Osaka, Osaka JAPAN
Kazuma Futai, MD, PhD, Suita, Osaka JAPAN
Toshihiko Yamashita, MD, PhD, Sapporo, Hokkaido JAPAN
Hideki Yoshikawa, MD, PhD, Suita, Osaka JAPAN
Kazuomi Sugamoto, MD, PhD, Suita, Osaka JAPAN

Department of Orthopaedic Biomaterial Science, Osaka University Graduate School of Medicine, Suita, Osaka, JAPAN

FDA Status Not Applicable

Summary: We investigated the kinematics of the stair ascending and descending after single-radius TKA and to compare CR TKA and CS TKA and CR TKA is similar kinematic pattern with CS TKA.

Rate:

Abstract:

Purpose

This study investigated the kinematics of the stair ascending and descending after single-radius TKA and to compare cruciate retaining (CR) and cruciate substituting (CS) TKA.

Methods

We analyzed 16 knees (CR 8, CS 8) with a clinically successful single-radius TKA (Stryker Triathlon). Under fluoroscopic surveillance, each patient performed stair ascending and descending. Motion between each component was analyzed using a two- to three-dimensional registration technique, which uses computer-assisted design models to reproduce the spatial positions of the femoral and tibial components from single-view fluoroscopic images. We determined the images of the ground touch of the TKA leg on the ?rst step and selected the following four phases: 1) at foot strike (FS) (non-weight-bearing), 2) during stance phase before crossleg motion (full weight-bearing), 3) during stance phase after crossleg motion (still weight-bearing), and 4) at foot off (FO) (non-weight-bearing) We evaluated the knee flexion angle and anteroposterior translation of the femorotibial contact point for both the medial and lateral sides of the knee.

Results

During stair ascending, the mean flexion angle at foot strike was 65.2°±6.9° in CR knees and 60.8±4.5°in CS knees. Knees were gradually extended from foot strike to foot off. The mean flexion angle at foot off was 10.1°±4.6°in CR knees and 7.5±7.7°in CS knees. The medial contact point was 2.5±2.5 mm in CR and 4.1±1.8 mm in CS at foot strike and then it moved 4.6±2.3 mm posterior in CR and 4.5±1.9 mm posterior in CS while shifting weight to the leg. Similarly, the lateral contact point was -5.2±2.3 mm in CR and -4.2±2.2 mm in CS at foot strike and then it moved 1.8±2.2 mm posterior in CR and -4.3±2.2 mm posterior in CS while shifting weight to the leg. During stair descending, the mean flexion angle at foot strike was 9.1°±4.3°in CR knees and 8.6±4.3°in CS knees. Knees were gradually flexed from foot strike to foot off. The mean flexion angle at foot off was 40.5°±7.2° in CR knees and 37.3±6.6°in CS knees. The medial contact point was -4.2±3.0 mm in CR and -3.1±1.3mm in CS at foot strike, -4.2±1.5 mm in CR and -3.6±1.9mm in CS at stance phase before crossleg motion. The lateral contact point was -7.5±3.0mm in CR and -8.6±2.6mm in CS at foot strike and -7.6±2.2mm in CR and -9.6±1.7mm in CS at stance phase before crossleg motion. There is no significant difference between the positions at foot strike and at stance phase before crossleg in both knees.

Discussion

CR TKA is similar kinematic pattern with CS TKA during stair motion. The main reason for this is the anterior high lip of CS TKA substituting for PCL.