Georg Matziolis1,2, Steffen Brodt3,4, Christoph Windisch3,4, Eric Roehner3,4. 1. Orthopedic Department, Friedrich-Schiller University, Campus Eisenberg, Jena, Germany. g.matziolis@krankenhaus-eisenberg.de. 2. Orthopedic Department, University Hospital Jena, Campus Eisenberg, Klosterlausnitzer Straße 81, 07607, Eisenberg, Germany. g.matziolis@krankenhaus-eisenberg.de. 3. Orthopedic Department, Friedrich-Schiller University, Campus Eisenberg, Jena, Germany. 4. Orthopedic Department, University Hospital Jena, Campus Eisenberg, Klosterlausnitzer Straße 81, 07607, Eisenberg, Germany.
Abstract
INTRODUCTION: There is no algorithm for the management of joint stability in midflexion up to now. Change in the joint line (JL) is considered to be the primary cause, although it only determines the extension gap. The purpose of this study was to determine the influence of the posterior condylar offsets (PCO), which defines the flexion gap, on midflexion instability. MATERIALS AND METHODS: Forty-two knee joints (38 patients) were included in this study, patients undergoing navigated total knee arthroplasty due to primary osteoarthritis of the knee. Changes in the JL and the PCO were determined from the navigation data. A gap tensioning device was used to determine the width of the joint gap at -5°, 0°, 30° and 60° intraoperatively. RESULTS: Within a range between 5 mm proximalization and 2 mm distalization, the JL had no influence on stability in midflexion. In contrast to this, both an increase and a decrease in PCO led to midflexion instability (R = 0.361, p = 0.019). In 16 cases (38%), the PCO was changed by more than 2 mm. This led to a midflexion instability of more than 2 mm in seven of these cases (44%). CONCLUSIONS: Whereas the joint line can be displaced by up to 5 mm without measurable changes in joint stability, reconstruction of the posterior offset within a tight range of 2 mm is necessary to avoid midflexion instability.
INTRODUCTION: There is no algorithm for the management of joint stability in midflexion up to now. Change in the joint line (JL) is considered to be the primary cause, although it only determines the extension gap. The purpose of this study was to determine the influence of the posterior condylar offsets (PCO), which defines the flexion gap, on midflexion instability. MATERIALS AND METHODS: Forty-two knee joints (38 patients) were included in this study, patients undergoing navigated total knee arthroplasty due to primary osteoarthritis of the knee. Changes in the JL and the PCO were determined from the navigation data. A gap tensioning device was used to determine the width of the joint gap at -5°, 0°, 30° and 60° intraoperatively. RESULTS: Within a range between 5 mm proximalization and 2 mm distalization, the JL had no influence on stability in midflexion. In contrast to this, both an increase and a decrease in PCO led to midflexion instability (R = 0.361, p = 0.019). In 16 cases (38%), the PCO was changed by more than 2 mm. This led to a midflexion instability of more than 2 mm in seven of these cases (44%). CONCLUSIONS: Whereas the joint line can be displaced by up to 5 mm without measurable changes in joint stability, reconstruction of the posterior offset within a tight range of 2 mm is necessary to avoid midflexion instability.
Entities:
Keywords:
Joint line; Midflexion instability; Posterior offset; Total knee arthroplasty
Authors: Bartosz M Maciąg; Artur Stolarczyk; Grzegorz J Maciąg; Monika Dorocińska; Piotr Stępiński; Jakub Szymczak; Maciej Świercz; Krystian Żarnovsky; Marcin Łapiński; Magda Stolarczyk Journal: Arthroplast Today Date: 2021-11-01