Gait analysis in ankle osteoarthritis and total ankle replacement

Abstract

Background

Little information is available about gait changes in ankle osteoarthritis and total ankle replacement, and also about total ankle replacement patients’ rehabilitation in the first year after surgery.

Methods

Thirty subjects were included in this study: 15 unilateral post-traumatic ankle osteoarthritis patients and 15 age-/gender-matched control subjects. Patients were followed prospectively: preoperatively, at 3, 6, 9, and 12 months after total ankle replacement. The clinical-functional level was assessed by the American Orthopaedic Foot and Ankle Society ankle and the Short-Form-36 health survey score. 3D ankle-hindfoot kinematic–kinetic analysis was performed using a motion analysis and a two-plate force–platform system. Statistics included repeated measures analysis of variances, independent sample and paired Student’s t-tests (significance α = 0.05).

Findings

Compared to normal subjects, ankle osteoarthritis caused significant reduction of the American Orthopaedic Foot and Ankle Society and Short-Form-36 score. In gait analysis, ankle osteoarthritis showed a significant deficiency in six of seven spatiotemporal variables, a decrease of the tri-planar ankle movement, a decrease of the second active maximal vertical and the maximal medial ground reaction force, a reduction of the sagittal and transverse ankle joint moments, a reduction of the ankle joint power. Three months after total ankle replacement surgery patients experienced a worsening of gait. At 12 months follow-up, all spatiotemporal variables were not different from the normal subjects (full rehabilitation); in six of 11 kinematic and kinetic variables there was a partial rehabilitation.

Interpretation

This study provides data for the clinical-biomechanical understanding of the normal, arthritic, and total ankle replacement treated ankle during walking and the first year of rehabilitation.

Introduction

Ankle osteoarthritis (OA) is a progressive cartilage degenerative disease and is characterized by pain, a reduced range of motion, loss of quality of life, general disability, and other invaliding symptoms (Agel et al., 2005, Thomas and Daniels, 2003). In over 70% of ankle OA the etiology is of post-traumatic origin (e.g. ankle fracture, maleolus fracture, ligament rupture) (Saltzman et al., 2005, Thomas and Daniels, 2003). The other percentages are distributed in secondary (ankle arthritis; as rheumatoid arthritis, other inflammatory arthritis, etc.) and primary arthritis (ankle osteoarthrosis). Due to the increasing rate of ankle arthritis (Baumhauer et al., 1995, Valtola et al., 2002) it is important to understand the effects of ankle arthritis on daily life activities and gait. However, in vivo gait analysis and functional evaluations related to ankle arthritis are rare and have been performed with unspecific ankle arthritis inclusion criteria (Stauffer et al., 1977, Khazzam et al., 2006, Shih et al., 1993). One of the first in vivo gait studies related to ankle arthritis (Stauffer et al., 1977) quantified gait for the normal, the arthritic and for ankle joints treated with total ankle replacement for nine patients with inhomogeneous ankle arthritis etiology. In a recent report (Khazzam et al., 2006) preoperative gait characteristics were quantified for ankle arthritis patients in a heterogenic etiology group.

The goal of orthopaedic end-stage ankle OA treatment is to relieve symptoms, such as pain and stiffness, and improve function. Historically, ankle arthrodesis has been the typically chosen orthopaedic treatment for ankle OA (Mazur et al., 1979). Complications in ankle arthrodesis, such as degeneration of neighboring hindfoot joints, non- and mal-unions (Mann and Rongstad, 1998, Muir et al., 2002, Fuchs et al., 2003) led to the introduction of total ankle replacement (TAR) designs and novel TAR implantation techniques (Valderrabano et al., 2004, Anderson et al., 2003, Kofoed and Stürup, 1994, Hintermann et al., 2004). In the last decade, TAR was an often chosen treatment modality for end-stage ankle OA. Most of the TAR biomechanics studies have been performed in an in vitro or simulation environment (Tochigi et al., 2005, Michelson et al., 2000, Reggiani et al., 2006, Valderrabano et al., 2003), or in a clinical outcome context (Valderrabano et al., 2004, Fong SooHoo and Kominski, 2004, Kofoed and Stürup, 1994, Hintermann et al., 2004). In vivo biomechanical TAR studies are rare (Demottaz et al., 1979, Dyrby et al., 2004) and little is known about the gait characteristics of TAR patients before, after TAR, and during the rehabilitation process following surgery. It is not known how much TAR can improve ankle OA patients’ function. However, objective gait information in the first year after TAR could be used for the design of effective TAR rehabilitation programs and, therefore, for the long-term success of the implanted TAR system. An objective analysis of the changes in kinematics and kinetics of TAR patients can not be obtained from physical examination but can be provided by gait analysis.

Therefore, the purpose of this prospective study was to determine the clinical and gait characteristics of ankle OA patients before and after total ankle replacement during one year of follow-up and in 3 months intervals.

The following hypotheses were tested:

• Ankle OA will result in a substantial change of the clinical scores (American Orthopaedic Foot and Ankle Society (AOFAS) ankle score, Short Form-(SF)-36 health survey score) and kinematic and kinetic gait parameters (spatiotemporal variables, dynamic range of motion, ground reaction force, ankle joint moment, ankle joint power).

• Based on the authors’ clinical experience, during the first three months following TAR surgery, the clinical and biomechanical variables will be lower than the preoperative baseline and differ from the values of the normal population.

• Based on the authors’ clinical experience, after three months following TAR surgery, the clinical and biomechanical variables will approach the values of the normal subjects group.