Impact of instrumental analysis of stiff knee gait on treatment appropriateness and associated costs in stroke patients

BACKGROUND: Stiff Knee Gait (SKG) in stroke patients is typically treated by the
inhibition of the rectus femoris (RF) with botulinum toxin (BoNT) after clinical
evaluation, obtaining an average pooled recovery in knee flexion (KF) of 7
degrees.
PURPOSE: Our hypothesis is that this limited recovery after BoNT could depend on
the inadequacy in the selection of patients to be treated. The aim of this study
was to assess the percentage of inappropriate treatments (PIT) that can be
avoided when instrumental gait analysis (GA) is used, and to estimate the
associated cost savings.
METHODS: We retrospectively analyzed GA data from chronic stroke patients with
SKG and clinically assessed knee extensors spasticity referred to our laboratory
over a five-year period. Gait kinematics and dynamic electromyography data were
used. Patients were considered unsuitable for RF inhibition when: their SKG was
determined by inadequate ankle push-off (APO) rather than by a brake from knee
extensors, based on a previously published algorithm using gait kinematics
(PITKIN); when RF was not active during KF (PITEMG); and when a proximal braking
mechanism was found, if this was not due to RF activity (PITGA).
RESULTS: 160 patients, age 20-87 years, gait speed 9-77%height/s, KF peak -4-44
degrees, were included. Of these, in 119 cases poor APO was the main cause of
SKG, thus leading to PITKIN = 74%. In 48 out of 107 non-obese subjects, RF
spasticity was not involved in SKG, resulting in PITEMG = 45%. Finally, patients
with a braking activity as the main cause and concurrent RF activity were
20/107 = 19%, resulting in PITGA = 81% SIGNIFICANCE: When treating SKG, proper
use of GA can reduce the percentage of inappropriate treatments by BoNT at the RF
up to 81%. Savings are in the order of €100k/year when considering centers
treating 100 or more patients/year.