Ad. Milne et al., Design and validation of an unconstrained loading system to measure the envelope of motion in the rabbit knee joint, J BIOMECH E, 123(4), 2001, pp. 347-354
Citations number
39
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Multidisciplinary
Journal title
JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME
An unconstrained loading system was developed to measure the passive envelo
pe of joint motion in an animal model commonly used to study ligament heali
ng and joint arthritis. The design of the five-degree-of-freedom system all
owed for unconstrained knee joint loading throughout flexion with repeated
removal and reapplication of the device to a specimen. Seven New Zealand Wh
ite rabbit knees it-ere subjected to varus, valgus, internal and external l
oads, and the resulting envelopes of motion were recorded using an electrom
agnetic tracking device. Intra-specimen reproducibility was excellent when
measured in one specimen, with maximal rotational differences of 0.6 and 0.
3 deg between the fourth and fifth testing cycles for the varus (VR) and va
lgus (VL) envelopes, respectively. Similarly, the maximal internal (INT) an
d external (EXT) envelope differences were 0.5 and 0.4 deg, respectively, b
etween the fourth and fifth cycles. Good inter-animal envelope reproducibil
ity was also observed with consistent motion pathways for each loading cond
ition. A maximal VR-VL laxity of 17.9+/-2.3 deg was recorded at 95 deg flex
ion for the seven knees tested. The maximal INT-EXT laxity of 75.2+/-4.8 de
g occurred at 50 deg flexion. Studies on measurement reproducibility of re-
applying individual testing components demonstrated a maximal error of 1.2/-0.7 deg. Serial removal and re-application (test-retest) of the complete
measuring system to one cadaveric knee demonstrated maximal envelope differ
ences of less than 0.7 deg for VR-VL rotation and 2.1 deg for INT-EXT rotat
ion. Our results demonstrate that the measuring system is reproducible and
capable of accurate evaluation of knee joint motion. Baseline in vitro data
were generated on normal joint kinematics for future in-vivo studies with
this system, evaluating ligament healing and disease progression in arthrit
is models.