Validity of gait parameters for hip flexor contracture in patients with cerebral palsy.
BACKGROUND
Psoas contracture is known to cause abnormal hip motion in patients with cerebral palsy. The authors investigated the clinical relevance of hip kinematic and kinetic parameters, and 3D modeled psoas length in terms of discriminant validity, convergent validity, and responsiveness.


METHODS
Twenty-four patients with cerebral palsy (mean age 6.9 years) and 28 normal children (mean age 7.6 years) were included. Kinematic and kinetic data were obtained by three dimensional gait analysis, and psoas lengths were determined using a musculoskeletal modeling technique. Validity of the hip parameters were evaluated.


RESULTS
In discriminant validity, maximum psoas length (effect size r = 0.740), maximum pelvic tilt (0.710), maximum hip flexion in late swing (0.728), maximum hip extension in stance (0.743), and hip flexor index (0.792) showed favorable discriminant ability between the normal controls and the patients. In convergent validity, maximum psoas length was not significantly correlated with maximum hip extension in stance in control group whereas it was correlated with maximum hip extension in stance (r = -0.933, p < 0.001) in the patients group. In responsiveness, maximum pelvic tilt (p = 0.008), maximum hip extension in stance (p = 0.001), maximum psoas length (p < 0.001), and hip flexor index (p < 0.001) showed significant improvement post-operatively.


CONCLUSIONS
Maximum pelvic tilt, maximum psoas length, hip flexor index, and maximum hip extension in stance were found to be clinically relevant parameters in evaluating hip flexor contracture.
Department of Orthopedic Surgery, Synergy Hospital, 115-17 Nonhyun-Dong, Kangnam-Gu, Seoul, 135-010, Republic of Korea.
Sun Jong
SJ
Choi
Chin Youb
CY
Chung
Kyoung Min
KM
Lee
Dae Gyu
DG
Kwon
Sang Hyeong
SH
Lee
Moon Soek
MS
Park
D001696:Biomechanical Phenomena; D002547:Cerebral Palsy / Q000503:physiopathology*; D002648:Child; D003286:Contracture / Q000503:physiopathology*; D003627:Data Interpretation, Statistical; D005260:Female; D005684:Gait / Q000502:physiology*; D020233:Gait Disorders, Neurologic / Q000175:diagnosis / Q000503:physiopathology; D006615:Hip / Q000503:physiopathology*; D006801:Humans; D007700:Kinetics; D008297:Male; D016658:Psoas Muscles / Q000033:anatomy & histology / Q000503:physiopathology*; D015203:Reproducibility of Results
J Pediatr Orthop. 1997 Sep-Oct;17(5):563-70
9591993
Gait Posture. 2000 Oct;12(2):122-7
10998608
J Pediatr Orthop. 2006 Mar-Apr;26(2):260-4
16557146
Arch Orthop Trauma Surg. 1989;108(4):225-30
2774874
Psychol Bull. 1959 Mar;56(2):81-105
13634291
J Biomech. 1981;14(11):803-12
7334040
J Pediatr Orthop. 2009 Apr-May;29(3):251-5
19305275
J Pediatr Orthop. 1986 May-Jun;6(3):285-90
3711319
J Pers Soc Psychol. 2003 Mar;84(3):608-18
12635920
Gait Posture. 2002 Dec;16(3):288-96
12443954
IEEE Trans Biomed Eng. 1990 Aug;37(8):757-67
2210784
Clin Orthop Relat Res. 1974 Jul-Aug;(102):4-9
4607726
J Bone Joint Surg Am. 1986 Apr;68(4):629-31
3514626
J Orthop Res. 1996 Jan;14(1):144-51
8618157
J Orthop Res. 1997 Jul;15(4):615-21
9379273
J Bone Joint Surg Br. 1993 Jul;75(4):534-7
8331105
J Trauma Stress. 1999 Jan;12(1):193-9
10027153
J Bone Joint Surg Am. 1971 Dec;53(8):1468-88
5121790
J Bone Joint Surg Br. 2004 Mar;86(2):251-8
15046442
Gait Posture. 2007 Oct;26(4):532-8
17208000
Dev Med Child Neurol. 1997 Apr;39(4):214-23
9183258
J Pediatr Orthop. 1987 Nov-Dec;7(6):690-8
3429656
Behav Res Ther. 1995 Jun;33(5):589-95
7598683
Biomed Mater Eng. 1998;8(3-4):227-40
10065889