Correlation between single limb support phase and self-evaluation questionnaires in knee osteoarthritis populations

Figures & data

Table I. Baseline patient characteristics (n  ==  125).

Total
	Frequency	Mean	SD	Percentage (%%)
Male gender	46			37
Age (years)		65.9	11.2
Height (cm)		160	8.7
Weight (kg)		82.1	15.8
Body mass index (BMI) (kg/m^2)		31.9	5.9
Left leg length (cm)		83.0	5.9
Right leg length (cm)		82.9	5.8
K&L** Scale Grade 1	26			20.8
K&L Scale Grade 2	32			25.6
K&L Scale Grade 3	35			28
K&L Scale Grade 4	32			25.6

**Kellgren & Lawrence.

Table II. Spatio-temporal parameters measured by gait analysis.

Parameter	Minimum	Maximum	Mean (SD)
Velocity (cm/s)	25.8	147.9	94.3 (23.0)
Normalised velocity (cm/s/leg length)	0.33	1.73	1.13 (0.3)
Cadence (steps/min)	65.8	131.3	105.3 (12.6)
Step length left (cm)	21.1	77.3	52.9 (9.3)
Step length right (cm)	19.1	76.2	53.4 (9.3)
Normalised step length left (cm/leg length)	0.27	0.86	0.63 (0.1)
Normalised step length right (cm/leg length)	0.25	0.88	0.64 (0.1)
Single limb support left (%% gait cycle)	24.0	42.4	36.5 (3.3)
Single limb support right (%% gait cycle)	25.0	42.9	36.9 (3.1)

Table III. WOMAC osteoarthritis index and SF-36 health survey scores.

Parameter	Minimum	Maximum	Mean (SD)
WOMAC
Pain	0	9.6	4.4 (2.6)
Function	0	9.6	4.4 (2.7)
SF-36
Physical functioning	0	100	46.4 (25.4)
Role limitation due to physical health	0	100	47 (40.6)
Role limitation due to emotional problems	0	100	63.9 (41)
Energy/fatigue	0	100	55.4 (22.0)
Emotional well being	12	100	70.3 (18.3)
Social functioning	0	100	73.5 (25.7)
Pain	0	100	46.3 (26.3)
General health	12.5	91.7	58.6 (16.9)

Table IV. Correlation between the WOMAC-pain, WOMAC-function, SF-36 sub-categories, normalised velocity, normalised step length parameters and both K&L scale and SLS.

Parameter	K&L^† Grading Scale (0–4), r^‡	95%% CI	Single limb support, r^‡	95%% CI	p**
WOMAC^§
Pain	0.26	0.07–0.4	−0.50	−0.62 to −0.35	0.01
Function	0.34	0.17–0.48	−0.53	−0.63 to −0.37	0.03
SF-36^¶
Physical functioning	−0.39	−0.53 to −0.23	0.49	0.34–0.61	0.25
Energy/fatigue	−0.15****	−0.32 to –0.03	0.33	0.16–0.48	0.06
Pain	−0.23	−0.39 to −0.06	0.50	0.36–0.62	≤0.01
General health	−0.21	−0.37 to −0.04	0.36	0.20–0.50	0.12
Normalised velocity	−0.33	−0.48 to −0.16	0.81	0.74–0.86	<0.01
Normalised step length	−0.37	−0.51 to −0.21	0.77	0.69–0.83	<0.01

**p values refer to significant differences between Pearson correlation coefficients of the questionnaires to SLS and to K&L according to the method of Meng et al.

****Not statistically significant (p  ==  0.154).

^†Kellgren and Lawrence.

^‡r  ==  Pearson correlation coefficient.

^§Western Ontario and McMaster University Osteoarthritis Index.

^¶Medical outcomes study 36-item short-form health survey.

Table V. Distribution of mean SLS values over WOMAC-pain quartiles.

	WOMAC**-pain (cm) quartiles
	Q1	Q2	Q3	Q4
	≤2.1	2.1–4.5	4.5–6.2	≥6.2
SLS^† (%%)^‡	37.7	36.1	35.5	33.4
95%% C.I.	37.0–38.5	35.1–37.1	34.5–36.5	32.0–34.7

**Western Ontario and McMaster University Osteoarthritis Index.

^†Single limb support.

^‡One-way ANOVA test. Significance level was set at p  <  0.05. Significant differences in SLS were found over the quartiles.

Table VI. Distribution of mean SLS values over WOMAC-function quartiles.

	WOMAC**-function (cm) quartiles
	Q1	Q2	Q3	Q4
	≤2.3	2.3–4.4	4.4–6.5	≥6.5
SLS^† (%%)^‡	37.9	36.4	34.6	33.8
95%% C.I.	37.2–38.7	35.5–37.3	33.7–35.4	32.3–35.2

^†Western Ontario and McMaster University Osteoarthritis Index.

^‡Single limb support.

^‡One-way ANOVA test. Significance level was set at p  <  0.05. Significant differences in SLS were found over the quartiles.

Table VII. Distribution of mean SLS values over SF-36 overall score quartiles.

	SF-36** Overall Score quartiles
	Q1	Q2	Q3	Q4
	≤40	40–55	55–71	≥71
SLS^† (%%)^‡	32.9	35.4	36.8	37.7
95%% C.I.	31.6–34.2	34.4–36.3	35.8–37.8	37.0–38.4

**Medical outcomes study 36-item short-form health survey.

^†Single limb support.

^‡One-way ANOVA test. Significance level was set at p  <  0.05. Significant differences in SLS were found over the quartiles.

Figure 1.  Single limb support distribution according to (a) WOMAC-pain, (b) WOMAC function and (c) SF-36 overall score quartiles. The box plots represent the median value of SLS with the range of the 1st quartile and the 3rd quartile.