Are outcomes after total knee arthroplasty worsening over time? A time-trends study of activity limitation and pain outcomes

Table 2 Time-trends in moderate-severe preoperative pain and functional limitation

	1993-1995 (n ~ 1,510)*	1996-1998 (n ~ 1,646)*	1999-2001 (n ~ 1539)*	2002-2005 (n ~ 2,480)*	Absolute Difference (period 1 -period 4)	p-value for time-trend
Preoperative walking limitations						<0.001
None/Mild	25.7%	25.9%	32.2%	31.4%
Moderate/Severe	74.3%	74.1%	67.8%	68.6%	-5.7%
Preoperative stairs limitations						0.007
None/Mild	14.4%	15.5%	16.7%	12.7%
Moderate/Severe	85.6%	84.5%	83.3%	87.3%	+1.7%
Preoperative chair limitations						<0.001
None/Mild	58.4%	65.3%	71.2%	76.8%
Moderate/Severe	41.6%	34.7%	28.8%	23.2%	-18.4%
Preoperative walking aids						0.025
No/mild dependence	70.9%	71.9%	72.0%	75.3%
Moderate dependence	18.3%	16.4%	16.7%	15.4%	-2.9%
Complete dependence or unable to walk	10.8%	11.7%	11.3%	9.3%	-1.5%
Preoperative overall ADL limitations						<0.001
None/Mild	24.8%	27.9%	34.6%	32.1%
Moderate/Severe	75.2%	72.1%	65.4%	67.9%	-7.3%
Preoperative pain						<0.001
None/Mild/Stairs/Stairs and walking	35.7%	39.4%	41.8%	33.0%
Moderate/Severe	64.3%	60.6%	58.2%	67.0%	+2.7%

ADL, activities of daily living.
*Missingness ranged from 1% to 3% for various variables, since not all the patients answered each question on the survey.