Two-year recovery courses of physical and mental impairments, activity limitations, and participation restrictions after total knee arthroplasty among working-age patients

Figures & data

Figure 1. Flowchart.

Table 1. Baseline characteristics.

Variable	Participants (n = 146)
Age, mean (SD) (range)	55.2 (5.0) (38–62)
Female, n (%)	82 (56)
BMI, n (%)
18.5–24.9	24 (17)
25.0–29.9	62 (43)
>30.0	60 (40)
Comorbidity, n (%)
0	9 (7)
1	30 (23)
2 or more	89 (70)
Educational level, n (%)
Low	49 (35)
Medium	66 (47)
High	26 (18)
Home situation, n (%)
Living alone	50 (34)
Living with partner	85 (58)
Living with partner and children	11 (8)

BMI: body mass index.

Table 2. Results of linear mixed models of physical and mental impairments, activity limitations, and participation restrictions over 2 years’ time.

Construct and measures	Preoperatively	Postoperatively
	Preoperatively (T0) (n = 145)^d	6 weeks (T1) (n = 130)^d	3 months (T2) (n = 124)^d	6 months (T3) (n = 120)^d	12 months (T4) (n = 115)^d	24 months (T5) (n = 96)^d
	Estimate (95% CI)	Estimate (95% CI) ΔT1–T0^e	Estimate (95% CI) ΔT2–T1 (ΔT2–T0)^e	Estimate (95% CI) Δ(T3–T2) (ΔT3–T0)^e	Estimate (95% CI) ΔT4–T3 (ΔT4–T0)^e	Estimate (95% CI) ΔT5–T4 (ΔT5–T0)^e	p-Value^a
Physical impairments
General pain	39.3 (35.9–42.7)	44.6 (40.9–48.2)	63.6 (60.0–67.3)	71.9 (68.2–75.6)	76.7 (73.0–80.5)	77.5 (73.5–81.6)	<0.001
(RAND-36)	Ref	13.3%, p = 0.01^b	42.8% (61.9%), p < 0.001^b	13.0% (82.9%), p < 0.001^b	6.7% (95.1%), p < 0.001^b	1.1% (97.2%), p < 0.001^b
Knee-specific pain	42.1 (39.3–44.8)	72.7 (69.9–75.6)	78.8 (75.9–81.7)	84.3 (81.3–87.2)	87.2 (84.3–90.2)	87.4 (84.2–90.5)	<0.001
(WOMAC)	Ref	72.9%, p < 0.001^b	8.4% (87.4%), p < 0.001^b	7.0% (100.5%), p < 0.001^b	3.4% (107.4%), p < 0.001^b	0.2% (107.8%), p < 0.001^b
Vitality	60.4 (57.3–63.4)	61.3 (58.2–64.5)	66.8 (63.6–69.9)	69.5 (66.3–72.6)	70.2 (66.7–73.5)	68.1 (64.6–71.5)	<0.001
(RAND-36)	Ref	1.6%, p = 0.5^b	8.9% (10.7%), p < 0.001^b	4.1% (15.2%), p < 0.001^b	1.0% (16.3%), p < 0.001^b	−3.0% (12.8%), p < 0.001^b
Stiffness	42.2 (38.9–45.4)	58.6 (55.2–62.1)	62.0 (58.5–65.5)	70.3 (66.7–73.8)	75.3 (71.7–78.8)	75.0 (71.2–78.8)	<0.001
(WOMAC)	Ref	39.1%, p < 0.001^b	5.7% (47.1%), p < 0.001^b	13.3% (66.6%), p < 0.001^b	7.1% (78.5%), p < 0.001^b	–0.4% (77.8%), p < 0.001^b
Mental impairments
Mental health	78.4 (76.1–80.6)	80.1 (77.7–82.4)	84.6 (82.2–86.9)	84.5 (82.1–86.9)	83.1 (80.7–85.5)	84.0 (81.5–86.6)	<0.001
(RAND-36)	Ref	2.2%, p = 0.13^b	5.6% (7.9%), p < 0.001^b	−0.1% (7.8%), p < 0.001^b	−1.6% (6.1%), p < 0.001^b	1.1% (7.2%), p < 0.001^b
Depressive symptoms	85.3 (83.0–87.6)	81.4 (79.0–83.8)	86.5 (84.1–88.9)	91.1 (88.7–93.6)	89.5 (87.0–92.0)	90.7 (88.0–93.3)	<0.001
(PHQ-9)	Ref	−4.6%, p = 0.002^b	6.3% (1.4%), p = 0.4^b	5.4% (6.8%), p < 0.001^b	−1.8% (4.9%), p = 0.002^b	1.3% (6.3%), p < 0.001^b
Activity limitations
General physical functioning	32.1 (28.7–35.4)	43.7 (40.2–47.2)	55.6 (52.1–59.2)	64.4 (60.8–68.0)	68.7 (65.1–72.3)	68.4 (64.5–72.3)	<0.001
(RAND-36)	Ref	36.2%, p < 0.001^b	27.4% (73.6%), p < 0.001^b	15.8% (101.0%), p < 0.001^b	6.7% (114.3%), p < 0.001^b	–0.4% (113.5%), p < 0.001^b
Knee-specific physical functioning	48.5 (45.7–51.2)	68.9 (66.0–71.8)	74.3 (71.3–77.2)	80.6 (77.6–83.6)	84.3 (81.3–87.3)	84.8 (81.6–88.0)	<0.001
(WOMAC)	Ref	42.2%, p < 0.001^b	7.8% (53.2%), p < 0.001^b	8.5% (66.3%), p < 0.001^b	4.6% (74.0%), p < 0.001^b	0.6% (75.0%), p < 0.001^b
Participation restrictions
Social functioning	70.3 (66.7–73.9)	65.6 (61.8–69.3)	80.9 (77.1–84.7)	87.1 (83.2–90.9)	86.4 (82.5–90.4)	87.4 (83.2–91.6)	<0.001
(RAND-36)	Ref	−6.7%, p = 0.02^b	23.3% (15.1%), p < 0.001^b	7.6% (23.9%), p < 0.001^b	−0.7% (23.0%), p < 0.001^b	1.1% (24.3%), p < 0.001^b
Work role functioning	79.2 (75.8–82.3)	n.a.^c	83.0 (79.1–86.8)	5.3 (81.9–88.8)	89.6 (86.2–93.0)	87.5 (83.7–91.2)	<0.001
(WRFQ)	Ref		n.a. (5.0%), p = 0.05^b	2.9% (7.9%), p < 0.001^b	5.1% (13.4%), p < 0.001^b	−2.4% (10.6%), p < 0.001^b

^ap-Value of improvement over time; ^bp-value of specific follow-up moment compared to preoperative level; ^cnot applicable while WRFQ was not assessed at 6 weeks; ^dnumber of patients per measure may vary due to missing data; ^efirst percentage represents improvement between two consecutive follow-up moments, percentage between brackets represents improvement of follow-up moment compared to the preoperative level. All measures are scaled from 0–100 whereby higher scores indicate less impairments, limitations or restrictions.

Table 3. Final models showing significant associations of sociodemographic and health-related factors with physical and mental impairments, activity limitations and participation restrictions.

	Physical impairments				Mental impairments		Activity limitations		Participation restrictions
	General pain	Knee-specific pain	Stiffness	Vitality	Mental health	Depressive symptoms	General physical functioning	Knee-specific physical functioning	Social functioning	Work functioning
	B (95%CI), p-value	B (95%CI), p-value	B (95%CI), p-value	B (95%CI), p-value	B (95%CI), p-value	B (95%CI), p-value	B (95%CI), p-value	B (95%CI), p-value	B (95%CI), p-value	B (95%CI), p-value
Age	1.1 (0.5, 1.6), <0.001	0.6 (0.1, 1.2), 0.01	0.7 (0.2, 1.2), 0.008	0.9 (0.5, 1.4), <0.001	0.5 (0.1, 0.9), 0.007	0.6 (0.3, 1.0), <0.001	1.0 (0.5, 1.5), <0.001	0.6 (0.3, 1.0), 0.01	1.1 (0.6, 1.6), <0.001	0.7 (0.2, 1.2), 0.01
Male gender			6.8 (1.7, 11.8), 0.009		4.2 (0.4, 8.0), 0.03		4.9 (0.0, 9.8), 0.05
Education
Low									12.4 (4.0, 20.7), 0.004
Medium									7.6 (−0.1, 15.2), 0.05
High									Ref
Comorbidity
None	6.8 (-2.9, 6.5), 0.17			8.2 (−0.8, 17.1), 0.07			12.5 (3.3, 21.8), 0.009		6.6 (−3.7, 16.9), 0.21
1	6.6 (0.5, 12.8), 0.04			7.7 (2.2, 13.2), 0.007			8.0 (2.3, 13.8), 0.007		7.5 (0.9, 14.0), 0.03
≥2	Ref			Ref			Ref		Ref

BMI: body mass index; CI: confidence interval. All dependent outcomes are scaled 0–100 whereby higher scores indicate less impairments, limitations or restrictions. Bold values indicate significant associations (p ≤ 0.05).