Factors Related to Postoperative Pain Trajectories following Total Knee Arthroplasty: A Longitudinal Study of Patients Admitted to a Russian Orthopaedic Clinic
Table 1
Sample Characteristics and their Relationship to Pain on Postoperative Days 0 to 3.
Mean (SD)
% ()
Relationships to pain severity in activity ()
Relationships to hours in moderate to severe pain ()
Demographic characteristics
Age in years, (range 47–81)
63.5 (7.8)
None (using cutpoint of 65)
None (using cutpoint of 65)
Sex
Main effect for sex, (more pain for females)
Interaction of sex and time, (more hours of pain for females)
Male
7% (7)
Female
93% (93)
Living situation
None
None
Lives alone
18% (18)
Lives with spouse
58% (58)
Lives with other(s)
24% (24)
Education
None
None
Less than high school
45% (45)
Completed high school
55% (55)
Employment status
None
None
Paid work or self-employed
24% (24)
No paid work or retired
76% (76)
Preoperative clinical characteristics
EQ VAS health-related quality of life (0–100 scale)
55.6 (15.6)
Main effect for EQ VAS, (healthier patients reported slightly more pain)
None
<80
88% (88)
Fatigue Severity Scale (1–7 scale)
3.17 (1.66)
None (using cutpoint of either 4 or 5)
None (using cutpoint of either 4 or 5)
≥5
14% (14)
≥4
28% (28)
Pittsburgh Sleep Quality Index
8.35 (3.50)
None (using cutpoint of 5)
None (using cutpoint of 5)
>5
73% (73)
HADS Depression Subscale
6.12 (4.03)
None
None
0–8 (none)
70% (70)
9-10 (mild)
17% (17)
>10 (moderate/severe)
13% (13)
HADS Anxiety Subscale
7.34 (4.18)
Interaction of anxiety and time, (anxious patients reported more pain on day 0, but not after
Main effect of anxiety, ; interaction of anxiety and time, (anxious patients had more hours of pain, particularly on days 0 and 1)
0–8 (none)
61% (61)
9-10 (mild)
20% (20)
>10 (moderate/severe)
19% (19)
BPI Average preoperative pain rating (0–10 scale)
4.76 (2.54)
None (using cutpoint of either 4 or 7)
Main effect for pre-operative pain ≥4, (patients with more pre-op pain reported more hours of post-op pain)
≥4 (moderate or severe pain)
67% (67)
≥7 (severe pain)
24% (24)
IADL (0–8 scale) ()
6.43 (1.10)
None (median split at 6)
None (median split at 6)
KSS Knee Score (0–100 scale)
33.5 (20.3)
None (median split at 30)
None (median split at 30)
KSS Function score (0–100 scale)
45.2 (17.1)
None (median split at 44)
None (median split at 44)
Surgery characteristics
Anesthesia
Not analyzed
Not analyzed
Spinal/sedation
99% (99)
TIVA
1% (1)
Surgery duration in minutes (range 50–210)
95.6 (23.6)
Main effect for surgery duration, (more pain for surgeries >90 minutes)
Main effect for surgery duration, (more hours of pain for surgeries >90 mins)
Implant type
None
Main effect for implant, (common implants [first 2] had slightly less hours of pain than uncommon implants [last 3])
Sigma (DePuy Johnson & Johnson)
43% (43)
AGC (Zimmer Biomet)
34% (34)
LCS (DePuy Johnson & Johnson)
14% (14)
Scorpio NRG (Stryker)
5% (5)
NexGen (Zimmer Biomet)
4% (4)
Tourniquet use
21% (21)
None
None
Bleeding (ml)
341.7 (183.2)
None
Main effect for bleeding, (slightly more hours of pain for bleeding > 300 ml)
Hemoglobin (g/L)
Main effect for preop Hgb, (slightly more pain among patients with preop Hgb ≥ 120). When only women are included, . No effects for postop Hgb, but the numbers with normal postop Hgb were small.
Main effect for preop Hgb, (slightly more hours of pain among patients with higher preop Hgb ≥ 120). When only women are included, . No effects for postop Hgb, but the numbers with normal postop Hgb were small.
Females ()
Pre-operative (% () < 120)
128.6 (12.0)
26% (24)
Day 0 at 20:00 (% () < 120)
106.9 (11.7)
89% (83)
Day 4 (% () < 120)
99.0 (13.4)
92% (86)
Males ()
Pre-operative (% () < 120)
139.1 (12.3)
0% (0)
Day 0 at 20:00 (% () < 120)
110.1 (11.9)
71% (5)
Day 4 (% () < 120)
106.4 (14.4)
86% (6)
C-reactive protein, preoperative (mg/L)
4.07 (5.40)
None (split at 5)
None (split at 5)
≥5
24% (24)
Creatinine, preoperative (mcmol/L)
None (split at 44)
None (split at 44)
Female () (% () < 44)
63.9 (16.5)
5% (5)
Males () (% () < 44)
79.8 (15.7)
0% (0)
Length of hospital stay in days
None (median split at 16)
None (median split at 16)
Pre-operative
7.2 (4.1)
Post-operative
9.2 (2.4)
Total
16.4 (4.3)
Note. Relationships to pain were determined by including each variable as a between-subjects factor in a repeated measures analysis of pain in activity and hours in moderate/severe pain. Variables with gender differences were evaluated both with and without men. Five patients were missing IADL total score because they answered “does not apply” to more than 2 of the IADL items.
