Although total knee replacement (TKR) is an effective intervention for end-stage arthritis of the knee, a significant number of patients remain dissatisfied following this procedure. Our aim was to identify and assess the factors affecting patient satisfaction following a TKR.
Materials and methods
In accordance with the PRISMA guidelines, two reviewers searched the online databases for literature describing factors affecting patient satisfaction following a TKR. The research question and eligibility criteria were established a priori. Any clinical outcome study that described factors relating to overall satisfaction after primary TKR was included. Quality assessment for the included studies was performed by two accredited orthopaedic surgeons experienced in clinical research.
Results
The systematic review identified 181 relevant articles in total. A history of mental health problems was the most frequently reported factor affecting patient satisfaction (13 reportings). When the results of the quality assessment were taken into consideration, a negative history of mental health problems, use of a mobile-bearing insert, patellar resurfacing, severe pre-operative radiological degenerative change, negative history of low back pain, no/less post-operative pain, good post-operative physical function and pre-operative expectations being met were considered to be important factors leading to better patient satisfaction following a TKR.
Conclusion
Surgeons performing a TKR should take these factors into consideration prior to deciding whether a patient is suitable for a TKR. Secondarily, a detailed explanation of these factors should form part of the process of informed consent to achieve better patient satisfaction following TKR. There is a great need for a unified approach to assessing satisfaction following a TKR and also the time at which satisfaction is assessed.
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Introduction
Total knee replacement (TKR) is one of the most effective surgical interventions for relief of pain and functional recovery in patients with advanced osteoarthritis (OA) of the knee. Management of OA costs the UK economy equivalent to 1% of its gross national product per year [1]. In the USA, the annual number of TKRs has been projected to rise by over 670% to 3.48 million cases by 2030 [2]. Outcomes of TKR are traditionally assessed by survival analysis with revision as the end point, and technical outcomes of this intervention are excellent. According to the UK National Joint Registry (NJR) annual report, the survival rate has been reported to be over 99.5% after one year and 95.6% at ten years [3].
A revision TKR is most commonly performed for loosening, fracture or infection. However, survival analysis tends to underestimate poor function, pain or dissatisfaction because these problems do not necessarily lead to a revision and are not recorded in the registry. Another issue is that reporting of the outcome of a TKR has predominantly been based on surgeon-derived outcome measures, which include range of movement (ROM), joint stability and post-operative alignment [4‐6]. However, a report identified a poor correlation between surgeon-derived and patient-reported outcomes, with surgeons overestimating outcomes in comparison with the patients’ [7]. This correlates well with the fact that a significant number of patients experience continual pain and functional disability and therefore remain dissatisfied following the procedure [8‐10].
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In the largest ever reported series on satisfaction following a TKR, which included a survey of 27,372 patients, 17% of the unrevised patients were either dissatisfied or uncertain regarding their outcome [11]. Baker et al. [12] also reviewed the data from the NJR in the UK and reported that 71% of the patients experienced improvement of knee symptoms, but only 22% of them rated the results as excellent. Therefore, although the surgeon-reported outcomes may be good and the patient has no indication for a revision, they may still be dissatisfied following their index TKR. This may be due to a multitude of reasons, but to the best of our knowledge, there has been no systematic review which has specifically focused on the factors that affect patient satisfaction following a TKR. The aim of this systematic review, therefore, was to identify and assess the factors affecting patient satisfaction following a TKR.
Methods
The protocol of this systematic review was developed and has been registered in the International Prospective Register of Systematic Reviews (PROSPERO 2017 CRD42017084659). The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used for designing this study [13].
Search strategy
Two accredited orthopaedic surgeons experienced in clinical research searched the online database Medline, Embase, BNI, AMED, Cochrane and Google Scholar for literature relating to satisfaction following a TKR. The PICO (participants, interventions, comparators, outcomes) tool was adopted and modified to formulate the research question and establish the inclusion and exclusion criteria. Selected articles were then exported to Mendeley reference manager software to organise screen and select articles.
Study screening and selection
Clinical outcome studies that described the factors relating to the overall or general satisfaction/dissatisfaction following a primary TKR irrespective of any pathology were included. The inclusion and exclusion criteria are described in Table 1. Any discrepancies at the title and abstract revision stage were resolved by automatic inclusion to ensure thoroughness. Any discrepancies at the full-text stage were resolved by consensus between the two reviewers. If a consensus could not be reached, a third, more senior reviewer was consulted to resolve the discrepancy.
Table 1
Inclusion and exclusion criteria applied to articles identified in the literature
Inclusion criteria
1. All levels of evidence
2. Written in the English language
3. Studies on humans
4. Studies reporting factors affecting overall satisfaction and/or dissatisfaction following a primary total knee replacement
5. Operative procedure consisted solely of total knee replacement
6. Total knee replacement irrespective of any pathology
Exclusion criteria
1. Studies whose results included other procedures
2. Studies reporting satisfaction/dissatisfaction for only a small part of the procedure (e.g. ‘satisfaction in either pain control, skin closure, range of motion, nursing quality, anaesthesia, nerve block or physiotherapy’ was excluded)
3. Studies not reporting patient’s satisfaction (e.g. ‘studies on family’s or carer’s satisfaction’ were excluded)
4. Studies describing trial protocols without any results
5. Studies with follow-up period of 3 months or less
6. Revision total knee replacement
7. Unicompartmental knee replacement
8. Patellofemoral knee replacement
9. Cadaveric or radiological studies
10. Reviews, systematic reviews
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Data extraction and analysis
The two reviewers independently extracted relevant study data from the final pool of included articles and recorded this data on a spreadsheet designed a priori in Microsoft Excel 2013 (Microsoft Corporation, Redmond, WA, USA). The quality of studies including bias was then analysed and assessed using the Joanna Briggs Institute Critical Appraisal Checklist (JBICAC) for cohort studies, case–control studies, cross-sectional studies and case series [14]. For RCTs, a modified version of critical appraisal checklist by van Tulder et al. was used [15].
Statistical methods
Statistical analysis in this study focused on descriptive statistics. After assessing the quality of each study, the score was converted into a percentage from the full score (%), which was then considered to be the ‘strength’ of that particular study. Microsoft Excel 2013 was used for our analysis in reporting the factors affecting patient satisfaction following a TKR, based on the strength of studies as per the type of evidence. The potential factors were then categorised into seven groups designed from the findings of the studies included. The strength of each factor was presented, regardless of whether it was a FACTOR (‘it is a factor for patient satisfaction’) or a Not-FACTOR (‘it is a factor which does NOT relate to patient satisfaction’—in other words, ‘researcher X found Factor Z was irrelevant to patient satisfaction’).
Details are described in Electronic Supplementary Material 1 and Table 2.
Table 2
Search strategy for Medline
No.
Searches
Medline results
1
satisf$.mp. [mp=title, abstract, original title, name of substance word, subject heading word, keyword heading word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms]
366,508
2
tkr.mp. [mp=title, abstract, original title, name of substance word, subject heading word, keyword heading word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms]
1908
3
tka.mp. [mp=title, abstract, original title, name of substance word, subject heading word, keyword heading word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms]
8888
4
“total knee arthroplasty”.mp. [mp=title, abstract, original title, name of substance word, subject heading word, keyword heading word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms]
15,890
5
“total knee replacement”.mp. [mp=title, abstract, original title, name of substance word, subject heading word, keyword heading word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms]
5129
6
2 or 3 or 4 or 5
21,446
7
dissatisf$.mp. [mp=title, abstract, original title, name of substance word, subject heading word, keyword heading word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms]
17,906
8
1 or 7
374,612
9
6 and 8
2187
Results
A total of 5635 articles were found following the initial search of the electronic databases and citation tracking, followed by removing 2424 duplicate articles. After review by title and abstract, 2977 articles were excluded and 234 potential articles remained for a full-text review. After application of the inclusion and exclusion criteria, a further 53 articles were discarded, leaving 181 relevant articles for the final inclusion, analysis and assessment. The study finally included 40 RCTs (22.1%), 93 cohort studies (51.4%), nine case–control studies (5.0%), 37 cross-sectional studies (20.4%) and 2 case series (1.1%) (Electronic Supplementary Material 2). Flowchart for the review is shown in Fig. 1 and the details of all the 181 studies are shown in Table 3. A total of 22 authors were found to have written several papers. To ensure that duplicate numbers were not included in our analysis, we contacted all these authors and reminder emails were sent as well to ensure a reply. Only five authors replied back with no overlap in their studies, three authors said that there was an overlap and 14 did not reply back. Those who did not reply back were treated as if it was an overlap and, thus, not considered. Due to the lack of homogeneity between studies, a meta-analysis was deemed unsuitable for this study.
Fig. 1
PRISMA flowchart for results of the literature database search
Table 3
Details of 181 included studies (alphabetical order of the first author’s name)
First author
Serial no.
Factors affecting or relating to satisfaction
Measuring method for satisfaction
Year
Country
Type of study
Assessment timing
Number of TKRs
Men
Women
Age
BMI
Primary diagnosis
Surgical approach
Patellar resurface
Prosthesis
Use of cement
Anaesthesia
Adam
1
No difference between age 75 years or older and younger than 75 years
British Orthopaedic Association grading system
1994
UK
Cohort
Minimum 2 years
125
18
67
78 G1
64 G2
NA
OA
NA
NA
NA
NA
NA
Albayrak
2
Patient satisfaction was higher in patients with low pain intensity
4 grades (very satisfied, satisfied, dissatisfied, very dissatisfied)
2016
Turkey
Cross-sectional
22.8 months
274
NA
NA
66.8
32.3
OA
MPP
NA
NA
Yes
Spinal or combined (spinal + epidural)
Ali
3
(1) Very satisfied group had less pain, less anxiety or depression
(2) Mean range of motion was 11 degrees greater in very satisfied group than the dissatisfied group
(1) Patients with pre-operative anxiety or depression had more than 6 times higher risk to be dissatisfied compared with patients with no anxiety or depression (P < 0.001)
(2) Patients with deep prosthetic infection had 3 times higher risk to be dissatisfied with the operation outcome (P < 0.03)
(3) Dissatisfied patients had 1-day longer hospital stay compared with the satisfied patients (P < 0.001)
Of the patients who reported they were as active as they expected to be before TKR, 98.2% were satisfied, while of the patients who reported they were insufficiently active, 52.3% were not satisfied (P < 0.0001)
(2) Poor improvement of range of motion (ROM), pain catastrophizing and depression, severe swelling and unwilling to do post-operative rehabilitation programs related to dissatisfaction
5 grades (very satisfied, satisfied, neutral, dissatisfied or very dissatisfied)
2016
Australia
Cross-sectional
Minimum 1 year
301
142
159
73.9
30
NA
NA
NA
NA
NA
NA
Dickstein
48
Severe pain and inability to use the stairs related to dissatisfaction
Satisfied or not
1997
Israel
Cross-sectional
12 months
79
26
53
70
NA
OA
NA
NA
NA
Yes
NA
Duivenvoorden
49
Patients with pre-operative depressive or anxiety symptoms were less satisfied
5 grades
2013
Netherlands
Cohort
12 months
128
56
72
66.2
NA
OA
NA
NA
NA
NA
NA
Filardo
50
Control Preference Scale related to satisfaction
NRS (0–10)
2016
Italy
Cohort
12 months
176
56
120
66
28.0
OA
MPP
NA
NA
NA
NA
Franklin
51
Patients who used narcotics before TKA were more likely to be dissatisfied
Unclear
2010
USA
Cohort
12 months
6346
2065
4224
67.4
31.9
OA
NA
NA
NA
NA
NA
Fricka
52
No difference between cemented TKR and cementless TKR
Satisfied or not
2015
USA
Randomised controlled trial
2 years
99
37
62
59.3
32.0
NA
Subvastus
Yes
NexGen CR-flex (fixed bearing) (CR)
50 Yes
49 No
NA
Furu
53
Patients with greater knee extensor strength were more satisfied
New KSS (40 points)
2016
Japan
Cohort
1 year
30
4
24
73.6
25.5
OA, RA
MPP
Yes
Bi-surface, NexGen LPS-flex (fixed bearing) (PS)
Yes
NA
Giurea
54
Patients with specific personality traits (life satisfaction, performance orientation and emotional stability) were more satisfied
Satisfied or not
2016
Austria
Cohort
Minimum 2 years
70
32
48
66.0
NA
OA
MPP
Yes
E.motion UC (rotating platform) (CR)
Yes
NA
Gong
55
Significantly different satisfaction rate amongst the four personality: choleric type, 74.2%; sanguine type, 92.3%; melancholic type, 81.2%; phlegmatic type, 87.3%
VAS (0–100)
2014
China
Cross-sectional
6 months
387
109
278
59.6
27.8
OA
NA
NA
Gemini MK II
NA
Epidural or nerve block
Goodman
56
No difference between RA patients and OA patients
5 grades
2016
USA
Cohort
2 years
4456
1852
2604
67.1
30.7
OA, RA
NA
NA
NA
NA
NA
Goudie
57
Patients with post-operative flexion contracture of 5 degrees or greater were less satisfied
The patients who reported ‘very good’ overall satisfaction tended to be younger
5 grades
2017
Russia, Norway
Cohort
1 year
79
4
65
63
NA
OA
MPP
NA
NA
Yes
Spinal
Kosse
96
Satisfaction did not improve by using patient-specific instrumentation
VAS (0–10)
2017
Netherlands
Randomised controlled trial
12 months
42
20
22
63.1
27.95
OA
MPP
Yes
Genesis II (PS, fixed)
Yes
Kotela
97
No difference between patient-specific CT-based instrumentation (signature) and conventional
VAS (0–100)
2015
Poland
Randomised controlled trial
12 months
95
29
66
66.3
29.8
OA
MPP
No
Vanguard (CR)
No
NA
Krushell
98
85% of patients with BMI > 40 were satisfied and 95% of patients with BMI < 30 were satisfied
Satisfied or not
2007
USA
Case–control
90 months
78
NA
NA
68.1
35.0
OA
MPP, midvastus
Yes
Osteonics series 3000, Osteonics series 7000, Scorpio
Yes
NA
Khuangsirikul
99
Computer-assisted TKA did not relate to satisfaction
Original questionnaire
2016
Thailand
Cohort
10 years
144
14
130
76.9
NA
OA
NA
NA
NA
NA
NA
Kuriyama
100
Post-operative noise had no relation to satisfaction
New KSS (40 points)
2016
Japan
Cross-sectional
12 months
35
NA
NA
NA
NA
OA, RA. AVN
NA
NA
Bi-surface (fixed bearing) (PS)
NA
NA
Kuroda
101
No item in pre-operative new Knee Society Scores (objective knee indicators, symptoms, satisfaction, expectations, functional activities) had impact on satisfaction
New KSS (40 points)
2016
Japan
Cohort
1 year
79
12
63
74.8
NA
OA, AVN, RA
NA
NA
PFC Sigma, e-motion
NA
NA
Kwon
102
Generalised joint laxity did not relate to satisfaction
VAS (0–10)
2016
South Korea
Case–control
3 years
338
0
338
68
25.9
OA
MPP
Yes
PFC
Yes
NA
Kwon
103
Intra-operative periarticular injection with corticosteroid did not improve satisfaction
VAS (0–10)
2013
South Korea
Randomised controlled trial
6 months
76
0
76
69.3
25.9
OA
MPP
No
PFC sigma PS
Yes
NA
Lehnen
104
Computer-assisted TKR was better than conventional TKR regarding satisfaction
5 grades (extremely satisfied, very satisfied, moderately satisfied, slightly satisfied, not at all satisfied)
2011
Switzerland
Cohort
12 months
165
59
106
70.0
NA
NA
MPP
NA
LCS (mobile bearing)
Yes
NA
Li
105
Continuous irrigation of 4000 ml cold saline with 0.5% epinephrine group was better than normal temperature solution group
VAS (0–10)
2016
China
Cohort
60 h
389
53
336
61.0
28.7
OA
NA
NA
Gemini Link (CR)
Yes
Epidural or nerve block
Lim
106
No difference between patients with and without history of previous knee surgery (anterior cruciate ligament reconstruction or high tibial osteotomy)
6 grades (excellent, very good, good, fair, poor; terrible)
2016
Singapore
Cross-sectional
2 years
303
220
83
65.0
27.2
OA
MPP
NA
NA
NA
NA
Lingard
107
No difference amongst TKRs undertaken in the USA, UK and Australia
4 grades (very satisfied to very dissatisfied)
2006
USA, UK, Australia
Cohort
12 months
598
254
344
69.3
29.3
OA
NA
Yes and no
Kinemax
Yes
NA
Liow
108
No difference between iASSIST computer-assisted stereotaxic navigation group and conventional group
6 grades
2016
Singapore
Case–control
6 months
192
53
139
65.5
27.9
OA
MPP
NA
NA
NA
NA
Liow
109
No difference between robotic-assisted TKR and conventional TKR
6 grades
2016
Singapore
Randomised controlled trial
2 years
60
NA
NA
67.9
NA
OA
MPP
Yes
NexGen LPS-flex (PS)
NA
NA
Lizaur-Utrilla
110
Patients with mobile bearing insert were more satisfied than those with fixed bearing insert
VAS (0–10)
2012
Spain
Randomised controlled trial
2 years
119
25
94
74.2
32.0
OA
MPP
Yes
Trekking mobile bearing (CR), Multigen Plus fixed bearing (CR)
Hybrid (cemented tibia)
Epidural
Lizaur-Utrilla
111
Dissatisfaction rate was higher in patients waiting longer than 6 months
5 grades (very satisfied, satisfied, neutral, dissatisfied, very dissatisfied)
2016
Spain
Cohort
1 year
192
65
127
69.7
30.7
OA
MPP
Yes
Trekking
Hybrid (cemented tibia)
Spinal
Lizaur-Utrilla
112
Satisfaction was higher in the octogenarian group than the septuagenarian
VAS (0–10)
2016
Spain
Cohort
3.2 years
292
212
80
83.1 G1
75.2 G2
30.2
OA
NA
Yes
Yes
Hybrid
Epidural
Losina
113
Patients having a lack of hospital choice were less satisfied
4 grades (very satisfied, somewhat satisfied, somewhat dissatisfied, very dissatisfied)
2005
USA
Cross-sectional
2 years
932
308
624
74.0
NA
OA, other
NA
NA
NA
NA
NA
Lygre
114
(1) Patella resurfacing did not relate to satisfaction
(B) Patients with NexGen were more satisfied than those with AGC
VAS (0–100)
2010
Norway
Case–control
7.1 years
972
281
691
76.0
NA
OA
NA
Yes and No
AGC (CR), Genesis I (CR), NexGen (CR), LCS (CR)
NA
NA
Machhindra
115
No difference between Ultra Congruent prosthesis and PS prosthesis
There was no relation between surgeon’s pre-operative assessment of the difficulty or surgeon’s immediate post-operative satisfaction and patient’s satisfaction
VAS (0–100)
2009
Netherlands
Cohort
1 year
53
15
36
67.0
NA
OA, RA
NA
NA
PFC, CKS
NA
NA
Merle-Vincent
125
Absence of complications, BMI less than 27, high radiological joint narrowing score, age greater or equal to 70 years and absence of depression positively related to satisfaction
5 grades (0, 25, 50, 75, 100% of satisfaction)
2011
France
Cohort
2 years
264
78
186
75.0
28.4
OA
NA
NA
NA
NA
NA
Miner
126
(1) WOMAC pain score and WOMAC function score were positively related to satisfaction
(2) Knee flexion angle, age, gender and BMI did not relate to satisfaction
4 grades
2003
UK
Cohort
12 months
684
283
401
69.8
29.5
OA
NA
NA
Kinemax
NA
NA
Mistry
127
Presence of altered sensation did not affect satisfaction
British Orthopaedic Association grading system & VAS (0–10)
2005
New Zealand
Cohort
1 year
29
8
21
72.7
NA
NA
NA
NA
NA
NA
NA
Mont
128
Patient’s pre-operative activity level did not relate to satisfaction
VAS (0–10)
2007
USA
Cohort
7 years
144
44
70
70.0
29.0
OA, RA, AVN
NA
NA
Duracon (CR)
NA
NA
Murphy
129
No difference between patients with femoral component implanted in 4 degrees flexion in the sagittal plane and those with femoral component implanted in a neutral position
NRS (0–10)
2014
Australia
Randomised controlled trial
1 year
40
15
25
70.3
30.5
OA
MPP
No
Profix (CR)
NA
NA
Nakahara
130
Post-operative ability of climbing up or down a flight of stairs, getting into or out of a car, moving laterally (stepping to the side) and walking and standing effected on satisfaction
New KSS (questions 3, 4, 5 only)
2015
Japan
Cross-sectional
5 years
520
62
325
72.0
NA
OA, RA, AVN
NA
NA
Unknown (82% PS, 18% CR)
NA
NA
Nakano
131
Use of CT-free navigation had no effect on satisfaction
New KSS (40 points)
2013
Japan
Cohort
118 months
27
3
24
71.5
NA
OA
MPP
NA
PFC Sigma (PS)
NA
NA
Nam
132
Patients with metallic allergy were less satisfied
New KSS (40 points)
2016
USA
Cohort
Minimum 2 years
589
226
363
62.3
32.9
NA
NA
NA
NA
NA
NA
Nam
133
(1) Female patients, patients from low-income households (< USD 25,000 annually) were less satisfied
(2) Education level, employment status and using custom cutting guides, gender-specific prosthesis, high-flex prosthesis, rotating platform bearing or kinematic alignment technique had no effect on satisfaction
Satisfied or not
2014
USA
Cross-sectional
2.6 years
661
NA
NA
54.3
NA
OA
NA
NA
Vanguard
Yes
NA
Nam
134
Using custom cutting guides (signature) had no effect on satisfaction
Satisfied or not
2016
USA
Cohort
3 years
448
154
294
61.9
NA
OA
Midvastus
Yes
Vanguard (fixed bearing) (CR)
Yes
NA
Narayan
135
Deep knee flexion did not relate to patient satisfaction after TKR (even in a population where squatting and sitting cross-legged are part of the normal lifestyle)
Patelloplasty is better than traditional patellar management
Original questionnaire
2012
China
Cohort
55 months
152
72
80
64.7
NA
OA
MPP
No
PFC Sigma
Yes
NA
Thambiah
164
Post-operative WOMAC function scores, post-operative WOMAC final scores, improvements in the physical health component of the SF-36 score, and expectations being met were the factors which effect satisfaction
Chondromalacia patellae did not influence satisfaction
4 grades (very satisfied, satisfied, unsure or dissatisfied)
2017
China
Case series
36 months
290
123
167
67.7
25.0
OA
MPP
No
LCS mobile bearing
Yes
NA
Age are shown in years (mean). Body mass index are shown in kg/m2 (mean). Full information of the studies are listed in Electronic Supplementary Material 1
×
From all these studies, we found 98 factors, which could potentially affect patient satisfaction and these were then categorised into seven groups as follows:
1.
Patient demographics
2.
Non-knee factors
3.
Knee factors
4.
Factors relating to implants/prostheses
5.
Intra-operative technical factors
6.
Post-operative outcome factors
7.
Surgeon and healthcare factors
All the 98 factors as well as scales/scores which were reported to relate to patient satisfaction are summarised in Table 4. Details of the results in each group are described in Electronic Supplementary Material 3. The number of reportings for each group is presented in Fig. 2, and the methods used to measure satisfaction are shown in Table 5.
Table 4
Potential factors for patient satisfaction following primary total knee replacement (TKR) with their groups
Factors
Sub-factors for satisfaction
Serial number of reporting studies
1. Patient demographics (47)
Age (17)
Young
95, 118, 137, 149 (4)
Old
9, 112, 125, 172 (4)
Not-FACTOR
1, 7, 40, 47, 72, 126, 147, 158, 176 (9)
Gender (10)
Male
9, 14, 133, 149 (4)
Female
147 (1)
Not-FACTOR
7, 40, 72, 126, 176 (5)
Body mass index (BMI), weight (12)
Normal BMI
10, 23, 62, 98, 125 (5)
Not-FACTOR
7, 47, 72, 126, 162, 176, 179 (7)
Ethnicity (2)
Caucasian > African American
71 (1)
Not-FACTOR
14 (1)
Income (2)
Annual income > 25,000 USD
14, 133 (2)
Social background (education, employment, insurance) (4)
High education
62 (1)
Not-FACTOR
14, 80, 133 (3)
2. Non-knee factors (30)
Back pain (3)
No low back pain
34, 42, 153 (3)
Allergy (2)
No allergy
121, 132 (2)
Fibromyalgia (1)
No fibromyalgia
15 (1)
Problems in other joints (2)
No problem in other joints
117, 153 (2)
General condition (1)
ASA 2 or worse
9 (1)
Comorbidity (1)
No medical comorbidity
7 (1)
Use of narcotics (1)
No use of narcotics
51 (1)
Diabetes mellitus (1)
Not-FACTOR
35 (1)
Generalised joint laxity (1)
Not-FACTOR
102 (1)
Mental health anxiety, depression and personality traits (15)
Patellar treatment (in cases without patellar resurfacing) (2)
Patellar denervation
143 (1)
Patelloplasty
163 (1)
Use of a tourniquet (1)
Not-FACTOR
9 (1)
Removal of fat pad (1)
Not-FACTOR
9 (1)
One-stage/two-stage bilateral TKR (1)
Not-FACTOR
116 (1)
6. Post-operative outcome factors (55)
Knee alignment (1)
Good post-operative alignment
118 (1)
Pain (8)
No/less pain
2, 3, 7, 9, 29, 48, 170 (7)
No neuropathic pain
146 (1)
Range of motion (9)
Improvement in ROM
3, 47, 59, 72, 86, 176 (6)
Not-FACTOR
45, 126, 135 (3)
Flexion contracture (2)
No flexion contracture
32, 57 (2)
Knee swelling (1)
No knee swelling
47 (1)
Radiologic leg length discrepancy (2)
Not-FACTOR
30, 90 (2)
Perception of leg length discrepancy (1)
No perception of leg length discrepancy
30 (1)
Malpositioning of femoral component (4)
Accurate coronal alignment
68 (1)
Medial malpositioned femoral component (more than 5 mm)
169 (1)
Accurate rotation
77 (1)
Not-FACTOR
129 (1)
Malpositioning of tibial component (1)
Not-FACTOR
77 (1)
Residual symptom (1)
No residual symptoms
137 (1)
Physical function (7)
Good physical function
7, 11, 36, 48, 117, 130, 137 (7)
Degree of expectation met (5)
Pre-operative expectations met
21, 22, 40, 137, 164 (5)
Anterior–posterior knee stability (1)
Not-FACTOR
152 (1)
Ligament balance (3)
Good ligament balance of the knee
58, 76, 119 (3)
Medial joint laxity (1)
No medial joint laxity
167 (1)
Lateral joint laxity (1)
Not-FACTOR
167 (1)
Noise (2)
Not-FACTOR
100, 159 (2)
Altered sensation (2)
No numbness
159 (1)
Not-FACTOR
127 (1)
Complication (3)
No complication
22, 125 (2)
No deep prosthetic infection
5 (1)
7. Surgeon and healthcare factors (11)
Type of analgesia used (1)
Not-FACTOR
173 (1)
Post-operative irrigation (1)
Continuous irrigation by cold saline with epinephrine
105 (1)
Post-operative rehabilitation (2)
Patients’ high motivation
47 (1)
Regular physical activity
28 (1)
Length of hospital stay (2)
Short hospital stay
5 (1)
Not-FACTOR
176 (1)
Waiting time before TKR (1)
Shorter than 6 months
111 (1)
Country where TKR is conducted (1)
Not-FACTOR
107 (1)
Surgeon’s job title (consultant or not) (1)
Not-FACTOR
9 (1)
Surgeon’s perspective towards the TKR (surgeon’s satisfaction) (1)
Not-FACTOR
124 (1)
Hospital choice (1)
Patients having a hospital choice
113 (1)
(Relating scores/scales) (17)
Relation (+)
WOMAC score
86, 126, 138, 164 (4)
Oxford Knee Score
37, 38, 68, 153, 156, 176 (6)
Knee Society Score
72, 176 (2)
SF-12 score
153, 176 (2)
SF-36 score
164 (1)
Control Preference Scale
50 (1)
Relation (−)
New Knee Society Score
101 (1)
Reporting studies are described using serial numbers in Table 3. The number of each category is shown in parentheses
Not-FACTOR ‘it is a factor which does NOT relate to patient satisfaction’
Fig. 2
Number of reportings in seven groups of factors for patient satisfaction following total knee replacement. Blue bar means FACTOR (‘it is a factor for patients’ satisfaction’) and orange bar means Not-FACTOR (‘it is a factor which does NOT relate to patients’ satisfaction’)
British Orthopaedic Association grading system (4)
1, 67, 75, 127
Total Knee Function Questionnaire (3)
44, 137, 141
Authors’ original questionnaire (5)
25, 26, 27, 99, 163
Unclear (1)
51
Studies are described using serial numbers in Table 3. The number of studies in each group is shown in parentheses
×
The quality of all the 181 studies was assessed and the results are shown in Tables 6, 7, 8, 9 and 10. The strength of each factor was described using the sum of percentage in each type of study (RCT, cohort study, case–control study, cross-sectional study and case series) (Fig. 3). RCTs were considered to be the strongest (deep colour in Fig. 3) and this was followed by cohort study, case–control study and cross-sectional study, respectively. Case series was considered to be the weakest (light colour in Fig. 3).
Table 6
Results of quality assessment of 181 studies—cohort studies: 93 studies. The Joanna Briggs Institute Critical Appraisal Checklist is used
Scoring: Yes = 2 / Unclear = 1 / No = 0 / NA = not applicable
Q1: Were the two groups similar and recruited from the same population?
Q2: Were the exposures measured similarly to assign people to both exposed and unexposed groups?
Q3: Was the exposure measured in a valid and reliable way?
Q4: Were confounding factors identified?
Q5: Were strategies to deal with confounding factors stated?
Q6: Were the groups/participants free of the outcome at the start of the study (or at the moment of exposure)?
Q7: Were the outcomes measured in a valid and reliable way?
Q8: Was the follow-up time reported and sufficient to be long enough for outcomes to occur?
Q9: Was follow-up complete, and if not, were the reasons to lose to follow-up described and explored?
Q10: Were strategies to address incomplete follow-up utilised?
Q11: Was appropriate statistical analysis used?
Study (serial no.)
Q1
Q2
Q3
Q4
Q5
Q6
Q7
Q8
Q9
Q10
Q11
Total ( /22)
%
1
2
2
2
1
1
2
2
2
2
1
2
19
86.4
5
1
1
2
0
0
0
2
2
2
2
2
14
63.6
6
2
2
1
1
0
2
2
2
2
2
2
18
81.8
7
0
2
2
0
0
2
2
2
2
2
2
16
72.7
10
2
2
2
2
2
1
2
2
2
2
2
21
95.5
11
0
1
2
0
0
2
2
2
2
2
1
14
63.6
12
2
2
2
0
2
2
2
2
2
1
2
19
86.4
14
0
1
1
1
1
2
2
2
2
1
2
15
68.2
16
0
0
2
0
0
1
2
2
2
2
1
12
54.5
17
0
0
2
0
0
1
2
2
2
2
2
13
59.1
18
2
2
2
0
0
2
2
2
2
1
1
16
72.7
23
1
1
2
2
2
2
2
2
2
1
2
19
86.4
28
0
2
2
2
2
2
2
2
2
1
2
19
86.4
30
0
1
1
0
0
2
2
2
2
1
2
13
59.1
32
2
2
2
1
1
2
2
2
2
1
2
19
86.4
33
0
2
2
2
2
1
2
2
1
0
2
16
72.7
34
2
2
2
2
2
2
2
2
2
0
2
20
90.9
35
0
2
2
2
2
1
2
2
1
0
2
16
72.7
36
2
2
2
1
2
1
2
2
1
1
2
18
81.8
37
0
2
2
0
0
1
2
2
2
0
2
13
59.1
39
2
2
2
0
0
1
2
2
2
0
2
15
68.2
40
0
2
2
0
0
2
2
2
2
0
2
14
63.6
41
2
2
2
2
2
2
2
2
2
0
2
20
90.9
42
2
2
2
0
0
2
2
2
2
2
1
17
77.3
44
2
2
2
2
1
2
2
2
2
0
2
19
86.4
46
2
2
2
0
0
2
2
2
2
0
2
16
72.7
49
0
2
2
1
1
2
2
2
2
1
1
16
72.7
50
0
2
2
0
0
1
2
2
1
1
2
13
59.1
51
2
2
2
0
0
2
2
2
1
0
2
15
68.2
53
0
2
2
0
0
2
2
2
2
0
2
14
63.6
54
0
2
2
0
0
2
2
2
1
0
2
13
59.1
56
2
2
2
2
2
2
2
2
2
0
2
20
90.9
57
2
2
2
0
0
2
2
2
2
0
2
16
72.7
58
2
2
2
0
0
2
2
2
1
0
2
15
68.2
59
0
2
2
0
0
2
2
2
2
0
2
14
63.6
65
2
1
2
0
0
2
2
2
2
0
2
15
68.2
66
2
2
2
2
2
2
2
2
2
1
2
21
95.5
68
0
2
2
0
0
2
2
2
1
0
2
13
59.1
70
0
2
2
1
0
2
2
2
1
0
2
14
63.6
73
0
2
2
0
0
2
2
2
2
0
2
14
63.6
74
2
2
2
1
2
2
2
2
2
0
1
18
81.8
75
2
2
2
2
2
2
2
2
2
0
2
20
90.9
79
2
2
2
2
2
2
2
2
2
1
2
21
95.5
80
2
2
2
2
2
2
2
2
2
1
2
21
95.5
81
2
2
2
0
0
2
2
1
0
0
1
12
54.5
83
2
2
2
2
2
2
2
2
2
0
2
20
90.9
85
2
2
2
1
1
2
2
2
2
0
2
18
81.8
90
2
2
2
0
0
2
2
2
2
0
2
16
72.7
94
2
2
2
0
0
2
2
2
2
0
2
16
72.7
95
2
2
2
0
0
2
2
2
2
0
2
16
72.7
99
2
2
2
0
0
2
2
2
2
0
2
16
72.7
101
0
2
2
0
0
2
2
2
1
0
2
13
59.1
104
2
2
2
2
1
2
2
2
2
2
2
21
95.5
105
2
2
2
0
0
2
2
2
2
0
2
16
72.7
107
0
2
1
1
2
2
2
2
2
0
2
16
72.7
111
2
2
2
0
1
2
2
2
2
1
2
18
81.8
112
1
2
2
0
0
2
2
2
2
0
2
15
68.2
115
2
2
2
2
2
2
2
2
1
0
2
19
86.4
116
2
2
2
0
0
2
2
2
1
0
2
15
68.2
119
0
2
2
1
1
2
2
2
2
0
2
16
72.7
121
0
2
2
2
2
2
2
2
1
0
2
17
77.3
122
2
2
2
0
0
2
2
2
1
0
2
15
68.2
124
0
1
2
0
0
2
2
2
1
0
2
12
54.5
125
0
2
1
0
0
2
2
2
2
0
2
13
59.1
126
1
1
2
1
2
2
2
2
1
0
2
16
72.7
127
1
2
2
0
0
2
2
1
1
0
1
12
54.5
128
2
2
2
0
0
2
2
2
1
0
1
14
63.6
131
2
2
2
0
0
2
2
2
2
0
1
15
68.2
132
0
2
2
2
2
2
2
2
2
1
1
18
81.8
134
1
2
2
0
0
2
2
2
2
0
1
14
63.6
135
0
2
2
0
0
2
2
2
1
0
1
12
54.5
138
1
2
2
2
1
2
2
2
2
0
2
18
81.8
139
2
2
2
2
2
2
2
2
2
1
2
21
95.5
141
2
2
2
0
0
2
2
2
1
0
2
15
68.2
142
2
2
2
0
0
2
2
2
2
0
2
16
72.7
144
2
2
2
1
0
2
2
2
2
0
2
17
77.3
145
2
2
2
2
1
2
2
2
2
2
2
21
95.5
150
2
2
2
0
0
2
2
2
2
0
2
16
72.7
151
0
2
2
0
0
2
2
2
1
0
2
13
59.1
152
0
2
2
0
0
2
2
2
2
0
2
14
63.6
153
0
2
2
1
1
2
2
2
2
0
2
16
72.7
154
0
2
2
0
0
2
2
2
2
1
2
15
68.2
155
1
2
2
1
1
2
2
2
2
0
2
17
77.3
156
0
2
2
1
1
2
2
2
2
0
2
16
72.7
157
0
2
2
0
0
2
2
2
1
0
2
13
59.1
158
2
2
2
0
0
2
2
2
2
0
2
16
72.7
160
2
2
2
0
0
2
2
2
1
0
2
15
68.2
161
2
2
2
0
1
2
2
2
2
0
2
17
77.3
163
2
2
2
0
0
2
2
2
2
0
2
16
72.7
164
0
2
2
0
0
2
2
2
1
0
2
13
59.1
170
0
2
2
1
1
2
2
2
1
0
2
15
68.2
172
2
2
2
1
1
2
2
2
2
0
2
18
81.8
175
2
2
2
0
0
2
2
2
2
0
1
15
68.2
Studies are described using serial numbers in Table 3
Table 7
Results of quality assessment of 181 studies—case–control studies: 9 studies. The Joanna Briggs Institute Critical Appraisal Checklist is used
Scoring: Yes = 2 / Unclear = 1 / No = 0 / NA = not applicableQ1: Were the groups comparable other than the presence of disease in cases or the absence of disease in controls?
Q2: Were cases and controls matched appropriately?
Q3: Were the same criteria used for identification of cases and controls?
Q4: Was exposure measured in a standard, valid and reliable way?
Q5: Was exposure measured in the same way for cases and controls?
Q6: Were confounding factors identified?
Q7: Were strategies to deal with confounding factors stated?
Q8: Were outcomes assessed in a standard, valid and reliable way for cases and controls?
Q9: Was the exposure period of interest long enough to be meaningful?
Q10: Was appropriate statistical analysis used?
Study (serial no.)
Q1
1. Q2
2. Q3
3. Q4
4. Q5
5. Q6
6. Q7
7. Q8
8. Q9
9. Q10
Total ( /20)
%
15
2
1
2
2
2
1
1
2
2
2
17
85.0
20
1
1
1
2
2
1
1
2
0
2
13
65.0
69
1
1
1
2
2
2
1
2
2
2
16
80.0
93
2
2
2
2
2
0
0
2
2
2
16
80.0
98
2
2
2
2
2
0
0
2
2
2
16
80.0
102
1
1
1
2
2
0
0
2
2
2
13
65.0
108
2
1
1
2
2
1
1
2
1
2
15
75.0
114
2
2
2
2
2
2
2
2
2
2
20
100.0
179
2
2
2
2
2
2
2
2
2
2
20
100.0
Studies are described using Serial numbers in Table 3
Table 8
Results of quality assessment of 181 studies—cross-sectional studies: 37 studies. The Joanna Briggs Institute Critical Appraisal Checklist is used
Scoring: Yes = 2 / Unclear = 1 / No = 0 / NA = not applicable
Q1: Were the criteria for inclusion in the sample clearly defined?
Q2: Were the study subjects and the setting described in detail?
Q3: Was the exposure measured in a valid and reliable way?
Q4: Were objective, standard criteria used for measurement of the condition?
Q5: Were confounding factors identified?
Q6: Were strategies to deal with confounding factors stated?
Q7: Were the outcomes measured in a valid and reliable way?
Q8: Was appropriate statistical analysis used?
Study (serial no.)
Q1
Q2
Q3
Q4
Q5
Q6
Q7
Q8
Total ( /16)
%
2
2
2
2
2
1
1
2
2
14
87.5
3
2
2
1
2
0
0
2
2
11
68.8
9
2
2
2
2
1
1
2
2
14
87.5
21
2
2
2
2
0
0
2
2
12
75.0
22
2
2
2
2
0
0
2
2
12
75.0
24
2
2
2
2
0
0
2
2
12
75.0
29
1
2
2
2
2
2
2
2
15
93.8
38
2
2
2
2
2
2
2
2
16
100.0
45
1
2
2
2
1
1
2
2
13
81.3
47
1
2
2
2
0
0
2
2
11
68.8
48
2
2
2
2
0
0
2
2
12
75.0
55
2
2
2
2
0
0
2
2
12
75.0
62
2
2
2
2
1
2
2
2
15
93.8
63
1
2
2
1
1
1
2
2
12
75.0
71
1
2
2
2
1
2
2
2
14
87.5
72
1
2
2
2
0
0
2
2
11
68.8
77
1
1
2
2
0
0
2
2
10
62.5
86
2
2
2
2
0
0
2
2
12
75.0
89
2
2
2
2
0
0
2
2
12
75.0
100
2
2
2
2
0
0
2
2
12
75.0
106
2
2
2
2
0
0
2
2
12
75.0
113
2
2
2
2
0
2
2
2
14
87.5
117
2
2
2
2
2
2
2
2
16
100.0
118
2
2
2
2
0
0
2
2
12
75.0
130
2
2
2
2
0
0
2
2
12
75.0
133
2
2
2
2
2
2
2
2
16
100.0
136
2
2
2
2
0
0
2
2
12
75.0
137
1
2
2
2
0
0
2
2
11
68.8
146
1
2
2
2
0
0
2
2
11
68.8
147
2
2
2
2
1
2
2
2
15
93.8
149
0
2
2
2
0
0
2
2
10
62.5
159
1
2
2
2
0
0
2
2
11
68.8
162
1
2
2
2
1
2
2
2
14
87.5
167
2
2
2
2
0
0
2
2
12
75.0
169
2
2
2
2
0
0
2
2
12
75.0
171
2
2
2
2
0
0
2
2
12
75.0
176
2
2
2
2
0
0
2
2
12
75.0
Studies are described using serial numbers in Table 3
Table 9
Results of quality assessment of 181 studies—case series studies: 2 studies. The Joanna Briggs Institute Critical Appraisal Checklist is used
Scoring: Yes = 2 / Unclear = 1 / No = 0 / NA = not applicable
Q1: Were there clear criteria for inclusion in the case series?
Q2: Was the condition measured in a standard, reliable way for all participants included in the case series?
Q3: Were valid methods used for identification of the condition for all participants included in the case series?
Q4: Did the case series have consecutive inclusion of participants?
Q5: Did the case series have complete inclusion of participants?
Q6: Was there clear reporting of the demographics of the participants in the study?
Q7: Was there clear reporting of clinical information of the participants?
Q8: Were the outcomes or follow-up results of cases clearly reported?
Q9: Was there clear reporting of the presenting site(s)/clinic(s) demographic information?
Q10: Was statistical analysis appropriate?
Study (serial no.)
Q1
1. Q2
1. Q3
1. Q4
1. Q5
1. Q6
1. Q7
1. Q8
1. Q9
10. Q10
Total ( /20)
%
76
1. 2
2. 2
2. 1
2. 1
1. 2
1. 2
1. 2
1. 1
2. 2
11. 2
17
85.0
181
2. 2
3. 2
3. 2
3. 2
2. 2
2. 2
2. 2
2. 2
3. 2
12. 2
20
100.0
Studies are described using serial numbers in Table 3
Table 10
Results of quality assessment of 181 studies—randomised controlled trials: 40 studies. A modified version of critical appraisal checklist by van Tulder et al [15] is used
Scoring: Yes = 2 / Unclear = 1 / No = 0 / NA = not applicable
Q1: Acceptable method of randomisation
Q2: Concealed treatment allocation
Q3: Similar group values at baseline
Q4: Blinded assessor
Q5: No or similar co-interventions
Q6: Acceptable compliance (≥ 75%)
Q7: Acceptable drop-out rate (≤ 30%)
Q8: Similar timing of the outcome assessment in all groups
Q9: Intention to treat analysis
Study (serial no.)
Q1
Q2
Q3
Q4
Q5
Q6
Q7
Q8
Q9
Total ( /18)
%
4
2
2
2
2
2
2
2
2
0
16
88.9
8
2
2
2
2
2
2
2
2
2
18
100.0
13
2
2
2
2
2
2
2
2
0
16
88.9
19
2
2
2
2
2
2
2
2
0
16
88.9
25
2
2
2
2
2
2
0
2
0
14
77.8
26
2
2
2
2
2
1
1
2
0
14
77.8
27
2
2
2
2
2
1
0
2
0
13
72.2
31
2
1
2
2
2
2
2
2
2
17
94.4
43
2
2
2
2
2
2
2
2
0
16
88.9
52
1
1
2
0
2
2
2
2
0
12
66.7
60
2
2
2
2
2
2
2
2
0
16
88.9
61
1
1
2
2
2
1
0
2
0
11
61.1
64
1
1
2
0
2
2
2
2
0
12
66.7
67
2
2
2
2
2
2
2
2
0
16
88.9
78
1
1
1
0
2
2
2
2
0
11
61.1
82
2
2
2
2
2
2
2
2
0
16
88.9
84
2
2
2
0
2
2
2
2
0
14
77.8
87
2
1
2
1
2
2
2
2
0
14
77.8
88
1
1
2
2
2
2
2
2
0
14
77.8
91
2
2
2
2
2
2
2
2
0
16
88.9
92
2
2
2
0
2
2
2
2
0
14
77.8
96
2
1
2
0
2
2
2
2
2
15
83.3
97
2
1
2
0
2
2
2
2
0
13
72.2
103
2
1
2
2
2
2
2
2
0
15
83.3
109
2
0
2
0
2
2
2
2
0
12
66.7
110
2
1
2
2
2
2
2
2
0
15
83.3
120
1
1
2
2
2
2
2
2
0
14
77.8
123
2
1
2
2
2
2
2
2
0
15
83.3
129
2
1
2
2
2
2
2
2
0
15
83.3
140
2
1
2
2
2
2
2
2
0
15
83.3
143
2
1
2
2
2
2
2
2
0
15
83.3
148
2
2
2
2
2
2
2
2
0
16
88.9
165
2
2
2
2
2
2
2
2
0
16
88.9
166
2
1
2
2
2
2
2
2
0
15
83.3
168
2
1
2
2
2
2
2
2
0
15
83.3
173
1
1
2
2
2
1
1
2
0
12
66.7
174
2
1
2
2
2
1
1
2
0
13
72.2
177
2
2
2
2
2
2
2
2
0
16
88.9
178
1
1
2
1
2
1
1
2
0
11
61.1
180
2
2
2
2
2
2
2
2
2
18
100.0
Studies are described using serial numbers in Table 3
Fig. 3
Sum of percentage from full score (%) based on the quality assessment in each type of study for each factor. Blue bar means FACTOR (‘it is a factor for patients’ satisfaction’) and orange bar means Not-FACTOR (‘it is a factor which does NOT relate to patients’ satisfaction’). a Patients’ demographical factors. b Patients’ non-knee factors. c Patients’ knee factors. d Factors of implants/prostheses. e Intra-operative technical factors. f Post-operative outcome factors. g Surgeon and healthcare factors
×
When the results of the quality assessment were taken into consideration, a negative history of mental health problems, use of a mobile-bearing insert, patellar resurfacing, severe pre-operative radiological degenerative change, negative history of low back pain, no/less post-operative pain, good post-operative physical function and pre-operative expectations being met were considered to be important factors. Significant factors affecting patient satisfaction are summarised in Tables 11, 12 and 13.
Table 11
List of frequently reported factors as FACTOR (‘it is a factor for patient satisfaction’)
Factors (number of reportings)
1st place
No mental health problems (13 reportings)
2nd place
No/less post-operative pain (7 reportings)
2nd place
Good post-operative physical function (7 reportings)
4th place
Improvement in ROM (6 reportings)
5th place
Normal BMI (5 reportings)
5th place
Pre-operative expectations met (5 reportings)
BMI body mass index, ROM range of motion
Table 12
List of factors which have the highest sum of percentage score (a percentage from full score) of FACTOR (‘it is a factor for patient satisfaction’) only based on the quality assessment for various combination of the types of the studies
RCT
RCT
+ Cohort
RCT
+ Cohort
+ Case–control
RCT
+ Cohort
+ Case–control
+ Cross-sectional
RCT
+ Cohort
+ Case–control
+ Cross-sectional
+ Case series
1st place
Use of mobile bearing insert (261.1%)
No mental health problems (672.6%)
No mental health problems (672.6%)
No mental health problems (885.2%)
No mental health problems (885.2%)
2nd place
Patellar resurfacing (238.9 %)
Use of mobile-bearing insert (347.5%)
Use of mobile bearing insert (347.5%)
No/less post-operative pain (561.5%)
No/less post-operative pain (561.5%)
RCT randomised controlled trial
Table 13
List of factors which have the highest sum of percentage score (a percentage from full score) of FACTOR (‘it is a factor for patient satisfaction’) and Not-FACTOR (‘it is a factor which does NOT relate to patient satisfaction’) based on the quality assessment for all type of the studies
Factors (% score)
1st place
No mental health problems (739.8%)
2nd place
No/less post-operative pain (561.5%)
3rd place
Good physical function (536.9%)
4th place
Pre-operative expectations met (341.5%)
5th place
Severe pre-operative radiographic degenerative change (301.2%)
6th place
No low back pain (240.9%)
Percentage score of Not-FACTOR was calculated as negative value
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Discussion
The dissatisfaction rate following a TKR remains around 20% and is a constant source of frustration for the patient and the surgeon [11, 12]. Our study has systematically reviewed all the articles looking at satisfaction following a TKR to determine the factors, which could be responsible for this issue. Several factors were deemed to be important in affecting patient satisfaction based on the number of studies in which they were reported as well as the results of the quality assessment of the study (Tables 11, 12 and 13).
Negative history of mental health problems
A negative history of mental health problems was the most frequently reported factor affecting patient satisfaction (Table 11) and also scored the highest sum of percentage of FACTOR based on the quality assessment for RCT + cohort study (± case–control study ± cross-sectional study ± case series study) (Table 12). In addition, it was ranked first in terms of the highest sum of percentage of FACTOR and Not-FACTOR based on the quality assessment for all types of the studies (Table 13). Depressive symptoms and anxiety were reported to be predictive of long-term pain and functional impairment as measured by the Knee Society Score in 83 patients at 5 years [16]. In addition, it was reported that pre-operative anxiety/depression is an independent risk for severe post-operative pain and may explain as to why there is a subset of patients with unexplained pain after surgery [17]. Moreover, Macleod et al. report that patients with mental disability suffered a greater level of comorbidity and were socially deprived, which is also related to poorer physical health which then has an impact on satisfaction [18]. Finally, another study reported that patients with poor mental health, which can impair coping mechanisms for pain, might present with less severe disease, and this could also influence their satisfaction [19].
Use of a mobile-bearing insert
The use of a mobile-bearing insert had the highest sum of percentage of FACTOR based on the quality assessment for RCTs. Also, it had the second highest sum of percentage of FACTOR based on the quality assessment for RCT + cohort study (± case–control study) (Table 12). The rationale behind the design of a mobile-bearing insert is to solve the kinematic conflict between low-stress articulation and free axial femoral–tibial rotation by allowing rotation of a highly conforming polyethylene insert [20]. Theoretically, the design of the mobile-bearing insert could lead to better ROM especially during flexion [21]. A greater loss of flexion was reported after 12 months in patients with a TKR with a fixed-bearing prosthesis in comparison with a mobile-bearing prosthesis [22]. It is quite intuitive to comprehend that a good post-operative ROM relates to patient satisfaction, and our results support this (improvement in ROM was the 4th most frequently reported factor for patient satisfaction). Kim et al. suspect the low constraint of mobile-bearing insert may restore normal kinematics of the knee and it contributes to favourable clinical outcomes compared with a fixed-bearing insert [23]. Price et al. in a prospective multicentre trial of 39 simultaneous bilateral procedures also found that patients with a mobile-bearing insert had significantly better clinical results than patients with a fixed-bearing insert [21].
Patellar resurfacing
Patellar resurfacing has the second highest sum of percentage of FACTOR based on the quality assessment for RCTs (Table 12). Four studies showed patients with patella resurfacing were more satisfied than those without it [11, 24‐26]. Amongst them, one study focused on only knees with no exposed bone on the undersurface of the patella to determine the potential advantages of leaving the patella non-resurfaced [25]. Dissatisfaction in patella non-resurfaced patients may be due to the higher rate of post-operative anterior knee pain, and patients whose patella was not resurfaced at the index TKR tended to have a higher revision rate as well [25‐28]. However, it should be noted that this issue may be strongly related to the design of the implant. There have also been abundant literature that showed that the patellofemoral design in TKR is critical and can vary the forces on the patellofemoral joint as well as patellofemoral tracking [29‐31]. Two of the 4 studies relate to a specific prosthesis (PFC) which is notoriously patella unfriendly [25, 26], so this relationship may therefore not necessarily hold true for the newer implants with patella-friendly designs.
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Severe pre-operative radiological degenerative change
Severe pre-operative radiological degenerative change has the fifth highest sum of percentage of FACTOR and Not-FACTOR based on the quality assessment for all types of studies (Table 13). Although the classic indication for replacing a patient’s knee is end-stage arthritis (Kellgren–Lawrence grade IV [32]), there are a number of patients who have a TKR much before grade IV radiological changes have set in and it is dependent on the symptoms of the patient. The individual indication is complex and involves multiple factors [33]. Patients with mild pre-operative OA were reported to have a worse prognosis in improvement in physical functioning [34, 35], and therefore, it is difficult to meet their expectations post-operatively [35]. These effects are more noticeable in patients undergoing a TKR as compared with those who have had a THR [34]. The knee is a complex joint and the biomechanics of this joint are much more difficult to replicate with a prosthetic knee as compared with a prosthetic hip which may partly explain a smaller increase in physical functioning and a poor rate of satisfaction in patients with mild OA having a TKR [36].
No low back pain
No low back pain has the sixth highest sum of percentage of FACTOR and Not-FACTOR based on the quality assessment for all types of the studies (Table 13). The prevalence of chronic low back pain in the UK has been reported to range from 6 to 11% [29], and this is increased to 55% in patients with OA of the knee [30]. Furthermore, low back pain has been demonstrated to be three to four times more likely to be present in patients with a history of depression [37]. Also, patients with chronic low back pain have a higher rate of musculoskeletal and neuropathic pain conditions, depression, anxiety and sleep disorders [31]. In addition, patients with low back pain reported to have more symptoms from their osteoarthritic knee which may suggest a lower threshold for pain in this cohort leading to dissatisfaction [30].
Normal BMI
Normal BMI was the fifth most frequently reported factor for patient satisfaction (Table 11). BMI greater than 30 kg/m2 was reported to be associated with a higher rate of revision and poorer functional outcomes as well which again contributes to dissatisfaction [38]. In addition, morbidly obese patients are likely to suffer from wound problems, ligament injuries and infections peri-operatively which lead to dissatisfaction [22]. Another study showed that despite lower pre- and post-operative WOMAC and SF-36 scores, obese patients experienced similar improvements compared with non-obese patients, although levels of satisfaction in the obese group were lower than those in the non-obese group [39]. The authors stated that one explanation for this might be that satisfaction was more closely associated with the absolute post-operative functional level rather than the magnitude of any improvement, as the rate of satisfaction mirrored absolute values of post-operative WOMAC and SF-36 scores.
Other factors
Other than factors discussed in the previous section, no/less post-operative pain, good post-operative physical function, improvement in ROM and pre-operative expectations being met were considered to be important for patient satisfaction based on the number of reportings and the results of quality assessment (Tables 11, 12 and 13). TKR is a painful procedure and it does take at least six to 12 months to get the maximum benefit from this procedure [40], and therefore, setting realistic expectations with the patient in the pre-operative clinic is essential to avoid dissatisfaction.
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Limitations and strengths of the study
Our study has several limitations. Firstly, the method of measuring satisfaction is different in each study, and therefore, a uniform way of assessing satisfaction is essential for the orthopaedic community. Secondly, the timing of assessment of satisfaction after the index TKR varied amongst studies and this again requires standardisation. Thirdly, in many of the studies included in this review, the authors have only focused on one factor and the mutual or overall effect of multiple factors was not assessed. Fourthly, no statistical tests of intra-class correlation coefficients, inter-rater reliability and heterogeneity amongst the studies were performed in this systematic review. Finally, there are several studies in which patients are duplicated amongst studies and our review was limited to publications in English, so there is a possibility of publication bias.
However, despite all these limitations, the main strength of this study lies in its broad and comprehensive initial literature search as well as complete and in-depth quality assessment for each study and the factors. We have determined all the factors which could potentially affect patient satisfaction following a TKR which have been reported in the literature thus far.
Conclusion
No history of mental health problems, use of a mobile bearing insert, patellar resurfacing, severe pre-operative radiological degenerative change, no low back pain, normal BMI, no/less post-operative pain, good physical function post-operatively, improvement in ROM and pre-operative expectations being met were considered to be significant factors leading to better patient satisfaction following a TKR.
Surgeons performing a TKR should take these factors into consideration prior to deciding whether a patient is suitable for a TKR. Secondarily, a detailed explanation of these factors should form part of the process of informed consent to achieve better patient satisfaction following TKR.
There is great need for a unified approach to assessing satisfaction following a TKR and also the time at which satisfaction is assessed.
Moreover, further studies and ideally larger RCTs focusing on each of these factors are required to determine the exact correlation of these factors with satisfaction.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
Ethical approval
This article does not contain any studies with human participants or animals performed by any of the authors.
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