Cross-sectional study of pain and disability at knee replacement surgery for osteoarthritis in 299 patients

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Joint Bone Spine 74 (2007) 612e616 http://france.elsevier.com/direct/BONSOI/

Original article

Cross-sectional study of pain and disability at knee replacement surgery for osteoarthritis in 299 patients Florence Merle-Vincent a,*, Chantal M. Couris b, Anne-Marie Schott b, Marie Perier a, Sylvie Conrozier a, Thierry Conrozier a, Muriel Piperno a, Pierre Mathieu a, Eric Vignon a a

Rheumatology Department, Pavilion 2B, Lyon-South Hospital Center, 69495 Pierre Be´nite, France b Medical Information Department, Lyon, France Received 24 August 2006; accepted 9 January 2007 Available online 13 August 2007

Abstract Objective: To evaluate pain and disability at the time of knee replacement surgery for osteoarthritis. Methods: In this multicenter cross-sectional study, 299 patients at 12 orthopedic surgery centers in Lyon, France were evaluated on the day before knee replacement surgery. Pain severity was assessed on a visual analog scale (VAS) and function using the Lequesne index and the Western Ontario McMaster Universities Osteoarthritis Index (WOMAC). Results: There were 207 women and 92 men with a mean age of 73 years. Mean (SD) VAS pain score upon walking was 55.8  24 mm. Compared to patients with very severe disability (Lequesne index > 12), those with mild-to-severe disability (Lequesne index  12) were more likely to be older than 70 years (odds ratio [OR], 2.85; 95% confidence interval [95%CI], 1.25e5) and male (OR, 2.5; 95%CI, 1.3e5); they were less likely to have a body mass index > 27 kg/m2 (OR, 2.2; 95%CI, 1.3e3.3) and to engage in sporting activities (OR, 3.3; 95%CI, 1.4e10). Conclusion: Patients about to undergo knee replacement surgery had high levels of pain and disability, with little variation across centers. Nevertheless, the severity of pain and disability may depend in part on age, gender, body mass index, and sporting activities, which probably influence the decision to perform knee replacement surgery. Ó 2007 Elsevier Masson SAS. All rights reserved. Keywords: Knee; Osteoarthritis; Total knee replacement; Lequesne index; WOMAC index

1. Introduction Knee osteoarthritis is an extremely common condition. The standardized incidence rate is estimated at 24/10,000 personyears overall and increases gradually with age, reaching 10/ 1000 person-years in women aged 70e79 years [1]. Prevalence estimates after 70 years of age range from 20% to 50% according to the criteria used to define knee osteoarthritis [2,3]. Total knee replacement (TKR) is a satisfactory treatment for advanced incapacitating knee osteoarthritis, with success rates of 50e100% in terms of pain and function [4,5]. However, most studies of TKR outcomes exhibit methodological * Corresponding author. Tel.: þ33 478861688. E-mail address: [email protected] (F. Merle-Vincent).

weaknesses such as failure to use validated scales to assess pain, function, and quality of life [7e9]; or failure to obtain preoperative data for comparison. The complication rate is unclear, about 18% on average [10]. There is no consensus about the indications for TKR or the optimal approach to outcome evaluation. Factors identified by research studies or experts as influencing the decision to perform TKA include the algofunctional index for pain and disability [7,11e13], body mass index, age, and the psychological and social setting [14,15]. In addition, the characteristics of the healthcare system [7] or physician [11,16] may affect surgical decisions. To date, there are no international recommendations on the indications for TKA. Despite the absence of universally accepted indications, TKA is being increasingly performed. In the USA, a 3-fold

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F. Merle-Vincent et al. / Joint Bone Spine 74 (2007) 612e616

increase between 1990 and 2002 was reported [17]. Here, our primary objective was to evaluate pain severity and disability in patients about to undergo TKA in France. To this end, we used two validated measurement tools, the Lequesne index and the Western Ontario McMaster Universities Osteoarthritis Index (WOMAC). Our secondary objective was to identify factors associated with TKA in patients with moderate pain and disability (Lequesne index  12). 2. Methods 2.1. Study design We conducted a multicenter, prospective, cross-sectional, descriptive study in patients who met three inclusion criteria: knee osteoarthritis meeting American College of Rheumatology (ACR) criteria [18], scheduled TKA, and availability of at least one anteroposterior or schuss-view radiograph of the affected knee. Exclusion criteria were osteoarthritis of the target knee secondary to inflammatory joint disease, Paget’s disease of bone, pyogenic or tuberculous arthritis, osteonecrosis of the target knee, isolated chondrocalcinosis of the target knee without osteoarthritis, symptomatic hip osteoarthritis on the same side as the target knee, and unwillingness or inability of the patient to complete the study questionnaire. The nationwide hospital database was searched for healthcare facilities in the Rhoˆne district of France that admitted more than 30 patients per year for TKA. Of 14 facilities (with 30 surgeons) that met this criterion, 13 (with 23 surgeons) accepted to participate in the study. Patients were included prospectively over a 1-year period. Each week, three centers were selected at random, and all patients meeting the inclusion criteria in those centers over the week were invited to participate; centers with no TKA procedures scheduled for that week were replaced. In each patient, the study questionnaire was completed on the day before TKA. 2.2. Study data The following data were collected for each patient: age and gender, body mass index (BMI), pain severity (100-mm visual analog scale [VAS], function (Lequesne index [19,20] and WOMAC [21,22] item scores on VASs), radiographic findings (including site of greatest joint space narrowing in the target knee), disease duration, prior treatment for osteoarthritis, whether the patient had depression, history of sporting activities, occupation, whether the healthcare facility was public or private, and whether the person who decided to seek advice about TKA (called ‘‘the referrer’’ hereafter) was the patient, a general practitioner, a rheumatologist, or a physician in another specialty. The data were recorded by a study nurse who was independent from the healthcare centers participating in the study. The nurse completed a questionnaire during an interview with the patient, asked the patient to complete a self-administered questionnaire, and took digital photographs of the anteroposterior and/or schuss-view radiographs

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of the target knee, as well as of the contralateral knee where available. The radiographs were read by an experienced physician who was unaware of patient data. A schuss view was available for only 129 patients; therefore, we used the anteroposterior view where available (285/299 patients) and the schuss view otherwise (14 patients). The absence of exclusion criteria such as aseptic osteonecrosis and isolated chondrocalcinosis was checked. The osteophyte score was determined as follows: 0, no osteophytes; 1, possible osteophytosis; 2, definite osteophytosis; and 3, severe osteophytosis. Joint space narrowing was assessed on the 6-point Piperno and Vignon scale (0, none; 1, possible; 2, definite; 3, joint space equal to less than one-third of the width in the contralateral knee; 4, joint space obliteration; and 5, bony erosions) [23]. 2.3. Statistical analysis Descriptive statistics were computed. Box-and-whisker plots were drawn to display pain, Lequesne, and WOMAC scores. Box-and-whisker plots depict the distribution of quartiles, the range, and the outlying values. For further statistical evaluation, we divided patients into two groups based on each of four variables: age (70 years and >70 years), BMI (27 kg/m2 and >27 kg/m2), Lequesne score (12 and >12, the cutoff used by Lequesne to indicate a need for TKA [19]), and narrowing score (3 or >3). Univariate analysis with the Lequesne score as the dependent variable was conducted using Chi-square tests and Student’s tests. Variables with P-values 0.20 by univariate analysis were introduced into a multivariate logistic regression model, together with a number of variables selected by experts. Variables in the model included age, gender, BMI, narrowing score, referrer, depression, sporting activities, and history of contralateral TKA. For each variable, the odds ratio (OR) and its 95% confidence interval (95%CI) were computed. All statistical tests were carried out using SPSS version 11.5.1 (SPSS Inc, Chicago, IL) [24]. 3. Results We included 301 patients, of whom two were excluded, because of avascular osteonecrosis and poor-quality radiographs, respectively. Of the 12 centers that recruited patients to the study, six included more than 20 patients each and three more than 35 patients each; two of these three centers were public hospitals and one was a private center with two orthopedic surgeons. Median age of the 299 study patients was 74 years (range, 48e93 years). Of the 231 (77%) patients who were overweight (BMI > 25 kg/m2), 99 (99/299, 33%) were obese (BMI > 30 kg/m2) (Table 1). The interquartile range (Q1eQ3) was 37e70 mm for overall pain and 39e75 mm for pain upon walking (Fig. 1 and Table 2). The Lequesne index was greater than 12 in 231 (77% patients) and greater than 10 in 239 (80%) patients. Median Lequesne score was 14.5 (Fig. 1 and Table 2). The mean Lequesne score

F. Merle-Vincent et al. / Joint Bone Spine 74 (2007) 612e616

614 Table 1 Main characteristics of the 299 study patients

Age BMI Time with occasional pain (years) Time with pain every day (years)

Female gender Depression Paid employment Current athletic activities Previous high-level athletic activities Prior surgery on the target knee Contralateral TKA Medial femorotibial OA on radiographs Chondrocalcinosis Narrowing score >3 Osteophytosis score >1 Contralateral osteoarthritis on radiographs First physician seen General practitioner Rheumatologist Other Unknown Referrer Patient General practitioner Rheumatologist Other Healthcare facility Public Private

Table 2 Pain and disability on the day before surgery Mean

SD

73.2 28.4 12.2 3.5

7.9 4.4 11 4.3

Number of patients

Percentage

207 105 22 36 44 52 42 220 25 285 281 131

69 35 7 12 15 17 14.1 73.5 8.3 95.3 94 43.8

129 98 57 15

43.1 32.8 19.1 5

145 60 68 26

48.5 20.1 22.7 8.7

131 168

43.8 56.2

for symptoms while walking indicated a walking distance of about 500 m. Radiographic findings are reported in Table 1. Radiographs were available for the contralateral knee in 212 (71%) patients.

Lequesne index

Treatments during the last year consisted of analgesics in 233 (78%) patients, nonsteroidal antiinflammatory drugs in 165 (55%) patients, intraarticular hyaluronic acid injection in 59 (19.7%) patients, and intraarticular glucocorticoid injections in 68 (22.7%) patients. Referrers are reported in Table 1. The Lequesne index was >12 in 231 (77%) patients and 12 in 68 (23%) patients. Table 3 reports mean Lequesne and WOMAC values in these two groups. Factors independently associated with the Lequesne index in the multivariate model (Table 4) were age, gender, BMI, current sporting activities, and whether the healthcare facility was public or private. Patients in the less severe disability group (Lequesne index  12) were older (OR, 2.85 for age >70 years; 95%CI, 1.25e5) and more likely to be male (OR, 2.5; 95%CI, 1.3e 5); they were more likely to have a BMI  27 kg/m2 (OR, 2.2; 95%CI, 1.3e3.3) and to have no sporting activities (OR, 3.3; 95%CI, 1.4e10). Patients in the severe disability group (Lequesne index > 12) were more likely to be younger than 70 years of age, female, and markedly overweight or obese (BMI > 27 kg/m2); they were also more likely to engage in sports. TKA in a public healthcare facility was significantly associated with having a Lequesne index  12. Pain and function at surgery were not significantly associated with the narrowing score, history of contralateral TKA, depression, or referrer.

Our data on the epidemiology of TKA and on the severity of pain and functional impairment in patients selected for

20

Table 3 Mean Lequesne and WOMAC scores in the groups of patients with Lequesne index values 12 or >12

0

0 WOMAC Index

VAS for pain while walking

Mean (SD)

100 80 60

60

(25) (22) (1.4) (2) (1.3) (3.5) (20) (26) (20) (19)

4. Discussion

40

10

80

55.8 54.1 5.2 3.75 5.3 14.3 52 51.8 50.1 51.3

80 60

100

VAS score for pain while walking (0e100 mm) VAS score for overall pain (0e100 mm) Lequesne pain score (0e8) Lequesne walking score (0e8) Lequesne function score (0e8) Lequesne index (0e24) WOMAC A (0e100 mm) WOMAC B (0e00 mm) WOMAC C (0e100 mm) Total WOMAC score (0e100 mm)

VAS for overall pain 100

20

Mean (SD)

40

40

20

20

0

0

Fig. 1. Pain and disability just before knee replacement surgery.

Lequesne pain score Lequesne walking score Lequesne function score Lequesne index WOMAC A WOMAC B WOMAC C Total WOMAC score

Lequesne index  12 (68 patients)

Lequesne  12 (231 patients)

3.8 2 4 9.9 3.6 3.5 3.2 3.3

5.6 4.3 5.8 15.7 5.7 5.8 5.6 5.6

(1.2) (1.1) (1.1) (1.6) (1.6) (2.4) (1.5) (1.5)

(1.1) (1.7) (1) (2.5) (1.8) (2.5) (1.7) (1.6)

F. Merle-Vincent et al. / Joint Bone Spine 74 (2007) 612e616 Table 4 Factors independently associated with a Lequesne index  12 by multivariate logistic regression (in bold type)

Male gender Public healthcare facility Age, <70 years BMI, >27 kg/m2 Sporting activities Narrowing score <3 Contralateral TKA Depression Referrer (rheumatologist was the reference) Patient General Practitioner Other

Odds ratio (95%CI)

P-value

2.5 2.04 0.35 0.45 0.3 1.05 0.6 1.18 1 1.7 0.8 1.4

(1.3e5) (1.1e3.3) (0.2e0.8) (0.3e0.8) (0.1e0.7) (0.6e2) (0.5e3.1) (0.6e2.5)

0.005 0.02 0.009 0.01 0.005 NS NS NS

(0.8e3.3) (0.2e3.3) (0.5e3.3)

NS NS NS

BMI: body mass index; TKA: total knee arthroplasty.

TKA are consistent with earlier reports. The original feature of our study is that patient characteristics were studied according to the Lequesne index just before surgery. A minority (68/299, 23%) of our patients had a Lequesne index  12. Factors significantly associated with having a Lequesne index  12 at surgery were male gender and age older than 70 years. Neither variable was significantly associated with TKA outcomes in earlier studies [13,15,25]. Female gender was associated with worse functional disability among a population of Australian patients on a TKA waiting list [26]. In our population, patients in the group with less severe disability (Lequesne index  12) were 2.2 times more likely to have a BMI  27 kg/m2, compared to the group with a Lequesne index > 12. Poorer outcomes were reported after TKA in obese patients (BMI > 30 kg/m2), compared to nonobese patients [27]. Therefore, in patients with high BMI values, surgeons may consider TKA only when marked disability develops. Patients in the less severely disabled group were less likely to engage in sports. Some sports are best avoided after TKA, whereas knee osteoarthritis does not require discontinuation of regular participation in sports that do not carry a risk of injury [28]. Therefore, surgeons may postpone TKA as long as the patient engages in sports. The nature of the referrer was not associated with milder disability (Lequesne score < 12) at surgery. This finding suggests that the final decision to perform TKA may be based on standardized pain and disability criteria. However, two studies found marked variability across physicians regarding indications for knee replacement, with only three criteria being used by all three physician categories (general practitioners, specialist physicians, and orthopedic surgeons) [11,16]. However, both studies relied on physician-reported data rather than on observation. The Lequesne index reflects pain, walking distance, and function. Similarly, the WOMAC score assesses pain, stiffness, and function during selected activities of daily living. Both tools ignore a number of exogenous factors (e.g., social status, occupation, and history of osteotomy or other surgical procedures) and may underestimate a number of deficiencies. Thus, surgeons may decide that TKA is in order despite a relatively low Lequesne index.

615

Depression is not consistently recorded in studies of patients with knee osteoarthritis. In our population, 35% of patients had self-reported depression. In a study conducted in France in community-dwelling patients aged 65 years or older, only 17.2% of patients reported anxiety and/or depression, although the questionnaire was different from the one used in our study [29]. A significant association has been reported between greater functional impairment and presence of symptoms of depression [30,31]. In one study, the prevalence of depression was increased 5-fold among patients on a waiting list for TKA, compared to a control population [26]. These data may explain the high prevalence of self-reported depression in our population. A large proportion of patients (about 50%) requested TKA, in both disability groups. Other studies found that patient request was a major criterion for deciding to perform TKA. For instance, a study from the UK [32] showed that the number of TKA procedures performed was only about half the number needed according to New Zealand criteria [5] but that this difference decreased substantially when patient willingness to undergo TKA was considered. Pain and function are the main criteria used by surgeons [8,11], panels of experts [7,13], and patients [33] to determine whether TKA is in order. In our study, pain and function were assessed chiefly using the Lequesne index. The mean value of 14.5 indicated severe pain and disability with a walking distance of about 500 m. Lequesne recommended TKA in patients whose Lequesne index was 12 but this study used >12?? [19]. In our study, 70% of patients had Lequesne index values above this threshold. Mean pain severity according to the WOMAC score was consistent with earlier studies; for instance the mean value was 53.1 in a study from Indiana [6] and 52 in our study; corresponding values for the WOMAC function score were 54 [6] and 50.1. Orthopedic surgeons recommend TKA for patients who have severe radiographic damage [7,11]. In our study, obliteration of the medial or lateral joint space was noted in 73% of patients and a narrowing score 2 in less than 5% of patients. Thus, nearly all our patients about to undergo TKA had severe clinical and radiographic knee osteoarthritis. Age and gender data in our population are consistent with earlier reports [9,13e15]. Mean BMI, however, was lower than in many studies. In the population from Indiana, for instance, mean BMI was 30.2 [6]; however, higher BMI values are typically found in the USA than in France. The marked uniformity of our population may indicate practice uniformity and/or selection bias. Of the 12 centers, three included nearly 70% of the patients. However, the distribution of patient numbers per center reflected the number of TKA procedures performed annually in each center. Thus, the three centers that included more than 35 patients each were the three centers with more than 35 TKA procedures per year. In conclusion, the patients in our study had severe pain and disability at the time of TKA. They are currently enrolled in a 2-year study of satisfaction after TKA. Factors predicting greater satisfaction will be sought in an effort to assist in developing recommendations for TKA in patients with knee osteoarthritis in France.

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