Pain and depression often coexist in medical practice. Sometimes depression occurs as a result of painful symptoms; however, chronic pain can also be a symptom of depression or increased by it.

This association poses a challenge for physicians, because the symptoms of the two entities can be confused, it being difficult to establish which of the two phenomena – depression or chronic pain – preceded the other, making an adequate therapeutic approach impossible or forcing this patient to do the rounds of the different specialists.

These patients whose primary complaint is pain, relatively often also suffer from a baseline depressive disorder, diagnosed or otherwise, and can be unfairly accused of scrounging, demanding and manipulating.

Joint replacement surgery is a proven procedure to treat pain in osteoarthritis of the knee that includes in its objectives improving quality of life.1–3

On reviewing the results of knee arthroplasty (TKA), a significant proportion of patients are observed – up to 20% in some series – in whom the persistence of chronic pain, disability, low quality of life and dissatisfaction cannot be explained by defects in the surgical technique or the implant.4

Preoperative mental health has been related to the results of TKA.5,6 Specifically, anxiety and depression prior to the surgical intervention have been described as factors associated with poorer outcomes after TKA. On the other hand, the literature also shows a decrease and therefore improvement in anxiety and depression rates in many patients following surgery.7–9

Because TKA is a procedure that can improve quality of like and increase the psychological wellbeing of patients by reducing levels of anxiety and depression, it is surprising that at the same time anxiety and depression have been considered predictors of poorer outcomes following TKA. Our hypothesis is that patients with anxiety and depression can achieve good outcomes after TKA through mental and physical improvement.

The principal aim of this study was to analyse the influence of preoperative anxiety and depression on TKA outcomes. The secondary aim was to evaluate the response that this surgical procedure might have on levels of anxiety and depression.

From an initial sample of 265 patients, 5 patients were excluded, as previously mentioned. The final sample comprised 260 patients. Of these, 74.2% (n=193) were female and 25.8% (n=67) were male. The mean age was 70.8 years, and 83% of the patients were over 65 years old. There was no difference in laterality. Of the patients, 9.6% had documented treatment for anxiety and 8.8% for depression. These patients were not excluded from the study. The most relevant clinical characteristics of the sample are shown in Table 1.

The number of patients with anxiety before the intervention was 68 and dropped to 42 at one year. With regard to depression, the total number of depressed patients was 35, and at one year it had fallen to 18. The mean score for preoperative anxiety was 7.63 and fell to 5.96 following the surgery. The mean preoperative depression score was 6.55 and had decreased at the annual check-up to 4.96.

The differences between preoperative levels of anxiety and depression and those obtained after surgery were statistically significant (P<.001) (Table 2).

The HADS classifies patients as case (clearly anxious or depressed), doubtful (with some symptoms of anxiety or depression) and non-case (without anxiety or depression).

A total of 51 patients with some symptoms of anxiety improved. Of these, 26 were clearly anxious. The remaining 25 corresponded to the partial anxiety symptomatology group (P<.001) (Fig. 1).

Fig. 1.

Evolution of anxiety. A reduction can be observed in the number of patients with anxiety (cases) at the annual check-up.

HAD: Hospital Anxiety and Depression questionnaire.

(0.08MB).

A total of 46 patients with some depressive symptomatology improved. Of these, 17 were clearly depressed. The remaining 29 correspond to the group with partial symptomatology (P<.001) (Fig. 2).

Fig. 2.

Evolution of depression. A reduction can be observed in the number of patients with depression (cases) at the annual check-up.

HAD: Hospital Anxiety and Depression questionnaire.

(0.07MB).

The levels of preoperative anxiety in this sample did not influence quality of life, although statistical significance was close (P=.055) (Table 3). Preoperative depression did not influence quality of life (P=.876).

Preoperative anxiety influenced pain levels measured on the VAS. The VAS scores, measure at one year following the intervention, showed a greater reduction in pain levels in the patients with preoperative anxiety than in those without anxiety (P=.02) (Table 4).

Anxiety in this study did not affect the functional outcomes of TKA measured with the KSS in the own knee subscale (P=.808) and function subscale (P=.860) (Table 4).

Preoperative depression did not influence differences in pain scores assessed by the VAS (P=.723), or the functional results of the own knee subscale (P=.448), or the functional subscale (P=.770).

Regarding degree of satisfaction, 84.2% (n=219) expressed an outcome classified as good or very good, while 15.8% (n=41) expressed a fair or poor result.

The presence of preoperative anxiety and depression is considered, at least by part of the medical literature, a predictor of poor outcomes following orthopaedic surgery. Complementarily, there are also studies that, after prosthetic replacement of a joint, observe an improvement in previous levels of anxiety and depression.

However, there also publications that report negatively on the relationship between psychological problems and surgical outcomes, as well as other studies that do not find mental improvement after surgery.

On analysing the references in an attempt to understand what is happening with such different outcomes, we found that a large number of different scales have been used. This might be why the outcomes are not interchangeable,17,18 and therefore apparently contradictory conclusions could be drawn.

Therefore we consider, in assessing the results of orthopaedic surgery, that the use of validated and specific questionnaires is necessary in any current clinical investigation.19

We used the HADS10 in our study to assess mental health, which allows us to detect anxiety disorders and depression with the advantage of not being contaminated by the symptoms of the patients’ physical disorder, in this specific case osteoarthritis of the knee.

The literature states that patients with chronic pain often feel depressed, anxious and have more physical complaints.20,21 When we focus on patients with osteoarthritis of the knee or hip, the publications22,23 also report a high prevalence of anxiety (43%) and depression (38%). The literature also describes percentages of anxiety and depression higher than those of our series (26.05%) and (13.40%), respectively, although in our case only patients with osteoarthritis of the knee and not the hip were included.

Equally notable are the high rates of anxiety (30.35%) and depression (50%) present postoperatively in TKA or total hip arthroplasty (THA) patients.23

There are studies9,24–27 that relate anxiety and/or depressive disorders with a lower degree of satisfaction after surgery, higher likelihood of developing complications of the surgical wound and/or higher costs in TKA implantation. Costs were not higher in patients with anxiety and depression when a TKA was implanted.

Unlike anxiety, preoperative depression appears to be related to poor results on functional knee scores,6,22 it being difficult to establish whether it is the severity of the osteoarthritis that is causing an increase in the level of depression or, by contrast, it is depression that is affecting the perception of symptoms, which would make patients feel the effects of their disease and end up scoring higher in the test.

Although the presence of pain and poor subjective function in patients who are to undergo TKA are considered predictors of preoperative anxiety and depression,28 the associations of these preoperative depressive symptoms with subsequent poor outcomes in pain and function is not clear in the literature.

In our series the patients with preoperative anxiety showed a significantly greater reduction in pain levels after TKA than those who did not.

By contrast, preoperative anxiety and depression did not influence the functional outcomes of TKA assessed using the KSS and, although close to statistical significance in the group of patients with anxiety, did not affect quality of life either (P=.055).

In the analysis of quality of life scores measured by WOMAC, it is surprising that the patients with preoperative anxiety did achieve significantly better results in the dimension of pain (P=.019), which indicates that studies with a greater number of cases could, hypothetically, reach statistical significance in this section on quality of life. These results could be explained by the fact that the perception of pain, both with the VAS scale and with the WOMAC pain dimension, was higher in the patients with anxiety.

In our study, TKA managed to improve the psychological status of the patients, statistically significantly reducing preoperative levels of anxiety (preoperative HADS-A 26.05% and 16.1% at one year) and depression (preoperative HADS-D 13.40% and 6.9% at one year). These results are similar to those obtained by Cho et al.7 in a study of shoulder arthroplasties, Pietrzak et al.8 following arthroplasty in patients with RA and Duivenvoorden et al.9 in a combined study on TKA and THA. In all these studies the number of patients with preoperative anxiety and depression reduced after the intervention. Unlike our results, the paper by Riddle et al.29 found no reduction in depressive symptoms after a procedure like TKA.29

The literature includes papers like that of Blackburn et al.30 who, confirming our results in the reduction of post-operative anxiety and depression, observed – unlike our series – an improvement in the functional outcomes of the knee at 3 and 6 months following the intervention. However, this was a sample of only 40 TKAs and used a different assessment questionnaire used, the Oxford Knee score.30

Our study, like that of the abovementioned authors,7–9,30 shows that joint pain in the knee, hip and shoulder would contribute to the onset of psychological symptoms. We could infer from our results that a successful TKA would offer an excellent opportunity to improve both the soma and the psyche It would confirm the hypothesis that patients with anxiety and depression in this study would achieve the same good outcomes following TKA as the rest of the patients in the sample, and that mental health would be improved through physical improvement.

We agree, therefore, that the difficulty in interpreting preoperative anxiety and depression and the outcome of TKA lies in establishing whether they are the cause or effect of knee pain, and that the different methods for assessing results are not necessarily interchangeable. The eminently mechanistic nature of our specialty could imply a limitation of the study, and undoubtedly, new trials that include the implementation of pre- and postoperative psychological therapies31 by mental health professionals could contribute to better control that would prevent possible biases during follow-up.

Preoperative anxiety and depression in this study did not influence the functional outcomes of TKA as measured by the KSS or the quality of life as assessed by the WOMAC questionnaire.

TKA reduced preoperative levels of anxiety and depression.

The differences between the preoperative and the annual scores of the different groups – case, non-case and doubtful case – classified by the HADS, both for anxiety and depression, were statistically significant (P<.001) (Figs. 1 and 2).

The patients with preoperative anxiety showed a greater, statistically significant reduction in pain levels assessed with the VAS scale after arthroplasty.

The authors have no conflict of interests to declare.