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Depression, somatisation and pain beliefs influence outcome of several painful musculoskeletal disorders. Their influence on the postoperative outcome of total hip replacement was investigated. A total of 79 patients who underwent primary total hip replacement completed questionnaires preoperatively and six weeks postoperatively addressing depression (Hospital Anxiety and Depression Scale–German version), pain beliefs (Pain Beliefs Questionnaire) and somatisation (Screening of Somatoform Disorders-2) as well as outcome [Western Ontario McMaster Universities Osteoarthritis Index (WOMAC), Medical Outcomes Study 36-Item Short Form (SF-36)]. Depressive patients showed a median preoperative WOMAC sum score of 30 compared to 45 in other patients and a postoperative score of 72 compared to 85, and patients with somatoform disorder of 32 compared to 46 preoperatively and 73 versus 86 postoperatively. Patients with high somatisation and depression scores feel worse in their hips and in general well-being before and after surgery, but they experienced the same benefit from total hip replacement as those with low scores.
La dépression due à la somatisation et les douleurs résiduelles peuvent influencer le devenir instantané des troubles musculo-squelettique douloureux des prothèses totales de hanches. 79 patients ont bénéficié d’une prothèse totale de hanche et ont rempli un questionnaire préopératoire et à six mois post-opératoire en ce qui concerne la dépression (HADS-D), les douleurs résiduelles (Pain Beliefs Questionnaire) et la somatisation (SOMS-2). Ils ont également rempli le questionnaire WOMAC et le SF-36. Les patients dépressifs montrent un score moyen WOMAC à 30 et ceci peut être comparé au score de 45 pour les autres patients en préopératoire. En postopératoire le score est à 72 comparé aux autres patients qui sont à 85. Les patients somatisant leurs problèmes ont un résultat à 32 comparés à 46 en préopératoire de même en postopératoire, 76 versus 86. Les patients qui présentent une somatisation importante avec une dépression ont une aggravation de leur score avant et après l’intervention mais ils auront le même bénéfice de la prothèse totale de hanche que ceux qui ont un score inférieur.
Total hip replacement (THR) normally leads to a considerable increase in quality of life resulting in a decrease of pain and in an increase of functional ability of the hip joint. But some patients are not satisfied with the outcome of hip arthroplasty although there are neither clinical nor radiological reasons for this. Janis  in general surgery and Kimball  in heart surgery were perhaps the first to point out the relation between psychological disorders and surgical results. Several authors [10, 13–17] have shown the influence of depression on recovery after treatment of hip fractures. Brander et al.  showed that preoperative depression and anxiety were associated with elevated pain at one year after total knee replacement. Pacault-Legendre et al. showed recently that of 64 patients after THR with pain without physical causes a psychiatric origin could be identified in all but one case . To our knowledge, this relationship has not yet been investigated in a longitudinal study of THR.
The aim of this study is to analyse whether psychological influences such as depression, somatisation and pain beliefs have an influence on the postoperative outcome of THR surgery.
The cohort study was approved by the local Ethics Committee (UN 1818 number 207/4.3). Before inclusion, the patients signed an informed consent.
Patients scheduled for elective THR were recruited consecutively. The conditions for inclusion were age over 18 years and the intellectual and linguistic ability to complete the questionnaires. Patients with revision surgery, infection of the hip joint, rheumatic diseases, fractures of the hip and cancer were excluded from the study. Of 139 patients 105 agreed to participate in the study (48 men, 57 women) with an average age of 68 years. The oldest was 81 and the youngest 28 years old. Two of these patients could not be operated upon due to their health status; two were excluded from the study because of rheumatoid arthritis and psoriatic arthritis, respectively, so that 101 completed the questionnaires at baseline investigation. Nineteen did not send back the questionnaires for follow-up examination. Therefore, at follow-up six to eight weeks after surgery 82 patients (78%) had returned the completed questionnaires. In 79 patients (75%) there was complete information on preoperative and postoperative data. Usually patients returned the questionnaires within two weeks. Only two came back half a year later.
The day before surgery at baseline examination the patients had to complete five self-reporting measures.
WOMAC and SF-36 were recently recommended as the most frequently used outcome measures after total hip and knee arthroplasty . Somatisation has been shown to be associated with poor outcome especially in treatment of low back pain .
Statistical analysis All data were analysed by means of SPSS (Statistical Package for the Social Sciences 11.0, SPSS Inc., Chicago, IL, USA), using a t-test, Levene’s test for differences of variation and Pearson’s correlation coefficient. The significance level was set at 0.05.
Within the follow-up time there were no dislocations of the hip joints. One patient suffered a deep wound infection and underwent exploration, spacer implantation and replacement. This patient completed the follow-up questionnaire when he was in traction after prosthesis explantation waiting for staged implantation in another hospital.
Table 1 shows the main results of the entire cohort of patients. The HADS values in the subscores depression and anxiety showed no significant difference between baseline and follow-up examination. Taking the cut-off scores for HADS depression subscale by Herrmann , seven patients suffered a borderline and nine patients a manifest depression before surgery as well as seven and five, respectively, at follow-up. PBQ scores did not significantly change after surgery.
The SF-36 questionnaire showed a clear postoperative amelioration of all subscales with the exception of role limitations due to emotional and mental health. In particular the subscales pain (+30 points) physical function (+18) and vitality (+10 points) improved considerably. The WOMAC score showed a significant improvement in the subscales and in the total score.
The pre- and postoperative HADS-D scores for depression and anxiety correlated with the SOMS-2 somatisation symptom count (p<0.01). Patients with somatisation or depression had lower scores on the SF-36 scales and a lower WOMAC score preoperatively as well as after surgery (Figs. 3 and and44).
The preoperative and postoperative differences in the WOMAC score between patients with somatoform disorder (Fig. 3) or depression (Fig. 4) in comparison to the rest of the cohort are shown. Depressive patients had a lower median WOMAC sum score of 30 (versus 46) preoperatively and 72 (versus 85) postoperatively. However, the difference of more than 10 median WOMAC points between depressive and non-depressive patients did not change so much from preoperative to postoperative assessment.
Some patients suffer from pain or show a relatively poor functional outcome after THR although the X-ray result may be excellent and no obvious adverse events have occurred. Even further examinations like bone scans, lab examinations and ultrasound do not reveal the cause of pain. This article suggests that depression and somatoform disorder may sometimes explain the relatively inferior outcome in some patients after THR.
Both depression and somatoform disorders can be diagnosed before surgery as well as after surgery and may cause an inferior health status, functional status or pain before as well as after operation. The tendency of somatisation is associated with depressive symptoms . This study also shows that there is a significant correlation between preoperatively measured somatisation and preoperatively and postoperatively measured depression.
The presence of a psychological disorder is not a contraindication to an operative intervention. There is rather an independent effect of organic and psychological disorders on health status and hip function. In order to achieve the best result in our patients, both disorders have to be treated.
To our knowledge, this study is the first one dealing systematically with depression, somatisation and pain beliefs before and after THR. Lingard and Riddle  used the WOMAC and Beck’s Depression Inventory in total knee replacement patients. They found that psychological distress predicts pain and function subscales at all time points of their study. As in their study we could demonstrate that the changes in the WOMAC scores from preoperative to postoperative for the psychologically distressed patients were not significantly different from those for the non-distressed patients.
The patient can complete the questionnaires for depression and somatisation in 15 min, and the analysis requires two minutes of the surgeon’s or of an assistant’s time. Preoperative screening and the consecutive treatment may improve patient-perceived outcome and may reduce costs. Herrmann et al.  with regard to stroke, Mossey et al.  with regard to hip fractures as well as Brandner et al.  with regard to knee replacement have recommended such a screening in order to optimise treatment, to improve patient-perceived outcome and to reduce the costs of treatment.
Our study has a longitudinal design, showing that preoperative depression and somatisation are associated with a worse outcome at six weeks. The follow-up time in this study does not allow us to draw the conclusion that the difference will continue to exist for a longer time after surgery. However, our results add evidence that somatic pain and functional status are worse in depressive patients and those with somatoform disorder whether severe organic pain is present (preoperative) or ameliorated (six weeks follow-up).
Patients with high somatisation and depression scores felt worse in their hips and in general well-being before and after surgery, but they experienced the same benefit from THR as those with low scores.
No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.