Exploring persistent postsurgical pain from the patient’s perspective 5 years after total knee arthroplasty

A mixed-methods study

Abstract

Background: Osteoarthritis (OA) of the knee is a common ailment and is estimated to affect 240 million people globally, with 10% of men and 18% of women over 60 years having symptomatic knee OA. The main symptom of OA is pain, stiffness, and reduced function of the joint. Total knee arthroplasty (TKA) remains the treatment of choice in moderate to severe knee OA, when non-surgical treatments are no longer effective in alleviating symptoms. Unfortunately, approximately 20% of patients operated with primary TKA experience pain 12 months after surgery, with 15-19% reporting severe pain. With an anticipated increase in TKA procedures over the next decade, the number of patients living with persistent postsurgical pain (PPP) one year after surgery becomes substantial. Little is known about these patients’ outcomes and lives with PPP 5 or more years after TKA. Hence, this PhD project includes the patient’s perspective, exploring PPP over the first 5-7 years post-TKA.

Aim: The overall aim of this PhD thesis was to explore experiences of PPP in patients 5-7 years after TKA.

Methods: This thesis had a hybrid mixed-methods (MM) design, employing features from two independent parallel strands (one quantitative and one qualitative), as well as one explanatory sequential strand. The data was obtained from questionnaires and qualitative interviews with patients who underwent primary TKA for OA in a high-volume surgical clinic in Oslo. The MM design allowed for different perspectives and voices to explore the complex phenomenon of PPP within three sub-studies, and the findings were combined and presented in a joint display.

Study 1: Quantitative strand (n=136). A prospective longitudinal observational study design was employed to examine the associations between preoperative factors and moderate-tosevere pain and pain-related functional impairment 5 years after TKA. Socio Now Pop was employed to assess patients’ sociodemographic characteristics at baseline. Patient-reported outcome measures assessed at 5 years included the Brief Pain Inventory (BPI) and the Hospital Anxiety and Depression Scale. To assess associations between selected preoperative factors and moderate-to-severe pain or pain-related functional impairment at 5 years, statistically significant factors from univariate regressions were entered into a multiple logistic regression model.

Study 2: Qualitative strand (n=23). An explorative-descriptive qualitative design was employed to explore earlier experiences of pain and stress in patients with PPP at 12-months. Semi-structured interviews were conducted at 5-7 years, transcribed verbatim and analyzed through qualitative content analysis.

Study 3: Mixed-methods strand (qualitative=23, quantitative n=19). A sequential, explanatory design was employed to explore patients’ experiences of living with persistent pain 5-7 years after primary TKA. The BPI questionnaire was filled out at three timepoints. Semi-structured interviews were conducted at one timepoint. The quantitative analysis included descriptive and non-parametric statistics to compare the demographics of included and excluded patients. In addition, two multivariate mixed models for repeated measures were employed to estimate within‐patient and between‐patient differences, as well as to assess the effect of time on pain with walking, daily activity, and average pain. Interviews were analyzed through qualitative content analysis. The findings were integrated and presented in a joint display.

Results: Study 1 showed that severe preoperative pain, more preoperative painful sites, and more preoperative anxiety are associated with moderate-to-severe pain 5 years after surgery. More preoperative anxiety was also associated with pain-related functional impairment. Male sex was associated with less pain-related functional impairment; more severe OA was associated with less pain 5 years after TKA surgery. Study 2 identified two main themes: 1) Painful years – the burden of living with long lasting pain and 2) The burden of living with psychological distress. The participants told stories of severe long lasting knee pain and pain in other locations preoperatively. Moreover, the women had additional painful conditions that the men did not have. Participants’ stories included stressful experiences such as anxiety, grief, and loss, which impacted their lives over time. Study 3 identified three main themes: 1) persistent limitations after TKA, 2) regaining wellness over time, and 3) complexity in physical challenges. Limitations included PPP with certain movements and after physical activities. Other painful conditions and ailments may have hampered the knee rehabilitation process. Noteworthy, those with PPP at 12 months, experienced an overall decrease in pain 5-7 years after surgery, and no-one regretted their TKA at the time of the interview, 5-7 years after surgery.

Conclusion: The study provides insight into non-improving TKA patients as individuals and suggests ways of identifying patients who are at risk for developing PPP after TKA. These are patients who may benefit from personalized care and perioperative pain management. Health personnel who interact with patients preoperatively may use the findings from the current study to inform and guide patients on strategies for coping with pain, comorbidity, and function in the time leading up to surgery. Furthermore, health personnel may support and guide those with delayed improvements in pain toward more realistic expectations for recovery and rehabilitation.