Targeting Pain Catastrophizing before Total Knee Arthroplasty: Effects of Home-Based Multimodal Physiotherapy—A Randomized Trial

Introduction

Chronic postsurgical pain is discomfort that begins or worsens after surgery or tissue damage and persists well beyond the normal healing period [1]. After total knee arthroplasty (TKA), this issue affects approximately 20% of patients [2]. Pain catastrophizing and high preoperative pain intensity rank among the strongest predictors of unfavorable results, such as increased disability [3, 4], poorer quality of life [5], and long-term chronic pain [4, 6-9].

Pain catastrophizing is generally understood as the tendency to dramatically amplify the threat of pain, experience helplessness, and fail to control pain-related thoughts in anticipation of, during, or after painful events [10]. However, Petrini and Arendt-Nielsen [11] recently offered a fresh biopsychosocial perspective, framing it as an emotional regulation tactic involving catastrophic worry—repetitive negative thinking—that emerges from rumination and certain personality traits associated with the behavioral inhibition system.

Experts increasingly recommend identifying patients with high catastrophizing before surgery and applying specific interventions to lower both catastrophizing and pain levels, which may optimize joint replacement success [12-14]. Only a handful of studies have examined this approach. Birch et al. [15] and Buvanendran et al. [16] investigated cognitive behavioral therapy, while Riddle et al. [17] focused on pain-coping skills training in similar high-risk TKA populations. These trials generally found no major differences between groups, with only one reporting a clear preoperative reduction in catastrophizing [16].

Although cognitive behavioral therapy currently has the most robust support [18], multimodal physical therapy has also proven capable of lowering pain intensity and catastrophizing in osteoarthritis patients awaiting TKA who display strong pain catastrophizing [19].

Thus, the main objective of this study was to compare two preoperative home-based multimodal physical therapy programs—both featuring pain neuroscience education, therapeutic exercise, and coping skills training—in their ability to reduce preoperative pain catastrophizing in high-catastrophizing patients scheduled for TKA. Secondary goals involved assessing effects on pain catastrophizing, general health functioning, fear of movement due to pain, self-efficacy, walking speed, and dynamic balance both preoperatively and postoperatively.

Materials and Methods

Design  

This investigation was designed as a single-blinded, three-arm parallel-group randomized controlled trial. It took place at Hospital Germans Trias I Pujol between September 2019 and January 2023. The trial was prospectively registered in the United States Clinical Trials Registry (NCT03847324). Ethical clearance was obtained from the Human Research Ethics Committee of Hospital Germans Trias i Pujol (PI-18-239) and the Research Ethics Committee of the University of Vic–Central University of Catalonia (58/2018). The study followed the reporting guidelines of the Consolidated Standards of Reporting Trials (CONSORT) Statement for Randomized Trials of Nonpharmacologic Treatments [20].

Participants 

Eligibility criteria and recruitment details were fully described in an earlier feasibility study [19]. Individuals qualified for inclusion if they (i) were awaiting primary TKA for symptomatic osteoarthritis; (ii) had shown no adequate response to non-surgical treatments; (iii) presented moderate to severe knee pain (≥ 40 mm on a 100 mm visual analog scale) [21]; (iv) obtained a minimum score of 20 on the Pain Catastrophizing Scale (PCS) [22]; (v) volunteered to join the research; and (vi) possessed sufficient Spanish language comprehension and reading ability. Patients were not enrolled if they (i) required revision surgery or unicompartmental knee replacement, or (ii) had inflammatory arthritis. Three orthopedic surgeons (EGA, FAO, and JHH) screened and confirmed participant suitability after TKA scheduling.

Sample size calculation 

The required number of participants was estimated using findings from the preceding feasibility study [19]. Calculations were performed with G*Power 3 (version 3.1, Düsseldorf, Germany), using the PCS score as the primary outcome variable [23]. The effect size (η2 = 0.37) was based on post-treatment PCS differences between the intervention and control groups, corresponding to a Cohen’s f of 0.78. With a desired power of 0.90, α = 0.05, and a 25% anticipated dropout rate, the analysis indicated that 33 participants (11 per group) would be needed.

Randomization and blinding 

Random assignment to the control or intervention arms was achieved using a computer-generated sequence generated by a web-based random number generator (GraphPad QuickCalcs, Boston, MA, USA). Allocation was concealed using sequentially numbered, opaque sealed envelopes [24]. Only the physiotherapist conducting the outcome evaluations was kept unaware of group assignments.

Interventions 

Complete details of the interventions are available in the prior feasibility study [19]. Control group participants received only routine care, which included a single multidisciplinary biomedical education session before surgery and standard inpatient physiotherapy starting on the day of surgery. This inpatient phase emphasized early mobilization and walking, typically continuing until hospital discharge, approximately 4 days after the procedure. Post-discharge, patients were referred to an external home-based rehabilitation service that usually commenced within one to ten days, followed by ongoing domiciliary physiotherapy.

The therapeutic patient education (TPE) group received standard care plus three individual home-based preoperative sessions centered on pain neuroscience education (PNE) and coping skills training (CST). PNE focused on explaining the neurobiological aspects of pain to reshape patients’ understanding, beliefs, and coping approaches. CST incorporated instruction in therapeutic exercises, self-mobilization methods, and relaxation strategies. The combined approach sought to improve pain management, physical function, and diminish negative cognitive patterns, including pain catastrophizing.

The multimodal physiotherapy (MPT) group received standard care plus eight individual home-based preoperative sessions. This more intensive program combined therapeutic education (PNE + CST), supervised exercise training, and manual therapy techniques. Exercise supervision was substantially higher, with progressive monitoring and adjustment across 8 weeks. The strengthening, balance, and stability program addressed core, hip, knee, and whole-body areas through specific movements: core work included selective abdominal activation, kneeling planks, and side planks; hip/pelvic exercises featured supine and single-leg pelvic bridges, side-lying abductions, and standing abductions with resistance bands; knee exercises consisted of isometric quadriceps sets, banded knee extensions, weighted straight-leg raises, supported half-squats, and forward lunges; global activities included single-leg balance, weighted step-ups, slow step-downs, sit-to-stand transitions, and diaphragmatic breathing. Manual therapy included tailored joint mobilizations for limited knee motion, patellar glides, soft-tissue dynamic techniques, nerve mobilizations, and knee traction, as needed, for pain relief and mobility restoration.

The preoperative phase started 2–3 months before surgery during the waiting-list period. Participants were encouraged to practice the prescribed coping strategies and exercises regularly. Treatment adherence was measured at the final preoperative assessment. All participants received identical standard postoperative care.

Outcome measures 

All evaluations were conducted by a blinded physiotherapist at the initial assessment, immediately after completing the preoperative program (8 weeks from baseline), and at 1, 3, and 6 months following surgery. Before the trial, the assessor completed targeted training to ensure strict adherence to the testing protocols. Although the majority of data were collected through self-reported questionnaires, each question was carefully reviewed with participants, and clear, standardized explanations were provided when needed. To ensure consistency and reduce potential bias, the same experienced physiotherapist conducted every assessment. Ongoing quality monitoring and protocol audits were also implemented during the study. 

The main outcome of interest was pain catastrophizing, assessed using the validated Spanish version of the Pain Catastrophizing Scale (PCS). This is a 13-item self-report tool that includes three subscales: rumination, magnification, and helplessness [22]. 

Secondary outcomes consisted of: 

• Pain intensity, recorded on a 100 mm visual analog scale (VAS) [0 = no pain, 100 = worst imaginable pain], both at rest and while walking [25]. 
• Overall health functioning, measured with the Western Ontario and McMaster University Index (WOMAC), a 24-item questionnaire divided into pain, stiffness, and physical function domains, scored on a 5-point Likert scale [0 = none, 4 = extreme] [26]. 
• Pain-related fear of movement, assessed via the Tampa Scale of Kinesiophobia-11 (TSK-11), an 11-item scale with total scores ranging from 11 to 44 (higher scores indicate stronger fear) [27]. 
• Self-efficacy, determined by the Chronic Pain Self-Efficacy Scale (CPSES), a 19-item questionnaire using a 10-point Likert scale [0 = totally incapable, 10 = totally capable] [28]. 
• Walking speed, tested using the 4 m Walking Test (4mWT), where participants walked at their fastest comfortable pace along an 8 m walkway (including 2 m for acceleration and 2 m for deceleration) [29]. 
• Dynamic balance, evaluated with the Y-Balance Test (YBT). Participants balanced on one leg on a central platform and reached maximally in the anterior, posteromedial, and posterolateral directions with the free leg [30]. The YBT was not performed at the 1-month postoperative visit due to safety considerations.

Statistical analysis 

Statistical analysis was performed using the Statistical Package for the Social Sciences (SPSS 28; SPSS Inc., Chicago, IL, USA). Baseline information was presented as means ± standard deviations for continuous variables and as counts with percentages for categorical variables. Data distribution was examined with the Shapiro–Wilk test. As the variables did not meet normality assumptions, all analyses relied on nonparametric tests. Group differences at baseline were assessed using the Kruskal–Wallis test for continuous data and the chi-squared or linear chi-squared test for categorical data. When Kruskal–Wallis results were significant, Dunn’s post-hoc tests with Bonferroni correction were applied for pairwise comparisons. Changes within each group over time were analyzed using Friedman’s ANOVA, with follow-up Wilcoxon signed-rank tests for specific intervals. Between-group effect sizes were estimated from the Kruskal–Wallis H statistic using the formula εR2H(n2-1)/(n+1) , where n is the total sample size [31]. These values were classified as very small (< 0.01), small (0.01– < 0.06), medium (0.06– < 0.14), and large (≥ 0.14) [32]. Within-group effect sizes were calculated as r = Z/√n based on the Wilcoxon Z value [31] and interpreted as small (> 0.1), medium (> 0.3), or large (> 0.5) [32].

Results and Discussion

Between 19 September 2019 and 18 March 2022, 126 patients were screened. Only 40 of them satisfied all eligibility requirements and were randomly allocated to the control group (n = 15), TPE group (n = 13), or MPT group (n = 12). Altogether, 86 patients were excluded. In the control group, two individuals dropped out due to the COVID-19 lockdown, and one was removed after failing to undergo the scheduled operation. Three participants from the TPE group were lost due to the COVID-19 lockdown. Similarly, two participants in the MPT group were lost for the same reason. A complete overview of exclusions and retention is displayed in Figure 1.

The baseline sociodemographic and clinical features of the sample are summarized in Table 1. No statistically significant differences existed between the three groups at the start of the study. 

Kruskal–Wallis Test; †Pearson’s Chi-squared Test; ‡Linear Chi-squared Test. Abbreviations: TPE = Therapeutic Patient Education Group; MPT = Multimodal Physiotherapy Group.

Between-group comparisons (Table 2)

No statistically significant differences were found among the three groups for any outcome at baseline (T0). However, right after the preoperative program ended (T1), clear differences emerged across several key variables: PCS, VAS Walk, WOMAC total score, TSK-11, CPSES, YBT-A, YBT-M, and YBT-L. 

Compared with the control group, the TPE group achieved significantly better results in PCS, VAS Walk, TSK-11, and YBT-A. The MPT group performed notably better than the control group in PCS, WOMAC total score, TSK-11, CPSES, YBT-A, YBT-M, and YBT-L. 

At one month after surgery (T2), meaningful group differences remained in PCS, VAS Rest, VAS Walk, TSK-11, and CPSES. The TPE group again showed advantages over the control group in PCS, VAS Rest, and CPSES, while the MPT group outperformed the control group in PCS, VAS Walk, TSK-11, and CPSES. 

By the three-month postoperative point (T3), significant differences were observed only in TSK-11, CPSES, YBT-A, and YBT-M. The TPE group surpassed the control group on TSK-11 and YBT-A, and the MPT group performed better than the control group on TSK-11, CPSES, and YBT-A. 

At the final six-month follow-up (T4), significant inter-group differences appeared in PCS, VAS Rest, TSK-11, CPSES, 4 m Walking Test, YBT-A, YBT-M, and YBT-L. The TPE group achieved higher scores than the control group on PCS, VAS Rest, TSK-11, and YBT-M. The MPT group demonstrated better performance than the control group in TSK-11, CPSES, the 4 m Walking Test, and YBT-L. 

Effect size calculations indicated large effects at T1 for PCS, VAS Rest, VAS Walk, WOMAC total score, TSK-11, CPSES, YBT-A, YBT-M, and YBT-L. Large effects were also present at T2 for PCS, VAS Rest, VAS Walk, WOMAC total score, TSK-11, and CPSES. At T3, large effects were seen for TSK-11, CPSES, YBT-A, and YBT-M. At T4, large effects were recorded for PCS, VAS Rest, WOMAC total score, TSK-11, CPSES, 4 m Walking Test, YBT-A, YBT-M, and YBT-L. 

Control vs. TPE; † Control vs. MPT; ‡ TPE vs. MPT. Abbreviations: Con = Control Group; TPE = Therapeutic Patient Education Group; MPT = Multimodal Physiotherapy Group; IQR = Interquartile Range; PCS = Pain Catastrophizing Scale; VAS = Visual Analog Scale; WOMAC = Western Ontario and McMaster Universities Osteoarthritis Index; TSK-11 = Tampa Scale of Kinesiophobia; CPSES = Chronic Pain Self-Efficacy Scale; YBT = Y-Balance Test (A, Anterior; M, Medial; L, Lateral).

Intragroup comparison of different operative periods (Table 3) 

Nearly every outcome measure showed a clear, statistically significant improvement from baseline (T0) to the six-month follow-up after surgery (T4). The only exception was CPSES, which did not improve significantly in the control group. 

In the preoperative phase, designed to capture the short-term impact of preparatory interventions, the control group showed a statistically significant gain solely in YBT-A, with no meaningful shifts in any other parameter. By comparison, the TPE group achieved marked and clinically relevant improvements, characterized by large effect sizes, across a broad set of outcomes: PCS, VAS Rest, VAS Walk, WOMAC Pain, WOMAC total score, TSK-11, CPSES, YBT-A, and YBT-M. Similarly, the MPT group demonstrated substantial gains with large effect sizes in PCS, VAS Rest, VAS Walk, WOMAC Pain, WOMAC total score, TSK-11, CPSES, YBT-A, YBT-M, and YBT-L. 

During the perioperative window (from T1 to T2), the control group showed notable progress with large effect sizes in PCS, WOMAC Pain, and WOMAC total score. The TPE participants experienced significant advances, also with large effect sizes, in VAS Rest, VAS Walk, WOMAC Pain, and WOMAC total score. The MPT group, for its part, recorded significant improvements in VAS Walk, WOMAC Pain, and the WOMAC total score. 

The postoperative phase was analyzed in two separate intervals. In the first interval (T2 to T3), the control group showed significant improvements, with large effect sizes, in PCS, VAS Rest, WOMAC Pain, WOMAC total score, and the 4 m Walking Test. The TPE group followed a comparable pattern, improving significantly in VAS Rest, WOMAC Pain, WOMAC total score, and the 4 m Walking Test. The MPT group likewise showed meaningful gains in PCS, VAS Rest, WOMAC Pain, WOMAC total score, CPSES, and the 4 m Walking Test. 

In the second postoperative interval (T3 to T4), the control group showed no further significant improvement. In contrast, the TPE group continued to register significant benefits in WOMAC Pain and WOMAC total score, while the MPT group achieved additional significant improvements in VAS Rest and YBT-L.

Baseline vs. Post-treatment; † Post-treatment vs. 1 month post-surgery; ‡ 1 month post-surgery vs. 3 months post-surgery; § 3 months post-surgery vs. 6 months post-surgery. Abbreviations: Con = Control Group; TPE = Therapeutic Patient Education Group; MPT = Multimodal Physiotherapy Group; IQR = Interquartile Range; PCS = Pain Catastrophizing Scale; VAS = Visual Analog Scale; WOMAC = Western Ontario and McMaster Universities Osteoarthritis Index; TSK-11 = Tampa Scale of Kinesiophobia; CPSES = Chronic Pain Self-Efficacy Scale; YBT = Y-Balance Test (A = Anterior; M = Medial; L = Lateral).