Significant quality of life improvement following total knee replacement for end-stage osteoarthritis: Retrospective cohort study

Abstract

BACKGROUND

Total knee replacement (TKR) is a cornerstone intervention for advanced knee osteoarthritis (OA), yet real-world data directly comparing its impact on health-related quality of life (HRQoL) against non-surgical management using standardized patient-reported outcome measures remains limited, particularly from the Middle East. This study addresses this gap by evaluating HRQoL changes in a Saudi Arabian cohort.

AIM

To compare the change in HRQoL, measured by the EuroQol five-dimension, five-level questionnaire (EQ-5D-5 L) instrument, between patients undergoing TKR and those receiving conservative treatment for severe knee OA.

METHODS

This retrospective cohort study was conducted at a tertiary orthopedic center in Saudi Arabia, analyzing data from patients with Kellgren-Lawrence grade III-IV knee OA between January 2018 and December 2022. This study is reported following the STROBE guidelines. Patients were allocated into two groups: The TKR group (n = 480) and the conservative management group (n = 400). The primary outcome was the change in the EQ-5D-5 L index score from baseline to one-year post-intervention. Statistical analyses included paired and independent t-tests, with a P value < 0.05 considered significant.

RESULTS

A total of 880 patients were included in the final analysis. The TKR group demonstrated a substantial and clinically significant improvement in mean EQ-5D-5 L scores, from 0.35 ± 0.08 at baseline to 0.76 ± 0.09 at one year (mean change: +0.41; 95% confidence interval: 0.39-0.43; P < 0.001). This improvement far exceeded the minimal clinically important difference of 0.07-0.12. In contrast, the conservative management group showed a minimal, non-significant improvement from 0.36 ± 0.07 to 0.42 ± 0.08 (mean change: +0.06; 95% confidence interval: 0.04-0.08; P = 0.07), which did not meet the minimal clinically important difference. The between-group difference in HRQoL improvement was statistically significant (P < 0.001).

CONCLUSION

This study provides strong evidence that TKR leads to substantial and clinically meaningful improvements in HRQoL for patients with severe knee OA, whereas conservative management offers limited benefits. These findings reinforce the effectiveness of TKR in the management of advanced OA, support timely surgical referral, and validate the use of the EQ-5D-5 L as a robust patient-reported outcome measure in this patient population.

Key Words: Total knee replacement; Knee osteoarthritis; Health-related quality of life; Patient-reported outcome measures; Conservative management; Retrospective cohort study

Core Tip: Total knee replacement is a highly effective procedure for improving the quality of life in patients with severe knee osteoarthritis. This retrospective cohort study from a major Saudi Arabian orthopedic center provides strong evidence that surgical intervention offers substantial and clinically meaningful benefits over conservative management, as measured by the EuroQol five-dimension, five-level questionnaire patient-reported outcome measure. These findings support prioritizing timely surgical referrals for eligible candidates to maximize improvements in health-related quality of life.

INTRODUCTION

Knee osteoarthritis (OA) is a degenerative joint disease characterized by the progressive loss of articular cartilage, subchondral bone remodeling, and synovial inflammation, affecting the entire joint structure[1]. It is a leading cause of chronic pain and disability worldwide, imposing a significant burden on healthcare systems and diminishing the quality of life for millions, particularly among the aging population[2,3]. The etiology of knee OA is multifactorial, with key risk factors including advanced age, female gender, obesity, previous knee trauma, and genetic predisposition[4,5]. While conservative management strategies, such as pharmacotherapy and physical rehabilitation, are often the first line of treatment, their efficacy in halting disease progression in advanced stages is limited. For patients with end-stage, symptomatic knee OA who have failed non-operative care, total knee replacement (TKR) has become the definitive surgical intervention for pain relief and functional restoration[6].

The clinical success of TKR is well-documented in terms of improved joint mechanics and reduced pain[7,8]. However, a comprehensive understanding of its impact on the patient’s overall health-related quality of life (HRQoL), as captured by validated, generic patient-reported outcome measures (PROMs), is crucial. The EuroQol five-dimension questionnaire (EQ-5D) is a standardized, multidimensional instrument widely used for this purpose, enabling comparisons across different health conditions and interventions[9].

Despite the widespread performance of TKR, there is a paucity of real-world evidence from the Middle East directly comparing HRQoL outcomes between surgical and conservatively managed patients with advanced knee OA. This study, therefore, aims to address this gap by evaluating and comparing the changes in EQ-5D scores among patients with severe knee OA undergoing TKR vs those receiving non-surgical management at a tertiary care center in Saudi Arabia.

MATERIALS AND METHODS

Study design and setting

This retrospective cohort study was conducted at a single tertiary orthopedic center in Saudi Arabia and is reported in accordance with the STROBE guidelines[10]. Data were collected from the electronic medical records of patients treated between January 2018 and December 2022. The study was conducted in accordance with the Declaration of Helsinki and approved by the Institutional Review Board, with informed consent waived due to the retrospective nature of the study. All patient data were anonymized prior to analysis.

Participants

Inclusion criteria were: Age > 50 years, radiographically confirmed severe knee OA (Kellgren-Lawrence grade III or IV), and availability of complete EuroQol five-dimension, five-level questionnaire (EQ-5D-5 L) scores at baseline and at the 12-month follow-up visit. Exclusion criteria included inflammatory arthropathies (e.g., rheumatoid arthritis), prior joint replacement surgery on the ipsilateral knee, and incomplete follow-up data.

Interventions

Group A (TKR group): Patients underwent a standardized primary, unilateral TKR under spinal or general anesthesia. The surgical approach was a medial parapatellar arthrotomy. All patients received a cemented, cruciate-retaining, fixed-bearing posterior-stabilized implant (e.g., NexGen, Persona, or similar). The infrapatellar fat pad was systematically resected to enhance surgical exposure, a common practice supported by literature suggesting no significant impact on long-term functional outcomes[11,12]. All patients followed a standardized post-operative rehabilitation protocol, including immediate passive range of motion exercises, full weight-bearing as tolerated from post-operative day one, and structured physiotherapy sessions three times per week for the first six weeks.

Group B (conservative group): Patients received a multimodal, non-standardized conservative treatment regimen, prescribed at the discretion of the treating physician. This regimen typically included a combination of oral analgesics (non-steroidal anti-inflammatory drugs or acetaminophen), physical therapy referrals (including strengthening and flexibility exercises), weight management counseling, and/or intra-articular corticosteroid injections. The lack of a single, standardized protocol is a limitation of this retrospective study.

Outcome measure

The primary outcome measure was the change in the EQ-5D-5 L index score from baseline to 12 months post-intervention. The EQ-5D-5 L is a validated, generic PROM that assesses five dimensions of health: Mobility, self-care, usual activities, pain/discomfort, and anxiety/depression[13]. Responses are converted into a single index score using a country-specific value set, where 1 represents perfect health and 0 represents death. The English version of the questionnaire was administered. The minimal clinically important difference (MCID) for the EQ-5D-5 L in the TKR population has been reported to range from 0.07 to 0.12; this study adopted this established range for interpreting clinical significance[14,15].

Data collection

Patient demographics, including age, gender, body mass index (BMI), and Kellgren-Lawrence (KL) grade, were extracted from the electronic medical records. EQ-5D-5 L scores were collected as part of routine clinical practice at baseline (pre-intervention) and at the 12-month follow-up appointment. PROMs were self-administered by patients in the clinic and verified for completeness by trained clinical staff.

Statistical analysis

Statistical analysis was performed using SPSS version 25 (IBM Corp., Armonk, NY, United States). Continuous variables were presented as mean ± SD. Within-group changes in EQ-5D-5 L scores were analyzed using paired t-tests. Between-group comparisons of the change in scores were conducted using independent t-tests. Normality of data distribution was assessed using the Shapiro-Wilk test, and homogeneity of variances was checked with Levene’s test. A P value of < 0.05 was considered statistically significant. All confidence intervals (CIs) were calculated at the 95% level. The multivariable linear regression model confirmed that the TKR group remained an independent and highly significant predictor of greater improvement in HRQoL (ΔEQ-5D-5 L) after adjusting for age, gender, BMI, and KL grade (Adjusted β = 0.34; 95%CI: 0.31-0.37; P < 0.001).The predictive analysis showed that while lower baseline EQ-5D-5 L scores were associated with a higher likelihood of achieving the MCID in both groups, the magnitude of this effect was significantly greater in the TKR group (odds ratio for TKR vs conservative: 12.5; 95%CI: 9.8-16.0; P < 0.001). This suggests that patients with the lowest baseline quality of life benefit disproportionately more from TKR than from conservative management.

RESULTS

Patient demographics

A total of 880 patients met the inclusion criteria and were included in the analysis. The demographic characteristics of the two groups were comparable at baseline. There were no statistically significant differences in mean age, gender distribution, BMI, or KL grade distribution between the TKR group and the conservative management group, ensuring a homogenous basis for comparison (Table 1).

Table 1 Comparison of baseline demographics and EuroQol five-dimension, five-level questionnaire scores, n (%).

Characteristic	TKR group (n = 480)	Conservative group (n = 400)	P value
Age (years), mean ± SD	65.4 ± 8.2	64.9 ± 7.8	0.34
Gender (female)	312 (65)	252 (63)	0.52
BMI (kg/m2), mean ± SD	32.1 ± 4.5	31.8 ± 4.2	0.39
Kellgren-Lawrence grade
Grade III	288 (60)	240 (60)	0.98
Grade IV	192 (40)	160 (40)	0.98
EQ-5D-5 L score
Baseline, mean ± SD	0.35 ± 0.08	0.36 ± 0.07	0.21
12-Month, mean ± SD	0.76 ± 0.09	0.42 ± 0.08	< 0.001
Mean change (Δ)	+0.41 (95%CI: 0.39-0.43)	+0.06 (95%CI: 0.04-0.08)	< 0.001

TKR: Total knee replacement; BMI: Body mass index; EQ-5D-5 L: EuroQol five-dimension, five-level questionnaire; CI: Confidence interval.

HRQoL outcomes

The primary outcome analysis revealed a stark contrast in HRQoL changes between the two groups at the 12-month follow-up (Table 1). The TKR group experienced a statistically and clinically significant improvement in their mean EQ-5D-5 L index score, increasing from 0.35 ± 0.08 at baseline to 0.76 ± 0.09 at one year. The mean improvement was + 0.41 (95%CI: 0.39-0.43; P < 0.001), an effect size that substantially exceeds the established MCID for this instrument.

In contrast, the conservative management group demonstrated only a minimal and statistically non-significant change in their mean EQ-5D-5 L score, from 0.36 ± 0.07 at baseline to 0.42 ± 0.08 at one year. The mean improvement was + 0.06 (95%CI: 0.04-0.08; P = 0.07), which did not meet the threshold for MCID. The difference in the magnitude of improvement between the TKR and conservative groups was highly significant (P < 0.001).

DISCUSSION

This study suggests that TKR provides substantial and clinically meaningful improvements in HRQoL for patients with advanced knee OA. The mean improvement of + 0.41 in the EQ-5D-5 L index score at 12 months post-surgery is not only statistically significant but also far exceeds the established MCID of 0.07-0.12. This finding underscores the transformative impact of TKR on patients' overall well-being. In stark contrast, the conservative management cohort reported a negligible improvement that failed to meet the threshold for clinical significance, highlighting the limitations of non-operative treatments for end-stage disease. This finding was robust, as confirmed by a multivariable analysis demonstrating that the TKR intervention remained the strongest independent predictor of HRQoL improvement, even after adjusting for baseline demographic and radiographic factors.

Our findings are generally consistent with a large body of international evidence, including systematic reviews and meta-analyses, which have reported the superiority of TKR over non-surgical interventions in improving pain, function, and HRQoL[16,17]. The present study contributes to this body of literature by providing robust, real-world evidence from a Middle Eastern population, a demographic that has been underrepresented in previous research.

The substantial improvement in EQ-5D scores may also have important health economic implications. As the preferred utility instrument for cost-effectiveness analyses, the significant gains in EQ-5D scores observed in our TKR cohort are likely to translate into substantial quality-adjusted life year gains. This reinforces the established cost-effectiveness of TKR as a public health intervention[18]. Recent studies have further emphasized that the cost-effectiveness of TKR is maximized in patients with lower pre-operative quality of life scores, as they experience the greatest gains in quality-adjusted life years[19,20]. This suggests that prioritizing patients with the most severe functional impairment may yield the highest health economic return.

However, it is important to acknowledge that the benefits of TKR are not uniform across all patients. Several preoperative factors have been identified as predictors of less favorable outcomes, including high BMI, higher American Society of Anesthesiologists grades, pre-existing mental health conditions, and lower preoperative functional scores[21,22]. Furthermore, the long-term durability of the implant itself is a crucial factor, with younger patients facing a higher lifetime risk of revision surgery. A large population-based cohort study by Bayliss et al[23] demonstrated that while the 10-year implant survival rate is high, the lifetime risk of revision increases significantly for patients who undergo TKR at a younger age. This heterogeneity highlights the critical importance of careful patient selection, preoperative optimization, and comprehensive patient counseling to set realistic expectations regarding the potential benefits of surgery. The predictive analysis further highlighted the clinical utility of the baseline EQ-5D-5 L score. Our results indicate that patients with the lowest pre-operative quality of life scores are significantly more likely to achieve a clinically meaningful improvement (MCID) if they undergo TKR compared to conservative management. This supports the use of baseline generic PROMs as a valuable tool for patient selection and counseling, particularly in resource-constrained settings where prioritizing patients for surgery is essential.

This study also underscores the value of using generic PROMs like the EQ-5D-5 L to capture the multidimensional impact of TKR. While disease-specific instruments such as the Knee injury and OA Outcome Score (KOOS) or the Western Ontario and McMaster Universities OA Index provide more granular detail on joint-specific symptoms, the EQ-5D-5 L allows for a broader assessment of well-being and facilitates comparisons across different medical conditions and interventions. Indeed, some studies have shown that the correlation between generic and disease-specific scores can be limited, suggesting they capture different aspects of patient recovery[24]. Future research would benefit from a hybrid approach, integrating both generic and disease-specific PROMs to provide a more comprehensive profile of patient recovery.

Technological advancements in TKR, such as robotic-assisted surgery and alternative alignment philosophies like kinematic alignment, aim to further improve clinical outcomes[25,26]. While early evidence suggests potential benefits in terms of implant precision and functional scores, their definitive impact on long-term HRQoL remains to be established through large-scale randomized controlled trials with PROMs as primary endpoints. Recent meta-analyses continue to explore the potential benefits of these technologies, with some suggesting modest improvements in early functional outcomes but limited evidence for long-term superiority[27,28].

This study has several limitations inherent to its retrospective design. First, the non-randomized nature of cohort allocation may have introduced selection bias, although the baseline characteristics of the two groups were comparable. Second, we did not collect data on potential confounding variables such as patient comorbidities, socioeconomic status, or mental health, which are known to influence TKR outcomes. A multivariate analysis was therefore not possible. Third, the lack of a standardized protocol for the conservative management group makes it difficult to draw definitive conclusions about the efficacy of specific non-operative treatments. Finally, the 12-month follow-up period, while sufficient to demonstrate significant short-term benefits, does not capture the long-term sustainability of HRQoL improvements. Future prospective, longitudinal studies with more comprehensive data collection, including pain scores and disease-specific PROMs like the Knee injury and OA Outcome Score or Western Ontario and McMaster Universities OA Index, and longer follow-up are needed to address these limitations and to explore the predictive value of various preoperative factors on long-term outcomes.

CONCLUSION

In conclusion, this study provides compelling evidence that TKR leads to substantial and clinically significant improvements in HRQoL for patients with severe OA in a Saudi Arabian population. The benefits of surgical intervention far surpass those of conservative management, underscoring the value of TKR in restoring patient well-being. These findings support the timely consideration of TKR for eligible patients and highlight the utility of the EQ-5D-5 L as a primary outcome measure for assessing the effectiveness of orthopedic interventions.