Economic burden of knee replacement, a case of Bushehr, Iran in 2023–2024

Abstract

Introduction

Joint disorders are diseases or injuries that affect the joints and disrupt their function. When non-surgical treatments do not effectively relieve joint pain and disability, arthroplasty (joint replacement surgery) is performed, with knee replacement surgery being the most common. This study aimed to calculate the economic burden of knee joint replacement surgery in patients referred to hospitals in Bushehr province in 2023–2024.

Method

This cross-sectional study is an economic evaluation that examines the cost of disease from a social perspective. This study was conducted in Bushehr, Iran and included all eligible patients in 2023–2024 as the study population (n = 257). A researcher-made data collection form was used to gather data. A prevalence-based approach and a bottom-up method were employed to calculate costs. Data on direct medical, direct non-medical, and indirect costs were obtained from patients’ files, insurance bills, and self-reports from patients or their companions. The human capital approach was used to calculate indirect costs.

Result

The results showed that in 2023–2024, the average total cost per person for knee joint replacement was $10,083.75, with the largest share attributed to direct medical costs, amounting to $8,892.89. The largest components of direct medical cost, direct non-medical cost, and indirect cost were related to joint prosthesis ($4,260), Transportation ($152), and absence from work due to illness ($622.64). Additionally, the average total cost for women was higher than for men ($10,207.56 vs. $10,020.13), and among age groups, the highest average total cost was in those aged 61–70 years, amounting to $10,297.87.

Conclusion

The findings of this study indicate that the largest contribution to direct medical costs comes from joint prostheses. Given the increasing age of the population and the high prevalence of skeletal diseases such as osteoarthritis, which necessitate knee joint replacement surgery, the costs associated with treatment and joint replacement surgery can impose a significant economic burden on society, the healthcare system, patients, and the country’s insurance structure. It is suggested that mechanisms for insurance coverage and government subsidies for joint prostheses be established.

Introduction

Text box 1. Contributions to the literature
• Musculoskeletal diseases are the leading cause of disability worldwide. Knee replacement surgery is one of the most common and cost-effective musculoskeletal procedures.
• The results showed that in the average total cost per person for knee joint replacement was $10,120.12. The findings of this study indicate that the largest contribution to direct medical costs comes from joint prostheses.
• Given that a significant portion of patients' direct medical costs are linked to joint prostheses, and considering that many patients often pay these costs out of pocket, it is advisable to develop an appropriate mechanism for insurance coverage and government subsidy allocation for joint prostheses

Musculoskeletal diseases are the leading cause of disability worldwide [1]. The musculoskeletal system comprises the skeleton, joints, cartilage, ligaments, muscles, and tendons [2]. Joints can be affected by injuries and disorders that disrupt their function. One such condition is osteoarthritis, a degenerative joint disease characterized by joint pain and dysfunction due to the progressive and irreversible loss of articular cartilage [3]. Osteoarthritis is the most prevalent joint disorder, exacerbated by an aging population and associated with increasing socio-economic impacts [4]. Joint damage may arise from excessive use or sudden injuries, such as those sustained in accidents or sports [5]. When non-surgical treatments fail to alleviate joint pain and disability, arthroplasty is performed [6]. Arthroplasty refers to joint replacement surgery, in which the damaged joint is removed and replaced with an artificial joint [7].

Knee replacement surgery is one of the most common and cost-effective musculoskeletal procedures. The number of knee replacement surgeries performed worldwide is on the rise, with significant variations in usage across different regions and countries. The primary indication for this surgery is painful arthritis of the knee, which results in reduced function and diminished quality of life [8].

The demand for knee replacement surgery is increasing. In the United States, a projected 673% rise in knee joint replacements is anticipated between 2005 and 2030 [9]. In the member countries of the Organization for Economic Cooperation and Development, the rate of knee joint replacements rose by 35% from 2009 to 2019 [10].

Following joint replacement surgery, hospitalization is typically required, with an average length of stay of 3 days [11]. Patients incur various costs for this surgery, a significant portion of which is attributed to the price of the prosthesis [12]. The medical field is unique, resulting in numerous direct and indirect costs that impact individuals, society, and the health system [13]. A 2022 study in England estimated the average one-year hospitalization expenses for knee joint replacement at £7,805 [14]. A 2020 study in Denmark reported annual costs for patients at approximately €16,343 [15]. Additionally, a 2012 study in Italy found the average cost per patient for knee joint replacement to be €15,358 [16].

Cost of illness studies, often referred to as disease burden analyses, evaluate the various impacts of disease on health outcomes at national, regional, community, and individual levels. Assessing the cost of illness is considered a necessary evaluation technique in healthcare [17]. Given the importance of this issue and the lack of comprehensive studies on this subject, this study aimed to calculate the economic burden of knee replacement surgery in Iran (patients referring to hospitals in Bushehr) in 2023–2024.

Method

This study is a descriptive, cross-sectional, and cost-of-illness studies assessing the economic burden of knee joint replacement surgery. It adopts a societal perspective for cost calculation, encompassing all direct medical costs, direct non-medical costs, and indirect costs, thereby providing a comprehensive analysis of all expenses related to the disease [18]. The research population included all individuals who underwent knee joint replacement surgery in the hospitals of Bushehr(Government and non-government public hospitals) province in 2023–2024. According to hospital records, 268 patients received knee replacement surgery during the study period. Data were collected using a census approach. Eleven patients were excluded due to undergoing simultaneous bilateral knee replacements or presenting with multiple traumatic injuries, resulting in a final sample size of 257 patients. These exclusion criteria were applied to avoid overestimation and misclassification of costs, as bilateral procedures and multiple traumas substantially alter resource utilization, length of hospital stay, rehabilitation needs, and productivity loss compared to standard unilateral knee replacement surgery, thereby limiting cost comparability across patients.

Costing approach

In this study, a bottom-up approach was utilized, offering more accurate and detailed information on the costs associated with the disease and resource utilization compared to a top-down approach [19]. This bottom-up approach relies on patient-level input data to estimate the number and type of services provided in each cost center [20]. It is also important to note that this study is prevalence-based. Prevalence-based studies estimate annual costs and assess the financial impact of a disease over a specific period, typically one year, regardless of the duration of the disease’s prevalence [20]. Costs were initially collected at the individual patient level and recorded in Iranian Rials (IRR). They were then converted to United States dollars (USD) using the official exchange rate for Iran in 2023 (42,000 IRR per USD) [23]. In addition, to ensure purchasing power parity and facilitate international comparability, costs were converted to international dollars (Int$) using the World Bank indicator “PPP conversion factor, GDP (LCU per international dollar),” which for Iran in 2023 was equal to 9,435,798 IRR per international dollar.

Data collection tool

Data were collected using a researcher-developed cost data collection checklist, designed based on the study objectives, an extensive review of cost-of-illness literature, and existing validated instruments used in similar studies. The initial draft of the checklist was developed after reviewing published studies on orthopedic cost analyses and knee replacement surgery. The checklist was subsequently refined through expert consultation with two orthopedic surgeons and three faculty members specializing in health economics and healthcare management to ensure content relevance and completeness.

The content validity of the tool was assessed qualitatively through expert review, focusing on clarity, relevance, comprehensiveness, and consistency with standard cost classifications. Minor revisions were made based on expert feedback. A pilot test was conducted on a small sample of patients (n = 15) to assess feasibility, clarity, and completion time. Based on pilot findings, ambiguous items were revised, and the final version of the checklist was approved for data collection. The final data collection tool consisted of four sections:

1. Demographic and clinical data of the patient (age, sex, marital status, education, employment status, insurance coverage, place of residence, disease characteristics, body mass index, length of stay, type of diagnosis, etc.).

2. Data related to the direct medical costs, subdivided into inpatient costs (Visit and consultation, Nursing Services, Surgery, medicine, consumables, radiology, Taping, laboratory, Hotelling, Package of nursing services and care, Physiotherapy, Ultrasound, CT scan, Joint prosthesis) extracted from hospital medical records, and outpatient costs (Visit, Medicine, Radiology, Taping, laboratory, Physiotherapy, CT scan, MRI) obtained through financial invoices and patient or caregiver interviews.

• The cost of the joint prosthesis was determined based on the source of provision; specifically, when supplied by the hospital, the cost was obtained from the hospital bill, and when supplied by the patient, it was obtained from the patient’s official purchase invoice.

• To minimize recall bias, the recall period was limited to the most recent episode of care, and respondents were encouraged to refer to receipts, discharge documents, or personal records when available. Additionally, the structured format of the questionnaire and the use of standardized prompts helped improve consistency and accuracy of responses.

• 3.Information regarding direct non-medical costs, including transportation, accommodation, food expenses, purchase of assistive devices, home modifications related to the patient’s condition, and paid nursing care, collected through structured interviews with patients or their companions.
• 4.Data on indirect costs related to productivity loss of patients and caregivers, collected via interviews using self-reported data on work absence and reduced productivity.

Indirect cost estimation

The human capital approach was employed to calculate indirect costs in this study. This method measures the loss of productivity due to illness by using individuals’ wages [21].

Absenteeism was defined as the number of days during which individuals were completely unable to perform their usual productive activities due to surgery, hospitalization, or recovery.

For non-wage earners, including housewives and students, absenteeism was calculated as the number of days they were unable to perform their usual household or educational activities, and these lost days were valued using the daily minimum wage established by the Ministry of Labor in 2023–2024 as a proxy income measure. The officially approved minimum monthly wage for that year was US$1,740 [22].

Productivity losses beyond absenteeism, such as reduced work efficiency(presenteeism) or long-term productivity losses, were not considered.

Statistical analysis

Descriptive statistics, including frequency, mean, and percentage, were used to summarize demographic characteristics and cost components. Prior to inferential analysis, data normality was assessed. To compare cost differences in the relevant subgroups, an independent t-test was used for cost differences in the two groups of women and men, and a one-way analysis of variance (ANOVA) test was used for cost differences in age groups. All analyses were conducted using Microsoft Excel 2019 and SPSS version 26.

In this study, each US dollar was valued at 42,000 Rials, based on the exchange rate published by the Central Bank of the Islamic Republic of Iran in 2023–2024 [23].

Results

Demographic and clinical finding

The study analyzed 257 patients who underwent knee replacement surgery at hospitals in Bushehr province in 2023–2024. The majority of the patients were female (72.38%), aged 61–70 years (49.41%), married (94.16%), had an undergraduate education (40.46%), were housewife and student(61.47%), resided in Bushehr cities (44.74%), had social security insurance (45.13%) and reported no income (73.54%) (Table 1).

Table 1.

Demographic and clinical characteristics of knee replacement patients referred to Bushehr hospitals in 2023–2024

Specifications	Items	Frequency (%) (N = 257)
Gender	Male	71
	Female	186(72.38%)
Age	19–50	11(
	51–60	74(28.79%)
	61–70	127(49.41%)
	71–91	45(17.5%)
Marital status	singe	14(%)
	married	242(94.16%)
	other	1(0.38%)
Education level	illiterate	55
	Under diploma	104(40.46%)
	diploma	61(23.73%)
	university	37(14.39%)
Employment status	Unemployed	32(12.45%)
	Employee	10(3.89%)
	Self-employed	23(8.94%)
	retired	34(13.22%)
	Housewife and student*	158(61.47%)
Place of residence	Bushehr	108(41.02%)
	Bushehr cities	115(44.74%)
	outside the province	34(13.22%)
Patient income	No income	189(73.54%)
	1500–3400$	27(10.5%)
	3500–4400$	35(13.61%)
	4500–5500$	6(2.33%)
Types of basic health insurance coverage	Iran health insurance	87(33.85%)
	social security	116(45.13%)
	Armed forces	38(14.78%)
	other	10(3.89%)
	No insurance	6(2.33%)
Length of stay	2–4 days	254(98.83%)
	5–7 days	3(1.16%)
diagnosis	Arthritis	171(66.53%)
	Joint disorder	50(19.45%)
	other	36(14%)
BMI	< 18.5	4(1.55%)
	18.5–24.5	77(29.96%)
	25-29.9	105(40.85%)
	30-34.9	34(13.22%)
	35-39.9	23(8.94%)
	> 40	14(5.44%)
Smoking	smoking	146(56.8%)
	Non-smoking	111(43.19%)

* Including 157 housewives and one student

Additionally, in clinical indicators, most patients had a length of stay of 2–4 days (98.83%), With the diagnosis of arthritis(66.53%), had a body mass index between 25 and 29 (40.85%), and were smokers (56.8%) (Table 1).

Results related to cost

The average total cost knee replacement surgery per patient was $10,083.75 (Table 2). The largest portion of this cost came from direct medical costs, totaling $8,892.89 (88.19%), while direct non-medical costs accounted for the smallest share at $422.31 (4.09%) (Table 3).

Table 2.

Mean cost components of knee replacement surgery by cost category in Bushehr Province, Iran, 2023–2024 (N = 257)

Cost Category	Cost item	Mean ± SD (USD)	95% CI (USD)	Mean ± SD (Int$ PPP)	95% CI (Int$ PPP)	% of Total
Direct medical costs	Visit and consultation 1	229.75 ± 91.10	218.61 – 240.89	1.02 ± 0.41	0.97 – 1.07	2.28%
	Nursing services 2	151.08 ± 124.53	135.85 – 166.31	0.67 ± 0.55	0.60 – 0.74	1.50%
	Surgery	2,000.00 ± 532.08	1,934.95 – 2,065.05	8.90 ± 2.37	8.61 – 9.19	19.84%
	Medicines (total) 3	403.60 ± 106.68	390.56 – 416.64	1.80 ± 0.47	1.74 – 1.86	4.00%
	Consumables (total) 4	474.68 ± 655.30	394.56 – 554.80	2.11 ± 2.92	1.75 – 2.47	4.71%
	Imaging 5	232.51 ± 64.23	224.66 – 240.36	1.03 ± 0.29	0.99 – 1.07	2.31%
	Laboratory tests 6	190.83 ± 46.59	185.13 – 196.53	0.85 ± 0.21	0.82 – 0.88	1.89%
	Physiotherapy 7	179.94 ± 285.09	145.08 – 214.80	0.80 ± 1.27	0.64 – 0.96	1.78%
	Taping 8	59.80 ± 117.30	45.46 – 74.14	0.27 ± 0.52	0.21 – 0.33	0.59%
	Hotelling	614.70 ± 245.00	584.75 – 644.65	2.74 ± 1.09	2.61 – 2.87	6.09%
	Joint prosthesis	4,260.00 ± 1,102.40	4,125.22 – 4,394.78	18.96 ± 4.91	18.36 – 19.56	42.25%
	Other services	96.00 ± 107.19	82.89 – 109.11	0.43 ± 0.48	0.37 – 0.49	0.95%
	Subtotal – Direct medical	8,892.89 ± 1,013.60	8,768.97 – 9,016.81	39.59 ± 4.51	39.04 – 40.14	88.19%
Direct non-medical costs	Transportation	152.00 ± 83.16	141.83 – 162.17	0.68 ± 0.37	0.63 – 0.73	1.51%
	Food	90.00 ± 85.59	79.54 – 100.46	0.40 ± 0.38	0.35 – 0.45	0.89%
	Accommodation	138.00 ± 210.10	112.31 – 163.69	0.61 ± 0.94	0.50 – 0.73	1.37%
	Home modifications	9.26 ± 47.63	3.44 – 15.08	0.04 ± 0.21	0.02 – 0.07	0.09%
	Assistive devices	9.68 ± 39.77	4.82 – 14.54	0.04 ± 0.18	0.02 – 0.06	0.10%
	Nursing and care	23.62 ± 122.18	8.68 – 38.56	0.11 ± 0.54	0.04 – 0.18	0.23%
	Subtotal – Direct non-medical	422.31 ± 325.17	382.55 – 462.07	1.88 ± 1.45	1.70 – 2.06	4.19%
Indirect costs	Patient absenteeism	622.64 ± 366.00	577.89 – 667.39	2.77 ± 1.63	2.57 – 2.97	6.17%
	Companions’ absenteeism	145.92 ± 171.00	125.01 – 166.83	0.65 ± 0.76	0.56 – 0.74	1.45%
	Subtotal – Indirect	768.56 ± 403.97	719.17 – 817.95	3.42 ± 1.80	3.20 – 3.64	7.62%
Total costs		10,083.75 ± 1,153.13	9,942.77 – 10,224.73	44.89 ± 5.13	44.26 – 45.52	100.00%

¹Visits and consultations include inpatient visits (USD 7.50) and outpatient visits (USD 222.25)

²Medical nursing services and care include inpatient nursing services (USD 10.08) and packaged nursing services (USD 141.00)

³Medicines include inpatient ward medicines (USD 164.74), operating room medicines (USD 92.36), and outpatient medicines (USD 146.50)

⁴Consumables include ward consumables (USD 53.42) and operating room consumables (USD 421.26)

⁵Imaging services include radiology (USD 44.79 inpatient and USD 64.73 outpatient), ultrasound (USD 0.44), computed tomography (CT) scans (USD 0.38 inpatient and USD 4.17 outpatient), and magnetic resonance imaging (MRI) (USD 118.00)

⁶Laboratory tests include inpatient (USD 46.59) and outpatient (USD 144.24) laboratory services

⁷Physiotherapy services include inpatient (USD 6.68) and outpatient (USD 173.26) sessions

⁸Taping services include inpatient (USD 1.59) and outpatient (USD 58.21) procedures

Table 3.

Mean direct medical, direct non-medical, and indirect costs of knee replacement surgery in Bushehr Province, Iran, 2023–2024

Type of costs	Mean ± SD (USD)	95% CI (USD)	Mean ± SD (Int$ PPP)	95% CI (Int$ PPP)	% of Total
Direct medical costs	8,892.89 ± 1,013.60	8,768.97 – 9,016.81	39.59 ± 4.51	39.04 – 40.14	88.19%
Direct non-medical costs	422.31 ± 325.17	382.55 – 462.07	1.88 ± 1.45	1.70 – 2.06	4.19%
Indirect costs	768.56 ± 403.97	719.17 – 817.95	3.42 ± 1.80	3.20 – 3.64	7.62%
Total costs	10,083.75 ± 1,153.13	9,942.77 – 10,224.73	44.89 ± 5.13	44.26 – 45.52	100.00%

Furthermore, the joint prosthesis constituted the largest share of the average direct medical costs, at $4,260(42.25%). The largest average direct non-medical cost was for transportation of the patient and companions, at $152 (1.51%). Lastly, the highest average indirect cost, attributed to The patient’s absenteeism due to illness, was $622.64 (6.17%) (Table 2).

The average total cost for knee replacement surgery was significantly higher for women compared to men ($10,207.56 vs. $10,020.13) (p-value = 0.014) (Table 4). The age group of 61–70 years incurred the highest average total cost, although this difference was not statistically significant ($10,297.87) (p-value = 0.184) (Table 4).

Table 4.

Comparison of mean total costs of knee replacement surgery across age groups and gender in Bushehr Province, Iran, 2023–2024

Variable	Category	Mean ± SD (USD)	95% CI (USD)	Mean ± SD (Int$ PPP 2023)	95% CI (Int$ PPP 2023)	P-value
Gender	Male (n=71)	10,020.13 ± 1,229.98	9,734.03 – 10,306.23	44.59 ± 5.47	43.32 – 45.86	0.014*
	Female (n=186)	10,207.56 ± 1,224.32	10,031.61 – 10,383.51	45.42 ± 5.45	44.64 – 46.21
Age group (years)	<51 (n=11)	10,122.57 ± 1,056.00	9,498.51 – 10,746.63	45.05 ± 4.70	42.27 – 47.82	0.184**
	51–60 (n=74)	9,968.79 ± 1,228.55	9,688.87 – 10,248.71	44.36 ± 5.47	43.12 – 45.61
	61–70 (n=127)	10,297.87 ± 1,224.32	10,084.93 – 10,510.81	45.83 ± 5.45	44.88 – 46.77
	71–91 (n=45)	10,070.38 ± 1,231.54	9,710.55 – 10,430.21	44.81 ± 5.48	43.21 – 46.41

*Independent t-tests

**one-way analysis of variance (ANOVA)

Cost benchmarking against national economic indicators

The mean total cost of total knee replacement per patient was US$10,083.75. When benchmarked against national economic indicators, this cost was equivalent to approximately 200% of Iran’s GDP per capita in 2023 (US$5,049.3) and 579% of the annual minimum wage (US$1,740).

Discussion

The present study was conducted to estimate the cost of total knee replacement surgery from a societal perspective, simultaneously examining direct medical, direct non-medical, and indirect costs. Adopting this perspective allows for a comprehensive assessment of the economic burden imposed on patients, households, and society within the context of Iran’s health system—an aspect that is often overlooked in economic evaluations limited to the payer or health system perspective and, as a result, inadequately reflects distributional consequences and issues of financial equity.

From a demographic standpoint, the majority of patients undergoing total knee replacement were women aged 61–70 years, most of whom were married, had an educational level below a high school diploma, and lacked independent income. This pattern is consistent with the existing literature and aligns with the findings of Ackerman et al. (2019) and Morgan et al. (2023) [24, 25]. The higher prevalence of knee replacement among older women likely reflects the greater burden of advanced knee osteoarthritis in this group, a phenomenon attributable to a combination of age-related degenerative changes, postmenopausal bone density loss, hormonal alterations, pregnancy history, and cumulative mechanical stress on the knee joint. The concentration of this high-cost intervention among low-income or income-less groups further underscores the importance of financial protection and equity considerations in Iran’s health system.

In terms of economic burden, the findings indicate that direct medical costs constituted the dominant component of the social cost of total knee replacement, accounting for more than 88% of total costs. This pattern is consistent with prior studies, including Loza et al. (2009), Carducci et al. (2020), and Waimann et al. (2014) [26–28], and highlights the cost of joint prostheses and surgical procedures as the principal cost drivers of this intervention. In contrast, Leardini et al. (2004) reported a higher share of indirect costs [29]. Such discrepancies can be explained by structural differences in health systems and labor markets, whereby countries with higher wage levels and more extensive social protection systems experience a greater contribution of productivity losses and work absenteeism to total costs.

In the Iranian context, the predominance of direct medical costs reflects key structural features of health financing. Heavy reliance on imported joint prostheses, vulnerability to exchange rate fluctuations, the absence of efficient centralized procurement mechanisms, and limited bargaining power of the health system have collectively contributed to substantial increases in the prices of these capital-intensive inputs. Consequently, a large share of these costs is transferred to patients through out-of-pocket payments. In contrast, health systems based on universal coverage—such as those in Denmark and the United Kingdom—benefit from national-level centralized procurement, long-term contracts with manufacturers, and comprehensive insurance coverage, enabling effective cost containment for high-priced technologies and significantly reducing patients’ financial exposure.

In this study, direct non-medical costs, accounting for 4.17% of total costs, represented the smallest component of the social cost. Within this category, transportation costs for patients and accompanying persons constituted the largest share, likely reflecting the concentration of specialized knee replacement services in a limited number of provincial centers and the need for repeated visits for postoperative follow-up and rehabilitation. This pattern differs from the findings of Leardini et al. (2004) [29], who reported a higher contribution of home care costs. One plausible explanation is the lack of monetary valuation of informal care provided by family members in the present study, which may have led to an underestimation of this cost component.

Indirect costs accounted for 7.62% of total costs, primarily resulting from patients’ work absenteeism during hospitalization and the recovery period. This finding is consistent with Leardini et al. (2004) [29] and indicates that productivity loss remains a relevant component of the economic burden of total knee replacement, particularly for households reliant on daily income or lacking adequate employment and insurance protection.

Subgroup analyses showed that the mean direct medical, direct non-medical, and indirect costs were higher among women and individuals aged 61–70 years. This pattern, consistent with the findings of Feng et al. (2007) and Leardini et al. (2004) [29, 30], likely reflects greater disease severity, higher utilization of health services, and longer recovery periods in these groups.

Studies in the field of burden of disease have demonstrated that reliance on nominal exchange rates in international comparisons can lead to an underestimation of costs, whereas converting costs into international dollars using purchasing power parity (PPP) allows for a more accurate reflection of real differences in cost levels across countries [31].

Accordingly, in the present study, estimating the cost of total knee replacement using PPP conversion factors for 2023 resulted in a substantial increase in relative costs in international comparisons, placing Iran within the range reported for upper-middle-income countries. Nevertheless, even after PPP adjustment, the cost structure remains fundamentally different from that observed in countries with universal health coverage. In countries with established universal health coverage, economic evidence indicates that the majority of direct medical costs are financed by public payers or pooled financing mechanisms, thereby limiting out-of-pocket payments and protecting patients against catastrophic health expenditures [32].

Overall, the findings indicate that total knee replacement in Iran is associated with a high per-capita cost (USD 10,083.75) and a pronounced dominance of direct medical costs (88.19% of total costs), a cost structure more closely resembling that of cardiovascular diseases than cancers in the Iranian context. In the study by Gholamhoseini et al. (2024) among elderly patients with cardiovascular diseases, direct medical costs constituted the primary component of the economic burden, with a substantial share attributable to hospitalization, diagnostic-therapeutic procedures, and medications—an expenditure pattern consistent with the present findings [33]. Conversely, the systematic review by Irandoust et al. (2025) on the economic burden of five common cancers in Iran indicates that although direct medical costs in many cancers are comparable to or even higher than those of knee replacement, indirect costs—particularly those arising from premature mortality, disability, and productivity loss—play a far more prominent role and, in some cancers, constitute the dominant component of the total economic burden [34].

Beyond its aggregate magnitude, the economic burden of total knee replacement carries important distributional implications. The findings indicate that the average cost of surgery amounts to approximately 5.8 times the annual minimum wage, reflecting a substantial and regressive financial burden on low-income households. This level of out-of-pocket expenditure significantly exceeds internationally recognized thresholds for catastrophic health spending and signals a heightened risk of health-related impoverishment, particularly among older adults and households lacking stable income or comprehensive insurance coverage. These results highlight critical gaps in financial risk protection and underscore the need for effective risk-pooling arrangements within Iran’s health financing system to prevent further socioeconomic vulnerability.

This structural difference suggests that total knee replacement primarily imposes a severe, concentrated, and short-term financial shock at the individual and household level, whereas cancers and cardiovascular diseases, owing to their high prevalence, chronic or fatal trajectories, and broader impact on labor productivity, generate a cumulative, long-term, and multidimensional economic burden at the national level. The dominance of direct medical costs and the high share of out-of-pocket payments render total knee replacement one of the most potentially impoverishing surgical interventions for older adults and low-income households in Iran, underscoring the urgent need for targeted financial protection and cost-containment policies for technology-intensive care.

From a policy perspective, the findings suggest that supportive interventions should not be limited to subsidizing joint prostheses alone. The development of transparent and centralized procurement mechanisms, strengthening domestic production with robust quality standards, rational decentralization of knee replacement services to reduce patients’ transportation costs, and the implementation of anti-corruption policies to curb informal payments could collectively play a critical role in mitigating the financial burden of this intervention and enhancing financial equity within Iran’s health system.

Limitations

This study did not capture informal payments, which may occur in the context of elective surgical procedures such as total knee replacement. Informal payments—including unrecorded payments to clinicians or hospital staff—are difficult to measure and are not routinely documented in hospital billing systems. As a result, the reported costs likely underestimate the true out-of-pocket financial burden borne by patients.

Future research that includes household-level surveys or qualitative methods and includes informal payments could provide a more comprehensive assessment of the costs associated with knee replacement surgery.

Conclusion

Based on the findings, the average total cost per patient for total knee replacement was US$10,120.12, with the largest share of direct medical costs attributable to the joint prosthesis (US$8,929.26). Given that a substantial proportion of these costs is borne out of pocket by patients, and potentially compounded by informal payments, strengthening insurance coverage and government subsidy mechanisms for joint prostheses may help mitigate the financial burden associated with this procedure.

Author contributions

AJ, RR, and MD contributed to the idea and design. HE contributed tothe data collection. All authors contributed to the data analysis. All authorscontributed to the manuscript writing and revision. All authors approved thefinal version of the manuscript.

Funding

The present article was extracted from the thesis written by Hamid Ebrahimi and was financially supported by Shiraz University of Medical Sciences grant No. 29992.

Data availability

No datasets were generated or analysed during the current study.

Declarations

Ethical approval

This study was approved by the Shiraz University of Medical Sciences Ethics Committee (Code: IR.SUMS.NUMIMG.REC.1403.013). To participate in this study, all the patients or their companions were taken written informed consent, and all were assured of the confidentiality of their responses.

Competing interests

The authors declare no competing interests.