Preoperative malnutrition is a risk factor for delayed recovery of mobilization after total hip arthroplasty

Effects of Malnutrition on Perioperative Outcomes of Total Hip Arthroplasty: A Systematic Review and Meta-Analysis

Background

Malnutrition can play a significant role in wound healing, immune response, and conditioning. The purpose of this review is to characterize definitions of malnutrition in total hip arthroplasty (THA) and analyze its effects on postoperative outcomes.

Methods

A systematic search was conducted using iterations of the key terms "total hip arthroplasty" and "malnutrition." Human studies describing malnutrition in patients undergoing primary THA for either traumatic or elective indications were included. Using the SPSS meta-analysis binary and continuous model function, the mean effect size estimate (MSE) or Cohen's d (Cd) statistic with 95% confidence interval was reported.

Results

This search yielded a total of 555 studies, of which 9 articles comprising 495,657 patients undergoing primary THA were included, characterizing 16,895 patients (3.4%) as malnourished. Studies characterized malnutrition as albumin <3.5 g/dL (n = 7) and total lymphocyte count <1500 (n = 1). Malnutrition was associated with an increased rate of nonhome discharge (MSE = 0.81, [0.55-1.07]) and likelihood of readmission (MSE = 0.86, [0.75-0.97]). Malnutrition at the time of surgery was also associated with increased rates of any complication (MSE = 1.01, [0.46-1.57]), wound complications (MSE = 1.04, [0.72-1.36]), pulmonary complications (MSE = 1.54, [1.29-1.78]), need for transfusion (MSE = 0.75, [0.54-0.96]), periprosthetic fracture (MSE = 0.65, [0.47-0.82]), reoperation (MSE = 0.72, [0.58-0.86]), and perioperative mortality (MSE = 2.05, [1.76-2.33]).

Conclusions

Malnutrition was found to have significant associations with complications and disposition following THA. The findings from this meta-analysis provide support for further investigation into perioperative nutritional supplementation strategies for surgeons to optimize at-risk patients prior to THA.

Level of Evidence

III.

Increasingly severe malnutrition according to the geriatric nutritional risk index is associated with a greater risk of postoperative adverse events

BACKGROUND

This study investigates the association between the geriatric nutritional risk index (GNRI), a readily available index measuring the risk of malnutrition, and 30-day postoperative complications following revision total knee arthroplasty (rTKA).

METHODS

The American College of Surgeons National Surgical Quality Improvement Program database was queried for all patients ≥ 65 who underwent rTKA between 2015 and 2021. The study population was divided into three groups based on preoperative GNRI: normal/reference (GNRI > 98), moderate malnutrition (92 ≤ GNRI ≤ 98), and severe malnutrition (GNRI < 92). Multivariate logistic regression analysis was conducted to investigate the association between preoperative GNRI and postoperative complications.

RESULTS

Compared to normal nutrition, moderate malnutrition was independently significantly associated with a greater likelihood of experiencing any complication, blood transfusions, surgical site infection (SSI), non-home discharge, readmission, length of stay (LOS) > 2 days, and mortality. Severe malnutrition was independently significantly associated with a greater likelihood of experiencing any complication, septic shock, pneumonia, unplanned reintubation, cardiac arrest or myocardial infarction, stroke, blood transfusions, still on ventilator > 48 h, SSI, wound dehiscence, acute renal failure, non-home discharge, readmission, unplanned reoperation, LOS > 2 days, and mortality. Severe malnutrition was independently significantly associated with a greater number of complications and had a stronger association with complications compared to moderate malnutrition.

CONCLUSION

Malnutrition identified by GNRI has strong predictive value for short-term postoperative complications following rTKA in geriatric patients and may have utility as an adjunctive risk stratification tool for geriatric patients undergoing rTKA.

Importance of hospital food intake for early discharge after total hip arthroplasty for osteoarthritis: a propensity score matching analysis

BACKGROUND

Total hip arthroplasty (THA) is widely used to treat hip osteoarthritis (HOA), particularly in elderly patients. However, the associated costs and complications highlight the need for strategies to shorten hospital stays and optimise postoperative outcomes. This study aimed to investigate the effect of preoperative nutritional status and postoperative dietary intake on the discharge outcomes of patients with unilateral HOA who underwent THA.

METHODS

A retrospective analysis of 57 patients without significant comorbidities out of 172 THA procedures performed by the same surgeon was conducted. Propensity score matching was used to compare the early discharge group (n = 14), discharged within 2 weeks, with the delayed discharge group (n = 14), hospitalised for longer. The assessed factors included preoperative Controlling Nutritional Status (CONUT) scores, postoperative dietary intake (staple foods and side dishes), and complications.

RESULTS

Preoperative malnutrition, as assessed using the CONUT score, showed no significant difference between the groups. The early discharge group exhibited a higher intake of staple foods (rich in carbohydrates) in the early postoperative phase than the delayed discharge group, potentially influencing earlier discharge. No significant difference was observed in side dish intake between the two groups. The incidence of complications did not differ between the two groups.

CONCLUSION

Higher intake of staple foods in the early postoperative period may positively impact metabolic demands and wound healing, suggesting the importance of dietary strategies in postoperative rehabilitation. Ensuring adequate hospital meal consumption and implementing effective dietary guidance and education are crucial for optimising recovery and reducing hospital stay. This study highlights that postoperative feeding strategies, especially staple food intake, may have a positive impact on early discharge in THA patients. Future studies should explore the benefits of long-term nutritional interventions and the role of continuous dietary education in enhancing postoperative recovery.

Association of Admission Nutritional Status Evaluated by Prognostic Nutritional Index with One-Year Walking Independence after Primary Total Hip Arthroplasty for Osteonecrosis of the Femoral Head: A Retrospective Matched Cohort Study Based on 1,152 Patients

BACKGROUND

Malnutrition is significantly associated with unfavorable outcomes, but the relevant prognostic assessment is not emphasized in patients who have osteonecrosis of the femoral head (ONFH). This study aimed to assess the association between preoperative nutritional status evaluated by the prognostic nutritional index (PNI) and walking independence at one year postoperatively in patients who have ONFH undergoing primary total hip arthroplasty (THA).

METHODS

This was a retrospective analysis of prospectively collected data from patients admitted to a tertiary referral hospital who had ONFH and underwent primary unilateral THA from October 30, 2014 to April 26, 2019. The restricted cubic spline was used to assess the dose-effect relationship between PNI and recovery of walking independence. Propensity score matching was performed to balance potential preoperative confounders, and multivariable conditional logistic regression analysis was applied to assess the association between malnutrition and losing walking independence (LWI) with perioperative and follow-up factors for further adjustment. Inverse probability treatment weighting and sensitivity analyses were performed to test the robustness of the results. Subgroup analyses were used to determine potential population heterogeneity.

RESULTS

We found a negative relationship between admission PNI levels and recovery of walking independence at one year postoperatively, and that low PNI (< 42.2) was independently associated with a 2.35-fold (95% CI [confidence interval], 1.16 to 4.77; P = 0.018) increased risk of LWI. The results were overall robust. Significant heterogeneities were observed in the subgroups of age, labor intensity, American Society of Anesthesiologists class, Charlson's comorbidity index, and Association Research Circulation Osseous stage (P for interaction < 0.05).

CONCLUSIONS

Preoperative low-level PNI is a significant risk factor for LWI after THA in patients who have ONFH. This finding supports nutritional screening and interventions for surgeons in decision-making for elective surgery and postoperative rehabilitation management.

Protein as a preoperative predictor - Impact of hypoalbuminemia on 30-day outcomes of breast reduction surgery

BACKGROUND

Hypoalbuminemia, a biomarker of malnutrition, has been associated with adverse surgical outcomes;, however, its impact on breast reduction surgery is not yet well-documented.

METHODS

We queried the American college of surgeons national surgical quality improvement program database to identify patients who underwent breast reduction surgery between 2008 and 2022. Patients were grouped by preoperative normal albumin levels (≥3.5 g/dL) and hypoalbuminemia (<3.5 g/dL). Preoperative, intraoperative, and 30-day postoperative outcomes, including complications and readmissions, were compared using the univariate tests and multivariable logistic regression.

RESULTS

We included a total of 7277 cases, among whom 96% (n = 6964) had normal albumin values and 4% (n = 298) had hypoalbuminemia (n = 298). Patients with hypoalbuminemia showed a significantly higher body mass index (37.1 ± 8.1 vs. 33.3 ± 6.3 kg/m², p < 0.001) and were more likely to be Black or African American (49.0 vs. 27.8%, p < 0.001). Comorbidities such as diabetes (14.7 vs. 7.4%, p < 0.001), chronic obstructive pulmonary disease (4.0 vs. 1.0%, p < 0.001), and hypertension (35.2 vs. 26.3%, p = 0.002) were significantly more prevalent in the hypoalbuminemia group. Hypoalbuminemia was associated with a significantly increased risk of complications (13.8 vs. 6.1%, p < 0.001), with higher rates of superficial incisional infections (7.0 vs. 2.6%, p = 0.001) and unplanned readmissions (3.4 vs. 1.4%, p = 0.05). Multivariable analysis confirmed hypoalbuminemia as an independent predictor of postoperative complications (OR 1.96, p = 0.001), medical complications (OR 2.62, p = 0.02), and surgical complications (OR 1.91, p = 0.02).

CONCLUSION

Hypoalbuminemia significantly raises the risk of 30-day postoperative complications in breast reduction surgery. Preoperative nutritional assessment and optimization are crucial in improving surgical outcomes, particularly in patients with high body mass index and comorbidities.

Loss of walking independence one year after primary total hip arthroplasty for osteonecrosis of the femoral head: incidence and risk prediction model

BACKGROUND

Assessment of postoperative ambulation in osteonecrosis of the femoral head (ONFH) patients treated with total hip arthroplasty (THA) is limited. This study aimed to define the incidence and risk factors for losing walking independence (LWI) at one-year postoperatively in patients with ONFH undergoing primary THA, and to establish and validate a predictive nomogram.

METHODS

This was a retrospective analysis of prospective collected data from patients admitted to a tertiary referral hospital with ONFH who underwent primary unilateral THA from October 2014 to March 2018. The Functional Independence Measure-Locomotion scale was used to quantify walking independence and was documented at a one-year continuous postoperative follow-up, which classified patients with a final score below 6 as LWI. Multivariate logistic regression identified independent risk factors for LWI, and a predictive nomogram was constructed based on the analysis results. The stability of the model was assessed using patients from April 2018 to April 2019 as an external validation set.

RESULTS

1152 patients were enrolled in the study, of which 810 were used in the training cohort and the other 342 for the validation cohort. The incidence of LWI was 5.93%. Multivariate analysis revealed that age 62 years or older (odd ratio (OR) = 2.37, 95% confidence interval (CI) 1.07-5.24), Charlson's comorbidity index 3 or higher (OR = 3.64, 95% CI 1.09-12.14), Association Research Circulation Osseous stage IV (OR = 2.16, 95% CI 1.03-4.54), reduced femoral offset (OR = 2.41, 95% CI 1.16-5.03), and a higher controlling nutritional status score (OR = 1.14, 95% CI 1.01-1.30) were independent risk factors of LWI. The nomogram had a concordance index of 0.773 and a Brier score of 0.049 in the training set, with corrected values of 0.747 and 0.051 after internal validation. The receiver-operating characteristic curve, calibration curve, Hosmer-Lemeshow test, and decision curve analysis all performed well in both the training and validation cohorts.

CONCLUSIONS

This study reported a 5.93% incidence of LWI and established a risk prediction model in patients undergoing THA for ONFH, supporting targeted screening and intervention to assist surgeons in assessing ambulation capacity and managing rehabilitation.

Patient Perception of Preoperative Nutrition and Recovery After Orthopaedic Surgery

BACKGROUND

Mounting evidence supports the use of nutritional supplementation to improve patient outcomes. The intent of this study was to utilize an anonymous questionnaire to determine patients' baseline knowledge, attitude, and belief regarding nutrition before total hip (THA) or total knee arthroplasty (TKA).

METHODS

After receiving Institutional Review Board approval, an anonymous questionnaire was administered to 300 patients, comprising 184 women (61.3%) and 116 men (38.6%), averaging 67 years (range, 39 to 89). There were 238 TKAs (79.3%), 12 revision TKAs (4%), 44 THAs (14.6%), and 6 revision THAs (2%).

RESULTS

Almost all (99.6%) subjects recognized the importance of preoperative nutrition. Most (83.0%) claimed that they knew what to eat preoperatively to optimize their surgical outcomes and expressed high levels of self-reported confidence (98.6%). Women were more likely to report having knowledge of preoperative nutrition (P = .05), and advanced education levels were linked to higher confidence (P = .002). Only 169 (56.3%) subjects reported knowing what supplements to take. When asked, 84% of subjects stated that they would purchase a nutrition program if recommended by their surgeon. Most studies show that an improved diet and appropriate supplementation can optimize nutritional status and potentially improve surgical outcomes.

CONCLUSIONS

The results of this study confirm that most patients do not know how to achieve optimal nutrition. Therefore, we believe there is a need for patient education on preoperative nutrition and its benefits.

Baseline Nutritional Status and Rehabilitation Progress in Individuals Requiring Inpatient Rehabilitation: A Retrospective Cohort Study

Objective

To evaluate the relationships between baseline nutritional status, medical events (MEs), and rehabilitation outcomes in individuals undergoing inpatient rehabilitation (IR).

Design

A retrospective single center cohort study.

Setting

An IR ward.

Participants

This study included 409 patients (mean age, 80 years; men, 170 [42%]) undergoing IR for hospital-associated deconditioning, neurologic disorders, or musculoskeletal diseases. Participants were grouped according to the Controlling Nutritional Status score at admission: normal nutrition (NN): 0 to 1, mild malnutrition (MM): 2 to 4, and moderate/severe malnutrition (M/SM): 5 to 12.

Interventions

None.

Main Outcome Measures

The primary outcomes included MEs leading to death or acute illness requiring transfer to other hospitals for specialized treatments. The secondary outcomes were the rehabilitation efficiency scores (changes in Functional Independence Measure [FIM] score divided by length of stay) for motor function (FIM-M) and cognitive function (FIM-C).

Results

Among the 409 participants, 300 (73%) were malnourished at admission. The adjusted hazard ratios (95% confidence interval) for MEs in the MM and M/SM groups relative to the NN group were 1.48 (0.67-3.27) and 0.98 (0.34-2.81), respectively. No significant differences were observed among the 3 groups in FIM-M efficiency scores (mean ± SD, NN: 0.49±0.51 vs MM: 0.41±0.57 vs M/SM: 0.44±1.06, P=.7) or FIM-C efficiency scores (0.04±0.06 vs 0.04±0.06 vs 0.08±0.4, P=0.1). Analysis of covariance showed no significant association between MM or M/SM group and FIM-M efficiency score (beta coefficient = -0.038, P=.6; beta coefficient = 0.15, P=.1, respectively) or FIM-C efficiency score (beta coefficient = 0.004, P=.8; beta coefficient = 0.047, P=.08, respectively).

Conclusion

No significant associations were observed between the baseline nutritional status and MEs, FIM-M efficiency score, or FIM-C efficiency score in individuals undergoing IR.

The Impact of Sarcopenia Risk on Postoperative Walking Independence in Older Adults Undergoing Total Joint Arthroplasty

BACKGROUND AND PURPOSE

Sarcopenia is known to be associated with poor outcomes after arthroplasty; however, no study has reported the relationship between sarcopenia and postoperative walking independence. This study aimed to determine the impact of sarcopenia risk screening using the SARC-CalF questionnaire and calf circumference on the time to walk independently after total hip or knee arthroplasty in older patients.

METHODS

We included 599 nonobese patients aged 65 years and older who underwent unilateral and primary total hip or knee arthroplasty. Preoperative sarcopenia risk was assessed using the SARC-CalF or calf circumference. The outcome of this study was the time to independent walking after surgery; it was calculated as the number of days from the date of surgery to the date when the patient was able to walk independently. The association between preoperative sarcopenia risk and time to independent walking after surgery was analyzed using Kaplan-Meier curves and Cox proportional hazards models.

RESULTS

Among the 599 patients undergoing total joint arthroplasty, 175 (29.2%) were determined to be at risk of sarcopenia using SARC-CalF and 193 (32.2%) using calf circumference. The Kaplan-Meier curve showed that sarcopenia risk assessed by SARC-CalF or calf circumference was associated with a prolonged time to independent walking in patients undergoing hip arthroplasty (log-rank test, P < .001 and P < .001, respectively). In patients undergoing hip arthroplasty, the Cox proportional hazards model showed that SARC-CalF score of 11 points and greater or a calf circumference less than the cutoff was a risk factor for delayed time to independent walking (hazard ratios: 0.55 and 0.57, P < .001 and P = .001, respectively). There was no association between preoperative sarcopenia risk and postoperative time to independent walking in patients who underwent knee arthroplasty.

CONCLUSIONS

Sarcopenia screening tools, such as SARC-CalF or calf circumference, should be useful for planning postoperative rehabilitation in older adults scheduled for hip arthroplasty. However, the accuracy of SARC-CalF or calf circumference measurement in patients scheduled for knee arthroplasty may be low.

Association of affected and non-affected side ability with postoperative outcomes in patients undergoing total hip arthroplasty

BACKGROUND

Although several reports have examined the association between preoperative function and postoperative outcomes in patients undergoing total hip arthroplasty (THA), it is unclear whether the ability of the affected or non-affected side particularly impacts on outcomes. We aimed to investigate the association between affected and non-affected side ability and walking independence.

METHODS

We prospectively enrolled 721 consecutive patients who underwent THA. Preoperatively, quadriceps isometric strength (QIS) and one-leg standing time (OLST) were measured. The endpoints were walking independence within 3, 5, 7, 10, and 14 days postoperatively. The associations between preoperative abilities and outcomes were examined using multivariate Cox hazard model, and the area under the curves (AUCs) for outcomes were compared.

RESULTS

We analysed 540 patients after excluding patients who met the exclusion criteria. Both affected and non-affected QIS predicted walking independence within 3 (p = 0.006 and 0.001, respectively), 5, 7, 10, and 14 (both p < 0.001) days postoperatively. For OLST, only the affected side did not predict walking independence within 3 days postoperatively (p = 0.154 and 0.012, respectively), and both sides did at days 5 (p = 0.019 and <0.001, respectively), 7, 10, and 14 (both p < 0.001). The AUCs of the non-affected side ability for walking independence were significantly greater than those of the affected side on postoperative days 3 (0.66 vs. 0.73; p = 0.021) and 5 (0.67 vs. 0.71; p = 0.040), with no significant difference after day 7.

CONCLUSIONS

Both sides abilities were associated with walking independence after THA, but non-affected side was found to be particularly crucial for early walking independence.

Effects of malnutrition on outcomes of patients with femoral head osteonecrosis undergoing total hip arthroplasty: A population-based study

BACKGROUND

This study aimed to evaluate the impact of malnutrition on in-hospital outcomes in patients undergoing total hip arthroplasty (THA) for osteonecrosis of the femoral head (ONFH).

METHODS

This population-based retrospective study extracted data of patients undergoing THA for ONFH in the US National Inpatient Sample between 2005 and 2018. Factors associated with in-hospital mortality, medical and surgical complications, unfavorable discharge, and prolonged hospital stay were determined by logistic regression analysis.

RESULTS

A total of 72,304 adults ≥18 years old with nontraumatic ONFH admitted for primary THA were included. Malnutrition was detected in 7152 (9.9%) patients using validated discharge codes. In-hospital mortality was 0.8% vs 0.1% for patients who were malnourished vs nonmalnourished. After adjusting for confounders, malnutrition was significantly associated with an increased risk of in-hospital death (adjusted odds ratio [aOR], 4.67; 95% CI, 2.43-8.97), medical complications (aOR, 1.49; 95% CI, 1.32-1.68), surgical complications (aOR, 1.78; 95% CI, 1.61-1.96), unfavorable discharge (aOR, 1.24; 95% CI, 1.11-1.39), and prolonged hospital stay (aOR, 1.90; 95% CI, 1.67-2.16) compared with adequate nutrition. Malnutrition was also associated with higher total hospital costs (adjusted β = $9620; 95% CI, 7.87-11.36). Furthermore, the association between malnutrition, any medical or surgical complications, and unfavorable discharge was stronger in patients younger than 50 years than those ≥50 years old.

CONCLUSIONS

In US patients undergoing primary THA for ONFH, malnutrition increases the risk of unfavorable in-hospital outcomes. This patient subgroup may require special attention and better strategies to improve perioperative care.

Association of preoperative nutritional status evaluated by the controlling nutritional status score with walking independence at 180 days postoperatively: a prospective cohort study in Chinese older patients with hip fracture

BACKGROUND

Malnutrition is significantly associated with unfavorable outcomes, but there is little high-level evidence to elucidate the association of malnutrition with losing walking independence (LWI) after hip fracture surgery. This study aimed to assess the association between preoperative nutritional status evaluated by the Controlling Nutritional Status (CONUT) score and walking independence at 180 days postoperatively in Chinese older hip fracture patients.

METHODS

This prospective cohort study included 1958 eligible cases from the SSIOS database. The restricted cubic spline was used to assess the dose-effect relationship between the CONUT score and the recovery of walking independence. Propensity score matching was performed to balance potential preoperative confounders, and multivariate logistic regression analysis was applied to assess the association between malnutrition and LWI with perioperative factors for further adjustment. Furthermore, inverse probability treatment weighting and sensitivity analyses were performed to test the robustness of the results and the Fine and Gray hazard model was applied to adjust the competing risk of death. Subgroup analyses were used to determine potential population heterogeneity.

RESULTS

The authors found a negative relationship between the preoperative CONUT score and recovery of walking independence at 180 days postoperatively, and that moderate-to-severe malnutrition evaluated by the CONUT score was independently associated with a 1.42-fold (95% CI, 1.12-1.80; P =0.004) increased risk of LWI. The results were overall robust. And in the Fine and Gray hazard model, the result was still statistically significant despite the apparent decrease in the risk estimate from 1.42 to 1.21. Furthermore, significant heterogeneities were observed in the subgroups of age, BMI, American Society of Anesthesiologists score, Charlson's comorbidity index, and surgical delay ( P for interaction < 0.05).

CONCLUSION

Preoperative malnutrition is a significant risk factor for LWI after hip fracture surgery, and nutrition screening on admission would generate potential health benefits.

[Nutritional, bone and body composition assessment of patients with knee and hip arthroplasty]

INTRODUCTION

malnutrition, both due to deficiency and excess of nutrients, is related to the morbidity of the surgical patient.

OBJECTIVES

to analyze the nutritional status, body composition and bone health of patients undergoing elective knee and hip arthroplasty.

METHODS

an observational cross-sectional study was carried out evaluating patients undergoing hip and knee replacement surgery from February to September 2019. The Malnutrition Universal Screening Tool (MUST), anthropometry, hand-grip dynamometry, bone densitometry, lumbar spine X-ray and bioimpedance analysis were performed.

RESULTS

eighty-six patients (61.6 % women) were evaluated, with a mean age of 69.5 ± 9.5 years. The mean body mass index (BMI) was 31.3 ± 4.5. According to MUST, 21.3 % were at risk of malnutrition; 16.9 % had decreased triceps skinfold with respect to p50 and 20 % had a pathological hand-grip dynamometry. In 91.4 %, vitamin D was < 30 pg/ml. In the bioimpedanciometry, the women presented significantly decreased muscle mass values. Age was correlated with a lower presence of fat-free mass, total and appendicular muscle mass. In those over 65 years of age, 52.6 % of men vs 14.3 % of women had a decreased muscle mass index; 58.5 % had low bone mineral density. We observed vertebral bone collapses in 13.9 %.

CONCLUSION

there is a high prevalence of obesity in patients who are candidates for arthroplasty and this does not exclude the existence of a risk of malnutrition. They may also have decreased muscle mass and strength. Nutritional education and physical exercise recommendations are essential in order to optimize nutritional status for surgery.

Moderate-to-Severe Malnutrition Identified by the Controlling Nutritional Status (CONUT) Score Is Significantly Associated with Treatment Failure of Periprosthetic Joint Infection

The prevalence and role of malnutrition in periprosthetic joint infection (PJI) remain unclear. This study aimed to use measurable nutritional screening tools to assess the prevalence of malnutrition in PJI patients during two-stage exchange arthroplasty and to explore the association between malnutrition and treatment failure. Our study retrospectively included 183 PJI cases who underwent 1st stage exchange arthroplasty and had available nutritional parameters, of which 167 proceeded with 2nd stage reimplantation. The recently proposed Musculoskeletal Infection Society (MSIS) Outcome Reporting Tool was used to determine clinical outcomes. The Controlling Nutritional Status (CONUT), Nutritional Risk Index (NRI), and Naples Prognostic Score (NPS) were used to identify malnutrition at 1st and 2nd stage exchange, respectively. Multivariate logistic regression analyses were performed to determine the association between malnutrition and treatment failure. Restricted cubic spline models were further used to explore the dose−response association. Additionally, risk factors for moderate-to-severe malnutrition were evaluated. Malnourished patients identified by CONUT, NPS, and NRI accounted for 48.1% (88/183), 98.9% (181/183), and 55.7% (102/183) of patients at 1st stage, and 9.0% (15/167), 41.9% (70/167), and 43.1% (72/167) at 2nd stage, indicating a significant improvement in nutritional status. We found that poorer nutritional status was a predictor of treatment failure, with CONUT performing best as a predictive tool. Moderate-to-severe malnutrition at 1st stage identified by CONUT was significantly related to treatment failure directly caused by PJI (odds ratio [OR] = 5.86), while the OR was raised to 12.15 at 2nd stage (OR = 12.15). The linear dose−response associations between them were also confirmed (P for nonlinearity at both 1st and 2nd stage > 0.05). As for total treatment failure, moderate-to-severe malnutrition as determined by CONUT was associated with a 1.96-fold and 8.99-fold elevated risk at the 1st and 2nd stages, respectively. Age ≥ 68 years (OR = 5.35) and an increased number of previous surgeries (OR = 2.04) may be risk factors for moderate-to-severe malnutrition. Overall, the prevalence of malnutrition in PJI patients is very high. Given the strong association between moderate-to-severe malnutrition identified by CONUT and PJI treatment failure, COUNT could be a promising tool to evaluate the nutritional status of PJI patients to optimize treatment outcomes.