1 Introduction

Osteoarthritis of the knee is a prevalent and debilitating condition affecting a substantial portion of the global population, particularly in the middle-aged and elderly demographic 1. As a therapeutic response to the functional limitations and chronic pain associated with knee osteoarthritis, total knee replacement (TKR) has emerged as a widely adopted surgical intervention 2. Traditionally performed as an inpatient procedure with a standard hospital stay, recent advancements in medical practices and surgical techniques have paved the way for exploring the feasibility and safety of total knee replacement (TKR) 3.

Total knee replacement has long been established as an effective intervention to alleviate pain and improve the quality of life for individuals suffering from advanced knee osteoarthritis 4. Day case procedures not only reduce the economic burden on healthcare systems but also offer the advantage of quicker recovery and enhanced patient satisfaction 5. Despite the success of day case approaches in various surgical domains, the application of this model to total knee replacement is a nuanced and evolving area of investigation. Day case total knee replacement poses unique challenges, including the need for effective pain management, optimized surgical protocols, and comprehensive preoperative and postoperative care. Addressing these challenges requires a multifaceted examination of patient demographics, perioperative details, and postoperative outcomes to ascertain the safety, efficacy, and patient experience associated with day case total knee replacement. Through a thorough investigation of demographics, procedural nuances, and postoperative outcomes, this study aspires to contribute valuable evidence to the ongoing discourse on the evolving landscape of knee replacement surgery.

2 Methodology

This study employed a retrospective observational design to investigate the outcomes of day case total knee replacement. Ethical approval was obtained from the institutional review board before commencing data collection, ensuring adherence to ethical standards and patient confidentiality.

The study included patients who underwent day case total knee replacement at a tertiary care center in Riyadh, Saudi Arabia. Inclusion criteria comprised individuals with a diagnosis of advanced knee osteoarthritis warranting total knee replacement. Patients with contraindications to day case surgery or those requiring additional medical monitoring were excluded.

Patient demographics, including age, gender, weight, height, and body mass index (BMI), were extracted from electronic health records. Baseline characteristics, such as the Generalized Anxiety Disorder (GAD) score, Physical Component Summary (PCS) score, and laboratory values (Vitamin D, B12, Calcium), were recorded. Operative details encompassed the type of anesthesia (spinal or general), volume of fluids administered, and specifics related to tourniquet management. Procedural times, including total surgery time, recovery time, and length of stay, were documented. Blood pressure measurements on discharge, both systolic and diastolic, were recorded. Postoperative outcomes were assessed using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the Short Form Health Survey (SF-36). WOMAC scores, measuring pain, stiffness, and physical function, were recorded preoperatively and at six weeks and three months postoperatively. SF-36 scores, evaluating physical and mental health, were also collected at these time points. Pain and nausea/vomiting presentations were monitored at different intervals, including recovery, ward stay, discharge, and postoperative days 1, 2, 3, 4, 5, and 14. Pain scores were measured on a numerical scale, and the incidence of nausea and vomiting was recorded.

Descriptive statistics, including means and standard deviations, were calculated for continuous variables. Categorical variables were presented as frequencies and percentages. Paired t-tests were employed to assess the significance of differences in WOMAC and SF-36 scores between preoperative and postoperative time points. For pain and nausea/vomiting analyses, mean differences were computed, and paired t-tests were utilized to determine the significance of changes compared to the baseline (postoperative day 1). Categorical data were presented as percentages. All statistical analyses were conducted using SPSS version 26, with a significance level set at p < 0.05. The results are reported as mean (SD), mean diff (95 % CI), p-value, or percentage, as appropriate.

3 Results

The majority of participants were female, constituting 87.5 % of the cohort, while 12.5 % were male. The mean age of the patients was 59.38 years (SD = 8.26). Additionally, the mean weight, height, and body mass index (BMI) were 72.54 kg (SD = 13.11), 1.61 m (SD = 0.05), and 27.81 kg/m2 (SD = 4.56), respectively. The distribution of BMI categories revealed that 12.5 % were classified as normal weight, 50.0 % as overweight, and 37.5 % as obese (Table 1).

The GAD (Generalized Anxiety Disorder) score reveals a mean of 2.63 with a standard deviation of 2.26 while PCS (Physical Component Summary) score, a measure of physical health-related quality of life, exhibits a mean of 5.63 with a tight standard deviation of 1.06. Laboratory values are also detailed, with mean Vitamin D levels at 77.75 (SD = 34.16), B12 levels at 403.43 (SD = 166.85), and Calcium levels at 2.24 (SD = 0.07). Hemoglobin levels are crucial indicators of patients' pre-operative and post-operative health. The mean Hemoglobin Level Pre-op is 13.64 (SD = 0.81), and the mean Hemoglobin Level Post-op is 13.15 (SD = 1.18). The Difference in Hemoglobin, calculated as the post-operative value minus the pre-operative value, shows a mean decrease of 0.49 (SD = 0.98), which, while statistically significant, is within an acceptable range for patients undergoing this type of surgery (Table 2).

Moreover, 62.5 % of the patients received spinal anesthesia and 37.5 % of them received general anesthesia (GA) (Table 3). The Volume of Fluid administered during the procedure is reported with a mean of 762.50 L (SD = 256.00) while the Volume of Block administered, specifically the anesthesia block, is reported at a mean of 40.00 L. The Inflation and Deflation of Tourniquet, critical for blood flow control during surgery, are detailed with mean values of 499.63 L (SD = 542.10) and 830.13 L (SD = 536.52), respectively. Total Tourniquet Time, encompassing both inflation and deflation phases, is presented with a mean of 330.50 min (SD = 670.19). Operative time parameters include Total Surgery Time, with a mean of 82.50 min (SD = 26.59), and Total Recovery Time, indicating the time from the end of surgery to recovery, with a mean of 53.00 min (SD = 23.28). The Length of Stay, a critical postoperative metric, is reported with a mean of 847.50 min (SD = 393.36). Blood pressure measurements on discharge, crucial for assessing immediate postoperative stability, are detailed as Systolic Blood Pressure with a mean of 125.88 mmHg (SD = 5.59) and Diastolic Blood Pressure with a mean of 92.88 mmHg (SD = 6.90) (Table 4).

The WOMAC scores, measuring pain, stiffness, and physical function, exhibit a substantial improvement from a mean pre-operative value of 44.27 (SD = 9.88) to 19.53 (SD = 4.58) at the six-week follow-up and 6.51 (SD = 3.6) at the three-month follow-up. Paired t-test results reveal highly significant differences compared to pre-operation, with p-values of 0.000∗.

Similarly, the SF-36 scores, which assess physical and mental health across various domains, demonstrate noteworthy enhancements. Physical functioning scores increase from a pre-operative mean of 40 (SD = 5.35) to 90.63 (SD = 10.5) at six weeks and 95.63 (SD = 4.96) at three months. Other domains, including role functioning/physical, role functioning/emotional, energy/fatigue, emotional well-being, social functioning, pain, general health, and health change, all exhibit substantial improvements at both follow-up time points. Paired t-test results consistently show statistical significance (p < 0.05) for all domains except for role limitations due to physical health or emotional health where no significant difference was reported (Table 5).

During the Recovery period, immediately postoperatively, the mean pain score is reported as 0, indicating minimal pain, with no standard deviation. Nausea and vomiting are reported in 12.5 % of patients during this phase. Similarly, in the Ward and Discharge phases, the mean pain score remains at 0, emphasizing effective pain management during these recovery stages. Nausea and vomiting remain consistent at 12.5 % during both phases. On Day 1 postoperatively, patients experience a mean pain score of 0.63 (SD = 0.74), establishing a baseline reference. Additionally, 25 % of patients report nausea, while 75 % remain free from vomiting. Subsequent days demonstrate an interesting trend. On Day 2, the mean pain score increases to 1.63 (SD = 0.92), with a statistically significant mean difference of −1.0 (95 % CI: 1.8 to −0.22, p = 0.018∗), reflecting an increase in pain compared to Day 1. Nausea and vomiting percentages remain constant at 25 %. However, from Day 3 onwards, there is a notable decrease in mean pain scores, reaching 2.63 (SD = 1.77) on Day 3 and stabilizing around 2.75 to 3 in subsequent days. The paired t-test results continue to show statistically significant mean differences, underscoring the effectiveness of pain management strategies. However, from Day 3 onwards, there is a notable decrease in mean pain scores, reaching 2.63 (SD = 1.77) on Day 3 and stabilizing around 2.75 to 3 in subsequent days. The paired t-test results continue to show statistically significant mean differences, underscoring the effectiveness of pain management strategies (Table 6).

4 Discussion

The findings presented in this study shed light on various facets of day case total knee replacement, encompassing demographic characteristics, preoperative health status, procedural details, and postoperative outcomes. The demographic profile of the patients undergoing day case total knee replacement revealed interesting patterns. The predominance of female participants, constituting 87.5 % of the cohort, aligns with the well-documented higher prevalence of knee osteoarthritis in women [^1,6–8]. The mean age of 59.38 years indicates that this procedure is relevant for a middle-aged population. Additionally, the distribution of BMI categories, with 50.0 % classified as overweight and 37.5 % as obese, underscores the association between excess body weight and the need for knee replacement [^9–11].

The preoperative health assessment, including the GAD and PCS scores, provides insights into the mental and physical well-being of the patients. The relatively low GAD score (mean = 2.63) suggests a modest level of generalized anxiety, which may be attributed to the anticipation of surgery. The PCS score, reflecting physical health-related quality of life, exhibits a mean of 5.63, indicating a baseline level of physical functioning. These scores, in conjunction with laboratory results, including Vitamin D, B12, and Calcium levels, contribute to the holistic understanding of patients' health before the surgical intervention.

In addition, the current study outlines various operational characteristics of day case total knee replacement, shedding light on the procedural intricacies. The choice of anesthesia is crucial in day case surgeries, and our findings indicate that 62.5 % of patients received spinal anesthesia, while 37.5 % received general anesthesia. This distribution suggests a preference for regional anesthesia, aligning with the goal of facilitating a quicker recovery and minimizing postoperative complications 12.

Moreover, the study delves into the postoperative outcomes, focusing on WOMAC and SF-36 scores at different intervals. The WOMAC scores, encompassing pain, stiffness, and physical function [^13,14], reveal substantial improvements at the six-week and three-month follow-ups. The statistically significant differences, as indicated by paired t-test results, underscore the efficacy of day case total knee replacement in enhancing patients' functional status and alleviating pain which also reported in the literature [^15–17].

The SF-36 scores exhibit notable enhancements across various domains, including physical functioning, energy/fatigue, emotional well-being, and social functioning. The consistent statistical significance in paired t-tests attests to the sustained positive impact of the procedure on multiple aspects of health-related quality of life [^18–20]. Notably, the absence of significant differences in role limitations due to physical or emotional health may indicate that day case total knee replacement does not substantially affect patients' roles in these domains [^21–23]. This nuanced understanding is crucial for managing patient expectations and providing comprehensive preoperative counseling.

Furthermore, the results showed that the postoperative pain experience and the occurrence of nausea and vomiting at different intervals. The immediate postoperative period is characterized by minimal pain, effectively managed through pain management strategies [^24–26]. Nausea and vomiting, reported in 12.5 % of patients during the recovery, ward, and discharge phases, may be attributed to the residual effects of anesthesia but appear to be transient [^27,28]. The increase in mean pain scores on Day 2 is noteworthy, with a subsequent decrease in the following days. The statistically significant differences in paired t-tests emphasize the effectiveness of pain management strategies postoperatively. Importantly, the complete resolution of nausea and vomiting from Day 3 onwards suggests successful intervention and patient adaptation to the surgical procedure.

Despite the comprehensive nature of this study, several limitations should be acknowledged. The sample size is relatively small, and the study's single-center design may limit the generalizability of the findings. Additionally, the absence of a control group hinders the comparison of outcomes with traditional knee replacement approaches. Future research could explore long-term outcomes, patient satisfaction, and cost-effectiveness in a larger and more diverse cohort.

In conclusion, this study provides a detailed examination of day case total knee replacement, spanning demographic characteristics, preoperative health status, procedural details, and postoperative outcomes. The findings suggest that this approach is feasible and associated with significant improvements in functional status, pain relief, and health-related quality of life. The meticulous analysis of operational parameters and postoperative recovery highlights the success of pain management strategies and the overall safety of the procedure.

Patient's consent

The authors certify that all appropriate patient consent forms were obtained. The patients understand that their names and initials will not be published, and all efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Ethical consideration

The research was carried out in accordance with the principles described in the Declaration of Helsinki. The study was conducted in accordance with the institutional committee's and the ethical board's approvals.

Author contribution

Bashir R. Alenazi: Conception and design of study, Formal analysis and interpretation of data, Drafting the manuscript, Revising the manuscript. Ghassan H. Hakeem: Conception and design of study, Formal analysis and interpretation of data, Drafting the manuscript, Revising the manuscript. Mohammed A. Alruwaili: Conception and design of study, Formal analysis and interpretation of data, Drafting the manuscript, Revising the manuscript. Saad I. Alshammari: Conception and design of study, Formal analysis and interpretation of data, Drafting the manuscript, Revising the manuscript. Sayaf H. Alshareef: Conception and design of study, Formal analysis and interpretation of data, Drafting the manuscript, Revising the manuscript. Saeed S. Alzahrani: Conception and design of study, Formal analysis and interpretation of data, Drafting the manuscript, Revising the manuscript.

Funding

None.