Improving day surgery rates of anterior cruciate ligament reconstruction surgery in surgical units not dedicated to performing day surgery

Background and aims: Current guidance advises that at least 90% of anterior cruciate ligament reconstructions are performed as day-case operations. Same-day surgery rates achieved by surgical units have significant clinical and financial implications. The primary aim of this multi-centre study was to determine the rate of admission and causes for admissions in patients undergoing anterior cruciate ligament reconstruction. Method: Patient documentations were studied for those who underwent an elective anterior cruciate ligament reconstruction between January 2015 and April 2019. Contributing factors related to admission length were investigated and included patient age, gender, body mass index (BMI), operating surgeon, operating hospital, American Society of Anaesthesiology (ASA) grade, and position of the patient on the operating list. Both univariate and multivariate analysis were conducted using the STATA/IC 16.1 statistical package. Results: The day surgery rate of anterior cruciate ligament reconstructions were 52% (50/95). Patients positioned later on the operating list were more likely to be admitted post-operatively (OR, 4.49; P = .002; 95% CI, 1.72-11.69) and this was the only factor associated with admission. A large majority of admitted patients (95.6%) were admitted without a clinical cause and were otherwise safe for same-day discharge. Conclusions: The day surgery rate for ACL reconstruction remains low, despite an extremely low complication rate. Reconfiguration of the operating lists and positioning anterior cruciate ligament reconstructions earlier in the day will likely increase the same-day discharge rate and reduce associated costs.


| INTRODUCTION
The British Association of Day Surgery (BADS) directory publishes surgery-specific discharging goals and advise that at least 90% of patients who undergo an anterior cruciate ligament (ACL) reconstruction should be discharged on the day of operation. 1An ACL reconstruction has a very low surgical complication rate and patients do not routinely require hospital admission. 2An outpatient ACL reconstruction care pathway was conducted with 222 patients without any short or long-term complications attributable to prompt discharge. 3A prospective comparative study found that 98.6% of ACL patients discharged on the day of the operation did not have complications, significant post-operative pain or poor satisfaction. 4[9] Increasing day surgery rates, are in part secondary to advancements in anaesthesia conferring improved analgesic control.In patients undergoing a hamstring or patella tendon harvest, regional blocks (hamstring and adductor canal blocks) have demonstrated improved post-operative pain control and facilitate early discharge. 10,11om a financial perspective, ACL reconstructions performed as a day-case procedure produce cost savings of up to 58% compared to inpatient surgery. 10These savings are significant given the incidence of ACL injuries (14.5/100000 per year in the Edinburgh Orthopaedic Trauma Unit) and the high cost of performing the procedure. 9,12Additional advantages include reduced bed pressure, reduced hospitalacquired infection rate and lower waiting times. 7spite the advantages, health boards fail to meet the target set out by BADS.A database analysis from NHS England containing 13 941 ACL reconstructions between 2008 and 2010 found that only 20% were performed as day cases. 2Poor management and coordination between surgeons, anaesthetists and allied healthcare professionals were highlighted as contributing factors.Further causes include post-operative nausea and vomiting (PONV), pain management concerns, anaesthetic complications and social issues such as difficulty acquiring home transport.
The aim of this study was to establish the same-day discharge rate of ACL reconstructions performed between January 2015 and April 2019 across three surgical units and to determine the causes of admissions.All three units were not dedicated day surgery facilities and the ACL patients were operated on surgical lists containing inpatients receiving other elective procedures.The secondary aim was to determine the reasons for admission in the patient cohort.In this study, day surgery was defined as discharge on the same day as the operation (not discharge within 24 hours of the operation) and is consistent with the definition of day surgery within the UK literature.
Restructuring of surgical lists, technological developments in surgical equipment and improved efficiency of clinical pathways are associated with improved day surgery rates.It was hypothesized that scheduling a patient's ACL reconstruction earlier in the day would improve the day surgery rate. 1 Earlier surgery would correspond to a longer post-operative period for physiotherapy assessment, medical review and discharge planning.It would permit medical staff additional time to manage complications such as PONV and significant post-operative pain.

| Population cohort
Data were collected retrospectively from a regional database containing patients who underwent an elective ACL reconstruction between January 2015 and April 2019.Within our region, there are three surgical units (one tertiary unit and two secondary units), each of which perform ACL reconstructions.A total of eight consultant orthopaedic surgeons perform ACL reconstructions across the three units, all of which had a specialist interest in ACL reconstruction.The surgical units were located in a defined geographical region with a stable population of more than 416 090 people, based on mid-year 2017 population estimates, and less than a 1% migration rate. 13The patient's operation slot was assigned according to elective operating lists, each comprised of various other elective orthopaedic operations.Since the surgical units were not dedicated day surgery units, post-operatively, all patients were assessed in the recovery room before being transferred to a general orthopaedic elective ward until discharge.Patients who received emergency ACL operations were excluded from the analysis.

| Data
Prior to data collection, an application was made to the regional "Information Governance Service" and ethical approval was granted by the Data Protection Officer.Following this, all data were collected retrospectively using the following electronic databases: "Clinical Portal," Electronic Discharge Documents (EDDs), theatre operating lists and anaesthetic pre-assessment documents.Patients were tracked between electronic record systems using a unique patient identifier called a "Community Health Index" (CHI) number and the data from each patient was documented on a secure electronic database.
For each patient, the following variables were collected: patient age (years), gender, BMI, operating surgeon, operating hospital, ASA score (an assessment of overall fitness), distance from hospital to home postcode (km), pre-operative admissions (y/n), previous knee surgery (y/n), time from injury to operation (months), length of admission (days), and position of the patient on the operating list.Electronic documents from the databases were used to establish the rate of short-term surgical complications during admission and any additional operations performed on the ipsilateral knee during the same arthroscopy (eg, meniscal repair and posterior cruciate ligament reconstruction).

| Data analysis
The patients were split into two groups: those discharged on the day of operation and those admitted post-operatively.The listed variables were compared between the admitted and discharged patient groups.
All variables were assumed to be non-parametric and as such all variables were compared using the Mann-Whitney U test and a two-tailed P value was generated.During analysis, the absolute and relative operating list position were considered-the relative list position determined the list position relative to the list length to account for variation in list length.Chi-squared tests were used to compare patient gender, the likelihood of undergoing an additional procedure, surgical units and individual orthopaedic consultant surgeons between the admission and discharge groups.Multivariate logistic regression analysis was used to assess the association of patient admission with the following variables: age ≥ 26 years (median age), male gender, BMI ≥ 25 kg/m 2 , additional procedures performed and absolute operating list position ≥3.A second regression analysis was repeated with the "relative operating list position ≥0.5," in place of the "absolute operating list position ≥3" variable.All statistical tests were carried out using the Stata/IC 16.1 statistical software package.
Our study has adhered to the STROBE checklist for a cohort study (Data S1).

| RESULTS
Ninety-five patients met the inclusion criteria (69% male; median age, 26 years).Forty-nine patients (51.6%) were discharged on the same day of surgery and the remaining 46 patients (48.4%) were admitted overnight and discharged the following day.Of those admitted, two patients (4.0%) had a clinical reason for admission; one patient had significant post-operative pain and one patient had a large amount of wound discharge.The remaining 44 patients (96%) were admitted without a reason stated for admission.Patient characteristics are displayed in Table 1 and variables are compared between groups.
The median absolute operating list position for the discharge and admission group was 1 and 2, respectively (P = .016).The median relative operating list position for the discharge group and admission group was 0.40 and 0.63, respectively (P = .0023).There was no significant difference in the rate of discharge between the three surgical units (P = .56)or between the eight consultant orthopaedic surgeons (P = .63).
A logistic regression was conducted with the following binary variables: patient age ≥ 26 years, male gender, BMI ≥ 25 kg/m 2 , additional procedures performed and the absolute position ≥3 on the operating list (Data S2).All admitted patients had an ASA score of 1 and this variable was excluded from the model.Being positioned third or later on the operating list was the only significant variable in this model that was associated with admission (OR, 4.49; P = .002;95% CI, 1.72-11.69).In the second regression, being placed in the middle position or later (relative position ≥0.5) was the only variable associated with patient admission (OR, 3.77; P = .003;95% CI, 1.57-9.06;Data S3).

| DISCUSSION
Fifty-one percent of patients were discharged on the same day of surgery.This is significantly below the target set by BADS (90%).An overnight stay in hospital costs approximately £300, and our results would indicate that there is significant potential for savings granted the same-day discharge rate improves.Of those admitted, only 4.3% were admitted with a clinical explanation. 2Furthermore, the rate of PONV or post-operative pain was extremely low in the present patient cohort and consistent with the literature. 4[16] Reconfiguration of the operating lists and prioritizing day surgery cases early in the day where possible could improve the same-day discharge rate.Locally, the operating lists were made up of a mixture of patients undergoing ACL surgery and joint replacement orthopaedic procedures.The joint replacement procedures were frequently positioned earlier than ACL reconstructions.Patients receiving hip and knee replacements are invariably admitted for overnight stay and do not require an early operation to facilitate same-day discharge.These patients can be placed later the operating list to free up list space earlier in the day for day-surgery cases.This finding is applicable to all day-surgery cases, even of other surgical specialties, where the cases are combined with overnight cases on the same surgical list.This principle not be applied to operative lists made up of entirely day surgery cases, whereby prioritizing some day surgery cases would simply delay other surgical cases.

T A B L E 1 Overview of patients
Locally the ACL patients were not managed within dedicated day surgery units or on a dedicated day surgery operating list, but instead the ACL patients were managed according to a standard lower limb inpatient pathway.Management of each patient as a "day case" was not the default management and a streamlined day surgery pathway was not adopted. 7The integrated structure between day cases and inpatients reduces the emphasis on same-day discharge and the need to meet the discharge target. 14This was the case across all three surgical units and could explain the low same-day discharge rates across the region.A dedicated day surgery list would help differentiate day surgery patients from the inpatient care pathway and promote the fulfilment of the day-case discharge criteria.
Patient expectations and their pre-operative perceptions of postoperative recovery and pain management were not explored in this study.These are recognized concerns regarding the discharge of ACL reconstruction patients and are likely contributing factors. 7Managing patient expectations begins pre-operatively through the provision of relevant information and giving patients sufficient time to make informed decisions. 15Thorough patient counselling in clinic can manage these expectations and prepare patients for day surgery.
The results of this study are limited by the small patient cohort and the biases of a retrospective study including loss to follow-up and selection bias.A larger cohort would help identify a possible relationship with factors such as age, BMI, comorbidities and additional surgery.For example, it is reasonable to suspect that patients undergoing additional procedures such as a posterior cruciate reconstruction have a greater risk of surgical complications or significant post-operative pain.Despite the sample size, the significant finding should prompt surgical units that are not dedicated day surgical units to reconfigure their elective operating lists to improve sameday discharge.Although exposed to the selection bias and loss to follow-up of a retrospective cohort study, these biases are unlikely to impact the significance of the major finding of this study and the relationship between list position and same-day discharge is likely to be valid.
Patients positioned last on the operating list were over five times more likely to be admitted than those positioned earlier.Late operating list position demonstrated a strong association with hospital admission, and this relationship persisted once adjusting for variation in list length.A late arrival time to the ward postoperatively allocates less time to plan for safe discharge.In our surgical unit, post-operative physiotherapy consultation, medical review and discharge planning including optimizing discharge medications and arranging transport are required prior to discharge.Other discharge criteria include, successful voiding of urine, managing oral intake and a minimum of a four-hour observation period postanaesthetic.If the discharge criteria are not met then patient overnight admission is deemed necessary, despite the patient being