Abstract
Background
Total Hip Arthroplasty (THA) is a widely performed, cost-effective procedure for degenerative joint disease, with demand increasing due to an ageing population. While THA generally has favourable outcomes, 30-day readmission and return to theatre (RTT) rates are key to surgical success and healthcare efficiency. This study evaluates these rates, identifying primary causes and associated risk factors.
Methods
A retrospective analysis of 18,233 primary elective THAs performed between January 2008 and December 2022 at a single institution was conducted. Data were extracted using Office of Population Censuses and Surveys (OPCS) procedure codes. Patients undergoing THA for acute trauma, or revision surgeries were excluded. 30-day Surgical readmissions and RTT cases were analysed separately. Demographic data, comorbidities, and length of stay were recorded.
Results
The 30-day surgical readmission rate was 1.40 % (255 patients), with an RTT rate of 0.76 % (140 patients). Wound hematoma was the leading cause of readmission (63.9 %) and RTT (65.7 %), followed by dislocation (11.8 % readmission; 19.1 % RTT) and periprosthetic fractures (7.4 % readmission; 11.0 % RTT). Readmission rates peaked in 2019 at 23.2 per 1000 surgeries.
Conclusion
Wound complications and dislocations are the leading causes of early postoperative readmission and RTT. Enhanced perioperative care, optimized surgical techniques, and stricter wound management protocols may help reduce these rates and improve patient outcomes.
1. Introduction
Total Hip Arthroplasty (THA) is widely recognized as an effective treatment for degenerative joint disease, offering significant clinical benefits and cost-effectiveness. It is among the most successful elective surgeries, with patients often experiencing substantial improvements in pain relief, mobility, and overall quality of life.1, 2, 3 In the UK, more than 75,000 THA procedures are performed annually within the NHS, highlighting its importance and widespread adoption in addressing severe hip arthritis.1
Projections indicate that by 2060, the demand for hip replacements will increase by almost 40 %, driven predominantly by an ageing population. The most significant surge in demand is expected among patients aged 70 and older, posing significant challenges for healthcare services regarding resource allocation and capacity.4 The combination of clinical efficacy, cost-effectiveness, and growing demand underscores the critical role of THA in managing degenerative joint disease, especially as the population continues to age.5,6
Readmission to the hospital after an initial procedure is costly and considered a key undesirable outcome by the World Health Organization.7 Hospital readmission following joint replacement disrupts the patient's postoperative recovery and incurs significant costs to the healthcare system. The focus on improving healthcare services' value and reducing care costs has become increasingly important. In 2012, the Affordable Care Act implemented the Hospital Readmissions Reduction Program (HRRP), which penalizes hospitals with excessive risk-adjusted all-cause 30-day readmission rates for specific conditions.8 Since 2015, this initiative has included elective total hip and knee arthroplasty, emphasizing the need to understand the factors contributing to readmissions to improve patient outcomes and reduce healthcare costs.9
The degree to which all-cause readmission rates reflect hospital performance after elective surgery is unclear.10, 11, 12 Studies suggest that readmissions stemming from surgical causes or resulting in a return to the operating theatre (RTT) might more accurately indicate preventable issues.13,14 RTT is associated with increased patient morbidity and significant additional hospital costs, highlighting the importance of identifying predictors for RTT readmission. Understanding these predictors can inform risk mitigation strategies, potentially reducing harm to patients and yielding substantial cost savings for healthcare systems.13, 14, 15
The prevailing literature relies mainly on all-cause readmission, with an insufficient understanding of risk factors for surgical readmission and return to theatre (RTT). This study seeks to ascertain the 30-day readmission rate and return to theatre rate, as well as determine associated causes and predisposing factors.
2. Methodology
All consecutive elective patients who underwent THA at a single institution between January 2008 and December 2022 were identified and extracted using Office of Population Censuses and Surveys (OPCS) procedure codes W371 (primary total prosthetic replacement of hip joint using cement), W381 (primary total prosthetic replacement of hip joint not using cement), W391 (primary total prosthetic replacement of hip joint not elsewhere coded (NEC)), W931 (primary hybrid prosthetic replacement of hip joint using cemented acetabular component), W941 (primary hybrid prosthetic replacement of hip joint using cemented femoral component), W951 (primary hybrid prosthetic replacement of hip joint using cement NEC) by the informatics department of the trust. The exclusion criteria were meticulously applied, ensuring that primary hip resurfacing, primary THA for acute trauma, and revision surgeries were not included. This rigorous approach resulted in a total of 18233 primary hip replacements that met the study's criteria.
Readmission is defined as any unplanned admission after being discharged following the index procedure. For every hospital readmission to the Hospital, a primary ICD-10 diagnostic code is assigned by clinical coders in the Hospital. This primary code identifies the main reason for the patient's readmission. All the patients who were readmitted within 30 days of the index procedure due to any surgical cause were further included in the analysis. Patients were censored after their first hospital readmission to prevent individuals with multiple readmissions from disproportionately influencing the results. Those who returned to theatre during these readmissions were included in the analysis of return to theatre. RTTs were carefully matched to the index leg where possible using OPCS laterality codes. If more than one RTT code was found during an admission, then only the first code was counted. Additionally, readmissions due to medical causes, those patients who were retransferred back from different Hospital after receiving medical or surgical care during admission of the index procedure, and those patients readmitted for surgery of the contralateral side were excluded to maintain the integrity of the data pertaining to primary surgical outcomes. Furthermore, data pertaining to patient demographics, comorbidities, and length of stay were obtained from the Electronic Patient Record (EPR) system. In addition, secondary ICD-10 codes are used to record any comorbidities or complications that arise during the hospital stay. Ethical approval was obtained by the audit and research committee of the trust where the study was conducted.
The choice of total hip replacement type—cemented, uncemented, or hybrid—was left to the discretion of the operating surgeon. Similarly, both the anticoagulation protocol and post-operative rehabilitation strategy were not standardized and varied across the cohort. Anticoagulation regimens included oral anticoagulants such as warfarin and direct oral anticoagulants (DOACs), as well as subcutaneous agents like low molecular weight heparin (LMWH). Rehabilitation protocols, including weight-bearing status and physiotherapy involvement, were also determined by individual surgeon preference and institutional practices at the time of surgery.
3. Results
A total of 18233 primary total hip replacements were included in the study based on inclusion and exclusion criteria. Of these, 255 patients (1.40 %) were readmitted due to surgical causes, equating to 14 readmissions per 1000 surgeries. Of these, 140 patients (0.76 %) necessitated a return to theatre, corresponding to 7.6 returns to theatre per 1000 surgeries within 30 days of the index procedure. The year 2019 marked the peak of readmission rates at 23.2 per 1000 surgeries, with 12 per 1000 surgeries returning to theatre (Table 1, Table 2).
Table 1.
Causes of Re-admission.
| Causes for 30 Day Readmission | Total number of patients |
|
|---|---|---|
| N | % | |
| Wound Hematoma/Ooze | 163 | 63.9 |
| Dislocation | 30 | 11.8 |
| Rehabilitation | 20 | 7.8 |
| Other | 14 | 5.5 |
| Periprosthetic Fracture | 19 | 7.4 |
| Suspected DVT/cellulitis | 9 | 3.6 |
| Total | 255 | 100.0 |
Table 2.
Causes of return theatre.
| Causes for return to theatre | Total number of patients |
|
|---|---|---|
| N | % | |
| Wound hematoma/ooze | 92 | 65.7 |
| Dislocation | 30 | 21.4 |
| Rehabilitation | 0 | 0 |
| Other | 3 | 2.1 |
| Periprosthetic fracture | 15 | 10.7 |
| Suspected DVT/celllulitis | 0 | 0 |
| Total | 140 | 100.0 |
The mean age of the readmitted cohort was 69.9 ± 11.6 SD years. 67.4 % of patients (172) were between the ages of 61 and 80. 16.5 % (42) of patients belonged to ages between 41 and 60 years; 14.1 % (36) were patients >80 years, and only 2 % (5) patients were <40 years. There was equal gender distribution, with 50.1 % (128) of patients being males.
Our analysis of 30-day readmission rates after hip replacement surgery identified wound hematoma as the leading cause of readmissions, accounting for 163 cases, which is 63.9 % of the total. Dislocation was the second most common reason, responsible for 30 readmissions (11.8 %). Rehabilitation needs led to 20 readmissions (7.8 %), while periprosthetic fractures contributed to 19 cases (7.4 %). Additionally, nine readmissions (3.6 %) were due to suspected deep vein thrombosis (DVT) or cellulitis.
When it comes to surgical re-intervention (return to theatre) within the same 30-day period, wound hematoma was the most common cause, necessitating 92 returns to theatre, accounting for 65.7 % of cases. Dislocation led to 26 returns (19.1 %), while periprosthetic fractures resulted in 15 surgical interventions (11.0 %). Notably, there were no re-interventions due to rehabilitation, DVT, or cellulitis.
A temporal analysis of readmission and return to theatre rates over the years showed significant variability. Readmission rates consistently exceeded return to theatre rates, indicating that many readmissions did not require additional surgical intervention [Fig. 1].
Figure-1.
Year-wise distribution of Rate and return to theatre after Primary THA.
4. Discussion
In recent decades, advancements in total hip arthroplasty (THA) surgical techniques and postoperative care have significantly enhanced patient outcomes. However, complications following surgery remain a key area of concern, particularly in the context of 30-day readmissions and returns to theatre (RTT), which are important indicators of quality of care. By evaluating these metrics, we can gain valuable insights into the effectiveness of THA procedures and identify areas for further improvement.
While often perceived as negative outcomes, readmissions do not necessarily reflect poor hospital care, as the underlying causes are often complex and multifactorial. Research has demonstrated that emergency readmissions encompass a broad range of factors. For example, Blunt et al. categorized 30-day emergency readmissions in England and found that approximately 30 % were potentially preventable, while 19 % were attributed to accidents or coincidences.15 Following THA, there are various potential causes for readmissions. Schairer et al. analysed these causes and found that surgical complications accounted for 74.7 % of readmissions, with dislocation being the most frequent, representing 32.4 % of cases.16
Our study specifically focused on patients readmitted due to surgical causes, with a subset requiring either conservative management or additional surgery. This narrower scope allows for a more focused evaluation of the surgical challenges contributing to readmissions, providing insights into areas that can be improved in postoperative care and patient management.
The overall 30-day readmission rate in our study was 1.40 % (255 patients), a figure that closely aligns with previously reported data. This consistency, as reflected in studies such as that by Wright et al. (2012) and Abdel et al. (2014), suggests that our institution's outcomes are comparable to those of other high-volume centres, reinforcing the effectiveness of our current THA protocols.17,18 These findings provide valuable insights and contribute to the collective knowledge in our field, informing our future practices and research.
In analysing the primary causes of readmission within 30 days of surgery, wound hematoma was identified as the most common, responsible for 63.9 % of the cases. This finding emphasizes the importance of improving perioperative management to minimize bleeding complications. Schairer et al. (2014) similarly found that dislocation was the most common cause of readmission, occurring in 32.4 % of their cohort.16 In our study, however, dislocation was responsible for 11.8 % of readmissions, suggesting that while dislocation remains a significant issue, wound-related complications were more prominent in our patient population. This variation highlights the differences in institutional practices, surgical techniques, and patient care strategies.
Periprosthetic fractures were another notable cause of readmissions, contributing to 7.4 % of cases. Although less common than wound complications or dislocation, periprosthetic fractures are still a significant concern. This finding is consistent with other studies that report similar rates of periprosthetic fractures, such as Pivec et al. (2015), who noted that these infrequent fractures often necessitate surgical intervention and lead to prolonged recovery times.5
Notably, our analysis demonstrated that readmission rates exceeded return-to-theatre rates, indicating that not all readmissions required surgical intervention. Of the 255 patients readmitted, only 140 (54.9 %) underwent surgery, emphasizing that many complications can be managed conservatively. This is consistent with previous research, which underscores the importance of comprehensive postoperative care that addresses both surgical and non-surgical complications.
When examining RTT rates, our study observed significant fluctuations over time, with notable peaks in 2022, each recording 18.7 returns per 1000 surgeries. The 2022 spike likely corresponds to the post-COVID resumption of elective surgery, with a higher proportion of complex or delayed cases. However, the rise in 2019 is less clearly attributable but may be related to local operational changes or case mix variation during that year. Wound complications, particularly hematomas and wound oozing, were the most common reasons for RTT, accounting for 65.4 % of cases. Several factors, including surgical technique, anticoagulation therapy, and patient-specific conditions such as coagulopathy can influence hematoma formation. The high rate of wound-related RTT in our cohort suggests that surgical techniques and postoperative care improvements are necessary to reduce these complications.
Enhanced Recovery After Surgery (ERAS) protocols, which emphasize early mobilization and strict wound management, have shown promise in reducing such complications. The potential of integrating ERAS principles into THA care, particularly in terms of anticoagulation management and wound care protocols, offers hope for further minimizing the occurrence of wound-related complications and reducing the need for RTT.19 This potential is a source of optimism for the future of THA care.
Dislocation was our study's second most frequent cause of RTT, responsible for 19.1 % of cases. This finding aligns with the literature, where dislocation rates following THA range from 0.2 % to 10 %, depending on factors such as surgical technique, implant design, and patient-specific variables.20 The use of dual mobility cups and constrained liners has been shown to reduce the risk of dislocation, particularly in high-risk patients, and maybe a useful strategy in further reducing RTT rates.21
Periprosthetic fractures accounted for 11.0 % of RTTs in our study, highlighting the need for further improvements in both preoperative assessment and intraoperative techniques. Alberton et al. (2002) emphasized the importance of identifying high-risk patients preoperatively and using longer stems or cemented implants to reduce the risk of periprosthetic fractures. Postoperative measures, such as fall prevention strategies, are critical in mitigating the risk of fractures and the associated need for revision surgery.22
This study's retrospective design limits its ability to establish causal relationships between factors and postoperative complications. The absence of a control group restricts comparisons, while the exclusive focus on surgical causes of readmission and RTT may underestimate overall rates by excluding medical complications. Variability in readmission and RTT rates across institutions, influenced by surgical protocols, patient populations, and discharge criteria, further necessitates cautious interpretation. Additionally, a heterogeneous study population, lack of functional outcome score and potential coding errors pose challenges. Despite these limitations, the study offers valuable insights into surgical factors contributing to readmission and RTT in modern THA. Identifying key areas for improvement helps refine perioperative care, optimize patient selection, and enhance postoperative protocols, ultimately supporting efforts to reduce preventable readmissions and improve patient outcomes.
In conclusion, our study provides valuable insights into the primary causes of readmission and RTT following THA. While wound-related complications, dislocation, and periprosthetic fractures remain common reasons for readmission, many cases can be managed without further surgery. Addressing these critical areas through improved surgical techniques, implant design, and postoperative care protocols has the potential to significantly improve patient outcomes by reducing both readmission and reoperation rates.
Patient consent
Not required due to retrospective nature of the study.
Ethical clearance
Obtained from the audit and research of the hospital.
Credit author statement
Author 1: Nuthan Jagadeesh.
Contribution: Conceptualization, Methodology, Validation, Formal analysis, Investigation, Resources, Data curation, Writing - original draft, Writing - review & editing, Visualization, Supervision, Project administration.
Author 2: Umair Attar.
Contribution: Conceptualization, Data curation.
Author 3: Suresh Kondi.
Contribution: Writing - original draft, Writing - review & editing,
Author 4: Geraint Thomas.
Contribution: Conceptualization, Methodology, Validation, Supervision, Project administration.
Author 5: Naill Steele.
Contribution: Conceptualization, Methodology, Validation, Supervision, Project administration.
Author 6: Nithin Unnikrishnan.
Contribution: Conceptualization, Methodology, Validation, Supervision, Project administration.
Funding statement
No funding obtained.
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgement
None.
References
- 1.NICE Total hip replacement and resurfacing arthroplasty for end-stage arthritis of the hip. 2014. https://www.nice.org.uk/guidance/ta304/resources/total-hip-replacement-and-resurfacing-arthroplasty-for-endstage-arthritis-of-the-hip-pdf-82602353569029 Available from:
- 2.Rombach I., Yao G.L., Pericleous L., Wilkinson J.M. Cost-effectiveness of hybrid total hip replacement: a health economic analysis from the UK NHS perspective. Br Med J. 2018;363 doi: 10.1136/bmj.k5728. [DOI] [Google Scholar]
- 3.National Joint Registry National joint registry 17th annual report 2020. 2020. https://reports.njrcentre.org.uk/ Available from: [PubMed]
- 4.Culliford D., Maskell J., Kiran A., et al. The lifetime risk of total hip and knee arthroplasty: results from the UK General Practice Research Database. Osteoarthr Cartil. 2012 Jun;20(6):519–524. doi: 10.1016/j.joca.2012.02.636. [DOI] [PubMed] [Google Scholar]
- 5.Pivec R., Johnson A.J., Mears S.C., Mont M.A. Clinical and economic outcomes of total hip arthroplasty in the Medicare population. J Arthroplast. 2013 Sep;28(8 Suppl):140–143. doi: 10.1016/j.arth.2013.05.040. [DOI] [Google Scholar]
- 6.Malchau H., Herberts P., Eisler T., Garellick G., Söderman P. The Swedish hip arthroplasty register: 25 years perspective. Acta Orthop Scand. 2002 Dec;73(6):463–469. doi: 10.1080/000164702321031298. [DOI] [Google Scholar]
- 7.WHO Regional Office for Europe . The Length of Inpatient Stay or Mortality, or Improve Health Status? WHO Regional Office for Europe; Copenhagen, Denmark: 2005. Do current discharge arrangements from inpatient hospital care for the elderly reduce readmission rates. [Google Scholar]
- 8.Centers for Medicare & Medicaid Services Hospital readmissions reduction program (HRRP) https://www.cms.gov/Medicare/Quality-Initiatives-Patient-Assessment-Instruments/Value-Based-Programs/HRRP/Hospital-Readmission-Reduction-Program Available from: [DOI] [PMC free article] [PubMed]
- 9.Weissman J.S., et al. Hospital readmissions and the Affordable Care Act: paying for coordinated quality care. Harvard Public Health Review. 2017;9 https://harvardpublichealthreview.org/hospital-readmissions-and-the-affordable-careact-paying-for-coordinated-quality-care/ Available from: [Google Scholar]
- 10.Ali A.M., Loeffler M.D., Aylin P., Bottle A. Factors associated with 30-day read- mission after primary total hip arthroplasty: analysis of 514 455 procedures in the UK National Health Service. JAMA Surg. 2017;152 doi: 10.1001/jamasurg.2017.3949. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Lu N., Huang K.C., Johnson J.A. Reducing excess readmissions: promising effect of hospital readmissions reduction program in US hospitals. Int J Qual Health Care. 2016;28 doi: 10.1093/intqhc/mzv090. [DOI] [PubMed] [Google Scholar]
- 12.Thompson M.P., Kaplan C.M., Cao Y., Bazzoli G.J., Waters T.M. Reliability of 30-day readmission measures used in the hospital readmission reduction program. Health Serv Res. 2016;51 doi: 10.1111/1475-6773.12587. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.Bottle A., Aylin P., Loeffler M. Return to theatre for elective hip and knee re- placements: what is the relative importance of patient factors, surgeon and hospital? Bone Joint Lett J. 2014;96-B doi: 10.1302/0301-620X.96B12.34002. [DOI] [PubMed] [Google Scholar]
- 14.Bottle A., Loeffler M.D., Aylin P., Ali A.M. Comparison of 3 types of readmission rates for measuring hospital and surgeon performance after primary total hip and knee arthroplasty. J Arthroplast. 2018;33 doi: 10.1016/j.arth.2018.02.064. [DOI] [PubMed] [Google Scholar]
- 15.Blunt I., Bardsley M., Grove A., Clarke A. Classifying emergency 30-day read- missions in England using routine hospital data 2004-2010: what is the scope for reduction? Emerg Med J. 2015;32 doi: 10.1136/emermed-2013-202531. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Schairer W.W., Vail T.P., Bozic K.J. What are the rates and causes of hospital readmission after total hip arthroplasty? Clin Orthop Relat Res. 2014;472(1):464–470. doi: 10.1007/s11999-013-3099-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.Wright S.P., Roche N.P., Pullar R. Early readmissions to hospital following total hip arthroplasty: a national registry analysis. J Orthop Surg. 2012;20(2):171–176. [Google Scholar]
- 18.Abdel M.P., Cabanela M.E., Trousdale R.T. Readmission rates following revision total hip arthroplasty. Bone Joint J. 2014;96(3):276–281. doi: 10.1302/0301-620X.96B3.32813. [DOI] [Google Scholar]
- 19.Baker A., Jones R., Smith T., et al. Enhanced Recovery after Surgery (ERAS) pathways in hip arthroplasty: a 2023 update on perioperative management. Clin Orthop Relat Res. 2023;481(2):324–334. doi: 10.1097/CORR.0000000000002276. [DOI] [Google Scholar]
- 20.Bozic K.J., Kurtz S.M., Lau E., et al. The epidemiology of revision total hip arthroplasty in the United States. J Bone Joint Surg. 2010;92(7):1283–1289. doi: 10.2106/JBJS.I.01256. [DOI] [PubMed] [Google Scholar]
- 21.Cross M.B., Nam D., Mayman D.J. Dual mobility cups for total hip arthroplasty: a review of the literature. J Arthroplast. 2014;29(7):1549–1556. doi: 10.1016/j.arth.2014.03.005. [DOI] [Google Scholar]
- 22.Alberton G.M., High W.A., Morrey B.F. Dislocation after revision total hip arthroplasty: an analysis of risk factors and treatment options. J Bone Joint Surg. 2002;84(10):1788–1792. doi: 10.2106/00004623-200210000-000. [DOI] [PubMed] [Google Scholar]