Re-admissions, re-operations and length of stay in hospital after aseptic revision knee replacement in Denmark: a two-year nationwide study

Revision Total Knee Arthroplasty With an Imageless, Second-Generation Robotic System

BACKGROUND

Robotic-assisted total knee arthroplasty is increasingly used in revision total knee arthroplasty (rTKA), with imageless systems recently receiving Food and Drug Administration (FDA) approval. However, there remains a paucity of literature on the use of robotic assistance in revision total knee arthroplasty (TKA). This paper describes the imageless surgical technique for robotic revision TKA using a second-generation robotic system and details both intraoperative and 90-day outcomes.

METHODS

This was a retrospective review of 115 robotic revision TKAs from March 2021 to May 2023 at 3 tertiary academic centers. Patient demographics, perioperative surgical data, and 90-day outcomes were collected. Pain and Patient-Reported Outcomes Measurement Information System scores preoperatively and postoperatively were recorded. All-cause reoperations at the final follow-up were detailed. The mean patient age was 65 years (range, 43 to 88), and 58% were women. The mean follow-up time was 13 months (range, 3 to 51).

RESULTS

The most common indications for rTKA were instability (n = 37, 32%) and aseptic loosening (n = 42, 37%). There were 83 rTKAs to a posterior-stabilized liner, 22 to a varus-valgus constrained liner, and 5 to a hinged construct. The median polyethylene size was 11 (interquartile range, 10 to 13), and 93% of patients had their joint line restored within 5 millimeters of the native contralateral knee. Within the 90-day postoperative window, there were 8 emergency department visits and 2 readmissions. At the final follow-up, there were 5 reoperations and 2 manipulations under anesthesia. There were 4 patients who required irrigation and debridement after superficial wound dehiscence, and one had an arthrotomy disruption after a fall.

CONCLUSIONS

This review demonstrates favorable intraoperative and 90-day outcomes and suggests that imageless robotic surgery is a promising modality in rTKA. Further studies comparing the longitudinal outcomes after robotic and conventional rTKA are warranted.

Prediction of suitable outpatient candidates following revision total knee arthroplasty using machine learning

Aims

To identify variables independently associated with same-day discharge (SDD) of patients following revision total knee arthroplasty (rTKA) and to develop machine learning algorithms to predict suitable candidates for outpatient rTKA.

Methods

Data were obtained from the American College of Surgeons National Quality Improvement Programme (ACS-NSQIP) database from the years 2018 to 2020. Patients with elective, unilateral rTKA procedures and a total hospital length of stay between zero and four days were included. Demographic, preoperative, and intraoperative variables were analyzed. A multivariable logistic regression (MLR) model and various machine learning techniques were compared using area under the curve (AUC), calibration, and decision curve analysis. Important and significant variables were identified from the models.

Results

Of the 5,600 patients included in this study, 342 (6.1%) underwent SDD. The random forest (RF) model performed the best overall, with an internally validated AUC of 0.810. The ten crucial factors favoring SDD in the RF model include operating time, anaesthesia type, age, BMI, American Society of Anesthesiologists grade, race, history of diabetes, rTKA type, sex, and smoking status. Eight of these variables were also found to be significant in the MLR model.

Conclusion

The RF model displayed excellent accuracy and identified clinically important variables for determining candidates for SDD following rTKA. Machine learning techniques such as RF will allow clinicians to accurately risk-stratify their patients preoperatively, in order to optimize resources and improve patient outcomes.

Patient-Reported Outcomes and Satisfaction 1 to 3 Years After Revisions of Total Knee Arthroplasties for Unexplained Pain Versus Aseptic Loosening

BACKGROUND

It is unknown if patients are relieved of pain after knee arthroplasty revision for unexplained pain. The aim of this cross-sectional case-control study was to compare patient-reported outcome measures (PROMs) and satisfaction 1 to 3 years after revision of total knee arthroplasties (TKAs) for the indications of unexplained pain versus aseptic loosening.

METHODS

We included 384 patients undergoing TKA revision for the indications of unexplained pain and aseptic loosening from January 1, 2018 to December 31, 2020 from the Danish Knee Arthroplasty Register. A total of 81 patients were revised for unexplained pain and 303 for aseptic loosening. Questionnaires including PROMs (Oxford Knee Score, EQ-5D-5L, and Forgotten Joint Score) and satisfaction with the surgery on a 0-100 scale (100 = not satisfied; 0 = very satisfied) were sent to digitally secured mailboxes. Time from revision to data collection was a median 3.1 years (range, 1.4-4.4 years).

RESULTS

Median Oxford Knee Score was 25 (interquartile range [IQR] 15) versus 31 (IQR 18) 1-3 years after revisions for unexplained pain versus aseptic loosening, P = .009. Median EQ-5D-5L was 0.6 (IQR 0.4) versus 0.8 (IQR 0.3) for unexplained pain versus aseptic loosening, P = .009. Median Forgotten Joint Score was 50 (IQR 7) versus 50 (IQR 16) for unexplained pain versus aseptic loosening, P = .905. Satisfaction was 75 (IQR 38) for unexplained pain and 50 (IQR 73) for aseptic loosening, P < .001.

CONCLUSION

Patients undergoing TKA revision for the indication of unexplained pain had worse results on PROMs than those revised for aseptic loosening. Likewise, patients revised for unexplained pain were less satisfied compared to patients revised for aseptic loosening. This information is valuable to both surgeons and patients when candidates for revision surgery are selected, to obtain the best possible outcomes.

Patient safety in distal femoral resection knee arthroplasty for non-tumor indications: a single-center consecutive cohort study of 45 patients

BACKGROUND

Distal femoral resection knee arthroplasty may be a viable option for several indications other than bone tumors. Resection knee arthroplasty appears to be becoming more common, but patients requiring this type of surgery are often elderly and with high comorbidity. The aim of this study was to report in-hospital complications, readmissions, reoperations, and mortality after distal femoral resection knee arthroplasty for non-tumor indications.

METHODS

We retrospectively identified a consecutive cohort of 45 knees (45 patients) treated with distal femoral resection knee arthroplasty in a single institution between 2012 and 2021. Indications for surgery were failure of osteosynthesis (8), primary fracture treatment (2), periprosthetic fracture (22), and revision arthroplasty with severe bone loss (13). A major reoperation was defined as a major component exchange procedure or amputation. Mean follow-up was 3.9 years.

RESULTS

The mean age was 71.3 years (SD 12.3), and 64.4% were female; 8.9% were ASA I, 40% ASA II, and 51% ASA III. Median length of stay was 7 days (range 3-19) with no major in-hospital complications, but 55.6% (n = 25) required blood transfusion. The 90-day readmission rate was 17.8% (n = 8), of which 50% was prosthesis-related. Four patients (8.9%) underwent major reoperation due to infection (n = 2), mechanical failure (n = 1), or periprosthetic fracture (n = 1). The mortality rate was 0% ≤ 90 days and 2.2% ≤1 year.

CONCLUSIONS

Distal femoral resection knee arthroplasty in this fragile patient population appears to be a viable and safe option considering that it is a limp salvage procedure most cases.

Patients Who Undergo Early Aseptic Revision TKA Within 90 Days of Surgery Have a High Risk of Re-revision and Infection at 2 Years: A Large-database Study

BACKGROUND

Early aseptic revision within 90 days after primary TKA is a devastating complication. The causes, complications, and rerevision risks of aseptic revision TKA performed during this period are poorly described.

QUESTIONS/PURPOSES

(1) What is the likelihood of re-revision within 2 years after early aseptic TKA revision within 90 days compared with that of a control group of patients undergoing primary TKA? (2) What are the indications for early aseptic TKA revision within 90 days? (3) What are the differences in revision risk between different indications for early aseptic revision TKA?

METHODS

Patients who underwent unilateral aseptic revision TKA within 90 days of the index procedure were identified in a national insurance claims database (PearlDiver Technologies) using administrative codes. The exclusion criteria comprised revision for infection, history of bilateral TKA, and age younger than 18 years. The PearlDiver database was selected for its large and geographically diverse patient base and the availability of outpatient follow-up data that are unavailable in other databases focused on inpatient care. A total of 481 patients met criteria for early aseptic revision TKA, with 14% (67) loss to follow-up at 2 years. This final cohort of 414 patients was compared with a control group of patients who underwent primary TKA without revision within 90 days. For the control group, 137,661 patients underwent primary TKA without early revision, with 13% (18,138) loss to follow-up at 2 years. Among these patients, 414 controls were matched using a one-to-one propensity score method; no differences in age, gender, and Charlson comorbidity index score were observed between the groups. Indications for initial revision and 2-year re-revision were recorded. The Kaplan-Meier method was used to assess survival between the early revision and control groups.

RESULTS

Two-year survivorship free from additional revision surgery was lower in the early aseptic revision cohort compared with the control (78% [95% confidence interval 77% to 79%] versus 98% [95% CI 96% to 99%]; p < 0.001). Among early revisions, 10% (43 of 414) of the patients underwent re-revision for periprosthetic infection with an antibiotic spacer within 2 years. The reasons for early aseptic revision TKA were instability/dislocation (37% [153 of 414]), periprosthetic fracture (23% [96 of 414]), aseptic loosening (23% [95 of 414]), pain (11% [45 of 414]), and arthrofibrosis (6% [25 of 414]). Early revision for pain was associated with higher odds of re-revision than early revisions performed for other all other reasons (44% [20 of 45] versus 29% [100 of 344]; odds ratio 2.0 [95% CI 1.0 to 3.7]; p = 0.04).

CONCLUSION

Acute early aseptic revision TKA carries a high risk of re-revision at 2 years and a high risk of subsequent periprosthetic joint infection. Patients who undergo an early revision should be carefully counseled regarding the very high risk of repeat revision and discouraged from having early revision unless the indications are absolutely clear and compelling. Early aseptic revision for pain alone carries an unacceptably high risk of repeat revision and should not be performed. Adjunctive measures for infection prophylaxis should be strongly considered. Specific interventions to reduce surgical complications in this subset of patients have not been adequately studied; additional investigation of strategies to minimize the risk of reoperation or infection is warranted.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Fast-track revision knee arthroplasty

BACKGROUND

Limited data exist on fast-track protocols in relation to revision knee arthroplasty. Hence, the aim of this study was to report length of stay (LOS), risk of LOS > 5 days and readmission ≤ 90 days after revision knee arthroplasty in centers with a well-established fast-track protocol in both primary and revision surgery.

METHODS

An observational cohort study from the Centre for Fast-track Hip and Knee Replacement and the Danish Knee Arthroplasty Register. We included elective aseptic major component revision knee arthroplasties consecutively from 6 dedicated fast-track centers from 2010 to 2018.

RESULTS

1439 revision knee arthroplasties were analyzed, including 900 total revisions, 171 large partial revisions (revision of either femoral or tibia component) and 368 revisions of unicompartmental knee arthroplasty (UKA) to total knee arthroplasty (TKA). Mean age was 65 years (SD 10.9) and 66% were females. Mean LOS was 3.7 days (SD 3.9) in the study period, but decreased to 2.4 days (SD 1.3) in 2018. Risk factors for LOS > 5 days was ≥ 1 previous revision, use of walking aid, BMI > 35, ages < 50, 70-79 and ≥ 80 years, whereas revision of UKA to TKA and large partial revision were negatively associated. The 90-day readmission and mortality risk was 9.1% and 0.5%. Cardiac disease and use of walking aid were associated with increased risk of readmission ≤ 90 days.

CONCLUSION

Elective aseptic major component revision knee arthroplasty using similar fast-track protocols as in primary TKA is safe with short and decreasing LOS.

Length of stay, readmission, and mortality after primary surgery for pediatric spinal deformities: a 10-year nationwide cohort study

BACKGROUND CONTEXT

Extended length of stay (extLOS) and unplanned readmissions after first time pediatric spinal deformity surgery are a considerable challenge to both the patient and the health-care system. To our knowledge, only a limited number of nationwide studies reporting short-term comorbidity with complete follow-up exist.

PURPOSE

The purpose of this study was to identify the postoperative complications leading to extLOS, readmissions, and mortality within 90 days after surgery. Furthermore, to identify risk factors for readmission.

DESIGN

Retrospective national cohort study.

PATIENT SAMPLE

A nationwide registry study including all pediatric spinal deformity patients (≤21 years of age) undergoing primary surgery during 2006-2015 (n=1,310).

OUTCOME MEASURES

Reasons for extLOS and 90-day readmissions as well as mortality risk.

METHODS

Patients were identified by procedure and diagnosis codes in the Danish National Patient Registry (DNPR). Data on length of stay (LOS), readmissions, and mortality within 90 days were retrieved from the DNPR. Patients were categorized in six groups according to etiology. Reasons for extLOS and readmission were collected from medical records and discharge summaries.

RESULTS

For the 1,310 patients, the median LOS was 8 days (interquartile range 7-9). Etiologies were idiopathic deformity (53%), neuromuscular deformity (23%), congenital/structural deformity (9%), spondylolisthesis (7%), Scheuermann kyphosis (5%), and syndromic deformity (3%). A total of 274 (21%) patients had extLOS and the most common reason was pain/mobilization issues but with considerable variation between etiologies; Scheuermann kyphosis (91%), idiopathic (59%), syndromic (44%), spondylolisthesis (38%), and congenital (30%). Pulmonary complications were the primary reason for extLOS in the neuromuscular group (22%). The 90-day readmission rate was 6%; 67% of readmissions were medical, mainly infections unrelated to the surgical site (23%); 33% of readmissions were surgical and 14% of patients required revision surgery. Neuromuscular deformity, spondylolisthesis, Scheuermann kyphosis, and LOS >9 days were independent risk factors for readmission; odds ratio (OR) 4.4 (95% confidence interval: 2.2-9.1, p<.01), OR 3.0 (1.1-8.0, p=.03), OR 4.9 (1.7-13.6, p<.01), and OR 1.8 (1.0-3.1, p=.04), respectively. The 90-day mortality risk was 0.4%.

CONCLUSIONS

In this nationwide cohort, pain/mobilization issues are the most common reason for extLOS. The most common reason for readmission is infection unrelated to the surgical site. Readmission after pediatric spinal surgery is related to the etiology and increased focus on patients operated for neuromuscular deformity, spondylolisthesis and Scheuermann kyphosis is warranted.

Venous thromboembolism after fast-track elective revision hip and knee arthroplasty - A multicentre cohort study of 2814 unselected consecutive procedures

BACKGROUND

Venous thromboembolism (VTE) prophylaxis is much debated within total hip and knee arthroplasty (THA/TKA). Revision hip and knee arthroplasty (rTHA/rTKA) are more extensive procedures, but data on the risk of postoperative VTE is conflicting and there are no specific guidelines for thromboprophylaxis. Furthermore, data on rTHA/rTKA within a fast-track protocol is sparse. Thus, we aimed at evaluating the incidence and time course of VTE in unselected elective rTHA/rTKA within our established multicentre fast-track collaboration with in-hospital only thromboprophylaxis if length of stay (LOS) ≤ 5 days.

METHODS

We used an observational study design of unselected consecutive fast-track elective major component rTHA/rTKA from 6 dedicated fast-track centres between 2010 and 2018. We obtained information on revisions through Danish hip and knee arthroplasty registers and complete (>99%) 90 days follow-up through the Danish National Patient Registry in combination with chart review.

RESULTS

We included 2814 procedures with median LOS 3 days [2-5] and 21% had LOS >5 days. The 90-day incidence of VTE was 0.42% (n = 12), with 8 (0.28%) DVT and 4 (0.14%) PE, after median 14 days [IQR: 11-23] with the latest on day 31.

CONCLUSION

The 90-day incidence of VTE after elective fast-track rTHA and rTKA was about 0.4% which is comparable to the 90-day VTE incidence after primary fast-track THA, TKA and unicompartmental knee arthroplasty. Future investigations should focus on identification of high-risk patients while the surgical trauma per se may be less important.

Highlighting the Roles of Anemia and Aspirin in Predicting Ninety-Day Readmission Following Aseptic Revision Total Joint Arthroplasty

BACKGROUND

Revision total joint arthroplasties (TJAs) are associated with an increased rate of complications. To date, it is unclear what drives readmission after aseptic revision arthroplasty and what measures can be taken to possibly avoid them. The purpose of this study is to (1) determine the reasons for readmission after aseptic revision TJA and (2) identify patient-specific or postoperative risk factors through a multivariate analysis.

METHODS

A retrospective study examined 1503 cases of aseptic revision TJA between 2009 and 2016 at an urban tertiary care hospital. Eighty-seven cases (5.8%) of readmission within 90 days of index surgery were identified. Bivariate and multivariate analyses were performed to assess independent risk factors for readmission.

RESULTS

The reasons for readmission were infection (38%), wound complications (22%), and dislocation/instability of the prosthetic joint (13%). Only preoperative anemia was associated with an increased odds ratio (OR) of readmission (OR 1.82, 95% confidence interval [CI] 1.126-2.970, P = .015), whereas postoperative venous thromboembolism prophylaxis with aspirin (OR 0.58, 90% CI 0.340-0.974, P = .039) and discharge to an inpatient rehab facility (OR 0.22, 95% CI 0.051-0.950, P = .042) were associated with significantly lower odds of readmission.

CONCLUSION

Based on this single institutional study, addressing preoperative anemia and considering the implementation of aspirin for venous thromboembolism prophylaxis may be 2 targets to potentially reduce readmission after aseptic revision TJA.

Readmissions, Length of Stay, and Mortality After Primary Surgery for Adult Spinal Deformity: A 10-Year Danish Nationwide Cohort Study

STUDY DESIGN

Cohort study.

OBJECTIVE

To report outcome after primary surgery for adult spinal deformity (ASD), and assess risk factors for extended length of stay (extLOS) and readmission within 90 days.

SUMMARY OF BACKGROUND DATA

Complications after ASD surgery have been reported in 20% to 50% of patients. A few studies have focused on detailed information concerning postoperative morbidity.

METHODS

Patients >18 years undergoing primary instrumented surgery for ASD in Denmark in the period 2006 to 2016 were included. Patients were identified in the Danish National Patient Registry (DNPR) using procedure codes for instrumented spine surgery combined with diagnosis of spinal deformity. Information on length of stay (LOS), readmissions, and mortality were retrieved from the DNPR. Medical records were reviewed for causes of extLOS (LOS >10 days) and readmission within 90 days after surgery. Charlson Comorbidity Index (CCI) was calculated for all patients based on DNPR.

RESULTS

We included 892 patients. Median LOS was 8 days (interquartile range, IQR, 7-11). A total of 175 (28.0%) patients had extLOS; 81% because of "medically" related complications. Most common medically related reason (>50%) for extLOS was pain/mobilization difficulties. The 90-days readmission risk was 13.8%; 74.5% of readmissions were "medically" related, primarily opioid related side effects (18.2%), and pain/mobilization issues (15.2%); 25.5% of readmissions were "surgically" related and 16.7% of patients required revision surgery. Ninety-days mortality was 0.9%. Age groups 61 to 70 years, >70 years, CCI score 1 to 2 and CCI score ≥3 were associated with increased risk of extLOS (odds ratio, OR = 1.79, 2.01, 1.81, and 2.49, respectively). Age group >70 years and CCI score 1 to 2 were associated with increased risk of readmission (OR = 2.21 and 1.83).

CONCLUSION

Increasing age and comorbidity were associated with increased risk extLOS and readmission. Pain/mobilization difficulties were the most common postoperative complications. A future focus on early mobilization and pain management may improve outcome of ASD patients.

LEVEL OF EVIDENCE

3.

Enhanced recovery principles applied to revision hip and knee arthroplasty reduces length of stay and blood transfusion

INTRODUCTION

This is the first study reporting the application of Enhanced Recovery Principles (ERP) to revision arthroplasty.

METHOD

Retrospective series of 132 revision hip and knee replacements treated with ERP.

RESULTS

Infiltration was associated with reduced LOS in knees (6 vs 8.5 days), lower PCA usage and incidence of transfusion in knees (2 vs 3 days) and hips (1 vs 6 days). Revisions for infection had a longer LOS (5.4 vs 11.5 days p = 0.001), a greater use of PCA and a higher incidence of transfusion (5 vs 0) in both knees and hips.

DISCUSSION

The application of ERPs to revision arthroplasty is safe. Infiltration appears to be an important factor in improving outcome measures.

Revision of infected knee arthroplasties in Denmark

Background and purpose - The surgical treatment of periprosthetic knee infection is generally either a partial revision procedure (open debridement and exchange of the tibial insert) or a 2-stage exchange arthroplasty procedure. We describe the failure rates of these procedures on a nationwide basis. Patients and methods - 105 partial revisions (100 patients) and 215 potential 2-stage revision procedures (205 patients) performed due to infection from July 1, 2011 to June 30, 2013 were identified from the Danish Knee Arthroplasty Register (DKR). Failure was defined as surgically related death ≤ 90 days postoperatively, re-revision due to infection, or not reaching the second stage for a planned 2-stage procedure within a median follow-up period of 3.2 (2.2-4.2) years. Results - The failure rate of the partial revisions was 43%. 71 of the partial revisions (67%) were revisions of a primary prosthesis with a re-revision rate due to infection of 34%, as compared to 55% in revisions of a revision prosthesis (p = 0.05). The failure rate of the 2-stage revisions was 30%. Median time interval between stages was 84 (9-597) days. 117 (54%) of the 2-stage revisions were revisions of a primary prosthesis with a re-revision rate due to infection of 21%, as compared to 29% in revisions of a previously revised prosthesis (p = 0.1). Overall postoperative mortality was 0.6% in high-volume centers (> 30 procedures within 2 years) as opposed to 7% in the remaining centers (p = 0.003). Interpretation - The failure rates of 43% after the partial revision procedures and 30% after the 2-stage revisions in combination with the higher mortality outside high-volume centers call for centralization and reconsideration of surgical strategies.