Association Between Digitally Provided Education and 90-Day Return to Sexual Activity Following Total Knee Arthroplasty: A Randomized Controlled Trial

BACKGROUND

Contemporary total knee arthroplasty patients have increased expectations of returning to predisease function, including sexual activity (SA). The purpose of this study was to determine whether patients using a digital care management platform (DCMP) were more likely to have a higher rate and frequency of return to SA.

METHODS

We conducted an exploratory analysis of a prospective, multicenter, randomized controlled trial that enrolled patients undergoing total knee arthroplasty. A total of 304 patients were randomized to a DCMP (n = 119) providing preoperative and postoperative education regarding return to SA or standard postoperative care (control group; n = 185). Return to SA, assessed via questionnaire, patient-reported outcome measures, Timed Up and Go test, single leg stance, active range of motion and need for manipulation under anesthesia were assessed at 90 days postoperatively.

RESULTS

More patients in the DCMP group returned to SA compared to control at 90 days (58.4 versus 39.6%, P = .018); however, the control group resumed SA sooner (33.1 versus 42.0 days, P = .023). Patients who returned to SA were younger (61.6 versus 65.9 year), more often men (56 versus 35%) (P < .001), higher performing on the Timed Up and Go and single leg stance tests (P < .001), and had greater active range of motion (P = .007). There were no differences in patient-reported outcome measures or need for manipulation under anesthesia between patients that returned to SA and those who did not.

CONCLUSIONS

More patients using a DCMP resumed SA at 90 days; however, patients in the control group returned to SA sooner. Those who returned to SA were younger, possessed greater physical function, and were more often men.

Joint line position change in primary total knee arthroplasty: a radiographic analysis comparing conventional and robotic techniques

PURPOSE

Joint line (JL) position change in total knee arthroplasty (TKA) may alter knee biomechanics and impact function. The purpose of this study was to compare the change in JL position between robotic-assisted TKA (RA-TKA) and conventional TKA (C-TKA).

METHODS

A retrospective, radiographic analysis was conducted of patients who underwent RA-TKA and C-TKA to compare JL position change. JL position was measured in consecutive RA-TKAs and C-TKAs performed by four fellowship-trained arthroplasty surgeons. Statistical analysis was done utilizing t-tests and Mann Whitney U tests, with statistical significance being defined as a p value < 0.05.

RESULTS

Six hundred total RA-TKAs and 400 total C-TKAs were included in the analysis. There were no significant differences in patient baseline characteristics such as body mass index, range of motion, and tibiofemoral coronal alignment. RA-TKAs were associated with an average of 0.04 (2.2) mm JL position change, and C-TKAs were associated with an average 0.5 (3.2) mm JL position change (p = 0.030). There were inter-surgeon differences when comparing the change in JL position for RA-TKAs and C-TKAs between the four participating surgeons.

CONCLUSION

RA-TKA leads to better preservation of the JL position than C-TKA, and this seems to be dependent on the arthroplasty surgeon's preferences and techniques during TKA. Whether this statistically significant difference is clinically relevant needs to be further investigated.

Debridement, Antibiotics, and Implant Retention in Unicompartmental Knee Arthroplasty Infection

BACKGROUND

This multicenter study sought to further investigate the method and outcome of debridement, antibiotics, and implant retention (DAIR) for the management of unicompartmental knee periprosthetic joint infection (PJI).

METHODS

This retrospective study was performed on 52 patients who underwent DAIR for PJI of a unicompartmental knee arthroplasty (UKA) across 4 academic medical centers, all performed by fellowship-trained arthroplasty surgeons. Patient demographics, American Society of Anesthesiologists score, infecting organism, operative data, antibiotic data, and success in infection control at 1 year were collected.

RESULTS

The average time from index surgery to diagnosis of PJI was 11.1 weeks (range, 1.4 to 48). There was no correlation between time of diagnosis and success at 1 year (R = 0.09, P = .46). There was an association between surgical synovectomy and the eradication of infection (R = 0.28, P = .04). Overall, there was an 80.8% (42 of 52) infection-controlled success rate at 1 year from the DAIR procedure. All DAIR failures went on to require another procedure, either 1-stage (2 of 10) or 2-stage (8 of 10) revision to total knee arthroplasty (TKA). Of the DAIR successes, 6 (14.3%) went on to require conversion to TKA for progression of arthritis within 5 years.

CONCLUSIONS

This study demonstrates that DAIR is a safe and moderately effective procedure in the setting of acute PJI of UKA across institutions, with a success rate consistent with DAIR for TKA. The data suggest that a wide exposure and thorough synovectomy be incorporated during the DAIR UKA to improve the likelihood of successful eradication of PJI at the 1-year mark.

LEVEL OF EVIDENCE

Level III.

The Efficacy of Preoperative Video-Based Opioid Counseling on Postoperative Opioid Consumption After Total Knee Arthroplasty: A Prospective Randomized Controlled Trial

BACKGROUND

There are myriad strategies to reduce opioid consumption after total knee arthroplasty (TKA). Recent studies have suggested that preoperative counseling may reduce opioid use after a variety of orthopedic procedures. The purpose of this study was to investigate whether preoperative video-based patient education regarding opioid use and abuse reduces opioid consumption after TKA.

METHODS

In this prospective randomized controlled trial, patients were randomized before TKA to either receive preoperative video-based counseling or not. Counseling involved a pretaped 5-minute video that educated patients on statistics regarding the "opioid epidemic" and discussed safe use and alternatives to opioids after TKA. There were no significant differences in baseline patient demographics between groups. All patients received a similar multimodal perioperative pain management protocol and completed a daily diary for 2 weeks postoperatively. Diary records measured pain levels using a visual analog score, opioid consumption, side effects experienced, and patient opinion and satisfaction regarding their pain control.

RESULTS

Patients in the counseling group consumed significantly less morphine milligram equivalents on postoperative days 0 to 3 (78.8 versus 106.1, P = .020) and in week one postoperatively (129.9 versus 180.7, P = .028), with a trend of less consumption over 2 weeks postoperatively (186.9 versus 239.1, P = .194). There were no significant differences in the number of patients requiring refills, side effects, or daily pain levels between the 2 groups.

CONCLUSIONS

This study found significantly decreased opioid consumption within the first week after TKA in patients who received preoperative video counseling.

Return to Sport After Unicompartmental Knee Arthroplasty and Patello-Femoral Arthroplasty

BACKGROUND

Data on sports/physical activity participation following unicompartmental knee arthroplasty (UKA) and patello-femoral arthroplasty (PFA) is variable and limited. The purpose of this study was to assess participations, outcomes, and limitations in sports following UKA and PFA.

METHODS

Patients who underwent UKA and PFA at a single institution from 2015 to 2020 were surveyed on sports participation before and after surgery. Data was correlated with perioperative patient characteristics and outcome scores. Among 776 patients surveyed, 356 (50%) patients responded. Of respondents, 296 (83.1%) underwent UKA, 44 (12.6%) underwent PFA, and 16 (4.5%) underwent both UKA/PFA.

RESULTS

Activity participation rates were 86.5, 77.3, and 87.5% five years prior, and 70.9, 61.4, and 75% at one year prior to UKA, PFA, and UKA/PFA, respectively. Return to sports rates were 81.6, 64.7, and 62.3% at mean 4.6 years postoperatively, respectively. The most common activities were recreational walking, swimming, cycling, and golf. Patients returned to a similar participation level for low-impact activities, whereas participation decreased for intermediate- and high-impact activities. Patients participating in activities had higher postoperative Knee Injury and Osteoarthritis Outcome Score Joint Replacement (P < .001), 12-Item Short Form Physical Component Score (P = .045) and Mental Component Score (P = .012). Activity restrictions were reported among 25, 36.4, and 25% of UKA, PFA, and UKA/PFA patients, respectively, and were more commonly self-imposed than surgeon-directed.

CONCLUSIONS

Though UKA patients' postoperative sports participation may improve compared to one year preoperatively, participation for patients surgically treated for isolated osteoarthritis is decreased compared to 5 years preoperatively and varies among patient subsets.

Interpreting the Current Literature on Outcomes of Robotic-Assisted Versus Conventional Total Knee Arthroplasty Using Fragility Analysis: A Systematic Review and Cross-Sectional Study of Randomized Controlled Trials

BACKGROUND

Fragility analysis is a method of further characterizing outcomes in terms of the stability of statistical findings. This study assesses the statistical fragility of recent randomized controlled trials (RCTs) evaluating robotic-assisted versus conventional total knee arthroplasty (RA-TKA versus C-TKA).

METHODS

We queried PubMed for RCTs comparing alignment, function, and outcomes between RA-TKA and C-TKA. Fragility index (FI) and reverse fragility index (RFI) (collectively, "FI") were calculated for dichotomous outcomes as the number of outcome reversals needed to change statistical significance. Fragility quotient (FQ) was calculated by dividing the FI by the sample size for that outcome event. Median FI and FQ were calculated for all outcomes collectively as well as for each individual outcome. Subanalyses were performed to assess FI and FQ based on outcome event type and statistical significance, as well as study loss to follow-up and year of publication.

RESULTS

The overall median FI was 3.0 (interquartile range, [IQR] 1.0 to 6.3) and the median reverse fragility index was 3.0 (IQR 2.0 to 4.0). The overall median FQ was 0.027 (IQR 0.012 to 0.050). Loss to follow-up was greater than FI for 23 of the 38 outcomes assessed.

CONCLUSIONS

A small number of alternative outcomes is often enough to reverse the statistical significance of findings in RCTs evaluating dichotomous outcomes in RA-TKA versus C-TKA. We recommend reporting FI and FQ alongside P values to improve the interpretability of RCT results.

Completion of Patient-Reported Outcome Measures Improved With Use of a Mobile Application in Arthroplasty Patients: Results From a Randomized Controlled Trial

BACKGROUND

The collection of patient-reported outcome measures (PROMs) has historically been reported as costly and time-consuming, with low compliance rates that may impact reimbursement. Little research has reported the effects of mobile applications to support PROMs collection following arthroplasty.

METHODS

Secondary analysis of data from a multicenter randomized controlled trial was performed. Patients undergoing knee and hip arthroplasty were randomized to utilize a smartphone-based care management platform (app) for self-directed rehabilitation and completed joint-specific PROMs (Hip Dysfunction and Osteoarthritis Outcome Score, Joint Replacement or Knee Injury and Osteoarthritis Score, Joint Replacement) via the application at prescribed intervals or on paper during clinic visits. Control patients received practice standard of care, and completed PROMs via emailed hyperlink or during clinic visits following lower limb arthroplasty. Overall, 455 patients underwent knee arthroplasty procedures (245 control, 210 app group) and 380 underwent total hip arthroplasty (206 control, 174 app group). Compliance with expected PROMs completion was calculated through one year postoperatively.

RESULTS

Compliance was higher in the app group preoperatively in both knee (98.1 versus 86.9%, P < .0001) and hip cohorts (96.0 versus 88.4%, P = .008), and postoperatively, including at one year (knees, 72.2 versus 53.7%, P < .0001; hips, 71.1 versus 49.2%, P < .0001). On log-binomial regressions, intervention arm was the strongest predictor of completion of all PROMs, where app users undergoing knee (Relative Risk 2.039, 95% confidence interval (CI) 1.595 to 2.607, P < .000) and hip arthroplasty (2.268 95% CI 1.742 to 2.953, P < .0001) were more likely to be compliant at all timepoints. The majority of patients in the app group, including those over 65 years of age, completed PROMs using the application as opposed to paper methods.

CONCLUSIONS

A smartphone mobile application that engages patients during recovery after knee and hip joint arthroplasty improved compliance with completion of preoperative and postoperative PROMs compared to other electronic and paper methods.

Robotic-Assisted Total Knee Arthroplasty Has Similar Rates of Prosthetic Noise Generation as Conventional Total Knee Arthroplasty

Background

Noise has been reported to occur with relatively high frequency after conventional total knee arthroplasty (C-TKA), and this may impact the incidence of patient satisfaction and function. The purpose of this study was to compare the rate of patient-reported prosthetic noise generation after robotically-assisted TKA (RA-TKA) and C-TKA.

Methods

A retrospective study was conducted of unilateral primary RA-TKAs and C-TKAs performed between 2018 and 2021. Patients completed a survey consisting of 4 Likert scale questions related to prosthetic noise generation and Knee Injury and Osteoarthritis Score Joint Replacement and Forgotten Joint Score were assessed prospectively preoperatively and at a minimum of 1-year of clinical follow-up. Statistical analysis was done utilizing T-tests and chi-square tests, with statistical significance defined as a P-value < .05.

Results

One hundred sixty-two RA-TKAs and 320 C-TKAs with similar baseline characteristics and functions were included. There were no significant differences in hearing or feeling grinding, popping, clicking, or clunking (40.7% vs 38.1%; P = .647) between groups. Most RA-TKAs and C-TKAs were not dissatisfied regarding noise generation (70.4% vs 73.1%; P = .596). In both cohorts, patients who reported noise generation had lower average Forgotten Joint Scores (45.5 vs 66.1; P < .001) and lower postoperative Knee Injury and Osteoarthritis Score Joint Replacement scores (72.0 vs 81.4; P < .001) than those who did not experience noise generation.

Conclusions

While RA-TKA may facilitate soft tissue balancing, there were no differences in prosthetic noise generation between RA-TKA and C-TKA. However, those who experience implant-generated noise have lower functional outcome scores.

Robotic-Assisted Total Knee Arthroplasty: What are Patients' Perspectives, Understanding and Expectations?

BACKGROUND

The rate of using robotic-assisted total knee arthroplasty (RA-TKA) has increased markedly. Understanding how patients view the role of robotics during total knee arthroplasty (TKA) informs shared decision making and facilitate efforts to appropriately educate patients regarding the risks and benefits of robotic assistance.

METHODS

A self-administered questionnaire was completed by 440 potential TKA patients at the time of their surgery scheduling. Participants answered 25 questions regarding RA-TKA, socioeconomic factors, and their willingness to pay (WTP) for RA-TKA. Logistic regressions were used to determine if population characteristics and surgeon preferences influenced the patients' perceptions of RA-TKA.

RESULTS

There were 39.7% of respondents who said that they had no knowledge regarding RA-TKA. Only 40.7% of participants had expressed a desire for RA-TKA to be used. There were 8.7% who were WTP extra for the use of RA-TKA. Participants believed that the main 3 benefits of RA-TKA compared to conventional methods were: more accurate implant placement (56.2%); better results (49.0%); and faster recovery (32.1%). The main 3 patient concerns were harm from malfunction (55.2%), reduced surgeon role in the procedure (48.1%), and lack of supportive research (28.3%). Surgeon preference of RA-TKA was associated with patient's willingness to have RA-TKA (odds ratio 4.60, confidence interval 2.98-7.81, P < .001), and with WTP extra for RA-TKA (odds ratio 2.05, confidence interval: 1.01-4.26, P = .049).

CONCLUSION

Patient knowledge regarding RA-TKA is limited. Nonpeer-reviewed online information may make prospective TKA candidates vulnerable to misinformation and aggressive advertising. The challenge for orthopaedic surgeons is to re-establish control and reliably educate patients about the proven advantages and disadvantages of this emerging technology.

Unicompartmental Knee Arthroplasty Is Cost-Effective in an Outpatient Setting

INTRODUCTION

Increasingly, unicompartmental knee arthroplasty (UKA) is being performed on an outpatient basis, with the growing utilization of ambulatory surgery centers (ASCs). The purpose of this study was to compare the costs of UKAs performed in an ASC to UKAs done in a hospital, either on an outpatient or inpatient basis.

METHODS

This study involved three matched groups, each with 50 consecutive patients, undergoing UKA either on an outpatient basis in an ASC or a community hospital, or who were admitted overnight to the same community hospital. Identical perioperative analgesic regimens and care protocols were used in each group. The primary outcomes evaluated included direct facility costs. Secondary outcomes were postoperative complications and readmissions.

RESULTS

Average age, gender ratio, and comorbidities were similar in all three cohorts. Only two patients in the study experienced complications and these were without secondary adverse consequences. Mean costs were substantially reduced when UKAs were performed in an ASC ($9,025) compared to a community hospital on either an outpatient ($12,032) or inpatient basis ($14,542).

CONCLUSION

UKA can be safely performed in the outpatient setting, in appropriately selected patients, at substantial cost savings, particularly when performed in an ASC.

Manipulation Under Anesthesia is Safe After Cementless Total Knee Arthroplasty: A Multicenter Study

BACKGROUND

Cementless total knee arthroplasty (TKA) is thought to facilitate durable, biological fixation between the bone and implant. However, the 4-12 weeks required for osseointegration coincides with the optimal timeframe to perform a manipulation under anesthesia (MUA) if a patient develops postoperative stiffness. This study aims to determine the impact of early MUA on cementless fixation by comparing functional outcomes and survivorship of cementless and cemented TKAs.

METHODS

A consecutive series of patients who underwent MUA for postoperative stiffness within 90 days of primary, unilateral TKA at 2 academic institutions between 2014 and 2018 were identified. Cases involving extensive hardware removal were excluded. Cementless TKAs undergoing MUA (n = 100) were propensity matched 1:1 to cemented TKAs undergoing MUA (n = 100) using age, gender, body mass index, and year of surgery. Both groups had comparable baseline Knee Injury and Osteoarthritis Outcome Scores (KOOS), Short Form (SF)-12 Physical, and SF-12 Mental scores. MUA-related complications as well as postoperative KOOS and SF-12 scores were compared.

RESULTS

MUA-related complications were equivalently low in both groups (P = .324), with only 1 patella component dissociation in the cementless group. No tibial or femoral components acutely loosened in the perioperative period. Postoperative KOOS (P = .101) and SF-12 Mental scores (P = .380) were similar between groups. Six-year survivorship free from any revision after MUA was 98.0% in both groups (P = 1.000).

CONCLUSION

Early postoperative MUA after cementless TKA was not associated with increased MUA-related complications or worse patient-reported outcomes compared to cemented TKA. Short-term survivorship was also comparable, suggesting high durability of the bone-implant interface.

Surgeons Experience More Physiologic Stress and Strain During Revision Than Primary Total Joint Arthroplasty

BACKGROUND

Revision total knee arthroplasty (rTKA) and total hip arthroplasty (rTHA) procedures are more complex than primary TKA and THA, but their physiologic burden to the surgeon has not been quantified. While rTKA and rTHA have longer operative times, it is unknown whether differences exist in stress and strain compared to primary TKA and primary THA. The study was conducted to elicit whether differences exist in surgeon physiological response while performing rTKA and rTKA compared to primary TKA and primary THA.

METHODS

We evaluated a prospective cohort study of 70 consecutive cases (23 primary TKAs, 12 primary THAs, 16 rTKAs, and 19 rTHAs). Two high-volume fellowship-trained arthroplasty surgeons wore a smart vest that recorded cardiorespiratory data while performing primary THA, primary TKA, rTHA, and rTKA. Heart rate (beats/minute), stress index (correlates with sympathetic activation), respiratory rate (respirations/minute), minute ventilation (L/min), and energy expenditure (Calories) were collected for every case, along with patient body mass index (kilograms/meter²) and working operative time (minutes). T-tests were used to assess for differences between the two groups.

RESULTS

Compared to primary TKA, performing rTKAs had a significantly higher surgeon stress index (17 versus 15; P = .035), heart rate (104 versus 99; P = .007), energy expenditure per case (409 versus 297; P = .002), and a significantly lower heart rate variability (11 versus 12; P = .006). Compared to primary THA, performing rTHA had a significantly higher energy expenditure per case (431 versus 307; P = .007) and trended towards having a higher surgeon stress index (16 versus 14; P = .272) and a lower heart rate variability (11 versus 12; P = .185), although it did not reach statistical significance.

CONCLUSION

Surgeons experience higher physiological stress and strain when performing rTKA and rTHA compared to primary TKA and primary THA. This study provides objective data on what many surgeons feel and should promote further research on the specific stress and strain felt by surgeons who perform revision arthroplasty procedures.

Pin-Related Complications in Computer Navigated and Robotic-Assisted Knee Arthroplasty: A Systematic Review

BACKGROUND

Computer-assisted navigation (CAN) and robotic-assisted (RA) knee arthroplasty procedures carry unique risks of tracking pin-related complications. This systematic review aimed to quantitatively assess the incidence, timing, treatment, and clinical outcomes of all tracking pin-related complications following CAN and RA knee arthroplasty.

METHODS

A systematic review was performed using PubMed, Cochrane Central and Scopus databases. All clinical studies that documented pin-related complications associated with the use of CAN or RA for total or partial knee arthroplasty were included. Descriptive statistics were analyzed when data were available.

RESULTS

Thirty-six studies were included: 18 case reports (25 cases) and 18 randomized controlled trials, cohort studies and case series i.e., non-case reports (7,336 cases). The most common pin-related complication among case reports was fracture (n = 22; 81%). The overall rate of pin-related complications among non-case reports was 1.4%. The intraoperative and postoperative complication with the highest incidence were pin dislodgement (0.6%) and superficial pin site infections (0.6%), respectively. Most postoperative complications were related to the tibial site (69%). All complications were effectively treated and resolved at follow-up.

CONCLUSION

Pin-related complications following CAN and RA knee arthroplasty are relatively uncommon. While pin loosening, superficial infections and fractures have been most commonly documented, other complications such as vascular injury, myositis ossificans, and osteomyelitis can also occur. The potential for pin-related complications should be considered by arthroplasty surgeons, especially during early stages of adoption. Further studies investigating patient risk factors for pin-related complications are warranted.

Topical Cannabidiol (CBD) After Total Knee Arthroplasty Does Not Decrease Pain or Opioid Use: A Prospective Randomized Double-Blinded Placebo-Controlled Trial

BACKGROUND

Multimodal analgesia has become the standard of care for pain management following total knee arthroplasty (TKA). Cannabidiol (CBD) is increasingly utilized in the postoperative period. The purpose of this study was to analyze the analgesic benefits of topical CBD following primary TKA.

METHODS

In this randomized double-blinded placebo-controlled trial, 80 patients undergoing primary unilateral TKA applied topical CBD (CBD; n = 19), essential oil (EO; n = 21), CBD and essential oil (CBD + EO; n = 21), or placebo (PLA; n = 19) thrice daily around the knee for two weeks postoperatively. This supplemented a standardized multimodal analgesic protocol. Outcomes included visual analog scale (VAS) pain and numeric rating scale (NRS) sleep scores (collected on postoperative day [POD] 0, 1, 2, 7, 14, 42), and cumulative postoperative opioid use (42 days).

RESULTS

Demographic characteristics were similar among the four cohorts. Preoperative VAS and NRS scores were similar among groups. The CBD cohort had a higher mean VAS pain score on POD 2 compared to the EO cohort (CBD: 69.9 ± 19.3 versus. EO: 51.0 ± 18.2; P = .013). No statistically significant differences existed for VAS scores at other times, and no statistically significant differences were observed for postoperative NRS sleep scores or postoperative opioid use at any time point.

CONCLUSION

Utilization of topical CBD in supplement to multimodal analgesia did not reduce pain or opioid consumption, or improve sleep scores following TKA. These results suggest that the local effects of topical CBD are not beneficial for providing additional pain relief after TKA.

The Paradox of Patient-Reported Outcome Measures: Should We Prioritize "Feeling Better" or "Feeling Good" After Total Knee Arthroplasty?

BACKGROUND

The use of preoperative patient-reported outcome measure (PROM) thresholds for patient selection in arthroplasty care has been questioned recently. This study aimed to identify factors affecting achievement of the minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) after total knee arthroplasty (TKA) and determine the overlap between the two outcomes.

METHODS

We identified 1,239 primary, unilateral TKAs performed at a single institution in 2015-2019. PROMs including the Knee injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS-JR) and 12-item Short Form Health Survey (SF-12) were collected preoperatively and 1-year postoperatively. The likelihood of attaining PASS as per attainment of MCID was assessed. A multivariable regression was used to identify predictors of MCID and PASS.

RESULTS

In total, 71.3% achieved MCID and 75.5% achieved PASS for KOOS-JR. Only 7.7% achieved MCID but not PASS, whereas almost twice this number did not achieve MCID but did achieve PASS (11.9%). Poorer preoperative KOOS-JR (OR 0.925), better SF-12 physical (OR 1.025), and mental (OR 1.027) were associated with MCID attainment. In contrast, better preoperative KOOS-JR (OR 1.030) and SF-12 mental (OR 1.025) were associated with PASS attainment. Age, gender, race, ethnicity, body mass index, Charlson index, American Society of Anesthesiologists classification, and smoking status were not significant predictors.

CONCLUSION

Preoperative PROMs were associated with achieving MCID and PASS after TKA, albeit some positively and some negatively. In the era of value-based care, clinicians should not only strive to help patients "feel better" but also ensure that patients "feel good" after surgery. This study does not support the use of PROMs in prioritizing access to care.

Improved accuracy and reproducibility of a novel CT-free robotic surgical assistant for medial unicompartmental knee arthroplasty compared to conventional instrumentation: a cadaveric study

PURPOSE

Alignment errors in medial unicompartmental knee arthroplasty (UKA) predispose to premature implant loosening and polyethylene wear. The purpose of this study was to determine whether a novel CT-free robotic surgical assistant improves the accuracy and reproducibility of bone resections in UKA compared to conventional manual instrumentation.

METHODS

Sixty matched cadaveric limbs received medial UKA with either the ROSA^® Partial Knee System or conventional instrumentation. Fifteen board-certified orthopaedic surgeons with no prior experience with this robotic application performed the procedures with the same implant system. Bone resection angles in the coronal, sagittal and transverse planes were determined using optical navigation while resection depth was obtained using calliper measurements. Group comparison was performed using Student's t test (mean absolute error), F test (variance) and Fisher's exact test (% within a value), with significance at p < 0.05.

RESULTS

Compared to conventional instrumentation, the accuracy of bone resections with CT-free robotic assistance was significantly improved for all bone resection parameters (p < 0.05), other than distal femoral resection depth, which did not differ significantly. Moreover, the variance was significantly lower (i.e. fewer chances of outliers) for five of seven parameters in the robotic group (p < 0.05). All values in the robotic group had a higher percentage of cases within 2° and 3° of the intraoperative plan. No re-cuts of the proximal tibia were required in the robotic group compared with 40% of cases in the conventional group.

CONCLUSION

The ROSA^® Partial Knee System was significantly more accurate, with fewer outliers, compared to conventional instrumentation. The data reported in our current study are comparable to other semiautonomous robotic devices and support the use of this robotic technology for medial UKA.

LEVEL OF EVIDENCE

Cadaveric study, Level V.

Staged BiCompartmental Knee Arthroplasty has Greater Functional Improvement, but Equivalent Midterm Survivorship, as Revision TKA for Progressive Osteoarthritis After Partial Knee Arthroplasty

BACKGROUND

Progressive arthritis in the unresurfaced compartments of the knee is one failure mode after partial knee arthroplasty (PKA). While progressive arthritis after PKA is typically treated with revision to TKA (rTKA), staged bicompartmental knee arthroplasty (sBiKA) -the addition of another PKA - is an alternative. This study compared outcomes of sBiKA and rTKA for progressive arthritis after PKA.

METHODS

A retrospective comparative study of non-consecutive cases at four institutions were performed in patients with an intact PKA, without loosening or wear, who underwent sBiKA (n = 27) or rTKA (n = 30), for progressive osteoarthritis. Outcomes studied were new Knee Society Function and Objective Scores (KSSF, KSSO), KOOS, Jr., ROM, operative times, length of stay, complication rates and the need for reoperations.

RESULTS

Mean time to conversion was 7.4 ± 6 years for sBiKA and 9.7 ± 8 for rTKA, P = .178. Patient demographics and pre-operative outcomes were similar among cohorts. At an average of 5.7 ± 3 (sBiKA) and 3.2 ± 2 years (rTKA), KOOS, Jr. significantly improved, P < .001, by an equivalent amount. Post-operative KSSO and KSSF were significantly higher in the sBiKA cohort, respectively, (90.4 ± 10 vs 72.1 ± 20, P < .001) and (80.3 ± 18 vs 67.1 ± 19, P = .011). sBiKA patients had significantly greater improvement in KSSO (30.7 ± 33 vs 5.2 ± 18, P = .003). One sBiKA patient underwent reoperation for continued pain.

CONCLUSION

SBiKA has equivalent survivorship, but greater improvement in functional outcomes as rTKA at short to midterm follow-up. Given the shorter operative times and length of stay, sBiKA is a safe and cost-effective alternative to rTKA for progressive osteoarthritis following PKA. Nevertheless, further follow-up is necessary to determine whether sBiKA is a durable option.

Robotic-Assisted Versus Manual Unicompartmental Knee Arthroplasty: A Time-Driven Activity-Based Cost Analysis

BACKGROUND

The cost-effectiveness of robotic-assisted unicompartmental knee arthroplasty (RA-UKA) remains unclear. Time-driven activity-based costing (TDABC) has been shown to accurately reflect true resource utilization. This study aimed to compare true facility costs between RA-UKA and conventional UKA.

METHODS

We identified 265 consecutive UKAs (133 RA, 132 conventional) performed at a specialty hospital in 2016-2020. Itemized facility costs were calculated using TDABC. Separate analyses including and excluding implant costs were performed. Multiple regression was performed to determine the independent effect of robotic assistance on facility costs.

RESULTS

Due to longer operative time, RA-UKA patients had higher personnel costs and total facility costs ($2,270 vs $1,854, P < .001). Controlling for demographics and comorbidities, robotic assistance was associated with an increase in personnel costs of $399.25 (95% confidence interval [CI] $343.75-$454.74, P < .001), reduction in supply costs of $55.03 (95% CI $0.56-$109.50, P = .048), and increase in total facility costs of $344.27 (95% CI $265.24-$423.31, P < .001) per case. However, after factoring in implant costs, robotic assistance was associated with a reduction in total facility costs of $235.87 (95% CI $40.88-$430.85, P < .001) per case.

CONCLUSION

Using TDABC, overall facility costs were lower in RA-UKA despite a longer operative time. To facilitate wider adoption of this technology, implant manufacturers may negotiate lower implant costs based on volume commitments when robotic assistance is used. These supply cost savings appear to offset a portion of the increased costs. Nonetheless, further research is needed to determine if RA-UKA can improve clinical outcomes and create value in arthroplasty.

Total Knee Arthroplasty With Robotic Surgical Assistance Results in Less Physician Stress and Strain Than Conventional Methods

BACKGROUND

Poor surgical ergonomics and physiological stress have been shown to impair surgical performance and cause injuries. The prevalence of musculoskeletal pain among arthroplasty surgeons is inordinately high. This study compared surgeon stress and strain during robotic-assisted total knee arthroplasty (rTKA) and conventional TKA (cTKA).

METHODS

Continuous cardiorespiratory and ergonomic data of a single surgeon were measured during 40 consecutive unilateral TKAs (20 rTKAs, 20 cTKAs) using a smart garment and wearable sensors. Heart rate (HR), HR variability, respiratory rate, minute ventilation, and calorie expenditure were used as surrogate measures for physiological stress. Intraoperative ergonomics were assessed by measuring cervical and lumbar flexion, extension and rotation, and shoulder abduction/adduction.

RESULTS

Mean operative time was longer for rTKA (48.2 ± 9 vs 31.8 ± 7 min, P < .001). Calories expended per minute was lower for rTKA (2.53 vs 3.50, P < .001). Total calorie expenditure in rTKA cases 11-20 was significantly lower than the first 10 (107.1 ± 27 vs 137.6 ± 24, P = .015), and lower than cTKA (112.3 ± 37). Mean HR was lower for rTKA (81.5 ± 4 vs 90.1 ± 5, P < .001). Minute ventilation was also lower for rTKA (14.9 ± 1 vs 17.0 ± 1.0 L/min, P < .001). Mean lumbar flexion as well as the percentage of time spent in a demanding flexion position >20° were significantly lower during rTKA (P < .001).

CONCLUSION

rTKA resulted in less surgeon physiologic stress, energy expenditure per minute, and postural strain compared to cTKA. Robotic assistance may help to increase surgical efficiency and reduce physician workload, but further studies are needed to determine whether these benefits will reduce musculoskeletal pain and injury among surgeons.

Surgeons Experience Greater Cardiorespiratory Strain and Stress During Total Hip Arthroplasty Than Total Knee Arthroplasty

BACKGROUND

Total hip arthroplasty (THA) and total knee arthroplasty (TKA) are physically demanding, with a high prevalence of work-related injuries among arthroplasty surgeons. It is unknown whether there are differences in cardiorespiratory output for surgeons while performing THA and TKA. The objective of this study is to characterize whether differences in surgeon physiological response exist while performing primary THA vs TKA.

METHODS

This is a prospective cohort study including 3 high-volume, fellowship-trained arthroplasty surgeons who wore a smart garment that recorded cardiorespiratory data on operative days during which they were performing primary conventional TKA and THA. Variables collected included patient body mass index (BMI), operative time (minutes), heart rate, heart rate variability, respiratory rate, minute ventilation, and energy expenditure (calories).

RESULTS

Seventy-six consecutive cases (49 THAs and 27 TKAs) were studied. Patient BMI was similar between the 2 cohorts (P > .05), while operative time was significantly longer in TKAs (60.4 ± 12.0 vs 53.6 ± 11.8; P = .029). During THA, surgeons had a significantly higher heart rate (95.7 ± 9.1 vs 90.2 ± 8.9; P = .012), energy expenditure per minute (4.6 ± 1.23 vs 3.8 ± 1.2; P = .007), and minute ventilation (19.0 ± 3.0 vs 15.5 ± 3.3; P < .001) compared to TKA.

CONCLUSION

Surgeons experience significantly higher physiological strain and stress while performing THA. While scheduling THAs and TKAs, surgeons should consider the higher physical demand associated with THAs and ensure adequate personal preparation and sequence of cases.

What Are the All-Cause Survivorship Rates and Functional Outcomes in Patients Younger Than 55 Years Undergoing Primary Knee Arthroplasty? A Systematic Review

BACKGROUND

Approximately one-fourth of TKAs will be performed in patients 55 years or younger within the next decade. Postoperative outcomes for younger patients who had a knee arthroplasty were systematically reviewed in 2011; however, numerous studies evaluating young patients who had both a TKA and unicompartmental knee arthroplasty (UKA) have been reported in the past decade. Therefore, to better counsel this growing population of young patients undergoing knee arthroplasty, an updated understanding of their expected postoperative outcomes is warranted.

QUESTIONS/PURPOSES

In this systematic review, we evaluated (1) all-cause survivorship, (2) reasons for revision, (3) patient-reported outcomes, and (4) return to physical activity and sport in patients 55 years or younger undergoing primary TKA or UKA.

METHODS

A comprehensive search of PubMed, Medline, SportDiscus, and CINAHL was performed to identify all original studies evaluating outcomes after primary knee arthroplasty for young patients (55 years of age or younger) from inception until March 2021. The following keywords were used: knee, arthroplasty, replacement, pain, function, revision, survivorship, sport, physical activity, and return to play. Only original research studies that were related to knee arthroplasty and reported postoperative outcomes with a minimum 1-year follow-up for patients 55 years or younger were included. Unpublished materials, publications not available in English, and studies with a primary diagnosis of rheumatoid arthritis were excluded. The Methodological Index for Non-Randomized Studies (MINORS) score was used to evaluate the study quality of case series and comparative studies, while the Cochrane Risk of Bias tool and the Jadad scale were used for randomized studies. The primary outcomes of interest for this study were all-cause survivorship rate, reasons for all-cause revision, Knee Society and Knee Society Function scores (minimum clinically important difference [MCID] 7.2 and 9.7, respectively), WOMAC scores (MCID 10), Tegner scores (no reported MCID for knee arthroplasty), and return to physical activity or sport. Knee Society and Knee Society Function scores range from 0 to 100, with scores from 85 to 100 considered excellent and below 60 representing poor outcomes. All-cause survivorship rate and reasons for revision were both reported in 17 total studies. Knee Society scores were presented in 19 and Knee Society Function scores were reported in 18 included studies. WOMAC scores and Tegner scores were each found in four included studies, and return to physical activity and return to sport analyses were performed in seven studies. Overall, 21 TKA studies and five UKA studies were included in this analysis, featuring 3095 TKA knees and 482 UKA knees.

RESULTS

Kaplan-Meier estimates of all-cause survivorship ranged from 90% to 98% at 5 to 10 years of follow-up after TKA and from 84% to 99% (95% CI 93% to 98%) at 10 years to 20 years post-TKA. All-cause UKA survivorship was 90% at 10 years and 75% at 19 years in the largest Kaplan-Meier estimate of survivorship for patients younger than 55 who underwent UKA. Common reasons for revision in TKA patients were polyethylene wear/loosening, aseptic tibial loosening, and infection, and in UKA patients the common reasons for revision were knee pain, aseptic loosening, progression of knee osteoarthritis, and polyethylene wear/loosening. Knee Society scores ranged from 85 to 98 for 5-year to 10-year follow-up and ranged from 86 to 97 at 10-year to 20-year follow-up in TKA patients. Knee Society Function scores ranged from 70 to 95 for 5-year to 10-year follow-up and ranged from 79 to 86 at 10-year to 20-year follow-up. Return to physical activity and sport was reported variably; however, most patients younger than 55 have improved physical activity levels after knee arthroplasty relative to preoperative levels.

CONCLUSION

Although all-cause survivorship rates were frequently above 90% and patient-reported outcome scores were generally in the good to excellent range, several studies reported long-term survivorship rates from 70% to 85% and fair patient-reported outcome scores, which must be factored into any preoperative counseling with patients. We could not control for surgeon volume in this report, and prior research suggests that increasing volume is associated with less frequent complications; in addition, the studies we included were variably affected by selection bias, transfer bias, and assessment bias, which makes it likely that the findings of our review represent best-case estimates. To limit the frequency of revision in patients younger than 55 years undergoing TKA, clinicians should be cautious of polyethylene wear/loosening, aseptic tibial loosening, and infection, while knee pain and progression of knee osteoarthritis are also common reasons for revision in patients younger than 55 undergoing UKA. Further research should isolate younger knee arthroplasty patients and evaluate postoperative activity levels while accounting for preoperative physical activity and sport participation.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Prior Anterior Cruciate Ligament Reconstruction Does Not Compromise the Functional Outcomes of Medial Unicompartmental Knee Arthroplasty Although Revision for Progressive Arthritis May Occur Earlier

BACKGROUND

Anterior cruciate ligament (ACL) deficiency is commonly considered a contraindication for unicompartmental knee arthroplasty (UKA). The purpose of this study is to compare the outcomes of UKA after prior ACL reconstruction (rACL cohort) to UKA with an intact native ACL (nACL cohort).

METHODS

Forty-five patients from 3 institutions who underwent medial UKA after prior rACL were matched by age, gender, preoperative function scores, and body mass index to 90 patients who underwent UKA with an intact nACL. Primary outcomes were Knee Injury and Osteoarthritis Outcome Score for Joint Replacement, Oxford Knee Scores, Knee Society Functional Scores, and Kellgren-Lawrence scores in the unresurfaced, lateral tibiofemoral compartment. Secondary outcomes were postoperative complications and the need for revision to TKA.

RESULTS

At a mean of 3.6 years, all PROMs improved significantly with no differences identified between groups. The incidence of revision TKA was similar between cohorts (P = 1.00); however, the mean time to revision for progressive osteoarthritis was 4.0 years in the nACL group and 2.2 years in the rACL group. Twenty percent of rACL patients had a postoperative complication compared to 8% in the nACL group. Despite presenting with a similar degree of lateral arthritis, a greater percentage of patients developed Kellgren-Lawrence scores of ≥3 in the rACL cohort (9%) than in the nACL cohort (0%).

CONCLUSION

A previously reconstructed ACL does not appear to compromise the short-term functional outcomes of UKA; however, there is a higher rate of minor complications and progression of lateral compartment arthritis, which should be considered with patients in the shared decision process.

Tranexamic Acid is Associated With Decreasing the Risk of Complications in Patients Undergoing Arthroplasty With Preoperative Coagulopathy

BACKGROUND

Preoperative coagulopathy is a risk factor for perioperative blood loss. The antifibrinolytic effects of tranexamic acid (TXA) could negate the association between preoperative coagulopathy and adverse outcomes in patients undergoing total joint arthroplasty (TJA). However, no studies have evaluated this relationship. This study compared the perioperative outcomes of coagulopathic patients undergoing TJA who did and did not receive TXA.

METHODS

We retrospectively reviewed 2123 primary TJAs (975 knees and 1148 hips) performed in patients with a preoperative coagulopathy. Coagulopathy was defined as international normalized ratio >1.2, partial thromboplastin time >35 seconds, or platelet count <150,000/μL. TXA was administered in 240 patients and not administered in 1883 patients. Demographics, comorbidities, and surgical details including operative time, blood loss, and thromboprophylaxis agent were recorded. Multivariate regression was used to identify factors associated with 90-day outcomes.

RESULTS

Patients who received TXA had less intraoperative blood loss and 2.3 times decreased risk of 90-day complications (odds ratio [OR] 0.43, 95% confidence interval [CI] 0.20-0.85, P = .021), especially cardiovascular (2.92% vs 12.1%, P <.001) and wound complications (0.0% vs 1.59%, P = .042). TXA was also associated with shorter length of stay (beta 0.74, 95% CI 0.67-0.82, P <.001) and decreased risk of nonhome discharge (OR 0.50, 95% CI 0.29-0.83, P = .009). There was no difference in mortality or 90-day readmissions between the groups.

CONCLUSION

TXA administration decreased the incidence of perioperative complications and resource utilization in patients undergoing arthroplasty with a preoperative coagulopathy identified on preadmission testing. These findings support the broader adoption of TXA in patients undergoing TJA, particularly when the patient has a preoperative coagulopathy.

Octogenarians Undergoing Medial Unicompartmental Knee Arthroplasty Have Similar Patient-Reported Outcomes as Their Younger Counterparts

BACKGROUND

As a procedure with lower surgical morbidity, unicompartmental knee arthroplasty (UKA) may present a practical solution for elderly patients with unicompartmental arthritis. However, few studies have analyzed the results of UKA in the extreme elderly. This study compared the functional and perioperative outcomes between octogenarians and age-appropriate controls undergoing UKA.

METHODS

Prospectively collected data of 44 patients aged ≥80 years who underwent unilateral UKA were analyzed. Each octogenarian was matched 1:3 with 132 patients aged 65-74 years using propensity scores adjusting for gender, body mass index, Charlson comorbidity index, and preoperative scores. Knee Injury and Osteoarthritis Outcome Score for Joint Replacement and Short Form-12 were collected preoperatively and 2 years postoperatively. Complications, reoperations, readmissions, and unplanned visits were recorded up to 1 year postoperatively.

RESULTS

The mean age was 70.0 ± 2.7 years in the control group and 83.0 ± 3.0 years in the octogenarian group (P < .001). The percentage of outpatient procedures was comparable (control 50.0%; octogenarian 45.5%; P = .601). With the exception of poorer Short Form-12 physical scores in octogenarians at 2 years (39.4 ± 14.1 vs 44.9 ± 9.2, P = .028), there was no difference in final postoperative scores or improvement in scores between the groups. The rate of complications, reoperations, readmissions, and emergency room visits was also similar. The five-year survivorship was 97% in the control group and 93% in the octogenarian group (P = .148).

CONCLUSION

Octogenarians undergoing UKA can experience clinical outcomes that are similar to those of their younger counterparts. The clinical trajectory outlined may help clinicians provide valuable prognostic information to elderly patients and guide preoperative counseling.

Patient Resilience Has Moderate Correlation With Functional Outcomes, but Not Satisfaction, After Primary Unilateral Total Knee Arthroplasty

BACKGROUND

As many as 20% of patients who undergo total knee arthroplasty (TKA) are dissatisfied. Psychological factors have been shown to play a role in outcomes after TKA. The purpose of this study was to investigate the impact of patient resilience on functional outcomes and satisfaction after primary unilateral TKA.

METHODS

Eighty-six patients who underwent primary unilateral TKA by a single surgeon were studied. Primary outcomes were the Brief Resilience Scale (BRS), mental health component of the Veterans Rand 12-Item Health Survey (VR-12 MCS), Knee Injury and Osteoarthritis Outcome Score for Joint Replacement, and New Knee Society Score. Correlations between BRS and dependent variables were found by using Spearmen's Rho Correlation testing. Unadjusted and adjusted regressions were run using the delta values as the dependent outcome and the BRS score as the main independent value, with data presented as an estimate of 95% confidence interval P value.

RESULTS

Resilience significantly correlated with male sex (P = .031), preoperative VR-12 MCS scores (P = .013), and postoperative VR-12 MCS scores (P < .001). BRS had moderate correlation with postoperative Knee Society Scores (KSS) Functional Activity Scores, as this approached, but did not achieve statistical significance (P = .062). There was no correlation between BRS and postoperative KSS Patient Expectations score, KSS Patient Satisfaction score, or total postoperative opioid usage.

CONCLUSIONS

Primary TKA patients with greater resilience are more likely to be male and have better mental health characteristics than those with lower resilience. Patients with greater resilience also tended to have improved knee function after TKA, although this was not statistically significant. Resiliency did not correlate with postoperative opioid consumption or patient satisfaction after TKA.

Despite Equivalent Medicare Reimbursement, Facility Costs for Outpatient Total Knee Arthroplasty Are Higher Than Unicompartmental Knee Arthroplasty

BACKGROUND

With the recent removal of total knee arthroplasty (TKA) from the Centers for Medicare and Medicaid Services (CMS) Inpatient Only list, facility reimbursement for outpatient TKA now falls under the Outpatient Prospective Payment System at the same rate as unicompartmental knee arthroplasty (UKA). The purpose of this study was to compare true facility costs of patients undergoing outpatient TKA with those undergoing UKA.

METHODS

We reviewed a consecutive series of 2310 outpatient TKA and 231 UKA patients from 2018 to 2019. Outpatient status was defined as a hospital stay of less than 2 midnights. Facility costs were calculated using a time-driven, activity-based costing algorithm. Implants, supplies, medications, and personnel costs were compared between outpatient TKA and UKA patients. A multivariate analysis was performed to control for confounding medical and demographic variables.

RESULTS

When compared with patients undergoing UKA, outpatient TKA patients had higher implant costs ($3403 vs $3081; P < .001) and overall hospital costs ($6350 vs $5594; P < .001). Outpatient TKA patients had a greater length of stay (1.2 vs 0.5 days; P < .001) and greater postoperative personnel costs ($783 vs $166; P < .001) than UKA patients. When controlling for comorbidities, outpatient TKA was associated with a $803 (P < .001) increase in overall facility costs compared with UKA.

CONCLUSION

Despite equivalent reimbursement from CMS as UKA, outpatient TKA has increased facility costs to the hospital. Although implant costs can vary greatly by institution, CMS should consider appropriately reimbursing outpatient TKA for the additional personnel costs when compared with UKA.

Minimizing Surgical Instrument Burden Increases Operating Room Efficiency and Reduces Perioperative Costs in Total Joint Arthroplasty

BACKGROUND

Optimizing surgical trays to improve operating room efficiency and reduce costs in instrument processing is an under-appreciated strategy for cost containment. This study aimed to assess the economic impact of instrument tray optimization in total joint arthroplasty.

METHODS

Thirty-five randomly selected elective primary total knee arthroplasty and total hip arthroplasty performed by 4 fellowship-trained surgeons were analyzed. Type and number of instruments used as well as timing of different steps in the sterilization process were recorded by an independent observer. Using Lean methodology, surgeons identified redundant or underutilized instruments and agreed upon the fewest number needed for each tray. Instrument utilization rates and processing time were analyzed before and after tray modifications. Annual cost savings were calculated based on a processing factor of $0.59-$11.52 per instrument.

RESULTS

Only 45.5% of instruments opened for total knee arthroplasty were utilized. After optimization, 28 of 87 (32.2%) instruments were removed and the remainder could be stored in one tray. Mean set-up time decreased from 20.7 to 14.2 minutes, while 40-75 minutes were saved during the sterilization process. For total hip arthroplasty, only 36.0% of instruments were utilized. Using Lean methods, 46 of 112 (41.1%) instruments were removed and tray count was reduced to 2 trays. Mean set-up time decreased from 27.9 to 18.6 minutes, while 45-150 minutes were saved during processing. Average annual savings amounted to $281,298.05.

CONCLUSION

Lean methodology can be used to eliminate redundant or underutilized instruments in total joint arthroplasty, improving surgical efficiency and generating substantial cost savings.

Partial Knee Arthroplasty: The State of the Art

Unicompartmental knee arthroplasty and patellofemoral arthroplasty were pioneered in the 1970s but abandoned by most in favor of total knee arthroplasty because of inconsistent early outcomes. Advancements in implant design, instrumentation, indications, and surgical techniques have enhanced results and led to a resurgence in both unicompartmental knee arthroplasty and patellofemoral arthroplasty for appropriate candidates. In appropriately selected patients, current implants and techniques provide surgeons the resources to carry out a surgical procedure that is simpler to perform and easier to recover from. Furthermore, unicompartmental knee arthroplasty is associated with fewer postoperative complications and lower mortality and is equal to or better than total knee arthroplasty.

Cartilage Disease of the Patellofemoral Joint: Realignment, Restoration, Replacement

Chondral lesions of the patellofemoral joint are common, and when symptomatic they can be difficult to manage. Not only are there various degrees of injury with multiple etiologies, but patellofemoral anatomy is complex and the patient's lower extremity alignment may contribute to the pathology. Treatment depends on the location, size, and depth of the lesion and may require realignment or concomitant stabilizing procedures. Tibial tubercle osteotomy can be performed in isolation or combined with various cartilage-based treatments, including marrow stimulation techniques, autologous chondrocyte implantation, osteochondral autograft, and osteochondral allograft. End-stage lesions, failed primary patellofemoral cartilage restoration with diffuse involvement, or isolated primary patellofemoral arthritis may be amenable to treatment with patellofemoral arthroplasty. Recent investigations in properly indicated patients using advanced techniques have shown that management of patellofemoral cartilage disease is now more effective and predictable than in the past.

Formal Physical Therapy Following Total Hip and Knee Arthroplasty Incurs Additional Cost Without Improving Outcomes

BACKGROUND

Recent evidence has demonstrated that formal physical therapy (PT) may not be required for most patients undergoing total hip (THA) and knee (TKA) arthroplasty. This study compared the differences in costs and functional outcomes in patients receiving formal PT and those who did not follow primary THA and TKA.

METHODS

We queried claims data from a single private insurer identifying patients who underwent primary THA or TKA from 2015 to 2017 in our practice. Demographics, comorbidities, number, and cost of PT visits in a 90-day episode of care were recorded. Outcomes were compared between patients using self-directed home exercises, home PT, outpatient PT, or both home and outpatient PT. A multivariate analysis was performed to identify significant predictors of outcomes.

RESULTS

Of the 2971 patients included in analysis, patients using both services had higher 90-day PT costs (mean $2091, P < .001) than those using home PT alone ($1146), outpatient PT alone ($1356), or no formal PT ($0). Home PT had the greatest cost per visit for both private insurance patients ($177/visit) and Medicare Advantage patients ($157/visit), but patients using both home PT and outpatient PT services had the greatest overall PT cost, $2091 for private insurance and $1891 for Medicare Advantage. Patients who used home PT were at significantly higher risk of both complications (odds ratio = 3.21; 95% confidence interval, 2.1-4.9; P < .001) and readmissions (odds ratio = 3.4; 95% confidence interval, 2.1-5.5; P < .001).

CONCLUSION

Participation in formal PT accounts for up to 8% of the episode of care following THA and TKA. The role of formal PT for most patients should take into account the cost-effectiveness of the intervention.

Technology Applications for Arthroplasty: Moving the Field Forward?

Total joint arthroplasty (TJA) is one of the most performed and successful surgeries in the United States for advanced degenerative and inflammatory arthritis with most patients reporting excellent outcomes. However, a large number of patients are still dissatisfied following TJA. To improve outcomes, new technologies such as patient-specific instrumentation and custom implants; smart implant trials; radiologic, computer, and portable accelerometer-based navigation systems; and robotics have been developed. Their overall goals are to avoid the drawbacks of conventional arthroplasty surgery, to simplify the procedures, to improve the accuracy of surgical techniques, to improve outcomes, and to decrease costs. This chapter provides an overview of the current technologies and their applications in TJA.

Rotational alignment errors can occur in unicompartmental knee arthroplasty if anatomical landmarks are misused: A preoperative CT scan analysis

BACKGROUND

Accurate implant positioning, including rotation, is essential for successful unicompartmental knee arthroplasty (UKA). This study defined the rotational error that would result in medial UKA when using the medial edge of the tibial tubercle (TT) rather than the medial tibial spine for determining tibial component rotation, and in lateral UKA when aligning the anterior edge of the sagittal tibial cut with the lateral edge of the patellar tendon.

METHODS

Preoperative computed tomography (CT) scans were reviewed in 88 knees undergoing medial (n = 71) and lateral (n = 17) UKAs. In medial UKA, the angle between a line along the long axis of the medial tibial spine and a line drawn to the medial edge of the TT was measured. In lateral UKA, the angular relationship between the longitudinal axis of the lateral tibial spine and the lateral edge of the patellar tendon was measured.

RESULTS

In medial UKA, an average angular error of 9.6° of external rotation could result if the medial edge of the TT is used to set tibial implant rotation. In lateral UKA, the error of the sagittal tibial cut was an average of 7.1° of excessive external rotation if it is referenced on the lateral edge of the patellar tendon.

CONCLUSIONS

The preoperative CT scan analysis showed that using the medial edge of the TT and lateral edge of the patellar tendon to set tibial implant rotation may result in excessive external rotation in medial and lateral UKAs, which could result in kinematic mismatch, suboptimal contact areas and rotational malalignment.

Unicondylar Knee Arthroplasty Has Fewer Complications but Higher Revision Rates Than Total Knee Arthroplasty in a Study of Large United States Databases

BACKGROUND

Unicondylar knee arthroplasty (UKA) has superior functional outcomes compared to total knee arthroplasty (TKA) with good mid-term and long-term survival data from high-volume institutions. We sought to quantify the risk of complications, re-operation/revision, hospital re-admission for any reason, and mortality of knee arthroplasty patients in the US patient population using 2 large databases.

METHODS

UKA and TKA patients who were identified in the 2002-2011, 5% sample of Medicare data and 2004-2012 (June) MarketScan Commercial and Medicare Supplemental Databases were followed to evaluate the risk of complications, hospital re-admission for any reason, and mortality within 90 days of surgery. Survival probability defined by re-operation was calculated using the Kaplan-Meier method at 0.5, 2, 5, 7, and up to 10 years post-operatively.

RESULTS

Compared to UKA, complication rates for TKA patients were significantly higher, including wound complication, pulmonary embolism, stiffness, peri-prosthetic joint infection, myocardial infarction, re-admission, and death. Age was found to be a significant risk factor (P < .05) for all complications in the Medicare cohort, except stiffness (P = .839), and all complications in the MarketScan cohort, except re-admission (P = .418), whereas gender had a variable effect on complications based on age. Survivorship of UKA was lower than TKA at all time points. Additionally, younger age adversely affected implant survival. By 7 years post-surgery, UKA survivorship in the Medicare and MarketScan cohorts was 80.9% and 74.4%, respectively. In contrast, TKA survivorship for the same cohorts was 95.7% and 91.9% by the same time point.

CONCLUSION

Patients undergoing UKA have fewer post-operative complications and re-admissions than those undergoing TKA. However, patients undergoing UKA have a higher rate of re-operation and revision at up to 10 years of follow-up. It appears that age, as well as surgeon and hospital volume significantly impacts implant survivorship while gender does not have a relation.

LEVEL OF EVIDENCE

Level III.

Low rate of iatrogenic complications during unicompartmental knee arthroplasty with two semiautonomous robotic systems

BACKGROUND

Intraoperative complications due to utilization of robotic assistance during unicompartmental knee arthroplasty have not been reported. While inadvertent soft tissue injury has been reported during total knee and hip arthroplasty with autonomous style robotic systems, the incidence of these problems with semiautonomous (i.e. surgeon-driven) systems is unknown.

METHODS

We report on a series of 1064 consecutive unicompartmental knee arthroplasties performed by one surgeon with either one of two commercially available semiautonomous robotic systems.

RESULTS

There were no soft tissue, bone injuries or other complications related to the use of the robotic bone preparation method. Six complications related to the use of standard computer navigation pins occurred (0.6%) - one pseudoaneurysm of a branch of the tibialis anterior artery, one tibial metaphyseal stress fracture, and four areas of pin site irritation/superficial infection that resolved with a short course of oral antibiotics.

CONCLUSION

Current semiautonomous robotic methods are safe, with few complications using meticulous surgical techniques.

Unicondylar Knee Arthroplasty in the U.S. Patient Population: Prevalence and Epidemiology

Publications on the prevalence of unicompartmental knee arthroplasty in the United States using a single database may have underestimated the "true" number of cases performed, given that several unicondylar knee arthroplasty (UKA) patients are <65 years and have private insurance. The prevalence of UKA in elderly (≥65 years) and younger (<65 years) populations was evaluated using the 2002 to 2011 5% sample of the Medicare data (Part B) and the 2004 to June 2012 MarketScan Commercial and Medicare Supplemental databases, respectively. The prevalence of UKA was stratified by age, gender, census region, Charlson comorbidity index, Medicare buy-in status, and diagnosis. The annual rate of change in the UKA rate was examined using Poisson regression to evaluate temporal changes considering year as a covariate. A total of 5235 and 23,310 UKA procedures were identified from the 5% Medicare and MarketScan databases, respectively. The rates of UKA generally increased until 2008, after which there was a decline. In both cohorts, gender and year of operation were found to be significantly associated with UKA rate. Analysis of data obtained over the past few years revealed that males 55 to 64 years, 65 to 69 years, and 70 to 74 years were the only age-gender groups whose UKA rates appeared to be trending upward. From 2002 to 2011, the rate of UKAs performed in the United States has increased, and a significant proportion of the surgeries were performed in younger (<65 years) patients.

A novel handheld robotic-assisted system for unicompartmental knee arthroplasty: surgical technique and early survivorship

Technology, including robotics, has been developed for use in unicompartmental knee arthroplasty (UKA) to improve accuracy and precision of bone preparation, implant positioning, and soft tissue balance. The NAVIO™ System (Smith and Nephew, Pittsburgh, PA, United States) is a handheld robotic system that assists surgeons in planning implant positioning based on an individual patient’s anatomy and then preparing the bone surface to accurately achieve the plan. The surgical technique is presented herein. In addition, initial results are presented for 128 patients (mean age 64.7 years; 57.8% male) undergoing UKA with NAVIO. After a mean of follow-up period of 2.3 years, overall survivorship of the knee implant was 99.2% (95% confidence interval 94.6–99.9%). There was one revision encountered during the study, which was due to persistent soft tissue pain, without evidence of loosening, subsidence, malposition or infection. These initial results suggest a greater survivorship than achieved in the same follow-up time intervals in national registries and cohort studies, though further follow-up is needed to confirm whether this difference is maintained at longer durations.

Cost-Effectiveness of Surgical and Nonsurgical Treatments for Unicompartmental Knee Arthritis: A Markov Model

BACKGROUND

There has been increased utilization of surgical options for the treatment of end-stage unicompartmental arthritis in patients at both extremes of the age spectrum. The purpose of this study was to determine how these changing paradigms affected the lifetime cost-effectiveness of total knee arthroplasty (TKA), unicompartmental knee arthroplasty (UKA), and nonsurgical treatment (NST).

METHODS

Using a Markov decision analytic model, we assessed how lifetime costs and quality-adjusted life years (QALYs) vary as a function of age at the time of initial treatment (ATIT) of patients with end-stage unicompartmental knee osteoarthritis undergoing TKA, UKA, and NST. Separate models were estimated for ATITs at 5-year intervals from 40 through 90 years. Direct medical costs, QALYs, and transition probabilities were determined from the published literature. Indirect costs (lost wages, Social Security disability collections, and value of missed workdays) were calculated. Cost-effectiveness and incremental cost-effectiveness ratios (ICERs) were calculated for each treatment at each ATIT. The model assumed no crossover from NST to UKA or TKA. ICERs were compared with a willingness-to-pay threshold of 50,000 U.S. dollars, and a 1-way sensitivity analysis was used to assess the robustness of ICER-based treatment decisions. Societal savings were estimated.

RESULTS

In the base-case model, surgical treatments were less expensive and provided a greater number of QALYs than NST from 40 to 69 years of age. From 70 years of age and onward, surgical treatments remained cost-effective compared with NST, with ICERs remaining below the societal willingness-to-pay threshold. When surgical treatments were compared, UKA dominated TKA for all ATITs. The preferential use of UKA in all U.S. patients with unicompartmental osteoarthritis would result in an estimated lifetime societal savings of 987 million to 1.5 billion U.S. dollars per annual wave of patients undergoing treatment.

CONCLUSIONS

In this preliminary assessment, recent expansion of surgical treatments into younger and older age demographics appears to be cost-effective in the setting of unicompartmental knee osteoarthritis. Our findings suggest that NST should be used sparingly in patients below the age of 70 years and UKA should be chosen over TKA in order to maximize cost-effectiveness.

LEVEL OF EVIDENCE

Economic and decision analysis Level IV. See Instructions for Authors for a complete description of levels of evidence.

Pros and Cons: A Balanced View of Robotics in Knee Arthroplasty

In both unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA), compared with conventional techniques robotic technology has been shown to optimize the precision of bone preparation and component alignment, reducing outliers and increasing the percentage of components aligned within 2° or 3° of the target goal. In addition, soft tissue balance can be quantified through a range of motion in UKA and TKA using the various robotic technologies available. Although the presumption has been that the improved alignment associated with robotics will improve function and implant durability, there are limited data to support that notion. Based on recent and emerging data, it may be unreasonable to presume that robotics is necessary for both UKA and TKA. In fact, despite improvements in various proxy measures, the precision of robotics may be more important for UKA than TKA, although if system costs and surgical efficiencies continue to improve, streamlining perioperative processes, reducing instrument inventory, and achieving comparable outcomes in TKA may be a reasonable goal of robotic surgery.

Formal Physical Therapy May Not Be Necessary After Unicompartmental Knee Arthroplasty: A Randomized Clinical Trial

BACKGROUND

The purpose of this randomized clinical trial was to compare formal outpatient physical therapy (PT) and unsupervised home exercises after unicompartmental knee arthroplasty (UKA).

METHODS

Fifty-two patients were randomized to 6 weeks of outpatient PT or an unsupervised home exercise program after UKA. The primary outcome was change in range of motion at 6 weeks with secondary outcomes including total arc of motion, Knee Society Score, Knee Injury and Osteoarthritis Outcome Score Jr, Lower Extremity Functional Scale, and Veterans Rands-12 score.

RESULTS

Twenty-five patients received outpatient PT, 22 patients the self-directed exercise program, while 3 patients deviated from the protocol, 1 patient withdrew, and 1 patient was lost to follow-up. There was no difference in the change of range of motion (P = .43) or total arc of motion at 6 weeks (P = .17) between the groups and likewise no significant differences were found in any of the secondary outcomes. Two patients who crossed over from the unsupervised home exercise program to formal outpatient PT within the first 2 weeks postoperatively required a manipulation under anesthesia.

CONCLUSIONS

Our results suggest self-directed exercises may be appropriate for most patients following UKA. However, there is a subset of patients who may benefit from formal PT.

Stepping Toward Objective Outcomes: A Prospective Analysis of Step Count After Total Joint Arthroplasty

BACKGROUND

Functional recovery monitoring after total hip arthroplasty (THA) and total knee arthroplasty (TKA) is often limited to surgeon-based assessment and patient self-reporting rather than objective measures. However, traditional outcomes may not reliably gauge return of function. The goal of this study was to evaluate and compare an objective measure of postoperative recovery, daily step-count, with patient self-reported outcomes.

METHODS

Prospectively, 589 patients used a mobile step-tracking application to record daily steps. Steps were recorded for 4 weeks before surgery and 12 weeks, thereafter. Patient-reported lower extremity functional scale (LEFS) scores were recorded at 1, 6, and 12 weeks, postoperatively. LEFS scores were correlated to weekly median daily steps using the Spearman rank correlation coefficient.

RESULTS

Preoperative median daily steps were 2682 and 1988 for patients undergoing THA and TKA, respectively. Steps for weeks 1, 6, and 12 were 214, 3,170, and 3884 after THA and 153, 1772, and 2311 after TKA, respectively. Step-count demonstrated a weakly positive correlation with LEFS scores. For week 1, the correlation was 0.27 and 0.29 for THA and TKA patients, respectively. For week 6, the correlation was 0.18 and 0.29 for THA and TKA patients, respectively.

CONCLUSION

Physical function improved over the first 12 weeks as measured by both steps and patient-reported assessments. Postoperative steps weakly correlated with LEFS scores, suggesting patient-reported outcomes may provide only part of the story. Incorporating objective measures may be a valuable addition to the surgeon's armamentarium for monitoring patient recovery.

Periarticular Liposomal Bupivacaine Injection Versus Intra-Articular Bupivacaine Infusion Catheter for Analgesia After Total Knee Arthroplasty: A Double-Blinded, Randomized Controlled Trial

BACKGROUND

Intra-articular bupivacaine hydrochloride (HCl) infusion catheters and periarticular injections of liposomal bupivacaine are often used as postoperative local anesthetics. The purpose of this study was to compare the efficacies of these local anesthetics following total knee arthroplasty.

METHODS

This study was a superiority trial with a randomized, controlled, double-blinded design. Patients were randomly assigned to either delivery of bupivacaine HCl by the ON-Q* Pain Relief System pump (n = 96) or by an injection of Exparel (liposomal bupivacaine) (n = 104). The primary outcome of this study was cumulative narcotic consumption on postoperative days 0 through 3. Narcotic consumption data were collected retrospectively from in-hospital records while patients were in the hospital. Following discharge, narcotic consumption data were gathered from patient surveys, as were secondary outcomes measures.

RESULTS

We did not identify greater narcotic use in the ON-Q* group compared with the Exparel group (p = 0.641). The mean difference between the groups was 0.5 morphine equivalent (95% confidence interval [CI] = -1.7 to +2.8), with the ON-Q* group consuming an average 10.4 morphine equivalents (95% CI = 8.7 to 12.0) compared with 10.9 (95% CI = 9.3 to 12.5) in the Exparel group. There were no significant differences between groups with regard to any of the secondary measures of pain with the exception of pain while walking and pain with physical therapy (p = 0.019 and p = 0.010, respectively), both of which showed an approximately 1-point difference in favor of the ON-Q* group on a visual analog scale (VAS). There were also no differences in the postoperative side effects, including nausea, constipation, or vomiting, or in the rates of study-related complications, patient satisfaction, or length of hospital stay.

CONCLUSIONS

Exparel did not have superior efficacy compared with the ON-Q* Pain Relief System as reflected by narcotic consumption, our primary outcome. There were small significant differences, in favor of the ON-Q* group, in 2 secondary measures of pain during activity, but these approximately 1-point VAS differences are unlikely to be clinically relevant. The choice of a local anesthetic modality should be based on a combination of safety, convenience, and cost considerations.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Preoperative Patellofemoral Chondromalacia is Not a Contraindication for Fixed-Bearing Medial Unicompartmental Knee Arthroplasty

BACKGROUND

Patellofemoral chondromalacia (PFCM) has historically been considered a contraindication for unicompartmental knee arthroplasty (UKA), but there is limited data assessing PFCM's impact on the results of fixed-bearing UKA. Our objective was to assess the impact of medial patellar and/or medial trochlear PFCM on overall and patellofemoral-specific 2-year outcomes after fixed-bearing medial UKA.

METHODS

Intraoperative notes defined the presence and location of PFCM during fixed bearing medial UKA. Outcome measures included the New Knee Society Score (NKSS), Kneeling Ability Score (KAS) and Forgotten Joint Score (FJS-12). Thirty-one knees with PFCM (PFCM group), and 52 knees without PFCM (N-PFCM group) were included for analysis. Mann-Whitney U tests assessed the statistical significance of observed differences, and a Bonferroni correction was applied, adjusting threshold for significance to P = .005.

RESULTS

At minimum follow-up of 2 years, no statistical differences were detected between the N-PFCM and PFCM groups in the postoperative NKSS (159 vs 157, P = .731), preoperative to postoperative NKSS change (P = .447), FJS-12 (70.5 vs 67.6, P = .471), or KAS (71% vs 65%, P = .217). Patients with isolated patellar chondromalacia (n = 13) demonstrated trends toward worse outcomes according to NKSS (147, P = .198), FJS-12 (58, P = .094), and KAS (46%, P = .018), but were statistically insignificant. No failures occurred in either group.

CONCLUSION

Functional outcomes of fixed-bearing medial UKA are not adversely impacted by the presence of PFCM involving the medial patellar facet and/or medial or central trochlea. Further follow-up is needed to determine longer-term implications of fixed-bearing medial UKA in patients with PFCM.

Improvements in Sexual Activity After Total Knee Arthroplasty

BACKGROUND

Sexual limitations in the setting of total knee arthroplasty (TKA) are poorly understood.

METHODS

Surveys were designed to assess preoperative and postoperative sexual function, and limitations were retrospectively administered to 91 sexually active TKA patients at an average of 2.1 years (range, 0.5-4.0) after surgery. Preoperative and postoperative responses were compared using 1-tailed and 2-proportion z tests, with P < .05 as the threshold for significance.

RESULTS

Before TKA, sexual quality and/or frequency was limited in 45% of patients because of their knee. Patients experienced an average 17.1 months (range, 0-60) of sexual limitations before surgery, resulting largely from pain (87%) and diminished range of motion or flexibility (44%). Fifty-five percent of patients reported the need to change their sexual positions to accommodate their knee, with 97% of these patients indicating the need to avoid kneeling during sex. Postoperatively, fewer patients had to adjust their sexual positions to accommodate their knee (55% vs 28%, P = .0005), and avoid bearing weight on the afflicted knee during sex (97% vs 79%, P = .0213). Patients resumed sexual activity after an average of 2.4 months (range, 0-18). Despite these general improvements, 25% of individuals had less sex in the first year after surgery. After 1 year of recovery, however, 60% indicated that they more easily engaged in sexual activity than in the previous year, with 84% of these patients experiencing less pain, and 30% experiencing greater mobility or range of motion.

CONCLUSION

TKA does not eliminate sexual limitations, but it significantly decreases kneeling dysfunction and gives patients more liberty in selecting their sexual positions.

Patellofemoral Arthroplasty: An Evolving Science

Patellofemoral arthroplasty (PFA) has long been a clinical option for patients with isolated patellofemoral arthritis. However, a high rate of failure as a result of patellar instability related to component malposition, soft-tissue imbalance, errant surgical techniques, and poor trochlear implant designs contributed to the underutilization of PFA. The evolution of surgical indications, trochlear implant design, component positioning, and soft-tissue balance has led to improved patellar tracking, fewer failures related to patellar instability, and improved functional outcomes. The development and broad adoption of onlay-style trochlear components, which can be positioned perpendicular to the AP axis of the femur, has substantially improved patellar tracking and, thus, improved the durability of PFA. In addition, favorable data showing success after secondary surgery or revision to total knee arthroplasty after PFA have emerged, which has led to increased use of PFA in appropriately selected patients.

Low-Dose Aspirin Is Effective Chemoprophylaxis Against Clinically Important Venous Thromboembolism Following Total Joint Arthroplasty: A Preliminary Analysis

BACKGROUND

Aspirin is a safe and effective prophylaxis for the prevention of venous thromboembolism following total joint arthroplasty. The optimal dose of aspirin prophylaxis is unknown. Our hypothesis was that lower-dose aspirin is as effective as higher-dose aspirin for the prevention of venous thromboembolism and is associated with fewer gastrointestinal side effects.

METHODS

In a prospective, crossover study, we analyzed 4,651 primary total joint arthroplasty cases performed from July 2013 to June 2015. For 4 weeks, 3,192 patients received enteric-coated 325-mg aspirin twice daily (the 325-mg aspirin group) and 1,459 patients received 81-mg aspirin twice daily (the 81-mg aspirin group). There were no significant differences (p > 0.05) in sex, body mass index, or Charlson Comorbidity Index between the two patient populations. Recorded complications occurring within 90 days postoperatively included symptomatic venous thromboembolism (deep venous thrombosis and pulmonary embolism), gastrointestinal complications, acute periprosthetic joint infection, and death.

RESULTS

The incidence of venous thromboembolism of 0.1% (95% confidence interval [CI], 0% to 0.3%) in the 81-mg aspirin group (1 with deep venous thrombosis and 1 with pulmonary embolism) was not significantly different (p = 0.345) from 0.3% (95% CI, 0.1% to 0.6%) in the 325-mg aspirin group (7 with deep venous thrombosis and 5 with pulmonary embolism). The incidence of gastrointestinal bleeding or ulceration of 0.3% (95% CI, 0% to 0.5%) in the 81-mg aspirin group was slightly, but not significantly (p = 0.66), lower than the 0.4% (95% CI, 0.2% to 0.6%) in the 325-mg aspirin group. The incidence of acute periprosthetic joint infection was 0.2% (95% CI, 0% to 0.4%) in the 81-mg aspirin group compared with 0.5% (95% CI, 0.2% to 0.7%) in the 325-mg aspirin group (p = 0.28). The 90-day mortality rate was similar in both groups at 0.1% (95% CI, 0% to 0.2%) in the 81-mg aspirin group and 0.1% (95% CI, 0% to 0.2%) in the 325-mg aspirin group (p = 0.78).

CONCLUSIONS

Our study demonstrates that low-dose aspirin is not inferior to high-dose aspirin for venous thromboembolism prophylaxis following total joint arthroplasty. This is not unexpected, as the available literature demonstrates that low-dose aspirin is as effective as higher-dose aspirin in the prevention of acute coronary syndrome and cerebrovascular events.

LEVEL OF EVIDENCE

Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Routine Postoperative Laboratory Tests Are Unnecessary After Partial Knee Arthroplasty

BACKGROUND

While partial knee arthroplasty (PKA) is increasingly performed on an outpatient basis, many surgeons still admit patients overnight and obtain laboratory studies on the first postoperative day. The purpose of this study was to investigate the utility and cost effectiveness of routine postoperative laboratory studies after PKA.

METHODS

This is a retrospective review of 322 consecutive unilateral or bilateral simultaneous PKAs (unicompartmental, patellofemoral, and modular bicompartmental knee arthroplasty) performed by a single surgeon. There were 408 complete blood counts and basic metabolic panels ordered.

RESULTS

Despite a large number of laboratory studies ordered and abnormalities detected, there was a 1.6% rate of laboratory-associated interventions (for either hypokalemia or hyperglycemia in 5 patients) and no red blood cell transfusions. Hospital charges associated with laboratory studies totaled $85,413. There were no 90-day postoperative hospital readmissions or emergency department evaluations related to abnormal postoperative laboratory values.

CONCLUSION

With an increasing emphasis placed on cost containment, the low rate of laboratory-associated interventions after PKA suggests that routinely obtaining laboratory studies are neither necessary nor cost effective.

Selective Early Hospital Discharge Does Not Increase Readmission but Unnecessary Return to the Emergency Department Is Excessive Across Groups After Primary Total Knee Arthroplasty

BACKGROUND

There has been much attention paid to the ability to optimize outcomes, limit complications, and reduce costs within the episode of care after total joint arthroplasty. Limiting the duration of postoperative hospitalization as well as reducing emergency department (ED) visits and readmissions are additional considerations in the paradigm of cost containment. Our purpose was to evaluate the safety of early hospital discharge after primary total knee arthroplasty (TKA) and to identify the diagnoses responsible for ED visits and readmissions in the postoperative period.

METHODS

We investigated risk factors for readmission in 995 patients undergoing primary TKA. We compared 2 groups: length of hospital stay (LOS) ≤2 or ≥3 days. Analysis included LOS, Charlson score, history of DVT, discharge disposition, and postdischarge ED visits.

RESULTS

Patients who stayed ≤2 postoperative days had a significantly lower mean Charlson score and more likely discharged home. Charlson score and history of DVT were predictive of return events. Patients discharged to home were less likely to have return events. More than half of the patients evaluated in the ED were not readmitted.

CONCLUSION

Among patients undergoing primary TKA, it is the health of the patient, and not their resultant LOS, that correlates to return events. The ED is overused for complaints that may otherwise be managed as effectively and more cost efficiently in outpatient settings. Cost containment must include unnecessary utilization of the ED.