The Effect of Surgeon and Hospital Volume on Total Knee Arthroplasty Patient-reported Outcome Measures: An American Joint Replacement Registry Study

BACKGROUND

The lower morbidity and mortality rate associated with increased surgeon and hospital volume may also correlate with improved patient-reported outcome measures. The goal of this study was to determine the relationship between surgeon and hospital volume and patient-reported outcome measures after total knee arthroplasty (TKA) using American Joint Replacement Registry data.

METHODS

Using American Joint Replacement Registry data from 2012 to 2020, 8,193 primary, elective TKAs with both preoperative and 1-year postoperative The Knee Injury and Osteoarthritis Outcome Score, Joint Replacement (KOOS-JR) scores were analyzed. This study was powered to detect the minimally clinical important difference (MCID). The main exposure variables were median annual surgeon and hospital volume. Tertiles were formed based on the median annual number of TKAs performed: low-volume surgeons (1 to 52), medium-volume (53 to 114), and high-volume (≥115); low-volume hospitals (1 to 283), medium-volume (284 to 602), and high-volume (≥603). The mean preoperative and 1-year postoperative KOOS-JR were compared. Multivariable logistic regression models were used to determine the effect of surgeon and hospital volume and demographics on achieving the MCID for KOOS-JR.

RESULTS

The mean preoperative and 1-year postoperative KOOS-JR score for low-volume surgeons was 47.78 ± 13.50 and 77.75 ± 16.65, respectively, and 47.32 ± 13.73 and 76.86 ± 16.38 for low-volume hospitals. The mean preoperative and 1-year postoperative KOOS-JR score for medium-volume surgeons was 47.20 ± 13.46 and 76.70 ± 16.98, and 48.93 ± 12.50 and 77.15 ± 16.36 for medium-volume hospitals. The mean preoperative and 1-year postoperative KOOS-JR scores for high-volume surgeons were 49.08 ± 13.04 and 78.23 ± 16.72, and 48.11 ± 13.47 and 78.23 ± 17.22 for high-volume hospitals. No notable difference was observed in reaching MCID for KOOS-JR after adjustment for potential confounders.

CONCLUSION

An increased number of TKA cases performed by a given surgeon or at a given hospital did not have an effect on achieving MCID for KOOS-JR outcomes.

The effect of reduced bone mineral density on elective total hip arthroplasty outcomes

INTRODUCTION

Reduced bone mineral density (BMD) and disruption of normal bony architecture are the characteristics of osteopenia and osteoporosis and in patients undergoing total hip arthroplasty (THA) may cause failure of trabecular ingrowth. The purpose of this study is to evaluate the impact of reduced BMD on outcomes following primary elective THA.

METHODS

A retrospective chart review of 650 elective THAs with a DEXA scan in their electronic health record (EHR) from 2011 to 2020 was conducted at an urban, academic center and a regional, health center. Patients were separated into three cohorts based on their t-score and the World Health Organizations definitions: normal (t-score ≥ - 1), osteopenia (t-score < - 1.0 and > - 2.5), and osteoporosis (t-score ≤ - 2.5). Demographic and outcome data were assessed. Subsidence was assessed for patients with non-cemented THAs. Regression models were used to account for demographic differences.

RESULTS

650 elective THAs, of which only 11 were cemented, were included in the study. Patients with osteopenia and osteoporosis were significantly older than those without (p = 0.002 and p < 0.0001, respectively) and had a lower BMI (p < 0.0001 and p < 0.0001, respectively). PFx was significantly greater in patients with osteoporosis when compared to those with normal BMD (6.5% vs. 1.0%; p = 0.04). No such difference was found between osteoporotic and osteopenic patients. The revision rate was significantly higher for osteoporotic patients than osteopenic patients (7.5% vs. 1.5%; p = 0.04). No such difference was found between the other comparison groups.

CONCLUSION

Patients with osteoporosis were older with reduced BMI and had increased PFx after non-cemented elective THA. Understanding this can help surgeons formulate an appropriate preoperative plan for the treatment of patients with osteoporotic bone undergoing elective THA.

Approach-Based Complication Rates of Total Hip Arthroplasty in the Medicare Population

INTRODUCTION

The direct anterior approach (DAA) has become increasingly more popular for total hip arthroplasty (THA). Critics of the DAA maintain that a higher complication rate exists; however, data collection is prone to bias as the outcome is collected by the surgeons performing either an anterior or posterior approach (PA). This study aims to compare the short-term outcomes, including complication rates, in a Medicare population between THAs performed via DAA and PA.

MATERIALS AND METHODS

Baseline patient data was obtained from our institution's database for bundled payments, an unbiased collection source. A retrospective chart review was conducted on 492 Medicare patients who underwent primary THA between October 2016 and September 2017 to separate patients into DAA and PA cohorts. Descriptive patient characteristics along with surgical and clinical data were collected. Statistical tests for significance were based on either t-tests or chi-squared. To control for demographic variables, a multivariable regression analysis was conducted.

RESULTS

Two hundred forty-one patients were included in the DAA cohort while 251 were included in the PA cohort. Surgical time (74.39 vs. 103.03 minutes; p < 0.001) and length-of-stay (1.29 vs. 2.74 days; p < 0.001) in patients who underwent the DAA was revealed to be statistically lower compared to the PA cohort. Patients in the DAA cohort were statistically more likely to be discharged to home health agencies (HHA) or self-care compared to those in the PA cohort (93.4% vs.74.5%; p < 0.001). There were no statistical differences in 90-day readmission rates or morphine milligram equivalents per day between both cohorts.

CONCLUSION

The DAA to THA resulted in shorter surgical time, length-of-stay, and increased likelihood of discharge to HHA or self-care when compared with the PA. There were no differences in opioid consumption and complications leading to 90-day readmission.

The Risk of Acute Infection Following Intra-Articular Corticosteroid Injection During Total Knee Manipulation Under Anesthesia

BACKGROUND

Manipulation under anesthesia (MUA) is an established option for improving motion in patients presenting with early stiffness following total knee arthroplasty (TKA). Intra-articular corticosteroid injections (IACI) are sometimes administered adjunctively, yet literature examining their efficacy and safety remains limited.

STUDY DESIGN

Retrospective, Level IV METHODS: A total of 209 patients (TKA = 230) were retrospectively examined to determine the incidence of prosthetic joint infections (PJI) within 3 months following manipulation with IACI. Approximately 4.9% of initial patients had inadequate follow-up where the presence of infection could not be determined. Range of motion (ROM) was assessed in patients who had follow-up at or beyond 1 year (n=158) and was recorded over multiple time points.

RESULTS

No infections (0 of 230) were identified within 90 days of receiving IACI during TKA MUA. Before receiving TKA (pre-index) patients averaged 111⁰ of total arc of motion (TAM) and 113⁰ of flexion. Following index procedures, just prior to manipulation (pre-MUA), patient's averaged 83⁰ and 86⁰ of total arc and flexion motion respectively. At final follow-up, patients averaged 110⁰ of TAM and 111⁰ of flexion. At 6 weeks following manipulation, patients had gained a mean of 25⁰ and 24⁰ of their total arc and flexion motion found at 1 year. This motion was preserved through a 12 month follow-up period.

CONCLUSION

Administering IACI during TKA MUA does not harbor an elevated risk for acute PJI. Additionally, its use is associated with substantial increases in short-term ROM at 6 weeks following manipulation, which remains preserved through long-term follow-up.

Aspirin thromboprophylaxis following primary total knee arthroplasty is associated with a lower rate of early prosthetic joint infection compared with other agents

BACKGROUND

Patients undergoing total knee arthroplasty (TKA) are at increased risk of venous thromboembolism (VTE). Aspirin has been shown to be effective at reducing rates of VTE. In select patients, more potent thromboprophylaxis is indicated, which has been associated with increased rates of bleeding and wound complications. This study aimed to evaluate the effect of thromboprophylaxis choice on rates of early prosthetic joint infection (PJI) following TKA.

METHODS

A review of 11,547 primary TKA patients from 2013 to 2019 at a single academic orthopaedic hospital was conducted. The primary outcome measure was PJI within 90 days of surgery as measured by Musculoskeletal Infection Society criteria. There were 59 (0.5%) patients diagnosed with early PJI. Chi-square and Welch-Two Sample t-tests were used to determine statistically significant relationships between thromboprophylaxis and demographic variables. Significance was set at p<0.05. Multivariate logistic regression adjusted for age, body mass index, sex, and Charlson comorbidity index was performed to identify and control for independent risk factors for early PJI.

RESULTS

There was a statistically significant difference in the rates of early PJI between the aspirin and non-aspirin group (0.3 vs 0.8%, p<0.001). Multivariate logistic regressions revealed that patients given aspirin thromboprophylaxis had significantly lower odds of PJI (odds ratios (OR)=0.51, 95% Confidence Interval (CI) 0.29 to 0.89, p=0.019) compared to non-aspirin patients.

CONCLUSIONS

The use of aspirin thromboprophylaxis following primary TKA is independently associated with a lower rate of early PJIs. Arthroplasty surgeons should consider aspirin as the gold standard thromboprophylaxis in all patients in which it is deemed medically appropriate and should carefully weigh the morbidity of PJI in patients when non-aspirin thromboprophylaxis is considered.

Impact of revision TKA indications on resource utilization

BACKGROUND

Indications for surgery may impact resource utilization in aseptic revision total knee arthroplasty (rTKA), and understanding these relationships would facilitate risk-stratification preoperatively. The purpose of this study was to investigate the impact of rTKA indications on readmission, reoperation, length of stay (LOS), and cost.

METHODS

We reviewed all 962 patients who underwent aseptic rTKA at an academic orthopedic specialty hospital between June 2011-April 2020 with at least 90 days of follow-up. Patients were categorized based on their indication for aseptic rTKA as listed in the operative report. Demographics, surgical factors, LOS, readmission, reoperation and cost were compared between cohorts.

RESULTS

There were significant differences in operative time among cohorts (p < 0.001), highest among the periprosthetic fracture group (164.2 ± 59.8 min). Reoperation rate was greatest in the extensor mechanism disruption cohort (50.0 %, p = 0.009). Total cost differed significantly among groups (p < 0.001), which was highest among the implant failure cohort (134.6 % of mean) and lowest for component malpositioning cohort (90.2 % of mean). Similarly, there were significant differences in direct cost (p < 0.001) which was highest in the periprosthetic fracture cohort (138.5 % of mean), and lowest in the implant failure cohort (90.5 % of mean). There were no differences in discharge disposition, or number of re-revisions among all groups.

CONCLUSIONS

Operative time, components revised, LOS, readmissions, reoperation rate, total cost and direct cost following aseptic rTKA varied significantly between different revision indications. These differences should be noted for preoperative planning, resource allocation, scheduling, and risk-stratification.

LEVEL OF EVIDENCE

III, retrospective observational analysis.

The effect of losartan on range of motion and rates of manipulation in total knee arthroplasty: a retrospective matched cohort study

INTRODUCTION

Arthrofibrosis remains a common cause of patient dissatisfaction and reoperation after total knee arthroplasty (TKA). Losartan is an angiotensin receptor blocker (ARB) with inhibitory effects on transforming growth factor beta, previously implicated in tissue repair induced fibrosis, and has been studied to prevent stiffness following hip arthroscopy. This study aimed to evaluate pre- and postoperative range of motion (ROM) and the incidence of manipulation under anesthesia (MUA) following primary TKA in patients taking Losartan preoperatively for hypertension.

MATERIALS AND METHODS

A retrospective review of 170 patients from 2012 to 2020 who underwent a primary, elective TKA and were prescribed Losartan at least three months prior to surgery. All patients who were prescribed Losartan and had a preoperative and postoperative ROM in their chart were included and were matched to a control group of patients who underwent TKA and had no Losartan prescription. ROM, MUA, readmissions, reoperations, and revisions were assessed using chi-square and independent sample t tests.

RESULTS

Seventy-nine patients met the inclusion criteria. Preoperative ROM was similar between patients on Losartan and the control group (103.59° ± 16.14° vs. 104.59° ± 21.59°, respectively; p = 0.745). Postoperative ROM and ΔROM were greater for patients prescribed Losartan (114.29° ± 12.32° vs. 112.76° ± 11.65°; p = 0.429 and 10.57° ± 14.95° vs. 8.17° ± 21.68°; p = 0.422), though this difference did not reach statistical significance. There was no difference in readmission, rate of manipulation for stiffness, or all-cause revision rates.

CONCLUSION

In this study, we found that the use of Losartan did not significantly improve postoperative ROM, reduce MUA or decrease revision rates. Further prospective studies using Losartan are required to elucidate the potential effects on ROM and incidence of arthrofibrosis requiring MUA.

LEVEL III EVIDENCE

Retrospective cohort study.

Comparative Analysis of Outcomes in Medicare-Eligible Patients with a Hospital Stay Less than Two-Midnights versus Longer Length of Stay following Total Knee Arthroplasty: Implications for Inpatient-Outpatient Designation

The Centers for Medicaid and Medicare Services (CMS) removed primary total knee arthroplasty (TKA) from the inpatient-only list in January 2018. This study aims to compare outcomes in Medicare-aged patients who underwent primary TKA and had an in-hospital stay spanning less than two-midnights to those with a length of stay greater than or equal to two-midnights. We retrospectively reviewed 4,138 patients ages ≥65 who underwent primary TKA from 2016 to 2020. Two cohorts were established based on length of stay (LOS), those with an LOS <2 midnights were labeled outpatient and those with an LOS ≥2 midnights were labeled inpatient as per CMS designation. Demographic, clinical data, knee injury and osteoarthritis outcome score for joint replacement (KOOS, JR), and veterans RAND 12 physical and mental components (VR-12 PCS & MCS) were collected. Demographic differences were assessed with Chi-square and independent sample t-tests. Clinical data and KOOS, JR and VR-12 PCS and MCS scores were compared by using multilinear regression analysis, controlling for demographic differences. There were 841 (20%) patients with a LOS < 2 midnights and 3,297 (80%) patients with a LOS ≥ 2 midnights. Patients with a LOS < 2 midnights were significantly younger (71.70 vs. 73.06; p < 0.001), more likely male (42.1 vs. 25.7%; p < 0.001), Caucasian (68.8 vs. 57.7%; p <0.001), have lower BMI (30.80 vs. 31.92; p < 0.001), Charlson Comorbidity Index (CCI; 4.62 vs. 4.96; p < 0.001), and American Society of Anesthesiologists (ASA) class II or higher (p < 0.001). These patients were more likely to be discharged home compared to patients with LOS ≥ 2 midnights (95.8 vs. 73.1%; p < 0.001). Patients who stayed ≥ 2 midnights reported lower patient-reported outcome scores at all time-periods (preoperatively, 3 months and 1 year), but these differences did not exceed the minimum clinically important difference. Mean improvement preoperatively to 1 year postoperatively in KOOS, JR (22.53 vs. 25.89; p < 0.001), and VR-12 PCS (12.16 vs. 11.49; p = 0.002) was statistically higher for patients who stayed < 2 midnights, though these differences were not clinically significant. All-cause ED visits (p = 0.167), 90-day all-cause readmissions (p = 0.069) and revision (p = 0.277) did not statistically differ between the two cohorts. TKA patients classified as outpatient had similar quality metrics and saw similar clinical improvement following TKA with respect to most patient reported outcome measures, although they were demographically different. Outpatient classification is more likely to be assigned to younger males with higher functional scores, lower BMI, CCI, and ASA class compared with inpatients. This Retrospective Cohort Study shows level III evidence.

Comparison of silver-embedded occlusive dressings and negative pressure wound therapy following total joint arthroplasty in high BMI patients: a randomized controlled trial

INTRODUCTION

High body mass index (BMI) and wound drainage following total joint arthroplasty (TJA) can lead to wound healing complications and periprosthetic joint infection. Silver-embedded occlusive dressings and negative pressure wound therapy (NPWT) have been shown to reduce these complications. The purpose of this prospective trial was to compare the effect of silver-embedded dressings and NPWT on wound complications in patients with BMI ≥ 35 m/kg2 undergoing TJA.

METHODS

We conducted a randomized control trial of patients who had a BMI > 35 m/kg² and were undergoing primary TJA between October 2017 and February 2020. Patients who underwent revision surgery, or those with an active infection, previous scar, history of wound healing complications, post-traumatic degenerative joint disease with hardware, or inflammatory arthritis were excluded. Patients were randomized to receive either a silver-embedded occlusive dressing (control) or NPWT. Frequency distributions, means, and standard deviations were used to describe patient demographics, postoperative complications, 90-day readmissions, and reoperations. T-test and chi-squared tests were used to test for significant differences between continuous and categorical variables, respectively.

RESULTS

Two hundred-thirty patients with 3-month follow-up were included. One-hundred-fifteen patients received the control and 115 patients received NPWT. There were six patients (5.2%) in the control group with wound complications (drainage: n = 5, non-healing wound: n = 1) and two patients (1.7%) in the NPWT with complications (drainage: n = 2). There were no 90-day readmissions in the control group versus two (1.8%) 90-day readmissions in the NPWT group. Finally, three patients (2.6%) in the control group underwent reoperations (irrigation and debridement [I&D], I&D with modular implant exchange, and implant revision), while none in the NPWT group had undergone reoperation. The two groups showed insignificant differences in wound complications (p = 0.28), 90-day readmissions (p = 0.50), and reoperations (p = 0.25).

CONCLUSION

Patients with BMI ≥ 35 m/kg2 undergoing TJA have no statistical difference in early wound complications, readmissions, or reoperations when treated with either silver-embedded dressings or NPWT.

The Impact of Patient Resilience on Discharge After Total Hip Arthroplasty

BACKGROUND

Patients who undergo total hip arthroplasty (THA) require resilience to recover and resume daily functions. Increased resilience may be an important factor for achieving improved outcomes. The purpose of this study is to examine the impact of resilience on time to discharge and on early patient-reported outcomes following primary THA.

METHODS

A retrospective review of patients who underwent primary THAs and completed the Brief Resilience Scale (BRS) was conducted from 2020 to 2021 at an urban, academic hospital. Patients were separated into 3 cohorts based on BRS score: low (1-2.99), normal (3-4.30), and high (4.31-5) resilience. Demographics, participation in same-day discharge (SDD) program, length of stay (LOS), and preoperative and 3-month postoperative scores on the Hip Disability and Osteoarthritis Outcome Score Joint Replacement (HOOS JR) were assessed. SDD patients were excluded from LOS analysis.

RESULTS

A total of 393 patients were included. Compared to low resilience patients, odds of being enrolled in SDD program were 1.49 and 3.01 times higher (P = .01) and 3-month HOOS JR scores improved by 4.7% and 11.7% (P = .03) for normal and high resilience patients, respectively. As resilience increased from low to normal to high in non-SDD patients, LOS significantly decreased (53.27 ± 51.92 vs 38.70 ± 28.03 vs 25.64 ± 14.48 hours, respectively; P = .001).

CONCLUSION

Increased resilience is positively associated with likelihood of SDD participation or decreased LOS. Increased resilience was associated with increased HOOS JR scores at 3 months, although this did not reach the minimal clinically important difference. The BRS may be a useful tool for predicting patients who can successfully participate in SDD or predicting LOS after primary THA.

The Effect of Femoral Head Size on Groin Pain in Total Hip Arthroplasty

BACKGROUND

Although increased femoral head size reduces the risk of instability in total hip arthroplasty (THA), it may lead to iliopsoas irritation and increased anterior groin pain. The purpose of this study is to compare outcomes between non-modular dual-mobility (NDM) implants and small (≤32 mm) and large (≥36 mm) fixed-bearing (FB) constructs.

METHODS

A retrospective review of all primary total hip arthroplasties from 2011 to 2021 was conducted at a single, urban academic institution. Patients were separated into 3 cohorts: NDM implant ≤32 mm and FB implant ≥36 mm. Demographics and outcomes such as length of stay, dislocation, and anterior groin pain were assessed. Patients were deemed as having groin pain if they received an iliopsoas injection or had extended physical therapy ordered beyond 3 months postoperatively.

RESULTS

There were 178 NDM implants, 936 ≤32-mm FB, and 2,454 ≥36-mm FB implants included. Length of stay significantly differed between the groups (48.4 ± 43.3 vs 63.2 ± 40.6 vs 57.2 ± 38.1 hours; P = .001). Although not statistically significant, the ≥36-mm FB cohort had the highest rate of dislocations (0.6% vs 0.7% vs 0.9%; P = .84). Although no patients with an NDM implant received an iliopsoas injection, 9 patients (0.9%) with a ≤32-mm FB implant and 9 patients (0.4%) with a ≥36-mm implant received an injection (P = .06). However, 18 (10.1%) patients with an NDM implant, 304 (32.5%) patients with a ≤32-mm FB implant, and 355 (14.5%) patients with a ≥36-mm FB implant received extended physical therapy 3 months after surgery (P < .001).

CONCLUSION

NDM implants, as well as FB implants with both small and large head sizes are effective at preventing dislocation. NDM implants did not result in an increase in anterior groin pain compared to ≤32-mm and ≥36-mm FB constructs.

LEVEL III EVIDENCE

Retrospective cohort study.

Documented and Undocumented Psychiatric Conditions Affect the Length of Stay and Discharge Disposition Following Total Hip Arthroplasty

BACKGROUND

Despite increased efforts toward patient optimization, some patients have undocumented conditions that can affect costs and quality metrics for institutions and physicians. This study evaluates the effect of documented and undocumented psychiatric conditions on length of stay (LOS) and discharge disposition following total hip arthroplasty (THA).

METHODS

A retrospective review of all primary THAs from 2015 to 2020 at a high-volume academic orthopedic specialty hospital was conducted. Patients were separated into 3 cohorts: patients with a documented psychiatric diagnosis (+Dx), patients without a documented psychiatric diagnosis but with an actively prescribed psychiatric medication (-Dx), and patients without a psychiatric diagnosis or medication (control). Patient demographics, LOS, and discharge disposition were assessed.

RESULTS

A total of 5309 patients were included; 3048 patients had no recorded psychiatric medications (control); 2261 patients took at least 1 psychiatric medication, of which 1513 (65.9%) and 748 (34.1%) patients were put in the -Dx and +Dx cohorts, respectively. American Society of Anesthesiologists class differed between groups (P < .001). The -Dx and +Dx groups had increased LOS (3.15 ± 2.37 [75.6 ± 56.9] and 3.12 ± 2.27 [74.9 ± 54.5] vs 2.42 ± 1.70 [57.6 ± 40.8] days (hours), P < .001) and were more likely to be discharged to a secondary facility (23.0% and 21.7% vs 13.8%, P < .001) than the control group. Outcomes did not significantly differ between the -Dx and +Dx cohorts.

CONCLUSION

Most THA patients' psychiatric diagnoses were not documented. The presence of psychiatric medications was associated with longer LOS and a greater likelihood of discharge to secondary facilities. This has implications for both cost and quality metrics. Review of medications can help identify and optimize these patients before surgery.

LEVEL III EVIDENCE

Retrospective Cohort Study.

National Football League Wide Receivers and Running Backs Have Decreased Production Following ACL Reconstruction: An Evaluation of Fantasy Football Performance as an Outcome Measure

Purpose

To use fantasy football points as a simple measure alongside on-field statistics to compare performance in National Football League (NFL) offensive skill position players before and after anterior cruciate ligament (ACL) reconstruction.

Methods

A retrospective review of all NFL quarterbacks (QB), running backs (RB), wide receivers (WR), and tight ends (TE) who sustained an isolated, unilateral ACL injury from 1988 to 2017 was conducted. Data were collected from public data sources, team releases, NFL injury reports, press releases, and other Internet resources. For each player, a matched control with similar demographics was identified. Their in-game performance post-ACL reconstruction was analyzed using fantasy football points as an outcome measure.

Results

A total of 13 QBs, 30 RBs, and 29 WRs who underwent ACL reconstruction from 1988 to 2017 and who met inclusion criteria were retrospectively identified and reviewed. Of the 13 quarterbacks included in the study, there was no statistically significant difference in fantasy football points between the pre- and post-ACL reconstruction groups, as well as post-ACL and matched control groups. There was a statistically significant decrease in career fantasy football performance of running backs post-ACL reconstruction compared with matched control groups (129.6 vs 553.6; P < .0001). There was also a statistically significant decrease in per game fantasy football points post-ACL reconstruction (4.4 vs 11.2; P < .0001). Lastly, WRs also demonstrated a decrease in career fantasy football performance post-ACL reconstruction compared with matched controls (145.3 vs 460.9; P = .002). In addition, they also had a decrease in per game fantasy football performance (5.0 vs 7.7; P = .042).

Conclusions

Quarterbacks did not have a statistically significant decrease in performance following ACL reconstruction based on fantasy football performance. Conversely, both running backs and wide receivers had decreased per game and career performance post-ACL reconstruction based on their fantasy football statistics. Furthermore, RBs had the largest decline in production each season over a 3-year period following ACLR compared to QBs and WRs, respectively.

Level of Evidence

Level III, case-control study.

The influence of obesity on achievement of a 'forgotten joint' following total knee arthroplasty

INTRODUCTION

Obesity has been associated with poorer outcomes following total knee arthroplasty (TKA); however, data remain sparse on its impact on patients' joint awareness following surgery. This study aims to investigate the impact of body mass index (BMI) on improvement in outcomes following TKA as assessed by the Forgotten Joint Score-12 (FJS-12).

MATERIALS AND METHODS

We retrospectively reviewed 1075 patients who underwent primary TKA from 2017 to 2020 with available postoperative FJS-12 scores. Patients were stratified based on their BMI (kg/m²): < 30, 30.0-34.9 (obese class I), 35.0-39.9 (obese class II), and ≥ 40 (obese class III). FJS-12 and KOOS, JR scores were collected at various time points. Demographic differences were assessed with Chi-square and ANOVA tests. Mean scores between BMI groups were compared using univariate ANCOVA, controlling for observed demographic differences.

RESULTS

Of the 1075 patients included, there were 457 with a BMI < 30, 331 who were obese class I, 162 obese class II, and 125 obese class III. There were no statistical differences in FJS-12 scores between the BMI groups at 3 months (27.24 vs. 25.33 vs. 23.57 vs. 22.48; p = 0.99), 1 year (45.07 vs. 41.86 vs. 40.51 vs. 36.22; p = 0.92) and 2 years (51.31 vs. 52.86 vs. 46.17 vs. 44.97; p = 0.94). Preoperative KOOS, JR scores significantly differed between the various BMI categories (49.33 vs. 46.63 vs. 44.24 vs. 39.33; p < 0.01); however, 3-month (p = 0.20) and 1-year (p = 0.13) scores were not statistically significant. Mean improvement in FJS-12 scores from 3 months to 2 years was statistically greatest for obese class I patients and lowest for obese class III patients (24.07 vs. 27.53 vs. 22.60 vs. 22.49; p = 0.01). KOOS, JR score improvement from baseline to 1 year was statistically greatest for obese class III patients and lowest for non-obese patients (22.34 vs. 25.49 vs. 23.77 vs. 27.58; p < 0.01).

CONCLUSION

While all groups demonstrated postoperative improvement, those with higher BMI reported lower mean FJS-12 scores but these differences were not found to be significant. Our study showed no significant impact of BMI on postoperative joint awareness, which implies that obese patients, in all obesity classes, experience similar functional improvement following TKA.

LEVEL III EVIDENCE

Retrospective Cohort Study.

Early, Mid-Term, and Late-Term Aseptic Femoral Revisions After THA: Comparing Causes, Complications, and Resource Utilization

BACKGROUND

Registry data suggest increasing rates of early revisions after total hip arthroplasty (THA). We sought to analyze modes of failure over time after index THA to identify risk factors for early revision.

METHODS

We identified 208 aseptic femoral revision THAs performed between February 2011 and July 2019 using an institutional database. We compared demographics, diagnoses, complications, and resource utilization between aseptic femoral revision THA occurring within 90 days (early), 91 days to 2 years (mid), and greater than 2 years (late) after index arthroplasty.

RESULTS

Early revisions were 33% of revisions at our institution in the time period analyzed. Periprosthetic fractures were 81% of early, 27% of mid, and 21% of late femoral revisions (P < .01). Women were more likely to have early revisions than men (75% vs 53% of mid and 48% of late revisions; P < .01). Patients who had early revisions were older (67.97 ± 10.06) at the time of primary surgery than those who had mid and late revisions (64.41 ± 12.10 and 57.63 ± 12.52, respectively, P < .01). Index implants were uncemented in 99% of early, 96% of mid, and 64% of late revisions (P < .01). Early revisions had longer postoperative length of stay (4.4 ± 3.3) than mid and late revisions (3.0 ± 2.2 and 3.7 ± 2.1, respectively, P = .02). In addition, 58% of early revisions were discharged to an inpatient facility compared with 36% of mid and 41% of late revisions (P = .03).

CONCLUSION

Early aseptic femoral revisions largely occur in older women with uncemented primary implants and primarily due to periprosthetic fractures. Reducing the incidence of periprosthetic fractures is critical to decreasing the large health care utilization of early revisions.

Factors Affecting Range of Motion After Revision Total Knee Arthroplasty

BACKGROUND

Range of motion (ROM) after revision total knee arthroplasty (RTKA) is an important clinical outcome, as decreased ROM can lead to patient dissatisfaction and diminished mobility. This study sought to determine the effect of type of revision, implant constraint level, and reason for revision has on RTKA ROM.

METHODS

A retrospective review of 832 RTKA cases from 2011 to 2019 was conducted at a single, urban academic institution. Patients who underwent aseptic RTKA and had preoperative and 1-year postoperative ROM in their chart were included. The ΔROM was calculated by subtracting the preoperative ROM from the 1-year postoperative ROM. ROM was compared between tibial polyethylene liner-only revisions (liner) and all other revision types (component) and based on reason for revision. Subanalysis was performed within the liner and component revision cohorts to determine the effect of reason for revision and implant constraint level on ROM.

RESULTS

In total, 290 patients qualified. Forty-two patients had liner revisions (14.5%) and 248 had component revisions (85.5%). The ΔROM for component revision cases was significantly higher than liner exchange only (10° ± 24° vs.1° ± 19°; P = .03). ΔROM was not significant when comparing the level of implant constraint nor was it when separating and comparing by type of revision. Component revisions due to instability were found to significantly decrease ΔROM.

CONCLUSION

Component revision cases have significantly improved ΔROM when compared with liner-only revision. Constraint level is not significantly associated with changes in ROM in either liner or component revisions. Component revisions due to instability significantly reduce ΔROM.

Is Surgical Approach for Primary Total Hip Arthroplasty Associated With Timing, Incidence, and Characteristics of Periprosthetic Femur Fractures?

BACKGROUND

Periprosthetic femur fractures (PFF) involving primary total hip arthroplasty (THA) remain a significant concern. The purpose of this study was to evaluate the effect of surgical approach during primary THA on early PFF with respect to fracture timing, incidence, radiographic parameters, and surgery-related factors.

METHODS

A retrospective review of all patients with PFF during or after primary THA from 2011 to 2019 was conducted at a single, urban academic institution. Of the study cohort of 11,915 patients, 79 patients with PFF were identified (0.66%). Direct anterior (DA), posterior anterior (PA), and laterally based (LA) cohorts were formed based on the surgical approach. PA and LA groups were combined to form a nonanterior (NA) cohort. Radiographic parameters, surgical factors, and fracture mechanism were analyzed.

RESULTS

The incidence of fracture across approaches was 0.70% (33/4707; DA), 0.63% (35/5600; PA), and 0.68% (11/1608; LA) (P = .97). Time from THA to fracture was significantly shorter in the DA cohort (12.5 ± 14.1 days) than the NA cohort (48.2 ± 120.6 days) (P = .05). Postoperatively identified, atraumatic PFFs were more common in the DA cohort (78.3%, 18/23) than the NA cohort (51.6%, 16/31) (P = .045). There were no differences between groups in radiographic or other clinical parameters.

CONCLUSION

Patients who underwent DA THA have significantly shorter time to PFF and were more often identified postoperatively with an atraumatic mechanism than patients who underwent NA approaches. The known difficulty in femoral exposure and stem placement with the DA approach may play a role in contributing to a higher rate of intraoperative or early postoperative PFF.

Femoral Neck Notching in Dual Mobility Implants: Is This a Reason for Concern?

BACKGROUND

Dual mobility (DM) total hip arthroplasty (THA) implants have been advocated for patients at risk for impingement due to abnormal spinopelvic mobility. Impingement against cobalt-chromium acetabular bearings, however, can result in notching of titanium femoral stems. This study investigated the incidence of femoral stem notching associated with DM implants and sought to identify risk factors.

METHODS

A multicenter retrospective study reviewed 256 modular and 32 monoblock DM components with minimum 1-year clinical and radiographic follow-up, including 112 revisions, 4 conversion THAs, and 172 primary THAs. Radiographs were inspected for evidence of femoral notching and to calculate acetabular inclination and anteversion. Revisions and dislocations were recorded.

RESULTS

Ten cases of femoral notching were discovered (3.5%), all associated with modular cylindrospheric cobalt-chromium DM implants (P = .049). Notches were first observed radiographically at mean 1.3 years after surgery (range 0.5-2.7 years). Notch location was anterior (20%), superior (60%), or posterior (20%) on the prosthetic femoral neck. Notch depth ranged from 1.7% to 20% of the prosthetic neck diameter. Eight cases with notching had lumbar pathology that can affect spinopelvic mobility. None of these notches resulted in stem fracture, at mean 2.7-year follow-up (range 1-7.6 years). There were no dislocations or revisions in patients with notching.

CONCLUSION

Femoral notching was identified in 3.5% of DM cases, slightly surpassing the dislocation rate in a cohort selected for risk of impingement and instability. Although these cases of notching have not resulted in catastrophic failures thus far, further study of clinical sequelae is warranted. Component position, spinopelvic mobility, and implant design may influence risk.

In a Bundled Payment Model, the Costs Associated With Total Joint Replacement in Those Aged Older Than 80 Years Are Significantly Greater

BACKGROUND

The number of octogenarians requiring a total hip arthroplasty (THA) and/or total knee arthroplasty (TKA) will rise disproportionally in the coming decade. Although outcomes are comparable with younger patients, management of these older patients involves higher medical complexity at a greater expense to the hospital system. The purpose of this study was to compare the cost of care for primary THA and TKA in our bundled care patients aged ≥80 years to those aged 65-80 years.

METHODS

A retrospective review of primary TKA (n = 641) and THA (n = 1225) cases from 2013 to 2017 was performed. Patient demographic and admission cost data were collected. Patients were grouped based on surgery type (ie, elective or nonelective THA/TKA) and age group (ie, older [≥80 years old] or younger [65-80 years old]). Multivariate regression analyses were used to account for demographic differences.

RESULTS

Elective primary THA in the older cohort (n = 157) cost 24.5% more than the younger cohort (n = 1025) (P < .0001). Elective primary TKA cases in the older cohort (n = 87) cost 17.0% more than the younger cohort's (n = 554) (P < .0001). For nonelective THA cases, the older cohort's (n = 29) episodes cost 39.1% more than the younger cohort (n = 14) (P < .0001). When comparing the <80 elective THA cohort (n = 1025) to the ≥90 cohort (n = 10), the cost difference swelled to 58.7% (P < .0001).

CONCLUSION

Although primary THA and TKA in ≥80-year-old patients yield similar outcomes, this study demonstrates that the additional measures required to care for older patients and ensure successful outcomes cost significantly more. Consideration should be given to age as a factor in determining reimbursement in a bundled payment system to reduce the incentive to restrict care to elderly patients.

Impact of Obesity on the Forgotten Joint Score Following Primary Total Hip Arthroplasty

BACKGROUND

Obesity is a growing public health concern. This study aims to identify the association of body mass index (BMI) on postoperative Forgotten Joint Score-12 (FJS-12) in patients undergoing primary total hip arthroplasty (THA).

METHODS

We retrospectively reviewed 2130 patients at a single urban, academic, tertiary institution who underwent primary THA from 2016-2020 with available postoperative FJS-12 scores. Patients were stratified into two groups based on their BMI (kg/m²):<30 (nonobese) and ≥30 (obese). FJS-12 scores were collected postoperatively at 3 months, 1 year, and 2 years. Demographic differences were assessed with chi-square and independent sample t-tests. Mean scores between the groups were compared using multilinear regression analysis, controlling for demographic differences.

RESULTS

Of the 2130 patients included, 1378 were nonobese, and 752 were obese. Although obese patients reported lower FJS-12 scores all time periods, there were no statistical differences between the two groups at 3 months (53.61 vs 49.62;P = .689), 1 year (68.11 vs 62.45; P = .349), and 2 years (73.60 vs 65.58; P = .102). A subanalysis comparing patients who were of normal BMI (<25), overweight (25.0-29.9), and obese (≥30) followed a similar inverse trend in scores but showed no statistical differences at all postoperative time points (3m:P = .612,1y:P = .607,2y:P = .253). Mean improvement in FJS-12 scores from 3 months to 1 year (14.50 vs 12.83; P = .041), 1 year to 2 years (5.49 vs 3.13; P = .004), and from 3 months to 2 years (20.00 vs15.96; P < .001) were significantly greater for nonobese patients compared to obese patients.

CONCLUSION

While obesity trended toward lower FJS-12 scores, the differences in scores were not statistically significant compared to nonobese patients. BMI did not influence overall FJS-12 scores; however, obese patients achieved a slightly smaller statistical improvement during the first 2 years, though this may not be clinically significant.

LEVEL III EVIDENCE

Retrospective Cohort Study.

The Inaccuracy of ICD-10 Coding in Revision Total Hip Arthroplasty and Its Implication on Revision Data

BACKGROUND

The International Statistical Classification of Diseases, 10th Revision (ICD-10), was adopted by the United States on October 1, 2015 and expanded coding from 3800 codes with the International Statistical Classification of Diseases, Ninth Revision, procedure code system (ICD-9-PCS) to 73,000. The increase in number of codes was designed to create more accurate representations of procedures like revision total hip arthroplasties (rTHAs). However, many worry that the increased complexity leads to more inaccurate coding. The purpose of this study is to determine the accuracy of ICD-10-PCS coding for rTHA and discuss the implications on registry data.

METHODS

The rTHA databases at 2 large, academic medical centers were retrospectively reviewed for all rTHAs between October 1, 2015 and July 3, 2019. The laterality and specific revised components were recorded and compared with the ICD-10-PCS codes used for each procedure. The accuracy of ICD-10-PCS codes relative to the surgical record was determined using coding guidelines published by the American Joint Replacement Registry (AJRR).

RESULTS

Overall, 895 cases were reviewed. Replacement coding was 22% accurate (195 of 895). For removal and replacement coding, accuracy dropped to 17% (152 of 895). All procedures had at least 1 rTHA trigger code that would signify correctly to AJRR that an rTHA occurred.

CONCLUSION

In this study, the percent of correctly coded rTHA was low. All rTHA procedures had at least 1 AJRR trigger code; therefore, an rTHA would have been appropriately captured by AJRR. But these inaccuracies should make one pause when using ICD-10-PCS procedural data to try to evaluate specific rTHA details from administrative claims databases and ward against expanding ICD-10-PCS as a means to collect implant survival and registry data.

Epigenetic Mechanisms Underlying the Aging of Articular Cartilage and Osteoarthritis

Aging is a progressive and complicated bioprocess with overall decline in physiological function. Osteoarthritis (OA) is the most common joint disease in middle-aged and older populations. Since the prevalence of OA increases with age and breakdown of articular cartilage is its major hallmark, OA has long been thought of as "wear and tear" of joint cartilage. Nevertheless, recent studies have revealed that changes in the chondrocyte function and matrix components may reduce the material properties of articular cartilage and predispose the joint to OA. The aberrant gene expression in aging articular cartilage that is regulated by various epigenetic mechanisms plays an important role in age-related OA pathogenesis. This review begins with an introduction to the current understanding of epigenetic mechanisms, followed by mechanistic studies on the aging of joint tissues, epigenetic regulation of age-dependent gene expression in articular cartilage, and the significance of epigenetic mechanisms in OA pathogenesis. Our recent findings on age-dependent expression of 2 transcription factors, nuclear factor of activated T cell 1 (NFAT1) and SOX9, and their roles in the formation and aging of articular cartilage are summarized in the review. Chondrocyte dysfunction in aged mice, which is mediated by epigenetically regulated spontaneous reduction of NFAT1 expression in articular cartilage, is highlighted as an important advance in epigenetics and cartilage aging. Potential therapeutic strategies for age-related cartilage degeneration and OA using epigenetic molecular tools are discussed at the end.