Robotic-assisted total hip arthroplasty utilizing a fluoroscopy-guided system resulted in improved intra-operative efficiency relative to a computerized tomography-based platform.

Robotic-assisted total hip arthroplasty (THA) using a computerized-tomography (CT) based workflow increases surgical time relative to traditional manual technique. The purpose of this investigation was to compare the intra-operative efficiencies of two robotic THA systems: a fluoroscopy-based platform (FL-RTHA) and a contemporary, CT-based (CT-RTHA) platform. A review of 107 consecutive FL-RTHA and 159 CT-RTHA primary, direct anterior approach (DAA) THA procedures was conducted. All cases were performed by one of two surgeons operating at the same institution, for a pre-operative diagnosis of osteoarthritis, avascular necrosis, or rheumatoid arthritis. Primary outcome variables included averages and consistencies (variances) for surgical times and operating room (OR) times. A secondary outcome was to quantify the duration of robot-active phases in the FL-RTHA workflow. The FL-RTHA cohort experienced shorter surgical times (38.71 min ± 7.00 vs. 75.33 min ± 11.38; p < 0.001) and OR times (101.35 min ± 12.22 vs. 156.74 min ± 17.79; p < 0.001) compared to the CT-RTHA cohort. Surgical times and OR times were both more consistent in the FL-RTHA cohort compared to the CT-RTHA cohort (p < 0.001). Patients who underwent DAA THA with the assistance of a fluoroscopy-based robotic system experienced shorter and more consistent surgical times and OR times compared to patients who underwent similar DAA THA procedures with a contemporary, CT-based robotic platform.

Chitranjan S. Ranawat Award: Tourniquet Use Does Not Impact Trajectory of Total Knee Arthroplasty Early Recovery: A Prospective, Randomized Controlled Trial.

BACKGROUND: The impact of tourniquet use on recovery after total knee arthroplasty (TKA) remains controversial. The purpose of this prospective, single blinded, randomized controlled trial was to investigate the effect of tourniquet use on early recovery after TKA using a smartphone app-based patient engagement platform (PEP) with a wrist-based activity monitor to obtain more robust data on early recovery. METHODS: There were 107 patients undergoing primary TKA for osteoarthritis who were enrolled (54 tourniquet [TQ+]; 53 no tourniquet [TQ-]). All patients utilized a PEP and wrist-based activity sensor for 2 weeks preoperatively and 90 days postoperatively to collect Visual Analog Scale (VAS) pain scores and opioid consumption, as well as weekly Oxford Knee Score (OKS) and monthly Forgotten Joint Score (FJS). There was no difference in demographics between groups. Formal physical therapy assessments were performed preoperatively and 3 months postoperatively. Independent sample t-tests were used for continuous data and Chi-square and Fisher's exact tests were used for discrete data. RESULTS: Tourniquet use did not have a statistically significant impact on daily VAS pain or opioid consumption during the first 30 days postoperatively (P > .05). Tourniquet use did not have a significant impact on OKS or FJS at 30 or 90 days postoperatively (P > .05), or on performance of formal physical therapy testing at 3 months postoperatively (P > .05). CONCLUSION: Using a digital technology to collect daily patient data, we found that tourniquet use has no clinically significant negative impact on pain and function in the first 90 days after primary TKA.

The learning curve for a novel, fluoroscopy-based robotic-assisted total hip arthroplasty system.

BACKGROUND: Adoption of robotic-assisted total hip arthroplasty (RA-THA) systems can improve the accuracy of acetabular cup placement, but no group has reported the learning curve of novel, fluoroscopy-based RA-THA systems. METHODS: A learning-curve cumulative summation (LC-CUSUM) analysis was performed on a consecutive series of the first 100 patients who received fluoroscopy-based RA-THA by the study surgeon. Operative times and specific robotic timepoints were compared between learning and proficiency phases. RESULTS: Implementation of fluoroscopy-based RA-THA was associated with a learning curve of 12 cases. A 6-min increase in operative time was seen during the learning phase compared to the proficiency phase (44.3 ± 4.4 vs. 38.0 ± 7.1 min; p < 0.001), with a 3-min longer robotic cup impaction sequence during the learning phase (7.8 ± 1.9 vs. 4.8 ± 1.3 min; p < 0.001). CONCLUSION: Adoption of fluoroscopy-based RA-THA is associated with a brief learning curve of 12 cases, with the most significant improvements in surgical efficiency realised during acetabular cup placement.

James A. Rand Young Investigator's Award: Questioning the "Nickel Free" Total Knee Arthroplasty.

BACKGROUND: A study was performed to measure metal ions present in the knee joint after performing a total knee arthroplasty (TKA) with standard cobalt chromium (CoCr) components as well as with "nickel-free" oxidized zirconium femoral and titanium tibial (OxZr/Ti) components. METHODS: Knee joint fluid was collected prior to arthrotomy, and on postoperative day one to determine the amount of metal debris generated when performing a TKA with standard instrumentation from consecutive cases with CoCr components (n = 24) and OxZr/Ti components (n = 16). RESULTS: CoCr implant patients had statistically higher levels of nickel (Ni) (29.7%, P = .033), cobalt (Co), (1,100.7%, P < .0001) and chromium (Cr) (118.9%, P < .0001) postoperatively. The cutting blocks and sawblades do not contain Co, which therefore must have come from the components. The metal ions generated from the sawblades and cutting blocks, therefore, could be discerned from the OxZr/Ti whose components don't contain Co, Cr, or Ni. The OxZr patients had significantly higher Cr (9.5×, P < .001) and Ni (5.1×, P < .001) post-TKA vs pre-TKA; Co levels were not significantly different as expected with the absence of Co in the components (P = .60). The Ni levels generated in performing an Oxinium TKA was 3.3 times higher than when performing a CoCr TKA (1.37 vs. 41 ppb, P < .001). CONCLUSIONS: The substantial degree of Ni generation resulting from performing a hypoallergenic "nickel-free" TKA calls into questions the rationale of utilizing more expensive lower Ni components on the basis of known or suspected Ni or Cr allergy.

The Impact of Component Design and Fixation on Stress Shielding After Modern Total Knee Arthroplasty.

BACKGROUND: Total knee arthroplasty (TKA) tibial baseplate thickness, metallurgy, and implant fixation with cement may influence stress shielding. The purpose of the present study is to compare bone mineral density of 2 cemented and press-fit TKA designs with differing tibial baseplate thicknesses and metallurgy over a 2-year period to assess for changes in stress shielding. METHODS: One-hundred one TKAs were performed in this Institutional Review Board-approved, prospective study. There were 4 cohorts: DePuy Attune cemented and press-fit, and Stryker Triathlon cemented and press-fit. The Attune tibial baseplate was thicker; both cemented tibial and femoral components were cobalt-chromium. The DePuy Attune press-fit had a cobalt-chromium sintered bead porous coating while the Stryker Triathlon was 3-dimensional printed highly porous titanium alloy. All patients had quantitative dual-energy X-ray absorptiometry scans performed at baseline (4-6 weeks postoperatively) and at 1 and 2 years postoperatively. Stress shielding was evaluated by comparing percent change in bone mineral density in 11 radiographic zones over 2 years. RESULTS: Over a 2-year period, there were no differences in stress shielding on the tibial side in either cemented or press-fit between Stryker Triathlon and DePuy Attune; however, there were differences on the femoral side. The press-fit tibial components of the Stryker Triathlon and DePuy Attune had either similar or less stress shielding over a 2-year period compared to their cemented counterparts. CONCLUSION: This study comparing 2 TKA implants with differing tibial tray thickness did not find significant differences in tibial stress shielding between designs. There was a difference in stress shielding on the femoral side between designs, suggesting that longer term follow-up is warranted.

Does the Patient-Reported Outcomes Measurement Information System Correlate to Legacy Scores in Measuring Mental Health in Young Total Hip Arthroplasty Patients?

Background: Mental health is becoming increasingly important in patient outcomes. The patient reported outcome measurement information system (PROMIS) was developed by the NIH to collect outcome data in rapid dynamic fashion on electronic platforms. The potential role of PROMIS in monitoring young total hip arthroplasty (THA) patients is under-investigated. The purpose of this study is to investigate correlations between PROMIS Depression or Anxiety with SF-12 mental component score. Methods: We identified 223 hips (200 patients) who underwent primary THA over a 30-month period at a single institution. Patients without preoperative PROMIS or SF-12 mental scores, or >50yo were excluded. All data was collected preoperatively and included age, sex, BMI, ASA, PROMIS Depression, PROMIS Anxiety, and SF-12 Mental component score. We considered floor and ceiling effects as significant if >15% of patients responded with the lowest or highest possible score, respectively. Relationships between SF-12 and PROMIS were investigated using correlation (R), and were considered strong if R>0.7. Results: Mean age was 41-years-old, mean ASA category was 2, mean BMI was 30kg/m2, and 54% were female. None of the PROMs showed any floor/ceiling effects at baseline. PROMIS Depression showed a strong correlation to SF-12 Mental (R=-0.72) while PROMIS Anxiety showed a moderate correlation to SF-12 Mental (R=-0.58). Negative linear relationships were observed because a lower PROMIS Depression/Anxiety values indicates less depressive/anxious feelings (inverse of SF-12). Conclusion: PROMIS Anxiety and Depression correlate well with SF-12 mental. These PROMIS domains may be attractive alternatives to legacy mental health instruments in young THA patients. Level of Evidence: III.

Telemedicine for Hip Preservation Patients: Access, Ability and Preference.

Background: Recent events have resulted in rapid rises in the use of telemedicine in orthopaedic surgery, despite limited evidence regarding patient preferences or concerns. The purpose of this study is to determine access to and, ability to use telemedicine technology in an adult hip preservation patient population, as well as determine associations with patient characteristics. Additionally, we seek to understand patients' perceived benefits, risks and preferences of telemedicine. Methods: We performed a cross-sectional survey administered on patients scheduled to undergo joint preservation surgery by one of three surgeons at a single academic institution. Both preoperative and postoperative established patients were included and called for a telephone administered survey if a date of surgery was scheduled between October 1, 2019 and March 30, 2020 and were 18 years or older. The survey had seven sections with 45 questions relating to demographics, technology access, videoconferencing capability, confidence using technology, telehealth experiences, perceptions. Results: 101 patients completed the survey (48% response rate, 101/212). Overall, 99% of participants reported using the internet, 94% reporting owning a device capable of videoconferencing, and 86% of patients had participated in a video call in the past year. When asked for their preferred method for a physician visit: 79% ranked in-person as their first choice and 16% ranked a videoconference visit as their first choice. Perceived benefits of telemedicine visits included reduced travel to appointments (97% agree) and reduced cost of attending appointments (69% agree). However, patients were concerned that they would not establish the same patient-physician connection (51% agree) and would not receive the same level of care (38% agree) through telemedicine visits versus in person visits. Conclusion: The majority of hip preservation patients have access to and are capable of using the technology required for telemedicine visits. However, patients still prefer to have in person visits over concerns that they will not establish the same patient-physician connection and will not receive the same level of care. Telemedicine visits in hip preservation patients may be most attractive to return patients with an established doctor-patient relationship, particularly those with concerns for long distances of travel and associated costs.Level of Evidence: III.

Does the Patient-Reported Outcomes Measurement Information System Correlate to Legacy Scores in Measuring Physical Health in Young Total Hip Arthroplasty Patients?

BACKGROUND: The Patient-Reported Outcomes Measurement Information System (PROMIS) was developed by the National Institutes of Health to collect outcome data in rapid dynamic fashion on electronic platforms. The potential role of PROMIS in monitoring pain and function in young total hip arthroplasty (THA) patients has been under-investigated. The purpose of this study is to investigate correlation between PROMIS Physical Function (PF) and PROMIS Pain Interference (PI) and legacy scores with similar considerations. METHODS: We identified 298 hips who underwent primary THA over 40 months. Patients without preoperative PROMIS or legacy scores, or >50 years were excluded. Demographic data included age, gender, and body mass index. Outcome data included PF, PI, modified Harris Hip Score (mHHS), Western Ontario and McMasters Universities Osteoarthritis Index (WOMAC) domains, and Short Form 12 components. Floor/ceiling effects were considered to be significant if ≥15% of patients responded with the lowest or highest possible score. Spearman correlation (R) was performed to investigate correlation between legacy scores and PROMIS domains. RESULTS: Mean age was 40 years, mean body mass index was 30.1 kg/m2, and 55% were female. None of the patient-reported outcome measures showed any floor/ceiling effects. PI showed moderate correlation to mHHS (R = -0.60), WOMAC Pain (R = -0.62), and WOMAC PF (R = -0.60). PF showed moderate correlation to mHHS (R = 0.66) and WOMAC PF (R = 0.55). Mean PF and PI scores differed significantly from the general population mean of 50 (36.7, 65.4, respectively; both P < .001). CONCLUSION: PROMIS is an attractive alternative to legacy scoring measures, showing moderate correlations between PROMIS physical domains and legacy PROMs of WOMAC and mHHS in young patients undergoing THA.

The Impact of Psychological Factors and Their Treatment on the Results of Total Knee Arthroplasty.

➤: There is a growing body of evidence implicating psychosocial factors, including anxiety, depression, kinesiophobia, central sensitization, and pain catastrophizing, as negative prognostic factors following total knee arthroplasty (TKA). ➤: Symptoms of anxiety and depression likely represent risk factors for negative outcomes in patients undergoing TKA. However, few studies have assessed the impact of preoperative interventions for these conditions on postoperative outcomes. ➤: The Tampa Scale of Kinesiophobia and the Central Sensitization Inventory have demonstrated value in the diagnosis of kinesiophobia and central sensitization. Higher preoperative indices of kinesiophobia and central sensitization predict worse patient-reported outcomes postoperatively. ➤: Although evidence is limited, cognitive-behavioral therapy for kinesiophobia and duloxetine for central sensitization may help to diminish the negative impact of these preoperative comorbidities. It is important to note, however, that outside the realm of TKA, cognitive-behavioral therapy has been recognized as a more effective treatment for central sensitization than medical treatment. ➤: Awareness of these issues will allow surgeons to better prepare patients regarding postoperative expectations in the setting of a comorbid psychosocial risk factor. Further research into the role of preoperative assessment and possible treatment of these conditions in patients undergoing TKA is warranted.

Telemedicine for patients undergoing arthroplasty : access, ability, and preference.

AIMS: The purpose of this study was to determine the access to and ability to use telemedicine technology in adult patients undergoing total hip arthroplasty (THA) and total knee arthroplasty (TKA), and to determine associations with the socioeconomic characteristics of the patients, including age, sex, race, and education. We also sought to understand the patients' perceived benefits, risks, and preferences when dealing with telemedicine. METHODS: We performed a cross-sectional survey involving patients awaiting primary THA and TKA by one of six surgeons at a single academic institution. Patients were included and called for a telephone-administered survey if their surgery was scheduled to be between 23 March and 2 June 2020, and were aged > 18 years. RESULTS: The response rate was 52% (189 of 363 patients). A total of 170 patients (90.4%) reported using the internet, 177 (94.1%) reported owning a device capable of videoconferencing, and 143 (76.1%) had participated in a video call in the past year. When asked for their preferred method for a consultation, 155 (82.8%) and 26 (13.9%) ranked in-person and a videoconference as their first choice, respectively. The perceived benefits of telemedicine consultations included reduced travel to appointments (165 (88.2%) agreed) and reduced cost of attending appointments (123 (65.8%) agreed). However, patients were concerned that they would not establish the same patient-physician connection (100 (53.8%) agreed), and would not receive the same level of care (52 (33.2%) agreed) using telemedicine consultations compared with in-person consultations. CONCLUSION: Most patients undergoing arthroplasty have access to and are capable of using the technology required for telemedicine consultations. However, they still prefer in-person consultations due to concerns that they will not establish the same patient-physician connection and will not receive the same level of care, despite the benefits of reducing the time spent in travelling and the cost of attending appointments, and the appointments being easier to attend. Cite this article: Bone Joint J 2021;103-B(7 Supple B):98-102.

Primary total hip arthroplasty via the direct anterior approach in the lateral decubitus position : surgical technique, learning curve, complications, and early results.

AIMS: The direct anterior approach (DAA) for total hip arthroplasty (THA) has potential advantages over other approaches and is most commonly performed with the patient in the supine position. We describe a technique for DAA THA with the patient in the lateral decubitus position and report the early clinical and radiological outcomes, the characteristics of the learning curve, and perioperative complications. METHODS: All primary DAA THAs performed in the lateral position by a single surgeon over a four-year period from the surgeon's first case using the technique were identified from a prospectively collected database. Modified Harris Hip Scores (mHHS) were collected to assess clinical outcome, and routine radiological analysis was performed. Retrospective review of the medical records identified perioperative complications, the characteristics of the learning curve, and revisions. RESULTS: A total of 257 patients were included in the study. Their mean age was 60 years (SD 9.0). A total of 164 (64%) were female. The mean mHHS improved significantly from 52.1 (SD 16.2) preoperatively to 94.4 (SD 11) at a follow-up of one year (p < 0.001), with 212 of 225 patients (94%) achieving a minimal clinically important difference (MCID) (> 8 points). Radiological evaluation showed a mean leg length discrepancy of 2.6 mm (SD 5.9) and a mean difference in femoral offset of 0.2 mm (SD 4.9). A total of 234/243 acetabular components (96.3%) were positioned within Lewinnek's safe zone. Analysis of operating time, blood loss, the position of the components, and complications did not identify a learning curve. A total of 14 patients (5.4%) had a major perioperative complication and three (1.2%) required revision THA. There were no major neurovascular complications and no dislocations. CONCLUSION: We have described and analyzed a surgical technique for undertaking DAA THA in the familiar lateral decubitus position using a routine operating table, positioning devices, and instrumentation, and shown that it can be performed safely and effectively under these circumstances. Cite this article: Bone Joint J 2021;103-B(7 Supple B):53-58.

Is Apixaban Safe and Effective for Venous Thromboembolism Prophylaxis After Primary Total Hip and Total Knee Arthroplasties?

BACKGROUND: Venous thromboembolism (VTE) is a serious complication of total hip arthroplasty (THA) and total knee arthroplasty (TKA). Apixaban is approved for VTE prophylaxis. This study seeks to ascertain the risk of VTE and bleeding complications in patients undergoing primary THA and TKA receiving apixaban for postoperative VTE prophylaxis for one of the following indications: high risk for VTE, previously on apixaban, and contraindication to the use of aspirin. METHODS: This is a retrospective cohort study of patients who underwent primary THA or TKA over a 17-month period and were prescribed apixaban for thromboprophylaxis postoperatively. RESULTS: 230 patients were included in the study, 110 TKA and 120 THA. The primary reasons for high-risk VTE status included personal and family history of VTE, and 13% were taking apixaban preoperatively for atrial fibrillation. 1 patient (0.43%) who underwent TKA had a DVT with PE. 2.6% of patients had wound complications requiring operative treatment, and 0.87% of THA patients underwent revision arthroplasty. CONCLUSION: The use of apixaban for VTE prophylaxis after primary THA and TKA in patients at high risk for VTE, in patients previously on apixaban, and in patients with a contraindication to the use of aspirin is associated with a low risk of VTE and bleeding complications.

Radiological outcomes following manual and robotic-assisted unicompartmental knee arthroplasty.

AIMS: The purpose of this study was to compare the radiological outcomes of manual versus robotic-assisted medial unicompartmental knee arthroplasty (UKA). METHODS: Postoperative radiological outcomes from 86 consecutive robotic-assisted UKAs (RAUKA group) from a single academic centre were retrospectively reviewed and compared to 253 manual UKAs (MUKA group) drawn from a prior study at our institution. Femoral coronal and sagittal angles (FCA, FSA), tibial coronal and sagittal angles (TCA, TSA), and implant overhang were radiologically measured to identify outliers. RESULTS: When assessing the accuracy of RAUKAs, 91.6% of all alignment measurements and 99.2% of all overhang measurements were within the target range. All alignment and overhang targets were simultaneously met in 68.6% of RAUKAs. When comparing radiological outcomes between the RAUKA and MUKA groups, statistically significant differences were identified for combined outliers in FCA (2.3% vs 12.6%; p = 0.006), FSA (17.4% vs 50.2%; p < 0.001), TCA (5.8% vs 41.5%; p < 0.001), and TSA (8.1% vs 18.6%; p = 0.023), as well as anterior (0.0% vs 4.7%; p = 0.042), posterior (1.2% vs 13.4%; p = 0.001), and medial (1.2% vs 14.2%; p < 0.001) overhang outliers. CONCLUSION: Robotic system navigation decreases alignment and overhang outliers compared to manual UKA. Given the association between component placement errors and revision in UKA, this strong significant improvement in accuracy may improve implant survival. Level of Evidence: III Cite this article: Bone Jt Open 2021;2-3:191-197.

Allergies, Preoperative Narcotic Use, and Increased Age Predict Failed Same-Day Discharge After Joint Replacement.

BACKGROUND: Identifying predictors of failed same-day discharge (SDD) is critical for patient selection. We evaluated patient factors associated with failure of SDD in patients undergoing elective total joint arthroplasty (TJA) in a hospital setting. METHODS: We retrospectively reviewed consecutive patients who underwent primary total knee arthroplasty (TKA) and total hip arthroplasty (THA) between January 31, 2018 and February 1, 2020 by one of the 3 fellowship-trained arthroplasty surgeons. Patient demographics, comorbidities, and clinical data were collected. Analysis was performed to assess risk factors for failed SDD. RESULTS: In total, 2615 TJAs (1425 TKAs, 1190 THAs) were performed over the study period. Two hundred seventy-one (10.4%) were SDDs (80 TKAs, 191 THAs). There were fewer TKAs than THAs (5.6% vs 16.1%, P < .001). Forty-five patients failed SDD (16.6%). Failure rates were similar in TKA and THA (18.8%, 15.7%, P = .54). The most common reasons for failure of SDD were hypotension (11, 24.4%), delayed resolution of spinal anesthesia (11, 24.4%), and nausea (5, 11.1%). Age over 70 years (P = .007), greater than 2 self-reported allergies (P < .001), and preoperative narcotic use (P = .01) were associated with failure of SDD. Gender, body mass index, American Society of Anesthesiologists class, and prior TJA were not significantly associated (P > .05). CONCLUSION: Success of SDD was greater than 80%. Hypotension, delayed resolution of spinal anesthesia, and nausea accounted for 60% of failures of SDD. Patients >70 years, those with >2 self-reported drug allergies, or patients who used preoperative narcotics were at high risk for failure of SDD after THA or TKA.

Is the Patient-Reported Outcome Measurement Information System Feasible in Bundled Payment for Care Improvement Total Knee Arthroplasty Patients?

BACKGROUND: Several bundled payment plans, like the Bundled Payment for Care Improvement (BPCI) initiative for total joint arthroplasty, have been introduced to decrease costs and improve clinical care. Measuring clinical outcomes with efficient, standardized methodologies is essential to determine the relative value of total joint arthroplasty care. We investigated feasibility and responsiveness of the recently developed Patient-Reported Outcomes Measurement Information System (PROMIS) in total knee arthroplasty (TKA) patients. METHODS: We included patients with preoperative and 1-year PROMIS Physical Function (PF), Pain Interference (PI), and Depression (DEP) scores who received unilateral primary TKA. Burden was assessed using the number of questions and time required for PROMIS completion. The minimum clinically important difference was defined as 5. Floor/ceiling effects were noted if more than 15% of patients responded with the lowest/highest possible score, respectively. Wilcoxon rank-sum test was used to compare categorical data. Analysis of variance was used for PROMIS comparisons. RESULTS: In total, 172 knees (54 BPCI) were included. Floor effects were identified for DEP at baseline (non-BPCI) and follow-up (both groups), and for PI at follow-up only (BPCI). Patients required 140 seconds and 16 questions to answer all 3 PROMIS domains. Sixty-seven percent, 60%, and 44% of knees achieved minimum clinically important difference in PI, PF, and DEP scores respectively, with no significant difference between groups. The BPCI cohort was older (P < .001) with a higher American Society of Anesthesiologists score (P = .028). There were no significant differences in scores between BPCI and non-BPCI patients. CONCLUSION: PROMIS is feasible and time-efficient in BPCI patients undergoing primary TKA. There were no significant differences in outcomes between BPCI and non-BPCI knees. LEVEL OF EVIDENCE: Level III.

The burden and utility of routine follow-up at one year after primary arthroplasty.

AIMS: Routine surveillance of primary hip and knee arthroplasties has traditionally been performed with office follow-up visits at one year postoperatively. The value of these visits is unclear. The present study aims to determine the utility and burden of routine clinical follow-up at one year after primary arthroplasty to patients and providers. METHODS: All patients (473) who underwent primary total hip (280), hip resurfacing (eight), total knee (179), and unicompartmental knee arthroplasty (six) over a nine-month period at a single institution were identified from an institutional registry. Patients were prompted to attend their routine one-year postoperative visit by a single telephone reminder. Patients and surgeons were given questionnaires at the one-year postoperative visit, defined as a clinical encounter occurring at nine to 15 months from the date of surgery, regarding value of the visit. RESULTS: Compliance with routine follow-up at one year was 35%. The response rate was over 80% for all questions in the patient and clinician surveys. Overall, 75% of the visits were for routine surveillance. Patients reported high satisfaction with their visits despite the general time for attendance, including travel, being over four hours. Surgeons found the visits more worthwhile when issues were identified or problems were addressed. CONCLUSION: Patient compliance with follow-up at one year postoperatively after primary hip and knee is low. Routine visits of asymptomatic patients deliver little practical value and represent a large time and cost burden for patients and surgeons. Remote strategies should be considered for routine postoperative surveillance primary hip and knee arthroplasties beyond the acute postoperative period. Cite this article: Bone Joint J 2020;102-B(7 Supple B):85-89.

Pelvic rotation after total hip arthroplasty is dynamic and variable.

AIMS: The aims of this study were to determine the change in the sagittal alignment of the pelvis and the associated impact on acetabular component position at one-year follow-up after total hip arthroplasty (THA). METHODS: This study represents the one-year follow-up of a previous short-term study at our institution. Using the patient population from our prior study, the radiological pelvic ratio was assessed in 91 patients undergoing THA, of whom 50 were available for follow-up of at least one year (median 1.5; interquartile range (IQR) 1.1 to 2.0). Anteroposterior radiographs of the pelvis were obtained in the standing position preoperatively and at one year postoperatively. Pelvic ratio was defined as the ratio between the vertical distance from the inferior sacroiliac (SI) joints to the superior pubic symphysis and the horizontal distance between the inferior SI joints. Apparent acetabular component position changes were determined from the change in pelvic ratio. A change of at least 5° was considered clinically meaningful. RESULTS: Pelvic ratio decreased (posterior tilt) in 54.0% (27) of cases, did not change significantly in 34.0% (17) of cases, and increased (anterior tilt) in 12.0% (6) of cases when comparing preoperative to one-year postoperative radiographs. This would correspond with 5° to 10° of abduction error in 22.0% of cases and > 10° of error in 6.0%. Likewise, this would correspond with 5° to 10° of version error in 22.0% of cases and > 10° of error in 44.0%. CONCLUSION: Pelvic sagittal alignment is dynamic and variable after THA, and these changes persist to the one-year postoperative period, altering the orientation of the acetabular component. Surgeons who individualize the acetabular component placement based on preoperative functional radiographs should consider that the rotation of the pelvis (and thus the component version and inclination) changes one year postoperatively. Cite this article: Bone Joint J 2020;102-B(7 Supple B):47-51.

High Prevalence of Radiographic Outliers and Revisions with Unicompartmental Knee Arthroplasty.

BACKGROUND: Alignment outcomes and their impact on implant survival following unicompartmental knee arthroplasty (UKA) are unclear. The purpose of this study was to assess the implant survival and radiographic outcomes after UKA as well as the impact of component alignment and overhang on implant survival. METHODS: We performed a retrospective analysis of 253 primary fixed-bearing and mobile-bearing medial UKAs from a single academic center. All UKAs were performed by 2 high-volume fellowship-trained arthroplasty surgeons. UKAs comprised <10% of their knee arthroplasty practices, with an average of 14.2 medial UKAs per surgeon per year. Implant survival was assessed. Femoral coronal (FCA), femoral sagittal (FSA), tibial coronal (TCA), and tibial sagittal (TSA) angles as well as implant overhang were radiographically measured. Outliers were defined for FCA (>±10° deviation from neutral), FSA (>15° of flexion), TCA (>±5° deviation from neutral), and TSA (>±5° deviation from 7°). "Far outliers" were an additional >±2° of deviation. Outliers for overhang were identified as >3 mm for anterior overhang, >2 mm for posterior overhang, and >2 mm for medial overhang. RESULTS: Among patients with a failed UKA, revision was performed at an average of 3.7 years (range, 0.03 to 8.7 years). The cumulative revision rate was 14.2%. Kaplan-Meier survival analysis demonstrated 5 and 10-year survival rates of 88.0% (95% confidence interval [CI] = 82.0% to 91.0%) and 70.0% (95% CI = 56.0% to 80.0%), respectively. Only 19.0% (48) of the UKAs met target alignment for all 4 alignment measures, and only 72.7% (184) met all 3 targets for overhang. Only 11.9% (30) fell within all alignment and overhang targets. The risk of implant failure was significantly impacted by outliers for FCA (failure rate = 15.4%, p = 0.036), FSA (16.2%, p = 0.028), TCA (17.9%, p = 0.020), and TSA (15.2%, p = 0.034) compared with implants with no alignment or overhang errors (0%); this was also true for far outliers (p < 0.05). Other risk factors for failure were posterior overhang (failure rate = 25.0%, p = 0.006) and medial overhang (38.2%, p < 0.001); anterior overhang was not a significant risk factor (10.0%, p = 0.090). CONCLUSIONS: The proportions of UKA revisions and alignment outliers were greater than expected, even among high-volume arthroplasty surgeons performing an average of 14.2 UKAs per year (just below the high-volume UKA threshold of 15). Alignment and overhang outliers were significant risk factors for implant failure. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Local delivery of tobramycin and vancomycin in primary total knee arthroplasty achieves minimum inhibitory concentrations for common bacteria causing acute prosthetic joint infection.

AIMS: The aim of this study was to determine if the local delivery of vancomycin and tobramycin in primary total knee arthroplasty (TKA) can achieve intra-articular concentrations exceeding the minimum inhibitory concentration thresholds for bacteria causing acute prosthetic joint infection (PJI). METHODS: Using a retrospective single-institution database of all primary TKAs performed between January 1 2014 and May 7 2019, we identified patients with acute PJI that were managed surgically within 90 days of the initial procedure. The organisms from positive cultures obtained at the time of revision were tested for susceptibility to gentamicin, tobramycin, and vancomycin. A prospective study was then performed to determine the intra-articular antibiotic concentration on postoperative day one after primary TKA using one of five local antibiotic delivery strategies with tobramycin and/or vancomycin mixed into the polymethylmethacrylate (PMMA) or vancomycin powder. RESULTS: A total of 19 patients with acute PJI after TKA were identified and 29 unique bacterial isolates were recovered. The mean time to revision was 37 days (6 to 84). Nine isolates (31%) were resistant to gentamicin, ten (34%) were resistant to tobramycin, and seven (24%) were resistant to vancomycin. Excluding one Fusobacterium nucleatum, which was resistant to all three antibiotics, all isolates resistant to tobramycin or gentamicin were susceptible to vancomycin and vice versa. Overall, 2.4 g of tobramycin hand-mixed into 80 g of PMMA and 1 g of intra-articular vancomycin powder consistently achieved concentrations above the minimum inhibitory concentrations of susceptible organisms. CONCLUSION: One-third of bacteria causing acute PJI after primary TKA were resistant to the aminoglycosides commonly mixed into PMMA, and one-quarter were resistant to vancomycin. With one exception, all bacteria resistant to tobramycin were susceptible to vancomycin and vice versa. Based on these results, the optimal cover for organisms causing most cases of acute PJI after TKA can be achieved with a combination of tobramycin mixed in antibiotic cement, and vancomycin powder. Cite this article: Bone Joint J 2020;102-B(6 Supple A):163-169.