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Background: Little is known about patients' postoperative week-by-week progress after undergoing posterior approach total hip arthroplasty (THA) with regard to pain, function, return to work, and driving. Purpose : We sought to evaluate a large cohort of patients undergoing posterior approach THA with modified posterior hip precautions to better understand the trajectory of recovery. Methods : Patients at a single institution undergoing primary posterior approach THA by fellowship-trained arthroplasty surgeons were prospectively enrolled. Patient functional status and early rehabilitation recovery milestones were evaluated preoperatively and each week postoperatively for 6 weeks. Results : Of 312 patients who responded to weekly questionnaires, there were varying response rates per question. At 1 week after surgery, 15% (39/256) of respondents had returned to work, increasing to 57% (129/225) at week 6. At 6 weeks, 77% of patients (174/225) had returned to driving; 25% (56/225) were taking pain medication (including prescription opioids or nonsteroidal anti-inflammatory drugs); and 15% (34/225) were using assistive devices (down from 91%, 78%, 56%, 35%, and 27% at weeks 1, 2, 3, 4, and 5, respectively). Average postoperative Hip dysfunction and Osteoarthritis Outcome Score for Joint Replacement and Lower Extremity Functional Scale scores were significantly higher than preoperative scores. Respondents reported significantly less pain at each week postoperatively than the previous week. Conclusion : These findings suggest that there may be an expected pathway for recovery after posterior THA using perioperative pain protocols, modified postoperative precautions, and physical therapy protocols to improve patient outcomes after THA, with most patients returning to normal at 4 weeks. Defining the expected recovery timeline may help surgeons in counseling patients preoperatively and guiding their recovery., Competing Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Seth A. Jerabek, MD, reports relationships with Stryker and Imagen Technologies. David J. Mayman, MD, reports relationships with Orthalign, Smith and Nephew, Stryker, Imagen, Wishbone, and MiCare Path. Mark P. Figgie, MD, reports relationships with WishBone, Lima, HS2, and the Knee Society nominating committee. Peter K. Sculco, MD, reports relationships with Lima Corporate, Zimmer Biomet, Intellijoint Surgical, Depuy Synthes, ATEC (Eos Imaging), Parvizi Surgical Innovation, and the AAHKS outreach committee and publications committee. The other authors declare no potential conflicts of interest., (© The Author(s) 2023.)

Background : When comparing functional outcomes of patients with unicompartmental knee arthroplasty (UKA) versus total knee arthroplasty (TKA), studies often report the UKA as the preferred procedure; however, recent improvements in the design of modern TKA implants have aimed at narrowing this gap. Purpose : We sought to compare the "feel" of modern TKA implants to that of UKA, using the Forgotten Joint Score (FJS), a validated patient-reported outcome measure. Methods : We performed a retrospective review of patients who underwent TKA and UKA at 2 institutions between 2014 and 2017. All UKA procedures were robotic arm-assisted with a single implant, "traditional TKAs" were performed using traditional posterior-stabilized implants, and "modern TKAs" were performed using posterior-stabilized implants with a modern design. Differences in FJS were assessed using 1-way analysis of variance and independent 2-sample t tests. Results : A total of 600 patients were included in our study, with 200 patients in each surgical subcategory. Mean age was 62.8 ± 10.2 years and mean body mass index was 29.9 ± 4.9. Modern TKA and UKA had similar FJS at 1 year. While modern TKA had a significantly higher FJS than traditional TKA, UKA did not have a significantly higher FJS than traditional TKA. Conclusion : Our retrospective analysis found no significant differences in the FJS of patients who underwent UKA and TKA with a modern design; however, both had superior scores than traditional TKA designs. This finding suggests that modern TKA designs may have the potential to achieve the natural feeling that is typically associated with joint-conserving surgeries such as UKA, although longer follow-up is necessary., Competing Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Michael P. Ast, MD, reports relationships with Smith and Nephew and Orthalign. David J. Mayman, MD, reports relationships with Orthalign, Imagen, Smith and Nephew, and Wishbone. Andrew D. Pearle, MD, reports relationships with Smith and Nephew, Engage, and Stryker. Alvin C. Ong, MD, reports relationships with Smith and Nephew and Stryker. The other authors report no potential conflicts of interest., (© The Author(s) 2022.)

Background: Spinopelvic hypermobility may be secondary to a stiff osteoarthritic hip with a compliant spine. Purpose: We sought to determine if spinopelvic hypermobility resolves after total hip arthroplasty (THA) and when it resolves in patients with bilateral hip osteoarthritis (OA) undergoing staged bilateral THA. We also sought to analyze the change in spinopelvic parameters before and after the second THA. Methods: We conducted a retrospective review of 2047 THAs that were performed by 2 fellowship-trained arthroplasty surgeons from 2014 to 2018. Patients with preoperative spinopelvic hypermobility undergoing staged bilateral THA were identified. Radiographic spinopelvic parameters, including sacral slope (SS), pelvic incidence (PI), lumbar lordosis (LL), PI-LL mismatch, anterior pelvic plane tilt (APPt), and spinopelvic tilt (SPT), were measured on preoperative, 6-week postoperative, and 1-year postoperative lateral standing and sitting radiographs. Bilateral hip OA was graded using Kellgren-Lawrence criteria. Results: We identified 42 patients with preoperative spinopelvic hypermobility who underwent staged bilateral THA. Mean time (standard deviation) between surgeries was 9.4 months (±10.0). After the first THA, spinopelvic hypermobility resolved in 29% of the patients. After the second THA, it resolved in 67% at 6 weeks, increasing to 98% at 1 year postoperatively. Conclusion: Spinopelvic hypermobility resolves after staged bilateral THA in 98% of the patients, occurring most often only after the second THA. Less than one-third of the patients had resolution after the first THA, suggesting that contralateral hip OA continues to drive hip-driven spinopelvic motion. Acetabular component position targets based on functional pelvic position should incorporate these changes in spinopelvic motion with the understanding that resolution of hypermobility usually occurs after the second THA., Competing Interests: Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Eric N. Windsor, MS, declares he has nothing to disclose. Peter K. Sculco, MD, reports relationships with Intellijoint Surgical, Depuy Synthes, and EOS Imaging outside the submitted work. David J. Mayman, MD, reports relationships with Imagen, Insight, Orthalign, Wishbone, and Smith and Nephew outside the submitted work. Jonathan M. Vigdorchik, MD, reports relationships with Corin, Intellijoint Surgical, Medacta, Motion Insights, and Zimmer outside the submitted work. Seth A. Jerabek, MD, reports relationships with Imagen and Stryker outside the submitted work., (© The Author(s) 2021.)

Background: Success of treatment for hip or knee osteoarthritis (OA) should be evaluated relative to patients' personal activity goals. Questions/Purposes : We sought to ascertain important principles for collecting such goals and developed a survey informed by those principles to facilitate better shared decision-making. Methods : From a series of 100 patient interviews inquiring about specific activity goals, we identified 6 principles for goal collection that are important to patients and physicians and could practically facilitate better shared decision-making (phase 1). Incorporating these principles, we designed a self-administered survey to measure specific pretreatment activity goals, piloting in 1 surgeon's office (phase 2). During office visits, the feasibility of achieving stated goals was discussed between the surgeon and the patient, and goal modifications were recorded. Results : The phase 2 survey was administered to 252 patients, among whom 130 were women (51.6%); 215 (85.3%), white; mean age, 58.5 years; mean body mass index, 30.2 kg/m 2 ; and 92.9% had 1 or more goals, totaling 106 unique goals. Patient demographics were associated with having goals for walking, running, exercising, golfing, tennis, and stairs. Hip and knee patients could last perform their goal on average 21.7 and 38.6 months prior ( P = .002). Patient and surgeon agreed to modify goals 19% of the time, more often among younger patients ( P = .001) and for running (64% modified, P < .0001) and skiing (42%, P = .0026), but less often for walking (14%, P = .0430) and golf (0%, P = .0204). Conclusions : Patients' activity goals can be captured by a self-administered survey, collected before an office visit, and used to facilitate shared decision-making., Competing Interests: Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: MLP reports relationships with Zimmer Biomet, the Orthopedic Research and Education Foundation (OREF), and the American Academy of Orthopedic Surgeons (AAOS). DJM reports relationships with Smith & Nephew, Stryker, Cymedica, HS2, Insight Global, Evolve Ortho, Imagen, and Orthalign. MAF, WI, MAR, and CHM report no potential conflicts of interest., (© The Author(s) 2022.)

Background: The interest in ambulatory total hip arthroplasty (THA) has increased recently due to a national focus on value-based care and improved rapid recovery protocols. Purpose: We sought to determine if surgical approach had an effect on discharge outcomes in outpatient THA. Methods: We performed a retrospective cohort study examining patients who underwent unilateral THA at a single institution using a standardized perioperative care pathway who were discharged home within 24 hours. In total, we compared 106 patients who underwent THA using the direct anterior approach (ATHA) and 90 patients who underwent THA using the posterior approach (PTHA). Univariate and multivariable analyses were used to compare time to ambulation, length of surgery, readmissions, and 90-day complications. Results: Time to ambulation in the ATHA and PTHA groups was 3.9 hours and 4.1 hours, respectively, and time to discharge was 5.9 hours and 6.0 hours, respectively. Length of surgery was shorter in the ATHA group than in the PTHA group (78 minutes vs 86 minutes, respectively). Complications occurred in 3 patients (3%) in the ATHA group vs 4 patients (4%) in PTHA group. In both groups, early ambulation (within 5 hours) predicted earlier time to discharge. Surgical approach was not associated with time to ambulation or time to discharge on multivariable analysis. Conclusion: In this retrospective study, outpatient THA was feasible in a well-selected population of patients undergoing anterior or posterior approaches. Further study is warranted., Competing Interests: Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Bradford S. Waddell, MD, and Michael P. Ast, MD, both report relationships with Surgical Care Associates, Eastern Orthopaedic Association (EOA), American Association of Hip and Knee Surgeons (AAHKS), and American Academy of Orthopaedic Surgeons (AAOS), outside the submitted work. David J. Mayman, MD, reports relationships with CyMedica Orthopedics, Evolve Ortho LLC, HS2, Imagen Technologies, InSight Medical, OrthAlign, Smith & Nephew, Stryker-Consulting, and Wishbone, outside the submitted work. Seth A. Jerabek, MD, reports relationships with Imagen and Stryker outside the submitted work. Michael M. Alexiades, MD, reports relationships with DePuy and DJO outside the submitted work. Drake G. LeBrun, MD, MPH, and Scott M. LaValva, MD, declare they have no potential conflicts of interest., (© The Author(s) 2021.)

Background : There is little data on the magnitude and factors for functional leg lengthening after primary total knee arthroplasty (TKA). Questions/Purpose : We sought to determine the incidence of and risk factors for functional leg lengthening after primary TKA. Methods : We retrospectively reviewed consecutive unilateral primary TKAs at a single institution from 2015 to 2018. Of the 782 TKAs included, 430 (55%) were performed in women; the mean age was 66 years, and the mean body mass index was 29 kg/m 2 . Preoperatively, 541 (69%) knees were varus deformities and 223 (29%) were valgus deformities. Hip to ankle biplanar radiographs were obtained preoperatively and 6 weeks postoperatively for all patients. Two independent researchers measured leg length, coronal plane deformity, lateral knee flexion angle, and overall mechanical alignment on all preoperative and postoperative radiographs. Results : The mean overall ipsilateral functional leg lengthening was 7.0 mm. Seven hundred knees (90%) were overall functionally lengthened, including 462 (59%) knees lengthened >5 mm and 250 (31%) knees lengthened 10 mm or more. A valgus deformity and coronal plane deformity of 10° or more were significant risk factors for increased functional lengthening. Patients with severe valgus deformities (>10°) had the largest amount of functional lengthening, at a mean of 13.5 mm. Conclusion : After primary TKA, 90% of limbs are functionally lengthened, including roughly one-third over a centimeter. Valgus knee deformities and severe deformities (>10°) were significant risk factors for increased limb lengthening., Competing Interests: Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Peter K. Sculco, MD, reports relationships with DePuy, EOS Imaging, Intellijoint Surgical, and Lima Corporate, outside the submitted work. Steve B. Haas, MD, reports relationships with Smith & Nephew, OrthoAlign, Heraeus, and Ortho. Secure, outside the submitted work. David J. Mayman, MD, reports relationships with Imagen, Smith & Nephew, OrthAlign, Insight, and Wishbone, outside the submitted work. The other authors report no potential conflicts of interest., (© The Author(s) 2021.)

Background : Robotic-assisted total knee arthroplasty (rTKA) has emerged as a patient-specific customizable tool that enables 3-dimensional preoperative planning, intraoperative adjustment, robotic-assisted bone preparation, and soft-tissue protection. Haptic rTKA may enhance component positioning, but only a few small studies have examined patient satisfaction and clinical outcomes after haptic rTKA. Purpose : In patients who underwent haptic rTKA, we sought to evaluate (1) the discrepancy in alignment between the executed surgical plan and implanted alignment in the coronal and sagittal planes 1 year postoperatively and (2) patient-reported outcomes 2 years postoperatively. Methods : From a prospectively collected database, we reviewed 105 patients who underwent haptic rTKA from August 2016 to May 2017. Two fellowship-trained arthroplasty surgeons independently reviewed hip-to-ankle standing biplanar radiographs to measure overall limb alignment and individual tibial and femoral component alignment relative to the mechanical axis and compared this to the executed surgical plan. Patient-reported outcomes were collected preoperatively and at 2 years postoperatively using the Lower Activity Extremity Score (LEAS), Knee Injury and Osteoarthritis Outcome Score Junior (KOOS Jr.), and Numeric Pain Rating Scale (NPRS). Results : Mean patient age was 62.4 years, and mean body mass index was 30.6 kg/m 2 . Interobserver reliability was significant with a κ of 0.89. Absolute mean deviations in postoperative coronal alignment compared to intraoperative alignment were 0.625° ± 0.70° and 0.45° ± 0.50° for the tibia and femur, respectively. Absolute mean deviations in postoperative tibial sagittal alignment were 0.47° ± 0.76°. Overall mechanical alignment was 0.97° ± 1.79°. Outcomes in LEAS, KOOS Jr., and NPRS changed from 8 to 10, 78 to 88.3, and 8 to 1, respectively. Conclusions : Haptic rTKA demonstrated high reliability and accuracy (less than 1°) of tibial coronal, femoral coronal, and tibial sagittal component alignment postoperatively compared to the surgical plan. Patient-reported outcomes improved, as well. A more rigorous study on long-term outcomes is warranted., Competing Interests: Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Kaitlin M. Carroll, BS, reports relationships with Canary Medical and Orthalign. Andrew D. Pearle, MD, reports relationships with Stryker, Exactech, Engage, Smith and Nephew, and Zimmer. David J. Mayman, MD, reports relationships with Stryker, Imagen, Insight, Smith and Nephew, and Wishbone. Geoffrey Westrich, MD, reports relationships with Stryker, Exactech, and Mallinckrodt Pharmaceuticals. Seth Jerabek, MD, reports relationships with Stryker and Imagen. Brian Nickel, MD, Laura J. Kleeblad, MD, and Joost Burger, DMed, declare no potential conflicts of interests., (© The Author(s) 2021.)

Background: The early months of the coronavirus disease 19 (COVID-19) pandemic in New York City led to a rapid transition of non-essential in-person health care, including outpatient arthroplasty visits, to a telemedicine context. Questions/Purposes: Based on our initial experiences with telemedicine in an outpatient arthroplasty setting, we sought to determine early lessons learned that may be applicable to other providers adopting or expanding telemedicine services. Methods: A cross-sectional study was performed by surveying all patients undergoing telemedicine visits with 8 arthroplasty surgeons at 1 orthopedic specialty hospital in New York City from April 8 to May 19, 2020. Descriptive statistics were used to analyze demographic data, satisfaction with the telemedicine visit, and positive and negative takeaways. Results: In all, 164 patients completed the survey. The most common reasons for the telemedicine visit were short-term (less than 6 months), postoperative appointment ( n = 88; 54%), and new patient consultation ( n = 32; 20%). A total of 84 patients (51%) noted a reduction in expenses versus standard outpatient care. Several positive themes emerged from patient feedback, including less anxiety and stress related to traveling ( n = 82; 50%), feeling more at ease in a familiar environment ( n = 54; 33%), and the ability to assess postoperative home environment ( n = 13; 8%). However, patients also expressed concerns about the difficulty addressing symptoms in the absence of an in-person examination ( n = 28; 17%), a decreased sense of interpersonal connection with the physician ( n = 20; 12%), and technical difficulties ( n = 14; 9%). Conclusions: Patients were satisfied with their telemedicine experience during the COVID-19 pandemic; however, we identified several areas amenable to improvement. Further study is warranted., Competing Interests: Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Drake G. LeBrun, MD, MPH, Christina Malfer, BA, Mallory Wilson, BA, Kaitlin M. Carroll, BA, and Victoria Wang declare that they have no conflicts of interest. David J. Mayman, MD, reports stock or stock options from Imagen, Wishbone, and Insight; stock or stock options and royalties from Orthalign; and personal fees, royalties, and research support from Smith and Nephew, outside the submitted work. Michael B. Cross, MD, reports personal fees from Depuy, Smith and Nephew, and Flexion Therapeutics; personal fees and research support from Exactech; personal fees and stock or stock options from Imagen; personal fees, research support, and stock or stock options from Intellijoint; personal fees and research support from KCI; and stock or stock options from Parvizi Surgical Innovation, outside the submitted work. Michael M. Alexiades, MD, reports personal fees and royalties from DJ Orthopedics, outside the submitted work. Seth A. Jerabek, MD, reports stock or stock options from Imagen, personal fees and research support from Stryker, outside the submitted work. Fred D. Cushner, MD, reports personal fees from Acelity and Smith and Nephew, stock or stock options from Canary Medical, personal fees and stock or stock options from Orthalign, outside the submitted work. Jonathan M. Vigdorchik, MD, reports personal fees and research support from Corin, personal fees and stock or stock options from Intellijoint, and personal fees from Medacta, Motion Insights, and Zimmer, outside the submitted work. Steven B. Haas, MD, reports personal fees from Smith and Nephew, outside the submitted work. Michael P. Ast, MD, reports personal fees from Conformis, Stryker, and Surgical Care Affiliates; personal fees, stock or stock options, and royalties from Orthalign; stock or stock options from OSSO VR; and personal fees and research support from Smith and Nephew, outside the submitted work., (© The Author(s) 2020.)

Background: Surgical treatment options for addressing recurrent dislocation after total hip arthroplasty (THA) vary. Identifying impingement mechanisms in an unstable THA may be beneficial in determining appropriate treatment., Questions/purposes: We sought to assess the effectiveness of developing pre-operative plans for treating hip instability after THA. We used advanced imaging and three-dimensional modeling techniques to perform impingement analyses in patients with unstable THA., Methods: We evaluated a series of eight patients who would require revision THA to treat recurrent dislocation. Using a pre-operative algorithmic approach, we built patient-specific models and evaluated hip range of motion with computed tomographic scanning and biplanar radiography. This information was used to determine a surgical treatment plan that was then executed intra-operatively. Patients were followed for 2 years to determine whether they experienced another hip dislocation following treatment., Results: Pre-operative kinematic modeling showed four of the eight patients had limited hip range of motion during flexion and internal rotation; a prominent anterior inferior iliac spine (AIIS) was found to limit hip range of motion in some of these cases. In the other four patients, range of motion was acceptable, suggesting soft-tissue causes of dislocation. No patients in this series experienced dislocation after undergoing revision THA., Conclusion: Advanced modeling techniques may be useful for identifying the impingement mechanisms responsible for instability after THA. Once variables contributing to limited hip range of motion are identified, surgeons can develop treatment plans to improve patient outcomes. Resecting a hypertrophic AIIS may improve hip range of motion and may be an important consideration for hip surgeons when revising unstable THAs., Competing Interests: Conflict of InterestSean A. Sutphen, DO, and Christina I. Esposito, PhD, declare that they have no conflicts of interest. Joseph D. Lipman, MS, reports royalties from Exactech, Inc., Lima Corporate, Mathys Ltd., and Ortho Development Corporation, outside the submitted work. Seth A. Jerabek, MD, reports personal fees, royalties, and grants from Stryker and stock or stock options from Imagen Technologies, outside the submitted work. David J. Mayman, MD, reports personal fees and grants from Smith & Nephew, stock or stock options from Imagen Technologies and OrthAlign, and board membership in the Knee Society, outside the submitted work., (© The Author(s) 2019.)

Background: Acetabular component position alone has not been predictive of stability after total hip arthroplasty (THA). Combined anteversion of the acetabulum and femur has the potential of being more predictive of stability. Unfortunately, femoral component position is difficult to measure on plain radiographs. Computed tomography (CT) is the gold standard for measuring implant position post-operatively, but CT exposes patients to a substantial amount of radiation., Questions/purposes: We sought to determine whether biplanar low-dose radiography can be used to accurately measure both acetabular and femoral implant position after THA., Methods: Twenty patients underwent standing low-dose biplanar spine-to-ankle radiographs and supine CT scans 6 weeks after THA. Measurements of acetabular inclination, acetabular anteversion, and femoral anteversion were performed by two blinded observers and compared., Results: The average absolute differences between biplanar radiographs and CT scans were 2° ± 2° for acetabular inclination, 3° ± 2° for acetabular anteversion, and 4° ± 4° for femoral anteversion between EOS measurements and CT measurements. Interobserver agreement was good for acetabular inclination, acetabular anteversion, and femoral anteversion (Cronbach's α  = 0.90) using biplanar low-dose imaging., Conclusion: Biplanar radiography is a reliable low-radiation alternative for measuring acetabular inclination, acetabular anteversion, femoral version, and thus combined anteversion compared to CT. Femoral anteversion had the most variability but is still clinically relevant., Competing Interests: Conflict of InterestChristina I. Esposito, PhD, and Kaitlin M. Carroll, BS, declare that they have no conflicts of interest. David J. Mayman, MD, reports stock or stock options from Imagen Technologies and OrthAlign; personal fees for consultancy, lectures, and grants from Smith & Nephew; and board membership with the Knee Society. Douglas E. Padgett, MD, reports board membership with American Joint Replacement Registry, Journal of Arthroplasty, and Hip Society; personal fees and royalties from DJ Orthopaedics and PixarBio; and stock or stock options from PixarBio. Joseph D. Lipman, MS, reports royalties from Exactech, Inc., LimaCorporate, Mathys Ltd., and Ortho Development Corporation. Seth A. Jerabek, MD, reports personal fees, speakers’ fees, royalties, and grants from Stryker and stock and stock options from Imagen Technologies. Theodore T. Miller, MD, reports educational fees from Amirsys Publishing Co., (© Hospital for Special Surgery 2019.)

Background: Post-operative rehabilitation after posterior-approach total hip arthroplasty (P-THA) includes the use of standard hip precautions, defined as no hip flexion beyond 90°, hip adduction, or hip internal rotation for 6 to 12 weeks after surgery (sometimes for life). Since they were first implemented in the 1970s, subsequent advances may have made standard hip precautions no longer necessary, although little evidence supports that hypothesis. A modified set of precautions, a "pose avoidance protocol," could be effective in enhancing recovery, but its effectiveness on early dislocation and post-surgical outcomes is not known., Questions/purposes: We sought to determine the functional recovery of patients on a pose avoidance protocol after P-THA according to levels of pain and patient satisfaction, rates of dislocation, the use of assistive devices, and a return to driving., Methods: We conducted a retrospective, descriptive study of data from a consecutive case series of 164 patients treated by a single surgeon between January 2014 and December 2015. Patients who had undergone a primary uncemented P-THA were prescribed a pose avoidance protocol and followed for a minimum of 6 weeks. Exclusion criteria were patients with congenital hip dysplasia, revision THA, femoral neck fracture, rheumatoid arthritis, or neuromuscular disease. Changes to the rehabilitation protocol included elimination of the requirements to use elevated chairs, raised toilet seats, and abduction pillows for sleeping. Patients could resume driving at 2 and 3 weeks for left and right P-THA, respectively. The only motion restriction was avoiding the combination of hip flexion past 90°, hip adduction, and hip internal rotation. Patients could perform all other movements and to bear weight and stop using walking aids as tolerated. Patients completed a biweekly questionnaire to assess their functional recovery, opioid use, and pain levels., Results: At 2 weeks after surgery, 80% of patients reported no pain, 86% did not require walking aids, and 92% were satisfied with their recovery. At 6 weeks after surgery, 89% of patients reported no pain. Patients returned to driving at a mean of 2.7 weeks after surgery. No patients had experienced a dislocation at 6 weeks of follow-up., Conclusion: A pose avoidance rehabilitation protocol in this P-THA population was found to be safe and was associated with accelerated functional recovery and high patient satisfaction without increased risk of early post-operative dislocation., Competing Interests: Conflict of InterestErica Fritz Eannucci, PT, DPT, OCS, Brian T. Barlow, MD, and Kaitlin M. Carroll, BS, declare that they have no conflicts of interest. Seth A. Jerabek, MD, reports personal fees and royalties from Stryker, outside the submitted work. Peter K. Sculco, MD, reports personal fees from Intellijoint, outside the submitted work. David J. Mayman, MD, reports personal fees and research support from Smith & Nephew and stock or stock options from Imagen and OrthAlign, outside the submitted work., (© Hospital for Special Surgery 2019.)

Background: Proper alignment of total knee arthroplasty (TKA) is essential for TKA function and may reduce the risk of aseptic failure. Technologies that prevent malalignment may reduce the risk of revision surgery., Questions/purposes: The purpose of this study was to compare two competing TKA systems that purport improved alignment: patient-specific instrumentation (PSI), and a handheld portable navigation device (NAV)., Methods: After IRB approval, 49 consecutive PSI TKAs (40 patients) were matched based on preoperative characteristics to 49 NAV TKAs (40 patients) performed by a single surgeon. A blinded observer measured alignment on digital radiographs. Operating room records were reviewed for procedure times. Two-tailed paired sample t tests and McNemar's test were used as appropriate. Alpha level was 0.05 for all tests., Results: Preoperative cohort characteristics were not different. Mean postoperative long-leg mechanical alignment was within ±1° of neutral for both groups, although statistically different ( p  = 0.026). There were no other significant differences in coronal alignment. PSI exhibited significantly greater posterior tibial slope (4.4°) compared to NAV (2.7°) ( p  = 0.004); PSI resulted in significantly more outliers (>6°; p  = 0.004). Procedure time for unilateral TKAs was lower for PSI (74.4 min) compared to that for NAV (80.6 min; p  = 0.023)., Conclusion: NAV and PSI technologies provided excellent coronal plane alignment. NAV was better for sagittal tibial slope, while PSI procedure times were shorter for unilateral TKA. The impact of these technologies on patient-reported outcomes and TKA survivorship is controversial and should be the focus of future research.

Background: Measuring acetabular anteversion is relevant to routine follow-up of total hip arthroplasties (THAs) and for malfunctioning THAs. Imageless navigation facilitates acetabular component orientation relative to the anterior pelvic plane (APP) or to the APP adjusted for sagittal pelvic tilt (PT). The optimal plain radiographic method for the postoperative assessment of anteversion is not agreed upon., Questions/purposes: (1) Do anteversion measurements on plain radiographs correlate more with APP anteversion or PT-adjusted anteversion? (2) Do measurements of anteversion performed on supine anteroposterior (AP) radiographs more accurately reflect intraoperative anteversion values for navigated THA compared to anteversion measured on cross-table lateral (CL) radiographs?, Methods: Seventy patients receiving primary navigated THA were included. APP and PT-adjusted anteversion were recorded; the latter defined the intraoperative target for anteversion. Postoperative anteversion was measured on supine AP pelvis radiographs with computer software and CL radiographs with conventional methods. Intraoperative measurements were used as the reference standards for comparisons., Results: Mean intraoperative APP anteversion was 20.6° ± 5.6°. Mean intraoperative PT-adjusted anteversion was 22.9° ± 4.5°. Mean anteversion was 22.7° ± 4.7° on AP radiographs and 27.2° ± 4.2° on CL radiographs (p < 0.001). Only correlations between PT-adjusted anteversion and radiographic assessments of anteversion were significant. The mean difference between PT-adjusted anteversion and anteversion on AP radiographs was -0.2° ± 4.3°, while the mean difference between the PT-adjusted anteversion and anteversion measured on CL radiographs was 4.3 ± 5.1° (p < 0.001)., Conclusion: Plain film assessment of anteversion was more accurate on supine AP radiographs than on CL radiographs, which overestimated acetabular anteversion.

Background: Over the last several years, a trend towards increasing femoral head size in total hip arthroplasty to improve stability and impingement free range of motion has been observed., Purpose: The specific questions we sought to answer in our review were: (1) What are the potential advantages and disadvantages of metal-on-metal, ceramic-on-ceramic, and metal-on-polyethylene bearings? (2) What is effect that femoral head size has on joint kinematics? (3) What is the effect that large femoral heads have on bearing surface wear?, Methods: A PubMed search and a review of 2012 Orthopaedic Research Society abstracts was performed and articles were chosen that directly answered components of the specific aims and that reported outcomes with contemporary implant designs or materials., Results: A review of the literature suggests that increasing femoral head size decreases the risk of postoperative dislocation and improves impingement free range of motion; however, volumetric wear increases with large femoral heads on polyethylene and increases corrosion of the stem in large metal-on-metal modular total hip arthroplasty (THA); however, the risk of potentially developing osteolysis or adverse reactions to metal debris respectively is still unknown. Further, the effect of large femoral heads with ceramic-on-ceramic THA is unclear, due to limited availability and published data., Conclusions: Surgeons must balance the benefits of larger head size with the increased risk of volumetric wear when determining the appropriate head size for a given patient.