Does a Uni "Feel Better" than a Total Knee? Not Necessarily, When Using Modern Implant Designs.

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.

Carboplasty, a Simple Tibial Marrow Technique for Knee Osteoarthritis: A Placebo-Controlled Randomized Trial.

Background: Carboplasty is a new minimally invasive technique for knee osteoarthritis (OA) that consists of injecting tibial marrow aspirate into the bone-cartilage interface as well as intra-articularly. Purpose: To compare the clinical and imaging outcomes, as well as the safety, of carboplasty for symptomatic knee OA in a placebo-controlled trial. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: The authors conducted a randomized controlled trial to compare carboplasty with placebo for the treatment of symptomatic knee OA. Patients who had failed medical treatment and had bone edema on magnetic resonance imaging (MRI) were randomized in a 1:1 ratio to carboplasty or placebo. The primary outcome of the study was the Numeric Pain Rating Scale (NPRS) for the knee at 1 year (scores range from 0 to 10, with a higher score indicating worse pain). Secondary outcomes were the Knee injury and Osteoarthritis Outcome Score (KOOS), treatment responder rate (based on achieving the minimal clinically important difference of the NPRS), MRI bone edema reduction, and treatment safety. Results: In total, 50 patients (25 carboplasty vs 25 placebo) were enrolled and followed up with for an average of 18 months (range, 14-24 months). The average NPRS at baseline decreased from 7.1 ± 0.9 to 2.9 ± 2.1 (P < .001) at 1 year in the carboplasty group and from 7.7 ± 0.9 to 4.9 ± 2.2 (P < .001) in the placebo group. On average, patients after carboplasty improved 60% from their initial NPRS, and patients after placebo improved 37% (P = .003). Patients had a statistically significantly greater improvement from baseline in all KOOS subscales in the carboplasty group compared with the placebo group (P < .001). The responder rates were 96% for carboplasty and 76% for placebo (P = .098). Bone edema was reduced in 72% of patients in the carboplasty group and 44% of patients in the placebo group (P = .045). Neither group had adverse events related to treatment. Conclusion: Carboplasty resulted in greater pain reduction, a significantly greater improvement in all KOOS subscales, and a similar safety profile compared with placebo in patients with symptomatic knee OA and bone edema. Registration: ISRCTN69838191 (ISRCT Registry).

"Back Rx, a personalized mobile phone application for discogenic chronic low back pain: a prospective pilot study".

BACKGROUND: Intervertebral disc pathology is the most common identifiable cause of chronic lower back pain (CLBP). There are limited conservative alternatives to treat discogenic axial CLBP. Back Rx is a mobile application (app) developed to treat patients with this condition, following the Back Rx exercise program, assisted by a virtual coach. METHODS: Patients 18 to 65 years of age, with axial CLBP (more than 3 months), and evidence of lumbar disc pathology by magnetic resonance imaging (MRI) were enrolled to the study. Patients' symptomatology was prospectively evaluated at baseline and after 3 months of using the Back Rx app. The main outcome of the study was back pain evaluated using the visual analog scale (VAS) for pain. Secondary outcomes were the patient's functionality, the weekly pain medication intake, the patients' adherence to the app, and the patients´ satisfaction rate. RESULTS: Seventy-five patients with CLBP were enrolled in the study. All patients had a statistically significant improvement from baseline to final follow-up in the average VAS scores, and the functionality evaluations. Average VAS scores decreased from 5.17 ± 2.1 at baseline to 3.8 ± 2.6 at final follow-up (P = 0.016). Patients showed a significant decrease in the number of pain medications taken during a week (P = 0.001). Overall compliance with the app was 52%, and 65% of the patients rated the overall experience as good or excellent. CONCLUSION: The Back Rx app decreased pain and increased function in patients with discogenic axial CLBP compared to their baseline status. Further measures are needed to increase patients' compliance with the app and the Back Rx program. TRIAL REGISTRATION: Retrospectively registered in 2/2/2017 NCT03040310 (ClinicalTrials.gov).

Do obese patients benefit from a kinematic, appropriately designed total knee prosthesis?

Introduction: Modern total knee arthroplasty (TKA) using the Journey 2 implant utilizes a bicruciate stabilized (BCS) technique. However, whether bicruciate stabilized TKA is equally effective across weight classes is unknown. Methods: We identified patients who underwent primary bicruciate stabilized TKA during 2016 and 2017, at a single institution. All included patients had, at minimum, 2-year follow-up. Patients were categorized into body-mass index (BMI) groups as follows: underweight, normal, or overweight (<30 kg/m2), obese (≥30 to <35 kg/m2), and severely obese (≥35 kg/m2). Patient reported outcome measures (PROMs) were measured at baseline. Both KSS and KOOS JR, along with the Visual Analogue Scale (VAS), were also recorded at follow-up. Pre-operative, post-operative, and pre-to post-operative changes in PROMs were analyzed using analysis of variance (ANOVA) and linear regression. Results: The 292 patients had a mean age of 64.8 years and mean BMI of 32.3 kg/m2. There were 116 (39.7%) patients in the underweight, normal, or overweight group, 88 (30.1%) in the obese category, and 88 (30.1%) in the severely obese group. There were no differences between PROMs at baseline or at follow-up (p > 0.10 for all comparisons). There were also no differences in the improvement from pre-to post-operative KSS (p = 0.21) and KOOS JR (p = 0.62). Conclusions: Bicruciate stabilized TKA has similar effects on PROMs across BMI groups. These results suggest that bicruciate stabilized TKA is a viable treatment option both for low-weight and high-weight patients.

Computer Navigation for Revision Total Hip Arthroplasty Reduces Dislocation Rates.

Purpose: Computer navigation in total hip arthroplasty (THA) offers potential for more accurate placement of acetabular components, avoiding impingement, edge loading, and dislocation, all of which can necessitate revision THA (rTHA). Therefore, the use of computer navigation may be particularly beneficial in patients undergoing rTHA. The purpose of this study was to determine if the use of computer-assisted hip navigation reduces the rate of dislocation in patients undergoing rTHA. Methods: A retrospective review of 72 patients undergoing computer-navigated rTHA between February 2016 and May 2017 was performed. Demographics, indications for revision, type of procedure performed, and incidence of postoperative dislocation were collected for all patients. Clinical follow-up was recorded at 3 months, 1 year and 2 years. Results: All 72 patients (48% female; 52% male) were included for analysis. The mean age was 70.4 ± 11.2 years and mean BMI was 26.4 ± 5.2 kg/m2. 22 of 72 patients (31%) required a rTHA procedure due to instability resulting in dislocation. At 3 months, 1 year, and 2 years, there were no dislocations (0%). There was a significant reduction in dislocation rate after computer-navigated rTHA (0%) relative to that following primary THA in the same patient cohort (31%; p < 0.05). Conclusion: Our study demonstrates a significant reduction in dislocation rate following rTHA with computer navigation. Although the cause of postoperative dislocation is often multifactorial, the use of computer navigation may help to curtail femoral and acetabular malalignment in rTHA. Level of Evidence: Level III: retrospective.

Does Low Back Pain Improve Following Total Hip Arthroplasty?

BACKGROUND: Frequently, patients indicated for total hip arthroplasty (THA) present with low back pain (LBP) and hip pain. The purpose of this study was to compare patients whose back pain resolved after THA with those where back pain did not resolve and identify how to predict this using spinopelvic parameters. METHODS: We reviewed a series of 500 patients who underwent THA for unilateral hip osteoarthritis by 2 surgeons. Patients underwent biplanar standing and sitting EOS radiographs pre-operatively. Patients with previous spine surgery or femoral neck fracture were excluded. Demographic data was analyzed at baseline. The Oswestry Disability Index (ODI) scores were calculated pre-operatively and at 1 year postoperatively. Spinopelvic parameters included, pelvic incidence and sacral slope (SS) change from standing to sitting. RESULTS: Two hundred and four patients (41%) had documented LBP before THA. The Oswestry Disability Index (ODI) for patients improved from 38.9 ± 17.8 pre-operatively to 17.0 ± 10.6 at 1 year post-operatively (P < .001). At 1- and 2-year follow-up, resolution of back pain occurred in 168 (82.4%) and 187 (91.2%) patients, respectively. Pelvic incidence was not predictive of back pain resolution. All patients whose back pain resolved had a sacral slope change from standing to sitting of >10°, while those patients whose back pain did not resolve had a change of <10°. CONCLUSION: This study demonstrates that symptomatic low back pain (LBP) resolves in 82% of patients after THA. The results of this study may be used to counsel patients on back pain and its resolution following total hip replacement.

The Accuracy and Clinical Success of Robotic-Assisted Total Knee Arthroplasty.

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/m2. 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.

2021 Otto Aufranc Award: A simple Hip-Spine Classification for total hip arthroplasty : validation and a large multicentre series.

AIMS: Patients with spinal pathology who undergo total hip arthroplasty (THA) have an increased risk of dislocation and revision. The aim of this study was to determine if the use of the Hip-Spine Classification system in these patients would result in a decreased rate of postoperative dislocation in patients with spinal pathology. METHODS: This prospective, multicentre study evaluated 3,777 consecutive patients undergoing THA by three surgeons, between January 2014 and December 2019. They were categorized using The Hip-Spine Classification system: group 1 with normal spinal alignment; group 2 with a flatback deformity, group 2A with normal spinal mobility, and group 2B with a stiff spine. Flatback deformity was defined by a pelvic incidence minus lumbar lordosis of > 10°, and spinal stiffness was defined by < 10° change in sacral slope from standing to seated. Each category determined a patient-specific component positioning. Survivorship free of dislocation was recorded and spinopelvic measurements were compared for reliability using intraclass correlation coefficient. RESULTS: A total of 2,081 patients met the inclusion criteria. There were 987 group 1A, 232 group 1B, 715 group 2A, and 147 group 2B patients. A total of 70 patients had a lumbar fusion, most had L4-5 (16; 23%) or L4-S1 (12; 17%) fusions; 51 patients (73%) had one or two levels fused, and 19 (27%) had > three levels fused. Dual mobility (DM) components were used in 166 patients (8%), including all of those in group 2B and with > three level fusions. Survivorship free of dislocation at five years was 99.2% with a 0.8% dislocation rate. The correlation coefficient was 0.83 (95% confidence interval 0.89 to 0.91). CONCLUSION: This is the largest series in the literature evaluating the relationship between hip-spine pathology and dislocation after THA, and guiding appropriate treatment. The Hip-Spine Classification system allows surgeons to make appropriate evaluations preoperatively, and it guides the use of DM components in patients with spinopelvic pathology in order to reduce the risk of dislocation in these high-risk patients. Cite this article: Bone Joint J 2021;103-B(7 Supple B):17-24.

Perspective of Attending Physicians on the Use of Telemedicine in an Outpatient Arthroplasty Setting During the COVID-19 Pandemic.

Background: During the worldwide COVID-19 pandemic, physicians had to improvise and adapt new ways to provide care to patients. Purposes: The purpose of this study was to assess physicians' sentiments regarding telemedicine and its use in orthopedic practices. Methods: We performed a cross-sectional study of attending orthopedic physicians, the majority of whom integrated telemedicine into their practices from March to October 2020. A survey was sent to 517 physicians who had registered for an orthopedics conference. The survey included questions pertaining to various factors regarding telemedicine and each physician's practice. Results: Of the 517 physicians who received the survey, 328 responded, for a 63.4% response rate. Of the 328 respondents, 84.1% did not use telemedicine in their practice prior to the COVID-19 pandemic. Even during the pandemic, the physicians most commonly responded that less than 5% of their practice was conducted by telemedicine (n = 103, 31.4%). The second most common response was that more than 20% of visits were done via telemedicine (n = 72, 22.0%); 43.0% of physicians noted that they would not use telemedicine technology in their practice after the pandemic, but 59.1% of physicians would be willing to do annual visits by telemedicine. Ability to examine the patient (2.0 ± 1.0) was rated worse, overall, than either the experience using the technology (3.2 ± 1.0) or the capacity to communicate with the patient (3.6 ± 1.0). Conclusions: Our survey of orthopedic surgeons demonstrates that while the use of telemedicine technology was minimal prior to the pandemic, its use was widely adopted during the pandemic. Nearly half of physicians said that they will continue to use telemedicine.

Telemedicine in an Outpatient Arthroplasty Setting During the COVID-19 Pandemic: Early Lessons from New York City.

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.

Early Recovery Outcomes in Patients Undergoing Total Hip Arthroplasty Through a Posterior Approach With Modified Postoperative Precautions.

BACKGROUND: Recent data suggest that a modified, more lenient set of precautions after total hip arthroplasty (THA) performed through the posterolateral approach may safely allow more patient movement and exercise in the immediate postoperative period. We hypothesize that 1) patients undergoing THA given modified precautions will demonstrate a fast-track return to functional activity and 2) wrist-based activity trackers will provide valuable information on postoperative activity levels. METHODS: We prospectively enrolled patients undergoing THA. Patients were given a wrist-based, commercially available activity tracker to wear 1 week preoperatively and 6 weeks postoperatively. Postoperative hip precautions included only the avoidance of the "leg-shaving" position of combined hip flexion, adduction, and internal rotation. Linear mixed models were used to analyze the change in steps and Hip Disability and Osteoarthritis Outcome Score-Junior (HOOS)-JR data. Pearson correlation coefficients were used to describe the relationship between average steps and HOOS-JR scores over time. RESULTS: Eighty-two patients were enrolled. Seventy-four percent returned to work by week 4. Seventy-six percent of left THA patients returned to driving by week 4. At 6 weeks, 23% of survey respondents were taking pain medication and 26% were using assistive devices. Average daily steps were 1098 at week 1, 2491 at week 2, 4130 at week 3, 4850 at week 4, 5712 at week 5, and 6069 at week 6. A significant correlation (R: -0.981) was found between increased weekly steps and improved HOOS-JR scores after THA (P < .001). CONCLUSION: Defining expected recovery timelines for patients undergoing THA helps surgeons counsel their patients preoperatively. Our study demonstrates an expected pathway for recovery after THA by using modified precautions that will be more clearly outlined with ongoing clinical data analysis.

EOS Imaging is Accurate and Reproducible for Preoperative Total Hip Arthroplasty Templating.

BACKGROUND: Templating is a critical part of preoperative planning for total hip arthroplasty (THA). The accuracy of templating on images acquired with EOS is unknown. This study sought to compare the accuracy and reproducibility of templating for THA using EOS imaging to conventional digital radiographs. METHODS: Forty-three consecutive primary unilateral THAs were retrospectively templated, six months postoperatively, using preoperative 2D EOS imaging and conventional radiographs. Two blinded observers templated each case for acetabular and femoral component size and femoral offset. The retrospectively templated sizes were compared to the sizes selected during surgery. Interobserver agreement was calculated, and the influence of demographic variables was explored. RESULTS: EOS templating predicted the exact acetabular and femoral size in 71% and 66% of cases, respectively, and to within one size in 98% of cases. The acetabular and femoral component size was more likely to be templated to the exact size using EOS compared to conventional imaging (P < .05). The femoral component offset choice was accurately predicted in 83% of EOS cases compared to 80% of conventional templates (P = .341). Component size and offset were not influenced by patient age, gender, laterality, or BMI. Interobserver agreement was excellent for acetabular (Cronbach's alpha = 0.94) and femoral (Cronbach's alpha = 0.96) component size. CONCLUSIONS: Preoperative templating for THA using EOS imaging is accurate, with an excellent interobserver agreement. EOS exposes patients to less radiation than traditional radiographs, and its three-dimensional applications should be explored as they may further enhance preoperative plans.

Anterior Cruciate Ligament Reconstruction Using Bone-Patellar Tendon-Bone Allograft in Patients Aged 50 and Older Leads to Improved Activity Levels and Acceptable Patient-Reported Outcomes.

PURPOSE: To evaluate patient-reported outcomes in patients aged 50 years and older undergoing anterior cruciate ligament reconstruction (ACLR) using bone-patellar tendon-bone (BPTB) allograft with minimum 2-year follow-up. METHODS: A retrospective review was performed on a consecutive series of patients aged 50 and older who underwent ACLR using BPTB allograft by a single surgeon with minimum 2-year follow-up. Postoperative International Knee Documentation Committee (IKDC), Lysholm, and Physical Component Summary of the 12-item Short-Form Health Survey were used to assess outcomes, as well as preoperative and postoperative Tegner activity scores, which were compared using a paired sample t test. RESULTS: Fifty patients met inclusion criteria, with a mean age of 55.3 ± 4.4 years and mean follow-up of 4.8 ± 1.9 years. Tegner activity scores improved from a mean preoperative score of 3.26 to a mean postoperative score of 5.25 (P < .001). The mean postoperative scores for Lysholm, IKDC, and Physical Component Summary were 87.3, 81.1, and 54.3, respectively. In total, 36 (72%) patients achieved a patient acceptable symptom state score for IKDC and 37 (74%) patients achieved a minimal clinically important difference for Tegner activity score. Thirty-eight (76%) patients reported good-to-excellent results, 6 (12%) patients reported fair results, and 6 (12%) patients reported poor results. CONCLUSIONS: ACLR with BPTB allograft in patients aged 50 and older leads to good patient-reported outcomes with significantly increased postoperative activity status at a minimum 2-year follow-up. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

High Offset Stems Are Protective of Dislocation in High-Risk Total Hip Arthroplasty.

BACKGROUND: Spinal stiffness has been shown to increase risk of dislocation due to impingement and instability. Increasing anteversion of the acetabular component has been suggested to prevent dislocation, but little has been discussed in terms of femoral or global offset restoration. The purpose of this study is to quantify dislocation rates after primary THA using standard versus high-offset femoral components and to determine how differences in offset affect impingement-free range of motion in a stiff spine cohort using a novel impingement model. METHODS: A total of 12,365 patients undergoing THA from 2016 to 2018 were retrospectively reviewed to determine dislocation rates and utilization of standard- versus high-offset stems. For 50 consecutive patients with spinal stiffness, a CT-based computer software impingement modeling system assessed bony or prosthetic impingement during simulated range of motion. The model was run 5 times for each patient with varying offsets. Range of motion was simulated in each scenario to determine the degree at which impingement occurred. RESULTS: There were 51 dislocations for a 0.41% dislocation rate. Total utilization of high-offset stems in the entire cohort was 49%. Of those patients who sustained a dislocation, 49 (96%) utilized a standard-offset stem. The impingement modeling demonstrated 5 degrees of added range of motion until impingement for every 1 mm offset increase. CONCLUSION: In the impingement model, high-offset stems facilitated greater ROM before bony impingement and resulted in lower dislocation rates. In the setting of high-risk THA due to spinal stiffness, surgeons should consider the use of high-offset stems and pay attention to offset restoration.

The Use of Robotic-Assisted Total Hip Arthroplasty in Developmental Dysplasia of the Hip.

BACKGROUND: Total hip arthroplasty (THA) is an effective operation for patients with hip osteoarthritis; however, patients with hip dysplasia present a particular challenge. Our novel study examined the effect of robot-assisted THA in patients with hip dysplasia. METHODS: We retrospectively reviewed patients with developmental dysplasia of the hip undergoing primary THA using robotic arm assistance at 2 institutions from January 2010 to January 2017. Patients undergoing revision arthroplasty were excluded. Preoperatively, all patients underwent a computed tomography scan so that 3-dimensional templating could be performed. Hip range of motion (ROM) and clinical leg length discrepancy were recorded preoperatively. Two independent observers calculated Crowe and Hartofilakidis grades for each operative hip. At the final follow-up, hip ROM, postoperative complications, and modified Harris Hip scores were obtained. RESULTS: Seventy-nine patients underwent THA because of degenerative joint disease in the setting of developmental dysplasia of the hip. There were 56 females and 23 males with a mean age of 45 years (range: 26-64 years). We found that components were placed according to the preoperative plan, that there was an improvement in the modified Harris hip score from 29 to 86 (P < .001), an improvement in the hip ROM (flexion improvement from 66° to 91°, P < .0001), and a correction of leg length discrepancy (17.1 vs 4 mm, P < .0002). There were no complications during the short-term interim follow-up (mean: 3.1 years). CONCLUSIONS: Robot-assisted THA can be a useful method to ensure adequate component positioning and excellent outcomes in patients with hip dysplasia. LEVEL OF EVIDENCE: Level III, Retrospective.

Long-term performance of oxidized zirconium on conventional and highly cross-linked polyethylene in total hip arthroplasty.

INTRODUCTION: Polyethylene wear and subsequent osteolysis remain obstacles to the long-term survivorship of total hip arthroplasty (THA). Highly cross-linked polyethylene (XLPE) with radical quenching represents a massive leap forward with dramatically improved wear rates compared to ultra-high molecular weight polyethylene (UHMWPE). In this study we evaluate the wear of UHMWPE and XLPE coupled with oxidized zirconium (OxZr) femoral heads. METHODS: A longitudinal, retrospective analysis was performed identifying consecutive patients who received a 28-mm OxZr-on-polyethylene primary THA from 2003 to 2004 by a single, high-volume arthroplasty surgeon. Patients were divided into two groups: those that received (1) UHMWPE liner and (2) a highly XLPE liner. Patients were included if clinical follow-up was complete to 2014 or later. Radiographic analysis was performed by two blinded observers. Measures included cup position, annual linear wear rate, and presence of osteolysis. Pairwise comparisons, correlations, and inter-rater reliability were calculated. RESULTS: Eighty patients were in the UHMWPE group with an average follow-up of 10 ± 1.23 years and 88 patients in the XLPE group with an average of 10 ± 1.03-year follow-up. Average age (68) was similar between groups (p = 0.288). Observer reliability was excellent for cup abduction (ICC = 0.940), anteversion (ICC = 0.942), and detection of osteolysis (ICC = 0.811). Annual linear wear rates were significantly higher (p = 1 × 10-19) with UHMWPE (0.21 ± 0.12 mm/year) compared to XLPE (0.05 ± 0.03 mm/year). Linear wear rate was significantly correlated to decreasing acetabular abduction (p = 0.035). Osteolysis was noted only in the UHMWPE group, with 17 patients (21.2%) exhibiting acetabular osteolysis and 37 (46.3%) patients exhibiting femoral osteolysis. CONCLUSIONS: OxZr coupled with XLPE showed minimal wear and no osteolysis at 10-year follow up. The yearly linear penetration rate is similar to that seen in other studies of XLPE THA. A careful longitudinal follow-up will be required to determine if advanced bearings such as OxZr or ceramic can show improved performance in the second decade of implantation.

Stiffness After Total Knee Arthroplasty: Is It a Result of Spinal Deformity?

BACKGROUND: There are no studies to date analyzing the effect of spinal malalignment on outcomes of total knee arthroplasty (TKA). Knee flexion is a well-described lower extremity compensatory mechanism for maintaining sagittal balance with increasing spinal deformity. The purpose of this study was to determine whether a subset of patients with poor range of motion (ROM) after TKA have unrecognized spinal deformity, predisposing them to knee flexion contractures and stiffness. METHODS: We retrospectively evaluated a consecutive series of patients who underwent manipulation under anesthesia (MUA) for poor ROM after TKA. Using standing full-length biplanar images, knee alignment and spinopelvic parameters were measured. Patients were stratified by pelvic incidence minus lumbar lordosis as a measure of spinal sagittal alignment with a mismatch of ≥10° defined as abnormal, and we calculated the incidence of sagittal spinal deformity. RESULTS: Average ROM before MUA was extension 3° and flexion 83°. About 62% of patients had a pelvic incidence minus lumbar lordosis mismatch of ≥10°. In the spinal deformity group, post-MUA ROM was improved for flexion only, whereas both flexion and extension were improved in the nondeformity group. CONCLUSION: Compensatory knee flexion because of sagittal spinal deformity may predispose to poor ROM after TKA. Patients with clinical suspicion should be worked up preoperatively and counseled accordingly.

Biplanar Low-Dose Radiography Is Accurate for Measuring Combined Anteversion After Total Hip Arthroplasty.

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.

Postoperative outcomes of total knee arthroplasty compared to unicompartmental knee arthroplasty: A matched comparison.

BACKGROUND: The purpose of this study was to evaluate early postoperative outcomes in patients following UKA (unicompartmental knee arthroplasty) compared to a matched cohort of TKA (total knee arthroplasty) patients. METHODS: Patients who met radiographic criteria for a medial UKA who underwent either a TKA or UKA at a single institution were matched based on age, gender, and BMI. RESULTS: One hundredy and fifty UKA in 138 patients and 150 TKA in 148 patients were included in this retrospective analysis. Mean age was 62.6 ±â€¯9 years and 65.2 ±â€¯9 years in the UKA and TKA groups respectively (p = .01). Patients who underwent UKA had significantly less pain at two and six weeks postoperatively compared to TKA patients with mean Numeric Pain Rating Scale (NPRS) scores of 3.7 ±â€¯1.1 vs. 7.8 ±â€¯1.2, p < .001 and 2.6 ±â€¯1.3 vs. 4.6 ±â€¯1.6, p < .001 respectively. Knee Society Scores (KSS) were higher in the UKA group at six weeks and two years postoperative (86.5 ±â€¯2.8 vs. 81.4 ±â€¯3.6, p < .001 and 89.5 ±â€¯2.4 vs. 84.5 ±â€¯3.3, p < .001 respectively). Return to work was faster in the UKA group (mean 20.6 ±â€¯7.89 vs. 38.6 ±â€¯6.23 days, p < .001). The UKA group also had higher mean Forgotten Joint Scores of 90.5 ±â€¯3.6 vs. 79.5 ±â€¯9.5 (p < .001). CONCLUSIONS: Patients with primarily medial compartment OA who underwent UKA had less postoperative pain, earlier return to work, and higher KSS compared to a matched group who underwent TKA.