Are Metal Ion Levels Elevated After Dual Mobility Acetabular Systems: Minimum Five-Year Analyses.

INTRODUCTION: While dual mobility systems in total hip replacements have demonstrated reduced dislocation and revision occurrences, concerns persist about the potential elevation of metal ions in the bloodstream, leading to negative tissue reactions. Notably, there's a scarcity of research spanning over five years post-surgery that examines cobalt and chromium levels after such implants. This study aimed to delve into these metal ion concentrations after a five-year period, building on previous metal-ion findings. We focused on: (1) cobalt concentrations in blood and urine; (2) chromium concentrations in blood and urine; (3) cobalt variations based on follow-up duration and specific implant metrics (e.g., offset, cup dimension, stem, and neck inclination); and (4) chromium variations based on the same parameters. MATERIALS AND METHODS: We tracked 57 individuals who received THA using modular dual mobility systems from January 1, 2011, to December 31, 2016, for an average span of six years (ranging from five to 10 years). At the final check-up, we measured cobalt and chromium levels in serum, plasma, blood, and urine. We also evaluated parameters like head composition and dimension, stem offset, cup dimension, and stem-neck inclination. RESULTS: Cobalt concentrations remained minimal, with average blood and urine values being 0.8+0.6mcg/L (standard <1.8mcg/L) and 1.2+1.0mcg/L (standard <2.8mcg/L), respectively. Two individuals exhibited a slight increase in blood cobalt concentration by 0.1 and 0.2mcg/L. Chromium averages in blood and urine were also minimal, with readings of 0.9+0.2mcg/L (standard <1.2mcg/L) and 1.3 + 0.5mcg/L (standard <2mcg/L), respectively. One individual had a marginally increased blood chromium concentration of 1.3mcg/L. Evaluations considering ceramic or cobalt-chrome heads, up to a decade of follow up, or varying implant metrics showed negligible variations in metal ion concentrations. CONCLUSION: The findings reveal that over a minimum of five years (average = six years; span, five to 10 years), cobalt and chromium concentrations in patients' systems remained within normal limits and were clinically insignificant, irrespective of the follow-up duration, head material, or implant specifications. This underscores the efficacy of dual mobility systems in ensuring minimal metal ion presence.

Dual Mobility Acetabular Systems for Total Hip Arthroplasty: A Multicenter Study and Technique Report.

INTRODUCTION: Dual mobility constructs for THA have been a tremendous advancement for hip arthroplasty surgeons, especially in scenarios where instability is a possibility. While some researchers have reported events of malseating with their use, the authors of the current study believe that this may be avoided by ensuring appropriate surgical technique. Therefore, the purpose of this study was to: (1) describe the surgical techniques that we employ to ensure that the liner is adequately seated; and (2) report the rates of malseating, dislocation, and aseptic loosening among our collective cohort of dual mobility THA patients. MATERIALS AND METHODS: All patients who underwent THA with a dual mobility construct between January 1, 2010 and December 31, 2018 at four institutions were identified. Those who had less than two years of follow up were excluded. Outcomes of interest included radiographic evidence of liner malseating, aseptic loosening, and dislocation. A total of 1,826 patients who underwent THA with a dual mobility construct were identified. Among these patients, 504 had less than two years of follow up and were excluded from our analysis. The remaining 1,322 patients met our criteria including 941 primary THAs (71.2%) and 381 revision THAs (28.8%). RESULTS: After a minimum follow-up period of two years, there were only two cases of malseated liners (0.15%). Serial follow ups have demonstrated no movement or changes in the position of the liners over time for both patients. In addition, they have been shown to have normal serum metal ion levels and no clinical complaints after 5.3- and 7.1-year follow up. Seven of 1,322 patients (0.53%) experienced a dislocation. Aseptic loosening of the acetabular cup was diagnosed in one patient 3.4 years postoperatively. In three patients, femoral component loosening occurred after a mean follow-up period of 2.3 years, (1.3 to 3.1 years). Among the 941 primary cases, the incidence of liner malseating was 0.21%, as both patients who experienced this complication were in this subgroup. As stated above, these patients have demonstrated normal serum metal ion levels and no clinical or radiographic sequelae as a result of the liner malseating. The dislocation rate among primary cases was 0.21% (2 of 941). Aseptic loosening of the acetabular component occurred in two (0.21%) while one patient (0.1%) was found to have femoral component loosening at final follow up. Of the 381 revision THAs, there were no cases of liner malseating. Five revision THA patients (1.3%) experienced a dislocation over our study period. Two revision THA patients experienced aseptic loosening of the femoral component (0.79%) at final follow up. CONCLUSIONS: The results of this paper demonstrate that malseating is not a prevalent issue with dual mobility THA when appropriate surgical techniques are used. It is hoped that that this paper clarifies the techniques for implantation of these implants and that excellent results can be achieved when care is taken to ensure that liners are well-seated intraoperatively.

Use of dual mobility cups in patients undergoing primary total hip arthroplasty with prior lumbar spine fusion.

BACKGROUND: Patients undergoing primary total hip arthroplasty (THA) with prior lumbar spine fusion (LSF) are a high-risk group for instability with reported incidence of dislocation as high as 8.3% using fixed bearing femoral heads. Purpose of this study was to determine risk of post-operative instability in patients undergoing primary THA with a history of prior LSF using dual mobility acetabular cups. METHODS: This was a multicenter retrospective study with 93 patients undergoing primary THA using a dual mobility cup with a prior history of instrumented LSF. There were 56 females and 47 males with an average age of 66 years (46-87) and average BMI of 30 with mean follow-up of 2.7 years (range 12-124 months). Surgical approach included posterior (63), direct lateral (15), anterior (11), and direct superior (4). Forty-four percent had one level lumbar fusion, 29% with two levels, and 15% with three or more levels fused. The primary outcome investigated was instability. RESULTS: There were no cases of instability or prosthetic joint infection in this group of patients with prior lumbar spine fusion undergoing primary THA using a dual mobility cup. There was one intra-operative periprosthetic femur fracture and one case of aseptic acetabular cup loosening. CONCLUSION: Patients undergoing THA with prior LSF are at increased risk for instability due to loss of normal spinopelvic relationship. The use of dual mobility cups in patients with prior LSF undergoing primary THA appears promising with no cases of instability in this high-risk group of patients.

Increased Survivorship of Cementless versus Cemented TKA in the Morbidly Obese. A Minimum 5-Year Follow-Up.

BACKGROUND: Total knee arthroplasty (TKA) in the morbidly obese patients can be challenging with an increased risk of complications. Studies have shown increased aseptic failures with well-aligned cemented TKAs in the obese patient. The purpose of this study is to determine if TKA in the morbidly obese (body mass index [BMI] ≥ 40) using cementless implants would demonstrate improved results and survivorship compared to cemented TKA at a minimum 5-year follow-up. METHODS: This is a retrospective study comparing clinical results of cemented vs cementless primary TKA with a posterior stabilized design TKA in morbidly obese (BMI ≥ 40) patients with minimal 5-year follow-up. There were 108 patients in the cementless group with a mean BMI of 45.6. In the cemented cohort, there were 85 cemented TKAs with a mean BMI of 45.0. Demographic, clinical, surgical, and radiographic data along with complications were extracted for all study patients. RESULTS: There were 5 failures requiring revision in the cementless group, including 1 for aseptic tibial loosening (0.9%). In the cemented group, there were 22 failures requiring revision, including 16 implants for aseptic loosening (18.8%; P = .0001). Survivorship with aseptic loosening as the endpoint was 99.1% in the cementless group vs 88.2% in the cemented cohort at 8 years (P = .02). CONCLUSION: Morbidly obese patients (BMI ≥ 40) have a higher failure due to aseptic loosening with cemented TKA with decreasing survivorship over time. The use of cementless TKA in morbidly obese patients with the potential of durable long-term biologic fixation and increased survivorship appears to be a promising alternative to mechanical cement fixation.

Multicenter Evaluation of a Modular Dual Mobility Construct for Revision Total Hip Arthroplasty.

INTRODUCTION: Modular Dual Mobility (MDM) constructs in total hip arthroplasty (THA) offer increased hip stability compared with constrained liners, without compromising hip range of motion. The purpose of this study was to evaluate outcomes of revision THA using MDM. METHODS: The study was a multiinstitutional retrospective cohort study of 315 hips that underwent revision THA using MDM between 2011 and 2017. Clinical outcomes and reasons for failure were collected. RESULTS: Three hundred fifteen patients met 1-year minimum follow-up (mean 3.3 years). Nine hips had instability postoperatively (2.9%), and 30 hips required reoperation (9.5%). Seven had recurrent instability (6.5%) which was associated with liner-only exchange (P = .021) and liner outer diameter of ≤ 38 mm (P = .016). CONCLUSION: Revision THA with MDM provided a low rate of instability and reoperation in a revision cohort. Recurrent instability following use of MDM in revision THA was associated with retention of the acetabular component and polyethylene outer diameter ≤ 38 mm. LEVEL OF EVIDENCE: Therapeutic Level III.

Outcomes of Dual Mobility Acetabular Cups in Total Hip Arthroplasty Patients.

BACKGROUND: Instability can account for over 20% of all revision total hip arthroplasties (THAs). Although a number of surgical techniques have been developed to limit the number of dislocations, prevention still remains a challenge. More recently, dual mobility (DM) cups have been developed to potentially target this problem. Although this implant design has been shown to have a number of potential advantages in the revision setting, there is limited data in the literature on the use of modular dual mobility (MDM) implants for primary THAs. Therefore, the purpose of this study was to evaluate cup survivorships, patient satisfaction outcomes, and complications of this device used for primary THA. MATERIALS AND METHODS: A total of 143 consecutive hips (131 patients) who underwent primary THA using DM prostheses by a high-volume academic surgeon were longitudinally followed up for a minimum of five years (mean: 6 years, 11 months; range, 6 years 3 months to 7 years 5 months). There were 77 women (54%) and 66 men (44%) who had a mean age 65 years (range, 34 to 90 years; SD, 11 years), and the mean body mass index (BMI) was 32 kg/m2 (range, 22 to 52; SD, 8 kg/m2). Patient demographics, (gender, BMI), as well as clinical outcomes were analyzed. Kaplan-Meier analysis was performed to determine aseptic, septic, and all-cause cup survivorship. Additionally, clinical outcomes based on Harris Hip Scores (HHS) and other modalities, as well as complications, were tabulated. Institutional review board (IRB) approval was received prior to initiating this study. RESULTS: Septic survivorship was found to be 99.3% (95% CI: 0.98 to 1.0), while all-cause survivorship was 98.6% (95% CI: 0.97 to 1.0). There were a total of two revision surgeries; however, these were not related to the MDM cup. Specifically, one patient had femoral stem loosening, while another patient had a late deep infection treated with a two-stage procedure. At most recent follow up, both patients were progressing well and had HHS scores of 85 and 92 points. The mean total HHS score was 95 points (range, 64 to 100) at most recent follow up. Other complications affecting patient outcomes included two patients who presented with concerns for deep vein thrombi, which were both medically managed, as well as one patient who had a non-fatal pulmonary embolism, which was also medically managed. The final HHS scores for these three patients were 83, 100, and 96 points. CONCLUSION: DM cups were designed with the intent of reducing hip instability. Most studies on these cups have reported on revision THA, where the problem of instability may be more paramount; however, fewer studies have reported on the use of this cup for primary THA. The findings from this study indicate excellent survivorship and overall clinical and patient satisfaction results using this construct. These five-year results are very encouraging and hopefully will portend excellent further survivorship with longer follow up.

Novel Acetabular Cup for Revision THA Improves Hip Center of Rotation: A Radiographic Evaluation.

BACKGROUND: Bone loss in patients undergoing revision THA poses a considerable challenge for orthopaedic surgeons. Often, to achieve better fixation in remaining bone, larger diameter acetabular components and reaming superiorly may be necessary. However, this is likely to raise the hip center of rotation, which may lead to altered biomechanics, specifically, insufficiency of the abductor muscles, altered gait, and increased risk of dislocation from impingement. More recently, a newer acetabular shell has been designed to more closely replicate the native hip center of rotation in these circumstances while maintaining adequate fixation. QUESTIONS/PURPOSES: The purpose of this study was to compare the radiographic parameters of this newer design with conventional hemispheric cups in revision THA. Specifically, we assessed the differences in (1) vertical center of rotation (COR) displacement and (2) horizontal COR displacement. METHODS: Between January 2016 and April 2016, five reconstructive surgeons at five institutions utilized a newer highly porous acetabular shell designed with peripheral screw holes and vertically eccentric COR to allow for restoration of center of hip rotation in revision THA. We included all patients who received this device. During this time, the general indications at these sites for using the new device included Paprosky Stage IIA, IIB, IIC, or IIIA acetabular defects. This yielded 29 patients who were subsequently matched (one to two) by cup size and sex to a cohort who underwent revision THA with conventional hemispheric cups between January 2015 and May 2016. To determine hip COR, radiographic measurements were performed. A circle contiguous to the acetabulum was drawn and the center was determined as the hip COR. All measurements were made from the interteardrop line for both the revised and native hips. A line through the teardrops was used for all horizontal measurements. Center position adjustments were made based on the manufacturer-specified values. Comparisons were performed using chi-square tests for categorical and t-tests for continuous variables. There was no difference in the severity of bone loss before the revision in the groups, as evidenced by Paprosky staging of preoperative radiographs. RESULTS: The mean vertical COR displacement was smaller in patients who had the novel cup (3.5 mm; range, -12 to 15 mm; mean difference, -7.3 mm; 95% confidence interval [CI], -13.2 to -1.5) as compared with those who had the conventional cup (10.5 mm; range, -4 to 50 mm; mean difference, 7.3 mm; 95% CI, -12.5 to -2.2; p = 0.003). There was no difference in mean horizontal displacement between the two groups (-0.06 ± 6.1 versus 1.7 ± 7.1; mean difference, -1.8; p = 0.903). CONCLUSIONS: Although hip COR was improved based on radiographic measurements with the use of this novel acetabular design, and although this may improve hip biomechanics, more studies are required before its widespread adoption for revision cases of this nature can be recommended. Both implant costs and the risks associated with using a new design in practice will have to be justified by studies that evaluate fixation, clinical function and implant survival, and patient-reported outcome scores, all of which were beyond the scope of this preliminary report. LEVEL OF EVIDENCE: Level III, therapeutic study.

Mid-Term Outcomes of Dual Mobility Acetabular Cups for Revision Total Hip Arthroplasty.

BACKGROUND: This study evaluated (1) survivorship, (2) clinical outcomes, (3) complications, and (4) radiographic outcomes of dual mobility (DM) systems when compared to fixed-bearing prostheses in revision total hip arthroplasty (THA). METHODS: A cohort of 85 patients who underwent revision THA using DM implants were compared to a prior matching cohort of 170 patients who received fixed-bearing implants. Mean follow-up time was 4 years in the DM cohort and 10 years in the fixed-bearing cohort. Kaplan-Meier analysis was performed to assess survivorships. Clinical outcomes were evaluated using the Harris Hip Score (HHS). Complications and radiographs were evaluated and reported at the final follow-up. RESULTS: Overall aseptic and all-cause survivorships of the DM cohort were 96.5% and 95.3% compared to 94.7% and 93.5% in fixed-bearing cohort (P = .01 for aseptic and all-cause survivorships). The DM cohort had statistically significant higher survivorship when compared at equivalent follow-up interval in the fixed-bearing cohort. There were 3 aseptic (one due to dislocation) and 1 septic revision in the DM cohort compared to 9 aseptic (6 due to dislocation) and 2 septic revisions in the fixed-bearing cohort. Postoperative HHS scores were 88 and 86 points in the DM and fixed-bearing cohorts. However, the difference in mean improvement in HHS scores from preoperative to postoperative (ΔHHS) was not statistically significant (35 vs 34, P = .533). Except for the aforementioned revisions, there were no progressive radiolucencies or osteolysis on radiographic evaluation in both cohorts. CONCLUSION: DM articulations demonstrated superior survivorship at equal follow-up intervals when compared to fixed-bearing implants and showed a trend toward lower dislocation rates.

Cementless Total Knee Arthroplasty in Knee Osteonecrosis Demonstrated Excellent Survivorship and Outcomes at Three-Year Minimum Follow-Up.

BACKGROUND: Lack of consensus exists on the use of cementless total knee arthroplasty (TKA) in patients with knee osteonecrosis. Therefore, this study was conducted to evaluate (1) implant survivorship; (2) clinical outcomes and complications; and (3) radiographic outcomes of primary cementless TKA in knee osteonecrosis. METHODS: This study included 46 patients (49 knees) who had knee osteonecrosis and underwent primary cementless TKA and had a mean follow-up of 44 months (range 36-96). Kaplan-Meier analysis was used to evaluate implant survivorship. Follow-up was performed post-operatively at 6 weeks, 3 months, and annually thereafter. Clinical outcomes including the Knee Society Scores (KSS) for pain and function, changes in range-of-motion, complications, and radiographic outcomes were analyzed. RESULTS: Aseptic implant survivorship was 97.9% (95% confidence interval 1.01-0.93) and all-cause implant survivorship was 95.9% (95% confidence interval 1.01-0.9), with 1 septic and 1 aseptic failures. The mean KSS for pain was 93 points (range 85-100) and the mean KSS for function was 84 points (range 70-90). Additionally, 1 patient had superficial wound necrosis and was treated with local wound care with no further sequela. Otherwise, no evidence of loosening, subsidence, or progressive radiolucencies were noted on radiological evaluation. CONCLUSION: Excellent implant survivorship, clinical, and radiographic outcomes of primary cementless TKA in the setting of knee osteonecrosis was demonstrated. Although further long-term study is needed to validate survivorship, new generation cementless TKA implants provide promising results in this subset of patients.

Cementless Posteriorly Stabilized Total Knee Arthroplasty: Seven-Year Minimum Follow-Up Report.

BACKGROUND: The purpose of this study is to evaluate (1) implant survivorship; (2) patient outcomes; (3) complications; and to (4) perform a radiographic analysis of cementless posteriorly stabilized total knee arthroplasty (TKA) patients at a minimum of 7-year follow-up. METHODS: Our original cohort was composed of 114 consecutive cementless posteriorly stabilized total knee arthroplasties (110 patients) performed by a single surgeon between 2008 and 2010. Since our original report, 4 (1 bilateral) patients died and 2 were lost to follow-up. Therefore, there were 104 patients who had 107 knees available for final follow-up. The final cohort included 43 men and 61 women, who had a mean age of 69 years (range 47-87) and were followed from 7 to 9 years (mean 8 years). Patient outcomes and complications were obtained from electronic medical records. Radiographic assessment was done using the Knee Society Radiographic Evaluation System. RESULTS: The all-cause survivorship was 98% (95% confidence interval 1.01-0.96). Since the original report, there has been 1 post-traumatic loosening of the tibial baseplate, and 1 revision for instability. There were no femoral revisions or patella revisions. The mean Knee Society pain score was 93 points (range 80-100) and the function score was 78 points (range 68-95). Excluding revisions, there was no evidence of progressive loosening of any implant components. CONCLUSION: Based on these 7-year minimum follow-ups, femoral, tibial, and patellar cementless hydroxylapatite-coated beaded implants perform well at up to 9 years postoperatively and offer surgeons and patients a cementless option that may provide long-lasting biological fixation.

Use of Neuromuscular Electrical Stimulation During Physical Therapy May Reduce the Incidence of Arthrofibrosis After Total Knee Arthroplasty.

INTRODUCTION: Arthrofibrosis remains a major complication following total knee arthroplasty (TKA) that negatively impacts patient outcomes and exhausts healthcare resources. The use of neuromuscular electrical stimulation (NMES) has demonstrated the ability to facilitate quadriceps muscle recovery and reduce pain. Therefore, the purpose of this study was to compare TKA patients who received physical therapy (PT) and adjuvant NMES therapy versus physical therapy alone in terms of: 1) rates of manipulation under anesthesia (MUA) to treat arthrofibrosis; and 2) post-therapy range of motion (ROM). MATERIALS AND METHODS: This was a retrospective review of TKA patients from multiple institutions who underwent physical therapy versus physical therapy and adjuvant NMES therapy following primary TKA. A total of 206 patients were reviewed in the two cohorts that either received PT alone (n=86) or PT and adjuvant NMES therapy (n=120). Data regarding the requirement of MUA postoperatively for treatment of arthrofibrosis were collected for every patient. Additionally, pre- and post-therapy knee ROM data was also collected. Outcomes in both cohorts were then compared and analyzed. RESULTS: Lower rates of arthrofibrosis requiring MUA were recorded in patients who used NMES therapy and PT when compared to PT alone (7.5% vs. 19.8%; p=0.009). Log regression analysis revealed lower odds of needing MUA in patients who utilized NMES therapy in adjunct with PT (odds ratio [OR]=0.36; 95% CI: 0.115 to 0.875; p=0.023). Patients who received the NMES therapy were shown to have a statistically greater mean improvement in ROM when compared to those patients who did not receive NMES (+2.63, p=0.04). Log regression analysis also demonstrated that post-PT ROM decreased the odds of receiving MUA with a larger ROM (OR=92; 95% CI: 0.824 to 0.9855; p<0.001). CONCLUSION: This study demonstrated that the use of NMES during PT may reduce the incidence of arthrofibrosis and improve patient ROM. Prospective, randomized controlled, and larger-scale studies are needed to validate these results. Nevertheless, this novel report demonstrated the positive outcomes for a new application of the NMES therapy.

No Decrease in Knee Survivorship or Outcomes Scores for Patients With HIV Infection Who Undergo TKA.

BACKGROUND: HIV is prevalent worldwide and numerous patients with this diagnosis ultimately may become candidates for TKA. Although some studies have suggested that complications are more common in patients with HIV who undergo TKA, these studies largely were done before the contemporary era of HIV management; moreover, it is unclear whether patients with HIV achieve lower patient-reported outcome scores or inferior implant survivorship. QUESTIONS/PURPOSES: We asked whether there were any differences in the outcomes of patients with HIV without hemophilia who undergo TKA compared with a matched control cohort in terms of: (1) patient-reported outcomes; (2) implant survivorship; and (3) complication rates. METHODS: Forty-five patients with HIV who had undergone 50 TKAs at three institutions with a minimum followup of 4 years between 2005 and 2011 were identified. An additional three patients were lost to followup before the fourth-year annual visit. All patients with HIV underwent thorough preoperative optimization with their primary care physician and infectious disease specialist. There were 31 men and 14 women with a mean age of 57 years and mean followup of 6 years (range, 4-10 years). These patients were compared with a matched cohort of 135 patients (one-to-three ratio) who did not have HIV and who had undergone a primary TKA by the same surgeons during this same period using the same implant. Matching criteria included patient age (within 2 years), BMI (within 2 kg/m2), surgeon performing TKA, followup (within 6 months), minimum followup of 4 years, sex ratio, and primary diagnosis (degenerative joint disease versus osteonecrosis). Approximately 10% of patients in the matching group had not returned for followup after their sixth annual visit. Outcomes evaluated included The Knee Society objective and function scores, University of California, Los Angeles (UCLA) activity scores, overall implant survivorship (free of revision) using Kaplan-Meier analysis, and complications. With the numbers available, there were no differences in preoperative Knee Society score or UCLA activity scores among the cohorts. RESULTS: With the numbers available, there were no differences in the mean Knee Society objective scores between patients with HIV (89 ± 11 points) and the matching cohort (91 ± 14 points) (95% CI, -7 to 3; p = 0.38). There were no differences among the Knee Society functional component as well (88 ± 12 points versus 90 ± 13 points; 95% CI, -6 to 2; p = 0.36) at latest followup. Similarly, there were no differences with the numbers available in the UCLA activity scores (6 ± 5 points [range, 4-7] versus 6 ± 7 points [range, 4-8]; p = 0.87) between the cohorts. With the numbers available, Kaplan-Meier analysis showed no significant difference in the overall implant survivorships between patients with HIV (98%; 95% CI, 94%-99%) compared with the matching group (99%; 95% CI, 98%-100%; p = 0.89). Postoperative complications were also comparable between the two groups. CONCLUSIONS: With the numbers available, we found that patients with HIV had no differences in clinical scores and implant survivorship compared with patients without the disease at mid-term followup. We believe practitioners should not be reluctant to perform TKA on this patient population. However, we believe the preoperative optimization process is crucial to achieving good outcomes and minimizing the risk of complications. Future comparative studies should have longer followup and a larger sample size with greater power to determine if there are differences in complications and implant survivorship. LEVEL OF EVIDENCE: Level III, therapeutic study.

Development and Verification of Novel Porous Titanium Metaphyseal Cones for Revision Total Knee Arthroplasty.

BACKGROUND: Porous metaphyseal cones are widely used in revision knee arthroplasty. A new system of porous titanium metaphyseal cones has been designed based on the femoral and tibial morphology derived from a computed tomography-based anatomical database. The purpose of this study is to evaluate the initial mechanical stability of the new porous titanium revision cone system by measuring the micromotion under physiologic loading compared with a widely-used existing porous tantalum metaphyseal cone system. METHODS: The new cones were designed to precisely fit the femoral and tibial anatomy, and 3D printing technology was used to manufacture these porous titanium cones. The stability of the new titanium cones and the widely-used tantalum cones were compared under physiologic loading conditions in bench top test model. RESULTS: The stability of the new titanium cones was either equivalent or better than the tantalum cones. The new titanium femoral cone construct had significantly less micromotion compared with the traditional femoral cone construct in 5 of the 12 directions measured (P < .05), whereas no statistical difference was found in 7 directions. The new porous titanium metaphyseal tibial cones demonstrated less micromotion in medial varus/valgus (P = .004) and posterior compressive micromotion (P = .002) compared with the traditional porous tantalum system. CONCLUSION: The findings of this biomechanical study demonstrate satisfactory mechanical stability of an anatomical-based porous titanium metaphyseal cone system for femoral and tibial bone loss as measured by micromotion under physiologic loading. The new cone design, in combination with instrumentation that facilitates surgical efficiency, is encouraging. Long-term clinical follow-up is warranted.

Outcomes of Newer Generation Cementless Total Knee Arthroplasty: Beaded Periapatite-Coated vs Highly Porous Titanium-Coated Implants.

BACKGROUND: Newer generation cementless total knee arthroplasty (TKA) designs are available and have novel implant coatings. We evaluated and compared beaded periapatite (PA)-coated vs highly porous titanium-coated cementless TKAs. Specifically, we compared: (1) survivorship, (2) Knee Society Scores (KSSs) and range of motion, (3) complications, and (4) radiographic findings. METHODS: There were 805 TKAs with beaded PA-coated tibial and patellar components (PA group; mean age 67 years; range 41-86 years), and 219 TKAs with highly porous titanium-coated tibial and patella components (mean age 66 years; range 34-88 years). Mean follow-up was 4.4 years (range 2-9 years; median 4 years). Implant survivorship was calculated using Kaplan-Meier curves. Student t-tests and chi-square tests were used as appropriate. Radiographic evaluation was performed using Knee Society Roentgenographic Evaluation and Scoring System. RESULTS: All-cause implant survivorship in beaded PA-coated group was 99.5% (95% CI, 97.9%-99.9%) and 99.5% (95% CI, 92.7%-99.9%) in highly porous titanium-coated group. There were no significant differences in the KSS for pain and function. Improvement in flexion and extension was similar in the 2 groups. Overall, complication rate (2.2% vs 2.3%; P = .274) and number of revisions (6 [0.8%] vs 2 [0.2%]; P = .936) were similar in the 2 groups. Excluding the aseptic and septic failures, there were no progressive radiolucencies or osteolysis on radiographic evaluation. CONCLUSION: This study has shown good clinical and patient-reported outcomes of cementless TKA for both implants. Future multicenter large scale clinical and cost-effectiveness studies are needed to determine the superiority of one cementless implant type over the other.

Does Hepatitis C Affect the Clinical and Patient-Reported Outcomes of Primary Total Hip Arthroplasty at Midterm Follow-Up?

BACKGROUND: It is estimated that 3%-6% of orthopedic patients, many of whom may undergo lower extremity total joint arthroplasty, are infected with hepatitis C. The purpose of this study was to assess the outcomes of patients with hepatitis C who undergo total hip arthroplasty (THA) in comparison with a matched control cohort in terms of (1) patient-reported outcomes, (2) implant survivorship, and (3) complications. METHODS: Fifty-four hips in 49 hepatitis C-infected patients who underwent a primary THA between 2002 and 2011 were reviewed. This included 10 women and 39 men who had a mean age of 57 years and a mean 6.5-year follow-up. These patients were matched to 163 THAs (148 patients) who did not have this disease and underwent a THA during the same period. We compared implant survivorship, complication rates, Harris hip scores, and University of California, Los Angeles, activity scores. Radiographs were evaluated for loosening, fracture, malalignment, and osteolysis. RESULTS: The implant survivorship in the hepatitis C-infected patients and comparison group was 96.2% and 98.7%, respectively. The risk of revision surgery in the hepatitis C cohort was 3-fold higher than the comparison group; however, this difference was not significant (P = .26). The hepatitis C-infected cohort had a higher risk of surgical complications (odds ratio = 6.5; P = .034). There were no differences in postoperative Harris hip scores or University of California, Los Angeles, activity scores between the cohorts. CONCLUSION: Hepatitis C patients can achieve good implant survivorship and clinical outcomes after THA. However, these patients may be at an increased risk for surgical complications and revision rate.

What Influences How Patients with Depression Rate Hospital Stay After Total Joint Arthroplasty?

BACKGROUND: Recent healthcare reform has spurred important changes to provider reimbursement. With the implementation of the Value Based Purchasing program, significant weight is placed on patient experience of care. The Press Ganey (PG) survey is currently used by over 10,000 hospitals, as it serves to help optimize patient satisfaction. However, confounding factors, such as clinical depression, are not screened against by PG. Thus, arthroplasty surgeons performing lower extremity total joint arthroplasty (TJA) may have difficulty optimizing patient satisfaction while caring for patients with clinical depression. Therefore, we asked: 1) What Press Ganey elements affect the overall hospital rating in patients who suffer from clinical depression? and 2) Are survey responses different between patients who do and do not have clinical depression? MATERIALS AND METHODS: We queried our institutional PG database for patients who underwent a TJA from November 2009 to January 2015. Our search yielded 1,454 patients, of which 204 suffered from depression and 1,250 did not. Multiple regression analysis was performed to determine the influence (b weight) of selected PG survey domains on overall hospital rating. The weighted mean for domain was also calculated. RESULTS: Multiple regression analyses showed that overall hospital ratings were significantly influenced by communication with nurses (b-weight = 0.881, p< 0.001) in post-TJA patients with depression. The remaining domains were not statistically significant. There were no significant differences in individual PG elements for patients who did and did not have depression. CONCLUSION: Overall patient satisfaction among patients with depression was greatly influenced by communication with nurses. Understanding these challenges may encourage care coordination across disciplines for the management of patients with depression before and after surgery. As a result, this could optimize orthopedic surgery outcomes, but, more importantly, patient health and satisfaction, while reducing costs of care.

Dual Mobility Acetabular Cups in Primary Total Hip Arthroplasty in Patients at High Risk for Dislocation.

INTRODUCTION: Postoperative dislocation occurs in approximately 2% of primary total hip arthroplasties (THAs). Risk factors associated with dislocation include: age of 70 years or older, body mass index (BMI) of 30 kg/m2 or greater, alcohol abuse, and neuro-degenerative diseases such as multiple sclerosis or Parkinson's disease. As a result, dual-mobility articulations, which have been typically used for revision procedures, have become an increasingly popular option for these "at risk" primary THAs. Few studies have assessed their use in this complex patient population. Therefore, the purpose of this study was to assess: 1) survivorship; 2) radiographic outcomes (cup migration, progressive radiolucencies, and changes in component position); 3) Harris Hip Scores; and 4) complications of the dual-mobility articulation in the setting of primary THA for patients at high risk for dislocation. MATERIALS AND METHODS: Five participating surgeons performed 495 primary cementless THAs between January 2011 and December 2013. During this time, four of the five surgeons used dual-mobility articulations whenever the acetabular cup size was 52 mm or greater to allow for a 28 mm head, while one surgeon used it when the cup size was less than 52 mm to allow for an effective head size of 38 mm. The remaining surgeon used it for all THAs. Of the 495 patients, 453 (92%) received dual-mobility articulations, of which, 43 patients (10%) were lost to follow-up before the two year minimum. The remaining 410 patients were further assessed to determine those who were considered high risk for dislocation (age = 70 years, BMI =30 kg/m2, had a diagnosis of alcohol abuse, or had a neuro-degenerative disorder). Two hundred forty-nine patients were included in the analysis (103 men, 146 women) who had a mean age of 66 years (range, 24 to 90 years). The mean follow-up was 3.3 years (range, 2 to 5 years). Kaplan-Meier analysis was performed to assess aseptic and all-cause acetabular cup survivorship. Radiographs were evaluated for cup migration, progressive radiolucencies, and any changes in component position. Clinical outcomes were assessed using the Harris Hip Score (HHS), and any surgery-related complications were recorded. RESULTS: The survivorship to aseptic failure (n= 1) and all-cause (aseptic, n= 1; septic, n= 1) Kaplan-Meier acetabular component survivorships were 99.6% (95% confidence interval [CI], 99.1% to 99.9%) and 99.2% (95% CI, 98.5% to 99.9%), respectively. One hip had impingement of an anteverted cup, resulting in trunnion notching, and required revision of the cup and stem. Another hip had a deep infection, which was treated with a two-stage revision procedure. There were no dislocations in this cohort. No progressive radiolucencies or component positional changes were seen on radiographic assessment. Patients reported a mean HHS of 92.5 (range, 47 to 100 points) at final follow-up. Surgical complications included one polyethylene liner that was incompletely seated, and one loose femoral stem, which required revision of only the femoral component. CONCLUSIONS: At short-term follow-up, dual-mobility articulations in primary THA offer survivorship, outcomes, and complications comparable to conventional THA designs in patients who are at increased risk for postoperative dislocation. Serious complications, such as polyethylene wear and intraprosthetic dislocations, have occasionally been reported with the use of these components. Therefore, future studies should be prospective, multi-center, and have longer-term follow-up to determine the true benefit of modular dual-mobility articulations in patients who are at high risk for dislocation.

Early experience with dual mobility acetabular systems featuring highly cross-linked polyethylene liners for primary hip arthroplasty in patients under fifty five years of age: an international multi-centre preliminary study.

PURPOSE: To evaluate early performance of contemporary dual mobility acetabular systems with second generation annealed highly cross-linked polyethylene for primary hip arthroplasty of patients under 55 years of age. METHODS: A prospective observational five years study across five centers in Europe and the USA of 321 patients with a mean age of 48.1 years was performed. Patients were assessed for causes of revision, hip instability, intra-prosthetic dissociation, Harris hip score and radiological signs of osteolysis. RESULTS: There were no dislocations and no intra-prosthetic dissociations. Kaplan Meier analysis demonstrated 97.51% survivorship for all cause revision and 99.68% survivorship for acetabular component revision at five years. Mean Harris hip score was 93.6. Two acetabular shells were revised for neck-rim implant impingement without dislocation and ten femoral stems were revised for causes unrelated to dual mobility implants. CONCLUSION: Contemporary highly cross-linked polyethylene dual mobility systems demonstrate excellent early clinical, radiological, and survivorship results in a cohort of patients that demand high performance from their implants. It is envisaged that DM and second generation annealed HXLPE may reduce THA instability and wear, the two most common causes of THA revision in hip arthroplasty.

Low Frequency of Early Complications With Dual-mobility Acetabular Cups in Cementless Primary THA.

BACKGROUND: Dislocation complicates 1% to 5% of primary total hip arthroplasties (THAs). As a result, some surgeons consider dual-mobility articulations, which are usually used in the revision setting to decrease the likelihood of dislocation, as an option for primary THA. However, few studies have evaluated their use in this setting. QUESTIONS/PURPOSES: (1) What is the cup survivorship when the dual-mobility articulation is used in the setting of primary THA? (2) What are the clinical outcomes with this approach? (3) What are the radiographic outcomes? (4) What are the complications of dual-mobility articulations in primary THA? METHODS: Between 2011 and 2013, the five participating surgeons performed 495 cementless primary THAs. During that time, one of the five surgeons used dual-mobility articulations for all THAs, and the other four used it whenever the acetabular cup size was 52 mm or greater to enable a 28-mm head. Of the 495 patients, 453 (92%) were performed using this device. Smaller patients were treated with a standard THA. Of the 453 patients, a total of 43 patients (10%) were lost to followup before the 2-year minimum. The resulting 410 patients who were included in the analysis (164 men, 246 women) had a mean age of 64 years (SD, 12 years). The mean followup was 3 years (SD, 0.7 years). We performed Kaplan-Meier analyses to assess survivorship to aseptic failure and all-cause acetabular component survivorship. Clinical outcomes were evaluated using the Harris hip score (HHS); radiographs were assessed for cup migration, progressive radiolucencies, and positional changes of the components; and any surgery-related complications were recorded. RESULTS: The survivorship to aseptic failure and all-cause acetabular component survivorship was 99.8% (failures, n = 1) (95% confidence interval [CI], 4.517-4.547) and 99.3% (failures, aseptic, n = 1; septic, n = 2) (95% CI, 4.494-4.543); one hip had trunnion notching caused by impingement of a malpositioned cup, which was treated with revision of the cup and stem; and two patients had periprosthetic infections that were treated with two-stage revisions. There were no dislocations. Patients had a mean HHS of 94 (SD, 6) at final followup. On radiographic evaluation, no progressive radiolucencies or positional changes of the components were identified. Surgical complications included one traumatic avulsion of the abductors, one traumatic avulsion of the greater trochanter, which was repaired without revision of any of the components, and one loose femoral stem, which required revision of the femoral component only. CONCLUSIONS: Dual-mobility cups in primary THA yield seemingly comparable survivorship and complications to conventional THA bearings at short-term followup. Because serious complications have occasionally been reported with the use of these bearings, larger, longer term, comparative-and ideally, randomized-trials will be needed to establish the superiority of one approach over the other. Until or unless such studies show the superiority of dual-mobility designs for primary THA, we recommend that in the setting of uncomplicated primary THA, dual-mobility articulations be used only in centers that track their results carefully or in research protocols. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Midterm Outcomes Following Total Knee Arthroplasty in Lupus Patients.

BACKGROUND: An increasing number of patients with systemic lupus erythematosus (SLE) are undergoing total knee arthroplasty (TKA), but there are few studies detailing their outcomes. The purpose of this study was to evaluate TKA cohort of patients who had SLE compared with a matched cohort who did not have this disease by analyzing (1) implant survivorship, (2) functional outcomes, (3) complication rates, (4) health-related quality of life, and (5) patient-perceived activity level. METHODS: A retrospective review of all patients who underwent TKA and had an International Classification of Diseases, Ninth Revision, code diagnosis for SLE was performed at 3 high-volume institutions. A total of 31 patients (34 arthroplasties) were identified, and they were compared with a matched cohort (1:3) who did not have SLE and had undergone a primary TKA during this same time period. RESULTS: After a mean 6-year follow-up (range, 2-10 years), both cohorts had similar implant survivorship (91% vs 99%). In addition, each cohort had similar complication rates (odds ratio = 1.9, 0.99-13). Functional outcomes were similar as measured by Knee Society Scores objective (90 vs 91 points) and functional (89 vs 90 points). There were no differences in Short Form-36 physical (47 vs 49 points) or mental components (51 vs 53 points). University of California Los Angeles activity scores were similar as well (5.1 vs 5.9 points). CONCLUSIONS: Our study demonstrated comparable excellent clinical and patient-reported outcomes of TKA in patients with or without SLE. Prospective studies are necessary to evaluate these outcomes at longer follow-up.