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.

Cementless Total Knee Arthroplasty Using a Highly Porous Tibial Baseplate in Morbidly Obese Patients: Minimum 5-Year Follow-Up.

Morbidly obese patients undergoing cemented primary total knee arthroplasty (TKA) can pose a challenging problem with implant survivorship due to greater stress at the cement-bone interface. With the advent of additive manufacturing (three-dimensional printing), highly porous implants are now readily available. The purpose of this study was to review the results of primary TKA in the morbidly obese (body mass index [BMI] ≥ 40) patient using a highly porous cementless tibial baseplate. This is a retrospective study of 167 TKAs in patients with morbid obesity undergoing primary cementless TKA with a minimum 5-year follow-up. A total of 6 patients died and 14 were lost to follow-up, leaving 147 TKAs in 136 patients with a mean follow-up of 66 months (range 60-79 months). The average age was 59 years (range 36-84 years) and average BMI was 45 kg/m2 (range 39.5-63.9). Clinical results, patient-reported outcome measures, radiographs, and complications were reviewed. There were 9 failures requiring revision, including 3 for aseptic tibial loosening (2.0%), 2 for deep infection (1.4%), 2 for patellar resurfacing (1.4%), 1 for patella instability (0.7%), and 1 for extensor mechanism rupture (0.7%). Knee Society Score (KSS) improved from 48 to 90 at 2- and 5-year follow-up. KSS function score improved from 49 to 68 and 79 at 2- and 5-year follow-up, respectively. Survivorship with aseptic loosening as the endpoint was 98.0% at 5 years. Cementless TKA using a highly porous tibial baseplate in morbidly obese patients demonstrated excellent clinical results with 98% survivorship at 5 years and appears to offer durable long-term biologic fixation as an alternative to mechanical cement fixation in this challenging group of patients.

Wound Management following Total Knee Arthroplasty: An Updated Review.

Optimal wound closure techniques following total knee arthroplasty (TKA) have focused on enhancing healing potential, preventing infection, yielding satisfactory cosmesis, and allowing early ambulation and functionality. An appropriate layered closure and management of the TKA typically involves addressing the (1) deep fascial layer; (2) subdermal layer; (3) intradermal layer, including the subcuticular region; and (4) final application of a specific aseptic dressing, each of which are covered here in detail. This focused critical review of the literature discusses traditional techniques used in all layers of wound closure following TKA while introducing several emerging popular techniques. For example, absorbable barbed skin sutures and occlusive dressings have the potential to reduce operative time, limit the need for early postoperative visits, obviate the need for suture or staple removal, and safely promote patient communication via telemedicine. As novel wound closure techniques continue to emerge and traditional approaches are improved upon, future comparative studies will assist in elucidating the key advantages of various options. In an extremely important field that has tremendous variability, these efforts may enable the reaching of a classically elusive standard of care for these techniques.

The Accuracy of Computed Tomography-Based, Three-Dimensional Implant Planning in Robotic-Assisted Total Knee Arthroplasty.

Advanced imaging used in robotic-assisted total knee arthroplasty (TKA), such as computed tomography (CT)-based three-dimensional (3D) planning, may provide an accurate means of implant sizing preoperatively. The purpose of this study was to examine preoperative CT-based implant planning accuracy for robotic-assisted TKA in patients who have (1) varus deformities, (2) valgus deformities, (3) neutral alignment, and (4) retained hardware. A total of 393 patients underwent a robotic-assisted TKA by a single surgeon received preoperative CT scans. The surgeon reviewed the CT-based model preoperatively and recorded the expected size of the components. The final implants used in each case were recorded and compared with the surgeon's preoperative plan. In all groups of patients, the surgeon's CT-based implant plan was within one size of the implant utilized 100% of the time for both the tibiae and femora. Overall, the surgeon was exactly matched in 319 (81%) and 315 (80%) cases for the femoral and tibial components, respectively. For the femoral component, the mean age for patients in whom the original plan was exactly matched was younger than those whose implants were upsized and older than patients those implants were downsized (p = 0.024). Other patient demographics and preoperative knee alignment were not associated with predictive accuracy for femoral or tibial components. Our results demonstrate how preoperative CT-based, 3D planning for robotic-assisted TKA is accurate to within one size of the components in every case (100%), and exactly matched in 80%. The results of this study are important because they demonstrate how CT-based preoperative implant planning for TKA is reliable and accurate across all native knee alignments and other patient-specific factors. In addition, they build on a previous study by the same single surgeon, demonstrating that predictive ability can improve over time. This may be important as we move toward more outpatient surgery with less ability for prostheses inventory at ambulatory sites.

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.

Outcomes of Cementless-Backed Patellar Components.

Because of the early follow-up positive outcomes with cementless fixation, continued evaluations need to be performed to ensure longer-term efficacy. Additionally, although many studies report on the results of femoral and tibial component fixation, few studies report specifically on patellar outcomes. Therefore, the purpose of this study was to report on the: (1) implant survivorship; (2) complications; and (3) radiographic outcomes in a large cohort of patients who received cementless total knee arthroplasties (TKAs), with particular attention to the patellar component. A total of 261 patients who underwent cementless TKA by a single, high-volume academic surgeon were studied. Patients had a mean age of 66 years and were distributed between 192 women (74%) and 69 men. All patients received the same cementless tibial, femoral, and patellar components. Mean follow-up period was 4.5 years (range, 4-5 years). Primary outcomes evaluated included all postoperative complications, with particular emphasis on the patellar component. Only one patellar loosened leading to a patellar aseptic loosening rate of 0.3% (1 of 261). The one patellar loosening was the component being dislodged after a manipulation under anesthesia (MUA) at 6 weeks. This was revised to a cemented component and the patient is doing well 4 years later. A second patient experienced a patellar tendon rupture, later surgically repaired. Another patient sustained a patella fracture that was managed nonoperatively. The fracture healed by 1 year and the patient continued to have an otherwise successful outcome, now at 2 years follow-up. No progressive radiolucencies, subsidence, or changes in initial postoperative axial alignment were observed at final follow-up. The results from this study highlight a 98% success rate at mean 4.5 years follow-up in a large cohort of patients with a diverse spread of demographic details. Specific to the patella, only one patient experienced an adverse event, which was managed nonoperatively. Therefore, based on this data, patellar fixation in cementless TKA can be considered a safe technique.

Cementless Tritanium Baseplate Total Knee Arthroplasty: Survivorship and Outcomes at 5-Year Minimum Follow-Up.

BACKGROUND: Newer generation cementless total knee arthroplasty (TKA) designs have provided stronger osteointegration between the implant and bone. Despite excellent survivorship and outcomes with cemented TKAs, areas of concern within the bone-cement interface remain a concern and necessitate studies on alternative constructs. This study assesses: (1) implant survivorship; (2) clinical outcomes; and (3) complications with radiographic outcomes at a 5-year minimum follow-up of cementless highly porous titanium-coated baseplates in TKAs. METHODS: Part of this study has been reported. We retrospectively reviewed a prospectively collected database at a single high-volume institution between July 1, 2013 and June 30, 2014 for patients who underwent a primary TKA using cementless highly porous titanium-coated baseplate implants. Patients were evaluated clinically at postoperative follow-up visits at a minimum of 5 years. To calculate the survivorship, Kaplan-Meier analysis was performed to determine all-cause, aseptic, and septic implant survivorship at each final follow-up for all patients. RESULTS: A total of 228 TKAs were performed and followed for a minimum of 5 years (range, 5-6 years). As of the latest follow-up, one case of septic loosening of the patellar button and one case of patellar dislodgment secondary to physical manipulation were recorded and revised. Overall, the cohort displayed implant survivorship of 99.5% at 5-year minimum follow-up. Improvements were seen in both Knee Society pain and function scores and were 37 points (range, 17-60 points) and 28 points (range, 15-47 points), respectively. The mean improvement in flexion was 17.8 (range, -20 to 40 degrees) and mean improvement in extension was -5.5 (range, -30 to 5 degrees). DISCUSSION: Cementless TKAs serve as strong alternative choice to cemented TKAs. Although cemented fixation is commonly known as the gold standard, results of this study confirm the findings of previous investigations on the survivorship of cementless TKA implants. Therefore, patients who undergo primary TKA with a cementless tritanium baseplate can expect excellent clinical outcomes at a 5-year minimum follow-up.

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.

Cementless 3D Printed Highly Porous Titanium-Coated Baseplate Total Knee Arthroplasty: Survivorship and Outcomes at 2-Year Minimum Follow-Up.

Newer generation cementless total knee arthroplasty (TKA) implants continue to develop with demonstrated clinical success in multiple recent reports. The purpose of this study was to investigate (1) survivorship, (2) complications, and (3) clinical outcomes of a newer generation cementless and highly porous titanium-coated base plate manufactured using three-dimensional (3D) printing technology. We reviewed a single-surgeon, longitudinally maintained database of patients who underwent primary TKA using cementless, highly porous titanium-coated base plate implants from July 1, 2013 to December 31, 2016. A total of 523 patients were identified. Of this cohort, 496 patients had a minimum of 2-year follow-up and were included in our final analysis. Among these patients, 72 had bilateral TKA yielding a total of 568 TKAs. There were 133 men and 363 women who had a mean body mass index of 33 kg/m2 (range, 20-61 kg/m2). The mean age was 66 years (range, 33-88 years). Average follow-up was 36 months (range, 24-48 months). Indications for TKA included osteoarthritis in 432 patients (87%), rheumatoid arthritis in 40 patients (8%), and knee osteonecrosis in 24 (5%) patients. Implant survivorship was defined as any revision leading to explantation of the base plate for any reason. Kaplan-Meier analysis was performed to determine all-cause implant survivorship at final follow-up for every patient. Complications were assessed using the Knee Society standardized list of TKA complications. Clinical outcomes were determined using the Knee Society pain and function scores. Range-of-motion values were also collected. There were a total of four failures, all were due to aseptic loosening with a survivorship rate of 99% at mean follow-up of 3 years (95% confidence interval = 0.984-0.999). In addition, there were a total of 12 surgical and 10 medical complications. Surgical complications did not affect the base plate or result in any additional implant revisions. A total of nine patients had thromboembolic disease complications; all received medical treatment and recovered adequately. Radiological evaluation did not show any signs of loosening or failures in other patients at final follow-up. Knee Society Scores for pain and function improved from 55 and 56 points preoperatively to 92 and 84 points at 2 years postoperatively. Our results are in concordance with the excellent clinical outcomes and survivorship demonstrated for the newer generation cementless TKA implants. In our experience, 3D printed titanium base plates demonstrated clinical success and excellent survivorship at minimum follow-up of 2 years.

Reducing perioperative blood loss with antifibrinolytics and antifibrinolytic-like agents for patients undergoing total hip and total knee arthroplasty.

Total hip and knee arthroplasties may be associated with a significant amount of perioperative blood loss. The severity of blood loss may be great enough to require the use of blood transfusions to treat perioperative anemia. Various methods of blood preservation have been studied. The use of antifibrinolytics and antifibrinolytic-like agents to reduce perioperative bleeding has been researched in orthopaedics and other surgical subspecialties. This review aims to evaluate the current evidence supporting the use of tranexamic acid, aminocaproic acid, fibrin tissue adhesive, and aprotinin in the reduction of perioperative blood loss in total hip and knee arthroplasties.

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.

Top 100 Most-Cited Clinical Studies of Hip and Knee Arthroplasty: The Foundation of Practice.

Total number of citations has been considered a proxy for a published study's importance within a given field. However, there are multiple pitfalls to correlating the total number of citations alone with the quality of a study. In this review, the authors aimed to identify the top 100 most-cited studies of hip and knee arthroplasty and then assess study design and quality of reporting. More than half of these studies were level IV evidence, unblinded, not randomized, and not controlled. This underscores the need for higher-quality study design to support practice. [Orthopedics. 2019; 42(2):e151-e161.].

Accelerated Growth of Cellular Therapy Trials in Musculoskeletal Disorders: An Analysis of the NIH Clinical Trials Data Bank.

The purpose of this study was to (1) determine the growth rate and the trends of musculoskeletal cellular therapy trials in the National Institutes of Health Clinical Trials Data Bank; (2) analyze the study design and characteristics; and (3) assess which cellular therapies and disease conditions are studied. A systematic review of musculoskeletal clinical trials from 2005 to 2016 using cell-based therapies as the primary intervention was performed through ClinicalTrials.gov. The number of musculoskeletal cell-based clinical trials is increasing, with most being early stage, phase I/II, and using autologous cells harvested mostly from bone marrow to target cartilage-related diseases. Among the 282 clinical trials identified, only 99 (35.1%) were completed; 62 of the 99 (62.6%) did not list any related publications. [Orthopedics. 2019; 42(2):e144-e150.].

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.

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.

Cementless Total Knee Arthroplasty: A Comprehensive Review of the Literature.

This review evaluated (1) original and newer cementless implants; (2) outcomes of newer designs; (3) risks and benefits; and (4) newer cementless vs cemented total knee arthroplasties. A search for all reports on cementless total knee arthroplasties published from January 2010 to April 2017 was performed, and 31 studies were included for final analysis. Newer cementless total knee arthroplasty designs have shown excellent survivorship, functional outcomes, and satisfaction rates in both young and elderly populations. Compared with cement fixation, there may be potential benefits with the newer cementless implants. However, these findings need to be further substantiated with additional studies reporting longer-term results. [Orthopedics. 2018; 41(5):263-273.].

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.

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.