Instability in Patients With Lumbar Spine Disease Undergoing Posterior Approach and Lateral Approach Primary Total Hip Arthroplasty.

INTRODUCTION: Dislocation rates in patients who have fixed spinopelvic motion have been reported up to 20%. Few studies have directly compared dislocation rates in patients who have spine pathology undergoing total hip arthroplasty (THA) through different surgical approaches. This study compared postoperative dislocation rates in patients who had lumbar spine disease and underwent primary THA using a posterior or direct lateral approach. METHODS: Between 2011 and 2017, consecutive cohorts of primary THAs were retrospectively reviewed. One surgeon routinely used a posterior approach, while the other used a direct lateral approach. Chart and radiographic review were conducted to identify patients who had lumbar spine disease. Dislocations among cohorts with and without lumbar spine disease were compared by posterior and direct lateral approaches. RESULTS: The overall dislocation rate was 1.3% (15/1,198). The top four predictors of dislocation were presence of lumbar spine disease (odds ratio [OR] 5.0; P = 0.014), posterior surgical approach (OR, 6.5; P = 0.074), cases performed for fracture (OR, 4.4; P = 0.035), and women (OR, 4.6; P = 0.050). Dislocation rates among direct lateral approach patients who had lumbar spine pathology were significantly lower than posterior approach patients who had lumbar spine pathology (0.0% versus 3.6%; P = 0.011). DISCUSSION: Although dislocation rates were low in both groups, study results suggest that a direct lateral approach for primary THA may reduce postoperative dislocations for patients who have limited spinopelvic motion due to lumbar spine pathology. Furthermore, surgeons using the posterior approach might consider optimizing the femoral head to acetabular cup ratio in patients who have lumbar spine disease.

Incidence and Predictors of Subsidence Using Modular, Tapered, Fluted Titanium Femoral Stems in Aseptic Revision Total Hip Arthroplasty.

BACKGROUND: Tapered, fluted titanium (TFT) femoral stems have become the gold standard in revision total hip arthroplasty (rTHA). However, there is a paucity of data on TFT stem subsidence rates following aseptic rTHA. Subsidence can lead to instability, mechanical failure, leg-length discrepancy, and may require revision surgery. This study evaluated the incidences and predictors of TFT subsidence in aseptic rTHA. METHODS: A total of 102 TFT femoral stems of 4 designs were retrospectively reviewed. Stem subsidence was measured on digital radiographs taken immediately after surgery and at standard clinical follow-up. Patient characteristics, risk factors for subsidence, revision etiologies, and implant characteristics were recorded. Patient-reported outcome measures were also evaluated for a subset of cases. RESULTS: Overall, 12% of stems subsided >1 cm, and subsidence was minimal (<3 mm) in ≥64% of cases. From immediate postoperative to 1-month radiographic follow-up, 79% of stems subsided a mean of 2.9 mm (range, 0.1 to 12 mm). Beyond 1 month, subsidence was minimal for ≥77% of cases. In multivariate analyses, women and less femoral implant canal fill were associated with greater subsidence (P ≤ .034). The TFT stem design was not associated with early subsidence (P = .816). There were no modular junction fractures. There were 2 fractures and 2 subsidence-related revisions for aseptic loosening that occurred postoperatively. CONCLUSIONS: The amount of subsidence in TFT stems was low and was detectable in the early (less than 1 year) postoperative period. Maximizing TFT stem fill within the femoral canal appears to reduce the risk of subsidence without increasing femoral fracture rates and should be the goal with implantation of these devices. LEVEL OF EVIDENCE: IV-Case Series, No Control Group.

Nutritional Laboratory Studies Prior to Total Knee Arthroplasty: Practice Versus Publication.

BACKGROUND: Recent emphasis has been placed on nutritional status assessment prior to total knee arthroplasty (TKA), including multiple American Academy of Orthopaedic Surgeons publications recommending specific laboratory studies; however, the frequency with which surgeons obtain these laboratory studies remains unclear. We sought to assess the incidence of ordering nutritional laboratory studies in the 90 days prior to TKA, utilizing data from a large administrative claims database. METHODS: With use of the PearlDiver database, we identified 557,670 patients undergoing primary TKA from 2011 to 2020 with a metabolic panel or blood cell count claim within 90 days prior to TKA. We then determined the incidence of prealbumin, transferrin, vitamin D, and zinc laboratory tests claimed 90 days prior to TKA. Associations between claims and the year of surgery, patient demographics, and clinical characteristics were assessed by comparing proportions and chi-square testing. RESULTS: Nutritional laboratory studies were infrequently claimed within 90 days prior to TKA, with studies for prealbumin being performed in 2.2% of patients; transferrin, 1.9%; vitamin D, 10.2%; and zinc, 0.2%. From 2011 to 2020, there was a moderate but steady increase in the proportion of patients with claims for prealbumin (change from 0.8% in 2011 to 3.4% in 2020; p < 0.001), transferrin (0.8% to 2.7%; p < 0.001), and vitamin D (7.6% to 9.4%; p < 0.001) laboratory tests but there was less of a change for zinc (0.1% to 0.2%; p < 0.001). There were weak-to-absent associations of age, gender, obesity, diabetes, and anemia with laboratory claims. CONCLUSIONS: Despite multiple publications and recommendations, nutritional laboratory studies are infrequently ordered prior to TKA. Although there has been a slight increase in the use of nutritional laboratory studies over the past decade, patient factors such as gender and obesity were not associated with this increase. Understanding current practice patterns may help target future areas for improvement. LEVEL OF EVIDENCE: Diagnostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Time Required for Planned and Unplanned Episodes of Care in Aseptic Hip and Knee Revision Arthroplasty.

BACKGROUND: Studies indicate aseptic revision total hip arthroplasty (rTHA) and revision total knee arthroplasty (rTKA) requires much more effort but is reimbursed less than primary procedures per minute work time. This study quantified planned and unplanned work performed by the surgeon and/or their team during the entire episode of care "reimbursement window" and compared it to allowed reimbursement times by Centers for Medicare and Medicaid Services (CMS). METHODS: Between October, 2010, and December, 2020, all unilateral aseptic rTHA and rTKA procedures performed by a single surgeon at a single institution were retrospectively reviewed. Time dedicated to planned work was calculated from surgery scheduling to 90 days postoperative. Impromptu patient inquiries and treatments after discharge but within the episode of care, involving the surgeon/surgeon team constituted unplanned work. Planned and unplanned work minutes were summed and divided by the number of patients reviewed to obtain average minutes of work per patient. Work time was compared to CMS allowable times for rTHA (617 minutes) and rTKA (520 minutes). RESULTS: There were 292 Aseptic rTKA and 63 aseptic rTHA procedures included. Based upon CMS allowable times per patient there were a mean of 4.4 hours (267 minutes) of uncompensated care time per rTKA patient and a mean of 2.4 hours (141 minutes) of uncompensated care time per rTHA patient. CONCLUSION: Aseptic revisions are substantially more complex than primaries, requiring work effort that is not commensurate with current reimbursements. Financially disincentivizing surgeons to care for patients requiring revision surgery could reduce patient access to care when high quality care is needed the most.

Same-Day Discharge Following Aseptic Revision and Conversion Total Joint Arthroplasty: A Single-Institution Experience.

Background: With hospital inpatient capacity increasingly limited and primary total joint arthroplasty (TJA) rapidly transitioning to outpatient settings, the feasibility of outpatient aseptic revision and conversion TJA (rTJA) has been considered. Before the widespread adoption of outpatient rTJA, guidelines must be established to prevent patient harm. To this end, this study describes our initial experience with same-day-discharge (SDD) aseptic rTJA. Methods: All aseptic rTJAs performed between May 8, 2015, and December 30, 2021, were retrospectively reviewed. Revision indications, patient selection criteria, and outcomes including SDD success rate, predischarge complications, all-cause emergency department visits, inpatient readmissions, and unplanned clinic encounters within 90 days of surgery were recorded. Results: Thirty-five SDD aseptic rTJAs were performed. Conversion total hip arthroplasty (55.0%) and instability (27.3%) were the most common indications for hip revision. Instability (50%) and conversion total knee arthroplasty (20.8%) were most common for knee revision. SDD was achieved in 97% (34/35) of cases. One hip patient failed SDD due to persistent hypoxia requiring an overnight hospital stay and also underwent closed reduction for dislocation in the emergency department within 90 days of discharge. Two additional patients had unplanned clinic encounters within 90 days of the index procedure. There were no hospital readmissions or reoperations within 90 days. Conclusions: Our initial experience suggests SDD aseptic rTJA can be safe and effective when modern perioperative outpatient protocols and surgical techniques are implemented. Future studies should further define patient selection criteria to optimize outcomes and minimize complications in this population.

Time Required for Planned and Unplanned Episodes of Care in Septic Two-Stage Revision Hip and Knee Arthroplasty.

BACKGROUND: Septic revision total hip (rTHA) and knee (rTKA) arthroplasty requires more effort but is reimbursed less than primary procedures per minute of intraoperative time. This study quantified planned and unplanned work performed by the surgical team for septic 2-stage revision surgeries during the entire episode-of-care "reimbursement window" and compared that time to allowable reimbursement amounts. METHODS: Between October 2010 and December 2020 all unilateral septic 2-stage rTHA and rTKA procedures performed by a single surgeon at a single institution were retrospectively reviewed. Time dedicated to planned work was calculated over each episode of care, from surgery scheduling to 90 days postoperatively. Impromptu patient inquiries and treatments after discharge, but within the episode of care, involving the surgeon/surgeon team constituted unplanned work. Planned and unplanned work minutes were summed and divided by the number of patients reviewed to obtain average minutes of work per patient. RESULTS: Sixty-eight hips and 64 knees were included. For 2-stage rTHA and rTKA the average time per patient for planned care was 1728 and 1716 minutes and for unplanned care was 339 and 237 minutes. Compared to the Centers for Medicare and Medicaid Services' allowable reimbursement times, an additional 799 and 887 minutes of uncompensated time was required to care for 2-stage rTHA and rTKA patients. CONCLUSION: Two-stage revision procedures are substantially more complex than primary procedures. Financially disincentivizing surgeons to care for these patients reduces access to care when high-quality care is most needed. These findings support increasing the allowable times for 2-stage septic revision cases.

Complications and Outcomes Associated With a Novel, Prefabricated, Articulating Spacer for Two-Stage Periprosthetic Joint Infection Treatment.

BACKGROUND: Various prefabricated articulating spacer options have been described for 2-stage treatment of chronic periprosthetic joint infection, but their results are poorly generalizable between designs due to differing antibiotic and material properties. This study reports outcomes for a novel, prefabricated, commercially available cement-on-cement articulating spacer. METHODS: A retrospective review of prospectively collected data for patients undergoing treatment with a prefabricated articulating cement spacer was performed. Outcomes were categorized as spacer complications, reimplantation rates, function, reinfection, and mortality. RESULTS: Seventy-six knees and 28 hips were analyzed. Spacer survival free of fracture, instability, or other implant-related complication until reimplantation was 100%. There were no bony or spacer fractures during the interstage or reimplantation. Reimplantation occurred in 84.6% of resected joints. Following spacer implantation, all but 1 patient was allowed to bear weight. The proportion of patients requiring an assistive device decreased from 67% prior to resection to 31% following reimplantation. Knee flexion improved from an average of 88.1° before resection to 111.9° following reimplantation. Eighty-seven percent of cases were infection free at mean follow-up of 16.6 ± 10.4 months. CONCLUSION: Study results demonstrate that this novel, prefabricated, articulating antibiotic spacer is safe, allows for good interstage function, and results in reasonable infection eradication rates at early term follow-up. LEVEL OF EVIDENCE: Therapeutic Level III.

Comparison of Surgical Site Complications With Negative Pressure Wound Therapy vs Silver Impregnated Dressing in High-Risk Total Knee Arthroplasty Patients: A Matched Cohort Study.

BACKGROUND: Closed incision negative pressure wound therapy (ciNPWT) may reduce surgical site complications following total joint arthroplasty. Although unlikely necessary for all patients, the criteria for utilizing ciNPWT in primary total knee arthroplasty (TKA) remain poorly defined. This study's purpose was to compare the incidence of incisional wound complications, non-incisional complications (ie, dressing reactions), reoperations, and periprosthetic joint infections (PJIs) among a group of high-risk primary TKA patients treated with ciNPWT vs an occlusive silver impregnated dressing. METHODS: One hundred thirty high-risk primary TKA patients treated with ciNPWT were 1:1 propensity matched and compared to a historical control group treated with an occlusive silver impregnated dressing. High-risk criteria included the following: active tobacco use, diabetes mellitus, body mass index >35 kg/m2, autoimmune disease, chronic kidney disease, Staphylococcus aureus nasal colonization, and non-aspirin anticoagulation. RESULTS: Age, gender, and risk factor profile were comparable between cohorts. The ciNPWT cohort had significantly fewer incisional wound complications (6.9% vs 16.2%; P = .031) and significantly more non-incisional complications (16.9% vs 1.5%; P < .001). No dressing reactions required clinical intervention. There were no differences in reoperations or periprosthetic joint infections (P = 1.000). In multivariate analysis, occlusive silver impregnated dressings (odds ratio 2.9, 95% confidence interval 1.3-6.8, P = .012) and non-aspirin anticoagulation (odds ratio 2.5, 95% confidence interval 1.1-5.6, P = .028) were associated with the development of incisional wound complications. CONCLUSION: Among high-risk patients undergoing primary TKA, ciNPWT decreased incisional wound complications when compared to occlusive silver impregnated dressings, particularly among those receiving non-aspirin anticoagulation. Although an increase in dressing reactions was observed, the clinical impact was minimal.

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.

Time Required for Planned and Unplanned Episodes of Care in Primary Total Joint Arthroplasty: Has Anything Changed With a Growth in Outpatient Arthroplasty?

BACKGROUND: This study sought to determine the total amount of time committed to planned and unplanned episodes of care related to primary, unilateral total joint arthroplasty (TJA), relative to a growth in outpatient TJA. METHODS: All primary, unilateral TJA procedures performed over a 7-year period by a single surgeon at a single institution were retrospectively reviewed. Time dedicated to planned work was calculated over each episode of care, from surgery scheduling to 90 days postoperatively. All telephone inquiries and readmissions involving the surgeon's direct input, over the episode of care, constituted time dedicated to unplanned work. RESULTS: Between 2012 and 2018, as the proportion of outpatient TJAs increased, the average planned episode-of-care time per patient decreased from 412 minutes to 361 minutes. Despite a 108% increase in the total number of outpatient TJAs between 2017 and 2018 (51/432 (11.8%) to 106/555 (19.1%); P = .002), neither the average number of unplanned telephone inquiries (4.6 ± 3.8 vs 4.2 ± 3.7; P = .124), nor the mean time per patient required to respond to calls (23.1 ± 19.4 vs 21.2 ± 18 minutes, P = .135) differed. Between 2017 and 2018, the average total episode-of-care time per patient decreased from 403 minutes (376 planned + 27 unplanned) to 387 minutes (361 planned + 26 unplanned). CONCLUSION: Despite an increase in outpatient TJA, the average time required for planned and unplanned patient care remained relatively constant. The growth of outpatient TJA nationally should not trigger a change in Centers for Medicare and Medicaid Services benchmarks.

Total Knee Arthroplasty among Medicare Beneficiaries with Hemophilia A and B Is Associated with Increased Complications and Higher Costs.

Operations on patients with hemophilia A and B are complex. Studies evaluating postoperative outcomes and costs following total knee arthroplasty (TKA) in patients with hemophilia are limited. A retrospective review of the entire Medicare dataset from 2005 to 2014 was performed. International Classification of Disease 9th revision codes were used to identify patients with hemophilia A and B and they were matched to controls using a 1:1 random matching process based on age, gender, Charlson Comorbidity Index (CCI), and select comorbidity burden. The 90-day preoperative period was evaluated for comorbidities and the 90-day postoperative period was analyzed for outcomes and reimbursements. Logistic regression models were generated to compare outcomes between cases and controls. A total of 4,034 patients with hemophilia were identified as having undergone TKA. About 44.8% were between the ages of 65 and 74 and 62.4% were female. Although the CCI was identical in both cohorts, individual comorbidities not controlled for varied significantly. Medical complications were more frequent among the patients with hemophilia: postoperative bleeding (odds ratio [OR]: 1.7; 95% confidence interval [CI]: 1.2-2.3), deep venous thrombosis (OR: 2.3; 95% CI: 1.8-2.8), pulmonary embolism (OR: 2.9; 95% CI: 2.1-3.9), and blood transfusions (OR: 1.8; 95% CI: 1.6-1.9). Hemophilia was associated with higher odds of periprosthetic infection (1.78 vs. 0.98%, OR: 1.8 95% CI: 1.2-2.7). The 90-day reimbursements were higher for patients with hemophilia (mean: $22,249 vs. $13,017, p < 0.001). Medicare beneficiaries with a diagnosis of hemophilia experience more frequent postoperative complications and incur greater 90-day costs than matched controls following TKA. Surgeons should consider this when optimizing patients for TKA and payors should consider this for risk-adjusting payment models.

Mechanical performance and implications on bone healing of different screw configurations for plate fixation of diaphyseal tibia fractures: a computational study.

Diaphyseal tibia fractures may require plate fixation for proper healing to occur. Currently, there is no consensus on the number of screws required for proper fixation or the optimal placement of the screws within the plate. Mechanical stability of the construct is a leading criterion for choosing plate and screws configuration. However, number and location of screws have implications on the mechanical environment at the fracture site and, consequently, on bone healing response: The interfragmentary motion attained with a specific plate and screw construct may elicit mechano-transduction signals influencing cell-type differentiation, which in turn affects how well the fracture heals. This study investigated how different screw configurations affect mechanical performance of a tibia plate fixation construct. Three configurations of an eight-hole plate were considered with the fracture in the center of the plate: eight screws-screws at first, fourth, fifth and eighth hole and screws at first, third, sixth and eighth hole. Constructs' stiffness was compared through biomechanical tests on bone surrogates. A finite element model of tibia diaphyseal fracture was used to conduct a stress analysis on the implanted hardware. Finally, the potential for bone regeneration of each screw configuration was assessed via the computational model through the evaluation of the magnitude of mechano-transduction signals at the bone callus. The results of this study indicate that having screws at fourth and fifth holes represents a preferable configuration since it provides mechanical properties similar to those attained by the stiffest construct (eight screws), and elicits an ideal bone regenerative response.

Hospital Discharge Within a Day After Total Knee Arthroplasty Does Not Affect 1-Year Complications Compared With Rapid Discharge.

INTRODUCTION: In patients undergoing total knee arthroplasty (TKA), it is unclear whether a difference in complication rates exists between patients discharged the day of surgery compared with subsequent postoperative days. METHODS: Data were collected from the PearlDiver Patient Records Database from 2007 to 2017. Subjects were identified using International Classification of Diseases codes. Eligible patients were stratified into the following three groups: (1) same day discharge (<24 hours postoperatively), (2) rapid discharge (1 to 2 days), and (3) traditional discharge (3 to 4 days) based on the length of stay. RESULTS: In total, 84,864 patients were identified as having undergone primary TKA. The incidence of same day discharge, rapid discharge, and traditional discharge was 2.36% (2,004/84,864), 28.56% (24,235/84,864), and 69.08% (58,625/84,864), respectively. After adjustment, no notable differences were observed in the overall complication and revision rates between the same day discharge group and either the rapid discharge or the traditional discharge group. On multivariate analysis, patients in the rapid discharge cohort were less likely to require manipulation under anesthesia or develop periprosthetic joint infection when compared with the traditional discharge group at 1 year postoperatively. CONCLUSIONS: For those who qualify after careful selection, same day and rapid discharge TKA may be a feasible alternative to the traditional inpatient TKA. LEVEL OF EVIDENCE: A level 3 retrospective, prognostic study.

What Are the Benefits of Hip Resurfacing in Appropriate Patients? A Retrospective, Propensity Score-Matched Analysis.

BACKGROUND: Hip arthritis is one of the major causes of disability worldwide. Hip resurfacing arthroplasty (HRA) has emerged in recent years as an alternative to total hip arthroplasty (THA), but complications of HRA have limited the patient population to younger male patients with primary osteoarthritis and large hip anatomy. How the functional benefits of HRA in this population compare with those of THA is not entirely clear. QUESTIONS/PURPOSES: The primary aim of this study was to determine whether there were differences in hip disability and patient satisfaction with surgery between these two groups at 2 years after surgery, using patient-reported outcome measures (PROMs) and subjective measures of patient satisfaction. Additionally, we sought to determine whether there were differences in post-operative discharge disposition, revision rates, or adverse events. METHODS: We searched an institutional database to identify patients undergoing unilateral HRA or THA between January 2007 and July 2011 who met today's recommended criteria for HRA: younger male patients with large-enough hip anatomy to make surgery viable (a femoral head of at least 48 mm in HRA patients and, in THA patients, an acetabular shell size of 54 mm, the minimum outer shell size that could accommodate a femoral head component of 48 mm; for matching purposes, acetabular shell size in THA was used as a surrogate for the femoral head size used in HRA). We used propensity score matching to control for potentially confounding pre-operative variables and administered the Hip Disability and Osteoarthritis Outcome Score (HOOS) survey, including its subdomains, at the 2-year mark. We also assessed differences between groups in Lower Extremity Activity Scale scores, 12-item Short Form Health Survey results, and answers regarding satisfaction with surgery. We calculated minimal detectable change, minimum clinically important change, and substantial clinical benefit using anchor-based techniques for multiple outcome measures. RESULTS: There were 251 patients in each group. HRA patients scored significantly higher than THA patients on the 2-year HOOS sports and recreation (92 versus 87, respectively) and on rates of overall satisfaction (94% versus 89%, respectively). The HRA group also had a greater chance of achieving minimum clinically important change (18.75 points) in the HOOS sports and recreation subdomains than the THA group (97% versus 91%). No significant difference was found in 6-month adverse event rates. HRA patients also had a significantly shorter mean hospital stay, a higher rate of discharge to home, and a lower incidence of a "significant" limp after surgery. CONCLUSION: HRA may provide a functional benefit in sports and recreation and greater satisfaction in patients who meet the current criteria for HRA. Because these benefits may be small, pre-operative counseling should focus on balancing the possible functional benefits against the longer-term risks associated with metal-on-metal bearings.

Extensor Mechanism Reconstruction Using Marlex Mesh: Is Postoperative Casting Mandatory?

BACKGROUND: Extensor mechanism (EM) disruption after total knee arthroplasty is a catastrophic complication. Reconstruction using monofilament polypropylene mesh (Marlex Mesh; CR Bard, Franklin Lakes, NJ) has emerged as the preferred treatment, but reports are limited to the designing institution. This study describes a nondesigner experience and compares 2 postoperative immobilization strategies: long leg cast vs knee immobilizer. METHODS: A retrospective review of consecutive EM reconstructions between 2012 and 2019 was performed. Primary repairs and allograft reconstructions were excluded, leaving 33 knees (30 patients) who underwent Marlex reconstruction. Mean time from disruption to reconstruction was 14 months, and 14 of 33 (42%) had previous repair or reconstruction attempts. The mean age was 69 years, and mean body mass index was 35 kg/m2. Postoperatively, extension was maintained using a knee immobilizer in 19 of 33 (58%) patients, whereas 14 of 33 (42%) patients were long leg casted. Kaplan-Meier analysis determined all-cause survivorship free of mesh failure. RESULTS: At mean 25-month follow-up, 19 of 33 (58%) EM reconstructions were functioning. Excluding explanted infections (5 recurrent and 2 new), 19 of 26 (73%) EM reconstructions were in situ. Six-year survivorship was 69% and not influenced by immobilization type (cast: 67%, immobilizer: 71%; P = .74). Extensor lag was not associated with immobilization type, improving from a mean preoperative lag of 43° to a mean postoperative lag of 9°. Among successes, University of California at Los Angeles activity and Knee Injury and Osteoarthritis Outcome Score - Joint Replacement score improvements exceeded minimal clinically important difference (2.2-3.3 and 52.5-64.0, respectively). CONCLUSION: Marlex mesh EM reconstruction is a durable and reliable treatment with acceptable clinical results achievable outside the designer institution. Provided sufficient duration and compliance with postoperative immobilization, similar outcomes can be obtained with either a cast immobilizer or a knee immobilizer.

Enhanced Biomechanical Performance of a Modern Polyester Surgical Mesh for Extensor Mechanism Reconstruction in Total Knee Arthroplasty.

BACKGROUND: Extensor mechanism (EM) disruption following total knee arthroplasty is a devastating postoperative complication. Reconstruction with a synthetic mesh is one treatment option, although the optimal mesh material remains unknown. This study sought to compare the mechanical properties of 2 mesh material types that can be used for EM reconstruction. METHODS: Mechanical properties of a polypropylene mesh (Marlex mesh) and Ligament Advanced Reinforcement System (LARS) mesh were compared using force-displacement data from a material testing machine simulating knee movement during normal human gait. Tension to failure/ultimate tensile load, stiffness coefficients, axial strain, and cyclic hysteresis testing were measured and calculated. RESULTS: Compared to polypropylene mesh, LARS mesh demonstrated a significantly higher mean ultimate tensile load (2223 N vs 1245 N, P = .002) and stiffness coefficient (255 N/mm vs 14 N/mm, P = .035) in tension to failure testing, and significantly more energy dissipation (hysteresis) in hysteresis testing (771 kJ vs 23 kJ; P ≤ .040). LARS mesh also demonstrated significantly less maximum displacement compared to the polypropylene mesh (9.2 mm vs 90.4 mm; P ≤ .001). CONCLUSION: Compared to polypropylene mesh, LARS mesh showed superior performance related to force-displacement testing. The enhanced mechanical performance of LARS mesh may correlate clinically to fewer failures, increased longevity, and higher resistance to plastic deformation (extensor lag). Future research should evaluate survivorship and clinical outcomes of these meshes when used for EM reconstruction.

Primary Total Knee Arthroplasty Performed Using High-Viscosity Cement is Associated With Higher Odds of Revision for Aseptic Loosening.

BACKGROUND: Aseptic loosening (AL) is the most common reason for revision total knee arthroplasty (TKA). An association between high-viscosity cement (HVC) and AL has been suggested by small, uncontrolled, case series. This study sought to determine whether HVC use during primary TKA is independently associated with AL requiring revision. METHODS: We retrospectively analyzed a prospectively collected institutional knee registry to identify all primary TKAs from January 2007 to December 2016. Patients with less than 2 years of follow-up were excluded. Cement type was divided into 2 groups: HVC and low-viscosity cement. Potential confounders including age, body mass index, preoperative diagnosis, antibiotics in the cement, and implant type were recorded. Multivariable logistic regression analysis was used to determine whether HVC is independently associated with revision for AL. RESULTS: In total, 10,014 patients were included. Revision for AL was significantly higher in the HVC cohort (91/4790; 1.9%) vs the low-viscosity cement cohort (48/5224; 0.92%) (P < .001). Logistic regression demonstrated HVC to be independently associated with higher odds of revision for AL (odds ratio 2.26, 95% confidence interval 1.58-3.22, P < .001). Younger age was also associated with higher odds of revision for AL (odds ratio 0.96, 95% confidence interval 0.94-0.98, P < .001). Body mass index, gender, laterality, preoperative diagnosis, and antibiotics in the cement were not associated with revision for AL. Implant manufacturer, implant design, and cement brand all impacted the odds of undergoing revision for AL. CONCLUSION: Although HVC is an attractive option for use in primary TKA, this appropriately controlled study demonstrates higher odds of revision for AL when using HVC with multiple different implant types.

Body Mass Index Classification Is Independently Associated with Health-Related Quality of Life after Primary Total Knee Arthroplasty: An Institutional Registry-Based Study.

The purpose of this study was to compare the health-related quality of life (HRQoL) before and after successful total knee arthroplasty (TKA) across World Health Organization (WHO) body mass index (BMI) classifications. Through an institutional registry, patients with end-stage knee osteoarthritis who received elective primary unilateral TKA were identified and categorized based on WHO BMI classification. Age, gender, laterality, year of surgery, and Charlson-Deyo comorbidity index were recorded. The primary outcome was the EQ-5D-3L index and visual analog scale (VAS) at 2 years postoperatively. Inferential statistics and regression analyses were performed to determine associations between BMI classification and HRQoL. EQ-5D-3L index and VAS scores were significantly different across BMI classes, with higher scores in patients with lower BMI at baseline and at 2 years. There was no difference observed for the 2-year change in EQ-VAS scores between groups, but there was a statistically greater increase in index scores for more obese patients. In the regression analyses, there were statistically significant negative effect estimates for EQ-VAS and index scores associated with increasing BMI class, particularly for class III obesity. Higher BMI classification is independently associated with lower HRQoL scores 2 years after uncomplicated primary TKA, although obese patients experienced greater benefits in EQ-5D index scores following TKA. These results detail the relationship between BMI and HRQoL following TKA and suggest that preoperative weight loss may lead to improved outcomes following TKA, but also that obesity, alone, should not be a contraindication to TKA.

No Difference in Force Required for Intraprosthetic Dislocation of Mixed Manufacturer vs Same Manufacturer Dual Mobility Articulations.

BACKGROUND: To avoid the morbidity of removing well-fixed implants during revision surgery, the off-label practice of mixing femoral heads with dual mobility (DM) polyethylene liners from different manufacturers is commonly performed. The resistance to intraprosthetic dislocation, when the inner prosthetic head disengages from the polyethylene bearing, between mixed and same manufacturer constructs remains unknown. METHODS: Between January 2010 and July 2018, 168 DM liners were retrieved. Specimens were excluded for catastrophic wear (n = 14), previously levered-out (n = 17), and cases in legal proceedings (n = 8). Using a validated setup, 129 specimens were uniaxially loaded 100 mm from the femoral head until lever-out failure of the head from the liner. The difference in maximum lever-out force (LOF) was compared for same and mixed manufacturer retrievals (Student t-test). Multivariable regression analysis evaluated the influence of potential confounders (length of implantation, head size, head material, presence of skirt) on LOF. RESULTS: Ninety-seven same and 32 mixed manufacturer DM constructs were tested. The average LOF for same (272.6 ± 68.7 N) and mixed (299.2 ± 89.0 N) manufacturer specimens was not significantly different (P = .08). An inner head size of 22.2 mm was associated with 184.4-N increase in LOF (P < .001), the presence of a skirt was associated with 63.8-N increase in maximum LOF, and head material (ceramic vs metal) did not influence LOF. CONCLUSION: We found no difference in the force required to lever-out same and mixed manufacturer inner heads from DM liners, suggesting that mixing manufacturers when placing DM articulations on well-fixed femoral stems should not increase the risk of intraprosthetic instability.