Clinical and Biomechanical Evaluation of Mid-Level Constrained and Posterior-Stabilized Polyethylene Inserts in Primary Total Knee Arthroplasty: An Analysis of 12,674 Cases.

BACKGROUND: Mid-level constraint polyethylene designs provide additional stability in total knee arthroplasty (TKA). The purposes of this study were to (1) compare the survivorship and reason for revision between mid-level inserts and posterior-stabilized (PS) used in primary TKA and (2) evaluate the biomechanical constraint characteristics of mid-level inserts. METHODS: We reviewed all cases of primary TKA performed at our institution from 2016 to 2019 using either PS or mid-level constrained inserts from 1 of 6 manufacturers. Data elements included patient demographics, implants, reasons for revision, and whether a manipulation under anesthesia was performed. We performed finite element analyses to quantify the varus/valgus and axial-rotation constraint of each mid-level constrained insert. A one-to-one propensity score matching was conducted between the patients with mid-level and PS inserts to match for variables, which yielded 2 cohorts of 3,479 patients. RESULTS: For 9,163 PS and 3,511 mid-level TKAs, survivorship free from all-cause revision was estimated up to 5 years and was lower for mid-level than PS inserts (92.7 versus 94.1%, respectively, P = .004). When comparing each company's mid-level insert to the same manufacturer's PS insert, we found no differences in all-cause revision rates (P ≥ .91) or revisions for mechanical problems (P ≥ .97). Using propensity score matching between mid-level and PS groups, no significant differences were found in rates of manipulation under anesthesia (P = .72), all-cause revision (P = .12), revision for aseptic loosening (P = .07), and revision for instability (P = .45). Finite element modeling demonstrated a range in varus/valgus constraint from ±1.1 to >5°, and a range in axial-rotation constraint from ±1.5 to ±11.5° among mid-level inserts. CONCLUSIONS: Despite wide biomechanical variations in varus/valgus and axial-rotation constraint, we found minimal differences in early survivorship rates between PS and mid-level constrained knees.

Significantly Worse Fixation of Cemented Patellar Components on Multiacquisition Variable-Resonance Image Combination Magnetic Resonance Imaging Compared to Femoral and Tibial Components: A Cause for Concern?

BACKGROUND: The etiology of anterior knee pain after total knee arthroplasty (TKA) remains unclear. Few studies have examined patellar fixation quality. The purpose of the present study was to evaluate the patellar cement-bone interface after TKA on magnetic resonance imaging (MRI) and to correlate the patella fixation grade with the incidence of anterior knee pain. METHODS: We retrospectively reviewed 279 knees undergoing metal artifact reduction MRI for either anterior or generalized knee pain at least 6 months after cemented, posterior-stabilized TKA with patellar resurfacing with one implant manufacturer. MRI cement-bone interfaces and percent-integration of the patella, femur, and tibia were assessed by a fellowship-trained senior musculoskeletal radiologist. The grade and character of the patella interface were compared to the femur and tibia. Regression analyses were used to determine the association between patella integration with anterior knee pain. RESULTS: There were more patellar components with ≥75% zones of fibrous tissue (50%) compared to the femur (18%) or tibia (5%) (P < .001). There were a greater number of patellar implants with poor cement integration (18%) compared to the femur (1%) or tibia (1%) (P < .001). MRI findings showed more evidence of patellar component loosening (8%) compared to the femur (1%) or tibia (1%) (P < .001). Anterior knee pain was correlated with worse patella cement integration (P = .01), with women predicted to have better integration (P < .001). CONCLUSION: The quality of the patellar cement-bone interface after TKA is worse compared to the femoral or tibial component interface. Poor patellar cement-bone interface may be a source of anterior knee pain after TKA, but further investigation is required.

No Difference in the Rate of Periprosthetic Joint Infection in Patients Undergoing the Posterolateral Compared to the Direct Anterior Approach.

BACKGROUND: There remains inconsistent data about the association of surgical approach and periprosthetic joint infection (PJI). We sought to evaluate the risk of reoperation for superficial infection and PJI after primary total hip arthroplasty (THA) in a multivariate model. METHODS: We reviewed 16,500 primary THAs, collecting data on surgical approach and all reoperations within 1 year for superficial infection (n = 36) or PJI (n = 70). Considering superficial infection and PJI separately, we used Kaplan-Meier survivorship to assess survival free from reoperation and a Cox Proportional Hazards multivariate models to assess risk factors for reoperation. RESULTS: Between direct anterior approach (DAA) (N = 3,351) and PLA (N = 13,149) cohorts, rates of superficial infection (0.4 versus 0.2%) and PJI (0.3 versus 0.5%) were low and survivorship free from reoperation for superficial infection (99.6 versus 99.8%) and PJI (99.4 versus 99.7%) were excellent at both 1 and 2 years. The risk of developing superficial infection increased with high body mass index (BMI) (hazard ratio [HR] = 1.1 per unit increase, P = .003), DAA (HR = 2.7, P = .01), and smoking status (HR = 2.9, P = .03). The risk of developing PJI increased with the high BMI (HR = 1.04, P = .03), but not surgical approach (HR = 0.68, P = .3). CONCLUSION: In this study of 16,500 primary THAs, DAA was independently associated with an elevated risk of superficial infection reoperation compared to the PLA, but there was no association between surgical approach and PJI. An elevated patient BMI was the strongest risk factor for superficial infection and PJI in our cohort. LEVEL OF EVIDENCE: III, retrospective cohort study.

Outcomes After Revision Total Knee Arthroplasty From a Specific, Now-Recalled Implant System.

BACKGROUND: A specific total knee arthroplasty (TKA) implant system was recently recalled for high incidence of early polymeric wear and osteolysis. We analyzed the early outcomes of aseptic revision with these implants. METHODS: We identified 202 aseptic revision TKAs of this implant system performed at a single institution between 2010 and 2020. Revision indications included aseptic loosening (n = 120), instability (n = 55), and polymeric wear/osteolysis (n = 27). Components were revised in 145 cases (72%) and isolated polyethylene insert exchange occurred in 57 cases (28%). Kaplan-Meier and Cox proportional hazards analyses were used to determine survivorship free from all-cause rerevision and rerevision risk factors. RESULTS: At 2 and 5 years, survivorship free from all-cause rerevision was 89 and 76% in the polyethylene exchange cohort versus 92 and 84% in the component revision cohort (P = .5). At 2 and 5 years, survivorship in revision with components from the same manufacturer was 89 and 80% compared to 95 and 86% in revision with components from a different manufacturer (P = .2). Among re-revisions (n = 30), cones (37%), sleeves (7%), hinge/distal femoral replacement implants were frequently used (13%). Men had increased risk for rerevision (hazard ratio = 2.3, P = .04). CONCLUSION: In this series of aseptic revision TKAs performed on a now-recalled implant system, survivorship free from rerevision was lower than expected when components from the same manufacturer were utilized, but comparable to contemporary reports when both the components were revised with an alternative implant system. Metaphyseal fixation with cones and sleeves as well as highly constrained implants was frequently utilized at time of rerevision TKA. LEVEL OF EVIDENCE: Level IV.

Highly cross-linked polyethylene in primary total knee arthroplasty is associated with a lower rate of revision for aseptic loosening: a meta-analysis of 962,467 cases.

BACKGROUND: The evolution in total knee arthroplasty (TKA) includes the highly cross-linked polyethylene (HXLPE) which has been reported as an effective manner to reduce the wear of the polyethylene and the osteolysis. The purpose of the present study is to synthesize the results of comparative studies between HXLPE and conventional polyethylenes and determine their effect in primary TKA. METHODS: The US National Library of Medicine (PubMed/MEDLINE) and the Cochrane Database of Systematic Reviews were queried for publications utilizing the following keywords: "cross-linked", "polyethylene", "HXLPE", "conventional", "total knee arthroplasty", "TKA", "total knee replacement" and "TKR" combined with Boolean operators AND and OR. RESULTS: Ten studies met the inclusion criteria and were included in the present meta-analysis with 962,467 patients. No significant difference was found regarding the revision rate for any reason between the patients who received HXLPE and those with conventional liner (OR 0.67; 95% CI 0.39-1.18; I2: 97.7%). In addition, there was no difference regarding the radiolucent lines between the two types of liners (OR 0.54; 95% CI 0.20-1.49; I2: 69.4%). However, with data coming from seven studies enrolling a total of 411,543 patients, it was demonstrated that patients who received HXLPE were less likely to be revised due to aseptic loosening compared to the patients with conventional liners (OR 0.35; 95% CI 0.31-0.39; I2: 0.0%). CONCLUSION: The present meta-analysis showed that regarding the overall revision rate and radiographic outcomes there was no significant difference between the two types of liners. On the other hand, the significantly less revision rate due to loosening supports the routine continued use of HXLPE in primary TKA.

Two-Stage Revision Total Hip Arthroplasty With a Specific Articulating Antibiotic Spacer Design: Reliable Periprosthetic Joint Infection Eradication and Functional Improvement.

BACKGROUND: Two-stage revision utilizing spacers loaded with high-dose antibiotic cement prior to reimplantation remains the gold standard for treatment of periprosthetic joint infections (PJI) in total hip arthroplasty (THA) in North America, but there is a paucity of data on mid-term outcomes. We sought to analyze the survivorship free of infection, clinical outcomes, and complications of a specific articulating spacer utilized during 2-stage revision. METHODS: One hundred thirty-five hips (131 patients) undergoing a 2-stage revision THA for PJI with a specific articulating antibiotic spacer design from 2005 to 2013 were retrospectively reviewed. Infections were classified according to the Musculoskeletal Infection Society criteria. Mean age at resection was 65 years and mean follow-up was 5 years (rang, 2-10). RESULTS: Survivorship free of any infection after reimplantation was 92% and 88% at 2 and 5 years, respectively. Patients with a host-extremity grade of C3 compared to all patients with a host grade of A [hazard ratio (HR) 4.1, P = .05] were significant risk factors for poorer infection-free survivorship after reimplantation. Harris hip scores improved from a mean of 58 to a mean of 71 in the spacer phase (P = .002) and a mean of 81 post-reimplantation (P = .001). Fourteen (10%) patients dislocated after reimplantation, 9 (7%) of which required re-revision. Trochanteric deficiency (HR 19, P < .0001), dislocation of the articulating spacer prior to reimplantation [which occurred in 7 (5%) patients, 5 of whom subsequently dislocated the definitive implant] (HR 16, P < .0001), and female gender (HR 5, P = .002) were significant risk factors for post-reimplantation dislocation. CONCLUSION: Insertion of an articulating antibiotic spacer during a 2-stage revision THA for PJI demonstrates reliable infection eradication and improvement in clinical function, including the spacer phase. Patients with trochanteric deficiency and an articulating spacer dislocation are at high risk of post-reimplantation dislocation; judicial use of a dual-mobility or constrained device should be considered in these patients.

Cementation of a Dual Mobility Construct in Recurrently Dislocating and High Risk Patients Undergoing Revision Total Arthroplasty.

BACKGROUND: Recurrent instability remains a challenge after revision total hip arthroplasty (THA). We report the outcomes of cementing a cementless dual mobility (DM) component into a stable acetabular shell for the treatment and/or prevention of instability in revision THA. METHODS: Eighteen patients (18 THAs) undergoing revision THA with a specific monoblock DM construct cemented into a new acetabular component or an existing well-fixed component from 2011 to 2014 were retrospectively reviewed. Tumor prostheses and total femoral replacements were excluded. In 9 patients (50%), components were implanted specifically for recurrent dislocations. Mean age was 64 years; mean follow-up was 3 years. Patients underwent an average of 4 prior hip operations (range 2-6). RESULTS: No cemented DM cups dissociated at the cement-cup interface. Three patients (17%) experienced a postoperative dislocation. One required a revision to constrained liner and 2 underwent open reduction with retention of the DM construct. Harris Hip Scores improved from 53 to 82 postoperatively (P < .001). CONCLUSION: Cementation of a monoblock cup DM construct, an off-label use as the construct is not specifically made for cementation, into a well-fixed acetabular component provides an alternative to enhance prosthetic stability in (1) recurrently dislocating THAs with well fixed, well-positioned acetabular components and (2) complex acetabular reconstructions in which constraint should be avoided. While not a perfect solution in this series, DM constructs provide a number of advantages including no added constraint at the interface and a large effective femoral head to diminish prosthetic impingement.

A Novel Percentage-Based System for Determining Aseptic Loosening of Total Knee Arthroplasty Tibial Components.

BACKGROUND: There are limited data on evaluating the significance of radiolucent lines and aseptic loosening in total knee arthroplasty (TKA). We sought to compare the sensitivity, specificity, and reliability of the Knee Society Total Knee Arthroplasty Roentgenographic Evaluation and Scoring System (KSRES) in detecting tibial component loosening compared to a novel percentage-based system (PBS). METHODS: We retrospectively reviewed radiographs obtained from 48 patients within 6 months prior to revision TKA. The radiographs were randomized and four reviewers independently used the KSRES to categorize tibial implants as nonconcerning, clinical follow-up for progression, or loose as described by KSRES. For the PBS, the percent involvement of the tibial implant interface of any radiolucency at the bone-cement or cement-implant interface was determined. The higher percentage from either the anteroposterior or the lateral image was the final score. Components were categorized as nonconcerning (≤10%), clinical follow-up for progression (11%-24%), or loose (≥25%). We compared the sensitivity, specificity, and interobserver reliability using intraoperative assessment of implant fixation as the gold standard. RESULTS: For the KSRES, the mean sensitivity for determining tibial loosening was 7.3% and mean specificity for determining a nonconcerning implant was 95.9%. The PBS significantly increased the sensitivity to 91.1% (P < .001) while maintaining a specificity of 87.9% (P = .2). Interobserver reliability significantly increased from a mean kappa of 0.26 to 0.75 (P < .001). CONCLUSION: The KSRES significantly underestimates implant loosening. The proposed percentage-based system demonstrated excellent sensitivity, specificity, and interobserver reliability in determining tibial implant loosening in this patient population.

Characterizing the Diagnosis and Treatment of Allergic Contact Dermatitis to 2-Octyl Cyanoacrylate Used for Skin Closure in Elective Orthopedic Surgery.

BACKGROUND: While studies have shown that postoperative wound complications can predispose to deep infection following orthopedic surgery, the best form of skin closure has not been elucidated. Furthermore, the unique risks and benefits of each type of wound closure have not been studied. The goal of this study is to present the diagnosis and treatment of patients with allergic contact dermatitis (ACD) from 2-octyl cyanoacrylate, a skin adhesive commonly used in wound closure. METHODS: Twenty-nine patients with ACD to 2-octyl cyanoacrylate (Prineo, Ethicon, NJ) following elective orthopedic surgeries from 2013 to 2016 were retrospectively reviewed; this occurred in 29 of 6088 units of Prineo used at our institution, for an estimated incidence of 0.5%. Nineteen patients (66%) had knee operations. Mean age was 55 years (range, 15-92 years). We classified patients by symptom severity and treatment requirements into mild, moderate, and severe reactions. RESULTS: Most reactions were moderate (48%) or severe (38%) reactions. Mean time from surgery to diagnosis was 11.8 days (range, 2-42 days). All patients underwent removal of the Prineo dressing and daily dressing changes with a specific protocol. Twenty patients (69%) received oral antihistamines, 16 patients (55%) required topical corticosteroids, and 5 patients (17%) required oral corticosteroids. All cases of ACD ultimately resolved at a mean of 22 days (range, 13-56 days) postoperatively. CONCLUSION: 2-Octyl cyanoacrylate skin adhesive occurs in an estimated 0.5% of cases and can lead to severe postoperative ACD when used following orthopedic operations. However, with early recognition and appropriate treatment, patients' symptoms resolve without a significant impact on wound healing.

Mid-term survivorship of primary total knee arthroplasty with a specific implant.

The purpose of this study was to assess mid-term survivorship following primary total knee arthroplasty (TKA) with Optetrak Logic components and identify the most common revision indications at a single institution. We identified a retrospective cohort of 7,941 Optetrak primary TKAs performed from January 2010 to December 2018. We reviewed the intraoperative findings of 369 TKAs that required revision TKA from January 2010 to December 2021 and the details of the revision implants used. Kaplan-Meier analysis was used to determine survivorship. Cox regression analysis was used to examine the impact of patient variables and year of implantation on survival time. The estimated survivorship free of all-cause revision was 98% (95% confidence interval (CI) 97% to 98%), 95% (95% CI 95% to 96%), and 86% (95% CI 83% to 88%) at two, five, and ten years, respectively. In 209/369 revisions there was a consistent constellation of findings with varying severity that included polyethylene wear and associated synovitis, osteolysis, and component loosening. This failure mode, which we refer to as aseptic mechanical failure, was the most common revision indication. The mean time from primary TKA to revision for aseptic mechanical failure was five years (5 months to 11 years). In this series of nearly 8,000 primary TKAs performed with a specific implant, we identified a lower-than-expected mid-term survivorship and a high number of revisions with a unique presentation. This study, along with the recent recall of the implant, confirms the need for frequent monitoring of patients with Optetrak TKAs given the incidence of polyethylene failure, osteolysis, and component loosening.