Low Rate of Early Periprosthetic Fractures in Direct Anterior Total Hip Arthroplasty with a Triple-Tapered Wedge Stem.

INTRODUCTION: Utilization of the direct anterior approach (DAA) for total hip arthroplasty (THA) has been steadily increasing in recent years. While the DAA may offer some benefits compared to other approaches, there are still risks involved including relatively higher rates of periprosthetic femur fractures, especially when combined with cementless femoral stem use. The purpose of this study is to evaluate the early postoperative femoral complications with a short triple-wedge tapered stem used in primary THA via a DAA. MATERIALS AND METHODS: A retrospective review was conducted of the arthroplasty registry of our institution from April 2022 to August 2023 to identify patients who underwent a primary THA via a DAA with the Short Medacta Stem (SMS) (Medacta International, Castel San Pietro, Switzerland). Patients were excluded if the stem was used for a revision surgery, they were within 90 days of surgery, or they refused research consent. Inclusion criteria was met in 262 patients (302 hips). Data was collected after reviewing the chart, and reports and radiographic measurements, including Dorr type and canal fit ratios, were obtained from preoperative and postoperative radiographs, respectively. RESULTS: A total of 302 total hips were included, 161 patients were male (53.3%) and 141 were female (46.7%), with an average age of 66.5 years (27-88, +/- 10.7 years). Average follow up was 0.3 years (range, 0.05-1.71 years). The majority of patients had a Dorr B femur (81.7%). The Median stem size used was an 8 (range, 2-15), and 89.4% of those had a collar. Average canal fill ratio was 0.83 (range, 0.43-0.98, +/- 0.07). Overall, there were two Vancouver B2a periprosthetic femoral shaft fractures (0.66%) that required revision surgery to a modular stem. In addition, there were two Vancouver Ag greater trochanteric fractures (0.66%) with acceptable alignment that did not require revision surgery. Demographic information about the patients with femoral complications is summarized in Table I. Average age of patients with femoral complications was 69.5 years, with an average canal fit ratio of 0.88. CONCLUSION: We found that the triple-wedge implant had a low rate of early femoral complication in primary THA from an anterior approach and is safe for use in THA from a DAA. More follow up is needed to evaluate continuing implant survivorship and patient outcomes.

Use of a Smartphone-Based Care Platform After Primary Partial and Total Knee Arthroplasty: 1-Year Follow-Up of a Prospective Randomized Controlled Trial.

BACKGROUND: The rise in demand of knee arthroplasty has led the industry to develop methods to decrease costs of care, such as novel methods of delivering physiotherapy, including smartphone-based exercise educational platforms. The purpose of this study was to determine the noninferiority of one such system after primary knee arthroplasty as compared to traditional in-person physiotherapy. METHODS: A prospective, multicenter randomized clinical trial was conducted comparing standard of care rehabilitation to a smartphone-based care platform after primary knee arthroplasty from January 2019 to February 2020. One-year patient outcomes, satisfaction scores, and utilizations of health care resources were analyzed. A total of 401 patients was available for analysis-241 in the control and 160 in the treatment group. RESULTS: There were 194 (94.6%) patients in the control group who required 1 or more physiotherapy visits compared to only 97 (60.6%) patients in the treatment group (P < .001). Emergency department visits within 1 year occurred in 13 (5.4%) patients and 2 (1.3%) patients in the control and treatment groups, respectively (P = .03). The change in mean Knee Injury and Osteoarthritis Outcome Score for joint replacement scores at 1 year was similar between both the groups (32.1 ± 1 6.8 versus 30.1 ± 18.1, P = .32). CONCLUSION: Implementation of this smartphone/smart watch care platform showed similar outcomes to traditional care models at 1 year postoperative. Traditional physiotherapy and emergency department visits occurred at much lower rates in this cohort, which could alleviate the need for health care dollars spent by reducing postoperative costs and enhancing communication across the health care system.

Minimum 25-Year Results of a Tapered Titanium Porous Plasma Spray Coated Femoral Component.

BACKGROUND: Previous studies have reported excellent results with tapered, titanium, porous plasma-sprayed components in patients undergoing uncemented primary total hip arthroplasty (THA). The purpose of this study was to examine survival and clinical results at a minimum 25-year follow-up. METHODS: We reviewed all patients who underwent primary THA at our center through 1995 with a specific femoral component that was essentially unchanged since its 1984 introduction, except porous coating was continued circumferentially in 1987, a hydroxyapatite-coated option was offered in 1988, and an offset option was added in 1999. There were 332 patients (396 THA) who had a minimum 25-year follow-up (range, 25 to 37). Mean age at surgery was 48 years (range, 21 to 70 years). Mean follow-up in nonfailed patients was 29 years (range, 25 to 37 years). RESULTS: There were 31 femoral revisions (7.8%): 9 infections, 3 failures of ingrowth, 5 aseptic loosening, 8 osteolysis well-fixed, 2 periprosthetic fractures, 2 polyethylene wear with trochanteric avulsion, 1 component breakage, and 1 malalignment well-fixed. Kaplan-Meier survival with the endpoint of all-cause stem revision was 94.8% (95% confidence interval: ±0.9%) at 37 years, and with the endpoint of aseptic loosening/failure of ingrowth was 98.7% (95% confidence interval: ±0.5) at 37 years. Harris hip scores improved significantly from 43 preoperatively to 76 most recently. CONCLUSION: This tapered, titanium, porous plasma spray-coated femoral component continues to demonstrate high long-term survival with a low rate of femoral component revision for any reason or aseptic loosening/failure of ingrowth.

Impact of Proximal Tibial Varus Anatomy on Survivorship After Medial Unicondylar Knee Arthroplasty.

BACKGROUND: Precise indications for medial unicondylar knee arthroplasty (UKA) continue to be defined. It is unclear if patients who have proximal tibia vara should be considered candidates for UKA. The purpose of this study was to evaluate the impact of proximal tibial varus alignment on outcomes after UKA. METHODS: A retrospective review identified 2,416 patients (3,029 knees) who underwent mobile-bearing medial UKA with 2-year minimum follow-up or revision. Preoperative radiographs were evaluated, and medial proximal tibial angle (mPTA) was measured. Patients were grouped into two groups as follows: mPTA <80 degrees and mPTA ≥80 degrees. Analyses were performed on the impact of mPTA on clinical outcomes, all-cause revisions, and tibial failures. RESULTS: At a mean follow-up of 5 years (range, 0.5 years to 12.8 years), there was not a statistically significant difference in clinical outcomes nor increased risk for all-cause revision or tibial failure in patients who had an mPTA <80°. Mean mPTA in patients who had tibial failures was 82.5° and not significantly different than those who did not have a tibial failure (82.9°) (P = .289). Tibial failure rate in knees with an mPTA <80° was 2.2% and not significantly different than knees with an mPTA ≥80° at 1.4% (P = .211). The all-cause revision rate in knees with an mPTA <80° was 5.8% and was not significantly different than knees with an mPTA ≥80° at 4.9% (P = .492). CONCLUSION: Patients who have tibia vara are not at increased risk for tibial related or all-cause failure in medial UKA. This data may allow surgeons to increase their indications for medial UKA.

Custom Triflange Acetabular Components For Catastrophic Bone Loss: Minimum 5-Year Results.

INTRODUCTION: Custom acetabular components are an increasingly utilized reconstructive option in total hip arthroplasty for catastrophic bone loss and acetabular failure. The purpose of this study was to determine the survivorship of such components for reconstruction due to catastrophic bone loss at a minimum 5-year follow-up. METHODS: From August 2003 to July 2016, 64 patients (66 hips) underwent acetabular reconstruction with custom triflange components. All hips were classified as Paprosky 3B or 3C. Harris hip scores were analyzed. Overall survivorship was determined by survival analysis. RESULTS: Seventeen patients (18 hips) died prior to returning for 5-year follow-up. One presumed living patient was lost to contact, yielding a cohort of 46 patients (47 hips) who had minimum 5-year follow-up. The mean age was 65 years (range, 46 to 85), mean body mass index was 29.4 (range, 18 to 45), and 72% were women. Mean follow-up was 8 years (range, 5 to 16). There were 3 revisions of the triflange device (6.4%) due to infection. Survivorship to end point of triflange removal for any reason was 94.1% (95% confidence interval: ±3.4%) at a mean of 16 years. In the overall series (n = 66), there were 9 (13.6%) additional reoperations as follows: 5 incision and debridements, one open reduction internal fixation, two stem revisions for periprosthetic femoral fracture, and one head revision. Harris hip scores improved significantly from a mean of 41 points preoperatively to 64 points postoperatively. CONCLUSIONS: Custom acetabular triflange components represent a highly effective tool in a surgeon's armamentarium. These devices are extremely helpful in managing catastrophic bone loss and have a good mean 16-year survival.

15-Year Follow-Up of Mobile Bearing Medial Unicompartmental Knee Arthroplasty.

INTRODUCTION: Medial unicompartmental knee arthroplasty (UKA) is a successful treatment for antero-medial osteoarthritis. However, there are few published studies on the long-term survival of this procedure. The purpose of this study was to review the 15-year minimum outcomes and survival of a mobile-bearing medial UKA. METHODS: A retrospective review was performed between July 2004 and December 2006 of all patients who underwent a medial UKA eligible for a minimum of 15-year follow-up. The initial query revealed 299 patients (349 knees). One hundred-seventeen patients died or were lost to follow-up, leaving 182 patients (219 knees) for analyses. Clinical outcomes and survivorship were analyzed. RESULTS: There were 59 implant-related reoperations which occurred at a mean of 10 years (range, 0 to 16 years). The most common reasons for reoperation were arthritic progression (9.1%) and aseptic loosening (9.1%). The 10-year survival with revision to TKA was 89% (95% confidence interval: 86% to 92.4%), and the 15-year survival was 84.1% (95% confidence interval: 80.3% to 88%). There were no statistically significant differences in survival between sex, body mass index, and age. Patients who were not revised had statistically significant improvements in knee range of motion and Knee Society scores. CONCLUSIONS: This study found similar long-term survival of a medial mobile-bearing UKA to published total knee arthroplasty outcomes. The implant evaluated in this study has undergone subsequent improvements in instrumentation and design. Further analyses should be performed on the long-term outcomes of the current implant platform.

Is an "Outpatient Arthroplasty Risk Assessment Score" Needed for Predicting Safe Selection of Outpatient Arthroplasty Candidates?

BACKGROUND: Total joint arthroplasty is rapidly shifting to the outpatient space. One of the challenges of same-day discharge adoption has been determining which patients are suitable candidates. Risk assessment tools have been developed, including the Outpatient Arthroplasty Risk Assessment (OARA) score. The purpose of this study was to assess its predictive utility. METHODS: A retrospective review was performed on all total joint arthroplasties performed at a single ambulatory surgery center in 2018, yielding a cohort of 1,105 patients (1,332 arthroplasties). The institution's outpatient criteria required optimization of all medical conditions; if the patient had no failing organ, they were candidates for same-day discharge. OARA scores were calculated based on preoperative histories and physical examinations. Analyses were performed on the statistical utility of the OARA score in predicting successful same-day discharge. The mean age was 59 years (range, 27-82), the mean body mass index was 33.3 kg/m2 (range, 16-66), and 51.5% were women. A total of 45% of patients had one or more major comorbidity. RESULTS: There were 81.6% of patients who had an acceptable OARA score (<60). In addition, 97% of patients who had an "unacceptable" OARA score were successfully discharged the same day. There were 23 patients who required inpatient observation; of these, 7 (30.4%) had an OARA score ≥60. CONCLUSION: The OARA score was accurate in predicting patients who successfully had same-day discharge but poor at predicting who would not. This system is time consuming and may be too restrictive on which patients are candidates for outpatient arthroplasty. Surgeons may consider a more simplified criteria for outpatient arthroplasty.

The Viability of an Artificial Intelligence/Machine Learning Prediction Model to Determine Candidates for Knee Arthroplasty.

BACKGROUND: The purpose of this study is to assess the viability of a knee arthroplasty prediction model using 3-view X-rays that helps determine if patients with knee pain are candidates for total knee arthroplasty (TKA), unicompartmental knee arthroplasty (UKA), or are not arthroplasty candidates. METHODS: Analysis was performed using radiographic and surgical data from a high-volume joint replacement practice. The dataset included 3 different X-ray views (anterior-posterior, lateral, and sunrise) for 2,767 patients along with information of whether that patient underwent an arthroplasty surgery (UKA or TKA) or not. This resulted in a dataset including 8,301 images from 2,707 patients. This dataset was then split into a training set (70%) and holdout test set (30%). A computer vision model was trained using a transfer learning approach. The performance of the computer vision model was evaluated on the holdout test set. Accuracy and multiclass receiver operating characteristic area under curve was used to evaluate the performance of the model. RESULTS: The artificial intelligence model achieved an accuracy of 87.8% on the holdout test set and a quadratic Cohen's kappa score of 0.811. The multiclass receiver operating characteristic area under curve score for TKA was calculated to be 0.97; for UKA a score of 0.96 and for No Surgery a score of 0.98 was achieved. An accuracy of 93.8% was achieved for predicting Surgery versus No Surgery and 88% for TKA versus not TKA was achieved. CONCLUSION: The artificial intelligence/machine learning model demonstrated viability for predicting which patients are candidates for a UKA, TKA, or no surgical intervention.

Outcomes Vary by Pre-Operative Physical Activity Levels in Total Knee Arthroplasty Patients.

Physical activity (PA) is suggested to reduce osteoarthritis pain; however, it may be avoided by patients requiring arthroplasty. Our goal was to investigate objective and patient-reported outcomes as a function of pre-operative PA levels in patients undergoing total knee arthroplasty (TKA). A total of 1941 patients enrolled in a multicenter prospective cohort study investigating a smartphone-based care management platform for self-directed rehabilitation underwent TKA and were included in the analysis. Activity was categorized based on the cohort's step count quartiles into low, moderate, and high pre-operative PA. Pre-operative and post-operative pain, EQ5D5L, KOOS JR, and step counts were compared by ANOVA according to activity group. Pre-operative pain scores increased with the decreasing activity level (all, p < 0.05) and were most improved post-operatively in the low PA group. High PA patients demonstrated the smallest improvements in EQ-5D-5L and KOOS JR. Low and moderate PA patients increased physical activity by three months, reaching 176% and 104% of pre-operative steps; high PA patients did not return to full step counts by one year post-operatively. Patients undergoing TKA who present with higher levels of physical activity report lower levels of pain and higher function pre-operatively but appreciate less improvement up to one year post-operatively. These results may be helpful in appropriate counseling of patient expectations before TKA.

A Reamer by Another Number: What Do They Actually Measure?

Acetabular reamers are a mainstay in the preparation of the acetabulum in total hip arthroplasty. Many surgeons, however, have noticed a discrepancy in the preparation of the socket and the reported size of reamers during this crucial phase of the procedure. A cross-sectional study performed by measuring a variety of sets of acetabular reamers was performed. The results showed that 17 of 21 sizes (81%) measured at least 2mm less than their reported size. Given that these differences beget unintended consequences, the industry may consider replacing or sharpening reamers already in use or even switching to a single-use reamer model.

Influence of Kinematic Alignment on Soft Tissue Releasing and Manipulation Under Anesthesia Rates in Primary Total Knee Arthroplasty.

INTRODUCTION: Total knee arthroplasty (TKA) is typically performed to restore a neutral mechanical alignment. Recently, there has been increased interest in kinematic alignment to restore the patient's individual alignment. The purpose of this study is to determine if kinematic balancing reduces the need for intraoperative soft tissue releases and rates of manipulation under anesthesia compared to mechanical alignment. MATERIALS AND METHODS: A query was performed between January 2021 and July 2022 to identify all patients who underwent a primary TKA that was performed with kinematic alignment (KA), which revealed 97 patients (107 TKAs). A cohort of consecutive patients from the preceding six months was gathered of patients who underwent primary TKA with mechanical alignment (MA). This cohort consisted of 199 patients (223 TKAs), yielding a total study cohort of 296 patients (330 knees). Mean age was 64.7 years, mean body mass index (BMI) was 33.1 kg/m2, and 57.1% of patients were female. Rates of manipulation under anesthesia and intraoperative release status were analyzed. RESULTS: Average range of motion preoperatively improved from 108.9° to 114.4° in the KA group but decreased from 112.3° to 109.9° in the MA group at six weeks (p<0.0001). Three of 107 knees (2.8%) required an additional pie-crusting of the superficial MCL in the KA group, whereas 58 of 223 knees (26.0%) did in the MA group (p<0.0001). Three of 107 knees (2.8%) in the KA group and 24 of 223 knees (10.8%) in the MA group required MUA (p<0.0001). CONCLUSION: Kinematic alignment significantly reduced the need for intraoperative soft tissue releases and postoperative manipulation under anesthesia. Further studies of the influence of kinematic alignment on these outcomes across multiple surgeons should be performed and/or compared to mechanical alignment.

Early Outcomes of a Universal Femoral Component with an Ultracongruent Insert.

INTRODUCTION: A primary total knee arthroplasty (TKA) system was introduced with a modern universal femoral design with a wide range of size and constraint options to accommodate a variety of patient anatomy, while incorporating streamlined instrumentation for maximum operating room efficiency and economy. The purpose of this study is to review the early clinical outcomes and survivorship at minimum two-year follow up with this knee system. MATERIALS AND METHODS: From September 2015 to December 2019, 797 patients (1004 knees) underwent primary total knee arthroplasty (TKA) at our center with the TJO Klassic® Complete Primary Knee System (Total Joint Orthopedics Inc., Salt Lake City, Utah) with ultracongruent bearings and were available for study with minimum two-year follow up. All office and hospital records were reviewed for patient demographics, preoperative and postoperative clinical assessments, including range of motion, Knee Society Scores (KSS), University of California at Los Angeles (UCLA) activity scales, complications, and reoperations. RESULTS: Mean follow up was 3.1 years (range, 2-6; standard deviation [SD] ±1.0). There were 471 female patients (59%) and 326 male patients (41%). Mean age at surgery was 69.3 years and mean body mass index was 32.9kg/m2. An all-polyethylene tibial component was used in 305 knees (30.4%) while a modular titanium tibial baseplate with polyethylene insert was used in 699 (69.6%). The patella was left unresurfaced in 381 knees (37.9%). KS scores, including pain component, clinical, and functional, as well as UCLA scores, all improved significantly (p<0.001). Two patients (3 knees) underwent revision. One patient required two-staged revision for treatment of infection in both knees, and one patient required patellar revision for aseptic loosening. Kaplan-Meier survival at 6.2 years was 98.4% (95% CI: ±0.97%) to endpoint of revision of any part for any cause and 99.6% (95% CI: ±0.36%) to endpoint of aseptic revision. CONCLUSIONS: At early minimum two-year follow up, this modern universal complete knee system used with ultracongruent bearings demonstrates excellent clinical outcomes and survival.

Mid-Term Survival of Total Hip Arthroplasty in Patients Younger Than 55-year-old.

BACKGROUND: Survivorship of total hip arthroplasty (THA) in younger patients is concerning given the inverse relationship between age and lifetime risk for revision. The purpose of this study is to determine if risk of revision has improved for patients aged 55 years or younger who undergo primary THA using modern polyethylene liners. METHODS: A retrospective review identified 2,461 consented patients (2,814 hips) with minimum 2-year follow-up who underwent primary THA at our institution between September 2007 and August 2014 using components from a single manufacturer (Zimmer Biomet), all with vitamin E-infused highly crosslinked polyethylene acetabular inserts. There were 561 patients (643 THA; 23%) aged 55 or younger and 1,900 (2,171 THA; 77%) older than 55. RESULTS: Mean follow-up was 5.0 years for both groups. There were more male patients in the younger (55%) than older (41%) group. Body mass index (BMI) was higher in younger patients independent of gender. Improvement in Harris hip score (HHS) was similar between groups. Kaplan-Meier survival to endpoint of all cause revision was similar between groups at 12 years (P = .8808) with 97.5% (95% CI: ±0.7%) for younger versus 97.1% (95% CI: ±0.6%) for older patients. Most frequent reason for revision overall was periprosthetic femoral fracture (21; 0.75%); univariate analysis revealed risk factors were female gender (P = .28) and age ≥65 years (P = .012). CONCLUSION: Use of modern polyethylene, such as vitamin E-stabilized highly cross-linked, liners during THA may improve survivorship in younger patients undergoing THA. Younger patients undergoing primary THA with highly cross-linked polyethylene liners had no increased rate of revision at mid-term follow-up.

Improving Operating Room Efficiency with Single-Use Disposable Instruments for Total Knee Arthroplasty.

Many strategies have been employed to improve operating room efficiency when performing total knee arthroplasty. The goals of efficiency improvements are to decrease operative time and reduce healthcare expenses while providing patients the best quality surgical care. Single-use disposable instruments are one technique to accomplish efficiency. The authors describe their experience with a specific implant manufacturer's disposable single-use instruments for total knee arthroplasty and analyze the cost and time savings compared to traditional instrumentation. Single-use disposable instruments are a viable option to improve OR efficiency, decrease sterile processing burden, and ensure sterile instrumentation for total knee arthroplasty. Furthermore, cost savings can be realized based on an institution's sterile processing expenses and whether the manufacturer or facility covers the cost of the single-use instruments.

Correlation Between Patient-Reported "Happiness" With Knee Range of Motion and Objective Measurements in Primary Knee Arthroplasty.

BACKGROUND: The purpose of this study was to evaluate the correlation between objective knee range of motion (ROM) and patient "happiness" with knee ROM after total knee arthroplasty. METHODS: This was a retrospective review of all primary total knee arthroplasties from June through December 2019, yielding 902 patients (1,009 knees). Records were reviewed for knee ROM preoperatively and postoperatively at 6-week follow-up as well as whether patients self-reported being "Happy with their ROM" (HWROM). Clinical records were reviewed for documents ROM as well as manipulation under anesthesia (MUA). RESULTS: The mean preoperative ROM was 110 ± 16 degrees, and 40% of patients were happy with their ROM. Postoperatively, the mean ROM was 106 ± 13 degrees (P < .001), and 76% of patients were HWROM (P < .001). The mean change in knee ROM was (-) 5 ± 17 degrees. The mean postoperative ROM and change in ROM of patients who were HWROM after surgery were 109 ± 12 degrees and (-)2 ± 16 degrees. In patients not HWROM postoperatively, the mean ROM and change in ROM were 98 ± 14 degrees and (-)12 ± 18 degrees (P < .001). Patients with a lower preoperative ROM were statistically significantly more likely to have a positive change in their HWROM (f ratio = 41, P < .001). MUAs were performed in 7.2% of knees, and 28% of patients who underwent an MUA were HWROM before MUA. CONCLUSION: Early postoperative knee ROM was correlated with patient HWROM. However, further longer term follow-up and more detailed analysis of patient happiness with ROM are needed.

Midterm Outcomes of a Bicruciate-Retaining Compared With the Bicruciate-Sacrificing Knee System.

BACKGROUND: The purpose of this study is to report midterm outcomes and survivorship of a bicruciate retaining knee arthroplasty compared with a bicruciate sacrificing anterior stabilized knee arthroplasty. METHODS: A retrospective comparative cohort analysis was performed of all patients who underwent primary total knee arthroplasty with the bicruciate retaining (XP) knee arthroplasty compared with an anterior stabilized (AS) cruciate sacrificing bearing. The XP system was used in 195 knees and was compared with 1471 knees in which the AS bearing was used. Patients were included in analysis if they had minimum 2-year follow-up or had a revision at any point. Preoperative and postoperative range of motion, Knee Society Scores, complications, and reoperations were evaluated. Unpaired t-test and chi-square analysis were performed. Kaplan-Meier survival analysis was performed for all-cause and aseptic survival. RESULTS: At an average of 5.2-year follow-up, 22 (11.3%) XP knees had been revised, compared with 23 (1.6%) AS knees (P < .001). Nineteen (9.7%) XP knees were revised for aseptic tibial loosening; one (0.1%) of the AS knees was revised for the same (P < .001). Nineteen of the XR revision surgeries (86.4%) were for aseptic tibial loosening. Compared with AS knees, the XP knees had significantly lower improvement in range of motion (3.2 deg vs 2.2 deg, P < .001), Knee Society (KS) pain scores (39 vs 35.7, P = .014), KS clinical scores (52.4 vs 46, P < .001), and KS functional scores (20.9 vs 15.5, P = .01). CONCLUSION: The bicruciate retaining Vanguard XP Total Knee System demonstrated an unacceptably high rate of aseptic tibial loosening without conferring the benefit of improved postoperative function relative to other available bearings.

Survivorship of a Metal-on-Metal Total Hip Implant With Modular Titanium Adapter.

BACKGROUND: Use of metal-on-metal (MoM) articulations in total hip arthroplasty (THA) has sharply declined due to high failure rates from metal-related complications. Although certain MoM designs have demonstrated only 46% survival, not all MoM designs have performed the same. The purpose of this study is to evaluate mid-term to long-term survival of a specific MoM implant with a modular titanium taper adapter. METHODS: A retrospective review was performed on all patients who underwent primary THA at our center with the M2a-Magnum system (Zimmer Biomet, Warsaw, IN). Of 829 patients (956 hips) identified, 754 patients (869 hips) met inclusion criteria of signed research consent, minimum 2-year follow-up, and/or any revision surgery. RESULTS: Mean follow-up was 11.0 years (range 2-16; ±3.5). Mean cup angle of inclination was 42.8° (range 24°-70°, ±6.3°), with 88.0% reconstructed within the 40° ± 10° safe zone. There were 64 revisions (7.36%): 7 (0.81%) septic and 57 (6.56%) aseptic. Of those, 32 (3.68%) were adverse reactions to metal debris. Kaplan-Meier survival free of revision for all causes was 88.6% at 16 years (95% confidence interval 86.8-90.4). Univariate analysis of risk factors for all-cause, aseptic, and adverse reaction to metal debris revision found no relationship with female gender, age ≥65 years, body mass index >30 kg/m2, higher activity level, or inclination angle outlier. CONCLUSION: The results of this study demonstrate a more favorable mid-term to long-term survivorship with this specific MoM implant compared to other designs. Although our institution no longer performs MoM THA, further investigation into differences in MoM implant designs is warranted.

Fellow Involvement in Primary Total Knee Arthroplasty: Is There an "August Effect?"

The purpose of this study is to determine if a fellow's involvement, as well as duration of a fellow's training, impacts complications, outcomes, and survivorship in primary total knee arthroplasty (TKA). A retrospective review identified 2,790 consecutive patients (3,530 knees) who underwent primary TKA between 2003 and 2008. A 2-year minimum follow-up was available on 2,785 knees (2,195 patients). Operative data, clinical outcomes, complications, and survivorship were compared between cases with and without a fellow involved as well as comparing cases in the first quarter (Q1) of the academic year to the last three quarters (Q2-4). Mean follow-up was 9.7 years. Fellows were involved in 1,434 (41%) surgeries. Fellow cases had significantly longer tourniquet times (59.5 vs. 49 minutes, p < 0.001) and operative times (82.4 vs. 70.8 minutes, p < 0.001). Overall, there was no difference in clinical, functional, or pain outcomes between attending and fellow cases. Fellow cases during Q1 had significantly worse pain scores (p = 0.009) and clinical scores (p < 0.001). Revision rate, infection rates, and survivorship were not significantly different between fellow and attendings or during Q1 of fellowship compared with attendings. Primary TKA survivorship and complications were not affected by fellow involvement or academic quarter. An "August Effect" may be suggested for clinical and pain outcomes in the first 3 months of fellowship.

Use of Ion Beam Enhanced Deposition (IBED) Titanium Nitride for Knee Arthroplasty Implants.

INTRODUCTION: For much of recent history, the metal-bearing surface in total knee arthroplasty has not changed much, with cobalt-chromium being the most widely-used material. However, due to the presence of nickel in its composition, much research has been done to develop alternative metal-bearing surfaces for patients with metal sensitivity. Titanium nitride coatings have shown improved performance and resistance to abrasive wear when compared to their counterparts, thus making this material an ideal alternative to current implant technology. MATERIALS AND METHODS: Rigorous testing was undertaken to analyze the mechanical properties of titanium nitride for use as a coating in orthopedic implants, such as scratch adhesion, hardness, modulus, and wear rates with specialized machinery, including a Tribometer®, Nano Indenter® G200 (KLA Corporation, Milpitas, California), and scratch system. RESULTS: Across all properties tested-abrasive wear resistance, wear resistance, cohesive and adhesive failure load, hardness, and modulus-IBED TiN coatings were shown to be dominant to both uncoated CoCr and uncoated Ti-6Al-4V in a significant manner. CONCLUSION: The use of IBED TiN coatings offers a way to improve the performance of mechanical components, such as orthopedic implants made from Ti-6Al-4V materials. IBED TiN coatings can enable the use of Ti-6Al-4V as an alternative to CoCr for articulating orthopedic implant devices, such as knee arthroplasty.

Isolated Tibial Polyethylene Insert Exchange After Total Knee Arthroplasty for Treatment of Instability and/or Polyethylene Wear.

INTRODUCTION: Isolated tibial polyethylene insert exchange (ITPIE) as a treatment for instability and polyethylene wear after total knee arthroplasty (TKA) remains controversial with studies reporting varied results. The purpose of this study is to evaluate the survival and outcomes of ITPIE performed for treatment of instability with or without polyethylene wear after TKA. MATERIALS AND METHODS: A query of a private practice arthroplasty registry revealed 364 patients (390 knees) treated with ITPIE for instability and/or polyethylene wear after TKA between 1997 and 2019. Mean age was 66.8 years, mean body mass index (BMI) was 33.8 kg/m2, and 59% of patients were female. ITPIE for infection, tibiofemoral aseptic loosening, arthrofibrosis, poor wound healing, and extensor mechanism failure were excluded. All patients had well-fixed and well-aligned components prior to surgery. RESULTS: Mean follow up was 5.9 years. Knee Society Clinical (KSC) scores improved preoperatively from 55 to 76 postoperatively (p <0.001). Thirty knees (7.7%) required re-revision: 15 (3.8%) for ongoing instability, seven aseptic loosening, three infection, two patellofemoral maltracking, one patellar fracture, one metal allergy, and one revised elsewhere for cause unknown. Kaplan-Meier analysis revealed survival of 93.1% (95% CI: ±1.5%) at five years, 84.7% (95% CI: ±3.5%) at 10 years, and 80.5% (95% CI: ±4.4%) at 21 years. CONCLUSIONS: ITPIE is a reliable treatment for instability and/or polyethylene wear after TKA in the presence of well-fixed and well-aligned components with good survival and clinical improvement. The less invasive nature and reduced risk for bone loss make it an attractive option versus full revision.