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.

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.

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.

2021 Mark Coventry Award: Use of a smartphone-based care platform after primary partial and total knee arthroplasty: a prospective randomized controlled trial.

AIMS: The purpose is to determine the non-inferiority of a smartphone-based exercise educational care management system after primary knee arthroplasty compared with a traditional in-person physiotherapy rehabilitation model. METHODS: A multicentre prospective randomized controlled trial was conducted evaluating the use of a smartphone-based care management system for primary total knee arthroplasty (TKA) and partial knee arthroplasty (PKA). Patients in the control group (n = 244) received the respective institution's standard of care with formal physiotherapy. The treatment group (n = 208) were provided a smartwatch and smartphone application. Early outcomes assessed included 90-day knee range of movement, EuroQoL five-dimension five-level score, Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS JR) score, 30-day single leg stance (SLS) time, Time up and Go (TUG) time, and need for manipulation under anaesthesia (MUA). RESULTS: Overall, 90-day mean flexion was not significantly different between the control (121° (SD 11.7°)) and treatment groups (121o; p = 0.559); 90-day mean SLS was 22.7 seconds (SD 9.8) in controls and 24.3 seconds (SD 20.8) in treatment (p = 0.519); 90-day mean TUG times were 10.1 seconds (SD 4.8) in control and 9.3 seconds (SD 3.3) in treatment (p = 0.139). Mean KOOS JR scores were significantly different between control group (73.6 (SD 13.4)) and treatment group (70.4 (SD 12.6); p = 0.026). MUAs were performed in nine (3.7%) patients in the control group and four (1.9%) in the treatment group (p = 0.398). Physiotherapy was performed by 230 (94.4%) of control group and 123 (59.3%) of treatment group (p < 0.001). There were no significant differences between groups in postoperative urgent care visits, or readmissions within 90 days, with significantly fewer emergency department visits in the treatment group (16 (8.2%) vs five (2.5%), p = 0.014). CONCLUSION: The use of the smartwatch/smartphone care platform demonstrated non-inferiority of clinically significant outcomes to traditional care models, while requiring significantly less postoperative physiotherapy and fewer emergency department visits. This platform could aid in decreasing postoperative costs, while improving patient engagement and communication with the healthcare team. Cite this article: Bone Joint J 2021;103-B(6 Supple A):3-12.

Mid-Term Clinical Outcomes and Survivorship of a Second-Generation Modular Revision Knee System.

INTRODUCTION: Revision knee systems have adapted to the challenges of revision knee arthroplasty with offset stems, augments, cones, and various levels of constraint. The purpose of this study is to review the mid-term outcomes of a second-generation modular knee revision system. MATERIALS AND METHODS: A retrospective review was conducted from 2011 through 2014 on all patients who underwent knee arthroplasty with the Vanguard® 360 revision knee system (Zimmer Biomet, Warsaw, Indiana). Patients were included in the study if they were eligible for five-year minimum follow up and had signed a general research consent. The initial query revealed 253 patients (267 knees) that met inclusion criteria. Complications assessed were manipulation under anesthesia (MUA) and revision of any component. Statistical analysis using paired t-test was performed to evaluate changes in clinical outcomes and Kaplan-Meier survival analysis. RESULTS: Mean follow up was 6.6 years. The Vanguard® 360 knee system was used in four (1.5%) primary total knee arthroplasties (TKAs), 66 (24.7%) second-stage reimplantation TKAs after infection, and 197 (73.8%) aseptic revisions. There were significant improvements in knee range of motion and Knee Society Scores (all p<0.05). Manipulations under anesthesia were performed in 17 knees (6.4%). A total of 41 knees (15.4%) failed for any cause and required re-revision surgery. Of these, 11 (4.1%) failed due to aseptic loosening. Kaplan-Meier analysis revealed overall survival to endpoint of aseptic loosening to be 96.4% (95% CI: ±1.2%) at five years and 95.2% (95% CI: ±1.4%) at 9.5 years. When comparing survivorship in patients who underwent initial revision for aseptic indications compared with those whose underwent revision for second-stage reimplantation after infection, Kaplan-Meier survival to endpoint of revision for any cause at 9.5 years was higher for patients with aseptic than septic indication for TKA (87.0% [95% CI: ±2.4%] vs. 75.3% [95% CI: ±5.4%], p=0.0156). CONCLUSION: The findings of this study demonstrate greater than 95% aseptic survivorship with the use of the Vanguard® revision knee system at mid-term follow up.

Impact of Polyethylene Thickness on Clinical Outcomes and Survivorship in Medial Mobile-Bearing Unicondylar Knee Arthroplasty.

BACKGROUND: The thickness of the polyethylene bearing in medial unicondylar knee arthroplasty (UKA) is determined by the depth of the tibial resection, degree of correctable deformity, and balance of the knee. The purpose of this study is to evaluate whether polyethylene thickness in medial mobile-bearing UKA impacts clinical outcomes and survivorship. METHODS: A retrospective review from 2004 to 2017 identified patients who underwent a primary mobile-bearing medial UKA with 2-year minimum follow-up or revision. A total of 2305 patients (3030 knees) met inclusion criteria. Patients were divided in 2 groups: thin bearing (group 1): 3-mm or 4-mm bearing and thick bearing (group 2): ≥ 5 mm. The thin group consisted of 2640 knees (87%), whereas the thick group had 390 knees (13%). Preoperative and postoperative demographics, range of motion, Knee Society scores, complications, and reoperations were evaluated. RESULTS: Mean follow-up was 5.2 years (range, 0.5 to 12.6). There was no significant difference between groups in postoperative range of motion or Knee Society scores (P > .05). Manipulations were performed in 1.3% of patients and not significantly different between groups. The all-cause revision rate for group 1 was 4.02% and group 2 was 4.58% (P = .6). Revision rates for tibial aseptic loosening were significantly higher in group 2 (1.8%) than those in group 1 (0.7%) (P = .04). There was no significant difference in failure rates between groups for tibial collapse or fracture, femoral aseptic loosening, arthritic progression, bearing dislocation, or other cause of revision. CONCLUSION: This study demonstrated that thicker bearings in medial UKA increased the risk of tibial aseptic loosening, but not all-cause failures or clinical outcomes.

Interval Between Staged Bilateral Total Knee Arthroplasties Does Not Affect Early Medical or Surgical Complications.

BACKGROUND: The purpose of this study is to evaluate early postoperative surgical and medical complications in patients undergoing staged bilateral total knee arthroplasty (TKA) and determine if the interval to the second stage influences the risk of complications. METHODS: A retrospective review was performed from 2016 through 2018 of all staged bilateral primary TKA procedures, yielding a cohort of 1005 patients (2010 TKAs). Four groups were created based on the timing of the second stage: 3 to 6 weeks, 7 to 12 weeks, 13 to 24 weeks, and >24 weeks. Clinical data compared between groups included demographics, knee range of motion, University of California, Los Angeles (UCLA) activity score, Knee Society pain score, Knee Society clinical score, and Knee Society functional score. Postoperative complications within 90 days were evaluated, with complications after the second knee being the primary outcome. RESULTS: The mean follow-up after second stage was 10.7 months (range, 3 to 37 months). No significant differences were found between groups in the range of motion, Knee Society pain, Knee Society clinical score, Knee Society functional score, or University of California Los Angeles activity score in either the first or second knee. After the first knee surgery, medical complications were highest in the >24-week group. After the second knee, there were no significant difference in manipulation (P = .9), wound complications (P = .7), venous thromboembolism (P = .8), or other medical complications (P = 1) based on the interval duration. CONCLUSION: The interval between staged TKA did not affect early medical or surgical complications after the second stage. Early clinical and function results were not different based on timing of the second surgery.

Midterm Outcomes and Survivorship of Anterior Stabilized Versus Cruciate Retaining Bearing in Primary Total Knee Arthroplasty.

BACKGROUND: There has been increasing utilization of ultracongruent bearings with a cruciate retaining (CR) femoral component in primary total knee arthroplasty. The purpose of this study is to compare outcomes and survivorship between an ultracongruent anterior stabilized (AS) and CR bearing. METHODS: A retrospective review was performed from 2010 through 2014 of all primary total knee arthroplasties with a single knee systems identical CR femur and AS or CR bearing with minimum 2-year follow-up yielding a study cohort of 3323 patients (4164 knees). Knee range of motion, Knee Society pain scores, Knee Society clinical scores, Knee Society functional scores, and University of California Los Angeles activity scores were evaluated. The need for manipulation under anesthesia (MUA), nonrevision surgery and revisions were assessed. RESULTS: AS bearing was used in 1471 knees (35%) and CR bearing used in 2693 knees (65%). Mean follow-up was 5.4 years. The AS group had significantly higher improvements in knee range of motion, Knee Society clinical, Knee Society functional, and Knee Society pain scores. MUAs were performed on 120 knees (8.2%) in the AS group compared with 158 knees (5.9%) in the CR group (P = .005). The AS group had significantly less all-cause failure, aseptic failures, revisions for instability, and revisions for isolated polyethylene wear. The 10-year aseptic survival for AS was 98.3% and for 92.3% for the CR group (P = .002). CONCLUSION: These mid-term results demonstrate the AS bearing had significantly higher improvements in clinical and functional outcomes as well as greater survivorship. Knees in which an AS bearing was used did have a higher incidence of MUA.

Early Outcomes of an Alternative Bearing Surface in Primary Total Knee Arthroplasty in Patients with Self-reported Metal Allergy.

BACKGROUND: Most implants for total knee arthroplasty (TKA) are comprised of alloys that contain nickel. Controversy exists whether metal allergies produce negative effects and affect clinical outcomes. The purpose of this study was to retrospectively review a minimum 2-year follow-up with an ion-bombarded titanium TKA implant in patients with reported metal sensitivity. METHODS: A retrospective review of patients who underwent primary TKA with the ion-bombarded titanium Vanguard (Zimmer Biomet, Warsaw, IN) implant with 2-year minimum follow-up was performed from 2008 through 2017. The query revealed 346 patients (451 knees) with minimum 2-year follow-up. The mean age was 64.7 years, the mean body mass index was 35.1 kg/m2, and 95% of patients were women. RESULTS: The mean follow-up was 4.6 years. The mean range of motion improved from 109° to 112° (P = .03), University of California Los Angeles activity scale from 4.1 to 5.1 (P < .001), Knee Society Clinical scores from 36 to 89 (P < .001), and Knee Society Functional scores from 48 to 73 (P < .001). There were 5 (1.1%) revisions: 2 infections (2-staged exchange), 1 tibial revision for aseptic loosening after a fall, and 2 bearing exchanges for instability. Other surgeries were open reduction internal fixation of periprosthetic fracture, 1 arthroscopic release of snapping popliteus, and 4 local wound incision and debridement (2 superficial infections and 2 nonhealing wounds). Manipulation under anesthesia was required in 27 (6%) patients. CONCLUSIONS: These early results are encouraging for the use of alternative metal titanium alloy implants in metal-sensitive patients undergoing primary TKA. At 4.6 years of mean follow-up, patients had substantial improvement in the range of motion and clinical outcomes with a low frequency of revision.

Ambulatory Portable Pneumatic Compression Device as Part of a Multimodal Aspirin-Based Approach in Prevention of Venous Thromboembolism in Outpatient Total Knee Arthroplasty.

BACKGROUND: The purpose of this study is to review the incidence of symptomatic venous thromboembolism (VTE) in patients undergoing outpatient primary total knee arthroplasty (TKA) who used a portable pneumatic compression device as part of their VTE prophylaxis protocol. METHODS: A retrospective review of all outpatient primary TKA procedures in which patients used ambulatory pneumatic compression pumps as part of their multimodal VTE prophylaxis was performed from 2016 through 2018. This yielded a cohort of 1131 patients (1453 TKAs). An aspirin (ASA)-based protocol was used in patients with standard VTE risk receiving either 81 mg or 325 mg of ASA twice daily for 6 weeks postoperatively. High-risk patients received a stronger chemoprophylaxis for 2 weeks followed by ASA for 4 weeks. Pneumatic compression pumps were worn for 23 hours/day for 14 days. RESULTS: VTE prophylaxis medication was 81-mg ASA in 56% of patients, 325-mg ASA in 10% of patients, and stronger chemoprophylaxis in 34% of patients. Patients were considered morbidly obese (body mass index >40 kg/m2) in 267 (18.4%) procedures. Ninety-seven (6.7%) patients had a preoperative history of VTE event. Forty-nine duplex ultrasounds were performed (3.3% of TKAs). Confirmed VTE events were documented in only 5 (0.3%) patients. All VTEs occurred in high-risk patients who were discharged on stronger chemoprophylaxis. The time (days) to VTE was 3, 3, 7, 45, and 88 days. CONCLUSION: The use of portable pneumatic compression pumps as part of a multimodal VTE prophylaxis protocol aided in a very low rate of symptomatic VTE events in patients undergoing outpatient primary TKA.

Impact of Morbid Obesity on Overnight Stay and Early Complications With Outpatient Arthroplasty.

BACKGROUND: The shift toward outpatient joint arthroplasty is rapidly growing, but concerns still remain on whether certain patients should be excluded from same-day discharge arthroplasty. The purpose of this study is to evaluate whether morbid obesity is a risk factor for perioperative complications after outpatient joint arthroplasty. METHODS: A retrospective review was performed from 2013 to 2017 of all outpatient primary total hip, total knee, partial knee, and revision hip and knee arthroplasties, yielding a cohort of 4863 patients (5988 arthroplasty procedures). Patients were separated and analyzed based on 2 groups: nonmorbidly obese (NMO) (BMI < 40 kg/m2) and morbidly obese (MO) (BMI ≥ 40 kg/m2). The NMO group consisted of 4870 arthroplasties and the MO group consisted of 1118 arthroplasties. Overnight stays, medical complications, and early perioperative complications were assessed between groups. RESULTS: Overnight stays occurred in 5.4% of NMO patients and 9.1% of MO patients (P < .001), with medical reasons for the overnight stay occurring in 3.2% of NMO and 6.4% of MO patients (P < .001). Respiratory/sleep apnea was the leading medical reason leading to overnight stay occurring in 4% of MO patients and 0.8% of NMO patients (P < .001). There was no significant difference between groups in direct facility transfers, emergency room visits/admissions, or medical complications within 90 days. Wound revisions, nonrevision surgery, or revisions within 90 days were significant between groups. CONCLUSION: MO patients did not have an increased risk of 90-day medical complications, readmission, or revisions after outpatient arthroplasty. However, MO patients did have a significantly higher incidence of overnight stay.

Does Patellar Resurfacing in Primary Total Knee Arthroplasty Increase the Risk of Manipulation?

INTRODUCTION: Patellar resurfacing in primary total knee arthroplasty (TKA) remains a controversial topic. The purpose of this study is to evaluate whether patellar resurfacing affects early complications and outcomes with a symmetric femoral component design. MATERIALS AND METHODS: Retrospective review was performed from 2015 to 2019 of all primary TKAs performed with the Klassic® Knee System (Total Joint Orthopedics, Inc., Salt Lake City, Utah) yielding a cohort of 526 patients (674 knees). Patients were compared based on whether the patella was resurfaced (391 knees, 58%) or unresurfaced (283 knees, 42%). Pre- and postoperative range of motion (ROM), University of California Los Angeles (UCLA) activity score, and Knee Society clinical (KSC), functional (KSF) and pain (KSP) scores were assessed between groups. Manipulation under anesthesia (MUA) and revisions were evaluated. The resurfaced group was significantly younger and had significantly more female patients, but they had no differences in preoperative body mass index (BMI), knee ROM, or Knee Society scores. One-year minimum follow up was available in 240 patients. RESULTS: Mean follow up was seven months (range, 1 to 35 months, SD ±7 months). MUAs were performed on 12 knees (4.2%) in the unresurfaced group and 37 knees (9.5%) in the resurfaced group (p=0.01). One patient (0.3%) in the unresurfaced group underwent a revision 1.5 years after the index surgery for a patellar resurfacing and polyethylene exchange. No other revisions were performed in either group. In patients with one-year minimum follow up, there was no significant difference in ROM or clinical or functional outcomes between groups. CONCLUSION: Patients who underwent a primary TKA with the TJO Klassic® Knee System with a resurfaced patella had a significantly higher incidence of manipulation under anesthesia than those with an unresurfaced patella. At most recent follow up, there was no significant difference in mean ROM or clinical outcome scores.

Accuracy of Patient-Reported Preoperative Opioid Use and Impact on Continued Opioid Use After Outpatient Arthroplasty.

BACKGROUND: The opioid epidemic has created a national healthcare crisis, and little is known about the accuracy of self-reported narcotic usage in arthroplasty. The purpose of this study is to evaluate the accuracy of self-reported opioid usage in patients undergoing outpatient arthroplasty. METHODS: A retrospective review was conducted on all primary unilateral arthroplasty procedures performed in 2018 at a free-standing ambulatory surgery center, yielding a cohort of 959 arthroplasties. Patient's prescription records were queried in the Ohio Automated Rx Reporting System for 3 months before surgery and minimum 9 months after surgery. These data were cross-referenced against the patient-reported preoperative use of narcotics. Three groups were evaluated: (G1) no preoperative narcotics, (G2) accurately self-reported on narcotics, and (G3) on narcotics but did not disclose. RESULTS: One hundred fourteen patients (12%) were on preoperative opioids based on the Ohio Automated Rx Reporting System query, with only 35 of these patients (31%) self-reporting. G2 had significantly lower postoperative knee range of motion, Knee Society Pain score, Knee Society Clinical score, Knee Society Functional score, Harris Hip Score, and University of California Los Angeles activity scores than G1. Overnight stays occurred in 1.2% of patients in G1, 3% of patients in G2 (P = .5), and 6.3% of patient in G3 (P = .002). All aspects of postoperative narcotic use were significantly higher in G2 and G3 compared to G1. The relative risk for narcotic refill after 90 days in G2 was 4.6 (95% confidence interval 3.7-5.8, P < .001). CONCLUSION: The majority of patients on preoperative narcotics did not disclose their use. Patients on narcotics preoperatively had significantly greater postoperative narcotic use including refills, total morphine milliequivalent, and risk of being on narcotics 90 days after surgery.

Validation of Gender and Height Predicting Femoral Size of the Oxford® Unicondylar Knee Arthroplasty: A Simplified Method.

BACKGROUND: Preoperative planning for implant sizes can help ensure proper implants are available as well as improve surgical efficiencies. The purpose of this study is to determine if patient gender and height can accurately predict the femoral size of the Oxford® knee. MATERIALS AND METHODS: 3986 knees (2085 female and 1901 males) that underwent a medial unicondylar knee arthroplasty (UKA) with the Oxford® mobile bearing knee (Zimmer Biomet, Warsaw, Indiana) were reviewed. Patient gender and height were compared to operative reports of the implanted femoral component. The relationship of height and femur size was then compared to create a prediction table for implant size. RESULTS: Females mean height was 64" (range, 48 to 78") and males mean height was 70" (range, 58 to 79"). In male patients, large implants were used in the majority of cases (76.6%). In female patients, small implants were used in the majority of cases (64.3%). Based on the relationship of height and femur size, two groups were created for each gender. In males: ≤66" = medium and ≥67" = large. In females: ≤64" = small and ≥65" = medium. Using these cutoffs, the correct implant would be chosen in 78.7% of cases (82.1% in males and 75.6% in females). Extra-small and extra-large sizes were used at the extremes of height in each gender, but never more commonly than small, medium, or large at any height. CONCLUSION: Patient gender and height can accurately predict femoral size of the Oxford® knee in the majority of cases. Our findings validate the original report of this method.

Medial Unicompartmental Knee Arthroplasty for the Treatment of Focal Femoral Osteonecrosis.

BACKGROUND: Previous research has indicated that unicompartmental arthroplasty may be an effective treatment for focal osteonecrosis in the knee; however, these reports have been composed of small patient cohorts and without characterization of the osteonecrotic lesions. Therefore, the purpose of this study was to investigate the effectiveness of unicompartmental arthroplasty for the treatment of focal osteonecrosis within the medial femoral condyle including an assessment of lesion size. METHODS: A consecutive series of >5,000 unicompartmental knee arthroplasties performed at a single institution was retrospectively reviewed to identify cases of medial femoral condyle osteonecrosis with a minimum 2-year follow-up. Lesion size was classified according to the ratio of lesion width to condylar width, as well as lesion depth relative to condylar depth. Patient-reported outcome measures and need for a revision procedure were studied. RESULTS: Sixty-four patients (32 males, 32 females; 65 knees) with a mean age of 64 years were included. The mean patient follow-up was 5.3 years (range, 2 to 12 years). The mean ratio of lesion width to condylar width was 64%, the mean lesion depth was 1.11 cm, and 82% of cases demonstrated subchondral collapse. At the time of the latest follow-up, patients demonstrated substantial improvements in the pain, function, and clinical components of the Knee Society Score, by 36, 25, and 51, respectively. Four patients (6%) required a revision, of which only 1 was for aseptic loosening of the femoral component. CONCLUSIONS: Unicompartmental arthroplasty is an effective treatment for advanced-stage focal osteonecrosis of the medial femoral condyle. Loss of component fixation to the femoral condyle did not appear to be a substantial concern because there was only 1 femoral failure as a result of aseptic loosening, despite lesions affecting a significant portion of the femoral condyle. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Ten-Year Minimum Outcomes and Survivorship With a High Flexion Knee System.

BACKGROUND: The purpose of this study is to report the long-term outcomes and survivorship of a high flexion knee system. METHODS: We identified 1312 patients (1664 knees) who underwent primary total knee arthroplasty with the Vanguard Complete Knee System with 10-year minimum follow-up. Preoperative and postoperative range of motion, Knee Society scores, complications, and reoperations were evaluated. RESULTS: At an average of 11.9 years of follow-up, 88 knees were revised (5.3%). The deep infection rate was 1.4%. There was an average range of motion improvement of 3.9°, pain level decreased by 35.8, Knee Society clinical scores improved by 48, and Knee Society functional scores improved by 15.1 (all P < .001). Survival was 96.4% at 10 years for aseptic causes and 95.5% for all causes. CONCLUSION: At a 10-year minimum follow-up, this high flexion knee system demonstrates excellent survivorship.

Outcomes After Arthroscopic Evaluation of Patients With Painful Medial Unicompartmental Knee Arthroplasty.

BACKGROUND: Persistent pain after medial unicompartmental knee arthroplasty (UKA) is a prevailing reason for revision to total knee arthroplasty (TKA). Many of these pathologies can be addressed arthroscopically. The purpose of this study is to examine the outcomes of patients who undergo an arthroscopy for any reason after medial UKA. METHODS: A query of our practice registry revealed 58 patients who had undergone medial UKA between October 2003 and June 2015 with subsequent arthroscopy. Mean interval from medial UKA to arthroscopy was 22 months (range 1-101 months). Indications for arthroscopy were acute anterior cruciate ligament tear (1), arthrofibrosis (7), synovitis (12), recurrent hemarthrosis (2), lateral compartment degeneration including isolated lateral meniscus tears (11), and loose cement fragments (25). RESULTS: Mean follow-up after arthroscopy was 49 months (range 1-143 months). Twelve patients have been revised from UKA to TKA. Relative risk of revision after arthroscopy for lateral compartment degeneration was 4.27 (6 of 11; 55%; P = .002) and for retrieval of loose cement fragments was 0.05 (0 of 25; 0%; P = .03). Relative risk for revision after arthroscopy for anterior cruciate ligament tear, arthrofibrosis, synovitis, or recurrent hemarthrosis did not meet clinical significance secondary to the low number of patients in these categories. CONCLUSION: The results of this study suggest that arthroscopic retrieval of cement fragments does not compromise UKA longevity. However, arthroscopy for lateral compartment degradation after UKA, while not the cause of revision, appears to be an ineffective treatment and predicts a high risk of revision to TKA regardless of its relative radiographic insignificance.

Early comparative outcomes of unicompartmental and total knee arthroplasty in severely obese patients.

BACKGROUND: Medial unicompartmental knee arthroplasty (UKA) may have advantages over total knee arthroplasty (TKA) in the setting of obesity. There has been no direct comparison between the two cohorts. This study compares outcomes and complications of severely obese patients undergoing medial UKA versus TKA. METHODS: Six hundred and fifty medial UKA and 1300 TKA were performed in patients with BMI >35kg/m2 (mean 41kg/m2) between 2007 and 2012. Pre- and postoperative ROM, Knee Society scores, perioperative factors, complications and reoperations were compared. RESULTS: UKA patients had higher preoperative ROM, and Knee Society pain (KSP), functional (KSF), and clinical (KSC) scores (p<0.001, p=0.0008, p=0.0003, p=0.051 respectively). Mean tourniquet times, operative times, and lengths of stay were lower after UKA. Four TKA patients required transfusion. Mean follow-up was 2.3years. The frequency of manipulation under anesthesia was higher in TKA patients (p<0.001), while the rate of component revision was similar between the two groups (1.2% vs. 1.7%, p=0.328). Frequency of deep infection was lower in the UKA group (p=0.016). Postoperative KSF, change in KSF, and ROM were higher (p<0.0001) after UKA, but KSP and KSC were equivalent. CONCLUSIONS: Severely obese patients who underwent medial UKA demonstrated equal survivorship with substantially fewer reoperations, reduced deep infection, and less perioperative complications at short term follow-up. Severely obese patients had improved KSF scores and maintenance of ROM after UKA compared with TKA.

Early Experience with Vitamin E Antioxidant-Infused Highly Cross-Linked Polyethylene Inserts in Primary Total Knee Arthroplasty.

BACKGROUND: In past decades, polyethylene wear was a major cause of failure in total knee arthroplasty (TKA). Polyethylene for use in arthroplasty has been vastly improved in recent years, with improved materials as well as manufacturing and sterilization processes. Testing has shown that infusion of vitamin E prevents oxidative degradation of polyethylene without remelting, allowing the material to maintain mechanical properties and wear resistance over time. The purpose of this study is to review the early result of patients undergoing primary TKA with vitamin E antioxidant-infused polyethylene inserts. MATERIALS AND METHODS: A query of our practice registry revealed 148 patients (163 knees) who underwent primary cemented TKA using the Vanguard® Complete Knee System and E1® Antioxidant Infused polyethylene bearings (Zimmer Biomet, Warsaw, Indiana) between May 2009 and May 2013. Indications for E1® bearings were younger, more active patients. There were 65 males (44%) and 82 females (56%). Mean age was 50.6 years and mean BMI was 37.3 kg/m2. RESULTS: At mean follow-up of 3.2 years (range 6 weeks to 6.4 years), there have been seven revisions (4.3%): three two-staged exchanges for infection, two for arthrofibrosis (one insert only, one femoral and tibial), and two (insert only) for late instability with imbalanced tight posteromedial and loose lateral structures. No aseptic loosening has occurred. Mean range of motion improved from 108° preoperatively to 112°, Knee Society clinical scores improved from 36 to 84 and function scores from 56 to 66. Postoperative radiographs, available for 160 TKA, revealed lateral patellar tilt in one knee, and satisfactory position, alignment, and fixation in all others. CONCLUSION: At up to 6.4 years' follow-up, two mechanical failures of the device have occurred and no aseptic loosening. Survival was 100% with aseptic loosening as the endpoint, and 95.7% with revision for any reason as the endpoint.