Commercial Synovial Antigen Testing is Inferior to Traditional Culture for the Diagnosis of Periprosthetic Joint Infection in Patients Undergoing Revision Total Knee Arthroplasty

BACKGROUND

Despite its limitations, a culture remains the "gold standard" for pathogen identification in patients who have periprosthetic joint infection (PJI). Recently, a synovial fluid antigen test has been introduced by a commercial entity. The purpose of this multicenter study was to determine the accuracy of the antigen test in the diagnosis of PJI.

METHODS

This retrospective study identified 613 patients undergoing revision total knee arthroplasty who had undergone preoperative synovial fluid analysis. A PJI was defined using the 2018 International Consensus Meeting (ICM) criteria. Patients who had an extended period (> 180 days) from aspiration to revision procedure (n = 62), those presenting within 90 days of their index arthroplasty procedure (n = 17), and patients who had an inconclusive ICM score (n = 8) were excluded. Using receiver operator characteristic curve analyses, we examined the utility of the microbial identification (MID) antigen test and any positive culture (either preoperative or intraoperative) in the diagnosis of PJI.

RESULTS

A total of 526 patients were included. Of these, 125 (23.8%) were ICM positive and 401 (76.2%) were ICM negative. Culture demonstrated an area under the curve (AUC) of 0.864, sensitivity of 75.2%, and specificity of 97.5%. On the other hand, the MID test exhibited an AUC of 0.802, sensitivity of 61.6%, and specificity of 98.8%. The AUC of culture was significantly higher than that of the MID test (P = .037). The MID test was positive in 41.9% of culture-negative PJI cases. We also observed a high rate of discordance (29.7%) when both culture and the MID test were positive in the ICM-positive group.

CONCLUSIONS

Synovial fluid antigen testing does not provide additional clinical benefit when compared to traditional cultures for the diagnosis of PJI. The antigen test had low sensitivity in the diagnosis of PJI and a relatively high rate of discordance with culture.

LEVEL OF EVIDENCE

Level III.

Prevalence of Depressive Symptoms in Aseptic Revision Total Knee Arthroplasty Based on the Mode of Failure

Background

Complications following total knee arthroplasty (TKA) that necessitate revision cause considerable psychological distress and symptoms of depression, which are linked to poorer postoperative outcomes, increased complications, and increased healthcare utilization. We aimed to identify the prevalence of mental health disorders and symptoms preoperatively and postoperatively in patients undergoing aseptic revision TKA and to stratify these patients based on their mechanism of failure.

Methods

All patients undergoing aseptic revision TKA from 2008 to 2019 with a minimum 1-year follow-up were retrospectively reviewed at a single institution. Patients (n = 394) were grouped based on 7 failure modes previously described. Patients were considered to have depressive symptoms if their Veterans RAND-12 mental component score was below 42. Preoperative and postoperative Veterans RAND-12 mental component scores at the latest follow-up were evaluated.

Results

Overall comparative prevalence of preoperative to postoperative depressive symptoms was 23.4%-18.8%. By mode of failure are as follows: arthrofibrosis (25.8%-16.7%), aseptic loosening (25.3%-18.9%), extensor mechanism disruption (25%-50%), failed unicompartmental knee arthroplasty (8.6%-14.3%), instability (25.7%-17.1%), osteolysis or polyethylene wear (23.1%-23.1%), and patellar failure (11.8%-23.5%). There was no difference in depressive symptoms among failure modes preoperatively (P = .376) or at the latest postoperative follow-up (P = .175).

Conclusions

The prevalence of depressive symptoms in revision TKA patients appears to be independent of failure mode. Surgeon awareness and screening for depressive symptoms in this patient population preoperatively with referral for potential treatment may improve early postoperative outcomes.

Comparison of Outcomes in High Versus Low Activity Level Patients After Total Joint Arthroplasty

BACKGROUND

Activity level (AL) recommendations following total joint arthroplasty (TJA) remain controversial. Our purpose was to compare implant survivorship of high activity (HA) and low activity (LA) patients after primary TJA. We hypothesized that there would be no difference in implant survivorship based on AL.

METHODS

This was a retrospective 1:1 matched cohort study after primary TJA with minimum 5-year follow-up. High activity patients were designated by the University of California and Los Angeles activity-level rating scale score ≥8 and matched to LA patients based on age (±5), sex, and body mass index (±5). There were 396 HA patients (149 knees and 48 hips) who met inclusion criteria. We analyzed revision rates, adverse events, and radiographic lucencies.

RESULTS

Crepitus was the most common adverse events in both HA and LA total knee arthroplasties (TKAs). Adverse events were rare in total hip arthroplasty (THA) cohorts. For both THA and TKA patients, the HA cohort did not have increased reoperations or revisions when compared to the LA cohort. No differences were noted in overall radiographic analysis between HA (16.1%) and LA (12.1%) TKA patients (P = .318), and in THA patients, more radiographic problems were noted in LA (P = .004).

CONCLUSION

We found no difference in minimum 5-year postoperative implant survivorship based on AL. This may change AL recommendations after TKA and THA.

Perioperative Sleep Quality Disturbances in Total Joint Arthroplasty is Multifactorial

BACKGROUND

Sleep quality following arthroplasty procedures is important for patient recovery and satisfaction, but remains poorly understood. The purpose of this study was to report risk factors for sleep disturbances in the perioperative period in patients undergoing primary total joint arthroplasty procedures.

METHODS

Sleep surveys were prospectively collected on 751 consecutive patients undergoing total joint arthroplasty at our institution between June 2019 and February 2021 at their preoperative and postoperative visits (2 and 6 weeks). Data were collected on patient demographics, opioid use (preoperatively and postoperatively) as well as tobacco and alcohol use, and specific medical diagnosis that may influence sleep patterns (ie, depression). Statistical analyses were performed using the Student's t-tests and 1-way analysis of variances.

RESULTS

For both total hip and total knee patients, worse sleep patterns preoperatively were found in patients who used opioids prior to surgery (P < .001), were current smokers (P < .001), and were aged less than 65 years (P < .001). Postoperative persistent opioid use (more than 3 months) was seen in patients who had worse reported sleep quality preoperatively (P < .001). In comparison to total hip arthroplasty, patients who underwent total knee arthroplasty were more likely to report less sleep in the postoperative period. Patients who were current smokers (compared to nonsmokers or previous smokers) (P = .014) had worse sleep quality at all time points that persisted at 6 weeks, although these differences were seen more in total hip patients than in total knee patients (P = .006 versus P = .059).

CONCLUSIONS

Sleep quality disturbances around the time of surgery appear to be multifactorial.

LEVEL OF EVIDENCE

Therapeutic Level III.

Patellofemoral Arthroplasty

Patellofemoral arthroplasty (PFA) as a treatment option for isolated patellofemoral disease continues to evolve. Enhancement in patient selection, surgical technique, implant design, and technology has led to improved short-term and midterm outcomes. Furthermore, in the setting of a younger patient with isolated patellofemoral arthritis, PFA represents an option for improved function with faster recovery times, bone preservation, maintenance of ligamentous proprioception, and the ability to delay total knee arthroplasty (TKA). The most common reason for revising PFA to a TKA is progression of tibiofemoral arthritis. In general, conversion of PFA to TKA leads to successful outcomes with minimal bone loss and the ability to use primary TKA implants and instrumentation. PFA seems to be a cost-effective alternative to TKA in appropriately selected patients with 5-, 10-PFA survivorships of 91.7% and 83.3%, respectively, and an annual revision rate of 2.18%; however, more long-term clinical studies are needed to determine how new designs and technologies affect patient outcomes and implant performance.

Joint aspiration for diagnosis of chronic periprosthetic joint infection: when, how, and what tests?

Diagnosing chronic periprosthetic joint infection (PJI) requires clinical suspicion in combination with both serological and synovial fluid tests, the results of which are generally applied to validated scoring systems or consensus definitions for PJI. As no single "gold standard" test exists, the diagnosis becomes challenging, especially in the setting of negative cultures or equivocal test results. This review aims to address the workup of chronic PJI and considerations for clinical evaluation to guide treatment. Following aspiration of the joint in question, a multitude of tests has been developed in an attempt to assist with diagnosis, including cell synovial white blood cell count, gram stain, cultures, leukocyte esterase, alpha-defensin, synovial C-reactive protein, multiplex polymerase chain reaction, next-generation sequencing, and interleukins. Each test has advantages and disadvantages and should be used in conjunction with the overall clinical picture to guide further clinical evaluation and treatment in this complex patient population.

Cannabis Use Does Not Affect Outcomes After Total Hip Arthroplasty

BACKGROUND

Cannabis use in patients undergoing arthroplasty has increased with ongoing legalization throughout the United States. The purpose of this study was to report total hip arthroplasty (THA) outcomes in patients self-reporting cannabis use.

METHODS

There were 74 patients who underwent primary THA from January 2014 to December 2019 at a single institution with minimum 1-year follow-up who had their self-reported cannabis use retrospectively reviewed. Patients who had a history of alcohol or illicit drug abuse were excluded. A match control was conducted based on age; body mass index; sex; Charlson Comorbidity Index; insurance status; and use of nicotine, narcotics, antidepressants, or benzodiazepines to patients undergoing THA who did not self-report cannabis use. Outcomes included Harris Hip Score (HHS), Hip Disability and Osteoarthritis Outcome Score for Joint Reconstruction (HOOS JR), in hospital morphine milligram equivalents (MMEs) consumed, outpatient MMEs prescribed, in hospital lengths of stay (LOS), postoperative complications, and readmissions.

RESULTS

There was no difference in the preoperative, postoperative, or change in Harris Hip Score or HOOS JR between cohorts. There was also no difference in hospital MMEs consumed (102.4 versus 101, P = .92), outpatient MMEs prescribed (119 versus 156, P = .11) or lengths of stay (1.4 versus 1.5 days, P = .32). Also, readmissions (4 versus 4, P = 1.0) and reoperations (2 versus 1, P = .56) were not different between groups.

CONCLUSION

Self-reported cannabis use does not influence 1-year outcomes after THA. Further studies are warranted to determine the efficacy and safety of perioperative cannabis use after THA to help guide orthopaedic surgeons in counseling patients.

Does Individualization of Cup Position Affect Prosthetic or Bone Impingement Following THA?

INTRODUCTION

Spinopelvic (SP) mobility patterns during postural changes affect three-dimensional acetabular component position, the incidence of prosthetic impingement, and total hip arthroplasty (THA) instability. Surgeons have commonly placed the acetabular component in a similar "safe zone" for most patients. Our purpose was to determine the incidence of bone and prosthetic impingement with various cup orientations and determine if a preoperative SP analysis with individualized cup orientation lessens impingement.

METHODS

A preoperative SP evaluation of 78 THA subjects was performed. Data was analyzed using a software program to determine the prevalence of prosthetic and bone impingement with a patient individualized cup orientation versus six commonly selected cup orientations. Impingement was correlated with known SP risk factors for dislocation.

RESULTS

Prosthetic impingement was least with the individualized choice of cup position (9%) vs. preselected cup positions (18 to 61%). The presence of bone impingement (33%) was similar in all groups and not affected by cup position. Factors associated with impingement in flexion were age, lumbar flexion, pelvic tilt (stand to flexed seated), and functional femoral stem anteversion. Risk factors in extension included standing pelvic tilt, standing SP tilt, lumbar flexion, pelvic rotation (supine to stand and stand to flexed seated), and functional femoral stem anteversion.

CONCLUSION

Prosthetic impingement is reduced with individualized cup positioning based on SP mobility patterns. Bone impingement occurred in one-third of patients and is a noteworthy consideration in preoperative THA planning. Known SP risk factors for THA instability correlated with the It dependspresence of prosthetic impingement in both flexion and extension.

Screening and Management of Malnutrition in Total Joint Arthroplasty

Malnutrition is an increasingly prevalent problem in patients undergoing total joint arthroplasty (TJA). Increased risks associated with TJA in the setting of malnourishment have been well documented. Standardized scoring systems in addition to laboratory parameters such as albumin, prealbumin, transferrin, and total lymphocyte count have been developed to identify and evaluate malnourished patients. Despite an abundance of recent literature, there is no consensus on the best approach for screening TJA patients from a nutritional standpoint. Although there are a variety of treatment options, including nutritional supplements, nonsurgical weight loss therapies, bariatric surgery, and the involvement of dieticians and nutritionists, the effect of these interventions on TJA outcomes has not been well characterized. This overview of the most current literature aims to provide a clinical framework for approaching nutrition status in arthroplasty patients. A comprehensive understanding of the tools available for managing malnourishment will facilitate improved arthroplasty care.

Alpha-Defensin Offers Limited Utility in Work-Up Prior to Reimplantation in Chronic Periprosthetic Joint Infection in Total Joint Arthroplasty Patients

BACKGROUND

Alpha-defensin (AD) is a synovial biomarker included in the 2018 consensus criteria for diagnosing periprosthetic joint infection (PJI). Its value in assessing eradication of infection prior to second stage reimplantation is unclear. The purpose of this study was to evaluate the impact of AD on eligibility for reimplantation following resection for chronic PJI.

METHODS

This study included patients who previously underwent resection arthroplasty for PJI. Synovial fluid aspirated from 87 patients was retrospectively reviewed. All patients completed a 6-week course of intravenous antibiotics and an appropriate drug holiday. Synovial white blood cell count, percentage neutrophils, and culture from the AD immunoassay laboratory were reviewed with serum erythrocyte sedimentation rate and C-reactive protein values from our institution. A modified version of the 2018 consensus criteria was used, including white blood cell count, percentage neutrophils, erythrocyte sedimentation rate, and C-reactive protein. AD was then added to determine if it changed diagnosis or clinical management.

RESULTS

Four patients were categorized as "infected" (score >6), none exhibited a positive AD or positive culture. Sixty eight patients were diagnosed as "possibly infected" (score 2 to 5), none had a positive AD, and one had a positive culture (Cutibacterium acnes). AD did not change the diagnosis from "possibly infected" to "infected" in any case or alter treatment plans. Fifteen patients had a score of <2 (not infected) and none had a positive AD.

CONCLUSION

The routine use of AD in the work-up prior to a second-stage arthroplasty procedure for PJI may not be warranted.

Effectiveness of Manual Terminal Cleaning Varies on High-Touch Surfaces Near the Operative Field

Background

Periprosthetic joint infection may result from pathogen to patient transmission within the environment. The purpose of this study is to evaluate the contamination level of selected high-touch surfaces in the operating room (OR) using a blacklight fluorescent marking system after a manual terminal clean.

Methods

Prior to the manual terminal clean, 16 high-touch surfaces were marked using a blacklight fluorescent gel. The marked areas were assessed the next morning for thoroughness of cleaning. Surfaces were categorized based on the average percent of the marks removed as “clean” (>75%), “partially clean” (26%-74%), or poorly cleaned (<25%). This process was repeated randomly 12 times. Terminal cleaning was done in the standard fashion, and the perioperative team was unaware of the initiation of this study.

Results

A total of 936 marks were analyzed. There was a significant difference in the number of marks completely clean (29.1%, 272/936) vs marks that were not touched (40.8%, 382/936), P < .001. Only the OR back table (75%) had a rating of clean. Partially clean areas included Mayfield table (72%), overhead lights (70.1%), infusion pump (61.1%), clock reset button (58.3%), table remote control (50%), tourniquet machine (50%), and the OR table (33.3%). Poorly cleaned surfaces included anesthesia medication cart (21.8%), door handles (20.8%), phone (16.7%), electrocautery unit (16.7%), foot pedal (16.7%), anesthesia cart (16.2%), nurses’ station (14.1%), and supply cabinet doors (6%).

Conclusions

Effectiveness of manual terminal cleaning varied greatly across surfaces. In general, surfaces further from the operative field were less likely to have markings removed.

Self-Reported Cannabis Use Is Associated With a Lower Rate of Persistent Opioid Use After Total Joint Arthroplasty

Background

Legalization of cannabis, along with concern over prescription opiate use, has garnered interest in cannabis for adjuvant pain control. This study examines the relationship between cannabis and opioid consumption after total hip (THA) or knee (TKA) arthroplasty.

Methods

Patients undergoing primary THA or TKA with minimum 6-month follow-up who self-reported cannabis use were retrospectively reviewed. A total of 210 patients (128 TKAs and 82 THAs) were matched by age; gender; type of arthroplasty; Charlson Comorbidity Index; and use of nicotine, antidepressants, or benzodiazepines to patients who did not self-report cannabis use. Patients receiving an opioid prescription after 90 days postoperatively were classified as persistent opioid users (POUs). Duration of opioid use (DOU) was calculated for non-POU patients as the time between surgery and their last opioid prescription. Differences in inpatient morphine milligram equivalents (MMEs), outpatient MMEs, POU, and DOU were analyzed.

Results

Cannabis users required equivalent inpatient and outpatient MMEs. There was no difference in DOU. There was a significant difference in POU between cannabis users and matched controls (1.4% [n = 3] vs 9.5% [n = 20], P < .001, respectively). Grouping patients by TKA or THA, there remained a difference in POU for TKA (1.5% [n = 2] vs 10.9% [n = 14], P = .002) and THA (1.2% [n = 1] vs 7.3% [n = 6], P = .04). There was no difference in inpatient or outpatient MMEs or DOU for THA and TKA patients.

Conclusions

There is a reduced rate of POU in patients who self-report perioperative cannabis use. Prospective studies are needed to clarify the role of cannabis as an adjunct to perioperative pain control.

Use of Cannabis Does Not Decrease Opioid Consumption in Patients Who Underwent Total Joint Arthroplasty

Background

The primary purpose of this study was to determine if cannabis use decreases narcotic consumption in patients undergoing total joint arthroplasty (TJA).

Material and methods

Forty-six patients undergoing a primary unilateral TJA, who self-reported the use of cannabis, were prospectively enrolled and completed this study between July 2015 and November 2019. This cohort was prospectively matched to patients who did not report cannabis use. Morphine equivalents (MEs) were averaged and recorded at 1 and 2 weeks postoperatively. Secondary outcomes and complications were recorded and reported.

Results

There were no differences noted in ME during the hospitalization between the user (78.7 ± 58.5) and nonusers (70.4 ± 46.3), P = .455. ME daily average did not differ between the cohorts (user [36.8 ± 30.7] and nonuser [31.7 ± 25.6] at 1 week (P = .389) or user [22.5 ± 26.3] and nonusers [15.9 ± 18.3] at 2 weeks, P = .164, postoperatively). The total ME at 2 weeks did not differ between the user and nonuser groups (415 ± 375 vs 333 ± 275, P = .235). Pain scores at 1 week were significantly higher in patients who used cannabis (4.1 ± 1.9 vs 3.4 ± 1.6, P = .05). No differences in pain were noted during the patient's hospitalization or at 2- (P = .071) or 6-week (P = .111) follow-up. No differences in secondary outcomes or complications were noted.

Conclusion

We were unable to show a decrease in narcotic consumption in patients who use cannabis undergoing primary unilateral joint replacement. These findings do not support the routine use of cannabis to decrease or supplement narcotic use after primary TJA.

Level of evidence

Level II therapeutic.

A back table ultraviolet light decreases environmental contamination during operative cases

BACKGROUND

The purpose of this study is to assess the impact of a germicidal ultraviolet light-emitting diode (LED) on the contamination level of a back table in the operating room (OR) during total joint arthroplasty procedures.

METHODS

Eight Tryptic Soy Agar petri plates were placed on a table located near the operative field and exposed to air. One plate was removed on the hour over an 8-hour time span. The back table had either an UV-LED for disinfection or a sham UV-LED. This process was repeated in 12 different ORs (6 with UV light, 6 with sham device). The plates were then incubated for 48 hours at 36°C ± 1°C . Colony forming units (CFU) were recorded 24 and 48 hours after incubation.

RESULTS

There was a statistically significant difference in total CFUs between the intervention vs sham at 24-hours (27 vs 95, P = .0001) and 48-hours (38 vs 122, P < .0001). The multivariate analysis revealed that the 24-hour and 48-hour count, the predictors UV light (P = .002) and hour of plate removal (P = .050) were statistically significantly associated with CFU counts. Together, the predictor variables explained 15.8% and 23.0% of the variance in CFU counts at 24- and 48-hours, respectively.

CONCLUSIONS

A back table UV-LED may decrease environmental contamination near the operative field. This has potential to lead to a decrease in joint infection.

Evaluation of Low-Dose Versus High-Dose Opioid Pathway in Opioid-Naïve Patients After Total Knee Arthroplasty

Background

Pain control after total knee arthroplasty (TKA) remains challenging. Tramadol is a weak opioid with potentially lower side effects and risk for dependency than stronger opioids. The purpose of this study was to evaluate efficacy and safety of tramadol after TKA in opioid-naïve patients compared with stronger opioids.

Methods

A retrospective review of patients who underwent primary TKA was performed. In September 2018, opioid-naïve patients were prescribed tramadol instead of oxycodone. Patients receiving tramadol (low-opioid group) were matched to patients discharged with oxycodone before this transition (high-opioid group). We compared morphine milligram equivalent (MME) consumption and outcomes up to 3 months postoperatively.

Results

Two-hundred and five patients underwent TKA, with 126 receiving tramadol. Fourteen patients were converted to stronger opioid (11.2% conversion rate). Seventy patients from the low-opioid group were matched to 70 patients in the high-opioid group. Average daily inpatient MME consumption was higher in the high-opioid group (40.0 ± 27.4 vs 16.3 ± 10.9, P = .000). Outpatient prescribed MME was significantly higher in the high-opioid group (135.5 ± 71.5 vs 75.3 ± 51.3, P = .000) along with a higher number of refills (0.53 ± 1.1 vs 0.886 ± 0.94, P = .041). Knee range of motion was not statistically different at any timepoint postoperatively. There was higher adverse event rate in the low-opioid group (8.6% vs 5.7%) but not statically significant.

Conclusions

Low opioid regimen following TKA showed lower MME consumption than high opioid regimen with no effect on outcomes up to 3 months. Use of low opioid regimen should be considered for TKA surgery.

Total Knee Arthroplasty Assessments Should Include Strength and Performance-Based Functional Tests to Complement Range-of-Motion and Patient-Reported Outcome Measures

Range of motion (ROM) and pain often define successful recovery after total knee arthroplasty (TKA), but these routine clinical outcomes correlate poorly or not at all to functional capacity after TKA. The purpose of this Perspective is to underscore the importance of muscle strength and performance-based functional tests in addition to knee ROM and patient-reported outcome (PRO) measures to evaluate outcomes after TKA. Specifically: (1) muscle strength is the rate-limiting step for recovery of function after TKA; (2) progressive rehabilitation targeting early quadriceps muscle strengthening improves outcomes and does not compromise ROM after TKA; (3) ROM and PROs fail to fully capture functional limitations after TKA; and (4) performance-based functional tests are critical to evaluate function objectively after TKA. This Perspective also addresses studies that question the need for or benefit of physical therapy after TKA because their conclusions focus only on ROM and PRO measures. Future research is needed to determine the optimal timing, delivery, intensity, and content of physical therapy.

Increased Prevalence of Depressive Symptoms in Patients Undergoing Revision for Periprosthetic Joint Infection

Background

Periprosthetic joint infection (PJI) is a devastating complication after total joint arthroplasty. Patients undergoing revision for PJI may experience psychological distress and symptoms of depression, both of which are linked to poor postoperative outcomes. We, therefore, aim to identify the prevalence of depression and depressive symptoms in patients before treatment for PJI and their link to functional outcomes.

Methods

Patients undergoing either debridement with implant retention (DAIR) or 2-stage exchange for PJI with minimum 1-year follow-up were retrospectively reviewed. The 2-stage (n = 37) and single-stage (n = 39) patients that met inclusion criteria were matched based off age (±5 years), gender, and body mass index (±5) to patients undergoing aseptic revisions. Outcomes evaluated included a preoperative diagnosis of clinical depression and preoperative and postoperative Veterans RAND 12 Item Health Survey mental component score and physical component score.

Results

Compared to matched controls, the prevalence of depressive symptoms was significantly greater in patients undergoing 2-stage exchange preoperatively (40.5% vs 10.8%, P < .01) but not postoperatively (21.6% vs 10.8%, P = .20). Patients undergoing DAIR with either preoperative depressive symptoms (31.3 vs 40.9, P = .05) or a preoperative diagnosis of depression (27.7 vs 43.1, P < .01) had significantly lower physical component scores postoperatively.

Conclusions

Patients undergoing 2-stage exchange for PJI have a four times higher prevalence of preoperative depressive symptoms than patients undergoing aseptic revision. Patients undergoing DAIR with depression or preoperative depressive symptoms have lower functional scores postoperatively. Orthopedic surgeon screening of PJI patients with referral for treatment of depression may help improve outcomes postoperatively.

Bone Cement Hypersensitivity in Patients With a Painful Total Knee Arthroplasty: A Case Series of Revision Using Custom Cementless Implants

Little is known about patients with bone cement hypersenstivity after total knee arthroplasty (TKA). We present 7 patients implanted with 8 TKAs with clinical failure and a cement hypersensitivity diagnosis. All demonstrated hypersensitivity to bone cement via skin patch and/or lymphocyte transformation testing. All 7 patients also showed hypersensitivity to metal, most commonly nickel. Patients underwent custom cementless TKA revision. Prerevision and postrevision outcome measures, radiographs, intraoperative findings, and postrevision complications are reported. Functional scores improved after revision except Veterans RAND-12 mental component scores, which declined. Four patients continue to exhibit symptoms postoperatively, while one patient has had 3 additional surgical procedures. Patients presenting with bone cement hypersensitivity after TKA are particularly challenging. Evidence-based guidelines are lacking, and revision surgery may not relieve the presenting symptoms.

Ten-Year Follow-Up of High-Flexion Versus Conventional Total Knee Arthroplasty: A Matched-Control Study

BACKGROUND

High-flexion total knee arthroplasty (HF-TKA) prostheses were designed with hopes of improving knee function. Studies have suggested increased failure with HF-TKAs. The purpose is to compare clinical results of HF-TKA versus conventional TKA (C-TKA) from the same implant system with long-term follow-up.

METHODS

This review of prostheses implanted between 2004 and 2007 matched 145 of 179 possible HF-TKAs with 145 of 1347 possible C-TKAs. Mean follow-up was 121.5 ± 20.3 months. We were unable to match 12 HF-TKAs. HF-TKAs with less than 8-year follow-up were excluded. The primary outcome was failure requiring revision. Secondary outcomes included range of motion (ROM), Knee Society Scores (KSS), and radiolucent lines.

RESULTS

In the matched cohort, there were 15 HF-TKA reoperations, 8 of which involved component revisions. There were 12 reoperations in the C-TKA cohort but no component revisions (P = .001). The analysis of the unmatched cohorts revealed a higher revision rate for HF-TKAs (P = .039) (HF-TKA: 10/179 vs C-TKA: 27/1347). At final follow-up, HF-TKAs exhibited more prosthesis radiolucent lines without evidence of loosening. Particularly, HF-TKAs demonstrated more femoral zone IV radiolucencies (38.7%) at final follow-up compared with C-TKAs (13.8%) (P < .001). There were no differences found between cohorts in ROM or KSS.

CONCLUSION

This study found an increased incidence of failure requiring revision with the HF-TKA in the matched and unmatched analyses. Higher incidences of radiolucent lines were found with HF-TKA. With no observed differences in ROM or KSS and a higher rate of failure with HF-TKA, there appears to be no advantage for use of the HF-TKA.

Spinopelvic mobility affects accuracy of acetabular anteversion measurements on cross-table lateral radiographs

AIMS

Cross-table lateral (CTL) radiographs are commonly used to measure acetabular component anteversion after total hip arthroplasty (THA). The CTL measurements may differ by > 10° from CT scan measurements but the reasons for this discrepancy are poorly understood. Anteversion measurements from CTL radiographs and CT scans are compared to identify spinopelvic parameters predictive of inaccuracy.

METHODS

THA patients (n = 47; 27 males, 20 females; mean age 62.9 years (SD 6.95)) with preoperative spinopelvic mobility, radiological analysis, and postoperative CT scans were retrospectively reviewed. Acetabular component anteversion was measured on postoperative CTL radiographs and CT scans using 3D reconstructions of the pelvis. Two cohorts were identified based on a CTL-CT error of ≥ 10° (n = 11) or < 10° (n = 36). Spinopelvic mobility parameters were compared using independent-samples t-tests. Correlation between error and mobility parameters were assessed with Pearson's coefficient.

RESULTS

Patients with CTL error > 10° (10° to 14°) had stiffer lumbar spines with less mean lumbar flexion (38.9°(SD 11.6°) vs 47.4° (SD 13.1°); p = 0.030), different sagittal balance measured by pelvic incidence-lumbar lordosis mismatch (5.9° (SD 18.8°) vs -1.7° (SD 9.8°); p = 0.042), more pelvic extension when seated (pelvic tilt -9.7° (SD 14.1°) vs -2.2° (SD 13.2°); p = 0.050), and greater change in pelvic tilt between supine and seated positions (12.6° (SD 12.1°) vs 4.7° (SD 12.5°); p = 0.036). The CTL measurement error showed a positive correlation with increased CTL anteversion (r = 0.5; p = 0.001), standing lordosis (r = 0.23; p = 0.050), seated lordosis (r = 0.4; p = 0.009), and pelvic tilt change between supine and step-up positions (r = 0.34; p = 0.010).

CONCLUSION

Differences in spinopelvic mobility may explain the variability of acetabular anteversion measurements made on CTL radiographs. Patients with stiff spines and increased compensatory pelvic movement have less accurate measurements on CTL radiographs. Flexion of the contralateral hip is required to obtain clear CTL radiographs. In patients with lumbar stiffness, this movement may extend the pelvis and increase anteversion of the acetabulum on CTL views. Reliable analysis of acetabular component anteversion in this patient population may require advanced imaging with a CT scan. Cite this article: Bone Joint J 2021;103-B(7 Supple B):59-65.

Tourniquet Use Improves Cement Penetration and Reduces Radiolucent Line Progression at 5 Years After Total Knee Arthroplasty

BACKGROUND

Although the effect of tourniquet use during total knee arthroplasty (TKA) on functional outcomes is controversial, there are little data examining cement penetration and implant stability. This study examines the effect of tourniquet use on cement penetration and radiolucent line (RLL) progression.

METHODS

Patients undergoing primary total knee arthroplasty with a single surgeon, implant, and cement with minimum 5-year follow-up were retrospectively reviewed. Tourniquet use was defined as 30 minutes minimum, while no tourniquet was 0 minutes. Patients were 1:1 matched (n = 61 per group) by age (±5), gender, body mass index (±5), and follow-up (±2 years). Cement penetration and RLL were measured on the tibia at 6 weeks, and RLL at 1, 2, and 5 years postoperatively using the Knee Society Radiographic Evaluation System.

RESULTS

Cement penetration was significantly increased in the tourniquet group in anterior-posterior zones 1 (2.16 vs 1.03 mm, P < .0005), 2 (2.23 vs 1.51 mm, P < .0005), and 5 (8.56 vs 6.3 mm, P = .009), and lateral zones 1 (2.89 vs 2.17 mm, P < .0005), 2 (2.86 vs 2.12 mm, P < .0005), 3P (3.99 vs 3.5 mm, P = .039), and 5 (8.18 vs 5.93 mm, P = .006). Cumulative cement penetration averaged 34.48 vs 43.33 mm in the tourniquet group (P < .005). Progression of RLL >2 mm was observed in 27.8% (17/61) vs 11.4% (7/61) of patients in the tourniquet group (P < .005). There were 2 failures for aseptic tibial loosening in the no tourniquet group.

CONCLUSION

Tourniquet use improves cement penetration and reduces RLL progression. Dryer surfaces during cementation may improve penetration, resulting in superior initial fixation strength and potentially reducing the long-term risk of aseptic loosening.

A Prophylactic Tibial Stem Reduces Rates of Early Aseptic Loosening in Patients with Severe Preoperative Varus Deformity in Primary Total Knee Arthroplasty

BACKGROUND

Patients with a preoperative varus deformity >8 degrees are at increased risk of aseptic loosening after total knee arthroplasty. This study analyzes the effect of a tibial stem on the rate of aseptic loosening in patients with a severe preoperative varus deformity.

METHODS

Patients with a preoperative varus deformity of >8 degrees and 2-year minimum follow-up with a stemmed tibial component (n = 67) were matched 1:2 to patients with a similar preoperative varus deformity with a standard tibial component (n = 134). Radiolucent lines were measured on the tibia at 6 weeks, 1 year, and 2 years postoperatively using the Knee Society Radiographic Evaluation System. Failure was defined as revision due to aseptic loosening of the tibial component. Outcomes were evaluated using Student's t-tests and log-rank tests.

RESULTS

Patients with tibial stems had greater preoperative deformity (12.9 vs 11.3 degrees, P = .004). There was no difference in postoperative alignment (1.7 vs 2.1 degrees varus, P = .25) or tibial component angle (1.8 vs 2.1 degrees varus, P = .33). Patients with stems were more likely to have more constraint (44.8% vs 1.5%, P < .001). Progression of radiolucent lines >2 mm was observed in 17.6% (23/134) vs 5.97% (4/67) of patients in the stem group (P = .03). Rates of aseptic loosening were lower in the stem group (0% vs 5.15%, P = .05).

CONCLUSION

Despite worse preoperative deformity and higher utilization of constraint, tibial stem use in patients with severe preoperative varus deformity resulted in lower rates of aseptic loosening. Prophylactic use of stems in these patients may help increase implant survival.

Incidence and Predictive Risk Factors of Postoperative Urinary Retention After Primary Total Knee Arthroplasty

BACKGROUND

Postoperative urinary retention (POUR) after total knee arthroplasty (TKA) may cause urologic injury and delay patient discharge. This study measures the incidence of POUR and identifies predictive risk factors.

METHODS

Two-hundred seventy-one consecutive patients undergoing primary unilateral TKA were prospectively enrolled. Bladder scans were performed in the postanesthesia care unit (PACU) and every four hours thereafter. POUR was defined as >400cc with inability to void and was treated with catheterization. Patient demographics, urologic history, operative data, perioperative medications, and bladder scanner volumes were investigated with the univariate and multivariate logistic regression analysis.

RESULTS

Fifty-five patients (20%) developed POUR. Compared with non-POUR patients, PACU bladder scan volumes were greater in patients who developed POUR (344cc vs 120cc, P < .001). POUR patients had lower BMI (27.8 vs 29.4, P = .03), longer operative duration (83.9 vs 76.0 minutes, P = .002), and lower ASA scores (2.2 vs 2.4, P = .02). Total intravenous fluid was equivalent between groups (1134cc vs 1185cc, P = .41). POUR patients received less narcotics measured by morphine milligram equivalents (16.1 vs 23.9, P < .001). Fifteen variables including spinal type (bupivacaine and ropivacaine) and paralytic use were not predictive of POUR. Potentially predictive variables included anesthetic types administered (spinal, general, regional, and combination) and perioperative administration of nonsteroidal anti-inflammatory drugs (NSAIDs), glycopyrrolate, and muscle relaxants. The multivariate analysis showed that NSAIDs (P = .05) and glycopyrrolate (P = .04) were significant predictors.

CONCLUSION

A significant percentage of patients develop POUR after TKA. Select patient demographics and PACU bladder scanning may identify those at risk. Appropriate pain control and judicious use of perioperative NSAIDs and glycopyrrolate may help minimize the risk of POUR.

Alpha-Defensin Is Not Superior to Traditional Diagnostic Methods for Detection of Periprosthetic Joint Infection in Total Hip Arthroplasty and Total Knee Arthroplasty Patients

BACKGROUND

Synovial fluid alpha-defensin (AD) may improve diagnostic accuracy of periprosthetic joint infection (PJI) following total knee (TKA) and hip (THA) arthroplasty but is only available as send-out test. This study evaluated laboratory result accuracy between send-out test vs hospital labs and if AD made a difference in treatment plan.

METHODS

A retrospective review was performed of 152 consecutive patients with a TKA or THA joint aspiration for painful or clinically concerning joint. Synovial fluid was sent to our institution (hospital-based labs, HBL) and send-out immunoassay laboratory (Synovasure). Patients were scored with specific criteria from validated scoring system for PJI using HBL and Synovasure results. The score with and without AD test was compared to determine if AD impacted patient management.

RESULTS

Overall, there was strong agreement between institutions for PJI diagnosis (Cohen's kappa score 0.96). Twenty-nine patients had PJI diagnosis (score ≥6), of which 28 (97%) had positive AD with 1 false-negative result. Sixty-three patients had inconclusive score (between 2 and 5) and 60 patients had negative PJI diagnosis (score ≤1). Of these patients, 5 underwent surgery for infection. Two patients had surgery for positive AD, 2 for positive culture, and 1 because of elevated HBL results. The AD test changed the PJI diagnosis and influenced decision for surgery in only 1.3% (2/152) of patients.

CONCLUSION

Minimal differences were found in laboratory values between institutions. The addition of AD may be useful in cases of equivocal laboratory results but does not appear to be necessary for routine diagnosis of PJI after TKA/THA.

LEVEL EVIDENCE

Level III.

Alpha-Defensin Offers Limited Utility in Routine Workup of Periprosthetic Joint Infection

BACKGROUND

Alpha-defensin (AD) is a synovial biomarker included as a minor criterion in the scoring system for diagnosing periprosthetic joint infection (PJI). The purpose of this study is to study the impact of AD on diagnosis and management of PJI.

METHODS

Synovial fluid from 522 patients after total knee and hip arthroplasty was retrospective reviewed. Synovial white blood cell count, percentage of neutrophils, and culture from the AD immunoassay laboratory were reviewed with serum erythrocyte sedimentation rate and C-reactive protein values from our institution. A modified version of the 2018 scoring system for diagnosis of PJI was used, only scoring white blood cell count, percentage of neutrophils, erythrocyte sedimentation rate, and C-reactive protein. AD was then analyzed with these scores to determine if AD changed diagnostic findings or clinical management.

RESULTS

Eight-two patients were categorized as "infected" (score ≥6), of which 76 patients had positive AD. Of the 6 "infected" patients with negative AD, 2 had positive cultures (Staphylococcus epidermidis). Two-hundred thirteen patients were diagnosed as "possibly infected" (score 2-5). Fourteen of these patients had positive AD, of which 5 had positive cultures assisting with the diagnosis. The AD test changed the diagnosis from "possibly infected" to "infected" in 8 patients (1.5%) but only altered treatment plan in 6 patients (1.1%). A score <2 (not infected) was calculated in 227 patients with no patients having positive AD.

CONCLUSION

AD may be beneficial in some cases where laboratory values are otherwise equivocal; however, its routine use for the diagnosis of PJI may not be warranted.

Metal Artifact Reduction Sequence Magnetic Resonance Imaging Abnormalities in Asymptomatic Patients With a Ceramic-on-Ceramic Total Hip Replacement

BACKGROUND

Metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) has recently gained increased utilization as a screening modality in patients with a total hip arthroplasty (THA). Fluid collections have been documented in asymptomatic patients with various bearing surfaces. The purpose of this study is to determine the frequency and types of MARS MRI-documented abnormalities in asymptomatic patients with a ceramic-on-ceramic (CoC) THA.

METHODS

Thirty-seven patients (42 hips) with a minimum 2-year follow-up after THA with CoC THA implants were enrolled in this study. The inclusion criteria were the absence of hip pain and the availability of appropriate follow-up radiographs. All patients underwent a MARS MRI. Abnormalities were documented using a previously described method.

RESULTS

Fluid collections were observed in 8 (19%) asymptomatic hips in this cohort. Four of the 8 hips demonstrated intracapsular synovitis, and 3 of these hips had a thickened synovium. Extra-articular fluid collections with direct intra-articular communication were identified in 4 hips, with 2 of these hips demonstrating synovial thickening. No signs of osteolysis were noted on radiographs or the MARS MRI scans.

CONCLUSION

Asymptomatic fluid collections occur in patients after CoC THA similar to other bearing surfaces. We continue to follow these patients in an effort to determine the clinical significance and natural history of these findings.

LEVEL OF EVIDENCE

Diagnostic Level IV.

Usefulness of Perioperative Laboratory Tests in Total Hip and Knee Arthroplasty: Are They Necessary for All Patients?

Background

Laboratory studies are routinely obtained preoperatively and postoperatively for total hip arthroplasty (THA) and total knee arthroplasty (TKA). This study evaluates the necessity of routine, perioperative laboratory tests and identifies risk factors for laboratory-associated interventions.

Methods

This retrospective review evaluated 967 consecutive patients scheduled for primary, unilateral TKAs (n = 593) or THAs (n = 374) over an 18-month period at a single institution. Preoperative prothrombin time (PT) and International Normalized Ratio (INR), complete blood count (CBC), complete metabolic panel (CMP), and postoperative CBC and basic metabolic panel (BMP) were recorded along with any laboratory-associated intervention. Patient demographics and comorbidities identified risk factors for abnormal or actionable laboratory studies.

Results

Preoperatively, the actionable rates for PT/INR, CMP, and CBC were 0.3%, 1.4%, and 0.5%, respectively. Vascular, renal, and immunologic diseases were risk factors for an actionable CBC. Risk factors for an actionable CMP include cardiac arrhythmia and diabetes. There were no risk factors for an actionable PT/INR. Postoperatively, only 1.5% of BMPs and 1.5% of CBCs were actionable. Congestive heart failure, renal disease vascular disease, or history of cancer (P = .030) were risk factors for an actionable CBC. There were no risk factors for an actionable BMP. Patients with an abnormal preoperative lab were 2.4 times more likely to have an actionable postoperative lab. Patients with an actionable preoperative lab were 11.3 times more likely to have an actionable postoperative lab.

Conclusion

Routine preoperative and postoperative labs may not be necessary on all patients undergoing a TKA or THA. Comorbid risk factors and abnormal or actionable preoperative CMPs and CBCs can help determine the usefulness of postoperative laboratory assessments.

The Effect of the COVID-19 Pandemic on Hip and Knee Arthroplasty Patients in the United States: A Multicenter Update to the Previous Survey

Background

In March 2020, elective total hip and knee arthroplasty (THA and TKA) were suspended across the United States in response to the COVID-19 pandemic. We had previously published the results of a survey to the affected patients from 6 institutions. We now present the results of a larger distribution of this survey, through May and June 2020, to electively scheduled patients representing different regions of the United States.

Methods

Fifteen centers identified through the American Association of Hip and Knee Surgeons Research Committee participated in a survey study of THA and TKA patients. Patients scheduled for primary elective THA or TKA but canceled due to the COVID-19 elective surgery stoppage (3/2020-5/2020) were included in the study. Descriptive statistics along with subgroup analysis with Wilcoxon rank were performed.

Results

In total, surveys were distributed to 2135 patients and completed by 848 patients (40%) from 15 institutions. Most patients (728/848, 86%) had their surgery postponed or canceled by the surgeon or hospital. Unknown length of surgical delay remained the highest source of anxiety among survey participants. Male patients were more likely to be willing to proceed with surgery in spite of COVID-19. There were minimal regional differences in responses. Only 61 patients (7%) stated they will continue to delay surgery for fear of contracting COVID-19 while in the hospital.

Conclusion

Similar to the previous study, the most anxiety-provoking thought was the uncertainty, over if and when the canceled joint replacement surgery could be rescheduled. Patients suffering from the daily pain of hip and knee arthritis who have been scheduled for elective arthroplasty remain eager to have their operation as soon as elective surgery is allowed to resume.

Patient Perception Regarding Potential Effectiveness of Cannabis for Pain Management

BACKGROUND

Self-reported cannabis use has increased since its recent legalization in many states. The primary objective of this study is to describe patients' beliefs regarding the potential effectiveness of cannabis and gauge patient acceptance of these compounds if prescribed by a physician.

METHODS

Five hundred fifty-five consecutive new patients in a total joint arthroplasty (TJA) practice completed a questionnaire at their new patient or preoperative encounter. Questions regarding their beliefs about the potential effectiveness of cannabis for pain management were presented to the patient. Each question was scored in accordance to the agreement of the patient. Data were also collected on patient demographics, and current cannabis, tobacco, and/or alcohol use.

RESULTS

Current cannabis use was reported in 20.2% (112/555) of respondents. Patients were interested in using cannabis if prescribed by a physician for acute (75.3%, 418/515) and chronic (74.4%, 415/555) pain. Seventy-seven percent (428/555) of patients believe (strongly agree or agree) that cannabis should be legalized for medical use, whereas only 39% (217/555) strongly agree or agree that cannabis should be legalized for recreational use. Patients strongly agree or agree that cannabis can help with sleep or anxiety, 44.9% (249/555) and 49.4% (274/555) respectively. Most patients had never smoked (53%, 294/555) and drink one or less alcoholic beverage per week (52.1%, 299/555).

CONCLUSION

Patients believe that cannabis may be helpful for pain management after TJA and are willing to use if prescribed by their orthopedic provider. Further research is warranted to determine if cannabis is a helpful adjunct to pain management in this patient population.

Reliability of Spinopelvic Measurements That May Influence the Cup Position in Total Hip Arthroplasty

BACKGROUND

Spinopelvic pathology has been identified as a potential risk factor for instability after total hip arthroplasty. Spinopelvic radiographic parameters used to diagnose spinopelvic disease may also impact optimal cup placement. The purpose of this study was to assess the arthroplasty surgeon accuracy in making spinopelvic measurements.

METHODS

Five fellowship-trained or in-training arthroplasty surgeons reviewed 44 lateral lumbar radiographs in two sessions. All evaluators were instructed how to perform measurements but had little experience in doing so. Traditional measurements included the pelvic tilt (PT), pelvic incidence (PI), and sacral slope (SS), and novel measurements included the acetabular ante-inclination (AI) and pelvic femoral angle. Surgeon measurements were compared with those made by experienced engineers. intraclass coefficients (ICCs) were calculated and interpreted.

RESULTS

The interobserver reliability for 4 of 5 of the spinopelvic parameters was good to excellent (ICC >0.75) with the highest reliability seen for PI measurement (ICC = 0.939). Only moderate interobserver reliability was observed for AI measurement (ICC = 0.559). Intraobserver reliability was the highest for the PI and SS, ranging from moderate to good (ICC, 0.718 to 0.896). The lowest intraobserver reliability was seen for the AI (ICC range, 0.026 to 0.545) and pelvic femoral angle (ICC range, 0.035 to 0.828). Surgeon measurements of PT and SS were compared with engineer measurements with extremely poor correlation observed (ICC <0 for all).

CONCLUSION

Surgeon intraobserver and interobserver reliability in making novel radiographic measurements was low compared with traditional radiographic measurements. Surgeon reliability in making traditional measurements of the PT and SS was very poor compared with experienced assessors using software-based measurements.

Cutibacterium colonization of the anterior and lateral thigh

AIMS

Of growing concern in arthroplasty is the emergence of atypical infections, particularly Cutibacterium (formerly Propionibacterium) sp. infections. Currently, the dermal colonization rate of Cutibacterium about the hip is unknown. Therefore, the aim of this study was to investigate colonization rates of Cutibacterium sp. at locations approximating anterior and posterolateral approaches to the hip joint.

METHODS

For this non-randomized non-blinded study, 101 adult patients scheduled for hip or knee surgery were recruited. For each, four 3 mm dermal punch biopsies were collected after administration of anaesthesia, but prior to antibiotics. Prebiopsy skin preparation consisted of a standardized preoperative 2% chlorhexidine skin cleansing protocol and an additional 70% isopropyl alcohol mechanical skin scrub immediately prior to biopsy collection. Two skin samples 10 cm apart were collected from a location approximating a standard direct anterior skin incision, and two samples 10 cm apart were collected from a lateral skin incision (suitable for posterior, direct-lateral, or anterolateral approaches). Samples were cultured for two weeks using a protocol optimized for Cutibacterium.

RESULTS

A total of 23 out of 404 cultures (collected from 101 patients) were positive for a microorganism, with a total of 22 patients having a positive culture (22%). Overall, 15 of the cultures in 14 patients were positive for Cutibacterium sp. (65%), of which Cutibacterium acnes comprised the majority (n = 13; 87%). Other isolated microorganisms include coagulase-negative Staphylococcus (n = 6), Clostridium (n = 1), and Corynebacterium (n = 1). Of all positive cultures, 15 were obtained from the anterior location (65%), of which seven (60%) were from the most proximal biopsy location. However, these findings were not statistically significant (anterior vs lateral, p = 0.076; proximal vs distal, p =0.238).

CONCLUSION

Approximately 14% (14/101) of the patients demonstrated a positive Cutibacterium colonization about the hip, the majority anteriorly. Given the high colonization rate of Cutibacterium, alternative skin preparations for total hip arthroplasty should be considered. Cite this article: Bone Joint J 2020;102-B(7 Supple B):52-56.

The James A. Rand Young Investigator's Award: Traditional Intravenous Fluid vs. Oral Fluid Administration in Primary Total Knee Arthroplasty: A Randomized Trial

BACKGROUND

Optimal perioperative fluid management has not been established in patients undergoing orthopedic surgical procedures. Our purpose was to investigate the effects of perioperative fluid management (ie, preoperative, intraoperative, and postoperative) on patients undergoing total knee arthroplasty (TKA).

METHODS

One hundred thirty patients who met inclusion criteria undergoing primary unilateral TKA were prospectively randomized into traditional (TFG) vs oral (OFG) perioperative fluid management groups. The primary outcome was change in body weight (BW). Secondary outcome measures included knee motion, leg girth, bioelectrical impendence, quadriceps activation, functional outcomes testing, Knee injury and Osteoarthritis Outcome Score JR, VR-12, laboratory values, vital signs, patient satisfaction, pain scores, and adverse events.

RESULTS

The TFG had increased BW the evening of surgery (7.0 ± 4.3 vs 3.0 ± 3.9, P < .0001), postoperative day (POD) #1 (9.1 ± 4.3 vs 4.7 ± 3.9, P < .0001), and POD #2 (6.2 ± 5.0 vs 4.4 ± 4.0, P = .032). Bioelectrical impedance showed less limb edema in the OFG (4.2 ± 29.7 vs 17.8 ± 30.3, P < .0001) on POD #1. Urine specific gravity differences were seen preoperatively between groups (OFG, more hydrated, P = .002). Systolic blood pressure decrease from the baseline was greater in the OFG on arrival to the floor (19.4 ± 13.5 vs 10.6 ± 12.8, P < .0001) and 8 (23.4 ± 13.3 vs 17.0 ± 12.9, P = .006) and 16 (25.8 ± 13.8 vs 25.8 ± 13.8, P = .046) hours after floor arrival. The TFG had more urine output on POD #1 (3369 mL ± 1343 mL vs 2435 mL ± 1151 mL, P < .0001). The OFG were more likely to go home on POD #1 than the TFG (63 vs 56, P = .02).

CONCLUSION

Oral fluid intake with IVF restriction in the perioperative period after TKA may offer short-term benefits with swelling and BW fluctuations. The authors continue to limit perioperative IVFs and encourage patient initiated fluid intake.

Total Knee Arthroplasty Kinematics

Knee kinematics is an analysis of motion pattern that is utilized to assess a comparative, biomechanical performance of healthy nonimplanted knees, injured nonimplanted knees, and various prosthetic knee designs. Unfortunately, a consensus between implanted knee kinematics and outcomes has not been reached. One might hypothesize that the kinematic variances between the nonimplanted and implanted knee might play a role in patient dissatisfaction following TKA. There is a wide range of TKA designs available today. With such variety, it is important for surgeons and engineers to understand the various geometries and kinematic profiles of available prostheses. The purpose of this review is to provide readers with the pertinent information related to TKA kinematics.

Does the Method of Sterile Glove-Opening Influence Back Table Contamination? A Fluorescent Particle Study

BACKGROUND

Surgical site infections (SSI) may result from inadvertent intraoperative contamination events. This study investigated the method of opening surgical gloves onto the operative field (OF) and potential contamination rates.

METHODS

Twenty surgical glove packets were coated with a commercially available fluorescent particle powder. Two methods of glove openings (10 surgical glove packets in each cohort) were investigated: direct drop (DD) onto the OF vs opening and direct hand-off (DH) to a sterile intermediary (SI). Ultraviolet black light was used to quantify fluorescent particles for dispensed glove packets and the OF in both cohorts. The gloves of the SI were inspected in the DH cohort. A previously used contamination scale for fluorescent particle model contamination was employed: 0: no detectable fluorescent particle specks, 1: 1-5 specks, 2: 5-10 specks, 3: 11-100 specks, 4: >100 specks.

RESULTS

The DD cohort had a median OF contamination of 4 (range, 3-4) vs 3 for the DH trials (range, 1-3; P = .001). Likewise, the median glove contamination was higher in the DD cohort, 3 (range, 2-4) vs 1 for DH (range, 0-3; P = .007). Minimal contamination was found on the hands of the SI. Total fluorescent contamination rates, including the gloves of SI in the DH cohort, revealed greater overall contamination in DD (median, 3.5; range, 2-4) vs DH cohort (median, 1; range, 0-3); (P < .001).

CONCLUSION

Using a fluorescent particle model, there is a greater burden of potential contamination from dispensed glove packets and OF with DD vs DH. The DH method did not show significant fluorescent particle contamination on the SI gloves. These data support the use of the opening of gloves via DH over the DD method in total joint arthroplasty to decrease the risk of potential contamination.

Cannabis Use Does Not Affect Outcomes After Total Knee Arthroplasty

BACKGROUND

The self-reported use of cannabis has increased since its recent legalization in several states. The primary purpose of this study is to report total knee arthroplasty (TKA) outcomes in patients using cannabis.

METHODS

Seventy-one patients who underwent a primary unilateral TKA with minimum 1-year follow-up, who self-reported cannabis use, were retrospectively reviewed. The study period was from January 2014 to February 2018 at a single institution. Patients with a history of opioid consumption, alcohol abuse, tobacco, or illicit drug use were excluded. A matched control was conducted based on age, body mass index, gender, smoking status, and insurance type (surrogate of socioeconomic status) in patients with a unilateral TKA who did not report cannabis use. Outcome measures included Knee Society Scores (KSS), range of motion, Veterans RAND-12 mental and physical component scores. No preoperative differences were noted with these measures. Postoperative complications were recorded and reported.

RESULTS

No difference in length of stay was noted between the users (46.9 hours ± 15.7) and nonusers (49.3 hours ± 20.4) (P = .464). In-hospital total morphine equivalents did not differ between the 2 groups (user = 137 ± 104 mg, nonuser = 146 ± 117 mg, P = .634). Postoperative range of motion did not differ between users (128.4° ± 10.4°) and nonusers (126.9° ± 7.5°) (P = .346). No mean differences in follow-up KSS (user = 180.1 ± 24.9, nonuser = 172.0 ± 33.9, P = .106) or total change (user = 61.7 ± 32.8, nonuser = 62.7 ± 30.7, P = .852) in KSS were noted. Likewise, no significant mean differences in Veterans RAND-12 (mental component scores: user = 54.8 ± 9.3, nonuser = 55.9 ± 8.79, P = .472; physical component scores: user = 48.3 ± 9.9, nonuser = 45.8 ± 10.1, P = .145) scores were demonstrated. There were no differences in readmissions (user = 5, nonuser = 4, P = .730) or reoperations (user = 5, nonuser = 2, P = .238).

CONCLUSION

Cannabis use does not appear to influence (adverse or beneficial) short-term outcomes in patients undergoing a primary TKA. Further studies are warranted to determine the efficacy and safety of cannabis as a constituent of multimodal pain management following TKA before endorsements can be made by orthopedic surgeons.

What Is the Value of Component Loosening Assessment of a Preoperatively Obtained Bone Scan Prior to Revision Total Knee Arthroplasty?

BACKGROUND

Bone scintigraphy (BS) is frequently ordered to investigate cause of failure following total knee arthroplasty (TKA). Its correlation of component loosening with intraoperative findings (IFs) at the time of revision TKA (rTKA) has not been well studied. This study investigated correlations between the preoperatively obtained radiologist report (RR) of BS, preoperatively documented surgeon prediction (SP) of component loosening, and operative reports documenting IFs.

METHODS

Our institutional database was retrospectively reviewed for all rTKA done after BS and revealed 96 eligible cases. The RR and SP cohorts were subdivided into all potential combinations of component loosening and were then compared with each other as well as IF. In addition to calculating the percentage correct of RR and SP compared with IF, the levels of agreement between RR and SP were compared using the kappa statistic.

RESULTS

Of the 96 cases, the RR correctly correlated with IF in 35 cases (37%), whereas the SP was correct in 66 cases (69%), indicating the preoperative interpretation of the surgeon regarding component loosening at rTKA was correct more frequently (P < .001). The kappa statistic between RR and IF was only 0.23 (95% confidence interval [CI] = 0.15-0.32), indicating minimal agreement. The kappa statistic between SP and IF was 0.57 (95% = CI 0.46-0.68), indicating weak agreement. Furthermore, the kappa statistic between RR and SP was 0.36 (95% CI = 0.27-0.45), also indicating minimal agreement.

CONCLUSIONS

In rTKA, there is weak agreement regarding component loosening between a radiologist's opinion of a preoperatively obtained bone scan and the surgeon's preoperative interpretation of clinical and radiographic data. While neither reliably accurately predicts what is found at the time of rTKA, the surgeon's preoperative interpretation is more closely correlated with actual IFs of component loosening.

Management of Bone Defects in Revision Total Knee Arthroplasty with Use of a Stepped, Porous-Coated Metaphyseal Sleeve

Background

Revision total knee arthroplasty is a costly operation associated with many challenges including bone loss in the distal end of the femur and proximal end of the tibia^1,2. Reconstruction of bone defects remains a difficult problem that may require more extensive reconstruction techniques to restore mechanical stability and ensure long-term fixation. Use of porous-coated metaphyseal sleeves is a modern technique to address bone deficiency in revision total knee arthroplasty^3,4. Midterm reports have shown excellent survivorship and osseointegration^5-7.

Description

The use of a porous-coated metaphyseal sleeve begins with intramedullary canal reaming to determine the diameter of the diaphyseal-engaging stem. Bone loss is assessed followed by broaching of the tibial and/or femoral metaphyses. Broaching continues until axial and rotational stability are achieved. The sleeve typically occupies most, if not all, of the proximal tibial and distal femoral cavitary osseous defects often encountered during revision total knee arthroplasty. However, a sleeve does not address all distal and posterior femoral condylar bone loss, for which augments are often required.

Alternatives

Previously described methods to address various bone deficiencies include use of morselized or structural bone-grafting, reinforcing screws within cement, metal augments, and metaphyseal cone fixation^8-17.

Rationale

Structural allografts or metal augments remain a suitable option for uncontained metaphyseal defects. Metaphyseal structural allografts may undergo stress-shielding, resorption, and late fracture. Metaphyseal sleeves offer long-term biologic fixation to host bone while creating a stable platform to receive a cemented femoral and/or tibial component⁷. This hybrid combination may provide mechanically protective properties to decrease the loads at the cement-bone interfaces and enhance loads to metaphyseal bone to ensure long-term implant fixation in the setting of substantial bone deficiencies^18-20.

Coronal Alignment in TKA: Traditional Principles Versus New Concepts

Background: Up to 20% of total knee arthroplasty (TKA) patients are not satisfied with their outcome, and coronal alignment is considered an important variable in attaining a well-functioning TKA. Neutral mechanical alignment is not necessarily the anatomic norm and has led some surgeons to advocate a shift in defining and attaining the optimal coronal component alignment. Our aim was to review the different coronal alignment paradigms of TKA and summarize the historical and contemporary outcomes of different alignment techniques.Methods: A systematic review was performed in March 2017 via PubMed using the search terms: coronal alignment, kinematic alignment, and total knee replacement using Boolean “and” in-between terms. Relevant results were then reviewed, analyzed and summarized Conclusions: Early clinical outcomes of kinematically aligned TKAs are promising, but long-term clinical results are unknown. Clinical, laboratory, and retrieval studies suggest that mechanical varus in TKA, especially involving the tibial component, may result in earlier failure. Kinematic alignment with boundaries may be an optimal strategy for patients with pre-operative constitutional varus or congenital tibia vara.

Home-Health-Care Physical Therapy Improves Early Functional Recovery of Medicare Beneficiaries After Total Knee Arthroplasty

BACKGROUND

Home-health-care utilization after total knee arthroplasty (TKA) is increasing. Recent publications have suggested that supervised rehabilitation is not needed to optimize functional recovery after TKA; however, few studies have evaluated patients in home-health-care settings. The objectives of this study were to (1) determine whether physical therapy (PT) utilization is associated with functional improvements for patients in home-health-care settings after TKA and (2) determine which factors are related to utilization of PT.

METHODS

This study was an analysis of Medicare home-health-care claims data for patients treated with a TKA in 2012 who received home-health-care services for postoperative rehabilitation. Multivariable linear regression models were used to evaluate relationships between PT utilization and recovery in activities of daily living (ADLs). Negative binomial regression models were used to determine factors associated with PT utilization.

RESULTS

Records from 5,967 Medicare beneficiaries were evaluated. Low home-health-care PT utilization (≤5 visits) was associated with less improvement in ADLs compared with 6 to 9 visits, 10 to 13 visits, or ≥14 visits. Compared with low home-health-care utilization, utilization of 6 to 9 visits was associated with a 25% greater improvement in ADLs over the home-health-care episode (p < 0.0001); 10 to 13 visits, with a 40% greater improvement (p < 0.0001); and ≥14 visits, with a 50% greater improvement (p < 0.0001). The findings remained robust following adjustments for medical complexity, baseline functional status, and home-health-care episode duration. After adjustment, lower PT utilization was observed for patients receiving home health care from rural agencies (10.7% fewer visits, 95% confidence interval [CI] = 7.9% to 13.7%), those with depressive symptoms (4.8% fewer visits, 95% CI = 1.3% to 8.3%), and those with any baseline dyspnea (5.3% fewer visits, 95% CI = 3.1% to 7.5%).

CONCLUSIONS

Low home-health-care PT utilization was significantly associated with worse recovery in ADLs after TKA for Medicare beneficiaries, after controlling for medical complexity, baseline function, and home-health-care episode duration. Patients who are served by rural agencies or who have higher medical complexity receive fewer PT visits after TKA and may need closer monitoring to ensure optimal functional recovery.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Functional performance, anthropometric parameters and contribution to team success among Italian "Serie A" elite goalkeepers during season 2016-2017

BACKGROUND

Soccer is the world's game, played by more than 120 million people. Different physical abilities, morphological and physiological characteristics are required for different playing positions. The purpose of this study is to describe anthropometric parameters and functional performances of goalkeepers, and these relationship with team success.

METHODS

The study population consisted of 92 professional goalkeepers from the Italian soccer "Serie A" league. Anthropometric measurements and indicators of performance of matches were obtained from the Italian soccer league. Goalkeepers were divided into first-choice and substitutes.

RESULTS

Goalkeepers who played at least one match were significantly older and heavier than those who did not play any game (P<0.0001). Minutes on the pitch, goals conceded, total saves and saves from both play sets and free kicks were significantly higher in the first-choice goalkeepers as compared to substitutes. However, by comparing first-choice with substitutes no significant differences for the ratio between goals against and saves by minutes played were observed. A significant positive correlation between points obtained by the team and ratio of goals conceded by minutes played (R=0.55; P<0.0001) as well as ranking position of the team achieved at the end of the season and the ratio of total saves by minutes played (R=0.51; P=0.001) was observed. A significant but inverse correlation between points obtained by the team and goal conceded was reported (R=-0.80; P<0.0001), as well as point obtained and ratio of total saves by minutes played (R=0.51; P=0.001). A lower ratio of goals conceded by minutes played was a significant predictor of total points achieved by the team (β=0.712, SE=0.15; P<0.0001). Finally, a higher ratio of goal conceded by minutes played was also associated with a higher probability of success for the team at the end of the season. Goalkeepers who completed the season with a ratio of goal against by minutes played greater than 57.5 minutes had an increased probability of leading their team to the first 6 positions of the final ranking (OR=24.7, 95% CI: 2.1-297.3; P=0.01).

CONCLUSIONS

Performance activities of the goalkeepers included in the rosters of the Italian soccer league significantly influenced the success of their team. A lower ratio of goals conceded by minutes played resulted to be the most significant predictor of overall team success. The present research extended previous research underlining the central role of goalkeeper for team success.

Radiographic Changes in Nonoperative Contralateral Knee After Unilateral Total Knee Arthroplasty

BACKGROUND

Some patients perceive symptomatic improvement in the contralateral knee after unilateral total knee arthroplasty (TKA). This so-called "splinting effect" has been observed but has not been radiographically evaluated.

METHODS

A retrospective review of patients with bilateral knee osteoarthritis treated with unilateral TKA was performed. Patients were subcategorized into 2 groups based on whether contralateral TKA was performed within the 2-year period. Contralateral radiographic measurements were performed.

RESULTS

Forty-four of 203 patients had contralateral TKA performed within 2 years. Preoperative parameters were significantly worse in the bilateral group. By 6 weeks postoperatively, mechanical axis plumbline improved approximately 1°, with more change in those patients with preoperative varus alignment. Larger delta changes were also present in bilateral group preoperative to 1-year radiographs for tibiofemoral angle and joint space widening.

CONCLUSION

In patients with bilateral knee osteoarthritis who undergo unilateral TKA, a splinting effect may be present and measurable radiographically with improvement of contralateral mechanical axis plumbline. Further research is necessary to determine whether this improvement may delay contralateral TKA implantation.

Revision Total Knee Arthroplasty for Arthrofibrosis

BACKGROUND

Arthrofibrosis after TKA is a significant cause of patient dissatisfaction. There is little evidence regarding revision arthroplasty in this patient population. The purpose of this study is to evaluate outcomes after revision TKA for arthrofibrosis.

METHODS

We retrospectively reviewed 46 consecutive revision TKAs for arthrofibrosis between 2007 and 2015 with minimum 2-year follow-up. Range of motion (ROM), complication rates, and Knee Society Scores (KSS) were recorded.

RESULTS

Patients were followed for a mean of 59 months. ROM and KSS significantly improved: with flexion improving from 88° to 103° and extension improving from 11° to 3° (P < .001). There was not a relationship between patient or surgical factors and outcomes in this study. The rate of complications was 28.2% with a 17.4% reoperation rate.

CONCLUSION

While revision for arthrofibrosis after TKA can be associated with significant improvements in ROM and KSS, caution is advised given high rates of revisions, reoperations, and complications. Thirty percent of patients in this series had a decrease in one or more component of the KSS or a net decrease in arc of motion after revision surgery.

Midterm Prospective Comparative Analysis of 2 Hard-on-Hard Bearing Total Hip Arthroplasty Designs

INTRODUCTION

Hard-on-hard (HoH) bearing surfaces in total hip arthroplasty (THA) are commonly utilized in younger patients and may decrease mechanical wear compared to polyethylene bearing surfaces. To our knowledge, no study has prospectively compared the 2 most common HoH bearings, ceramic-on-ceramic (CoC) and metal-on-metal (MoM) THA.

MATERIALS AND METHODS

We prospectively enrolled 40 patients to undergo an MoM THA and 42 patients to undergo a CoC THA utilizing the same acetabular component. Patients were followed up for a minimum of 2 years. Comparative outcomes included clinical scores, revision or reoperation for any reason, complication rates, and radiographic outcomes.

RESULTS

The average follow-up was significantly longer in the CoC cohort (94 vs 74 months; P = .005). The CoC cohort had significantly improved Harris Hip Scores (95 vs 84; P = .0009) and pain scores (42 vs 34; P = .0003). The revision (0% vs 31%; P = .0001), reoperation (7.5% vs 36%; P = .004), and complication rates (10% vs 56%; P = .0001) were significantly lower in the CoC cohort. There were no statistically significant differences in radiographic parameters.

CONCLUSION

The clinical outcomes in the CoC cohort exceeded the MoM cohort. It is unlikely that another prospective comparative study of HoH THAs will be conducted. Our midterm results support the use of CoC THA as a viable option that may reduce long-term wear in younger patients. Close surveillance of MoM THA patients is recommended considering the higher failure and complication rates reported in this cohort.

Fracture of the insert cone of a polyethylene liner in a failed posterior-stabilized, rotating-platform total knee arthroplasty

Failures unique to posterior cruciate-substituting total knee prostheses rarely include polyethylene post fractures but have been described. We report a case involving a fracture of the distal insert cone of a rotating-platform (RP) polyethylene liner in a primary total knee arthroplasty. This case highlights a 67-year-old male presenting with new-onset knee pain and recurrent effusions with osteolysis 11 years following placement of a posterior-stabilized, RP total knee arthroplasty. At the time of revision surgery, the polyethylene insert cone was found to be fractured just below the junction between cone and the body of the insert. Liner exchange, synovectomy, and osteolytic-defect curettage and cement packing were performed. One year following revision surgery, the patient is without pain and has returned to function without limitations. Clinicians must be aware of this possible failure with RP prostheses in the setting of pain with a stable knee, recurrent aseptic effusions, and osteolysis.

Direct Anterior Hip Replacement Does Not Pose Undue Radiation Exposure Risk to the Patient or Surgeon

BACKGROUND

The fluoroscopically assisted direct anterior approach for total hip arthroplasty has gained interest in recent years. One of the perceived advantages is the use of fluoroscopy to aid in the positioning of implants. The purpose of this study was to measure the radiation entrance surface dose to anatomically important areas of both patients and surgeons during direct anterior approach total hip arthroplasty.

METHODS

Radiation dosimetry badges were placed at the sternal notch and pubic symphysis of 50 patients undergoing direct anterior approach total hip arthroplasty. Badges were also placed on the surgeons outside of their lead aprons at the level of the thyroid. Three fellowship-trained arthroplasty surgeons were involved in the study. Radiation exposure of each badge was measured after each case (surgeon and patient). The cumulative dose was also calculated for the surgeons. To limit surgeon bias during the study, 50 consecutive direct anterior approach total hip arthroplasties that occurred prior to this study were analyzed for total fluoroscopic dose and time and served as a control group.

RESULTS

Forty-five subjects met study criteria. In the study group, 1 patient had a detectable thyroid exposure equal to 1 mrem. Seven patients had a detectable radiation entrance surface dose at the pubic symphysis (range, 1 to 7 mrem). No radiation entrance surface dose was detectable in the remaining 44 patients at the sternal notch and 38 patients at the pubic symphysis. Surgeons in the study did not experience a detectable radiation entrance surface dose. The mean fluoroscopic time was 13.72 seconds (range, 6.7 to 28.7 seconds). The mean patient radiation exposure was 178 mrem (range, 54 to 526 mrem).

CONCLUSIONS

This study demonstrates that during direct anterior approach total hip arthroplasty, the mean patient entrance surface dose at the pubic symphysis and the sternal notch is not detectable in most patients. The mean patient exposure in this study during direct anterior approach total hip arthroplasty was 178 mrem, which is less than a single pelvic radiograph (600 mrem). No surgeon in our study demonstrated a detectable radiation entrance surface dose. Our data suggest that direct anterior approach total hip arthroplasty typically results in a negligible or very low dose of absorbed radiation exposure to the patient and the surgeon.

CLINICAL RELEVANCE

We believe this study to have clinical relevance because both patients and surgeons have evidence that utilization of fluoroscopy during direct anterior total hip replacement places both parties at a relatively low radiation exposure risk.

Implant Design and Effects on Patellofemoral Crepitus

Background Patellofemoral crepitus is a known complication of posterior stabilized (PS) total knee arthroplasty (TKA). This study compared the incidence of patellofemoral crepitus between two femoral components designs. Materials and Methods Between January 2005 and August 2010, 1,120 patients with complete 2-year follow-up had a PS TKA with two different prosthetic designs (group A, 553 patients; group B, 567 patients). Records were reviewed to identify the incidence of total, symptomatic, and operative patellofemoral crepitus. Results No statistical differences were observed in the incidence of total patellofemoral crepitus (group A 14.1%, group B 14.5%; p = 0.932) or symptomatic patellofemoral crepitus (group A 5.6%, group B 4.2%; p = 0.334). The incidence of operative crepitus was greater in group A (3.3%) than in group B (1.3%; p = 0.026). Analysis of mobile versus fixed bearing designs showed a higher incidence of total patellofemoral crepitus in mobile bearing TKA (16.04 vs. 4.93%; p = 0.006) within group B only. Conclusion Femoral component design with a smoother intercondylar box transition zone resulted in a lower incidence of operative patellofemoral crepitus. No statistical differences were noted regarding the incidence of total and symptomatic patellofemoral crepitus. Mobile bearing TKA exhibited greater total crepitus within group B. Level of Evidence Level III.

Enhancing Recovery After Total Knee Arthroplasty

There have been multiple successful efforts to improve and shorten the recovery period after elective total joint arthroplasty. The development of rapid recovery protocols through a multidisciplinary approach has occurred in recent years to improve patient satisfaction as well as outcomes. Bundled care payment programs and the practice of outpatient total joint arthroplasty have provided additional pressure and incentives for surgeons to provide high-quality care with low cost and complications. In this review, the evidence for modern practices are reviewed regarding patient selection and education, anesthetic techniques, perioperative pain management, intraoperative factors, blood management, and postoperative rehabilitation.

Influence of Hip Abductor Strength on Functional Outcomes Before and After Total Knee Arthroplasty: Post Hoc Analysis of a Randomized Controlled Trial

BACKGROUND

Total knee arthroplasty (TKA) is associated with declines in hip abductor (HA) muscle strength; however, a longitudinal analysis demonstrating the influence of TKA on trajectories of HA strength change has not been conducted.

OBJECTIVE

The purpose of this study was to quantify changes in HA strength from pre-TKA through 3 months post-TKA and to characterize the relationship between HA strength changes and physical performance.

DESIGN

This study is a post hoc analysis of a randomized controlled trial.

METHODS

Data from 162 participants (89 women, mean age = 63 y) were used for analysis. Data were collected by masked assessors preoperatively and at 1 and 3 months following surgery. Outcomes included: Timed "Up and Go" test (TUG), Stair Climbing Test (SCT), Six-Minute Walk Test (6MWT), and walking speed. Paired t tests were used for between- and within-limb comparisons of HA strength. Multivariable regression was used to determine contributions of independent variables, HA and knee extensor strength, to the dependent variables of TUG, SCT, 6MWT, and walking speed at each time point.

RESULTS

Hip abductor strength was significantly lower in the surgical limb pre-TKA (mean = 0.015; 95% CI = 0.010-0.020), 1 month post-TKA (0.028; 0.023-0.034), and 3 months post-TKA (0.02; 0.014-0.025) compared with the nonsurgical limb. Hip abductor strength declined from pre-TKA to 1 month post-TKA (18%), but not at the 3-month time point (0%). Hip abductor strength independently contributed to performance-based outcomes pre-TKA; however, this contribution was not observed post-TKA.

LIMITATIONS

The post hoc analysis prevents examining all outcomes likely to be influenced by HA strength.

CONCLUSIONS

Surgical limb HA strength is impaired prior to TKA, and worsens following surgery. Furthermore, HA strength contributes to performance-based outcomes, supporting the hypothesis that HA strength influences functional recovery.

Midterm Clinical and Radiographic Results of Mobile-Bearing Revision Total Knee Arthroplasty

BACKGROUND

Constrained implants are frequently required in revision total knee arthroplasty (TKA) and are associated with an increase in aseptic component loosening and damage or wear to the constraining mechanisms, compared with primary TKA. The purpose of the following study was to evaluate the midterm clinical and radiographic results including the incidence of bearing complications in a group of patients undergoing revision TKA using mobile-bearing revision TKA implants.

METHODS

We retrospectively reviewed 316 consecutive mobile-bearing revision TKAs performed at 2 centers between 2006 and 2010. There were 183 women and 133 men with a mean age of 66 years. The patients were evaluated clinically using the Knee Society scores. A radiographic analysis was performed. Bearing specific complications (ie, instability or dislocation) were recorded.

RESULTS

Patients were followed-up for a minimum of 24 months and a median of 59.88 months (range 24-121.2). The average Knee Society knee score and function scores increased from 40.8 and 47.9 points preoperatively to 80 points and 70.3 points, respectively (P < .01). The average knee flexion improved from 105.6° preoperatively to 117.4° postoperatively (P < .01). Eight patients required subsequent implant revision. No cases of bearing complications were observed.

CONCLUSION

Revision TKA using mobile-bearing revision components demonstrated favorable midterm clinical and radiographic results with no occurrence of bearing instability or dislocation. Longer follow-up is required to evaluate for potential advantages of mobile-bearings over fixed-bearing revision components in terms of polyethylene wear reduction, reduced stress transmission across fixation interfaces, and reduced stress on the polyethylene post.

Metal Artifact Reduction Sequence MRI Abnormalities in Asymptomatic Patients with a Ceramic-on-Polyethylene Total Hip Replacement

BACKGROUND

Magnetic resonance imaging (MRI) is a commonly utilized screening modality in patients with a metal-on-metal (MoM) total hip replacement. The prevalence of clinically important fluid collections may be overestimated since these collections have been reported to occur in asymptomatic patients with MoM and other bearing surfaces. The purpose of this study was to determine the frequency and types of MRI-documented adverse local tissue reactions in asymptomatic patients with a ceramic-on-polyethylene (CoP) total hip replacement.

METHODS

Forty-four patients (50 hips) with a minimum 2-year follow-up after total hip arthroplasty with CoP implants and a Harris hip score of >90 were enrolled in this study. The inclusion criteria were the absence of hip pain and the availability of appropriate follow-up radiographs. All patients underwent a metal artifact reduction sequence (MARS) MRI scan to determine the presence of fluid collections in asymptomatic patients with a CoP bearing surface.

RESULTS

Fluid collections were observed in 9 (18%) of 50 asymptomatic hips in this cohort. There were 5 hips with intracapsular synovitis, and 2 of these hips had a thickened synovium. Extra-articular fluid collections with direct intracapsular communication were identified in 4 additional hips. Two of these hips had a thickened synovium. No signs of osteolysis or evidence of adverse local tissue reactions were noted on radiographs at the most recent follow-up.

CONCLUSIONS

This study revealed that fluid collections are not uncommon after total hip arthroplasty with CoP implants. Synovial thickening may be present and is more prevalent than has been reported in previous studies involving metal-on-polyethylene (MoP) bearing surfaces. The clinical importance and natural history of these findings remain unknown.

LEVEL OF EVIDENCE

Diagnostic Level IV. See Instructions for Authors for a complete description of levels of evidence.