Socioeconomic Indices Are Associated With Increased Resource Utilization, But Not 90-Day Complications Following Total Hip and Knee Arthroplasty.

INTRODUCTION: Socioeconomic disadvantage has been associated with negative outcomes following total hip (THA) and knee arthroplasty (TKA). The Area Deprivation Index (ADI) and Distressed Community Index (DCI) are composite rankings that score socioeconomic status (SES) using patients' home addresses. The purpose of this study was to examine the association of ADI and DCI with outcomes following THA and TKA while controlling for potential confounding covariates. METHODS: A series of 4,146 consecutive patients undergoing primary THA and TKA between January 2018 and May 2023 were queried from our institutional total joint registry. The 90-day medical and surgical complications and resource utilization were collected. The ADI and DCI scores were obtained for each patient, and the association between these scores and postoperative outcomes was analyzed. RESULTS: The ADI and DCI were both associated with patient age, sex, race, comorbidity burden, and smoking status. After controlling for these variables, higher ADI and DCI scores were associated with increased length of stay (P = 0.003 and P = 0.008, respectively), but were not associated with the occurrence of any 90-day complication, reoperation, or revision. CONCLUSION: The SES, as quantified by ADI and DCI, was associated with multiple known risk factors for complications following THA and TKA, but was not independently associated with complications, reoperations, or revision surgeries at 90 days postoperatively. While convenient metrics for the quantification of SES, in some populations, ADI and DCI may not be independently associated with detrimental outcomes following THA and TKA.

Central Sensitization: The Missing Link Between Psychological Distress and Poor Outcome Following Primary Total Knee Arthroplasty.

BACKGROUND: While preoperative psychological distress is known to predict risk for worse total knee arthroplasty (TKA) outcomes, distress may be too broad and nonspecific a predictor in isolation. We tested whether there are distinct preoperative TKA patient types based jointly on psychological status and measures of altered pain processing that predict adverse clinical outcomes. METHODS: In 112 TKA patients, we preoperatively assessed psychological status (depression, anxiety, and catastrophizing) and altered pain processing via a simple quantitative sensory testing protocol capturing peripheral and central pain sensitization. Outcomes (pain, function, opioid use) were prospectively evaluated at 6 weeks and 6 months after TKA. Cluster analyses were used to empirically identify TKA patient subgroups. RESULTS: There were 3 distinct preoperative TKA patient subgroups identified from the cluster analysis. A low-risk (LR) group was characterized by low psychological distress and low peripheral and central sensitization. In addition, 2 subgroups with similarly elevated preoperative psychological distress were identified, differing by pain processing alterations observed: high-risk centralized pain and high-risk peripheral pain. Relative to LR patients, high-risk centralized pain patients displayed significantly worse function and greater opioid use at 6 months after TKA (P values <.05). The LR and high-risk peripheral pain patient subgroups had similar 6-month outcomes (P values >.05). CONCLUSIONS: Among patients who have psychological comorbidity, only patients who have central sensitization were at elevated risk for poor functional outcomes and increased opioid use. Central sensitization may be the missing link between psychological comorbidity and poor TKA clinical outcomes. Preoperative testing for central sensitization may have clinical utility for improving risk stratification in TKA patients who have psychosocial risk factors.

Age-Adjusted Modified Frailty Index Predicts 30-Day Complications and Mortality in Aseptic Revision Total Hip and Knee Arthroplasty.

BACKGROUND: The age-adjusted modified frailty index (aamFI) has been demonstrated to effectively predict postoperative complications and healthcare resource utilization in patients undergoing primary total joint arthroplasty. The purpose of this study was to evaluate the applicability of aamFI in patients undergoing aseptic revision total hip (rTHA) and knee arthroplasty (rTKA). METHODS: A national database was queried for patients undergoing aseptic rTHA and rTKA from 2015 to 2020. A total of 13,307 rTHA and 18,762 rTKA cases were identified. The aamFI was calculated by adding 1 additional point for age ≥73 years to the previously described 5-item modified frailty index (mFI-5). The area under the curve was calculated and compared to compare predictive accuracy between mFI-5 and aamFI. Logistic regression was used to investigate the relationship between aamFI and 30-day complications. RESULTS: The incidence of incurring any (≥1) complication increased from 15% for aamFI 0 to 45% for aamFI ≥5 after rTHA and from 5 to 55% after rTKA. Patients who had an aamFI ≥3 (reference aamFI = 0) had increased odds (rTHA: odds ratio (OR) 3.5, 95% confidence interval (CI) 2.9 to 4.1, P < .001; rTKA: OR 4.2, 95% CI 4.4 to 5.1, P < .001) of incurring at least 1 complication. The aamFI, compared to mFI-5, was a more accurate predictor of any complication (rTHA P < .001; rTKA P < .001) and 30-day mortality (rTHA P < .001; rTKA P < .003). CONCLUSION: The aamFI is an excellent predictor of complications in patients undergoing rTHA and rTKA. The addition of chronological age to the previously described mFI-5 improves the predictive value of this simple metric.

Is a Failed Spinal Attempt Associated With a Worse Clinical Course Following Primary Total Hip and Knee Arthroplasty?

BACKGROUND: Spinal anesthesia (SA) is the preferred anesthesia modality for total joint arthroplasty (TJA). However, studies establishing SA as preferential may be subject to selection bias given that general anesthesia (GA) is often selectively utilized on more difficult, higher-risk operations. The optimal comparison group, therefore, is the patient converted to GA due to a failed attempt at SA. The purpose of this study was to determine risk factors and outcomes following failed SA with conversion to GA during primary total hip arthroplasty (THA) or total knee arthroplasty (TKA). METHODS: A consecutive cohort of 4,483 patients who underwent primary TJA at our institution was identified (2,004 THA and 2,479 TKA). Of these patients, 3,307 underwent GA (73.8%), 1,056 underwent SA (23.3%), and 130 patients failed SA with conversion to GA (2.90%). Primary outcomes included rescue analgesia requirement in the postanesthesia care unit (PACU), time to ambulation, pain scores in the PACU, estimated blood loss, and 90-day complications. RESULTS: Risk factors for SA failure included older age and a higher comorbidity burden. Failure of SA was associated with increased estimated blood loss, rescue intravenous opioid use, and time to ambulation when compared to the successful SA group in both THA and TKA patients (P < .001). The anesthesia modality was not associated with significant differences in PACU pain scores. The 90-day complication rate was similar between the failed SA and GA groups. There was a higher incidence of postoperative pain prompting unplanned visits and thromboembolism when comparing failed SA to successful SA in both THA and TKA patients (P < .05). CONCLUSIONS: In our series, patients who had failed SA demonstrated inferior outcomes to patients receiving successful SA and similar outcomes to patients receiving GA who did not have an SA attempt. This emphasizes the importance of success in the initial attempt at SA for optimizing outcomes following TJA.

The Impact of Frailty Is Age Dependent in Patients Undergoing Primary Total Knee Arthroplasty: The Age-Adjusted Modified Frailty Index.

BACKGROUND: Frailty is a well-established risk factor in patients undergoing total knee arthroplasty (TKA). How age modifies the impact of frailty on outcomes in these patients, however, remains unknown. In this study, we aimed to describe and evaluate the applicability of a novel risk stratification tool-the age-adjusted modified Frailty Index (aamFI)-in patients undergoing TKA. METHODS: A national database was queried for all patients undergoing primary TKA from 2015 to 2019. There were 271,271 patients who met inclusion criteria for this study. First, outcomes were compared between chronologically young and old frail patients. In accordance with previous studies, the 75th percentile of age of all included patients (73 years) was used as a binary cutoff. Then, frailty was classified using the novel aamFI, which constitutes the 5-item mFI with the addition of 1 point for patients ≥73 years. Multivariable logistic regressions were then used to investigate the relationship between aamFI and postoperative outcomes. RESULTS: Frail patients ≥73 years had a higher incidence of complications compared to frail patients <73 years. There was a strong association between aamFI and complications. An aamFI of ≥3 (reference aamFI of 0) was associated with an increased odds of 30-day mortality (odds ratio [OR] 8.6, 95% CI 5.0-14.8), any complication (OR 3.1, 95% CI 2.9-3.3), deep vein thrombosis (OR 1.5, 95% CI 1.2-1.8), and nonhome discharge (OR 6.1, 95% CI 5.8-6.4; all P < .001). CONCLUSION: Although frailty negatively influences outcomes following TKA in patients of all ages, chronologically old, frail patients are particularly vulnerable. The aamFI accounts for this and represents a simple, but powerful tool for stratifying risk in patients undergoing primary TKA.

Trends in Total Knee Arthroplasty Cementing Technique Among Arthroplasty Surgeons-A Survey of the American Association of Hip and Knee Surgeons Members.

BACKGROUND: Aseptic loosening persists as one of the leading causes of failure following cemented primary total knee arthroplasty (TKA). Cement technique may impact implant fixation. We hypothesized that there is variability in TKA cement technique among arthroplasty surgeons. METHODS: A 28-question survey regarding variables in surgeons' preferred TKA cementation technique was distributed to 2,791 current American Association of Hip and Knee Surgeons (AAHKS) members with a response rate of 30.8% (903 respondents). Patterns of responses were analyzed by grouping respondents by their answers to certain questions including cementing technique, tibial cement location, and femoral cement location. RESULTS: A total of 73.5% reported performing at least 7 of 8 of the highest consensus techniques, including vacuum mixing (79.9%), using two bags (76.1%), tibial implant first (95.2%), single-stage cementing (96.9%), compression of the implants in extension (91.7%), and use of a tourniquet (84.3%). Medium and high viscosity cement was most commonly used (37.9 and 37.8%, respectively). Finger pressurization was most common (76.1%) compared to a gun (29.8%). There were 26.5% of respondents performing 6 or fewer of the most common majority techniques and seemed to perform other less common techniques (eg, use of a single bag of cement, trialing or closure prior to cement curing, and heating to accelerate cement curing). Cement was most commonly applied to the entire bone and implant surface on both the tibia (46.4%) and femur (47.7%), leaving much variation in the remaining cement application location responses. DISCUSSION: There appears to be variability in cemented TKA technique among arthroplasty surgeons. There were 26.5% of respondents performing less of the majority techniques and also performed other additional low-response rate techniques. Further studies that look at the impacts of variation in techniques on outcomes may be warranted. Our study demonstrates the need for defining best practices for cement technique given the substantial variability identified.

Could Novel Radiographic Findings Help Identify Aseptic Tibial Loosening?

BACKGROUND: Aseptic loosening following total knee arthroplasty remains one of the leading causes of long-term failure. Radiographic identification of loose implants can be challenging with standard views. The purpose of this study was to compare the incidence of novel radiographic findings of anterior heterotopic bone formation and medial or lateral cyst formation in patients who have aseptic loosening to patients who have well-fixed implants. METHODS: A retrospective radiographic review was performed on 48 patients' revised secondary to aseptic tibial loosening. This cohort was compared to two additional cohorts; 48 patients returning for routine postoperative follow-up (control 1), and 48 patients revised secondary to infection or instability who had well-fixed implants (control 2). RESULTS: There were 41 of 48 (85%) patients who had implant loosening and were noted to have anterior heterotopic bone formation compared to 1 of 48 (2%) patients in control 1 and 3 of 48 (6%) patients in control 2 (P ≤ .0001). There were 43 of 48 (90%) patients who had implant loosening and had medial cyst formation compared to 3 of 48 (6%) patients in control 1 and 5 of 48 (10%) in control 2 (P ≤ .0001). There were 42 of 48 (88%) patients who had implant loosening and had lateral cyst formation compared to 2 of 48 (4%) patients in control 1 and 4 of 48 (8%) in control 2 (P ≤ .0001). CONCLUSION: In this study, we describe novel radiographic findings of anterior heterotopic bone formation and cysts that develop in patients who have aseptic loosening following primary total knee arthroplasty. We believe that these radiographic features may lead to easier identification of aseptic loosening.

The Impact of Frailty on Outcomes Following Primary Total Hip Arthroplasty in Patients of Different Sex and Race: Is Frailty Equitably Detrimental?

BACKGROUND: Whether frailty impacts total hip arthroplasty (THA) patients of different races or sex equally is unknown. This study aimed to assess the influence of frailty on outcomes following primary THA in patients of differing race and sex. METHODS: This is a retrospective cohort study utilizing a national database (2015-2019) to identify frail (≥2 points on the modified frailty index-5) patients undergoing primary THA. One-to-one matching for each frail cohort of interest (race: Black, Hispanic, Asian, versus White (non-Hispanic), respectively; and sex: men versus women) was performed to diminish confounding. The 30-day complications and resource utilizations were then compared between cohorts. RESULTS: There was no difference in the occurrence of at least 1 complication (P > .05) among frail patients of differing race. However, frail Black patients had increased odds of postoperative transfusion (odds ratio [OR]: 1.34, 95% confidence interval [CI]: 1.02-1.77), deep vein thrombosis (OR: 2.61, 95% CI: 1.08-6.27), as well as >2-day hospitalization and nonhome discharge (P < .001). Frail women had higher odds of having at least 1 complication (OR: 1.67, 95% CI: 1.47-1.89), nonhome discharge, readmission, and reoperation (P < .05). Contrarily, frail men had higher 30-day cardiac arrest (0.2% versus 0.0%, P = .020) and mortality (0.3 versus 0.1%, P = .002). CONCLUSION: Frailty appears to have an overall equitable influence on the occurrence of at least 1 complication in THA patients of different races, although different rates of some individual, specific complications were identified. For instance, frail Black patients experienced increased deep vein thrombosis and transfusion rates relative to their non-Hispanic White counterparts. Contrarily, frail women, relative to frail men, have lower 30-day mortality despite increased complication rates.

Mid-term Follow Up of a Highly Porous Acetabular Component for Primary Total Hip Arthroplasty.

INTRODUCTION: As implant technology has continued to improve over the past decade, there has been an increase in the utilization of highly porous metal substrate acetabular components for primary total hip arthroplasty (THA). These implants have several theoretical benefits including a lower modulus of elasticity, which may result in a reduction in stress shielding, a higher coefficient of friction, which may enable better initial implant fixation, as well as higher porosity that may facilitate improved biological fixation. Although these components are implanted frequently, there are some studies that have posed concerns regarding radiographic evidence of loosening. Therefore, the purpose of this study was to assess: 1) The quality of fixation of porous metal acetabular components based on radiographs; 2) clinical outcomes; and 3) revision rates. MATERIALS AND METHODS: A total of 159 patients (169 hips) who had undergone a primary THA utilizing a porous metal primary acetabular cup with minimum two-year follow up were assessed. The study cohort consisted of 51% women, had a mean age of 65 years (range, 30 to 92 years), a mean body mass index (BMI) of 29kg/m2 (range, 15 to 54), and a mean follow up of approximately four years (range, three to six years). Acetabular revision for component failure was documented. Radiographic assessments were independently performed by two fellowship-trained arthroplasty surgeons to determine implant stability and radiolucencies. Clinical evaluations were made by assessing the hip disability and osteoarthritis outcome score (HOOS-Jr) survey scores. Failure was defined as the need to revise the acetabular component, for either septic or aseptic pathology. RESULTS: At final follow up, one patient had definitive loosening, one had probable loosening, and three patients had possible loosening. Only 3.0% had radiolucencies or radiosclerotic lesions in at least one zone. Of these patients, three developed progressive radiolucencies. All patients achieved excellent postoperative HOOS-Jr scores, and no significant differences were noted between patients who did not have loosening compared to patients who had possible or probable loosening. Only two patients underwent revision for aseptic loosening of the cup (success rate for this implant was 98.8% [2/169]). DISCUSSION: There is a paucity of studies focused on the results of this porous metal substrate acetabular component, with some of the current literature reporting conflicting outcomes. Our study reported a low acetabular revision rate of only 1.2% at an approximate mean follow up of four years. The incidence of radiolucencies and progressive radiolucencies were lower (3.0%) than has been found in some studies. Overall, the results of this study support the utilization of this acetabular component in appropriately indicated patients. CONCLUSION: These data show a low rate of acetabular revision at mean four-year follow up.

Varus Collapse in Total Knee Arthroplasty: Does Fixation or Bone Fail First?

INTRODUCTION: Aseptic tibial loosening is now considered the most common reason that total knee arthroplasties (TKA) fail long term. There are unique subsets of patients that fail into varus alignment of the tibial tray with collapse of the medial proximal tibia. It is currently unknown if the implant fixation fails first or if the proximal medial tibia collapses first. MATERIALS: We performed a retrospective analysis of 88 patients that were revised at our institution secondary to aseptic varus collapse of the proximal tibia. Two fellowship-trained arthroplasty surgeons performed a retrospective analysis on sequential precollapse radiographs in each patient to determine which failed first: the implant fixation (implant-cement or cement-bone interface) or the medial proximal tibia. DISCUSSION: 36/88 (40.9%) patients had a series of precollapse radiographs that could be reviewed. Failure at the implant-cement interface before varus collapse in 23 vs 22 patients, failure at the implant-cement and cement-bone interface before varus collapse in two patients, and contemporaneous failure at the implant-cement interface and varus collapse in 11 vs 12 patients were identified by reviewers one and two, respectively. CONCLUSION: The most frequent mechanism of failure identified was failure of the implant-cement interface followed by subsequent medial tibial varus collapse. Improving implant fixation may decrease the incidence of this unique failure mechanism. We advocate the use of supplemental stem fixation in high-risk patients and optimal cement techniques for all patients as methods of potentially avoiding tibial varus collapse, one of the most frequent modes of long-term failure.

Chitranjan S. Ranawat Award: Motion During Total Knee Cementing Significantly Decreases Tibial Implant Fixation Strength.

BACKGROUND: Aseptic tibial loosening following primary total knee arthroplasty persists despite technique and device-related advancements. The mechanisms for this mode of failure are not well understood. We hypothesized that knee movement while the cement was curing dispersed lipids at the implant-cement interface and would result in decreased tibial fixation strength. METHODS: A cadaveric study was performed utilizing 32 torso-to-toe specimens (64 knees). Four contemporary total knee arthroplasty designs were evaluated. Each implant design was randomly assigned to a cadaveric specimen pair with side-to-side randomization. Specimen densitometry was recorded. Each tibial implant was cemented using a standard technique. On one side, the tibial component was held without motion following impaction until complete cement polymerization. The contralateral knee tibial implant was taken through gentle range of motion and stability assessment 7 minutes after cement mixing. Axial tibial pull-out strength and interface failure examination was performed on each specimen. RESULTS: The average pull-out strength for the no motion cohort (5,462 N) exceeded the motion cohort (4,473 N) (P = .001). The mean pull-out strength between implant designs in the no motion cohort varied significantly (implant A: 7,230 N, B: 5,806 N, C: 5,325 N, D 3,486 N; P = .007). Similarly, the motion cohort inter-implant variance was significant (P ≤ .001). Intra-implant pull-out strength was significantly higher in implant A than D. The average pull-out strength was significantly lower in specimens that failed at the implant-cement interface vs bone failures (4,089 ± 2,158 N vs 5,960 ± 2,010 N, P < .0025). CONCLUSION: Knee motion during cement polymerization is associated with significant decreases in tibial implant fixational strength. Reduction in implant pull-out strength was identified with each implant design with motion and varied between designs. Across all tested designs, we recommend limiting motion while cementing the tibial implant to improve fixation strength.

The Age-Adjusted Modified Frailty Index: An Improved Risk Stratification Tool for Patients Undergoing Primary Total Hip Arthroplasty.

BACKGROUND: Frailty and increasing age are well-established risk factors in patients undergoing total hip arthroplasty (THA). However, these variables have only been considered independently. This study assesses the interplay between age and frailty and introduces a novel age-adjusted modified frailty index (aamFI) for more refined risk stratification of THA patients. METHODS: The American College of Surgeons National Surgical Quality Improvement Program database was queried from 2015 to 2019 for patients undergoing primary THA. First, outcomes were compared between chronologically younger and older frail patients. Then, to establish the aamFI, one additional point was added to the previously described mFI-5 for patients aged ≥73 years (the 75th percentile for age in our study population). The association of aamFI with postoperative complications and resource utilization was then analyzed categorically. RESULTS: A total of 165,957 THA patients were evaluated. Older frail patients had a higher incidence of complications than younger frail patients. Regression analysis demonstrated a strong association between aamFI and complications. For instance, an aamFI of ≥3 (compared to aamFI of 0) was associated with an increased odds of mortality (OR: 22.01, 95% confidence interval [CI] 11.62-41.68), any complication (OR: 3.50, 95% CI 3.23-3.80), deep vein thrombosis (OR: 2.85, 95% CI 2.03-4.01), and nonhome discharge (OR 9.61, 95% CI 9.04-10.21; all P < .001). CONCLUSION: Chronologically, older patients are impacted more by frailty than younger patients. The aamFI accounts for this and outperforms the mFI-5 in prediction of postoperative complications and resource utilization in patients undergoing primary THA.

Where Is the "Weak Link" of Fixation in Contemporary Cemented Total Knee Replacements?

BACKGROUND: Aseptic tibial loosening is a frequent cause of long-term failure following primary cemented total knee replacement. Failure of the tibial implant can occur at the implant-cement interface or at the cement-bone interface. Currently, it is unknown at which interface failure occurs in cases of aseptic tibial loosening. The following study was designed to determine which interface represents the "weak link" for tibial implant fixation. METHODS: We performed a retrospective analysis of 149 patients who were revised secondary to aseptic tibial loosening at our institution from 2005 to 2017. Operative reports and radiographs were reviewed on each patient to determine the location and pattern of fixation failure. RESULTS: Implant failure was more prevalent at the implant-cement than cement-bone interface, 140/149 (94.0%) vs 9/149 (6.0%). Additionally, we noted 2 distinct patterns of failure in patients that loosened at the implant-cement interface. Ninety of 140 (64.3%) patients developed varus collapse pattern of failure. Forty-nine of 140 (35.0%) patients developed failure between the implant-cement interface without angulation. All 149 patients had heterotopic bone formation anterior to the tibial baseplate, which was consistent regardless of which interface failed. CONCLUSION: The most frequent interface failure identified in our study was at the implant-cement interface, 140/149 (94.0%). This finding has substantial clinical ramifications. Because failure was predominantly at the implant-cement interface there may be design opportunities for increasing implant fixation to cement. Implants with improved undersurface tibial tray features may be necessary to mitigate the risk of failure at this interface, especially in overly active patients or those with elevated body mass indices.

Radiologist Overreads of Intraoperative Radiographs-Value or Waste?

BACKGROUND: All aspects of the arthroplasty pathway must be scrutinized to maximize value and eliminate unnecessary cost. Radiology providers' contracts with hospitals often call for readings of all radiographs. This policy has little effect on patient care when intraoperative radiographs are taken and used to make real-time decisions. In order to determine the value of radiologist overreads, we asked 3 questions: what was the delay between the time an intraoperative radiograph was taken and time the report was generated, were the overreads accurate, and what is the associated cost? METHODS: Two hundred hip and knee radiograph reports generated over 6 months during 391 cases were reviewed. The time the report was dictated was compared to the time taken and time of surgery completion. To determine accuracy, each overread was rated as accurate or inaccurate. The cost of the overread was determined by multiplying the number of radiographs times the radiology fee less the technical fee. RESULTS: Median delay between taking the radiograph and filing the report was 45 minutes (range, 0-9778 minutes). Only 31.5% were filed before completion of the procedure. And 18.0% (36/200) were considered inaccurate despite lenient criteria. The reading fee for hip radiographs was $52.00, and for knee radiographs was $38.00, representing a total cost of $10,182 in our select series. This cost projects to $43,614 annually at our facility. CONCLUSION: Radiology overreads of intraoperative radiographs have no effect on real-time decision-making. In the era of value-based care, payors should stop paying for overreads and reimburse providers who actually read the films intraoperatively.

Does Change in ESR and CRP Guide the Timing of Two-stage Arthroplasty Reimplantation?

BACKGROUND: Two-stage reimplantation arthroplasty is a commonly used approach for treating chronic periprosthetic joint infections. A prereimplantation threshold value of erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) to determine infection eradication and the proper timing of reimplantation remains ill defined. We theorized that rather than a specific numeric threshold, a percentage of improvement in these serology markers might improve diagnostic accuracy in determining the timing of reimplantation. QUESTION/PURPOSES: We investigated if (1) the percent, or delta, change in ESR and CRP values from preresection to prereimplantation ([INCREMENT]ESR, [INCREMENT]CRP) is a useful marker of infection eradication and (2) whether the initial PJI causative organism (resistant, nonresistant, or culture-negative) is associated with serum ESR and CRP values before and after treatment with an antibiotic spacer and parenteral antibiotic therapy. METHODS: We retrospectively reviewed 300 patients, nine of whom were lost to followup, treated with a two-stage revision THA or TKA protocol between 2005 and 2014 from two separate institutional arthroplasty registries. Serum ESR and CRP values were recorded at two designated points: (1) preresection and (2) after 6 weeks of intravenous antibiotic therapy with a drug-eluting spacer and completion of an organism-specific intravenous antibiotic regimen. Patient records were reviewed electronically for causative species of infection, revision surgeries, and recurrent/persistent infection based on Musculoskeletal Infection Society criteria for a minimum of 2 years. Forty-eight of 291 patients (16%) underwent a revision procedure for recurrent or persistent infection, whereas 31 patients (10%) were revised for noninfectious reasons. The [INCREMENT]ESR, [INCREMENT]CRP, culture results, and patient demographics were recorded and analyzed with receiver operator curves controlling for American Society of Anesthesiologists (ASA) class. RESULTS: Receiver operator characteristic area under the curves (AUC) demonstrated that both the [INCREMENT]ESR (AUC = 0.581) and [INCREMENT]CRP (AUC = 0.539) percentages were poor markers of recurrent or persistent infection. When comparing preresection with prereimplantation values, the median percent [INCREMENT]ESR was 50% (interquartile range [IQR], 17%-77%) for those patients who remained infection-free versus 59% (IQR, 29%-78%) for those who developed reinfection (p = 0.540). The median percent [INCREMENT]CRP was 77% (IQR, 47%-92%) for those patients who remained infection-free versus 79% (IQR, 46%-95%) for those who experienced reinfection (p = 0.634). Although no significant differences were found between organism type and CRP values at the two time points, the preresection ESR level was higher in patients infected with resistant bacteria (median, 69; IQR, 60%-85%) compared with nonresistant organisms (median, 55; IQR, 33%-83%; p = 0.020). CONCLUSIONS: The percent change in serum ESR and CRP inflammatory markers before and after two-stage reimplantation for PJI was not associated with reinfection risk when controlling for ASA class. Although a return to normal serology infrequently occurs before reimplantation, [INCREMENT]ESR and [INCREMENT]CRP provide no additional diagnostic accuracy to determine the timing of reimplantation. Furthermore, the pre- and postresection serology values have no meaningful relationship to resistant or nonresistant pathogens. Decisions for reimplantation must take into account multiple variables rather than a specific threshold change in serum inflammatory markers. LEVEL OF EVIDENCE: Level III, diagnostic study.

Revisions of Modular Metal-on-metal THA Have a High Risk of Early Complications.

BACKGROUND: The risk of early complications is high after monoblock acetabular metal-on-metal (MoM) THA revisions. However, there is a paucity of evidence regarding clinical complications after isolated head-liner exchange of modular MoM THA. QUESTIONS/PURPOSES: The purposes of this study were (1) to describe the frequency of early complications after an isolated head-liner exchange revision of modular MoM THA; and (2) to determine whether patients who experienced complications or dislocation after head-liner exchanges had higher serum chromium (Cr) or cobalt (Co) ion levels than those who did not. METHODS: A review of our institution's total joint registry retrospectively identified 53 patients who underwent 54 liner exchange revisions of a modular acetabular MoM THA. The study period was from April 2008 to April 2016 at a single tertiary care center. During this period, isolated head-liner exchanges (rather than more extensive revisions) were performed in patients if they did not have evidence of loosening of the acetabular or femoral components. Reasons for revision surgery included pain, mechanical symptoms, radiographic evidence of osteolysis, elevated serum metal ions, and MRI abnormalities with 40 of the 54 hips having pain or mechanical symptoms and 38 of 54 hips having multiple reasons for revision before surgery. Patients were excluded if they did not meet the minimum postrevision followup or had the modular liner exchange secondary to infection. All revisions were from a single manufacturer with one head-liner exchange of a MoM THA from another manufacturer excluded during the study period. The mean time from index MoM THA to modular exchange was 96 (SD ± 36) months. Because the focus of this study was early complications, we had a minimum 90-day followup duration for inclusion. Mean followup after revision was 15 months (SD ± 12); a total of 56% (30 of 54) had followup of at least 12 months' duration. Complications (dislocation, infection) and reoperations were obtained by chart review performed by individuals other than the treating physician(s). Serum metal ion levels were obtained before head-liner exchange. The median serum Cr and Co levels were 6 µg/L (range, 0-76 µg/L) and 12 µg/L (range, 0-163 µg/L), respectively. RESULTS: Of the 54 revision THAs, 15 (28%) developed complications. Nine (17%) occurred within 90 days of the revision surgery and 11 (20%) resulted in reoperation. The most common complication was dislocation (12 of 54 [22%]) with recurrent dislocation noted in eight of these 12 patients. All patients with recurrent dislocation continued to dislocate and underwent repeat revision. Patients with dislocation had higher median serum Cr and Co ion levels than those without dislocation (Cr: 24 [range, 11-76] versus 4 [range, 0-70], p = 0.001 [95% confidence interval {CI}, 10-57]; Co: 41 [range, 6-163] versus 8 [range, 0-133], p = 0.016 [95% CI, 6-141]). Three (6%) of the 54 patients underwent repeat surgery for deep space infection. CONCLUSIONS: Complications and reoperations are common after modular head-liner exchange in the setting of a failed MoM THA. Our study likely underestimates the frequency of complications and revisions because the followup period in this report was relatively short. Dislocation is the most common complication and elevated serum metal ion levels may be a predictor of dislocation. These findings are concerning and surgeons should be aware of the high complication risk associated with this procedure. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Radiographic Findings in Patients With Catastrophic Varus Collapse After Total Knee Arthroplasty.

BACKGROUND: Catastrophic varus collapse is an uncommon mechanism of failure in primary total knee arthroplasty (TKA). Varus collapse has been associated with obesity and smaller implant sizes. However, to our knowledge, preoperative radiographic characterization of this cohort has not been performed. Therefore, the following study evaluated preoperative alignment and how this correlates with the degree of eventual varus collapse identified in this patient population prior to revision. METHODS: Utilizing our institutional database, 1106 revision TKAs were performed from 2004 to 2017. Of these, 35 patients were revised secondary to tibial varus collapse. Twenty-seven patients had their primary TKA performed at our institution. Coronal alignment of the knee was recorded from anteroposterior knee radiographs. Medial tibial bone loss was recorded at final follow-up. RESULTS: The average body mass index was 38 kg/m2. Twenty-six of 27 patients had a preoperative varus deformity (4.2° varus) and all were corrected to a valgus coronal alignment immediately postoperatively (5.2° valgus, P = .0001). Twenty-four of 27 patients' coronal alignment after varus collapse was within 2° of their preoperative alignment (5.8° varus). Twenty-five of 27 patients had radiographic medial tibial bone loss prior to varus collapse. CONCLUSION: Tibial varus collapse in an uncommon cause of failure after primary TKA. Preoperative varus deformity, postoperative medial tibial bone loss, and obesity were common findings in this series of patients. Therefore, increased tibial stem lengths should be considered in patients with a preoperative varus deformity, small tibial implant size, and a body mass index ≥35 kg/m2 undergoing primary TKA.

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.

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.