Faculty Bibliography

Background Metal hypersensitivity in patients undergoing total knee arthroplasty (TKA) remains a poorly defined clinical entity. This study aimed to characterize the clinical burden of metal hypersensitivity in a national database. The primary objective was to evaluate trends in metal hypersensitivity diagnosis in the general and TKA populations, as well as the TKA revision rate in patients with and without metal hypersensitivity. Secondary objectives were to identify trends in the release of "metal-sensitive" joint replacement alternatives. Methods A retrospective analysis was conducted using the Merative MarketScan Commercial and Medicare Supplemental databases from January 2018 to December 2023. Patients with a diagnosis of metal hypersensitivity were identified using International Classification of Diseases 10th Edition (ICD-10) codes. Annual incidence was calculated for the general population and for patients undergoing TKA. TKA revision rates were calculated for patients with and without metal hypersensitivity. Secondary analyses assessed the incidence of novel TKA implants that are specifically advertised as "metal sensitive". Results The overall incidence of metal hypersensitivity in the general database population ranged from 0.019% to 0.025%. Patients undergoing TKA demonstrated significantly higher rates of metal allergy diagnosis (p<0.001, annually), with the overall incidence ranging from 0.133% to 0.165%. Non-significant downward trends in the incidence of metal hypersensitivity were noted in both the general and TKA populations. Patients with metal hypersensitivity had TKA revisions at a rate that was significantly higher than those who did not (14.03% vs. 3.15%). (p < 0.001). Patients with a diagnosis of metal allergy represented 0.68% of all revision cases. Seven novel orthopedic implants with explicit "metal sensitive" marketing were released between 2018 - 2025. Conclusion This national database study demonstrates low and stable rates of metal hypersensitivity among both the general and TKA patients. There was no change in the incidence of metal hypersensitivity in either population over time. Patients with metal hypersensitivity represented less than 1% of TKA revisions. These findings challenge the value of medical device development for niche markets.

For femoral reconstruction in revision total hip arthroplasty (rTHA), cementless, diaphyseal engaging femoral components are the most commonly-used implants. At present, there are no reviews that directly compare the design features of these implants. We performed a manual review of the designs of commercially available diaphyseal engaging femoral stems. We compiled and compared the design features of these implants. Clinical outcomes of modular and monoblock stems were also compared. We identified five modular and four monoblock stems in the manual review of commercial companies manufacturing these stems. Distal stem taper varied from 2° to 3.5°, and the number of splines varied from 8 to 16. The stems varied in their stem lengths, offsets, and surface finish. Although there are no clinically significant differences in the restoration of leg length between monoblock compared to modular stems. The modular stems appear to perform slightly better with respect to subsidence and restoration of leg length. A source of concern for modular stems are mechanical implant failures that occur almost exclusively at modular junctions. Current evidence does not support any difference in dislocation rate, intraoperative or postoperative fracture, aseptic loosening, re-revision rates, or clinical outcomes between monoblock and modular stems. With the knowledge of the distinct features of implants, surgeons must make choices associated with specific design characteristics that could be pivotal to the success of the operation. Our understanding of design differences will help us minimize chances of failure and choose patient-specific implants that will lead to a high rate of success.

For femoral reconstruction in revision total hip arthroplasty (rTHA), cementless, diaphyseal engaging femoral components are the most commonly-used implants. At present, there are no reviews that directly compare the design features of these implants. We performed a manual review of the designs of commercially available diaphyseal engaging femoral stems. We compiled and compared the design features of these implants. Clinical outcomes of modular and monoblock stems were also compared. We identified five modular and four monoblock stems in the manual review of commercial companies manufacturing these stems. Distal stem taper varied from 2° to 3.5°, and the number of splines varied from 8 to 16. The stems varied in their stem lengths, offsets, and surface finish. Although there are no clinically significant differences in the restoration of leg length between monoblock compared to modular stems. The modular stems appear to perform slightly better with respect to subsidence and restoration of leg length. A source of concern for modular stems are mechanical implant failures that occur almost exclusively at modular junctions. Current evidence does not support any difference in dislocation rate, intraoperative or postoperative fracture, aseptic loosening, re-revision rates, or clinical outcomes between monoblock and modular stems. With the knowledge of the distinct features of implants, surgeons must make choices associated with specific design characteristics that could be pivotal to the success of the operation. Our understanding of design differences will help us minimize chances of failure and choose patient-specific implants that will lead to a high rate of success.

BACKGROUND:Tranexamic acid (TXA) has reduced, but not eliminated, blood transfusions surrounding total knee arthroplasty (TKA). Identifying risk factors for transfusion remains important for risk reduction and type and screen (T and S) optimization. METHODS:We retrospectively reviewed 7,254 patients who underwent primary, unilateral TKA and 307 patients who underwent primary bilateral TKA between January 2014 and January 2023, who received perioperative TXA and had preoperative hemoglobin (Hgb) values. We compared demographics, baseline Hgb levels, and surgical details between patients who were and were not transfused. Data were analyzed utilizing multivariate regressions and receiver operating characteristic (ROC) analyses. A total of 172 unilateral TKA patients (2.4%) received perioperative transfusions, with 170 (2.3%) receiving postoperative transfusions and two (0.03%) receiving intraoperative transfusions. There were 26 bilateral TKA patients (8.5%) who received postoperative transfusions with no documented intraoperative transfusions. RESULTS:For unilateral TKA, the risk of transfusion demonstrated an inverse correlation with preoperative Hgb levels, a bimodal association with body mass index (BMI), and a direct correlation with American Society of Anesthesiologists (ASA) class and estimated blood loss (EBL) on multivariate testing. The ROC analyses demonstrated an optimal Hgb cutoff of 12.1 g/dL for predicting transfusion. The transfusion rate below Hgb of 12.1 g/dL was 6.6%, compared to a rate of 1.4% above this Hgb threshold. Below Hgb of 11 g/dL, the transfusion rate was 11.1%, while for Hgb between 11 and 12 g/dL, the transfusion rate was 4.6%. CONCLUSION/CONCLUSIONS:Transfusion is rare in unilateral TKA when TXA is used and preoperative Hgb is ≥ 12.1 g/dL, challenging universal T and S. Patients who have Hgb less than 11.0 g/dL and bilateral TKA patients remain at higher risk. Risk factors such as Hgb between 11 and 12 g/dL, BMI, ASA and EBL may predict transfusion risk and need for T and S.

BACKGROUND:Tranexamic acid (TXA) has reduced, but not eliminated, blood transfusions surrounding total knee arthroplasty (TKA). Identifying risk factors for transfusion remains important for risk reduction and type and screen (T and S) optimization. METHODS:We retrospectively reviewed 7,254 patients who underwent primary, unilateral TKA and 307 patients who underwent primary bilateral TKA between January 2014 and January 2023, who received perioperative TXA and had preoperative hemoglobin (Hgb) values. We compared demographics, baseline Hgb levels, and surgical details between patients who were and were not transfused. Data were analyzed utilizing multivariate regressions and receiver operating characteristic (ROC) analyses. A total of 172 unilateral TKA patients (2.4%) received perioperative transfusions, with 170 (2.3%) receiving postoperative transfusions and two (0.03%) receiving intraoperative transfusions. There were 26 bilateral TKA patients (8.5%) who received postoperative transfusions with no documented intraoperative transfusions. RESULTS:For unilateral TKA, the risk of transfusion demonstrated an inverse correlation with preoperative Hgb levels, a bimodal association with body mass index (BMI), and a direct correlation with American Society of Anesthesiologists (ASA) class and estimated blood loss (EBL) on multivariate testing. The ROC analyses demonstrated an optimal Hgb cutoff of 12.1 g/dL for predicting transfusion. The transfusion rate below Hgb of 12.1 g/dL was 6.6%, compared to a rate of 1.4% above this Hgb threshold. Below Hgb of 11 g/dL, the transfusion rate was 11.1%, while for Hgb between 11 and 12 g/dL, the transfusion rate was 4.6%. CONCLUSION/CONCLUSIONS:Transfusion is rare in unilateral TKA when TXA is used and preoperative Hgb is ≥ 12.1 g/dL, challenging universal T and S. Patients who have Hgb less than 11.0 g/dL and bilateral TKA patients remain at higher risk. Risk factors such as Hgb between 11 and 12 g/dL, BMI, ASA and EBL may predict transfusion risk and need for T and S.

Arthrofibrosis can be a major source of dissatisfaction for patients undergoing total knee arthroplasty (TKA). Manipulation under anesthesia (MUA) may be offered to improve motion in selected cases. Advancements in computer-navigated and robotic-assisted technology have been championed to improve component positioning with fewer soft tissue releases. We sought to investigate whether these technologies impact MUA rates. An institutional retrospective review was conducted on 18,815 patients who underwent a primary, elective, unilateral TKA between January 2010 and December 2022. Patients were stratified into conventional (n = 12,659), computer-navigated (n = 4,071), or robotic-assisted TKA (n = 2,085) cohorts. Patient demographics and implant data, including mode of fixation and level of constraint (cruciate-retaining [CR] vs. posterior-stabilized) were collected. MUA rates were the primary outcome. Data were analyzed using analysis of variance with Tukey post hoc testing and multivariate logistic regression analysis. We report a 1.7% overall MUA rate, with a rate of 1.6% for conventional and 1.5% for navigated TKA, which were significantly lower than robotic-assisted TKA at 3.2% (p < 0.001). However, on multivariate analysis, there was no difference in MUA rates for navigated and robotic-assisted when compared with conventional techniques. Cementless and hybrid fixation and CR implant designs were higher with robotic-assisted compared with conventional and navigated TKA. Multivariate regression revealed that TKA with fully cementless (odds ratio [OR]: 1.80 [95% confidence interval [CI]: 1.16-2.78]; p = 0.008) or hybrid fixation (OR: 2.92 [95% CI: 1.77-4.81]; p < 0.001) increased the risk for future MUA. Constraint also significantly influenced MUA rates, with CR designs yielding higher MUA rates (OR: 1.51 [95% CI: 1.16-1.96]; p = 0.002). When controlling for confounding factors, navigated and robotic-assisted TKA generated comparable odds for MUA when compared with conventional techniques. However, robotic-assisted TKA were more likely to utilize cementless or hybrid fixation and CR implant constraint, each of which were independently associated with increased odds of MUA. These operative factors should be considered when risk-stratifying and counseling patients on the likelihood of MUA. LEVEL OF EVIDENCE:  III.

AIMS/UNASSIGNED:Total hip arthroplasty (THA) in the setting of proximal femoral defects and poor bone stock often necessitates distal fixation using specialized implants, such as monolithic tapered, fluted titanium stems (TFTSs), to ensure adequate stability. This study evaluates the mid-term outcomes of TFTS in both primary and revision THA. METHODS/UNASSIGNED:This was a multi-institutional retrospective review of patients who received monolithic TFTS between July 2016 and June 2020 during either complex primary THA or revision THA. Outcomes included pre-, intra- and postoperative characteristics, as well as five-year all-cause, septic and aseptic revisions, and Hip disability and Osteoarthritis Outcome Score for Joint Replacement (HOOS, JR) at different postoperative timepoints. RESULTS/UNASSIGNED:A total of 115 patients with a mean follow-up of 6.3 years (SD 1.2) were included. Femoral component survivorship free from aseptic revisions was 99.1% (95% CI 97.3 to 100) at 5.1 years after TFTS. Aseptic revision occurred in a single patient (0.9%) due to periprosthetic acetabular fracture that necessitated femoral component removal for exposure 60.6 months following TFTS. Survivorship from septic revisions was 93.2% (95% CI 91.5 to 99.9) at 5.3 years. Septic revisions included debridement, irrigation and exchange of modular components (n = 3, 2.6%), and two-stage revision arthroplasties (n = 4, 3.5%) at a mean of 27.7 months after surgery (1.5 to 63.9). All-cause survivorship from any revision was 92.4% (95% CI 90.5 to 100) at 5.3 years after TFTS. HOOS, JR scores improved from preoperative to five-year follow-up (46.1 (SD 20.8) to 83.8 (SD 19.0), respectively). CONCLUSION/UNASSIGNED:The TFTS demonstrates excellent mid-term survivorship (99.1% at five years) and significant clinical improvement in complex primary and revision THA. These outcomes suggest that the TFTS can be considered a valuable option in this challenging patient population.

BACKGROUND:Despite theoretical risks of fatigue wear, there is little empirical evidence correlating postoperative impact level from physical activity with failure rates following total hip and knee arthroplasty (THA and TKA). This study aimed to assess the relationship between the impact level from self-reported sports and physical activity participation and revision rates following primary arthroplasty. METHODS:A survey was conducted on recreational sports participation among primary elective THA and TKA patients from an urban, academic health system between June 1, 2011, and January 31, 2022. A total of 1,622 THA and 1,388 TKA respondents were included in the study. The survey was administered cross-sectionally at various time points, with a minimum follow-up of at least one year required for inclusion (THA, 5.3 years; TKA, 4.8 years postoperation on average). Patients were divided into four cohorts based on participation and intensity of the sport: no sports, low-impact sports, intermediate-impact sports, and high-impact sports. Descriptive comparisons were made to evaluate revision rates and mean time to follow-up among these groups in THA and TKA patients. The Kaplan-Meier method was utilized to assess 10-year implant survivability. RESULTS:Healthier and younger patients who underwent THA or TKA were significantly more likely to participate in intermediate- to high-impact sports and were found to have noninferior revision rates than those who engaged in no sports or low-impact sports: THA (2.9 [no sports] versus 1.9 [low impact] versus 1.6% [intermediate/high impact]), TKA (3.0 versus 1.6 versus 0.0%). When analyzing aseptic versus septic revisions separately, no notable patterns or differences were observed. CONCLUSIONS:At a mean 5-year follow-up, healthier and younger patients who participated in intermediate- and high-impact physical activities had noninferior revision rates as than patients who were less active. These findings offer guidance for clinicians when advising patients on the safe resumption of sports activities following total joint arthroplasty.

BACKGROUND:This study examined whether the timing of total hip or knee arthroplasty (TJA) relative to elective hand surgery (HS) is associated with perioperative TJA outcomes, as both are among the most common orthopaedic procedures in the United States. METHODS:A retrospective cohort study was conducted of patients who underwent elective HS and TJA between 2011 and 2024. Patients were grouped by surgical order: HS first (HSF, n = 645) and TJA first (TJAF, n = 785). Differences between HSF and TJAF were assessed. Multivariable logistic regressions, Cox proportional hazards regressions, and linear regressions were used to adjust for patient demographics and comorbidities. The HSF patients were older (67.1 versus 64.3 years, P < 0.001), more prone to be discharged home (90.7 versus 83.8%, P < 0.001), and had a shorter length of stay (45.6 versus 60.4 hours, P < 0.001) compared to TJAF patients. RESULTS:Surgical order showed no association with 90-day emergency department visits and readmissions. Multivariable Cox regressions revealed that HSF was associated with a significantly higher hazard of aseptic revision (hazard risk (HR) = 2.65, P = 0.012). Functional TJA outcomes did not differ (P > 0.05) between groups. Although both groups improved in Patient-Reported Outcomes Measurements Information System (PROMIS) Pain Intensity and Pain Interference scores after TJA, HSF patients showed significantly less improvement in Pain Intensity at all timepoints (P < 0.05). Surgical order was not associated with improvement in Knee Injury and Osteoarthritis Outcome Score for Joint Replacement, Hip Injury and Osteoarthritis Outcome Score for Joint Replacement, or PROMIS Pain Interference scores. CONCLUSIONS:The timing of these elective surgeries is associated with TJA outcomes. While HSF is linked to a higher adjusted risk of aseptic revision, it is also independently associated with less adjusted improvement in PROMIS Pain Intensity. These findings suggest that although surgical order impacts specific recovery metrics, a patient's comorbidities may be the primary driver of complications.