Faculty Bibliography

BACKGROUND:This study compares clinical and functional outcomes between simultaneous hardware removal during total knee arthroplasty (TKA) and staged TKA after prior hardware removal. METHODS:We retrospectively reviewed 155 patients who had prior knee hardware and underwent elective primary TKA between 2012 and 2024 at an urban academic institution. Patients were categorized into "simultaneous" removal during TKA (n = 127) or "staged" TKA after removal (n = 28), and stratified by hardware type (minor/moderate/major). RESULTS:Simultaneous procedures involved significantly less "major hardware," single incisions, and tibial stem extensions than staged procedures (32.3 versus 78.6%, P < 0.001; 81.9 versus 100%, P = 0.007; and 0.8 versus 10.7%, P = 0.019, respectively). Hardware, particularly the major type, was more often retained or partially retained in the simultaneous group (48.0 versus 21.4%, P = 0.008). Reoperation, revision, and infection rates did not significantly differ based on timing or hardware location. Simultaneous patients had smaller 3-month Patient-Reported Outcomes Measurement Information System (PROMIS) Pain Intensity and Interference score reductions (-1.6 versus -9.9, P = 0.006 and +0.4 versus - 7.2, P = 0.007, respectively), but greater 2-year Knee Injury and Osteoarthritis Outcome Score for Joint Replacement improvements (+25.0 versus - 1.1, P = 0.006) compared to staged patients. Simultaneous major hardware removal demonstrated significantly greater 2-year Knee Injury and Osteoarthritis Outcome Score for Joint Replacement and PROMIS Pain Interference improvement (+32.0 versus -5.5, P = 0.001, and -6.2 versus +5.8, P = 0.027, respectively), but smaller 2-week PROMIS Pain Intensity score reduction (+2.2 versus -4.9, P = 0.050) compared to staged procedures. CONCLUSIONS:Simultaneous hardware removal during TKA led to higher retained major hardware rates and fewer single incisions than staged procedures, without increased reoperation or revision risks. Despite higher 3-month pain scores, simultaneous surgery achieved greater 2-year functional improvement, suggesting it offers advantages for select patients.

BACKGROUND:The Centers for Medicare and Medicaid Services now mandates the collection of patient-reported outcome measures (PROMs) before and after total knee arthroplasty (TKA), though their utility in predicting clinical outcomes remains unclear. This study compared the power of preoperative PROMs to predict clinical outcomes after TKA to established indices, including the Charlson Comorbidity Index and the Risk Assessment and Prediction Tool (RAPT). METHODS:We retrospectively reviewed 2,923 patients undergoing elective, primary, unilateral TKA who completed the Knee Injury and Osteoarthritis Outcome Score for Joint Replacement and four Patient-Reported Outcomes Measurement Information System (PROMIS) domains within 90 days preoperatively. Outcomes included same-day discharge (SDD) rate, prolonged length of stay (LOS ≥ 48 hours), nonhome discharge, 90-day readmission, and revision surgery. Predictive utility was assessed using receiver operating characteristic curves (area under the curve [AUC]) and multivariable logistic regressions. RESULTS:The RAPT was the strongest predictor of SDD (AUC = 0.697), extended LOS (AUC = 0.703), and nonhome discharge (AUC = 0.877). The PROMIS Physical Health (AUC = 0.609 for SDD; 0.607 for LOS; 0.696 for discharge) and PROMIS Mental Health (AUC = 0.613; 0.610; 0.655) demonstrated modest predictive value. In adjusted models, higher PROMIS Mental Health was associated with greater odds of SDD (odds ratio (OR) = 1.027, P = 0.003) and lower odds of extended LOS (OR = 0.975, P < 0.001). Higher PROMIS Physical Health was associated with decreased odds of nonhome discharge (OR = 0.935, P = 0.017). The Charlson Comorbidity Index was the strongest predictor of 90-day readmission (AUC = 0.604) and the only significant variable in adjusted models. There were no PROMs that were significant predictors of readmission or revision. CONCLUSIONS:Preoperative PROMs are associated with some clinical outcomes following TKA, but demonstrate limited predictive power compared to established tools like the RAPT score. These findings underscore the need for more robust, outcome-aligned PROMs to improve surgical planning in a value-based care model.

INTRODUCTION/BACKGROUND:Periprosthetic patellar fracture (PPPF) after total knee arthroplasty (TKA) is a rare complication, but can significantly affect patient function and implant survival. This study sought to better identify radiographic and anatomical risk factors for PPPF compared to a propensity-matched cohort. METHODS:We retrospectively queried 22,092 TKAs from January 2011 to December 2024 with patellar resurfacing at a single, urban, academic institution, yielding 44 (0.2%) verified cases of PPPF after TKA. Using propensity score matching on the basis of age, sex, body mass index (BMI), race, and Charlson Comorbidity Index, 44 control TKA patients who had patellar resurfacing without fracture were identified and analyzed using the same methods. RESULTS:The mean time to PPPF was two years after TKA (range, 10 days to 10 years), and 46% were atraumatic. A decreased native lateral patellar tilt (20.0 versus 22.6°, P = 0.039) and thinner native patellar thickness (22.6 versus 24.0 mm, P = 0.018) were associated with increased PPPF risk. Lateralization of the patella during resurfacing also increased risk (P = 0.011), as well as increased patellar component size (P = 0.034). On Receiver Operating Characteristic analysis, thinner native patella thickness was the most predictive of fracture risk (Area Under the Curve = 0.621); however, this result was underpowered, thus an optimal cutoff value could not be meaningfully established. CONCLUSION/CONCLUSIONS:The PPPFs are rare complications following TKA and may occur with or without trauma. Native patellar thickness was inversely correlated with fracture risk, and lateral positioning during resurfacing and increased component size were associated with increased risk. Patients who had PPPFs also demonstrated lesser lateral patellar tilt compared to non-fractured controls. Further investigation with a larger cohort may enable more precise risk factor stratification.

BACKGROUND:Robotic-assisted total knee arthroplasty (RA-TKA) allows for intraoperative component positioning to personalize alignment and gaps. However, traditional trochlear designs not optimized for patellar tracking in kinematic alignment result in femoral internal rotation relative to the surgical transepicondylar axis (TEA). We sought to determine the femoral component alignment's effect on patellar tracking in RA-TKA. METHODS:We retrospectively reviewed 932 RA-TKA cases performed from January 2023 to August 2024 using a computed tomography (CT)-based robotic platform with a single radius femoral component with a 6° trochlear sulcus angle. Femoral rotation was defined as internal (IR) and external (ER) relative to TEA. Femoral coronal alignment was defined as varus (Var) or valgus (Val) relative to the mechanical axis. Patient-reported outcomes were collected at six weeks, three months, and one year postoperatively. Outcomes were analyzed using one-way analyses of variance and Chi-square tests. RESULTS:There were 445 (48%) Var-ER, 242 (26%) Val-ER, 105 (11%) Var-IR, and 141 (15%) Val-IR cases. Mean femoral component rotation (° external) was Var-ER: 2.8° (range, 0.2 to 6.5); Val-ER: 2.4° (range, 0.1 to 5.0); Var-IR: -0.6° (range, -3.4 to 0); and Val-IR: -1.0° (range, -4.2 to 0). There were three patella-related complications, two of which had further reoperations, all of which occurred in the Val-IR cohort (P < 0.001). Knee Injury and Osteoarthritis Outcome for Joint Replacement (KOOS, JR) at six weeks was lowest in the Var-ER cohort (52.3, P < 0.039). Planned femoral IR had no statistically significant impact on three-month and one-year KOOS, JR scores; there were no differences in Patient-Reported Outcomes Measurement Information System (PROMIS) scores at postoperative intervals studied. CONCLUSION/CONCLUSIONS:Planned femoral IR was not associated with statistically significant differences in patient-reported outcomes beyond six weeks postoperatively. However, all patella-related complications occurred in the Val-IR cohort. We caution surgeons against placing excessive combined valgus and IR with femoral implants designed with narrower trochlear sulcus angles.

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.

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.

PURPOSE/OBJECTIVE:To investigate the incidence and risk factors for dressing-induced allergic contact dermatitis (DIACD) following total hip and knee arthroplasty (THA and TKA, respectively) across different dressings and sealants. METHODS:A retrospective review was conducted of patients who underwent primary, elective THA or TKA between 2019 and 2024 with ≥ 90 days of follow-up. Incidences of DIACD were identified by reviewing medical records for "allergy" diagnoses and use of antihistamines or corticosteroids within 30 days postoperatively. Patient characteristics, prior exposure, treatment, dressing type, and allergy history were analyzed. RESULTS:A total of 61 (0.3%) of the 23,396 investigated patients developed a DIACD on average 12.2 ± 7.3 days postoperatively. Overall, 41% had a preoperative allergy (excluding seasonal), and 55.7% were treated with topical or low-dose oral antihistamines and corticosteroids. The majority (41%) of the DIACD involved mesh-adhesive dressings, and a liquid skin adhesive (2-octyl cyanoacrylate) was also used in 41% of cases, often in combination with the primary dressing. Of the 61 DIACD patients, 24 (39.3%) had previously undergone THA or TKA, and nearly half of these (n = 11, 45.8%) had been exposed to the same dressing without prior occurrence of DIACD. DIACD patients were significantly more likely to have undergone TKA (73.8 vs. 58.3%, p = 0.015) and to have never smoked (75.4 vs. 58.4%, p = 0.014). The effect sizes of these findings were negligible (Cramer's V = 0.016 and 0.019, respectively). CONCLUSIONS:The incidence of DIACD following joint arthroplasty is low (0.3%) but remains a frustrating complication, primarily occurring two weeks postoperatively, with mesh-adhesive dressings most frequently implicated. Patients with prior exposure to dressings, those undergoing TKA, and non-smokers are at higher risk. Identifying at-risk patients can guide dressing selection and application.