Faculty Bibliography

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.

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.

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.

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.

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.

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.