Evaluation of an Initial Robotic-Assisted Direct Anterior Approach Cohort Receiving a New Short Metaphyseal Filling Collared Femoral Implant.

BACKGROUND: Shorter, metaphyseal-filling collared stems have become popular with the direct anterior approach (DAA), based on their ease of broaching and insertion through less invasive surgical exposures. To aid with the DAA, robotic-assisted technology provides three-dimensional computed tomography (CT) preoperative planning and intraoperative guidance to accurately assess stem version. With other femoral stems, this has been shown to provide more accurate implant planning and improved patient outcomes. The purpose of this study was to understand femoral stem placement predictability and patient outcomes for a newly designed metaphyseal-filling collared stem system through a DAA in combination with a robotic-assisted system during a single surgeon's initial cases. MATERIALS AND METHODS: A single high-volume surgeon, experienced with robotic-assisted DAA total hip arthroplasty (THA), adopted the use of a metaphyseal-filling collared stem. Intraoperative data and patient outcomes up to six months postoperative were collected prospectively during the surgeon's first 123 cases. Student's t-tests (α=0.05) were used for statistical comparisons. Intraoperative and radiographic assessments were performed for all 123 cases. RESULTS: The estimated version with neck-cut view of the robotic-assisted system was 13.81 ± 3.81°. The final version measurement captured with the robotic-assisted system was 16.56 ± 6.61°. The difference between the estimated version and robotic-assisted measured version was, on average, 2.68 ± 5.7° (p<0.001). The femoral stem sat at the level of the calcar in all but five cases. There were no intraoperative or postoperative periprosthetic fractures. Patients reported significant improvements in reduced Hip dysfunction and Osteoarthritis Outcome Score for Joint Replacement (HOOS-JR), Patient-Reported Outcomes Measurement Information System (PROMIS 10), and Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores throughout their six-month recovery process with no patients reporting a periprosthetic joint infection, fracture, or dislocation. CONCLUSION: The use of a metaphyseal-filling collared stem with robotic-assisted DAA resulted in adequate stem version when assessed visually and with CT scan assessments. Version estimation values were improved upon over visual assessments when using the robotic system that maps out the proximal femur and the improvement was also demonstrated when compared to the prior literature. This may also be related to the stem's collar providing a visual guide during stem placement posterior fill of this triple-tapered stem design. Although further follow up is needed to assess longer-term outcomes, at six months postoperatively, patients had significant improvements in patient-reported outcomes with all patients reporting minimal to no restrictions with their THA.

Decreased Patellar Fractures and Subluxation With Patellar Component Replacement at Stage-One Spacer.

BACKGROUND: Periprosthetic joint infection is a devastating complication of total knee arthroplasty and is often treated with 2-stage revision. We retrospectively assessed whether replacing the patellar component with articulating stage-one spacers was associated with improved outcomes compared to spacers without patellar component replacement. METHODS: A total of 139 patients from a single academic institution were identified who underwent an articulating stage-one revision total knee arthroplasty and had at least 1-year follow-up. Of the 139 patients, 91 underwent patellar component removal without replacement, while 48 had a patellar component replaced at stage-one revision. Patellar fracture and reinfection at any point after stage-one were recorded. Knee range of motion (ROM), patellar thickness, lateral tilt, and lateral displacement were measured at 6-weeks post stage-one. Chi-square, Fisher's exact, and t-tests were utilized for comparisons. There were no significant demographic differences between groups. RESULTS: Patellar component replacement at stage-one revision was associated with fewer patellar fractures (2.1 versus 12.1%, P = .046), less lateral patellar displacement (1.7 versus 16.0 mm, P < .01), and improved pre to postoperative knee ROM 6 weeks after stage-one (+5.9 versus -11.4°, P = .03). There was no difference in reinfections after stage-2 revision for the replaced or unreplaced patellar groups (15.4 versus 15%, P = 1.000). While the mean time between stage-one and stage-2 was not different (5.2 versus 4.5 months, P = .50), at one-year follow-up, significantly more patients in the patellar component replacement group were satisfied and refused stage-2 revision (45.8 versus 3.3%, P < .001). CONCLUSIONS: Replacing the patellar component at stage-one revision is associated with a decreased rate of patellar fracture and lateral patellar subluxation, improved ROM, and possible increased patient satisfaction, as reflected by nearly half of these patients electing to keep their spacer. There was no difference in reinfection rates between the cohorts.

The Empty Ischial Fossa Sign: A Visual Representation of Relative Inadequate Anteversion in the Posteriorly Tilted Pelvis.

Background: Instability is a known complication following total hip arthroplasty (THA) and is influenced by spinopelvic alignment. Radiographic markers have been investigated to optimize the acetabular cup position. This study evaluated if the empty ischial fossa (EIF) sign and the position of the trans-teardrop line were predictive of postoperative instability. Methods: All patients who underwent THA from 2011 to 2018 at a single institution were retrospectively reviewed. Pelvic tilt was measured using a trans-teardrop line compared to the superior aspect of the pubic symphysis on standing anteroposterior pelvis radiographs. Postoperative dislocations were identified through chart review and radiographic review. The EIF sign was determined by the presence of uncovered bone below the posterior inferior edge of the acetabular component at the level of the native ischium and posterior wall on standing postoperative anteroposterior radiographs. Results: One thousand seven hundred fifty patients (952 anterior approach and 798 posterior approach) were included. The EIF sign was present in 458 patients (26.2%) and associated with an increased dislocation rate (3.9% vs 0.9%, P < .0001). Patients with spondylosis/instrumented fusion, and positive EIF sign had a dislocation risk of 5.1% vs 1.3% (P = .001). A postoperative outlet pelvis was not significant for increased dislocation risk (odds ratio 2.16, P = .058). Patients with combined spondylosis/fusion, posterior approach, outlet pelvis, and EIF sign had a dislocation rate of 14.5%. Conclusions: The EIF sign was an independent risk factor for postoperative instability and may represent failure to account for pelvic tilt. Avoidance of the EIF sign during cup positioning may help reduce dislocations following THA.

Metallosis and Corrosion Associated With Revision Total Knee Arthroplasties With Metaphyseal Sleeves.

Metallosis and corrosion have been associated with metal-on-metal and modular total hip arthroplasty but are rarely described in the setting of primary or revision total knee arthroplasty (TKA). In this series, we report on cases of metallosis due to mechanically assisted crevice corrosion at modular junctions of machined trunnion-bore tapers in a revision TKA system with metaphyseal sleeves. The unique design of metal modular junctions used in sleeve-based revision TKA, along with potential patient and surgical factors, may predispose these designs to fretting, corrosion, and adverse reaction to metal debris. We now consider metallosis and corrosion in the workup of painful or failed revision TKAs with sleeves. Future studies that investigate the incidence of this phenomenon may be warranted.

A Novel Method to Calculate Functional Pelvic Tilt Using a Standing Anteroposterior Pelvis Radiograph.

Background: Functional patient-specific acetabular component positioning is important in total hip arthroplasty. We preoperatively evaluate the pelvic tilt (PT) on standing anteroposterior (AP) pelvis radiographs using a novel measurement and then recreate this intraoperatively using imaging. The purpose of this study was to determine if there is a linear correlation between this novel measurement and the actual PT. Methods: A retrospective study of 200 patients was performed, measuring PT on standing lateral radiographs as the angle between the anterior superior iliac spines and the pubic symphysis. On the AP pelvis radiographs, the trans-teardrop (TT) line was drawn between the teardrops. The vertical distance between the TT line and the top of the pubic symphysis (TTPS) was then measured. A ratio was made between the lengths of both lines to account for the overall size of the pelvis (TTPS/TT). Linear regression analysis was then performed between PT and TTPS/TT. Results: There was a strong linear correlation between the TTPS/TT ratio on AP pelvis radiographs and PT on lateral radiographs (r = 0.785, r2 = 0.616, P < .001). On subanalysis of the female cohort, the correlation became even stronger (r = 0.864, r2 = 0.747, P < .001). Using regression analysis, a linear equation was created (PT = 97.32 [TTPS/TT] - 5.51), to calculate the PT using the TTPS/TT ratio. Conclusions: There is a strong linear correlation between the TTPS/TT ratio and PT. Using this information, a surgeon can reliably use the distance between the TT line and the superior pubic symphysis on an AP radiograph to recreate the patient's functional PT intraoperatively, allowing for a more accurate patient-specific placement of the acetabular component.

A Multilingual Chatbot Can Effectively Engage Arthroplasty Patients Who Have Limited English Proficiency.

BACKGROUND: In the United States, English language proficiency is widely accepted as a key social determinant of health. For patients with limited English proficiency (LEP), language barriers can make the delivery of perioperative instructions challenging. The purpose of this study was to evaluate whether a multilingual chatbot could effectively engage LEP patients and improve their outcome after total joint arthroplasty (TJA). METHODS: We identified 1,282 TJA patients (705 knees, 577 hips) who enrolled in a short message service (SMS) chatbot from 2020-2022. Forty-seven patients enrolled in the chatbot received their messages in a language other than English. A historical control of 68 LEP patients not enrolled in the chatbot was identified. Chi-squared, Fisher's exact test, and t-tests were performed to measure the effect that conversational engagement had on emergency department (ED) visits, hospital readmissions, and reoperations. RESULTS: There was no difference in the conversational engagement between LEP patients and those with English as their primary language (EPL) (12.3 versus 12.2 text responses, P = .959). The LEP cohort who enrolled in the chatbot had fewer readmissions (0% versus 8.3%, P = .013) and a near significant reduction in ED visits (0.9% versus 8.0%, P = .085) compared to those not enrolled. There was no difference in reoperations between the 2 cohorts. CONCLUSION: LEP and EPL patients engaged equally with the multilingual chatbot. LEP patients who enrolled in the chatbot had fewer readmissions and a near significant reduction in ED visits. Multilingual platforms such as this chatbot may provide more equitable care to our frequently encountered LEP patients.

Displaced Versus Nondisplaced Femoral Neck Fractures: Is Arthroplasty the Answer for Both?

BACKGROUND: Traditionally, nondisplaced geriatric femoral neck fractures (FNFs) have undergone operative fixation, while displaced geriatric FNFs have undergone hip arthroplasty. The purpose of this study was to evaluate differences between outcomes in patients with nondisplaced (Garden I and II) fractures and displaced (Garden III and IV) fractures that were treated with arthroplasty. METHODS: This was a retrospective review of patients who had a minimum of 1 year follow-up from nine academic medical centers who underwent arthroplasty for FNFs between 2010 and 2020. Chi-square, Fisher's Exact, and t-tests were used to compare demographics and outcomes between patients who had a displaced fracture and those who had a nondisplaced fracture. We included 1,620 patients, with 131 in the nondisplaced cohort and 1,497 in the displaced cohort. The mean follow-up in the study was 26.4 months. Both groups were similar in terms of demographic variables. RESULTS: At 1-year follow-up, the overall reoperation rate was 7% and was not different between patients who had nondisplaced compared to displaced FNFs who underwent arthroplasty. Heterotopic ossification (HO) was significantly higher in displaced (23.6%) versus nondisplaced fractures (11.7%) (P = .0021). Operative times and blood loss were higher in nondisplaced than displaced fractures that underwent arthroplasty. CONCLUSION: Hip arthroplasty is an excellent treatment option for nondisplaced and displaced geriatric FNFs with relatively low and similar reoperation rates at 1 year. Compared to previously published reoperation rates of internal fixation of nondisplaced FNFs, hip arthroplasty is a reasonable treatment option for nondisplaced FNFs to potentially decrease reoperations in a frail patient population.

Update on the electrolytic IVC model for pre-clinical studies of venous thrombosis.

BACKGROUND: The electrolytic inferior vena cava model (EIM) is a murine venous thrombosis (VT) model that produces a non-occlusive thrombus. The thrombus forms in the direction of blood flow, as observed in patients. The EIM is valuable for investigations of therapeutics due to the presence of continuous blood flow. However, the equipment used to induce thrombosis in the original model description was expensive and has since been discontinued. Further, the fibrinolytic system had not been previously studied in the EIM. OBJECTIVES: We aimed to provide an equipment alternative. Additionally, we further characterized the model through mapping the current and time dependency of thrombus resolution dynamics, and investigated the fibrinolytic system from acute to chronic VT. RESULTS: A voltage to current converter powered by a direct current power supply was constructed and validated, providing an added benefit of significantly reducing costs. The current and time dependency of thrombus volume dynamics was assessed by MRI, demonstrating the flexibility of the EIM to investigate both pro-thrombotic and anti-thrombotic conditions. Additionally, the fibrinolytic system was characterized in EIM. Centripetal distribution of plasminogen was observed over time, with peak staining at day 6 post thrombus induction. Both active circulating plasminogen activator inhibitor-1 (PAI-1) and vein wall gene expression of PAI-1 peaked at day 2, coinciding with a relative decrease in tissue plasminogen activator and urokinase plasminogen activator. CONCLUSIONS: The EIM is a valuable model of VT that can now be performed at low cost and may be beneficial in investigations of the fibrinolytic system.