Faculty Bibliography

Intramedullary stems are often required in patients undergoing revision total knee arthroplasty (rTKA) to achieve stable fixation. Significant bone loss may require the addition of a metal cone to maximize fixation and osteointegration. The purpose of this study was to investigate clinical outcomes in rTKA using different fixation techniques. We conducted a single-institution retrospective review of all patients who received a tibial and femoral stem during rTKA between August 2011 and July 2021. Patients were separated into three cohorts based on fixation construct: press-fit stem with an offset coupler (OS), fully cemented straight (CS) stem, and press-fit straight (PFS) stem. A subanalysis of patients who received tibial cone augmentation was also conducted. A total of 358 patients who underwent rTKA were included in this study, of which 102 (28.5%) had a minimum 2-year follow-up and 25 (7.0%) had a minimum 5-year follow-up. In the primary analysis, 194 patients were included in the OS cohort, 72 in the CS cohort, and 92 in the PFS cohort. When stem type alone was considered, there was no significant difference in rerevision rate (p = 0.431) between cohorts. Subanalysis of patients who received augmentation with a tibial cone demonstrated that OS implants led to significantly higher rates of rerevision compared with the other two stem types (OS: 18.2% vs. CS: 2.1% vs. PFS: 11.1%; p = 0.037). The findings of the present analysis demonstrate that CS and cones in rTKA may provide more reliable long-term outcomes compared with press-fit stems with OS. LEVEL III EVIDENCE:  Retrospective Cohort Study.

INTRODUCTION/BACKGROUND:Round or oval implants are used in patellar resurfacing during total knee arthroplasty (TKA). However, whether component geometry affects clinical outcomes is unclear. This study aimed to determine if one implant shape conferred superior outcomes to the other. METHODS:A retrospective review of primary TKA cases performed from 2016 to 2020 was conducted at an urban, tertiary academic center. 400 consecutive, primary TKAs were included in these analyses. Cases were included if a surgeon used the round design then oval design for fifty consecutive cases. Baseline demographic data and radiographic measurements were assessed. Surgical data, reasons for revision, and patient reported outcome measures were analyzed. Independent samples t- and chi-squared tests were used to compare means and proportions. There were no demographic differences between the cohorts. RESULTS:Post-operative patellar tilt was statistically different between the cohorts. Sixteen patients required revision surgery; however, revision rates did not differ between cohorts. Of the nine round, one button was revised for infection. Of the seven oval, one button was revised for infection and one for loosening. Veterans RAND 12 Physical Component Score at three-months postoperatively was higher for the round cohort, but no differences were observed at one-year. CONCLUSION/CONCLUSIONS:While radiographic patellar tilt was significantly different between the cohorts, there was no clinical correlation in outcomes at three-months or one-year postoperatively. Longer-term follow-up studies are needed to evaluate the implications of patellar component design on outcomes and function. Nevertheless, the current study affirms that both designs are clinically equivalent which should be used to guide clinical decision-making.

AIMS/UNASSIGNED:Revision total knee arthroplasty (rTKA) is a technically challenging and costly procedure. It is well-documented that primary TKA (pTKA) have better survivorship than rTKA; however, we were unable to identify any studies explicitly investigating previous rTKA as a risk factor for failure following rTKA. The purpose of this study is to compare the outcomes following rTKA between patients undergoing index rTKA and those who had been previously revised. METHODS/UNASSIGNED:This retrospective, observational study reviewed patients who underwent unilateral, aseptic rTKA at an academic orthopaedic speciality hospital between June 2011 and April 2020 with > one-year of follow-up. Patients were dichotomized based on whether this was their first revision procedure or not. Patient demographics, surgical factors, postoperative outcomes, and re-revision rates were compared between the groups. RESULTS/UNASSIGNED:= -0.102; p = 0.251). CONCLUSION/UNASSIGNED:Multiply revised TKA had worse outcomes, with higher rates of facility discharge, longer operative times, and greater reoperation and re-revision rates compared to index rTKA.

INTRODUCTION/BACKGROUND:Loosening and migration are common modes of aseptic failure following complex revision total knee arthroplasty (rTKA). Metaphyseal cones allow surgeons to negotiate the loss of femoral and tibial bone stock while obtaining stable bony fixation. This study examines the mid-term functional and radiographic outcomes in patients undergoing rTKA utilizing a novel metaphyseal cone system with stems of variable length and fixation methods. METHODS:This two-center retrospective study examined all patients who underwent rTKA with a novel porous, titanium tibial or femoral cone in combination with a stem of variable length and fixation who had a minimum follow-up of 2-years. Outcome analysis was separated into tibial and femoral cones as well as the stem fixation method (hybrid vs. fully cemented). RESULTS:Overall, 123 patients who received 156 cone implants were included (74 [60.2%] tibial only, 16 [13.0%] femoral only, and 33 [26.8%] simultaneous tibial and femoral) with a mean follow-up of 2.76 ± 0.66 years. At 2-years of follow-up the total cohort demonstrated 94.3% freedom from all-cause re-revisions, 97.6% freedom from aseptic re-revisions, and 99.4% of radiographic cone osteointegration. All-cause revision rates did not differ between stem fixation techniques in both the tibial and femoral cone groups. CONCLUSION/CONCLUSIONS:The use of a novel porous titanium femoral and tibial metaphyseal cones combined with stems in patients with moderate to severe bone defects undergoing complex revision total knee arthroplasty confers excellent results independent of stem fixation technique. LEVEL OF EVIDENCE/METHODS:IV, case series.

Background: The impact of morbid obesity (MO) on outcomes following total knee arthroplasty (TKA) when performed by high-volume (HV) surgeons has not been investigated. This study aimed to assess complication rates and implant survivorship in MO patients operated on by HV surgeons. Methods: Patients undergoing primary, elective TKA between June 2011 and May 2022 with a HV surgeon (top 25% surgeons by the number of primary TKAs per year) were retrospectively reviewed. Patients were stratified by body mass index (BMI) into 3 groups: BMI ≥40 (MO), 30≤ BMI <40 (non-morbidly obese), and BMI <30 (nonobese) and 1:1:1 propensity matched based on baseline characteristics. Of the 12,132 patients evaluated, 1,158 were included in final matched analyses (386 per group). The HV surgeons performed a median of 104 TKAs annually (range, 90-173). Results: The MO patients had significantly longer surgery duration (P = .006) and hospital lengths of stay (P < .001). The 90-day postoperative complications (P = .38) and readmission rates (P = .39) were comparable between groups. Rates of all-cause, septic and aseptic revision were similar between groups at two-year (P = .30, P = .15, and P = .26, respectively) and the latest follow-up (P = .36, P = .52, and P = .38, respectively). Improvement in Knee injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS, JR) scores at 6 months (P = .049) and one year (P = .015) was significantly higher in MO patients. Conclusion: Clinical outcomes and complication rates following TKA by HV surgeons are comparable regardless of obesity status. The MO patients may benefit from referral to experienced surgeons to minimize procedural risks and improve outcomes. Level of Evidence: III.

Cam-post dislocations are a unique complication of total knee arthroplasty (TKA) designs that utilize a cam-post mechanism, representing an extreme form of deep flexion instability. They are rare complications and are poorly defined in the existing literature. The purpose of this case study is to present a series of six cam-post dislocation cases to improve understanding of this complication and its mechanism, presentation, and available treatment options. All patients experienced cam-post dislocations after a deep flexion moment that were identified clinically and confirmed radiographically. Affected implants included both primary and revision components and all utilized a cam-post mecha- nism. Three patients underwent revision surgery whereas the remaining three were treated with closed reduction only. Cam-post dislocations are rare complications of posterior- stabilized TKA that should be understood and recognized by adult reconstruction surgeons. Closed reduction may be achieved with hyperflexion and anterior drawer or with hyperextension, but these patients may ultimately require a revision procedure.

INTRODUCTION/BACKGROUND:Computer-assisted navigation systems (CAS) are increasingly being integrated into total knee arthroplasty (TKA) procedures, but perceptions of associated learning curve and increased operative time continue to curtail uptake. Newer-generation navigational systems aim to streamline integration into surgical workflow to mitigate increases in operative time. Here, we assess the impact of a novel imageless CAS on operative time for TKA. METHODS:A retrospective analysis of prospectively collected data of a cohort of patients undergoing primary unilateral TKA with one of three surgeons between October 2019 and March 2020 was conducted. Consecutive cases using a novel imageless CAS were included in analysis. For each surgeon, average operative time was recorded and compared in sequential five-case cohorts to average operative time for the same procedure performed conventionally using a two-tailed t test. RESULTS:Average conventional operative times were 95.9 ± 15.0, 86.6 ± 13.7, and 116.9 ± 25.1 min for the three surgeons. Initial CAS-assisted operative times increased to 107.0 ± 9.8 (p = 0.07) and 102.4 ± 13.2 (p = 0.06) min for Surgeons 1 and 2 and decreased to 113.2 ± 9.8 min (p = 0.52) for Surgeon 3. Most recent CAS-assisted operative times were 94.8 ± 13.9 (p = 0.88), 88.7 ± 15.3 (p = 0.84), and 104.8 ± 13.2 (p = 0.12) min as compared to pre-CAS. Absolute differences for the most recent navigated procedures ranged from 12.1 min faster to 2.0 min slower. CONCLUSION/CONCLUSIONS:The learning curve for TKA navigation may be as few as 10 cases, and any associated increases in operative time may be transient and non-significant. Moreover, navigation may ultimately speed operative time, perhaps as the result of enhanced intraoperative assessment of alignment.

PURPOSE/OBJECTIVE:Navigated total knee arthroplasty (TKA) improves implant alignment by providing feedback on resection parameters based on femoral and tibial cutting guide positions. However, saw blade thickness, deflection, and cutting guide motion may lead to final bone cuts differing from planned resections, potentially contributing to suboptimal component alignment. We used an imageless navigation device to intraoperatively quantify the magnitude of error between planned and actual resections, hypothesizing final bone cuts will differ from planned alignment. MATERIALS AND METHODS/METHODS:A retrospective study including 60 consecutive patients undergoing primary TKA using a novel imageless navigation device was conducted. Device measurements of resection parameters were obtained via attachment of optical trackers to femoral and tibial cutting guides prior to resection. Following resection, optical trackers were placed directly on the bone cut surface and measurements were recorded. Cutting guide and bone resection measurements of both femoral and tibial varus/valgus, femoral flexion, tibial slope angles, and both femoral and tibial medial and lateral resection depths were compared using a Student's t-test. RESULTS:Femoral cutting guide position differed from the actual cut by an average 0.6 ± 0.5° (p = 0.85) in the varus/valgus angle and 1.0 ± 1.0° (p = 0.003) in the flexion/extension angle. The difference between planned and actual cut measurements for medial and lateral femoral resection depth was 1.1 ± 1.1 mm (p = 0.32) and 1.2 ± 1.0 mm (p = 0.067), respectively. Planned cut measurements based on tibial guide position differed from the actual cut by an average of 0.9 ± 0.8° (p = 0.63) in the varus/valgus angle and 1.1 ± 1.0° (p = 0.95) in slope angle. Measurement of medial and lateral tibial resection depth differed by an average of 0.1 ± 1.8 mm (p = 0.78) and 0.2 ± 2.1 mm (p = 0.85), respectively. CONCLUSIONS:Significant discrepancies between planned and actual femoral bone resection were demonstrated for flexion/extension angle, likely the result of cutting error. Our data highlights the importance of cut verification postresection to confirm planned resections are achieved, and suggests imageless navigation may be a source of feedback that would allow surgeons to intraoperatively adjust resections to achieve optimal implant alignment.

CASE REPORT:A 67-year-old man presented with signs of acute periprosthetic infection after total hip arthroplasty (THA). Surgical debridement, antibiotics, and a head and liner exchange were performed. After showing no improvement, a single-stage revision was conducted. Postoperatively, he developed back pain and lower extremity weakness. Electrodiagnostic studies showed a Guillain-Barré syndrome (GBS) variant. Intravenous immunoglobulin was administered to halt disease progression. After 1 year, he still demonstrated neuromuscular deficits and required a cane for ambulation. CONCLUSION:This case highlights GBS after THA. A high degree of clinical suspicion is essential to prevent misinterpretation as a postsurgical complication. LEVEL OF EVIDENCE:V, case report.

Same-day discharge (SDD) surgery in total hip arthroplasty (THA) has been shown to have similar outcomes to non-SDD THA in select patient populations. Hip resurfacing arthroplasty (HRA) is an alternative to THA for young, active patients, making them ideal candidates for SDD. This study compared the safety and efficacy of non-SDD HRA and SDD HRA for specific postoperative outcomes. An electronic data warehouse query was performed for procedures labeled "hip resurfacing." Data collected included demographics, surgical factors, and quality metrics. Statistical analyses were evaluated using a graphing and statistics software program. Categorical variables were analyzed with chi-square tests and continuous variables with Student's t tests, with P<.05 deemed significant. Sixty-three of 274 total HRAs were enrolled in this SDD HRA protocol. No significant difference was observed between SDD HRA and non-SDD HRA baseline characteristics. On postoperative day 0, 98.41% of SDD HRA recipients were discharged successfully. The SDD HRA recipients had shorter stays, with 1.59% requiring a hospital stay of 2 days or more compared with 56.87% of non-SDD HRA recipients (P<.0001). The non-SDD HRA recipients were found to have shorter surgical times than SDD HRA recipients (104.74 vs 125.51 minutes, P=.01). Rates of infection, periprosthetic fractures, emergency department visits, and hospital readmissions were equivalent (P=.99). Same-day discharge HRA is a safe and effective procedure with similar outcomes to non-SDD HRA regarding infections, fractures, emergency department visits, and readmissions. The major benefit of SDD is a shorter hospital stay that may lead to decreased cost while preserving and enhancing quality of care and patient satisfaction. [Orthopedics. 2020;43(6):e595-e600.].