Faculty Bibliography

INTRODUCTION/UNASSIGNED:Radiolucent lines occasionally develop around the proximal aspect of fully hydroxyapatite (HA)-coated tapered femoral stems after total hip arthroplasty (THA). It was hypothesised that distal wedging of stems may predispose to proximal radiolucent line formation, which may negatively impact clinical outcome. METHODS/UNASSIGNED: 244). Radiographic measures of proximal femoral morphology and femoral canal fill at the middle and distal thirds of the stem were analysed for association with the presence of proximal radiolucent lines. Linear regression was used to explore any association between radiolucent lines and patient reported outcome measures (PROMs), available in 61% of patients. RESULTS/UNASSIGNED: 0.001). No correlation was observed between pain or PROMs and the presence of proximal radiolucent lines. DISCUSSION/UNASSIGNED:We observed an unexpectedly high incidence of proximal femoral radiolucent lines about collarless fully HA coated stems. Distal-only implant wedging in Dorr A bone may compromise proximal fixation. Although this finding did not correlate with short-term outcomes, the long-term clinical impact requires further study.

INTRODUCTION/BACKGROUND:Comparison between fully hydroxyapatite (HA)-coated stems with differing geometry are lacking in the total hip arthroplasty (THA) literature. This study aimed to compare femoral canal fill, radiolucency formation, and 2-year implant survivorship between two commonly used, HA-coated stems. METHODS:All primary THAs performed with two fully HA-coated stems (Polar stem, Smith&Nephew, Memphis, TN and Corail stem, DePuy-Synthes, Warsaw, IN) with a minimum 2-year radiographic follow-up were identified. Radiographic measures of proximal femoral morphology based on the Dorr classification and femoral canal fill were analyzed. Radiolucent lines were identified by Gruen zone. Perioperative characteristics and 2-year survivorship were compared between stem types. RESULTS:A total of 233 patients were identified with 132 (56.7%) receiving the Polar stem (P) and 101 (43.3%) receiving the Corail stem (C). No differences were observed with respect to proximal femoral morphology. Femoral stem canal fill at the middle third of the stem was greater for P stem patients than for C stem patients (P stem; 0.80 ± 0.08 vs. C stem; 0.77 ± 0.08, p = 0.002), while femoral stem canal fill at the distal third of the stem and presence of subsidence were comparable between groups. A total of six and nine radiolucencies were observed in P stem and C stem patients, respectively. Revision rate at 2-year (P stem; 1.5% vs C stem; 0.0%, p = 0.51) and latest follow-up (P stem; 1.5% vs C stem; 1.0%, p = 0.72) did not differ between groups. CONCLUSION/CONCLUSIONS:Greater canal fill at the middle third of the stem was observed for the P stem compared to the C stem, however, both stems demonstrated robust and comparable freedom from revision at 2-year and latest follow-up, with low incidences of radiolucent line formation. Mid-term clinical and radiographic outcomes for these commonly used, fully HA-coated stems remain equally promising in THA despite variations in canal fill.

INTRODUCTION/BACKGROUND:Preoperative planning of total hip arthroplasty (THA) using two-dimensional low-dose (2DLD) full-body imaging has gained popularity in recent years. The low-dose imaging system is said to produce a calibrated image with constant 1:1 magnification. However, the planning software used in conjunction with those images may introduce variations in the degree of magnification in 2DLD imaging, and this has not yet been investigated. The purpose of the present study was to quantify any variation in 2DLD image to assess the need for image calibration when using conventional planning software. METHODS:Postoperative 2DLD images from 137 patients were retrospectively evaluated. Only patients who underwent THA for primary osteoarthritis were included in the study cohort. The femoral head diameter was measured by two independent observers using both Orthoview™ and TraumaCad™ planning software programs. Actual sizes of the femoral head implants were extracted from surgical reports to calculate image magnification. Magnification measurement reliability was calculated with the intra-class correlation coefficient (ICC) index. RESULTS:Image magnification varied among cases (mean 133%, range 129-135%). There was no statistical difference in mean image magnification among the various implant sizes (p = 0.8). Mean observer and inter-observer reliability was rated excellent. CONCLUSION/CONCLUSIONS:THA planning with 2DLD imaging is subject to variation in magnification as analyzed with conventional planning software in this series. This finding is of paramount importance for surgeons using 2DLD imaging in preparation for THA since errors in magnification could affect the accuracy of preoperative planning and ultimately the clinical outcome.

INTRODUCTION/BACKGROUND:Selective use of dual mobility (DM) implants in total hip arthroplasty (THA) patients at high dislocation risk has been proposed. However, evidence-based utilization thresholds have not been defined. We explored whether surgeon-specific rates of DM utilization correlate with rates of readmission and reoperation for dislocation. METHODS:We retrospectively reviewed 14,818 primary THA procedures performed at a single institution between 2011 and 2021, including 14,310 FB and 508 DM implant constructs. Outcomes including 90-day readmissions and reoperations were compared between patients who had fixed-bearing (FB) and DM implants. Cases were then stratified into three groups based on the attending surgeon's rate of DM utilization (≤1, 1 to 10, or >10%) and outcomes were compared. RESULTS:There were no differences in 90-day outcomes between FB and DM implant groups. Surgeon frequency of DM utilization ranged from 0 to 43%. There were 48 surgeons (73%) who used DM in ≤ 1% of cases, 11 (17%) in 1 to 10% of cases, and 7 (10%) in >10% of cases. The 90-day rates of readmission (7.3 vs 7.6 vs 7.2%, P=0.7) and reoperation (3.4 vs 3.9 vs 3.8%, P=0.3), as well as readmission for instability (0.5 vs 0.6 vs 0.8%, P=0.2) and reoperation for instability (0.5 vs 0.5 vs 0.8%, P=0.6), did not statistically differ between cohorts. CONCLUSION/CONCLUSIONS:Selective DM utilization did not reduce 90-day readmissions or reoperations following primary THA. Other dislocation-mitigation strategies (i.e., surgical approach, computer navigation, robotic assistance, and large diameter fixed-bearings) may have masked any benefits of selective DM use.

INTRODUCTION:A "morphometric" tapered femoral stem with size-specific medial curvatures and proportional neck lengths was introduced, attempting to improve fixation and biomechanics in cementless total hip arthroplasty (THA) across a range of femoral sizes and morphotypes. We investigated whether this design reduced complications and better restored anatomy (e.g., limb length and offset) compared to a traditional tapered stem with consistent neck lengths across sizes. MATERIALS AND METHODS:We reviewed 389 THAs (340 patients) performed using either of two cementless femoral implants. Records were reviewed for demographics, surgical details, complications, and reoperations. Radiographs were examined for subsidence, biologic fixation, leg lengths, offset, and proximal femoral morphology. RESULTS:The intraoperative fracture rate was lower with this morphometric stem compared to this traditional stem (0 vs. 3.4%), as was the incidence of postoperative subsidence ≥3mm (4.7 vs. 19.2%). With the numbers available, no differences were identified regarding rates of reoperation for periprosthetic femur fracture (0 vs. 1.0%) and femoral fixation failure without fracture (1.1 vs. 0%), or all-cause reoperations (2.7 vs. 2.4%). Limb length and offset restoration were similar with the two implants, but the shortest available femoral head was used less frequently with this morphometric stem compared to this traditional stem (22 vs. 54%). CONCLUSIONS:This morphometric stem was associated with decreased rates of intraoperative fracture and postoperative subsidence, along with decreased use of the shortest available head. Nevertheless, both implants demonstrated clinical success, allowing reconstruction of limb length and offset with low rates of femoral fixation failure.

INTRODUCTION/BACKGROUND:The term "spinopelvic mobility" is most often applied to motion within the spinopelvic segment. It has also been used to describe changes in pelvic tilt between various functional positions, which is influenced by motion at the hip, knee, ankle and spinopelvic segment. In the interest of establishing a consistent language for spinopelvic mobility, we sought to clarify and simplify its definition to create consensus, improve communication, and increase consistency with research into the hip-spine relationship. METHODS:A literature search was performed using the Medline (PubMed) library to identify all existing articles pertaining to spinopelvic mobility. We reported on the varying definitions of spinopelvic mobility including how different radiographic imaging techniques are used to define mobility. RESULTS:The search term "spinopelvic mobility" returned a total of 72 articles. The frequency and context for the varying definitions of mobility were reported. 41 papers used standing and upright relaxed-seated radiographs without the use of extreme positioning, and 17 papers discussed the use of extreme positioning to define spinopelvic mobility. DISCUSSION/CONCLUSIONS:Our review suggests that the definitions of spinopelvic mobility is not consistent in the majority of published literature. We suggest descriptions of spinopelvic mobility independently consider spinal motion, hip motion, and pelvic position, while recognizing and describing their interdependence.

BACKGROUND:The knee-hip-spine syndrome has been well elucidated in the literature in recent years. The aim of this study was to evaluate the effect of total knee arthroplasty (TKA) on spinopelvic sagittal alignment in patients with and without pre-TKA lumber spinal fusion. METHODS:This is a retrospective cohort study of 113 patients who underwent TKA for primary osteoarthritis. Patients were stratified into the following three groups: (1) patients who had pre-TKA spinal fusion (SF, n = 19), (2) patients who had no spinal fusion but experienced pre-TKA flexion contracture (FC, n = 20), and (3) patients without flexion contracture or spinal fusion before TKA (no SF/FC, n = 74). Spinopelvic sagittal alignment parameters, including pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), thoracic kyphosis (TK), and plumb line-sacrum distance (SVA) were measured preoperatively and 3 months postoperatively on lateral standing full-body low-dose images. RESULTS:TKA resulted in significant pre- to postoperative changes in pelvic tilt (average ∆ PT = - 8.6°, p = 0.018) and sacral slope (average ∆ SS = 8.6°, p = 0.037) in the spinal fusion (SF) group. Non-significant changes in spinopelvic sagittal alignment parameters (PT, SS, LL, TK, SVA) were noted postoperatively in all patients in the FC and the no SF/FC groups. CONCLUSIONS:TKA can lead to meaningful changes in spinopelvic alignment in patients with prior lumbar fusion compared to those without spinal fusion. Patients with spinal fusion who are candidates for both hip and knee replacements should consider undergoing TKA first since changes in spinopelvic sagittal alignment can increase the risk of future complications. LEVEL III EVIDENCE/METHODS:Retrospective Cohort Study.

BACKGROUND:The growing variety of total hip arthroplasty implants necessitates a standardized, simple, and brand-neutral language to precisely classify femoral components. Although previous classifications have been useful, they need updating to include stems that have current surface treatment technologies, modularity, collar features, and other geometric characteristics. METHODS:To accomplish this, we propose a new classification system for stems based on 3 distinguishing stem features: (1) geometry, (2) location of modularity, and (3) length. RESULTS:Our system allows for the easy classification of all currently used stem types. CONCLUSIONS:One goal of this endeavor is to improve clinical record keeping to facilitate study comparisons as well as literature reviews.

BACKGROUND:Indications for surgery may impact resource utilization in aseptic revision total knee arthroplasty (rTKA), and understanding these relationships would facilitate risk-stratification preoperatively. The purpose of this study was to investigate the impact of rTKA indications on readmission, reoperation, length of stay (LOS), and cost. METHODS:We reviewed all 962 patients who underwent aseptic rTKA at an academic orthopedic specialty hospital between June 2011-April 2020 with at least 90 days of follow-up. Patients were categorized based on their indication for aseptic rTKA as listed in the operative report. Demographics, surgical factors, LOS, readmission, reoperation and cost were compared between cohorts. RESULTS:There were significant differences in operative time among cohorts (p < 0.001), highest among the periprosthetic fracture group (164.2 ± 59.8 min). Reoperation rate was greatest in the extensor mechanism disruption cohort (50.0 %, p = 0.009). Total cost differed significantly among groups (p < 0.001), which was highest among the implant failure cohort (134.6 % of mean) and lowest for component malpositioning cohort (90.2 % of mean). Similarly, there were significant differences in direct cost (p < 0.001) which was highest in the periprosthetic fracture cohort (138.5 % of mean), and lowest in the implant failure cohort (90.5 % of mean). There were no differences in discharge disposition, or number of re-revisions among all groups. CONCLUSIONS:Operative time, components revised, LOS, readmissions, reoperation rate, total cost and direct cost following aseptic rTKA varied significantly between different revision indications. These differences should be noted for preoperative planning, resource allocation, scheduling, and risk-stratification. LEVEL OF EVIDENCE/METHODS:III, retrospective observational analysis.