Faculty Bibliography

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.

Periprosthetic joint infection (PJI) remains a major source of morbidity after total knee arthroplasty (TKA). The risk of recurrent infection has been more extensively studied than the risk of mechanical failure. We sought to define the incidence of instability after revision TKA for PJI and to compare this incidence with that for revision TKA for instability. We retrospectively reviewed patients treated by 4 arthroplasty surgeons at 1 institution. The primary outcome was a new diagnosis of clinical instability after index revision. We analyzed potential risk factors that may contribute to postoperative instability after PJI, including demographic characteristics, implant alignment, number of previous procedures, level of constraint during index revision, and type of spacer used. Patients were matched 1:1 with patients undergoing revision TKA for instability. Continuous variables were compared with Student's t test for normally distributed variables and Mann-Whitney U test for non-normal variables. Categorical variables were compared with Fisher's exact test. Thirty-seven patients who underwent revision TKA for PJI were identified. Twelve (32.4%) had clinical instability after revision, compared with only 3 (8.1%) in the matched cohort (P=.019). Use of a revision, midlevel constraint device in the PJI cohort did not correlate with a lower risk of instability (P=.445). A greater number of previous surgical procedures increased the likelihood of instability (P=.041). Revision TKA for PJI is associated with a high risk of subsequent instability. Midlevel constrained implants may not be sufficient to prevent instability. A focus on soft tissue tension and a lower threshold for increasing constraint may be prudent in this cohort. [Orthopedics. 2022;45(3):145-150.].

INTRODUCTION/UNASSIGNED:The direct anterior approach (DAA) and the posterior approach (PA) are 2 common total hip arthroplasty (THA) exposures. This prospective study quantitatively compared changes in periarticular muscle volume after DAA and PA THA. MATERIALS/UNASSIGNED:19 patients undergoing THA were recruited prospectively from the practices of 3 fellowship-trained hip surgeons. Each surgeon performed a single approach, DAA or PA. Enrolled patients underwent a preoperative MRI of the affected hip and two subsequent postoperative MRIs at around 6 weeks and 6 months after surgery. Clinical evaluations were done by Harris Hip Score at each follow-up interval. RESULTS/UNASSIGNED:MRIs or 10 DAA and 9 PA patients were analysed. Groups did not differ significantly with regard to BMI, age, or preoperative muscle volume. 1 DAA patient suffered a periprosthetic fracture and was excluded from the study. DAA hips showed significant atrophy in the obturator internus (-37.3%) muscle at early follow-up, with persistent atrophy of this muscle at the final follow-up. PA hips showed significant atrophy in the obturator internus (-46.8%) and externus (-16.0%), piriformis (-8.12%), and quadratus femoris muscles (-13.1%) at early follow-up, with persistent atrophy of these muscles at final follow-up. Loss of anterior capsular integrity was present at final follow-up in 2/10 DAA hips while loss of posterior capsular integrity was present in 5/9 PA hips. There was no difference in clinical outcomes. DISCUSSION/UNASSIGNED:This study demonstrates that DAA showed less persistent muscular atrophy than PA. Regardless of surgical approach, a muscle whose tendon is detached from its insertion is likely to demonstrate persistent atrophy 6 months following THA. Although the study was not powered to compare clinical outcomes, it should be noted that no significant difference in patient outcomes was observed.

Purpose/UNASSIGNED:Use of dual mobility (DM) articulations can reduce the risk of instability in both primary and revision total hip arthroplasty (THA). Knowledge regarding the impact of this design on patient-reported outcome measures (PROMs) is limited. This study aims to compare clinical outcomes between DM and fixed bearing (FB) prostheses following primary THA. Materials and Methods/UNASSIGNED:All patients who underwent primary THA between 2011-2021 were reviewed retrospectively. Patients were separated into three cohorts: FB vs monoblock-D vs modular-DM. An evaluation of PROMs including HOOS, JR, and FJS-12, as well as discharge-disposition, 90-day readmissions, and revisions rates was performed. Propensity-score matching was performed to limit significant demographic differences, while ANOVA and chi-squared test were used for comparison of outcomes. Results/UNASSIGNED:=0.608) between the groups. Conclusion/UNASSIGNED:DM bearings yield PROMs similar to those of FB implants in patients undergoing primary THA. Although DM implants are utilized more often in patients at higher-risk for instability, we suggest that similar patient satisfaction may be attained while achieving similar dislocation rates.

PURPOSE/OBJECTIVE:Back pain may both decrease patient satisfaction after TKA and confound outcome assessment in satisfied patients. Our primary objective was to determine whether preoperative back pain is associated with differences in postoperative patient-reported outcome measures (PROMs). METHODS:We retrospectively reviewed 234 primary TKA patients who completed PROMs preoperatively and 12 weeks postoperatively, which included a back pain questionnaire, the Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS JR) and the Forgotten Joint Score-12 (FJS-12). Cohorts were defined based on the severity of preoperative back pain (none, mild, moderate and severe) and compared. Demographics were compared using ANOVA and Chi-square analysis. Univariate ANCOVA analysis was utilized to compare PROMs while accounting for significant demographic differences. RESULTS:Both preoperative KOOS JR scores (none: 47.90, mild: 47.61, moderate: 44.61 and severe: 38.70; p = 0.013) and 12-week postoperative KOOS JR scores (none: 61.24, mild: 64.94, moderate: 57.48 and severe: 57.01; p = 0.012) had a statistically significant inverse relationship with regard to the intensity of preoperative back pain. Although FJS-12 scores at the 12-week postoperative period trended lower with increasing levels of preoperative back pain (p = 0.362), it did not reach statistical significance. Patients who reported severe back pain preoperatively achieved the largest delta improvement from baseline compared to those with lesser pain intensity (p = 0.003). Patients who had a 2-grade improvement in their back pain achieved significantly higher KOOS JR scores 12 weeks postoperatively compared to patients with either 1-grade or no improvement (63.53 vs. 55.98; p = 0.042). Both preoperative (47.99 vs. 41.11; p = 0.003) and 12-week postoperative (64.06 vs. 55.73; p < 0.001) KOOS JR scores were statistically higher for those who reported mild or no back pain pre-and postoperatively than those who reported moderate or severe back pain pre-and postoperatively. CONCLUSION/CONCLUSIONS:Knee pain and back pain both exert negative effects on outcome instruments designed to measure pain and function. Although mean improvement from pre- to postoperative KOOS JR scores for patients with severe pre-existing back pain was higher than their counterparts, this statistical difference is likely not clinically significant. This implies that all patients may experience similar benefits from TKA despite the presence or absence of back pain. Attempts to measure TKA outcomes using PROMs should seek to control for lumbago and other sources of body pain. Level of Evidence IIIRetrospective Cohort Study.

Haptic robotic-arm-assisted total knee arthroplasty (RATKA) seeks to leverage three-dimensional planning, intraoperative assessment of ligament laxity, and guided bone preparation to establish and achieve patient-specific targets for implant position. We sought to compare (1) operative details, (2) knee alignment, (3) recovery of knee function, and (4) complications during adoption of this technique to our experience with manual TKA. We compared 120 RATKAs performed between December 2016 and July 2018 to 120 consecutive manual TKAs performed between May 2015 and January 2017. Operative details, lengths of stay (LOS), and discharge dispositions were collected. Tibiofemoral angles, Knee Society Scores (KSS), and ranges of motion were assessed until 3 months postoperatively. Manipulations under anesthesia, complications, and reoperations were tabulated. Mean operative times were 22 minutes longer in RATKA (p < 0.001) for this early cohort, but decreased by 27 minutes (p < 0.001) from the first 25 RATKA cases to the last 25 RATKA cases. Less articular constraint was used to achieve stability in RATKA (93 vs. 55% cruciate-retaining, p < 0.001; 3 vs. 35% posterior stabilized (PS), p < 0.001; and 4 vs. 10% varus-valgus constrained, p_ = _0.127). RATKA had lower LOS (2.7 vs. 3.4 days, p < 0.001). Discharge dispositions, tibiofemoral angles, KSS, and knee flexion angles did not differ, but manipulations were less common in RATKAs (4 vs. 17%, p = 0.013). We observed less use of constraint, shorter LOS, and fewer manipulations under anesthesia in RATKA, with no increase in complications. Operative times were longer, particularly early in the learning curve, but improved with experience. All measured patient-centered outcomes were equivalent or favored the newer technique, suggesting that RATKA with patient-specific alignment targets does not compromise initial quality. Observed differences may relate to improved ligament balance or diminished need for ligament release.

BACKGROUND:Guidelines support aspirin thromboprophylaxis for primary total hip and knee arthroplasty (THA and TKA) but supporting evidence has come from high volume centers and the practice remains controversial. METHODS:We studied 4562 Medicare patients who underwent elective primary THA (1736, 38.1%) or TKA (2826, 61.9%) at 9 diverse hospitals. Thirty-day claims data were combined with data from the health system's electronic medical records to compare rates of venous thromboembolism (VTE) between patients who received prophylaxis with: (1) aspirin alone (47.3%), (2) a single, potent anticoagulant (29%), (3) antiplatelet agents other than aspirin or multiple anticoagulants (21.5%), or (4) low-dose subcutaneous unfractionated heparin or no anticoagulation (2.2%). Sub-analyses separately evaluating THA, TKA and cases from lower volume hospitals (n = 975) were performed. RESULTS:The 30-day VTE incidence was 0.6% (29/4562). VTE rates were equal in patients receiving aspirin and those receiving a single potent anticoagulant (0.5% in both groups). Patients with VTE were significantly older than patients without VTE (mean 76.5 vs. 73.1 years, P = 0.04). VTE rate did not associate with sex or hospital case volume. On bivariate analysis considering age, aspirin did not associate with greater VTE risk compared to a single potent anticoagulant (OR = 2.1, CI = 0.7-6.3) with the numbers available. Odds of VTE were increased with use of subcutaneous heparin or no anticoagulant (OR = 6.4, CI = 1.2-35.6) and with multiple anticoagulants (OR = 3.6, CI = 1.1-11.2). THA and TKA demonstrated similar rates of VTE (0.5% vs. 0.7%, respectively, P = 0.43). Of 975 cases done at lower volume hospitals, 387 received aspirin, none of whom developed VTE. CONCLUSIONS:This study provides further support for aspirin as an effective form of pharmacological VTE prophylaxis after total joint arthroplasty in the setting of a multi-modal regimen using 30-day outcomes. VTE occurred in 0.7% of primary joint arthroplasties. Aspirin prophylaxis did not associate with greater VTE risk compared to potent anticoagulants in the total population or at lower volume hospitals.

INTRODUCTION:Total hip arthroplasty (THA) in the setting of developmental dysplasia of the hip (DDH) presents more inherent complexities than routine primary THA for osteoarthritis. These include acetabular bone deficiency, limb length discrepancy (LLD), and abnormal femoral anteversion. Three-dimensional planning and robot-assisted (RA) bone preparation may simplify these complex procedures and make them more reproducible. The purpose of this study was to evaluate radiographic and clinical outcomes in a cohort of patients who had DDH and underwent an RA THA. MATERIALS AND METHODS:We retrospectively analyzed 26 DDH patients who underwent RA THA by a single surgeon between 2013 and 2019. Their mean age was 54 years (range, 29 to 72 years) and mean follow up was approximately two years. Medical records were reviewed for demographics, clinical scores, Crowe classifications, and complications. There were thirteen Crowe I and seven Crowe II DDH hips, who were routinely managed with primary cementless implants. Two patients who had Crowe III and four patients who had Crowe IV DDH were also identified. All hips were reconstructed with cementless hemispherical acetabular components with or without the use of screws, but no acetabular augments or bulk allografts. Implants allowing control of femoral anteversion were selected in 23.1% of cases, including all six cases with Crowe III or IV dysplasia, and the need for these implants was uniformly identified using preoperative information about femoral version provided by the three-dimensional planning software. No patient was managed with a shortening femoral osteotomy. Postoperative radiographs were examined for LLD, center of rotation (COR), cup position (inclination and anteversion), and component osseous-integration. RESULTS:Mean radiographic LLD was 1.7mm (range, -9 to +14) in patients who had Crowe I DDH, and there was no clinical LLDs greater than 5mm observed. Although patients who had Crowe II and greater DDH had a mean radiographic LLD of -11.6mm (range, -26 to +2.2), again no clinical LLD greater than 5mm was observed other than one patient who had bilateral Crowe II DDH in whom 10mm of clinical lengthening was accepted at the index arthroplasty with the plan to match lengths when her contralateral THA was performed. There were no cases of dislocation or acetabular fixation failure. One patient who had a femoral deformity and an intra-osseous blade plate from a prior femoral osteotomy suffered a failure of femoral osseous-integration, resulting in revision. A 32-point increase in mean modified Harris Hip Score (mHHS) was found (p=0.002), from 48 points preoperatively to 80 points postoperatively. DISCUSSION:RA THA provides an excellent option for the arthroplasty surgeon to both preoperatively localize and characterize the acetabular deficiency, while providing a targeted, optimal, and secure placement of the components intraoperatively. Our results suggest favorable outcomes when compared to previous research on manual THA in DDH. Further studies, including comparative analyses, could discern possible advantages over traditional THA without robotic assistance in DDH. CONCLUSION:Total hip arthroplasty (THA) in the setting of developmental dysplasia presents more inherent complexities than routine primary THA. Robotic-assisted THA may simplify these complex procedures.

INTRODUCTION/UNASSIGNED:Approximately half of dislocating total hip arthroplasties (THAs) demonstrate acetabular component position within traditional safe zones. It is unclear if postoperative functional acetabular position can be reliably improved by considering preoperative pelvic tilt. We investigated whether standing cup position targets could be more accurately achieved by considering preoperative standing pelvic tilt in addition to bone landmarks when planning for robot-assisted THA. METHODS/UNASSIGNED:We reviewed 146 THAs performed by a single surgeon using computed tomography-based 3-dimensional planning and robotic technology to guide acetabular reaming and component insertion. Planning for 73 consecutive cases started at 40° of inclination and 22° of anteversion relative to the supine functional plane and was adjusted to better match native hip anatomy. Planning for the next 73 cases was modified to consider standing pelvic position based on standing preoperative radiographs. We compared groups to determine the rate when cups were placed outside our standing targets of 15-30° anteversion and 35-50° inclination. RESULTS/UNASSIGNED: = 0.352). The range of functional positions was narrower in the functional planning group: 35.7-47.5° versus 31.8-54.9° of inclination and 16.7-35.0° versus 10.1-35.9° of anteversion. DISCUSSION/UNASSIGNED:Our results suggest enhanced planning that considers pelvic tilt, when coupled to a precision tool to achieve the plan, can reliably achieve target standing component positions. Considering preoperative functional pelvic position may improve postoperative functional acetabular component placement in THA, but the clinical benefit of this has yet to be confirmed.