Acetabular Component Positioning in Primary THA via an Anterior, Posterolateral, or Posterolateral-navigated Surgical Technique

The purpose of this study was to compare the acetabular component alignment in patients undergoing primary total hip arthroplasty (THA) via 3 surgical techniques: direct anterior using intraoperative fluoroscopy, posterolateral using an external alignment guide (posterolateral conventional), and posterolateral using computer navigation (posterolateral navigated). Two surgeons performed the direct, anterior THAs; 2 surgeons performed the posterolateral-conventional THAs; and 1 surgeon performed the posterolateral-navigated THAs. The most recent 110 THAs performed using each approach were reviewed, and Einsel-Bild-Roentgen analysis software was used to measure the acetabular component abduction and anteversion. One-way analysis of variance showed the anterior cohort to have a more horizontal alignment of the acetabular component (P,.001); 90.9% of the acetabular components in the posterolateral-navigated cohort were within 40°610° and 15°610° for both acetabular abduction and anteversion, respectively, vs 70% in the posterolateral-conventional (P,.001), and 68.2% in the anterior cohort (P,.001). The anterior technique using intraoperative fluoroscopy does not improve acetabular positioning compared with the conventional, posterolateral technique

Fixed-bearing Medial Unicompartmental Knee Arthroplasty Restores Neither the Medial Pivoting Behavior Nor the Ligament Forces of the Intact Knee in Passive Flexion

Medial unicompartmental knee arthroplasty (UKA) is an accepted treatment for isolated medial osteoarthritis. However, using an improper thickness for the tibial component may contribute to early failure of the prosthesis or disease progression in the unreplaced lateral compartment. Little is known of the effect of insert thickness on both knee kinematics and ligament forces. Therefore, a computational model of the tibiofemoral joint was used to determine how non-conforming, fixed bearing medial UKA affects tibiofemoral kinematics and tension in the medial collateral ligament (MCL) and the anterior cruciate ligament (ACL) during passive knee flexion. Fixed bearing medial UKA could not maintain the medial pivoting that occurred in the intact knee from 0° to 30° of passive flexion. Abnormal anterior-posterior (AP) translations of the femoral condyles relative to the tibia delayed coupled internal tibial rotation, which occurred in the intact knee from 0° to 30° flexion, but occurred from 30° to 90° flexion following UKA. Increasing or decreasing tibial insert thickness following medial UKA also failed to restore the medial pivoting behavior of the intact knee despite modulating MCL and ACL forces. Reduced AP constraint in non-conforming medial UKA relative to the intact knee leads to abnormal condylar translations regardless of insert thickness even with intact cruciate and collateral ligaments. This finding suggests that the conformity of the medial compartment as driven by the medial meniscus and articular morphology plays an important role in controlling AP condylar translations in the intact tibiofemoral joint during passive flexion

Man or Machine, poster

I believe design has the ability to perform a function in the most efficient, beautiful, and essential way. I favor simplicity. I think there is something beautiful about the essential, the design stripped down to its core. With all the power of design, I believe I have a responsibility to ensure that my designs help people, help our world, and therefore foster a better future

Man or Machine, poster

I believe design has the ability to perform a function in the most efficient, beautiful, and essential way. I favor simplicity. I think there is something beautiful about the essential, the design stripped down to its core. With all the power of design, I believe I have a responsibility to ensure that my designs help people, help our world, and therefore foster a better future

Characterizing the Magnitude of and Risk Factors for Functional Limb Lengthening in Patients Undergoing Primary Total Knee Arthroplasty

Background: There is little data on the magnitude and factors for functional leg lengthening after primary total knee arthroplasty (TKA). Questions/Purpose: We sought to determine the incidence of and risk factors for functional leg lengthening after primary TKA. Methods: We retrospectively reviewed consecutive unilateral primary TKAs at a single institution from 2015 to 2018. Of the 782 TKAs included, 430 (55%) were performed in women; the mean age was 66 years, and the mean body mass index was 29 kg/m2. Preoperatively, 541 (69%) knees were varus deformities and 223 (29%) were valgus deformities. Hip to ankle biplanar radiographs were obtained preoperatively and 6 weeks postoperatively for all patients. Two independent researchers measured leg length, coronal plane deformity, lateral knee flexion angle, and overall mechanical alignment on all preoperative and postoperative radiographs. Results: The mean overall ipsilateral functional leg lengthening was 7.0 mm. Seven hundred knees (90%) were overall functionally lengthened, including 462 (59%) knees lengthened \u3e5 mm and 250 (31%) knees lengthened 10 mm or more. A valgus deformity and coronal plane deformity of 10° or more were significant risk factors for increased functional lengthening. Patients with severe valgus deformities (\u3e10°) had the largest amount of functional lengthening, at a mean of 13.5 mm. Conclusion: After primary TKA, 90% of limbs are functionally lengthened, including roughly one-third over a centimeter. Valgus knee deformities and severe deformities (\u3e10°) were significant risk factors for increased limb lengthening

Validation of the HOOS, JR: A Short-form Hip Replacement Survey

BACKGROUND: Patient-reported outcome measures (PROMs) are increasingly in demand for outcomes evaluation by hospitals, administrators, and policymakers. However, assessing total hip arthroplasty (THA) through such instruments is challenging because most existing measures of hip health are lengthy and/or proprietary. QUESTIONS/PURPOSES: The objective of this study was to derive a patient-relevant short-form survey based on the Hip disability and Osteoarthritis Outcome Score (HOOS), focusing specifically on outcomes after THA. METHODS: We retrospectively evaluated patients with hip osteoarthritis who underwent primary unilateral THA and who had completed preoperative and 2-year postoperative PROMs using our hospital\u27s hip replacement registry. The 2-year followup in this population was 81% (4308 of 5351 patients). Of these, 2371 completed every item on the HOOS before surgery and at 2 years, making them eligible for the formal item reduction analysis. Through semistructured interviews with 30 patients, we identified items in the HOOS deemed qualitatively most important to patients with hip osteoarthritis. The original HOOS has 40 items, the four quality-of-life items were excluded a priori, five were excluded for being redundant, and one was excluded based on patient-relevance surveys. The remaining 30 items were evaluated using Rasch modeling to yield a final six-item HOOS, Joint Replacement (HOOS, JR), representing a single construct of hip health. We calculated HOOS, JR scores for the Hospital for Special Surgery (HSS) cohort and validated this new score for internal consistency, external validity (versus HOOS and WOMAC domains), responsiveness to THA, and floor and ceiling effects. Additional external validation was performed using calculated HOOS, JR scores in collaboration with the Function and Outcomes Research for Comparative Effectiveness in Total Joint Replacement (FORCE-TJR) nationally representative joint replacement registry (n = 910). RESULTS: The resulting six-item PROM (HOOS, JR) retained items only from the pain and activities of daily living domains. It showed high internal consistency (Person Separation Index, 0.86 [HSS]; 0.87 [FORCE]), moderate to excellent external validity against other hip surveys (Spearman\u27s correlation coefficient, 0.60-0.94), very high responsiveness (standardized response means, 2.03 [95% CI, 1.84-2.22] [FORCE]; and 2.38 [95% CI, 2.27-2.49] [HSS]), and favorable floor (0.6%-1.9%) and ceiling (37%-46%) effects. External validity was highest for the HOOS pain (Spearman\u27s correlation coefficient, 0.87 [95% CI, 0.86-0.89] [HSS]; and 0.87 [95% CI, 0.84-0.90] [FORCE]) and HOOS activities of daily living (Spearman\u27s correlation coefficient, 0.94 [95% CI, 0.93-0.95] [HSS]; and 0.94 [95% CI, 0.93-0.96] [FORCE]) domains in the HSS validation cohort and the FORCE-TJR cohort. CONCLUSIONS: The HOOS, JR provides a valid, reliable, and responsive measure of hip health for patients undergoing THA. This short-form PROM is patient relevant and efficient. LEVEL OF EVIDENCE: Level III, diagnostic study