Current concepts in hip–spine relationships: making them practical for total hip arthroplasty

Hip, spine, and pelvis move in coordination with one another during activity, forming the lumbopelvic complex (LPC). These movements are characterized by the spinopelvic parameters sacral slope, pelvic tilt, and pelvic incidence, which define a patient’s morphotype. LPC kinematics may be classified by various systems, the most comprehensive of which is the Bordeaux Classification. Hip–spine relationships in total hip arthroplasty (THA) may influence impingement, dislocation, and edge loading. Historical ‘safe zones’ may not apply to patients with impaired spinopelvic mobility; adjustment of cup inclination and version and stem version may be necessary to achieve functional orientation and avert complications. Stem design, bearing surface (including dual mobility), and head size are part of the armamentarium to treat abnormal hip–spine relationships. Special attention should be directed to patients with adult spine deformity or fused spine because they are at increased risk of complications after THA.

Study of STEM for Sustainability in Design Education: Framework for Student Learning and Outcomes with Design for a Disaster Project

STEM has successfully introduced an interdisciplinary education model that can be used for training students to develop skillsets for the 21st century. STEM Education for Sustainability (STEM4S) expands the scope of education to meet rapidly changing global challenges, such as climate change and SDGs by the United Nations, which require the multidisciplinary curriculum to be integrated into STEM. Design-based tasks play a significant role in STEM education by promoting students’ critical thinking and problem-solving abilities. While STEM successfully employs design, design education currently conducts subjective procedures and lacks the framework for adopting the critical-thinking process. Therefore, design education can develop students’ cognitive skills by reflecting on STEM learning experiences. This study articulates the framework for design education by investigating problem-based and project-based learning and the double-diamond diagram for innovation. The goal of this study was to apply these observations and formulate the framework for STEM4S. This study examined the framework adopted at the National Taiwan Normal University in the Department of Design, with qualitative analysis of participants and quantitative analysis of questionnaire results. Finally, the researchers discuss the research questions and future applications of this framework.

Retrieval analysis of neck fracture on uni-modular total hip arthroplasty stems: The contributions of material processing and stem design

Total hip arthroplasty stem fracture is an important contributor to morbidity rate and increases the cost of revision surgery. Failure is usually caused by issues related to overload, inadequate stem support, inappropriate stem design or dimensions and material processing. In this study, the role of the relationship between material characterization and biomechanical performance in the fracture of retrieved stems was explored. The stems were manufactured with forged stainless steel, had the same length, 12/14 trunnion, and 28-mm head. These stems were evaluated by macroscopic and microscopic examination to identify the causes of premature failure. Each stem was sectioned into four regions, and the cross-sections were used for the microhardness and grain size analysis. Finite element analysis (FEA) was carried out, considering the stem positioned at the femur, a musculoskeletal model, and biomechanical loading. All stems had fractured through a fatigue mechanism, mainly a unidirectional bending loading condition, with crack nucleation on the lateral side and propagation on the medial side. The numerical analysis revealed maximum mechanical stress on the lateral side of the stem neck, but this was below the yield stress calculated via the hardness. The use of a shorter head neck length could reduce the maximum mechanical stress at the neck. At a cross-section near the plane of the stem fracture, the hardness was lower than that normally reported by the ASM, and there were heterogonous and coarse grain sizes on the lateral side. The main cause of failure of the two stems analyzed was a combination of low hardness and coarse grain size, due to inappropriate materials processing, worsen by a high level of stress on the lateral side of the neck due to the large stem-head offset selected by the orthopedic surgeon.

Is group work beneficial for producing creative designs in STEM design education?

Creativity is a significant element in design education, and frequently a significant competency during recruitment for design professions. Group work and individual work are widely employed in higher education. Many studies have highlighted the merits of employing group work in design education, cultivating collaborative design abilities and fostering sought-after employability skills. Although the benefits of group work in design practice and education are widely recognised, few studies have shown evidence that group work outperforms individual work regarding creative design activities in higher education contexts. Therefore, the aim of this research is to explore whether group or individual work is more beneficial for fostering students in generating creative designs in STEM design education. A case study, involving two cohorts of second-year undergraduate students studying a UK Engineering degree Industrial Design programme, is reported. The case study compares the design outputs produced by the two cohorts tackling the same design challenge in a product design module but employing individual and group work, respectively. The case study results show that no significant differences have been found between the design outputs produced by group work and individual work, considering novelty, usefulness and overall creativity. Further analysis reveals that a student’s academic performance is not significantly related to the level of creativity of the design produced. This research indicates design educators should employ both group and individual work to complement each other in design education, and suggests potential solutions to enhance students’ design creativity.

Total hip arthroplasty with ultra-short uncemented stem in patients with osteonecrosis of the femoral head: mid-term results

Background: Mid-term results (clinical and radiographic) of ultra-short anatomical cementless stem total hip arthroplasty (THA) in patients with osteonecrosis of the femoral head (ONFH) has not often been presented. The aim of this study is to evaluate THA using the Proxima stem in patients with ONFH in the mid-term. Methods: The study consists of 73 patients (97 THAs) with a Proxima stem implanted between 2006 and 2015. The mean age of patients was 47.4 years, with a mean follow-up 105.2 months. The clinical results include preoperative and postoperative Harris Hip Scores (HHSs). Radiological follow-up reports on stem migration, bony trabecular development and radiolucent lines. The complications and revisions were registered. Kaplan-Meier survival analysis was performed to determine the implant survival. Results: The average HHS improved significantly from 40.3 preoperatively to 98.0 at the final evaluation ( p ˂ 0.0001). Stem migration (subsidence and “varisation”) was observed in 11 hips (in 9 of them up to 6th postoperative month without any further progression, in 2 with progressive migration and radiological loosening). Bony trabecular development was detected in modified Gruen zones (1,2,4,6,7 for Proxima stem): in zone 1 (0%), 2 (67.0%), 4 (64.9%), 6 (64.9%), 7 (0%). Radiolucent lines were observed in 1 cup and 6 stems (2 were loose, 4 with fibrous stable fixation). Complications were found in 5 hips (5.1%): squeezing hip once, repeated dislocation in 1, 1 early deep infection, and 2 loose stems. 2 hips (2.1%) were revised (dislocation, infection). The implant survival was 98.9% and 97.9% clinically and radiologically, respectively. Conclusions: Observations in the mid-term show that the clinical and radiological results of the Proxima stem in patients with ONFH are promising. The stem design preserves the proximal femoral bone stock. The bony trabecular appearance confirms physiological proximal femoral load transmission.

Vancouver B and C periprosthetic fractures around the cemented Exeter Stem: sex is associate with fracture pattern

Introduction The aim of this study was to identify factors associated with the level of periprosthetic fracture involving a cemented polished tapered stem: Vancouver B or Vancouver C. Methods A retrospective cohort study of 181 unilateral periprosthetic fractures involving Exeter stems was assessed by three observers (mean age 78.5, range 39–103; mean BMI 27.1, 17–39; 97 (54%) male). Patient demographics, deprivation scores, BMI and time since primary prosthesis were recorded. Femoral diameter, femoral cortical thickness, Dorr classification and distal cement mantle length were measured from calibrated radiographs. Interobserver reliability was calculated using intraclass correlation coefficients (ICCs). Univariate and multivariate analysis was performed to identify associations with Vancouver B or C fractures. Results 160/181 (88%) Vancouver B and 21/181 (12%) Vancouver C-level fractures occurred at a mean of 5.9 ± 5.4 years (0.2–26.5) following primary surgery. Radiographic measurements demonstrated excellent agreement (ICC > 0.8, p < 0.001). Mortality was significantly higher following Vancouver C compared to B fractures: 90 day 14/160 Vs 5/21 (p = 0.05); 1 year 29/160 Vs 8/21 (p = 0.03). Univariate analysis demonstrated that Vancouver C fractures were associated with female sex, bisphosphonate use, cortical bone thickness, and distal cement mantle length (p < 0.05). On multivariate analysis, only female sex was an independent predictor of Vancouver C-level fractures (R2 =0.354, p = 0.005). Conclusion Most PFFs involving the Exeter stem design are Vancouver B-type fractures and appear to be independent of osteoporosis. In contrast, Vancouver C periprosthetic fractures display typical fragility fracture characteristics and are associated with female sex, thinner femoral cortices, longer distal cement mantles and high mortality.

Short-stem total hip arthroplasty is not associated with an earlier return to work compared to a straight-stem design

Return to work (RTW) has been specifically identified as a high priority in patients undergoing total hip arthroplasty (THA). This investigation sought to assess the effect of the stem design on patients’ RTW. Secondly, the study aimed to identify risk factors that lead to a delayed RTW. Questionnaires inquiring about RTW, employment history, educational level, type of work, physical demands and joint awareness were administered by post. Further data were collected from patients’ hospital records. 176 patients who underwent THA using a short-stem and 97 patients using a straight-stem design were compared. The median return to work time was 10 weeks [IQR 7–14 weeks], with no significant difference between the two groups (short stems vs. straight stems; 10 [IQR 7–14] vs. 11 [7.5–13.5] weeks; p = 0.693). In the multivariate linear regression analysis, self-employment vs. employee (p = 0.001), dimension of preoperative workload (p = 0.001), preoperative sick leave (p < 0.001), and hospital length of stay (LOS) (p < 0.001) independently affected the period until work was resumed. The Forgotten-Joint-Score-12 showed no significant difference between the two groups. The data show that the majority of THA patients can expect to resume work and stem design has no impact on RTW. Employees with preoperative sick leave, prolonged hospital LOS and low workload are at higher risk for a delayed RTW.