Purpose: Total hip arthroplasty (THA) has become a highly frequent orthopaedic procedure. Multiple approaches have been made to design the femoral component for THA with a mechanical behaviour as close as possible to a natural femur. The aim of this study was to compare different combinations of design and biomechanical properties of THA prostheses and their impact on stress shielding of the periprosthetic bone. Methods: Virtual implantation of different stem designs (straight standard stem, straight short stem, anatomical short stem) by finite element analysis based on in vivo data from computer tomography was performed. For each stem, three grades of stiffness were generated, followed by a strain analysis. Results: Reduction of stem stiffness led to less stress shielding. Implantation of an anatomical short-stem prosthesis with low stiffness provided the most physiological strain-loading effect (p < 0.001). Conclusion: A combination of a short and an anatomically designed stem with a low stiffness might provide a more physiological strain transfer during THA. Biomechanical properties of the femoral component for THA should be considered as a multifactorial function of dimensions, design, and stiffness.

Osteoarthritis of the knee is common and often leads to significant physical disability. While classic conservative therapeutic approaches aim for symptoms like pain and inflammation, procedures like the intraarticular application of hyaluronic acids (HA) or platelet-rich plasma (PRP) are thought to stimulate the endogenous HA production, stop catabolism of cartilage tissue, and promote tissue regeneration. To analyse whether the positive effects of PRP injections are associated with the level of cartilage damage, patient satisfaction with the treatment was correlated with the level of knee joint osteoarthritis quantified by MRI. PRP was performed with a low-leukocyte autologous conditioned plasma (ACP) system in 59 patients. A pre-treatment MRI was performed and a Whole-Organ MRI Score (WORMS) was used to score the level of knee osteoarthritis by 14 features: integrity of the cartilage, affection of the bone marrow, subcortical cysts, bone attrition, osteophytes, integrity of the menisci and ligaments, presence of synovitis, loose bodies, and periarticular cysts. A multivariate analysis with ordinary least squares regressions was used. Although pain symptoms and severity of clinical osteoarthritis symptoms decreased, regression analysis could not detect a correlation between the degree of cartilage damage measured by the WORMS score and a positive response to PRP therapy. This study suggests that intraarticular injection of PRP might improve osteoarthritis symptoms and reduces the pain in patients suffering from osteoarthritis of the knee joint independent from the level of cartilage damages quantified by the whole-organ MRI scoring method WORMS.

Hallux valgus disease is a common deformity of the forefoot. There are currently more than 100 surgical approaches for operative treatment. Because hypermobility of the first tarsometatarsal joint is considered to be causal for hallux valgus disease, fusion of the tarsometatarsal joint is an upcoming surgical procedure. Despite the development of new and increasingly stable fixation devices like different locking plates, malunion rates have been reported in 5 to 15% of cases. Biomechanical comparison of three commonly used fixation devices (a dorsal locking plate, a plantar locking plate, and an intramedullary fixation device) was performed by weight-bearing simulation tests on synthetic bones. Initial compression force and stiffness during simulation of postoperative weight-bearing were analysed. Fixation of the first tarsometatarsal joint with the plantar plate combination demonstrated a higher stiffness compared to fixation with the intramedullary implant or the medial locking plate. The intramedullary device provided the highest initial compression force. Failure was detected in the following ranking: (1) the angle-stable intramedullary fixation device, (2) the medial located plate, and (3) the plantar locking plate. The intramedullary device demonstrated the highest initial compression force of the three tested implants. The plantar locking plate showed the best overall stability during weight-bearing simulation. Further clinical research is necessary to analyse if the intramedullary fixation device needs a longer period of non-weight-bearing to reach a better non-union rate compared to the plantar locking plate.

The main objective of every new development in total hip arthroplasty (THA) is the longest possible survival of the implant. Periprosthetic stress shielding is a scientifically proven phenomenon which leads to inadvertent bone loss. So far, many studies have analysed whether implanting different hip stem prostheses result in significant preservation of bone stock. The aim of this preclinical study was to investigate design-depended differences of the stress shielding effect after implantation of a selection of short-stem THA-prostheses that are currently available. Based on computerised tomography (CT), a finite elements (FE) model was generated and a virtual THA was performed with different stem designs of the implant. Stems were chosen by osteotomy level at the femoral neck (collum, partial collum, trochanter sparing, trochanter harming). Analyses were performed with previously validated FE models to identify changes in the strain energy density (SED). In the trochanteric region, only the collum-type stem demonstrated a biomechanical behaviour similar to the native femur. In contrast, no difference in biomechanical behaviour was found between partial collum, trochanter harming and trochanter sparing models. All of the short stem-prostheses showed lower stress-shielding than a standard stem. Based on the results of this study, we cannot confirm that the design of current short stem THA-implants leads to a different stress shielding effect with regard to the level of osteotomy. Somehow unexpected, we found a bone stock protection in metadiaphyseal bone by simulating a more distal approach for osteotomy. Further clinical and biomechanical research including long-term results is needed to understand the influence of short-stem THA on bone remodelling and to find the optimal stem-design for a reduction of the stress shielding effect.

Due to an increasing demand in health care services plans to substitute selective physician-conducted medical activities have become attractive. Because administration of a blood transfusion is a highly standardized procedure, it might be evaluated if obtaining a patient’s consent for a blood transfusion can be delegated to allied healthcare professionals. Physicians and patients perceive risks of transfusions differently. However, it is unknown how allied healthcare professionals perceive risks of transfusion-associated adverse events. Patients (n = 506) and allied healthcare professionals (n = 185) of an academic teaching hospital were asked to quantify their concerns about transfusions including five predefined transfusion-associated risks and their incidences. Blood transfusions were considered to be generally harmful by 10.9% of patients and 14.6% of caregivers (P = 0.180). Among all surveyed patients, 36.8% were worried about infection-transmissions (caregivers: 27.6%; P = 0.024). Compared to 5.4% of caregivers, 13.6% of patients believed infection-transmission was a frequent complication (P = 0.003). Caregivers ranked the risks of receiving an AB0-mismatch transfusion (caregivers: 29.7% vs. patients: 19.2%, P = 0.003) or a transfusion-associated allergic reaction (caregivers: 17.3% vs. patients: 11.1%, P = 0.030) significantly higher than patients and were aware of the high incidence of transfusion-associated fever (caregivers: 17.8% vs. patients: 8.3%, P < 0.001). A significant part of interviewees perceived transfusions as a general health hazard. Patients perceived infection-transmissions as the most frequent and greatest transfusion-associated threat while caregivers focused on fatal AB0-mismatch transfusions and allergic reactions. Understanding the patients’ main concerns about blood transfusions and considering that these concerns might differ from the view of healthcare professionals might improve the process of shared decision making.