Introduction: Femoral neck fracture is one of the most common orthopaedic traumas affecting the elderly population. The standard treatment method is hip hemiarthroplasty and total hip arthroplasty. In hip hemiprostheses surgeons mainly have to reconstruct the femoral offset and limbs' length to obtain the correct gait biomechanics and a satisfactory surgical outcome. The aim of this study is to examine the radiological results of patients after hip hemiarthroplasty for femoral neck fracture and to evaluate the reconstruction of the femoral offset using standard neck angle stems. Material and methods: A consecutive series of 97 patients diagnosed with femoral neck fracture treated with a hip hemiprosthesis between 2017 and 2021 was identified and met the inclusion criteria. On preoperative images, the neck-shaft angle and the femoral offset on the healthy limb were measured. The femoral offset of the operated limb was measured on the postoperative X-rays. Results: There was a significant positive moderate correlation between neck-shaft angle and femoral offset change (r = 0.568, p < 0.0001). There was a statistically significant difference between femoral offset change and neck-shaft angle (24:52 vs. 14:7, p = 0.005). This means that in patients with coxa vara the change in femoral offset was more often < -5 mm. Less than half of operated patients had the femoral offset restored within a safe range (between -5 and 5 mm). Conclusions: Our study proved that it is sometimes hard to achieve femoral offset within a safe range while performing hip hemiarthroplasty in patients with coxa vara. The topic of using high offset stems in partial hip arthroplasty has not been thoroughly researched worldwide. However, taking into account the results of our study, during a hip hemiarthroplasty the usage of high offset stems for varus hips should be considered in order to improve the clinical outcome and improve patients' quality of life and functioning.

Introduction. Total knee replacement is the most efficient method of treating end-stage osteoarthritis of the knee joint. The surgery aims to relieve patients of pain, restore range of motion and improve patients’ quality lives. Prostheses design is still being modified and improved through cooperation between orthopaedic surgeons and engineers. Some of the most modern solutions aimed to fit native patients’ anatomy as much as possible are anatomic knee systems. Materials and methods. The literature was reviewed, and articles related to the subject were researched. Therefore, publications including keywords such as total knee replacement, anatomic implants and morphometric implants were searched in the PubMed, Cochrane and Google Scholar databases. All data was selected and verified individually. Analysis and synthesis of studies were prepared separately. Results. Many studies describe the advantages of anatomic prostheses over standard prostheses. Anatomical prostheses have a broader range of available sizes, thus providing better coverage of the distal end of the femur and the proximal tibia, allowing for the resection of less bone tissue, which is beneficial in the event of a possible need for a future revision of the endoprosthesis, enabling better selection of the tibial element rotation by better matching to the tibial plateau, which affects the alignment and patellar movement, and the structure of the trochlear geometry that also affects the patellar movement and reduces the risk of trochlear dysplasia. Conclusions. Anatomical implants enable better alignment of the prosthesis elements and the native femoral and tibial bone. Using these models makes it possible to obtain a greater range of motion and, consequently, improved functional outcomes compared to non-anatomical ones. It also enables less bone resection and better radiological outcomes.