RESUMEN
BACKGROUND: Posterior-stabilized (PS)-total knee arthroplasty (TKA) arose as an alternative to cruciate-retaining (CR)-TKA in the 1970s. Since then, it has become a popularly utilized TKA design with outcomes comparable to CR-TKA. The post-cam mechanism is unique to PS-TKA as it substitutes the function of the posterior cruciate ligament (PCL). The study aimed to understand the kinematic and laxity changes in PS-TKA with under- and overstuffing of the tibiofemoral joint space with the polyethylene (PE) insert. METHODS: This study employed a hybrid computational-experimental joint motion simulation on a VIVO 6 degrees of freedom (6-DoF) joint motion simulator (AMTI, Watertown, MA, USA). Physical prototypes of a virtually-performed TKA in mechanical alignment (MA) and kinematic alignment (KA) based on cadaveric CT scans and a virtual ligament model were utilized. The reference, understuffed (down 2 mm) and overstuffed (up 2 mm) joint spaces were simulated, neutral flexion and laxity testing loads and motions were performed for each configuration. RESULTS: The PE insert thickness influenced post-cam engagement, which occurred after 60º in the overstuffed configurations, after 60º-75º in the reference configurations and after 75º in the understuffed configurations. The understuffed configurations, compared to the reference configurations, resulted in a mean 2.0º (28%) and 2.0º (31%) increase in the coronal laxity in MA and KA respectively. The overstuffed configurations, compared to the reference configuration, resulted in an increase in the mean joint compressive forces (JCFs) by 73 N (61%) and 77 N (62%) in MA and KA models, respectively. CONCLUSIONS: The under- and overstuffing in PS-TKA alter the kinematics with variable effects. Understuffing decreases the stability, JCFs and inverse with overstuffing. Subtle changes in the PE insert thickness alter the post-cam mechanics.
RESUMEN
Elderly hip fracture patients are at risk of stress-related gastric mucosal damage, and upper gastrointestinal bleeding is one of the underrecognized but devastating complications.Proton pump inhibitors (PPIs) offer effective prophylaxis against stress-related gastric mucosal damage.Systematic analysis of the literature revealed numerous articles on PPIs and hip fractures, but only three articles dedicated to the analysis of prophylactic use of PPIs in patients with a hip fracture.There is significant reduction in upper gastrointestinal bleeding following PPI prophylaxis and reduced 90-day mortality in elderly hip fracture patients on prophylaxis.PPIs are generally safe, cost-effective and based on available evidence. Their prophylactic use is justifiable in elderly patients with hip fractures.We suggest that PPIs be prescribed routinely peri-operatively in elderly hip fracture patients. Further level-one studies on the subject will allow for firmer recommendations. Cite this article: EFORT Open Rev 2021;6:686-691. DOI: 10.1302/2058-5241.6.200053.