Management of periprosthetic fractures around the knee
Periprosthetic fracture around the knee is the most common one among all periprosthetic fractures, and supracondylar fracture of the femur is the most common type around the knee. Unfortunately, the one-year mortality rate after a periprosthetic fracture is very high, reaching 25%. While osteoporotic fracture fixation is already difficult, the management of these fractures remains a challenging problem because of associated osteoporosis, devascularization of the bone from the previous arthroplasty surgery, and medullary canal filling prosthesis. The treatment aim is rapid mobilization of the patient with a friendly soft tissue surgery, good reduction, and stable fixation. The objective of this article is to review the treatment principles of this type of fractures.
Periprosthetic fractures around the knee today; It is increasing gradually due to the prolongation of life expectancy, the increase in arthroplasty surgeries and the errors during the application of the prosthesis. 70% of all periprosthetic fractures are fractures around the knee and are more common in men. Open fractures and multiple fractures are very rare and are usually encountered after domestic falls. The most common fracture after total knee arthroplasty (TKA) is supracondylar femur fracture with a rate of 0.6-2.5%. Tibia fractures are observed with a rate of 0.4%, while 0.1% of fractures occur intraoperatively.[1] According to Streubel et al., mortality in the first 30 days after these fractures is 6%, six-month mortality is 18%, and unfortunately the mortality in the first year is 25%.[2] Many researchers are working on the causes and solutions of periprosthetic fractures. According to Petersen et al., after TKA, stress shielding occurs in the distal femur, especially on the anterior surface, and bone mineral density decreases by 19–44% in the first year[3]. increases significantly. According to Figgie et al., the risk of fracture in the first eight years is around 40% in patients who underwent anterior femoral notching.[4] It is known that the notched femur can fracture with 18% less force in bending and 38% less force in torsion compared to the normal femur. This risk increases as the notch gets larger, deeper and closer to the prosthesis. Among the risk factors for periprosthetic fracture after TKA; osteopenia (age, cortisone, RA…), stress points (drill holes, local osteolysis, stiff knee, tibial tubercle osteotomy…), neurological disorders (gait disturbance, convulsions, phenytoin…), advanced varus deformity, posterior stabilized femoral component designs ( risk of intraoperative fracture when removing more bone from the intercondylar region) and loosening of the components, mostly on the tibial side.
Technical errors that increase the risk of fracture are; Poor insertion of the intramedullary guide (ant penetration), bad bone cuts, too strong hammering of the components, eccentric placement of the trials, tibial tubercle osteotomy, posterior stable prostheses and excessive resection of the patella. The treatment of these fractures also presents some additional difficulties compared to other fractures and may be negatively affected by some factors. Among them; Presence of osteoporosis/osteolysis in the patient, the existing implants can block fixation, ischemia due to previous surgeries, delay in fracture healing due to deperiostization and cementation, and the presence of accompanying bone defects (loose implant). Our treatment goals are to provide anatomical alignment, maintain or provide adequate bone stock, create a stable prosthesis, early mobilization of the patient, union of the fracture and at least reinstatement of the patient. As a treatment strategy for all periprosthetic fractures: • If the prosthesis is stable: fixation • If the prosthesis is unstable: fixation + revision • If the prosthesis is unstable + poor bone quality: – massive allograft + composite prosthesis or – mega-prosthesis.
