Adverse Events in the Treatment of Periprosthetic Fractures Around the Knee - a Clinical and Radiological Outcome Analysis. / Komplikationen in der Behandlung periprothetischer Frakturen bei einliegender Knietotalendoprothese ­ eine klinisch-radiologische Outcome-Analyse.

BACKGROUND: The incidence of periprosthetic fractures associated with total knee arthroplasty (PpFxK) has been reported to be 0.3 - 5.5%. 40% of all cases are related to revision TKA. The most common localisation is the distal femur. Classification is performed according to Rorabeck (RB). RB I - II fractures are usually treated with locked plating and retrograde intramedullary nailing, whereas RB III fractures are an indication for revision arthroplasty using a hinged endoprosthesis. PpFxK of the patella can be classified according to Goldberg and PpFxK of the proximal tibia can be grouped as in Felix. Interprosthetic fractures can be regarded as a special type of PpFx. Due to the increasing numbers of TKA being performed, increasing numbers of adverse events in arthroplasty can be expected. Adverse events in the treatment of PpFxK occur in up to 41% of patients according to the literature and revision is needed in approximately 29% of all cases. Risk factors are age, osteoporosis, infection, malalignment, osteolysis/loosening of the implant and status post revision. PATIENTS: A clinical and radiographic follow-up was performed with 50 patients (14 men, 36 women) treated for PpFxK of the femur, tibia and patella between 2011 and 2015 at the department of arthroplasty at a level 1 trauma center in Europe. RESULTS: The follow-up of all patients was 68%, with an average of 19.1 ± 14.6 (1 - 49) months between PpFxK and clinical follow-up. 16% of the patients were allocated for further treatment or revision surgery from other hospitals. The patients' median age was 78.0 ± 8.8 (55 - 94) years. Most patients were affected by several orthopaedic and internal medical comorbidities. PpFxK classified as RB II were the most common fractures (60%, n = 30). PpFxK usually occurred 5.0 ± 4.8 (0 - 20) years after index TKA (primary or revision TKA), mostly in patients with CR-retaining endoprosthesis, whereas PpFxK according to Felix occurred significantly earlier and mostly in hinged TKAs. Patients achieved on average a mean Oxford Knee Score of 31.1 ± 9.9 (14 - 46) points. The functional Knee Society Score (KSS) was 52.6 ± 24.4 (20 - 100) and the mean KSS was 58.7 ± 26.8 (0 - 99) points (n = 25). Radiographic evaluation of the RB I - II patients showed frontal and sagittal malalignment in 20.6% of all cases after reduction and plate fixation. The overall rate of surgical adverse events was 50%; 44% of all RB patients needed revision surgery. Adverse events comprised non-union, failure of osteosynthesis, infection, wound healing disorders and re-fractures in the RB II and the Felix subgroup. CONCLUSION: PpFxK are severe injuries and are associated with a high rate of adverse events related to treatment. Patients often have a complex background and a history of revision surgery or periprosthetic joint infection. The treatment of PpFxK should therefore take place at a centre with expertise in traumatology as well as in revision arthroplasty. Preoperative infection diagnostic testing as well as adequate imaging (X-rays and CT) are essential. We furthermore advise early evaluation of revision arthroplasty, especially in elderly patients suffering from PpFxK with insufficient bone quality around the TKA and closeness between fracture and TKA. In the case of plate fixation, it is important to give attention to correct reduction - to prevent non-union, loosening of the implant and failure of the osteosynthesis - as well as to consider double plating.

Origin of the anterior cruciate ligament and the surrounding osseous landmarks of the femur.

The aims of this study were to evaluate the discernibility of the LIR (lateral intercondylar ridge) and the LBR (lateral bifurcate ridge) and show their reliability in femoral tunnel placement in ACL (anterior cruciate ligament) reconstruction. Additionally, their position to the femoral axis, their course, and the ACL footprint were analyzed. For this study, 235 human femora were evaluated. Of these, 166 specimens originated from the Museum of Natural History (group A), and 69 were obtained from fixed cadavers at the Anatomic Institute (group B). The femoral footprint and the osseous landmarks were identified macroscopically and labeled in the photographs. A coordinate system was outlined, and the dimensions, position, and orientation of the femoral footprint of the ACL were measured. The LBR was found in 24.7% of the specimens in group A and in only 13.2% of the specimens in group B. The LIR was found in 97.9% and 85.3% of the specimens in groups A and B, respectively. The area of the ACL footprint was 127.21 ± 32.54 mm(2) in group A and 119.58 ± 34.84 mm(2) in group B. The shapes and angles of the osseous landmarks near the line of Blumensaat were highly variable. The LBR is an unreliable intraoperative landmark for arthroscopic ACL reconstruction due to its low incidence. Other anatomical structures, such as the LIR or the osteochondral border, may be more helpful and reliable landmarks to guide proper tunnel placement.