A new classification of TKA periprosthetic femur fractures considering the implant type

Abstract

BackgroundThe treatment aims of periprosthetic fractures (PPF) of the distal femur are a gentle stabilization, an early load-bearing capacity and a rapid postoperative mobilization of the affected patients. For the therapy planning of PPF a standardized classification is necessary which leads to a clear and safe therapy recommendation. Despite different established classifications, there is none that includes the types of prosthesis used in the assessment. For this purpose, the objective of this work is to create a new more extensive fracture and implant-related classification of periprosthetic fractures of the distal femur based on available classifications which allows distinct therapeutic recommendations.MethodsIn a retrospective analysis all patients who were treated in the University Hospital Leipzig from 2010 to 2016 due to a distal femur fracture with total knee arthroplasty (TKA) were established. To create an implant-associated classification the cases were discussed in a panel of experienced orthopaedists and well-practiced traumatologists with a great knowledge in the field of endoprosthetics and fracture care. In this context, two experienced surgeons classified 55 consecutive fractures according to Su et al., Lewis and Rorabeck and by the new created classification. In this regard, the interobserver reliability was determined for two independent raters in terms of Cohen Kappa.ResultsOn the basis of the most widely recognized classifications of Su et al. as well as Lewis and Rorabeck, we established an implant-dependent classification for PPF of the distal femur. In accordance with the two stated classifications four fracture types were created and defined. Moreover, the four most frequent prosthesis types were integrated. Finally, a new classification with 16 subtypes was generated based on four types of fracture and four types of prosthesis. Considering all cases the presented implant-associated classification (κ = 0.74) showed a considerably higher interobserver reliability compared to the other classifications of Su et al. (κ = 0.39) as well as Lewis and Rorabeck (κ = 0.31). Excluding the cases which were only assessable by the new classification, it still shows a higher interobserver reliability (κ = 0.70) than the other ones (κ = 0.63 or κ = 0.45).ConclusionsThe new classification system for PPF of the distal femur following TKA considers fracture location and implant type. It is easy to use, shows agood interobserver reliability and allows conclusions to be drawn on treatment recommendations. Moreover, further studies on the evaluation of the classification are necessary and planned.

Periprosthetic tibial fractures in total knee arthroplasty – an outcome analysis of a challenging and underreported surgical issue

“…Periprosthetic fractures are a life-threatening condition for many of the predominantly elderly patients with a previous study reporting a one-year mortality rate between 11 to 44.8% [ 9 , 10 ]. Therefore, the main object is to achieve early mobilization with a good functionality to reduce mortality [ 11 ]. Further aims include restoration of leg axis, bone-implant union and a stable joint which is influenced by patients’ general condition as well as the type of TKA.…”

Megaprostheses and custom-made implants in complex cases of revision surgery after TKA

“…Nowadays, patients are exposed to a major risk of revision surgery due to trauma or septic/aseptic mobilization given the increase in both the number of first implant prosthesis and the earliness of the implant itself. The main points to be considered to deal with these complex cases are the type of the implant 5 and the patient's bone quality. In fact, revision implants are directly responsible for reduction of the bone stock.…”

“…These devices are a promising alternative that can restore joint function, with rapid recovery and allowing for limb salvage 1 . The indications for megaprosthesis implantation have been broadened to the treatment of selected non-neoplastic conditions of the hip and knee, all characterized by critical size bone defects such as acute trauma in severe bone loss and poor bone quality, post-traumatic failures and major bone loss in both aseptic and septic prosthetic revision, periprosthetic fractures with component mobilization, and poor bone stock condition and resistant non-unions despite multiple surgeries [2][3][4][5] . Massive bone loss can pose a significant challenge especially in revision knee arthroplasty (RKA) with distal femoral replacements that may allow for early mobilization and quicker return to function 1 .…”

The challenge of total knee arthroplasty periprosthetic fracture: a comprehensive review

“…TKAPF in the elderly should be considered a life-threatening condition, as underlined in studies reporting a one-year mortality between 11 to 44.8% 10,11 . Therefore, the objectivies of treatment should be similar to other fragility fractures: early mobilization and weight bearing in order to reduce the patient's morbidity and mortality 12 . The treatment of TKAPF presents a relevant complication rate.…”

“…The treatment of TKAPF presents a relevant complication rate. A review of 415 cases reported a nonunion rate of 9%, fixation failure in 4%, an infection rate of 3%, and revision surgery in 13% 12 . The choice of the most appropriate fixation device of TKAPF is a matter of debate, considering that locking plates and retrograde intramedullary are both associated with good outcomes in terms of fracture union and joint function 13 .…”