Abstract
Background
As the number of primary or revision TKA with stem extension cases are growing simultaneously, the number of periprosthetic fracture in these cases has also increased accordingly. However, there have been few reports on the classification and treatment of periprosthetic fracture following stemmed TKA and lack of information about the treatment outcome. The purposes of this study were 1) to demonstrate classification and management of periprosthetic fractures after stemmed TKA and 2) to report treatment outcome after the periprosthetic fractures.
Materials and Methods
This retrospective study included 17 knees (15 patients) with an average age of 69.7 years. All cases were revision TKA cases, and there were 13 female and 2 male patients. The patients were treated nonoperatively or underwent operation by orthopedic principle. The period of union was evaluated by confirming the formation of callus crossing fragments in radiographs. We reviewed the complications and functional outcomes after treatment of periprosthetic fracture following revision TKA by assessing FF, FC and scoring WOMAC and KSS.
Results
The classification of periprosthetic fractures of stemmed TKA was based on location of fracture and stability of implant. They were classified as follows: type I, metaphyseal fracture without loosening of implant [Fig. 1]; type II, diaphyseal fracture adjacent to stem without loosening of implant [Fig. 2]; type III, diaphyseal fracture away from stem without loosening of implant [Fig. 3]; and type IV, metaphyseal or diaphyseal fracture with loosening of implant [Fig. 4]. There were 1 case of type I, 9 cases of type II, 4 cases of type III and 3 cases of type IV fractures. The mean time for gaining radiographic union of type I was 3.3 month; type II was 4.4 month; type III was 4.6 month; and type IV was 3.9 month. Most of the metaphyseal fractures were comminuted and all cases of loosening of the femoral implant were found in the metaphyseal fractures. Nine periprosthetic fractures were fixed using locking plate (single locking plate : 4 cases, dual locking plate : 5 cases). The bone union period is much shorter in patients with dual plate fixation than single plate only. Range of motion, WOMAC and KSS were not significantly different between before fracture and after management of fracture. Complications included 1 metal failure, 2 loosening of implant and 1 postoperative infection.
Conclusions
Metaphyseal fractures probably cause the collateral ligament insufficiency, and loosen the implant. Therefore, rotating hinge prosthesis should be used to stabilize the ligament of knee joint. Also, Revision TKA with longer stem should be considered if the stability of implant is not sure. When we underwent operation using plate fixation, dual plating provided better stability of fracture and shortened the union period than single plating. However, we need to approach individually depending on the patient, such as using cerclage wire, bone graft and so on. This study will help to establish appropriate treatment options according to each classification.
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