A case-control study of spontaneous patellar fractures following primary total knee replacement

Abstract

Peri-prosthetic patellar fracture following resurfacing as part of total knee replacement (TKR) is an infrequent yet challenging complication. This case-control study was performed to identify clinical, radiological and surgical factors that increase the risk of developing a spontaneous patellar fracture after TKR. Patellar fractures were identified in 74 patients (88 knees) from a series of 7866 consecutive TKRs conducted between 1998 and 2009. After excluding those with a previous history of extensor mechanism realignment or a clear traumatic event, a metal-backed patella, any uncemented component or subsequent infection, the remaining 64 fractures were compared with a matched group of TKRs with an excellent outcome defined by the Knee Society score. The mean age of patients with a fracture was 70 years (51 to 81) at the time of TKR. Patellar fractures were detected at a mean of 13.4 months (2 to 84) after surgery. The incidence of patellar fracture was found to be strongly associated with the number of previous knee operations, greater pre-operative mechanical malalignment, smaller post-operative patellar tendon length, thinner post-resection patellar thickness, and a lower post-operative Insall-Salvati ratio. An understanding of the risk factors associated with spontaneous patellar fracture following TKR provides a valuable insight into prevention of this challenging complication.

Periprosthetic Fractures after Total Knee Arthroplasty

“…Most such fractures are associated with a stable implant and intact extensor mechanism, 19 and can be managed with immobilisation in a cylindrical cast.…”

“…16 However, in another study 30% of TKAs had a notched femur, but only 2 periprosthetic fractures occurred (both in femurs without notching). 17 The most common risk factor for periprosthetic patellar fractures after TKA is excessive patellar resection, followed by mal-alignment, 18 a shorter patellar tendon, 19 obesity, 20 and excessive flexion of knee. 21 Excessive lateral release has a deleterious effect on patellar blood supply, which can lead to fractures.…”

“…13 Periprosthetic patellar fractures are frequently asymptomatic, and the diagnosis is usually made during routine radiological examination. 18,19 Treatment goals are to achieve painless and stable knees with excellent alignment and range of motion. Conservative management (immobilisation in a brace or cast) is recommended for non-displaced fractures.…”

Kniegelenksnahe Frakturen bei Knie-TEP

“…Die meisten periprothetischen Patellafrakturen entstehen im Rahmen eines geringgradigen Traumas, Sturz auf das Knie oder exzentrischer Quadrizepskontraktur [2]. Viele werden auch spontan beobachtet [39].…”

Management of Periprosthetic Distal Femoral Fracture After Total Knee Arthroplasty Using Minimally Invasive Plate Osteosynthesis: A Case Report

“…[1,2] Most of the fractures around the TKA prosthesis occur in the supracondylar region of the femur although other regions such as patella and tibia have been reported. [3,4] In the past, these fractures have been treated by various methods such as open reduction and plate fixation and intramedullary nailing while many others were treated conservatively. However, they were associated with complications such as pain, stiffness, infection and delayed union.…”