As the number of individuals taking primay or revision TKA is increasing, the relevant complications are also at increase. There are many causes of periprosthetic fracture after knee arthroplasty, which are mainly divided into patient factors such as age, female, trauma, aggressive activity, chronic use of steroids/corticoid therapy, rheumatoid arthritis and other risk factors is surgical factors such as excessive anterior femoral notching, forceful manipulation. According to an estimate, the risk of periprosthetic knee fracture ranges from 1.1–2.1% for primary knee arthroplasty, whereas, for revision TKA it has range of 0.7–1.5% (17). Internal fixation is widely used to address acute periprosthetic knee fractures, which renders advantage over non-operative techniques. Anyhow, various factors make operative techniques challenging and perplexing for surgeon (18). These factors include implant types, fracture displacement, amount and quality of bone available, postion, and fixation (19).
In order to avoid loss of mobility in patients with periprosthetic fractures, timely fracture union is important. The previous researh works have achieved this goal with the use of various conventional plating techniques (20). On the other hand, others have addressed to perplexities of salvage procedures in case of implant failure, non-union or mal-union. In a study performed by Deshmukh et al (21), two out of thirty femoral cases showed delayed union had were addressed through revision fixation and bone grafting. The study of Abbas and Morgan-Jones (22) showed higher levels of failure due to internal fixation and open reduction. Majority of the patients required repeated open reduction, and revision TKA. The work of Horneff et al (23) utilized supplemental strut grafting to the failed fixations and claimed good results in majority of the cases. Previous research works have pointed out towards various complications associated with fracture union (24). These complications are addressed with the help of different modern techniques of locked plating. However, the success rate may vary in accordance with the treatment strategies adopted to counter with the complications of failed primary treatment (25). Many factors exists that influence the revision fracture fixation. They may include secondary implant loosening, loss of bone stock and impaired vascularity (26). The fixation and stability of revision arthroplasty also get effected by loss of metaphyseal bone. To address this issue, distal femoral arthroplasty has widely been used by many researchers, especially in the low demand subgroup of individuals (27). Anyhow, many complications are associated with this method, when used to counter primary treatment failure (28).
The revision TKA is a conventional method used for periprosthetic fractures. Indications for the technique include component malposition, component loosening, instability, loss of bone stock and wear (29). Despite its importance, only few research works have elaboraated use of reivion TKA for managing mal-union or non-union of periprosthetic fractures (30). A previous study reported successful treatment of femoral non-unions with the helps of bone grafting and long stem primary knee arthroplasty (31). However, the literature shows varying results for revision arthroplasty, when used to address failed primary fixation or non-union of periprosthethic knee fractures.
The incidence of fracture in patients over 70 years old was 1.6 times higher than that in young patients, while the incidence in female patients was higher than that in male patients. The average age of this group was 70 years old. There were 11 female patients, accounting for 52.4% of all patients. This was consistent with the literature. The main reasons are the decline of muscle strength, poor compensatory ability of cardiopulmonary function, weakening of patient’s activity, prone to falls, sprains and other accidents. Low-energy injury can lead to serious periprosthetic fracture of knee joint. In this group, 2 patients had periprosthetic fracture of distal femur during functional exercise after operation. Excess anterior femoral notching in knee arthroplasty weakened the strength of anterior and posterior femoral cortex. It should be avoided as far as possible during operation. Therefore, the causes of periprosthetic fracture of distal femur after knee arthroplasty are various. Patients often have multiple risk factors for such complications. In order to avoid the occurrence of fracture, it is necessary to prevent from the internal and external causes of patients, so as to reduce the pain of patients. According to the patient's bone condition, fracture type and stability of the prosthesis, the treatment of periprosthetic fracture of after knee arthroplasty includes conservative treatment, mainly for patients with no displacement of fracture or absolute contraindication of operation; open reduction and internal fixation includes locking plate and intramedullary nail fixation, mainly for patients without loosening of prosthesis. Patients with enough space for fixation at the fracture end but revision knee arthroplasty is mainly used for patients with prosthesis loosening and comminuted fracture without possibility of internal fixation. A large number of literatures have described the treatment of open reduction and internal fixation, including locking compression plate and retrograde intramedullary nail fixation. For patients with good bone prosthesis stability, according to the type of fracture, there is no significant difference in the time of bed rest, complications and joint function recovery. However, there are nonunions and deformities in both methods. For elderly patients, in order to avoid the complications caused by bed rest and the risk of secondary operation of nonunion and malunion, many surgeons have proposed revision of knee joint or special prosthesis for periprosthetic knee fractures in recent years, which can carry out early weight-bearing activities, retain knee joint function, quick recovery and improve patients' quality of life. In this group of 21 cases, we used knee revision surgery, see (Figure-2 & 3) instead of using custom-made distal femur prosthesis and rotating hinge knee prosthesis, the authors of the literature used constrained condylar prosthesis. During the operation the fracture end was fixed with extension rod, similar to the effect of intramedullary nail, which shortened the operation time and allowed the patients to move early and perform functional exercises. This method can reduce the complications and mortality of patients especially for elderly patients with severe comminuted periprosthetic fracture with osteoporosis.
In the present research work, all individuals showed pain free mobility at last follow-up visit. Moreover, improvement in knee score and functional score was observed along with knee range of motion. These findings indicate the benfits and applicability of revision TKA. The use of revision TKA, as a reconstruction solution for the issues of mal-union and non-union of prosthetic knee fractures, is highly recommended. The problems of alignment, stability and bone loss can be well addressed through adequate use of constraint levels, intramedullary stems and metaphyseal sleeves.