Keywords arthroplasty - arthroplasty, replacement, knee - infections - knee joint
Introduction
Epidemiological data show that between 6 and 12% of total knee arthroplasties (TKA)
evolve to failure, requiring revision surgery in the first 10 years.[1 ] Other recent studies have shown an increase in the number of revision surgeries
of TKA (RTKA) performed in recent years.[2 ]
[3 ]
[4 ]
[5 ] There was a 144% increase in the number of RTKA performed in Germany between 2004
and 2014.[6 ] It is estimated that, for the year 2050, in the same country, there will be an increase
of about 90% in the number of revision surgeries of knee arthroplasties.[4 ] In the United States, the increase in the number of such procedures was of 39% between
2006 and 2010.[7 ] And future estimates point to a continuous increase in the number of these surgeries
by the year 2030.[8 ]
The etiology for increasing the number of RTKAs is, in fact, multifactorial, being
influenced both by factors related to technical issues and evolution of implants and
instruments, as well as by factors related to patients.[9 ]
[10 ] An example of this, the wear of the polyethylene component was a frequent cause
of revision in the past; however, changes in the sterilization process of these components
culminated in a significant reduction in the number of revisions for this reason.[11 ]
[12 ]
[13 ] At the same time, the expansion of primary prosthesis indications, especially for
younger patients, and the higher incidence of obesity in the world population may,
at least partially, also justify potential changes in the failure patterns of modern
arthroplasties.[9 ]
[14 ]
[15 ] Meehan et al.[14 ] demonstrated that the risk of septic failure was 1.81 times higher in patients under
50 years of age when compared to patients older than 65 years. Similarly, among younger
patients, the risk of revision for aseptic failure was 4.7 times higher.[14 ]
Knee prosthesis revision surgeries are procedures of high complexity, performed in
a limited number of hospitals and, consequently, that require greater expenditure
of technical and economic resources.[16 ]
[17 ] Compliance with technical principles is essential to obtain satisfactory results
in this type of surgery.[18 ] Thus, preoperative planning, failure mode identification and adequate treatment
of bone defects are of fundamental importance for obtaining satisfactory and long-lasting
clinical results in this type of surgery.[18 ]
[19 ]
In this context, the identification of the cause of implant failure is significantly
important for planning and obtaining satisfactory results.[20 ] Several series have demonstrated changes in the causes of TKA failure over the years,
possibly related to evolutions in implant design, as well as instrumental improvements.[11 ]
[12 ] Thus, this study aims to identify the causes of RTKA in a reference center in Brazil.
Materials and Methods
This is a series of cases of patients undergoing RTKA at the Center for Specialized
Attention in Knee Surgery of Instituto Nacional de Traumatologia e Ortopedia (INTO)
Jamil Haddad, in the period between August and November 2019 (CAAE- 20309419.0.0000.5273.).
There was no age limit, no restriction on the gender of the participants.
During the study period, 88 arthroplasty revision surgeries were performed. One patient
underwent revision of the unicompartmental implant of the knee and was therefore excluded.
Seven surgeries were excluded from the analysis because it was the second revision
surgery. Thus, after the exclusion criteria, 80 surgeries (80 patients) were analyzed.
The mean age of the patients in the procedures was 69.6 years (standard deviation
(SD) = 9.85 years; variation = 29–87 years). Of these patients, 60.23% were female
and 39.77% were male. The mean body mass index (BMI) was 30.23 kg/m2 (SD = 5.92; variation = 18.20–42.46 kg/m2 ).
Arthroplasty review was defined as reoperation after performing primary TKA in which
it was necessary to add or replace one or more prosthetic components. Thus, patients
submitted to reoperations, however without the addition or replacement of one or more
primary prosthetic components, were excluded from the analysis. Patients submitted
to unicompartmental knee implant (UKI) revision surgery were also excluded from the
analysis, as well as patients submitted to the second revision surgery.
The following data were collected from medical records: age, gender, and BMI. Laboratory
tests with analysis of hemo-sedimentation velocity (HSV), C-reactive protein (CRP),
and D-dimer were performed in all patients on the day before surgery, as well as range
of motion measurement using a goniometer by the orthopedist in training in the knee
surgery improvement course at the institution. Radiographs of the knee at anteroposterior
incidences with bipodal, profile, and axial support in 30 degrees were performed on
the day before surgery. During surgery, synovial fluid was collected for the following
analyses: total leukocyte count, polymorphonuclear percentage, leukocyte esterase,
and culture in a blood culture vial. Six samples of bone tissue were also collected
for extended tissue culture for 14 days and 2 periprosthetic membrane samples for
histopathological examination.
In the surgical report, the following information were analyzed: surgical access performed,
implant system used, Anderson Orthopaedic Research Institute (AORI) classification
of bone loss, use of trabeculated metal cones and/or tissue bank grafts for the treatment
of defects.
Regarding the surgical access used, the surgery was performed by conventional medial
parapatellar access in 70 surgeries (87.5%). Extended access was performed in 10 surgeries
(12.5%), with tibia anterior tuberosity (TAT) osteotomy in 7 cases (8.75%), quadriceps
turndown in two cases (2.5%), and clipping of the thigh reskin (snip) in one patient
(1.25%).
Implants with two different systems—Legacy Constrained Condylar Knee (Zimmer Biomet,
Warsaw, IN, USA) or Legion Revision Knee (Smith & Nephew plc, London, UK)—were used
in 40 surgeries (50%). In 24 surgeries (30%), constrictor implants (Rotating Hinge
Knee – Zimmer Biomet) were used. Spacers were implanted in 14 patients (17.5%). In
2 patients (2.5%), only patellar implants were used.
Medical documentation of bone defects was incomplete in five surgeries. Thus, when
analyzing 75 patients, the presence of bone defects was identified in 70% of the patients.
The distribution and classification of bone failures are shown in [Table 1 ]. Tantalum metaphysary cones were necessary for the treatment of bone defects in
21 patients (26.25%). Of these, tissue bank grafting was also used in nine surgeries.
In all, the homologous graft was used in 13 patients (16.25%).
Table 1
Classification of defects
Tibia n (%)
Femur n (%)
Flawless
15 (20%)
16 (21.3%)
1
20 (26.7%)
15 (20%)
2a
19 (25.3%)
15 (20%)
2b
9 (12%)
8 (10.7%)
3
12 (16%)
21 (28%)
The cause of RTKA was defined by the surgeon responsible for the procedure based on
the following criteria: all patients were submitted to evaluation according to the
criteria of the 2018 International Consensus Meeting (ICM 2018).[21 ]
[22 ] The diagnosis of periprosthetic infection was made when at least one of the major
criteria was present, that is, the presence of a fistula communicating with the joint
or presence of the same pathogen in two or more cultures of periimplant tissues. The
diagnosis of periprosthetic infection using the lower criteria was confirmed when
the score of the sum of the criteria was greater than or equal to six when the parameters
of the tests recommended by the ICM 2018 were observed. In cases defined with aseptic
failures, the surgeon in charge, after analysis of the physical examination, imaging
and laboratory examinations defined the reason for failure between the following possible:
ligament instability (when presence of dislocation or subluxation of prosthetic components,
or when pathological ligament opening greater than 5 mm during physical examination,
or ligament laxity greater than 5 mm in varus or varus stress tests during physical
examination or ap radiographs of the knee with load), limitation of range of motion
(when less than 50 degrees associated with physical disability declared by the patient),
periprosthetic fracture, poor alignment, aseptic loosening, pain due to non-replacement
of patellar cartilage, polyethylene wear, fracture of implants, or insufficiency of
the extensor mechanism.
Results
Periprosthetic joint infection (PJI) was the main cause of RTKA, corresponding to
47.73% of cases. The aseptic loosening of one or more components represented the second
most frequent cause of failure, resulting in 35.23% of revisions. Limitation of the
range of motion represented the 3rd most frequent cause, accounting for 5.68% of surgeries. Instability was the 4th most frequent cause of failure, occurring in 4.55% of patients. The other causes
of revision were: periprosthetic fracture (3.41%), insufficiency due to rupture of
the extensor mechanism (2.27%), pain attributed to non-replacement of patellar cartilage
(1.14%) ([Fig. 1 ]).
Fig. 1 Distribution of the causes of failure of total knee arthroplasty. Causa da Cirurgia = Reason
for surgery, Infecção = Infection, Soltura Asséptica = Aseptic loosening, Instabilidade = Instability,
Dor em patela não substituída = Pain on non-replaced patella, Fratura periprotética = Peri-prosthetic
fracture, Lesão do mecanismo extensor = Extensive mechanism injury, Limitação da ADM
(artrofibrose) = ROM limitation (arthrofibrosis)
Discussion
The main finding of our study was to identify that the main cause of failure in our
series of primary TKAs was periprosthetic infection. Other reasons that led to the
need for revision were, in decreasing order, aseptic loosening, limitation of the
range of motion, and joint instability. Similarly, several recent studies have demonstrated
periprosthetic infection as the most frequent mechanism of failure of primary prostheses,
reaching 20 to 37.7% of surgeries.[2 ]
[23 ]
[24 ]
[25 ] In the study by Evangelopoulos et al.,[24 ] periprosthetic infection was the main mechanism of failure with an incidence of
26.3%. However, when analyzing only patients submitted to the second revision surgery,
the authors identified that the incidence of periprosthetic infection remained the
most frequent reason for TKA failure with approximately 50% of cases. We believe that
this high incidence of revisions due to septic failure observed in our study may have
been influenced, at least partially, by the fact that the surgeries were performed
in the COVID-19 pandemic period. In this scenario, in several months, only emergency
surgeries were performed, such as acute periprosthetic infections and, consequently,
subsequent increase in the demand for reimplantation after treatment of infection
in two times.
Aseptic loosening represented the 2nd most frequent reason for implant failure in our series, occurring in approximately
35% of cases. Similarly, Bozic et al.[7 ] demonstrated that periprosthetic infection and aseptic loosening were the two most
frequent reasons for TKA revision. When analyzing more than 60,000 primary surgeries,
the authors identified septic failure in 25.1% of patients and aseptic loosening in
16.7% of cases.[7 ] Our results are in agreement with those of Koh et al.[26 ] and Evangelopoulos et al.,[24 ] who demonstrated aseptic loosening as the 2nd main cause of review, affecting, respectively, 32.7% and 25% of the failures. Siqueira
et al.,[1 ] when analyzing the arthroplasty registry of five countries, identified aseptic loosening
as the first cause of revision, affecting 30% of surgeries. Several other studies
have also reported aseptic loosening as the main mechanism of TKA failure with incidence
ranging from 24 to 44%.[10 ]
[27 ]
[28 ] We identified that the incidence of aseptic loosening in our series is in accordance
with the literature, although it is not the main mode of failure of our implants.
The limitation of the range of motion represented, in our series, the third most common
indication for RTKA, with approximately 6% of surgeries. Similarly, in the study by
Le et al., arthrofibrosis was the third most frequent indication for review, although
the incidence presented corresponds to approximately three times that observed in
our study. Pietrzak et al. [11 ] studied only the aseptic causes of revision and identified joint stiffness as the
2nd leading cause of revision with an incidence of 27.5%. Meanwhile, Le[29 ] and Koh et al.[26 ] showed an incidence that only 2.5% of patients required TKA revision due to functional
limitation imposed by movement arc restriction. Such differences can be explained,
at least partially, by the various definitions of joint stiffness, as well as being
influenced by the functional demand and expectations of patients.[30 ]
[31 ]
[32 ] We should also observe that, in our series, we included only patients submitted
to revision of prosthetic components; thus, patients submitted to manipulation under
narcosis after TKA or even reoperation with joint release were not analyzed, which
could have modified the incidence if we analyzed reoperations after knee prosthesis.
In a study conducted in Brazil evaluating short-term complications (up to 1 year),
the authors identified that joint stiffness was the most frequent complication affecting
7.5% of patients undergoing primary knee arthroplasty.[33 ]
In our study, component instability represented the 4th cause of RTKA, with approximately 5% of surgeries. Other studies have demonstrated
an incidence of instability ranging from 18.7 to 30%, constituting the 2nd or 3rd most frequent reason for TKA review.[10 ]
[28 ]
[29 ] However, in the works of Kasahara et al.[27 ] and Koh et al.,[26 ] instability was identified in 9.3% and 6.5%, respectively. Post-TKA instability
is usually indicated as a cause of early failure, that is, in implants with less than
2 years of evolution.[6 ]
[11 ] Thus, the reduction in the number of elective primary surgeries performed during
the study period, due to the restrictions imposed by the COVID-19 pandemic, may justify,
at least partially, the limited number of revisions due to post-TKA instability. Another
potential explanation can be attributed to the waiting time for this type of surgery
in the Brazilian public health service. Thus, any initial cases of instability can
potentially evolve with loosening of the implants, thus hindering the primary diagnosis
of component instability.
Despite the importance of our series reporting the distribution of the different causes
of RTKA in the national scenario, our study has significant limitations. We believe
that restrictions on elective surgeries imposed during part of the COVID-19 pandemic
period may influence the incidence of some modes of failure, such as suspension of
elective aseptic revisions in certain periods. Another important limitation refers
to the retrospective nature of our analysis. Thus, several patients submitted to revision
surgery had been operated on primarily in other hospitals. Thus, we had no control
over the evolution time from the implantation of the components to the occurrence
of failure requiring revision surgery, nor did we perform analyses of the different
systems of primary prostheses implanted. Schroer et al.[10 ] indicate that 35.3% of knee arthroplasties fail in the first 2 years after implantation,
being more often related to factors influenced by the surgeon than by the performance
of implants. However, we understand that such information is of high relevance for
the planning of the Brazilian health system in view of the increase in the number
of cases of RTKA, given, the impacts regarding the need for hospital beds, financial
resources, and technical training of the teams. Similarly, we believe that the high
number of revision surgeries performed due to septic failure observed in our series
alerts us to the need to expand the measures to prevent these serious complications.
Therefore, we believe that the adoption of preventive measures of postoperative infection,
such as: optimization of preoperative clinical conditions, adoption of risk stratification
scores and investigation of patients colonized by Methicillin-resistant Sthapylococcus aureus may impact on the reduction of the number of RTKA surgeries performed in our hospital.
Conclusions
We identified periprosthetic joint infection as the most frequent cause of RTKA. The
other TKA failure mechanisms were, in decreasing order: aseptic loosening, limitation
of the range of motion, and instability. Periprosthetic fracture and extensor mechanism
insufficiency were less frequent causes of primary prosthesis revision in our series.
