Keywords osteoarthritis, knee - magnetic resonance imaging - clinical protocols
Introduction
Osteoarthritis (OA) is a chronic degenerative condition. It is considered a public
health problem because it is the most prevalent joint disease in the world, and the
single most common cause of disability in people older than 18 years of age. It mostly
involves the knee joint, especially in patients aged > 50 years, currently affecting
around 250 million people on the planet.[1 ]
In Brazil, the rapid aging of the population and the epidemic increase in obesity
is expected to result in an exponential growth in the number of patients with suspected
and diagnosed knee OA in the coming years.[2 ]
The diagnosis of OA is usually based on history, clinical examination, and x-rays.
Radiography is the most used imaging method because it is cheap, widely available
and validated; in addition, it facilitates the classification of disease severity.
Other subsidiary exams, such as magnetic resonance imaging (MRI), may be important
in specific situations.
The MRI is especially useful in confirming a suspected diagnosis when the clinical
and radiographic findings are divergent or doubtful. In addition to being a non-invasive
method to obtain multiplanar images, it presents high definition, sensitivity, and
specificity.[3 ]
The choice of the most appropriate test accelerates diagnosis, increasing the likelihood
of a successful treatment; moreover, it avoids unnecessary expenses for the healthcare
system.[4 ]
However, healthcare expenses are a complex issue, since human well-being and lives
are on the line.[5 ] Thus, the discussion must not focus only on finances, but on efforts to provide
services with maximum efficiency and quality.[6 ]
Therefore, the development of an easy-to-use protocol based on the medical literature
to guide MRI requests for elderly patients with suspected knee OA is critical, as
it will not only improve the therapeutic approach to the patient but also reduce unnecessary
MRI requests, resulting in a better distribution and use of the available healthcare
resources.[7 ]
The present study aims to develop an evidence-based protocol to guide MRI-scan requests
in elderly patients with suspected knee OA and to evaluate its effectiveness after
implementation.
Materials and Methods
The present study evaluated 22,654 outpatient visits to the orthopedics service at
Hospital Sancta Maggiore, in the city of São Paulo, Brazil. The patients were examined
by knee-specialist orthopedists from January 1st to December 31st, 2018. After the
application of the inclusion and exclusion criteria, a total of 826 patients with
suspected knee OA underwent an MRI scan.
Institutional Protocol
The methodological strategy consisted in a query on the PubMed and SciELO databases
to identify studies on the diagnosis od OA and knee pain published over the previous
5 years. The query was directed to articles written in Portuguese or English, with
full public electronic access, including the following keywords: knee osteoarthritis,
knee pain, diagnosis, MRI, and magnetic resonance.
The publications of interest were initially selected based on title and abstract;
the relevant publications cited by the chosen articles were also analyzed.
Editorials and letters to the editor were not included. After the final selection
and full-text reading of all papers, the following specific protocol for the request
of knee MRIs in elderly patients with diagnosed or suspected knee OA was proposed
and updated.
The criteria for MRI request in patients aged > 60 years with chronic knee pain (>
6 months) and suspected/diagnosed knee OA were the following:
Previous anteroposterior (AP) and lateral (L) radiographs of the knee under load;
History of acute knee trauma/sprain;
Signs and symptoms of joint block;
Positive meniscal tests with no diffuse knee pain;
Acute/sudden knee pain with no trauma (suspected knee osteonecrosis);
Pain disproportionate to the radiographic findings;
Suspected fragility fracture in patients with osteoporosis; and
Suspected knee tumor.
Patient Selection
The inclusion criteria were the following: 1) age > 60 years; 2) suspicion or diagnosis
of knee OA; and 3) attendance at the institutional orthopedics outpatient clinic in
2018. Ethe exclusion criteria were the following: 1) cases of secondary osteoarthritis;
2) patients with systemic inflammatory diseases; 3) MRI requested for different purposes,
such as medical reports and work-related reports; and 4) medical records with insufficient
information.
Protocol Implementation and Evaluation
The institutional protocol was developed during the first semester of 2018. After
its conclusion and review, the protocol was massively disseminated in the various
contact channels among institutional knee-specialist orthopedists (e-mail, intranet,
WhatsApp) during the second semester of 2018.
Thus, the control group was defined as patients cared for in the first semester of
2018, before the implementation of the institutional protocol, and the study group
was composed of patients cared for during the second semester of 2018, after the standardization
of MRI requests for suspected knee OA.
Clinical Analysis
The factors included in the clinical analysis were as follows: age, gender, laterality,
number of MRIs requested in each semester, number of visits in each group, existence
of prior requests (in the previous twelve months) for knee radiographs and changes
in diagnosis or treatment after MRI analysis.
Statistical Analysis
The statistical analysis was performed using the stats package of the R software (R
Foundation for Statistical Computing, Vienna, Austria).[8 ] The nominal variables were described as proportions, and the continuous variables
were described as means and standard deviations. The Shapiro test[9 ] assessed the distribution of the continuous variables in each group. The Student
t and Mann-Whitney U tests were applied for parametric and non-parametric measurements.
The Pearson chi-square test[10 ] was used to compare the categorical variables between the groups. Statistical significance
was set at p ≤ 0.05.
Results
The total sample consisted of 22,654 medical visits with knee-specialist orthopedists,
with 10,869 visits for the control group (first semester of 2018) and 11,785 for the
study group (second semester of 2018); the number of visits was similar for both time
periods. On average, the patients were 69.3 years old. [Figure 1 ] shows the age distribution of the total sample.
Fig. 1 Age density of the total sample.
[Table 1 ] shows epidemiological data from both groups.
Table 1
Characteristic
Before the protocol
After the protocol
p -value
Age
69.3 (7.6)*
69.4 (7.9)*
0.62
Gender
Female = 73.7%
Male = 26.3%
Female = 69.1%
Male = 30.9%
0.34
Dominant side
Right = 50.5%
Left = 49.5%
Right = 44.7%
Left = 55.3%
0.22
Was a radiograph requested before the magnetic resonance imaging scan?
Yes = 23.9%
No = 76.1%
Yes = 47.1%
No = 52.9%
p < 0.001
Did the magnetic resonance imaging scan change the conduct or diagnosis?
Yes = 13.8%
No = 86.2%
Yes = 11.2%
No = 88.8%
0.30
There was a 47.5% reduction in the number of MRI requests by orthopedists specialized
in knee surgery after the implementation of the institutional protocol, from 559 (67.7%)
requests during the first semester of 2018 to 267 (32.3%) requests in the second semester
of 2018, as shown in [Figure 2 ].
Fig. 2 Number of magnetic resonance imaging (MRI) scans requested for the study and control
groups.
When analyzing the number of MRI scans in each group according to the number of visits,
there were 2 MRI scans for every 100 visits after the implementation of the protocol.
For the control group, that is, the patients examined before the protocol was implemented,
there were 5 MRI requests for every 100 visits, totaling an approximate reduction
of 3 scans for every 100 visits.
Protocol implementation increased the number of radiographs requested prior to MRI,
with an increase of almost 96% in the total number of requests. Previous radiographs
were requested for 23.9% of the control group, and for 47.1% of the study group ([Figure 3 ]), with a statistically significant difference (p < 0.001).
Fig. 3 Number of radiographs requested prior to the MRI requests for the study and control
groups.
The analysis of the MRI changed treatment or diagnosis for 11.2% of the patients from
the study group, and for 13.8% of the control group, with no significant difference
between the groups (p = 0.30).
Discussion
The main results of the present study were the development of an institutional protocol,
based on the current literature, for the request of knee MRIs in elderly patients
with suspected knee OA and the subsequent confirmation of its effectiveness after
implementation among the team of knee-specialist orthopedists.
There was a 52% reduction in the number of knee MRI requests after the implementation
of the institutional protocol. This represented a decrease of 292 scans during the
second semester of 2018, corresponding to 49 fewer knee MRI scans per month. These
vacancies could then be filled by more urgent, critical MRI requests, reducing the
waiting time and list for these tests. Spence et al.[7 ] found similar results, with a 71% reduction in inappropriate knee MRI requests in
OA patients after protocol implementation. This reduction resulted in 45 vacancies
per month for more urgent tests.
Kandiah et al.[11 ] demonstrated a 21% reduction in knee, shoulder and hip MRI requests after the development
and implementation of a protocol to request these tests for patients over 55 years
old. These results were inferior to those observed in other studies, possibly due
to the joint analysis of MRI requests for several joints, including those of the shoulder
and hip.
The differences from previous studies can also be related to the doctors requesting
these tests, since other authors[5 ]
[12 ] have demonstrated differences in the request patterns from general orthopedists,
specialized orthopedists, and primary care physicians. The protocol developed in the
present study was only implemented among knee specialists.
Another important finding of the present study was the 96% increase in the number
of requests for knee radiographs after the implementation of the institutional protocol.
This change resulted in a reduction from 76% to 52% in the number of patients with
diagnostic suspicion of OA who underwent a knee MRI with no prior radiographs. Despite
this reduction, the numbers still show a low adherence to the current protocol, since
one criterium was not met by these requests.
Gonzalez et al.[13 ] also observed a low adherence to the protocol (57%) by primary care physicians in
a study with patients with non-acute knee pain with an average age of 53 years. In
a study evaluating limb MRI requests at the emergency room, Glover et al.[14 ] demonstrated that the most common reason for inappropriate MRI requests was the
failure to perform previous radiographs. In a study with elderly patients, Parent
et al.[15 ] observed that only 38% of patients undergoing knee MRI scans had been submitted
to knee radiographs in the previous 24 months.
In the present study, treatment was not altered in approximately 86% of the patients
after the analysis of the MRI scans requested by the doctor. Another similar study[13 ] showed that approximately 20% of the patients had their clinical therapy altered
by knee MRI findings. Lehnert et al.[16 ] also demonstrated that 76% of the general MRI scans requested by general practitioners
presented normal findings and did not change the treatment of the patients.
The development of institutional protocols to guide medical practices is essential
for standardization and correct decision making. In addition, these guidelines provide
better use of finite, scarce healthcare financial resources. Parker et al.[17 ] estimated a cost of 2 billion dollars in 2020 alone with musculoskeletal MRI requests
for Medicare beneficiaries in the United States. Thus, the emergence and implementation
of protocols in this area are vital for better financial control, avoiding waste.
Although the knee OA classification has been described by Kellgren-Lawrence,[18 ] it remains current for the diagnosis and management of the condition despite some
divergences between radiological and clinical findings. The MRI is more sensitive
and specific compared to radiography, and it can be used in certain situations, because
the scan does not alter the diagnosis and radiographic classification.
The present study has some limitations. Since it was carried out in a single institution,
with its own orthopedics team and ease of internal communication, it is difficult
to generalize the findings to other services. In addition, the protocol was implemented
only for knee-specialist physicians; therefore, there is no comparison with general
practitioners and primary care physicians. The reasons for non-adherence and follow-up
of the developed protocol by the doctors were not evaluated.
Conclusion
After developing and implementing an institutional protocol for knee MRI requests
in elderly patients with suspected knee OA, there was a 47.5% reduction in the number
of requests, and a 96% increase in the number of initial requests for knee radiograph.
In addition, most (89%) patients did not have their treatment changed after the analysis
of the findings from the MRI scans requested by the doctors.
