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MRI accuracy in diagnosing knee
pain |
We like to
comment on medical literature so that you as our loyal
readers can know that everything you read must be taken in
the proper context. There was a recent article from Science
Daily, June 2008 issue entitled Meniscal damage and
the development of persistent knee pain.
Marked by
cartilage and bone
degradation, progressive knee
osteoarthritis
(OA) is believed to result in part from a combination of
several local mechanical factors. Lack of joint stability,
poor joint alignment and injuries to the disks of
meniscal tissue that
cushion the knee all affect load distribution and the toll
to the vulnerable OA knee. However, in studies of knee OA
progression, either meniscal damage or malalignment has been
considered, but not both together, and no studies have
included joint laxity.
Unlike radiographs, magnetic
resonance imaging (MRI)
can distinguish
articular cartilage
(see
also
Articular
Cartilage Growth)
from meniscal tissue and detect the impact of specific
factors on OA progression. Almost all studies of knee OA
progression with MRI outcomes define cartilage loss with
qualitative cartilage assessments. For a clearer picture of
the role of various mechanical factors in knee OA,
researchers at Northwestern University and Salzburg
Univeristy applied quantitative measures of cartilage
loss—decreases in cartilage volume and thickness and an
increase in bare bone area—as well as cartilage integrity
score.
Their results indicate three
factors that independently predict cartilage loss with a
direct impact on knee OA: medial meniscal damage, lateral
meniscal damage, and varus, or bow-legged, malalignment of
the knee joint. Notably, quantitative cartilage loss outcome
measures were more sensitive in revealing these
relationships than previously applied qualitative
approaches.
The study’s participants, 153
women and men with radiographic evidence of knee OA, were
recruited from local senior citizens groups and the registry
of the Beuhler Center on Aging at Northwestern University.
The mean age was 66 years and the mean BMI was 30. None of
the subjects had a history of
Rheumatoid Arthritis,
gout,
joint infection, or meniscectomy. A total of 251
osteoarthritic knees were thoroughly scanned with MRI and
rigorously studied. Meniscal damage and meniscal extrusion
were graded using the Whole-Organ MRI Score (WORMS).
Varus-valgus alignment and medial-lateral
laxity were also
measured.
Focusing separately on
medial and
lateral segments of tibial and weightbearing femur cartilage
of the knee joint, cartilage volume, percentage of
subchondral bone covered with cartilage, exposed subchondral
bone area, and the average thickness of cartilage were
measured using specialized software. Cartilage integrity was
also scored. Two years later, the entire process was
repeated. Odds ratios were determined for each of the four
mechanical factors using logistic regression analysis,
adjusting for age, sex, BMI, and the other factors.
Medial meniscal damage
significantly increased the likelihood of cartilage volume
loss, cartilage thickness decrease, and denuded bone
increase in both the medial tibial and the medial
weightbearing femoral segments. Similarly, lateral meniscal
damage predicted quantitative cartilage loss in both the
lateral tibial and the lateral weightbearing femoral
segments. Varus malalignment was strongly associated with
cartilage loss from each medial surface; valgus (knock-knee)
malalignment was not associated with lateral surface loss.
Meniscal extrusion and joint laxity had inconsistent
effects. Using the qualitative cartilage assessment,
however, no significant relationship with outcome was
detected for either meniscal damage or malalignment.
Dr. Leena Sharma, the study’s
leading author and spokesperson, commented “It is important
to note that local factors, such as those examined in this
study, may participate in vicious circles with the worsening
of knee OA. Whenever along the OA disease timeline a local
impairment develops, it may contribute to subsequent OA
progression and cartilage loss, especially given the
vulnerable milieu of the already damaged OA knee.
Ultimately, strategies that interrupt these vicious circles
may be especially powerful."
Sharma, L. et al. Relationship of Meniscal Damage,
Meniscal Extrusion, Malalignment, and Joint Laxity to
Subsequent Cartilage Loss in Osteoarthritis Knees.
Arthritis & Rheumatism, June 2008; 58:6 pp.
1716-1726
Wiley-Blackwell (2008, June 2). Meniscal Damage And Joint
Malalignment Predictors Of Cartilage Loss. ScienceDaily.
Retrieved August 28, 2008, from
http://www.sciencedaily.com/releases/2008/06/080602160758.htm
Caring Medical’s
Opinion:
Ross Hauser, MD
“Doctor my MRI
showed…” Oh, I hate those words. People are
still under the impression that MRI’s will
reveal the cause of their pain. In my opinion,
the main piece of the puzzle that will
tell people what is wrong with them is their
very own history! Physical examination
should confirm what is suspected from talking to
the patient (their symptoms). An MRI is ordered
to prepare someone for surgery and/or to confirm
what is already known from the history and
physical examination!
Let’s take a look at
this article. Over 3000 people were monitored
over eight years. Initial MRI’s were taken, and
then again eight years later. Here is their
summary, “When considering the co-occurrence
of OA (osteoarthritis of the knee) and
performing a stratified analysis, researchers
found no independent association between
meniscal damage and the development of frequent
knee symptoms.”
What does this mean? The bottom line is that an
MRI cannot tell you what is wrong based just on
the MRI finding. It must be taken in context
with the history and physical examination of the
patient. In my opinion what is the “best” MRI?
If you have read our books, you know that it is
“my reproducibility instrument,”
which is my thumb. I poke my thumb into the
injured structure which elicits a “positive jump
sign.” The doctor and the patient both know what
is causing the pain. The patient receives
Prolotherapy to the injured structure to induce
repair and the pain goes away. Even if three to
five visits are required, the whole cost of the
Prolotherapy is often less than the cost of one
MRI.
I’d like to bring up another point in the above
article. The author states that, “Stressing the
importance of treating OA as a whole-joint
disorder, this order calls attention to the risk
of misinterpreting meniscal damage as the direct
cause of knee pain.”
What does this mean?
The bottom line here is this! What treatment
actually treats OA as a whole-joint disorder?
Prolotherapy does! That is why it works for
osteoarthritis! Typically, Prolotherapy for
knee pain is given around the whole joint
because osteoarthritis is a “whole joint”
disorder.
This was a great
study and a great article! Since we are using
the word great, Prolotherapy is a great
treatment for knee pain!
