Metabolic cause of shoulder impingement syndrome

JOURNAL of CHINESE CLINICAL MEDICINE VOLUME 2|NUMBER 9|September 2007
Metabolic cause of shoulder impingement syndrome
Ran Schwarzkopf 1
,Ehud Rath 2
The manifestations of hypothyroidism are well de唱
scribed and can affect virtually any organ.It is impor唱
tant to note that symptoms may be nonspecific in the
early stages of hypothyroidism and do not necessarily
occur in sequence.Musculoskeletal manifestations of
hypothyroidism result from the reduction in metabolic
activity and the deposition and accumulation of hydro唱
philic mucopolysaccharides and glycosaminoglycans in
the ground substance of the dermis and other tis唱
.Examples are carpal tunnel syndrome and De唱
sues [1]
CASE REPORT
quervain disease.Impingement occurs when the soft tis唱
sues of the subacromial space are compressed between
the head of the humerus and the coracoacromial arch
and anterior acromion [2]
.Any condition that narrows
the space between the rotator cuff and the coracoacro唱
mial arch can lead to impingement(Figure 1a&b).Hy唱
pothyroidism may cause entrapment syndromes as a re唱
sult of narrowing the space available to nerves and tis唱
sues due to the accumulation of glycosaminoglycans,
and possibly narrowing the subacromial space as well.
Figure 1 A normal shoulder AP radiograph and normal coronal shoulder MRI(1a,1b)
We present the case of a patient with hypothyroid唱
ism in which a shoulder impingement syndrome re唱
solved after correction of his hypothyroid state.
CASE REPORT
A 37 year old right hand dominant tennis player pres唱
ented at our clinic with a 10 year history of right shoul唱
der pain.He denied any trauma to the shoulder and
previous shoulder discomfort or pain,before the above
10 year period.The pain was exacerbated when playing
tennis especially while serving.He complained of awak唱
ening at night due to the shoulder pain.He had no oth唱
1 NYU /Hospital for Joint Diseases,New York,the United States
2 Orthopaedic Department,Soroka University Medical Center,Beer唱Sheva,Is rael
Correspondence to Ran Schwarzkopf,MD,MSc.,564 East First Ave,Apt 20 G,New York,10016,the United States
E 唱mail: schwarzk@ gmail .com
513
er history of musculoskeletal problems.The patient de唱
scribed a long唱standing fatigue, lack of energy and
weakness.The patient has a history of hyperlipidemia
and obesity.Upon presentation,he was afebrile.
Examination of the right shoulder revealed positive
Neer and Hawkins impingement signs [3]
, positive Jobe
( supraspinatus isolation test,empty can test) [4]
and lift
off tests and negative speed test of the biceps tendon.
No signs of hyperlaxity were noted.Radiographs of the
shoulder were obtained,the radiographic findings of im唱
pingement that include trabecular atrophy( pseudocyst

514 JOURNAL of CHINESE CLINICAL MEDICINE VOLUME 2|NUMBER 9|September2007 formation) under the greater tuberosity of the humeral
head and sclerosis of the undersurface of the acromion
( Sourcil sign) and /or the cortex of the greater tuberos唱
ity were not seen in this patient.Laboratory studies,
which were done routinely,showed an elevated TSH of
160 U /ml, the rest of the studies were within normal
ranges.The patient was managed with 100 mg of thy唱
roxine per day during the week and 150 mg of thyrox唱
ine during the weekend.The patient was not referred to
physiotherapy.After one year of treatment, TSH levels
returned to within normal range,the patient reported to唱
tal alleviation of the shoulder pain and discomfort, ex唱
amination revealed a negative Neer摧s and Hawkin摧s
sign.During the treatment period,the patient reported
occasional use of NSAIDS for pain relief.
DISCUSSION
In the last two decades,subacromial impingement syn唱
drome has become an increasingly common diagnosis
for patients who have a painful shoulder.Many causes
have been proposed for subacromial impingement syn唱
drome.These factors can be broadly classified as intrin唱
sic( intratendinous) or extrinsic ( extratendinous).To
understand the etiology of subacromial impingement, it
is important to understand the unique anatomical char唱
acteristics of the subacromial space.Within this space,
a number of soft唱tissue structures are situated between
two rigid structures.The superior border( the roof) of
the space is the coracoacromial arch,which consists of
the acromion,the coracoacromial ligament,and the cor唱
acoid process.The acromioclavicular joint is directly
superior and posterior to the coracoacromial ligament.
The inferior border( the floor) consists of the greater
tuberosity of the humerus and the superior aspect of the
humeral head.However, interposed between these two
osseous structures are the rotator cuff tendons,the long
head of the biceps tendon, the bursa, and the cora唱
coacromial ligament.Normally,the bursa facilitates the
motion of the rotator cuff beneath the arch.Any abnor唱
mality that disturbs the relationship of these subacromi唱
al structures may lead to impingement.
Normal function of the thyroid gland is directed to
the secretion of the active thyroid hormones that influ唱
ence a diversity of metabolic processes.Hypothyroidism
refers to a metabolic state resulting from a deficiency in
thyroid hormone function, in which decreased caloric
expenditure ( hypometabolism ) is a principal fea唱
ture [1]
.Hypothyroidism can result from any of a variety
of abnormalities that leads to insufficient synthesis of
thyroid hormone.Theprevalenceis3% ~5% of the a唱
dult population.Hypothyroidism usually arises from pri唱
mary thyroid disease(95%),but in rare cases it is due
to hypothalamic唱pituitary disease or generalized tissue
resistance to thyroid hormone [1]
.Hypothyroidism may
manifest in different ways and can affect almost every
organ system in the body.Hypothyroidism can first
present with an assertion of different symptoms.These
symptoms may include fatigue,myalgia,arthralgia,mus唱
cle weakness, stiffness and cramps, dry skin, head唱
aches, and menorrhagia.Brittle nails, thinning of hair,
pallor,and symptoms of carpal tunnel syndrome may al唱
so be seen [1]
.
Clinical connection between hypothyroidism and
musculoskeletal manifestations is well documented in
the literature [5]
such as carpal tunnel syndrome and
Dequervain disease.In clinical observations, we have
had the impression that the prevalence of thyroid dys唱
function in patients with shoulder impingement syn唱
drome is higher than in the normal population.In a re唱
view of the literature, we did not find a study that ex唱
amined the association between rotator cuff impinge唱
ment and hypothyroidism.One possible explanation for
impingement syndrome,in hypothyroid patients,is infil唱
tration of tendon sheaths with glycosaminoglycans; no
studytodatehasevaluatedthishypothesis.
The early recognition of hypothyroidism remains a
challenge,especially when the decline in thyroid func唱
tion is gradual.TSH levels in the blood remains the
most reliable and accessible tool for diagnosing hypot唱
hyroidism.
In the case presented, impingement syndrome
presented in a patient without an overt presentation of
hypothyroidism, and after thyroid function was correc唱
ted,the patient returned to playing tennis without any
further discomfort or need for any adjuvant therapy.Al唱
though the patient has reported intermittent use of
NSAIDS during the treatment period,the amount taken
by the patient,for general pain relief has been well be唱

JOURNAL of CHINESE CLINICAL MEDICINE VOLUME 2|NUMBER 9|September 2007
low therapeutic levels and in very lengthily intervals to
be the primary reason for the improvement seen.But we
can not discard a possible adjuvant contribution.
In conclusion, we believe that further research is
warranted to determine the prevalence of hypothyroid唱
ism among patients with impingement syndrome.
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impingement.OrthopRev,1989 ,18 (9) :963 -975.
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( Editor LEE)