Patients with pain in the lateral aspect of the elbow
who were referred to our Physical Medicine and
Rehabilitation Department for evaluation and agreed to
undergo US only for the purpose of this prospective study
were enrolled consecutively. Participants were considered
to have a diagnosis of unilateral LE. Eligibility criteria for
participation included fulfillment of the diagnostic
criteria for LE, i.e. the presence of pain in the elbow
region and direct and indirect tenderness at or within 2
cm of the lateral humeral epicondyle on resisted extension
of the wrist and/or the third finger
8. Patients were at
least three weeks from the onset of symptoms, and their
condition was flared with activity versus exhibiting
constant pain. Participants who had a history of elbow
fracture or surgery, congenital or acquired deformities of the elbow, bilateral symptoms, or a known inflammatory
rheumatic disorder were excluded
8. The study was
approved by the university ethics committee, and
informed consent was obtained from each patient.
All clinical assessments including physical examination
findings, pain-free grip strength and functional and pain
assessments were performed by the same clinician (ZU).
Information was obtained regarding age, sex, duration of
symptoms, the elbow involved, the dominant arm, and
the presence of cervical symptoms. The cervical spine was
examined by assessing all active movements through
available range with the addition of over pressure to
determine end-feel and pain provocation. Passive
intervertebral movements into flexion, extension, side
flexion, and rotation were then assessed between C4 and
T1. Passive intervertebral movements were determined to
be abnormal if the following three signs were present:
pain was provoked, there was an abnormal quality of
resistance to movement, and an abnormal end-feel was
palpated. Finally, combined movements into extensionrotation
and flexion-rotation were assessed to determine
end-feel and pain provocation. A joint was determined to
be symptomatic if at least one active movement was
painful and exhibited an abnormal end-feel or a combined
movement was painful and exhibited an abnormal endfeel,
and corresponding passive intervertebral movements
were abnormal as determined by the previously described
decision9.
We assessed severity of average pain during the day
and pain under strain (visual analog scale (VAS); 0: no
pain - 100 mm: maximum pain); local tenderness of the
lateral epicondyle after firm pressure was applied to the
painful area (0-3 point scale: absent, mild, moderate,
severe)10; pain on resisted extension of middle finger
and wrist with the arm extended (0-3 point scale: absent,
mild, moderate, severe); pain-free grip strength in the
affected arm (average of two readings with a Jamar
hand-held dynamometer-Sammons Preston, AbilityOne,
US) in each patient11. Grip strength of the uninvolved
limb was also evaluated. Grip strength was measured in
kilograms with the elbow extended and the forearm
pronated since this position was thought to be the most
sensitive for testing12.
Pain and functional disability were also assessed using
physical functioning and bodily pain scales of the Medical
Outcomes Study 36-Item Short-Form Health Survey (SF-
36)13 and a patient-rated forearm evaluation
questionnaire (PRFEQ) for use in LE14. The PRFEQ is
reliable, reproducible, and sensitive for assessment of LE.
It is at least as sensitive to change as the SF-3615. The
overall score of the SF-36 scales, each ranging from 0-100,
in which the higher scores indicated ‘‘better’’ function,
was used. The PRFEQ was designed to assess average arm
pain and function over a one-week period. Five items
were used to assess pain and 10 items to assess function.
The items on the pain subscale of the PRFEQ were scored using a 10-cm visual numeric rating scale with anchors of
0 (no pain) and 10 (worst pain imaginable). The items on
the function subscale were also scored using a 10-cm
visual numeric rating scale with anchors of 0 (no difficulty)
and 10 (unable to do). No other descriptors were placed
along the line. Mean scores for the pain and function
sections and the overall PRFEQ score were calculated.
Ultrasonography evaluation: All patients were
examined with commercial, real-time equipment
(Sonoline G50, Siemens, Seattle, WA, USA) using an 8-12
MHz linear phased array transducer by an experienced
radiologist with over 10 years’ experience in US (ST). The
radiologist was blinded to the clinical details of the
patient. They were positioned comfortably in a chair with
the elbow placed on the examination table in a flexed
position. The common extensor origin was examined in
both longitudinal and transverse planes with respect to
morphology and echotexture. The examination included
comprehensive imaging of the four muscles that form the
common extensor origin. Comparison was made with the
opposite elbow in all patients.
Tendon echotexture was accepted to be normal if a
uniform fibrillar pattern could be traced between the
muscle and the attachment to the lateral condyle.
Tendinopathy was described if there was a loss of this
normal fibrillar pattern that is seen as focal areas of
hypoechogenicity. A partial tear was defined as a focal
anechoic area with no fibers intact or an echogenic
irregular band that could run either horizontally or
longitudinally in the common extensor origin. A complete
tear was defined as a distinct complete interval traversing
or extending through the full width of the common
extensor origin. Confirmation of the abnormality was
performed by imaging at least the two planes.
Enthesopathy was diagnosed if the proximal part of the
common extensor origin was enlarged and there were
echogenicity alterations. Focal areas of calcification and
thickening of the peritendinous lining (peritendinitis)
were recorded, and bursitis on the inferior surface of the
extensor carpi radialis brevis tendon was noted1,4,16.
Consecutive patients were divided into two groups
according to sonographic appearance: Group 1 (US
examination showed no sonographic evidence of LE) and
Group 2 (US examination depicted abnormalities that
confirmed the clinical diagnosis).
Sample size: The sample size required for the study
was calculated based on the primary outcome variable,
that is, grip strength difference between the control and
the painful arm. Power analysis identified 52 patients (24
and 28 patients in Groups 1, 2, respectively) as the total
sample size required to detect a 15% difference in grip
strength between the arms between groups, with a
power of 80% at 5% significance level.
Statistical analysis
We compared groups with chi-square test for nominal
variables. Ordinal variables were compared by Mann-Whitney U two-sample nonparametric tests. The correlations
between physical examination, SF-36 and PRFEQ parameters
and pain or grip strength were determined by the Spearman
test of rank correlation. The critical value for statistical
significance for all tests was set at p<0.05. Analyses were
carried out with SPSS version 10.0.
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