A twenty-three-year-old woman was seen because of a twenty-month
history of stiffness and pain in the right hip. The first symptom was
stiffness in the hip, followed by the onset of pain in the right groin
approximately two months later. The pain was cyclical in nature and always
occurred twenty-four to forty-eight hours after the onset of her menstrual
period. It lasted for ten to twelve days and then gradually subsided until her
next monthly period. The pain and stiffness progressively worsened, resulting
in marked external rotation and flexion of the extremity and a limp during
walking. The pain was exacerbated by activity but was also present at rest and
had been unresponsive to several trials of nonsteroidal anti-inflammatory
medications. The patient had no history of trauma. She worked as a
radiographic technician and was otherwise healthy, with her only medications
being oral contraceptives for the treatment of dysmenorrhea. She had a smoking
history of eight cigarettes per day for the past six years.
She was seen by an orthopaedic surgeon approximately one year after the
onset of symptoms. She was noted to have marked limitation of internal
rotation of the hip. Radiographs were suggestive of an old slipped capital
femoral epiphysis, which was thought to explain the external rotation and
flexion contracture. She was referred to a gynecologist for further evaluation
of the pain. The findings of the pelvic examination were unremarkable. A
pelvic ultrasound study revealed normal findings. An intravenous pyelogram did
not reveal any abnormalities of the kidneys or ureters. An exploratory
laparoscopy revealed papillary lesions on the surface of the right ovary.
These lesions were biopsied, and the pathologic diagnosis was consistent with
reactive fibrosis.
Three months later, the patient consulted another orthopaedic surgeon, who
noted tenderness at the posterior-superior iliac spine and the adductor
origins from the pubis as well as a fixed external rotation contracture of the
hip. Magnetic resonance imaging revealed diffuse hypertrophy of the right
obturator internus muscle and signal changes consistent with hemorrhage. The
differential diagnosis included an inflammatory condition, trauma (which was
inconsistent with the history), and endometriosis. A variety of nonsteroidal
anti-inflammatory medications did not relieve the symptoms. Two months later,
the patient was evaluated by a third orthopaedist, who noted that the patient
stood and walked comfortably with the hip externally rotated approximately
90° during gait and that she had an external rotation contracture of
30° when lying in the supine position. Abduction was limited to 20° on
the right, compared with 70° on the left. The right hip had a 30°
flexion contracture, with flexion to 80°. The range of motion of the right
knee was normal. A repeat gynecologic examination and Pap smear were
negative.
The patient was then referred to our institution for further evaluation and
treatment. At that time, she was found to walk with the right lower extremity
externally rotated approximately 45°. The hip was fixed in 45° of
external rotation and 5° of abduction with no internal rotation, external
rotation, abduction, or adduction from this position. The right hip had a
flexion arc of 30° to 70°. Straight-leg raising did not elicit pain.
The girth of the right thigh was 2 cm smaller than that of the left thigh when
measured 5 cm proximal to the superior pole of the patella. Sensory and
vascular examinations of the lower extremities revealed normal findings. The
motor examination revealed normal findings except for mild weakness of hip
flexion, which was classified as grade 4 (of 5). No palpable masses or
lymphadenopathy was detected.
Radiographs showed demineralization of the right femoral head and neck and
external rotation of the right hip (Fig.
1). Laboratory studies revealed a hemoglobin level of 13.1 g/dL, a
white blood-cell count of 7.9 × 109/L, a platelet count of
254 × 109/L, an erythrocyte sedimentation rate of 11 mm/hr, a
negative test for antinuclear antibodies, a C-reactive protein level of 1.9
mg/dL, a rheumatoid factor level of <20 IU/mL, and an anti-DS-DNA level of
4 IU/mL. A triple-phase technetium-99 bone scan revealed hyperemia of the soft
tissues of the medial aspect of the proximal part of the right thigh, and the
bone images showed focal areas of uptake in the right ilium, the right
ischium, and the inferior part of the right acetabulum. These findings were
interpreted as being consistent with infiltrative disease or increased
bone-remodeling secondary to bone stress. A computerized tomographic scan
demonstrated a 5 to 7-cm-diameter mass in the right obturator fossa. A
computerized tomography-guided needle biopsy of the mass was performed, and a
pathologic diagnosis of endometriosis was made. In addition, pelvic
ultrasonography showed some evidence of an endometrioma inside the right
ovary. A repeat pelvic magnetic resonance imaging scan with and without
gadolinium was performed to better delineate the extent of the disease
process. This scan showed multiple punctate foci of increased signal about
both pelvic sidewalls, particularly on the right, which were thought to
represent small endometrial implants or endometriomas
(Fig. 2). The right obturator
internus and externus muscles were seen to be thickened and contained multiple
focal lesions consistent with the diagnosis of endometriosis. Tiny areas of
endometriosis involving the right adnexa were also seen. These lesions were
best seen on axial proton-density T2-weighted images without fat
saturation.
The patient underwent an exploratory laparotomy and right pelvic dissection
by a gynecologic surgical team, followed by a right hip exploration by our
orthopaedic team. The right ovary was noted to have a surface lesion that was
consistent in appearance with a cystadenofibroma. This ovary and the right
fallopian tube were resected. The left ovary appeared normal. There was
thickening along the right pelvic sidewall, and the posterior part of the
uterus and cul-de-sac contained obvious foci of endometriosis. These foci were
biopsied, and the diagnosis was confirmed histologically intraoperatively.
Nodal tissue surrounding the external iliac artery and vein was removed.
The obturator nerve was noted to be compressed but was dissected free of the
pelvic sidewall. The sidewall mass was resected as completely as possible, and
later histologic examination confirmed the diagnosis of endometriosis. The
inferior part of the abdomen was further explored. No classic "pocket
sign," or retraction of the soft tissue into the sciatic notch resulting
from contracture caused by the
endometriosis4, was
seen during the exploration. The abdomen was closed, and the patient was
placed in the left lateral decubitus position. The hip was exposed through a
curved lateral incision centered on the greater trochanter. The fixed external
rotation contracture made exposure of the posterior part of the capsule
difficult. The short external rotators were identified and released, which
resulted in approximately 10° of additional internal rotation. In spite of
the findings seen on magnetic resonance images, there was no histologic
evidence of endometriosis in the short rotators or the capsule, but both were
thickened. The sciatic notch was palpated, and no masses were detected. A
longitudinal posterior capsular release at the margin of the acetabulum was
then performed, allowing for approximately 50° of internal rotation of the
hip. The short external rotators were left unattached, and the fascia and
wound were closed.
Pathological examination of the resected specimen revealed a 3.3 × 2
× 1.8-cm fibroma of the right ovary and a normal fallopian tube. The
findings of the cul-de-sac biopsies were consistent with endometriosis.
Examination of seven lymph nodes obtained from the right obturator fossa
revealed endometriosis in a single node. Lymph nodes obtained from the right
pelvis and the area surrounding the obturator nerve were normal. Histologic
examination of the hip capsule revealed dense fibrovascular connective
tissue.
Postoperatively, the patient maintained a full range of motion of the hip
but had some recurrence of the pelvic pain. Lupron Depot (leuprolide acetate)
injections were begun, and an exercise program was prescribed. Three years
postoperatively, the patient reported a continued full range of motion of the
right hip but had some persistent pain, which was controlled with hormone
therapy.
Our patient had a fixed flexion and external rotation contracture of
the hip and cyclic pelvic and groin pain secondary to endometriomas that were
lying adjacent to the obturator nerve and were causing edema and contracture
of the obturator externus and internus muscles. The hip contracture was
primarily capsular in origin as it was mostly relieved by surgical release of
this structure. However, a component of the contracture was also muscular in
origin as release of the short external rotators also helped to restore some
hip motion. The groin pain probably was due to cyclic compression of the
obturator nerve by the periodic hypertrophy of the endometrial tissue
stimulated by estrogen and progesterone during the menstrual cycle. It is
interesting that the symptom of stiffness preceded the pain in this patient.
This finding may indicate that there was involvement of the short external
rotators before symptomatic obturator nerve compression developed.
The location of the endometrial tissue and the presence of a fixed
hip-joint contracture in our patient are unique findings that apparently have
not been described in previous reports in the literature. Cyclic pain in the
hip region often has been attributed to involvement of the sciatic nerve, and
there have been reports of hip, thigh, or groin pain due to endometriomas
involving other structures, including the lateral pelvic sidewall and
retroperitoneum, the deep hamstrings fascia, the external oblique aponeurosis,
the pubic tubercle, the obturator foramen, the ureter, the ilioinguinal nerve,
and the extraperitoneal portion of the round
ligament1,5-7.
However, we have not encountered any other published reports in which the
short external rotators were involved. In addition, fixed hip contracture
followed by cyclic groin pain has not been previously reported as a presenting
symptom complex in association with endometriosis.
Bjornsson1 described
the case of a patient who had cyclic sciatica with a coexisting hip abduction
contracture due to an endometrioma extending into the obturator foramen.
However, the contracture occurred late (after surgical excision of the
endometriosis lesion), developed after hormone suppression therapy had ceased,
and remitted after hormone therapy had been resumed.
The mechanism by which the endometriomatous tissue infiltrated the short
external rotators is unknown. Other
investigators2,5-7
have suggested hematogenous or lymphatic seeding in cases of ectopic foci.
Smith and Ward8
proposed that the mesocolon provides a direct anatomical pathway for extension
of intra-abdominal access to the hip region. The mesocolon may allow for
spread along the iliopsoas muscle, which inferiorly is in intimate contact
with the hip capsule. It is possible that a similar pathway of direct
extension via the retroperitoneum and obturator foramen led to ectopic foci of
endometriosis in this case. Regardless of the mechanism, the case of our
patient is consistent with the observation by Pellegrini et
al.6 that 88% of
documented extraperitoneal lesions have been unilateral and have involved the
right side.
Other cases of cyclic pain about the hip due to endometriosis have been
treated successfully with surgical excision, hormone suppression, or
both1-7,9.
Our patient had both of these treatments in addition to a release of the
structures that were contributing to the extreme rotation contracture of the
hip. It is doubtful that joint motion would have been regained with
hormone-suppression therapy alone because of the fibrotic, contracted nature
of the hip-joint capsule and the involvement of the short external rotator
muscles.
In conclusion, endometriosis should be considered in the differential
diagnosis for women of childbearing age who have hip contracture along with
pelvic and/or groin pain related to the menstrual cycle. ?