Discussion
Our case report demonstrates an incidental finding of a large,
unruptured AAA during a workup for a chief concern of posterior right
hip and low back pain. Unruptured AAA are typically asymptomatic.
Occasionally, unruptured AAA can become symptomatic and mimic MSK pain
in the flank, back, and/or groin. In the orthopaedic clinic, an AAA is
not high on the differential for a patient presenting with posterior hip
and low back pain. In our case, the patient presented to an
orthopaedic-only urgent care. In this setting, any non-MSK pathology is
usually not considered. However, there is crucial information in the
patient’s history and physical exam that should steer the provider away
from an MSK etiology and towards the diagnosis of an unruptured AAA.
With a chief concern of posterior hip and low back pain in a patient
with a history of bilateral THA, the initial assumption would be muscle
strain or a complication related to the patient’s prostheses. There are
aspects of the patient’s physical exam that align with this orthopaedic
etiology. First, the patient ambulated with a painful right leg and
their gait was antalgic. Additionally, there was reproducible tenderness
on the posterior aspect of the right lumbosacral junction. Reproducible
pain is a commonly known sign of MSK pathology. However, this physical
exam finding is not specific for MSK etiologies and cannot rule out
other causes.
Contrarily, there were important aspects in the HPI and physical exam
findings that point away from MSK pathology. First, the patient denied
any trauma, injury, or falls. Mechanism of injury (MOI) is a vital
component of orthopaedic assessment. With no known MOI, certain injuries
such as muscle strain or periprosthetic fractures are lower on the
differential. However, non-traumatic causes such as infection and
osteolysis must still be considered. An important note from the
patient’s physical exam was the finding that range of motion was fully
intact with no discomfort. Again, this points away from MSK pathology.
The patient’s past medical history is, perhaps, the most important
consideration that would direct a provider towards the diagnosis of an
AAA. The patient’s history is significant for hypertension,
hyperlipidemia, CAD, T2DM, and PAD; all of which are high risk factors
for the development of an AAA. Further, the patient is > 65
years old and male. Both are also risk factors for an AAA. The patient’s
significant cardiac and vascular history, in conjunction with the HPI
and negative findings on orthopaedic physical exam, should logically
lead a provider towards a non-orthopaedic etiology and raise suspicion
for an AAA.
Hip and back pain are an atypical, but known, presentation for an AAA.
This clinical scenario is similar to other cases described in the
literature. Smith et al. reported a 66-year-old male patient with an
8-month history of progressive left hip pain who was incidentally found
to have an unruptured AAA. Baskaran et al. described a 58-year-old
patient with a 6-month history of progressively worsening left hip pain
associated with unintentional weight loss of 38 kg and tender bilateral
testicular swelling. These two cases demonstrated chronic hip pain,
unlike the patient in our report who presented with a 3-day history of
pain. A complaint of chronic pain is more typical of a symptomatic
unruptured AAA, due to the insidious growth of the dilatation. Our case
is unique in this regard. Furthermore, low back pain has been a
well-documented presentation of an unruptured AAA in several case
reports.
Our case report emphasizes the necessity of extracting a thorough HPI
and performing a holistic physical exam in the orthopaedic clinic.
Orthopaedic providers should consider an unruptured AAA as an atypical
differential diagnosis when a patient presents with hip and/or low back
pain. There should be a particularly high index of suspicion for an AAA
in the context of a significant cardiac and vascular history, associated
risk factors (i.e., smoking, T2DM, atherosclerosis, hypertension, etc.),
and negative orthopaedic findings on physical exam. Awareness and
education of this presentation is crucial for avoiding a missed
diagnosis. A missed diagnosis of an unruptured AAA may put the patient
at risk of catastrophic rupture and subsequent death.
Orthopaedic surgery is a field that tends to have a myopic approach to
patient care. With increasingly advanced subspecialties, orthopaedic
surgeons are highly skilled in their respective disciplines.
Inadvertently, differential diagnoses that are typically outside the
field of practice may not be considered. However, it is important for
orthopaedic providers to be well-rounded in all aspects of patient care
and perform holistic investigations when assessing a patient.
This case report has limited generalizability, as it discusses a single
case. However, it highlights important aspects of patient care and can
be used as a teaching tool to advocate for holistic practices in the
orthopaedic clinic.