Case Presentation – Patellar Dislocation
May 11, 2012
32F presents to your family medicine office after ‘dislocating’ her knee the day
previously in a hospital outside of your region. The records are not immediately
available to you. She states that the injury occurred after slipping on a wet
floor with valgus and rotational strain to the right knee. She was in immediate
pain and unable to weight bear. After being brought to the Emergency Room, the
injury was immediately reduced with instant relief. She was sent home with
instructions to follow up with her family doctor.
Background information:
Patellar dislocation occurs most frequently in the second and third decade of
life. The annual incidence is approximately 43/100,000. It is more frequent in
females. There is often a family history of dislocations. It often occurs after
a twisting injury to the knee; however, can also be caused by direct trauma.
There is a high association with osteochondral fractures, often being present
in 35-40% of cases. Lateral dislocation is by far the most common form.
Reoccurence is common, particularly with those who begin dislocations at a
young age.
Acute lateral dislocation of the patella is often obvious. The leg is often held
in 20-30 degree flexion and the patella is felt displaced laterally. Often, the
patella may have spontaneously reduced with knee extension prior to assessment.
Associated tearing of the patellofemoral ligament and retinacular tissue can
lead to hemarthrosis, and medial joint line tenderness.
Questions:
1) What diagnostic tests are appropriate when seeing a patellar dislocation?
2) What is the cornerstone of treatment after acute dislocation? How does this
relate to the most likely mechanism of dislocation?
3) As noted above, medial joint line tenderness is common in patellar
dislocations. What test can be used to differentiate MCL tendon disruption from
patellar pain?
4) What are the indications for orthopedic referral?
Answers:
1) Plain films (AP, lateral, patellar (sunrise/tunnel) knee radiographs given
the high incidence of co-existent fractures
2) Physiotherapy to strengthen the vastus medialus in order to prevent
subsequent lateral dislocations
3) Patellar apprehension test
4) Inability to reduce patella, co-existent fracture, atypical dislocation,
ligamentous injury, positive apprehension test (indicative of patellofemoral
instability), family history of patellar dislocation
Case Presentation – Ischemic ulcers
May 18, 2012
69F presents to the emergency department with a non-healing ulcer on the dorsum of her left foot. She
is hemodynamically stable and afebrile. Her initial blood glucose taken by the nurse is 5.2. She states
that it has been present for over 3 weeks and persists despite the daily application of epsom salts. It is
extremely painful to touch. She is systemically well. She denies any similar ulcers, but does state that her
left forefoot often becomes intermittently blue and painful, but self resolves over several hours. Her
past history is significant only for depression and osteoporosis.
Examination reveals an ulcerated lesion over the head of the 1st metacarpal of the left foot. There is
approximately 3 cm of surrounding erythema. There is no streaking up the leg. No bone or deep
structures are visible. She is neurologically intact. You do however note a cool extremity with decreased
capillary refill and absent pulses.
Background information:
Non-healing ulcers are common in general practice. It is important to differentiate between the various
types of ulcers since their pathophysiology and management options differ greatly. Characteristic
locations and appearance often allows for differentiation between the major types.
The above patient is meant to illustrate a typical presentation of an ischemic ulcer. This diagnosis holds
particular importance as the diagnosis of peripheral artery disease has many implications. For example,
it can affect whether a patient should be on antiplatelet therapy for vascular prevention (see 2010
Canadian Cardiovascular Guidelines on anti-platelet therapy). The presence of peripheral artery disease
is also increases the likelihood of atherosclerosis in other parts of the body.
Questions:
1) What are some features on physical exam / history that can be suggestive of significant bacterial
infection?
2) When should wound cultures be ordered?
3) What would be pertinent to ask in a medical history that could give clues to the etiology of the
ulcer?
4) What are the most common types of chronic ulcers? What features help differentiate them
(appearance, location, etc)?
5) What is the significance of the blue forefoot? What could this represent?
6) What is the test of choice for non-invasive diagnosis of peripheral arterial disease? What values
represent an abnormal result?
Answers
1) Increasing erythema/cellulitis of surrounding skin, induration of surrounding skin, lymphangitis
(streaking), increasing size of ulcer, large amount of drainage, fever.
2) If cellulitis is suspected in order to help guide antibiotic therapy
3) Diabetes, peripheral artery disease, chronic kidney disease, coronary artery disease, ischemic
stroke, smoking status
4) Ischemic ulcers – Due to inadequate perfusion due to arterial obstruction. History is often
consistent with claudication. Dependent rubor may be seen on physical exam. Often are located
over prominent osseous areas or near pressure points (lateral malleoli, tips of toes, metatarsal
heads, bunion area). Usually dry and punctate. Often are painful. Vascular exam is abnormal,
including decreased capillary refill, absence of peripheral pulses, absence of hair, and nail
hypertrophy.
Venous ulcers – Most common type of chronic ulcer. Often located between the knee and
ankle. Malleoli are the most common sites. Pain is not normally predominate. Often moist,
superficial and diffuse. Often co-existing status varicosities, and dermatitis / hyperpigmentation
of surrounding skin.
Diabetic ulcers – Etiolgy is multifactorial, including a combination of diabetic neuropathy,
autonomic dysfunction and vascular insufficiency. Often located in areas susceptible to repeated
trauma (plantar metatarsal heads or dorsal interphalengeal joints). Often have surrounding
hyperkeratotic tissue (callous). Abnormal neurologic exam is often seen.
Malignant Ulcers – Suchs as squamous cell or basal cell carcinoma. Location is variable, can be
seen in sun exposed areas. Skin biopsy should be considered in non-ischemic wounds without
signs of healing.
5) Blue toe syndrome. Usually due to embolic occlusion of digital arteries with atherothrombotic
material from proximal arterial sources. They can be an indicator of further, more serious
attacks in the future.
6) Ankle-brachial index (ABI). It is the ratio between teh ankle systolic pressure divided by the
brachial systolic pressure via Doppler. Normal values are 0.9 – 1.2.
Case Presentation – Scaphoid Fracture
May 25, 2012
42F presents to the Emergency Department after tripping and falling onto an out-stretched hand 2
hours ago. She complains of wrist pain in her right dominant hand. Her vital signs are stable. She
reports no other injuries. Physical examination reveals slight decreased grip strength, ROM, and
palpable pain in the radial side of the right wrist (in particular over the anatomic snuff box of the right
hand). Neurovascular exam is normal. Plain radiographs obtained in the ER, including scaphoid views are
negative for an acute fracture.
Background information:
Scaphoid fractures are among the most common fractures, particularly after fall onto an outstrectched
hand (FOOSH). This is caused by both the direct axial compression and hyperextension of the wrist.
Scaphoid fractures are by far the most common carpal fracture (Figure 1), accounting for up to 60-70
percent of cases.
The most common classification of scaphoid fractures is by location. Approximately 65 percent of
scaphoid fractures occur at the waist (central third). On physical exam, this correlates to tenderness
over the anatomic snuff box (located proximal to the base of the thumb between the extensor pollicis
longus tendon medially and extensor pollicis brevis / abductor pollicis longus laterally). Fractures can
also occur at the proximal pole (15% incidence, correlates to tenderness distal to Lister’s tubercle) and
the distal pole (10% incidence, correlates to tenderness at the volar prominence at the distal wrist
crease).
Questions:
1) What is the most likely diagnosis for the patient in question? What is the relevance of normal x-rays
at initial presentation?
2) What are the management options for this patient? What are some indications for emergent CT/MRI?
3) When would you order a bone scan? How long after injury must one wait in order for focal increased
uptake to be reliably present? What could cause a false positive scan?
4) What is the risk of missing a scaphoid fracture? What specific anatomic features make the scaphoid
prone to this complication?
5) What are some indications for surgical referral?
Answers:
1) Scaphoid fracture. Plain radiographs at the time of injury are notoriously limited in their capacity to
detect acute fractures. Further, they are often unable to provide details regarding fracture
displacement. Keeping this in mind, a high clinical index of suspicion is required when scaphoid fractures
are suspected.
2) Management of symptomatic patients with negative xrays often consists of immobilization in a shortarm thumb spica cast for 7-10 days, followed by re-examination and repeat x-rays. Emergent CT/MRI
rather than expectant management may be useful in some situations. In particular, if the patient is
unable to tolerate prolonged immobilization (eg. Athletes) or if a fracture is noted and the fracture
pattern details are required. There is significant cost and limited availability with these tests – factors
that should be considered before utilizing them in practice.
3) If at repeat examination a strong clinical suspicion remains in the absence of demonstrable fracture
on other diagnostic imaging, a radionuclide bone scan may be indicated. If this is obtained 72 hours after
injury, a negative bone scan has an extremely high sensitivity and effectively excludes a scaphoid
fracture (1). Although highly sensitive, a bone scan is not necessarily specific for a scaphoid fracture and
may be positive due to other local injuries, including non-scaphoid carpal fractures.
4) The risk of non-union in patients with scaphoid fractures that are not immobilized is high. The
scaphoid bone is at particular risk of this complication due to it’s inherent circulation pattern. Arterial
supply enters the scaphoid via the distal pole and travels proximally. This risk is particularly high in
proximal fractures.
5) Open fractures, fractures with neurovascular compromise, displacement >1mm, fractures associated
with increased tilt of the lunate, associated carpal instability, possible scapholunte dissociation,
evidence of non-union or osteonecrosis during follow-up. Practically speaking, referral is often
mandated by the need for consistent follow-up in an available cast clinic.
Figure 1. Carpal bones of the wrist. Taken from UptoDate.
References:
1) Phillips TG, Reibach AM, Slomiany WP. Diagnosis and management of scaphoid fractures. Am
Fam Physician. 2004;70(5):879.
2) UptoDate. Article: Scaphoid Fratures. Accessed June 2012. URL:
http://www.uptodate.com/contents/scaphoidfractures?source=search_result&search=scaphoid+fracture&selectedTitle=1%7E17#H9