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Which of the following would indicate damage to the posterior cruciate ligament?
The posterior cruciate ligament (PCL) is a large ligament located in the center of the knee behind the anterior cruciate ligament. The primary role of the PCL is to provide stability and prevent posterior deviation of the tibia relative to the femur. A posterior drawer test or tibial sag test can be used to assess PCL injury or damage.
In contrast, the anterior cruciate ligament (ACL) prevent anterior deviation of the tibia relative to the femur. Damage to the ACL can be assessed with an anterior drawer test.
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Compartment syndrome is a condition in which pressures around skeletal muscles rise to a level that cuts off blood flow and compresses nerves around the muscles. A 66-year old woman is involved in a high-speed motor vehicle collision and presents with a left femoral shaft fracture. After fixing her bone with an intramedullary rod, the patient is taken to the recovery room. Upon waking she complains of intense pain in her left thigh as well as sensory deficits in the anterior portion of the same thigh. You diagnose her with compartment syndrome and suspect that a nerve is being compromised.
If left untreated, what action do you expect the patient will not be able to perform?
It is likely that the compartment syndrome is compromising the femoral nerve, which would result in an inability to extend the knee. We need to know that the femoral nerve runs close to the femur in the anterior compartment of the thigh. The high compartment pressures have cut off blood supply and compromised the femoral nerve, as evidenced by sensory deficits in the anterior thigh.
The femoral nerve arises from L2-L4 in the lumbar plexus and innervates the quadriceps muscles, which serve to extend the knee.
Flexion of the knee is accomplished by the hamstring muscles, which are supplied by common peroneal and tibial nerves. Eversion of the foot is a function of the peroneus longus and brevis, innervated by the superficial peroneal nerve. Plantar flexion is accomplished by the tibialis anterior, supplied by the deep peroneal nerve. Dorsiflexion is by the tibialis posterior, supplied by the tibial nerve.
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What are the boundaries that define the axilla?
The axilla is an important area housing a large region of the brachial plexus. It is located between the rib cage, scapula, and humerus. More specifically, it is bounded by:
The clavicle, supraspinatus, deltoid, and biceps brachii all lie outside of the axilla region.
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A positive pivot-shift test of the knee, even after a successful anterior cruciate ligament (ACL) reconstruction suggests lack of structural integrity of what ligament?
Although it's function has only recently been described, surgical literature suggests that the anterolateral ligament functions to provide additional rotary stability to the knee. Because of this, some patients who have had an ACL reconstruction, but not an ALL reconstruction, will demonstrate a positive pivot-shift sign, a sign of knee rotational instability upon flexion of the tibia at the knee during medial rotation.
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While testing a patient with shoulder pain, you find that he has a positive anterior slide and positive crank tests. Based on these results, what pathology is the most likely cause of his symptoms?
The anterior slide and crank tests are tests for tears of the glenoid labrum. The following are common tests, with varying diagnostic value, for the other pathologies listed: O'Brien's test (acromioclavicular ligament injury), horn blower's sign (teres minor tear), lift off sign (subscapularis tear), and olecranon-manubrium-percussion test (clavicle fracture).
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A patient comes to you complaining of hip pain. After preforming your exam, you suspect she has avulsed her sartorius from its origin. You order some diagnostic imaging to confirm your diagnosis.
Based on these suspicions, you would expect imaging to show injury to which bony prominence?
The origin of the sartorius Anterior superior iliac spine (ASIS). Accordingly, if the sartorius avulsed from its origin, we would suspect damage to this bony prominence.
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Your patient’s x-ray shows a “Terry Thomas/David Letterman” sign. This finding suggests injury to which structure?
The "Terry Thomas/David Letterman" sign is specific to the articulations of the wrist, and involves injury to the scapholunate ligament. When this ligament is damaged, the scaphoid and lunate drift apart, creating a gap on x-rays reminiscent of the gap in Terry Thomas'/David Letterman's front teeth.
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A patient comes to you complaining of knee pain, after playing soccer two days ago. He states that he felt a “pop” and that he is reluctant to bear weight on his injured knee.
Which of the following findings would make you think he injured his anterior cruciate ligament (ACL)?
Lachman's test has good diagnostic value for ACL tears. The McMurray's and Thessaly tests have mixed diagnostic value, and test for meniscus injuries, the valgus stress tests is a test for tibial collateral ligament injury, and the sag sign tests for posterior cruciate ligament (PCL) injury.
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which test would be used to determine an anterior cruciate ligament (ACL) rupture?
A Lachman's test requires the clinician to apply an anterior force on the tibia, looking for an end-feel (or resistance created by the ACL). Godfrey's (90-90), posterior drawer and quadriceps active test all test for a rupture, or sprain of the posterior cruciate ligament (PCL). McMurray's tests for meniscal tear.
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Which structure(s) would have a tensile force applied with hyperflexion of the knee?
The anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) are both affected with hyperflexion of the knee, as these two ligaments are located deep inside the knee capsule, and prevent anterior and posterior sheering forces. If this action occurred with enough force, these structures would be injured. The sedial collateral ligament (MCL) and lateral collateral ligament (LCL) would be injured with a valgus or varus force, both with occur in the coronal plane. The iliotibial band (ITB) and and medial collateral ligament (MCL) would require multiplaner forces in order to be injured.
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Since ATP regeneration occurs through oxidative phosphorylation, we are able to calculate ATP usage during exercise by tracking the volume of oxygen flow in a test subject, and calculating the amount of oxygen used. This method of indirectly measuring ATP usage during exercise requires use to know the ratio of high energy phosphates (ATP) generated per unit of oxygen (O2).
What is the typical production ratio of high energy phosphates (ATP) per unit of oxygen (O2)?
Oxidative phosphorylation generates roughly 6.3 high energy phosphates (ATP) per unit of oxygen (O2).
It is also important to note that ATP generation occurs anaerobically via lactic acid production, with the ratio being 1.5 high energy phosphates (ATP) per unit of lactate. But this is not the correct answer in this context.
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A patient in your clinic complains of knee pain, and demonstrates a positive lever sign. The positive lever sign suggests what structure is injured?
Although it is a very new test, the available literature suggests that the lever sign has superior diagnostic value to the Lachman, pivot-shit, and anterior drawer tests, to detect anterior cruciate ligament (ACL) injuries. Additionally, the preliminary evidence suggests that the lever sign has high diagnostic value for both acute and chronic ACL injuries.
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