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.

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.

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 pectoralis major muscle anteriorly
• The latissimus dorsi, teres major, and subscapularis muscles posteriorly
• The shaft of the humerus laterally
• The serratus anterior and rib cage medially

The clavicle, supraspinatus, deltoid, and biceps brachii all lie outside of the axilla region. 

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.

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).

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.

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.

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.

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.

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.