Lower Extremity

Surface anatomy (or living anatomy as it is sometimes called) is important for understanding the human body and its function. When examining a patient, structures are often more difficult to locate than on an anatomical specimen. Much of what we are looking for is not necessarily visible to the naked eye. To further complicate matters, people are different! While most humans fall within a ‘normal’ range of size and proportion, there is a great deal of variability between individuals. The structures that you find displayed clearly and concretely in an anatomy textbook may not always appear that way on a living person. As an example, leg alignment of the lower extremity can vary among patients. As a clinician, it is important to appreciate this variability and develop skill in locating the same structure on different people. The best way to learn how to do this is to practice palpation on as many people as you can, paying close attention to variations in such things as size, shape and gender.

[ L126 ]

Anteroposterior radiographs allow key aspects of the hip bone and pelvis to be visualized.

a Fractures can occur as a result of high-energy trauma that leads to a disturbance in the shape and orientation of the pelvic inlet or outlet.

b Violent muscle contraction can also result in an ‘avulsion type’ fracture to areas of the pelvis that provide attachment for large muscles.

a [ G198 ], b [ E513-002 ]

A total of 14 structures (seven nerves, six vessels, one muscle) passes through the greater sciatic foramen, while four structures (two nerves, one vessel, one muscle) pass through the lesser sciatic foramen. The piriformis muscle serves as a key anatomical landmark for locating the greater and lesser sciatic foramina. It arises from the anterior (pelvic) surface of the ­sacrum, courses through the greater sciatic foramen, and attaches to the greater trochanter of femur. Only the superior gluteal nerve and vessels are located superior to the piriformis muscle, as they exit the pelvis.

a A ‘hip fracture’ refers to a fracture of the proximal ¹ / ₃ of the ­femur. It is commonly observed as a result of a low-energy ­impact (e.g. a fall to the side while walking) in an elderly patient population, with the incidence of injury doubling for each decade past 50 years of age.

b Hip fractures typically occur in either the neck of femur or intertrochanteric regions.

c In adults, the ­medial circumflex femoral artery is the primary blood vessel for the head of femur. The lateral circumflex femoral artery mainly supplies the neck of femur. The acetabulum is supplied by the obturator artery and superior gluteal artery . In­tracapsular fractures of the neck of femur can lead to disruption of the blood supply to the head of femur and result in complications such as non-union and avascular necrosis (AVN). While intertrochanteric fractures typically have lower rates of avualar necrosis (AVN) and non-union (because it is a fracture in the extracapsular ­region), they often require more robust stabilization. a [ M614 ], b [ L126 ], c [ L266, L127 ]

a Orthopedic research suggests that the position and shape of the acetabulum and the head of femur are important factors that may be associated with the onset and progression of degenerative conditions of the hip joint such as osteoarthritis.

b Degenerative changes may result in the hip joint needing to be replaced with an ‘artifical ball-and-socket style joint’ via hip ­arthroplasty.

[ M614 ]

The muscles of the gluteal region play a key role in stabilizing the hip joint during change of direction movements in sport, as well as when landing from a jump. Weakness of the gluteus medius and minimus muscles or injury to the superior gluteal nerve (which innervates these muscles) can result in ineffective stabilization of the hip joint, and lead to the knee joint experiencing a large valgus force (or knee adduction moment) during movement. This abnormal knee movement may be associated with the occurrence of traumatic knee injuries such as a torn anterior cruciate ligament.

a [ G728 ], b [ L231 ]

As a result of its attachment to the vertebrae of the lumbar spine , tightness of the psoas major component of the iliopsoas muscle complex can lead to an increased lordotic curve of the lumbar spine. This muscle tightness/inflexibility can result in low back pain which occurs following vigorous activities that involve hip extension movements during which the ‘tight’ psoas muscle repeatedly lengthens. Prolonged sitting (i.e. working at a desk or driving a vehicle) with the hips in a flexed position (which places the iliopsoas muscle in a shortened position) is believed to be one possible cause of psoas major muscle tightness. [ L231 ]

The anterior thigh or ‘quads’ region can be severely contused as a result of a blunt force trauma. As the magnitude of the force increases, so does the damage to the region. Severe contusions can result in a dramatic loss of muscle strength, restricted range of motion, and cause a significant amount of pain and skin discoloration (ecchymosis) in the region. A complication that can be associated with severe bruising in the quadriceps region is a condition known as myositis ossificans . It occurs as a result of ectopic calcification that is associated with trauma to both the quadriceps muscle and the underlying bone.

a [ J787 ], b [ E969 ], c [ J787-046 ]

a The topography of the gluteal region explains why intramuscular injections must be applied into the gluteus medius, not into the gluteus maximus . Incorrectly placed injections may cause bleeding and injuries to the nerves which innervate the muscles that power movements of the hip (superior and inferior gluteal nerves) and the knee (sciatic nerve). Lesions of the superior gluteal nerve can lead to paralysis of the gluteus medius and minimus muscles or the tensor fasciae latae .

b This type of injury may manifest itself as a positive TRENDELENBURG’s sign – an inability to keep the pelvis level when performing single leg balance on the affected side.

a [ L126 ], b [ L127 ]

Degenerative changes within the knee joint can occur secondarily to injury (e.g. following a torn anterior cruciate ligament or meniscus), or as the result of abnormalities in joint alignment. Knee osteoarthritis (OA) is most commonly diagnosed via plane radiography. The KELLGREN and LAWRENCE classification system is used to grade the degree of knee OA. Grade 0 (none, a ) – no radiographic findings of OA; grade 1 (doubtful) – doubtful narrowing of joint space and possible osteophytic lipping; grade 2 (minimal OA) – definite osteophytes, definite narrowing of joint space; grade 3 (moderate OA) – moderate multiple osteophytes, definite narrowing of joint space, some sclerosis and possible deformity of bone contour; grade 4 (severe OA, b ) – large osteophytes, marked narrowing of joint space, severe sclerosis, and definite deformity of bone contour.

b [ M614 ]