not bad… 2012 in review ^^

The stats helper monkeys prepared a 2012 annual report for this blog.

Here’s an excerpt:

600 people reached the top of Mt. Everest in 2012. This blog got about 4,100 views in 2012. If every person who reached the top of Mt. Everest viewed this blog, it would have taken 7 years to get that many views.

Click here to see the complete report.

the Ankle Joint: some hints

The ankle is the region where the foot and the leg meet. The ankle joint is actually composed by three smaller joints:

  1. the ankle joint proper, commonly called ankle mortise joint (but also talocrural joint).  It is a synovial hinge joint that connects the distal ends of both the tibia and the fibula in the lower limb with the proximal end of the talus.
  2. the subtalar joint, that occurs at the meeting point of the talus and the calcaneus.
  3. the inferior tibiofibular joint, between the fibula and the tibia. More precisely, it is formed by the rough, convex surface of the medial side of the distal end of the fibula, and a (corresponding) rough concave surface on the lateral side of the tibia.

ankle joint and its three sub-joints

The boney architecture of the ankle consists of three bones: the¬†tibia, the¬†fibula¬†(in the leg)¬†and the¬†talus¬†(in the foot).¬†The talus is also called the¬†ankle bone since it’s the most important bone in the ankle articulation.¬†In normal health conditions, the articulation between the tibia and the talus (ankle mortise joint) bears the greatest part of body weight: it is the region where ankle efforts are mostly concentrated.

The medial malleolus is a boney processmalleoli extending distally off the medial tibia. There is also a lateral malleolus, generated by a distal-most aspect of the fibula. Together, the two malleoli, along with their supporting ligaments, stabilize the talus underneath the tibia.

The ankle joint is bound by the strong deltoid ligament (it is attached at the medial malleolus of the tibia and supports the medial side of the whole joint) and three lateral ligaments: the anterior and posterior talofibular ligaments (they support the lateral side of the joint, from the lateral malleolus to the dorsal and ventral ends of the talus) and the calcaneofibular ligament (it is attached at the lateral malleolus and to the lateral surface of the calcaneus).

ankle ligaments

Achille's tendonThe calcaneus is also attached to the Achille’s tendon¬†(also known as the¬†calcaneal tendon¬†or the¬†tendo calcaneus), that is a tendonous extension of gastrocnemius¬†and¬†soleus¬†muscles of the leg. It attaches the heel to the¬†posterior¬†leg.

Concerning the joint motion, the ankle joint theoretically admits 1 degree of freedom: movements of plantar flexion and dorsiflexion.

ankle motions

In addition to these, the geometry of the different bones that form the articulation permits other more limited movements, such as foot eversion and inversion.

sources: Wikipedia and this website

the Hip Joint: some hints

The¬†femur head¬†(Latin:¬†caput femoris)¬†hip joint bonesis the highest part¬†of the thigh bone (femur).¬†It has a roughly semispherical shape, with a short ‚Äúneck of the femur‚ÄĚ angling the head anteriorly, medially and superiorly to fit into the acetabulum of the pelvis bone.

The acetabulum, also called socket, is the cavity in the pelvis which “hosts” the femur head. It is¬†formed by three innominate bones: the ilium, the ischium and the pubis.

The femur head’s surface is smooth and normally coated with¬†cartilage. It¬†is supported by the neck of the femur and¬†gives attachment to one single intracapsular ligament,¬†the “ligament of head of femur” (ligamentum teres, on the top of the femur head in the figure on the left). head of femur and its ligamentIt may be not¬†that important as a ligament (it is only stretched when the hip is dislocated, and may then prevent further displacement) but can often be vitally important as a conduit of a small artery to the head of the femur. This small artery¬†is not present in everyone but can become the only blood supply to the bone in the head of the femur when the neck of the femur is fractured or disrupted by injury in childhood.

The femur head together with the acetabulum form the hip flexion-extensionHip Joint. The hip joint has three degrees of freedom, since it can move in three different planes:

  1. sagittal plane: flexion/extension of the leg.
    With just this movement, approximately 3 to 3¬Ĺ times the body weight acts on the hip joint. An example of this motion is shown by the figure on the right.
  2. hip adduction-abductionfrontal plane: abduction/adduction of the leg. Regardless of the direction, the respective supporting leg is then subject to approximately 3 times the body weight. This kind of motion is represented by the figure on the left.
  3. transverse plane: external/internal femur rotationrotation of the femur with respect to the pelvis bone. This motion, typical when crossing  legs, makes the femur head rotate in several directions. An example is shown by the figure on the right.

The head of the femur is attached to the femur shaft by a thin neck region that is often prone to fracture in the elderly, which is mainly due to the degenerative effects of osteoporosis. If there is a fracture of the neck of the femur, the blood supply through the ligament becomes crucial. In orthopedic surgery, the Total Hip Arthroplasty surgery consists in removing the femur head and the acetabulum and replacing them with a total prosthesis.

Normally, the two involved prosthetical components are:

  1. the Acetabular Cup, a shell that fits the pelvistotal hip prosthesis components bone to replace the acetabulum. It is usually attached to the bone by using friction or cement. Additional fixation can be achieved by means of screws.
  2. the Femoral Component, that is a stem with attached prosthetic femoral neck and head (a ball that fits the Acetabular Cup). Femoral bone is removed and the femur is shaped to accept the femoral stem.

The figure below shows the difference between a healthy hip (on the left) and a prosthetic hip (on the right).

hip before and after

sources: Wikipedia, this website and this other website