Ultra High Molecular Weight Polyethylene

Ultra high molecular weight polyethylene or UHMWPE  is a subset of the thermoplastic polyethylene which and large  molecular weight. It is a very tough material, with the highest impact strength of any thermoplastic presently made.

This substance is used in making components of prosthesis for joint replacement.

An Overview of Fractures of Distal Radius

Understanding and management of fractures of distal end of radius have come a long way. Consider this statement by Abraham Colles made two centuries back.

“One consolation remains that limb will , at some remote period enjoy perfect freedom in all its motions, and be completely exempt from pain. The deformity, however will remain undiminished throughout the life.”

Modern management of these fractures have made these statement a history. Much has been understood about complexities of fractures of distal end radius and the management has evolved a lot incuding the techniques and instruments.

Broadly speaking fractures can be either extra-articular or intra articular [Not involving or involving the joints].

What has been described as Colles fracture is an extra-articular fracture of the distal end of radius. [Read more]

Neoplasm

Neoplasm is an abnormal mass of tissue as a result of neoplasia.

Neoplasia means new growth in Greek. It denotes abnormal proliferation of cells.

The growth of this clone of cells exceeds, and is uncoordinated with, that of the normal tissues around it.

One of the features of the neoplastic growth is that it persists in the same excessive manner even after cessation of the stimuli.

Neoplasms may be benign, pre-malignant or malignant.

The term tumor is synonymous with a neoplasm that has formed a lump.

Not all neoplasms form lumps.

Tectorial Membrane

It is also called Membrana Tectoria and  is situated within the vertebral canal.

It is a broad, strong band which covers the odontoid process and its ligaments, and appears to be a prolongation upward of the posterior longitudinal ligament of the vertebral column.

It is fixed, below, to the posterior surface of the body of the axis, and, expanding as it ascends, is attached to the basilar groove of the occipital bone, in front of the foramen magnum, where it blends with the cranial dura mater.

Its anterior surface is in relation with the transverse ligament of the atlas, and its posterior surface with the dura mater.

A membrane of similar name also exists in cochlea.

Posterior Longitudinal Ligament

The posterior longitudinal ligament is situated within the vertebral canal, and extends along the posterior surfaces of the bodies of the vertebrae, from the body of the axis, where it is continuous with the membrana tectoria, to the sacrum.

It is broader above than below, and thicker in the thoracic than in the cervical and lumbar regions.

The ligament is more narrow at the vertebral bodies and wider at the intervertebral disc space. This is significant in understanding certain pathological conditions of the spine such as the typical location for a spinal disc herniation.

At  intervertebral fibrocartilages and contiguous margins of the vertebrae, the ligament is more adherent and  broad.

It is narrow and thick over the centers of the bodies, from which it is separated by the basivertebral veins.

It has an anterior counterpart called anterior longitudinal ligament

Joint Replacement – History, Present and Future

History of joint replacement is quite interesting. Earliest method for treating arthritis  was interposition arthroplasty using soft and flexible materials.

But these substances lacked strengths and were not rigid enough to support.

Metal and glass  were tried next in the form of condylar shapes attached to one of the joint. These provided some amount of success but joint apposition was not perfect and neither were kinematics of the joint.

Modern day joint replacement began in the early 1960s. This was hallmarked by introduction of  cemented metal-polyethylene components for the hip. Later  Gunston used this technique in the knee also.

Charnley prop0sed following principles of arthroplasty which are still valid today. [Read more]

Anterior Longitudinal Ligament

The anterior longitudinal ligament is a ligament that runs down the anterior surface of the spine. It traverses all of the vertebral bodies and intervertebral discs.

This ligament is thick and slightly more narrow over the vertebral bodies and thinner but slightly wider over the intervertebral discs which is much less pronounced than that seen in the posterior longitudinal ligament.

Its posterior counterpart is called posterior longitudinal ligament.

What Is Joint Replacement?

Joint replacement is a common orthopedic procedure done worldwide. A joint replacement aims at of replacing painful, arthritic or diseased parts of the joint with artificial surfaces.

The artificial joint is called prosthesis.

Hip and knee replacements are very common form of joint replacements. In medical terms the joint replacement is called replacement arthroplasty or total arthroplasty or sometimes simply arthroplasty.

Actually arthroplasty means repair of the joint. Earlier, a popular form of arthroplasty was interpositional arthroplasty with interposition of some other tissue like skin, muscle or tendon to keep inflammatory surfaces apart. [Read more]

Intervertebral Foramen

Between every pair of vertebræ are two apertures, the intervertebral foramina.

The foramen allows for the passage of the spinal nerve root, dorsal root ganglion, the spinal artery of the segmental artery, communicating veins between the internal and external plexuses, recurrent meningeal  nerves, and transforaminal ligaments.

Their size is variable due to placement, pathology, spinal loading, and posture.

They can be occluded by arthritic degenerative changes and space-occupying lesions like tumors, metastases and spinal disc herniations.

What Is Bone Graft

Bone grafting is a commonly performed surgical procedure. A bone graft transplants bone tissue. Bone grafts to repair and rebuild diseased bones in your hips, knees, spine, and sometimes other bones and joints. Grafts can also repair bone loss caused by some types of fractures or cancers. Once your body accepts the bone graft, it provides a framework for growth of new, living bone.

Bone has the ability to regenerate completely if provided the space into which to grow. As native bone grows, it  replaces  the graft material completely and results in a fully integrated region of new bone.

Depending upon the source where the graft is taken from, the bone grafts can be autograft or allograft.

Autograft

Also called autologous or autogenous bone graft, this kind of graft is obtained from the same individual receiving the graft. Bone can be harvested from non-essential bones, such as the iliac crest. Iliac crest is most common source of autografts in orthopedic surgery. Other places where graft can be taken from is fibula or metaphyses of long bones. [Read more]

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