Biomedical Engineering Reference
In-Depth Information
6.3.2 Metabolic
Bone disorders involving deficiencies in calcium metabolism secondary to
hormonal, genetic or nutritional imbalance can affect the integrity of the bones
and ligaments of the knee, leading to joint destruction or malalignment [9]. Such
disorders need to be accurately diagnosed and treated with appropriate medical
management in addition to consideration of possible arthroscopy for internal
derangement and corrective osteotomies for extraarticular malalignment problems.
6.3.3 Neuromuscular
Diseases affecting the nerves and muscles of the knee can cause significant gait
disturbances and instability problems. Lumbar disc disease can have a seriously
disabling effect on quadriceps and hamstring function if L
3
, L
4
and L
5
nerve roots
are affected. Other neurological conditions that impair the motor function of the
knee or allow “back-knee” deformities essentially disable a patient from
meaningful ambulation activities without walking aids. Without stability and
motor function, knee fusion becomes a reasonable but drastic alternative to
provide lower limb function.
6.3.4 Infectious
Sepsis of the knee from any gram positive or gram negative bacteria can result in
destruction of the knee joint, known as septic arthritis. These joints are at significant
risk of re-infection, but knee fusion is so disabling that multiple attempts at curing an
infection using antibiotic impregnated bone cement is often attempted, as long as a
functioning extensor mechanism is available and ligamentous stability can be
achieved or substituted during knee replacement surgery. Knee fusion or resection
arthroplasty are last resort options in the case of persistent knee joint infections.
6.3.5 Autoimmune
Arthritis of the knee can be a result of autoimmune disorders such as rheumatoid or
psoriatic arthritis, where the body perceives a foreign antigen to be present, requiring
neutralization by host defenses, even though they are not foreign, but in fact, are the
normal cartilage structure of the host. In the normal defense process, the host
destroys its own normal cartilage by mistake. Evidence suggests that osteoarthritis
has a genetic component that may be related to an autoimmune phenomenon as well.
In any event, these arthritic conditions have a similar end-stage pathology, which
makes them suitable candidates for joint replacement to improve their function.
6.3.6 Post-traumatic
Fractures, dislocations or severe ligament injuries can compromise knee joint
function and in many cases cause severe cartilage destruction, similar to
