Knee Arthroplasty

By: Simranjit Rekhi

History of Knee Arthroplasty

• Arthroplasty of the knee was first performed in the late 1960s

• With improvements of arthroscopes and higher-resolution cameras, – the procedure has become highly effective for

both the accurate diagnosis and proper treatment of knee problems

Who gets this surgery?

• People to experience severe pain in the knee– Restricting ordinary activities of daily living

• People usually over 65 that have knee cartilage wearing away

• 600,000 people worldwide have knee replacements every year.

Significance of a Knee Joint

• Knee is that largest joint in the body• Upper and lower leg bones are joined by a

complex array of ligaments, tendons, muscles and cartilage

• Kneecap, or patella, which serves as a bony fulcrum for the knee muscles to slide over and amplify strength and torque– knee can not only bend and flex, it can twist and rotate

Knee Anatomy• Hyaline cartilage - Thick

cushioning (cartilage) covers and protects the ends of your bones.

• Meniscal cartilage or meniscus, acts like a shock absorber between the bones and keeps the knee joint stable by spreading out the load evenly across the joint

• Articular cartilage, a smooth substance that cushions the bones and enables them to glide freely

What causes Knee Arthroplasty • Torn meniscal cartilage• Loose fragments of bone

or cartilage • Abnormal alignment or

instability of the kneecap• Inflammation of the

Synovial membrane– Fluid lubricates knee

(reduces friction)

• Torn ligaments, including the anterior and posterior cruciate ligaments.

Osteoarthritis

• The cartilage that protects and cushions the knee joint breaks down over time.

• Bone surfaces rub against each other– Damage to

tissue and bone

Knee Arthroplasty Procedure

Non-Constrained Knee Replacement

• The artificial components inserted into the knee are not linked to each other

• Rely exclusively on the body’s muscles, ligaments, and tendons to keep the kneecap in place.

• no stability built into the system. • Most common type of replacement

Constrained Knee Replacement

• Used when the knee is highly unstable and the person's ligaments will not be able to support the other type of knee replacements• Severely damaged knees

• The two pieces are connected with a hinge-like device that keeps the joint in-line and helps support the kneecap's proper alignment and function.

– Though It doesn’t last as long as the other knee replacements

Unicondylar Knee Replacement

• It is performed if the damage is limited to one side of the joint only with the remaining part of the knee joint being relatively spared

• The incision is only three inches compared to 8 inches for a total knee replacement

• Less invasive and more successful

Post Surgery• Physical Therapy • Gradually return to normal

activities– Walking, climbing stairs– No running, playing tennis as it

may wear the artificial joints • Doctors recommend a CPM

(Continuous Passive Motion)– It slowly and smoothly bends

and straightens your knee• Stationary Bicycle – regain

strength in knee and leg muscles

• Swimming

Different models of Knee Replacements

• Stryker & Wright Medical Technology Inc.- produce metal implants made from nickel chrome alloys– Though there is toughness in these systems, they

tend to roughen and scratch over time

Scorpio NRG Knee Flexed ™

Triathlon PS Knee System ™

Scorpio TS Revision Implants Front View ™

ADVANCE STATURE® Knee

Continued…

• Smith & Nephew Orthopaedics – enhanced the Genesis II and Profix, to Oxinium – Durability – Reduced the rate of polyethylene wear by 85%– 93% survival rate 10 years after surgery

GENESIS II ™ PROFIX™

Websites used• http://www.ehealthmd.com/library/totalkneereplacement/TKR_types.html#non • http://en.wikipedia.org/wiki/Knee_replacement • http://emedicine.medscape.com/article/1250275-overview • http://arthritis.webmd.com/knee-replacement-surgery• http://orthoinfo.aaos.org/topic.cfm?topic=a00299 • http://physicianlink.uams.edu/casestudies/csknee.asp • http://www.ehow.com/about_5501233_semi-constrained-knee-replacement-infor

mation.html

• http://www.physicaltherapyweb.com/news/wp-content/uploads/2010/02/total_knee_arthroplasty_200.jpg

• http://www.medcompare.com/spotlight.asp?spotlightid=55 • http://www.stryker.com/en-us/products/Orthopaedics/KneeReplacement/

Primary/ScorpioNRG/index.htm# • http://global.smith-nephew.com/master/OXINIUM_GENESISII_PROFIX_22462.htm • http://global.smith-nephew.com/us/PROFIX_TOTAL_KNEE_SYSTEM_2972.htm