Oxford® Partial Knee
Michael O. Williams, M.D., F.A.A.O.S.
Oxford Partial Knee Replacement
The Oxford partial knee replacement is
indicated for treatment of anteromedial
osteoarthritis of the knee. This arthritis
involves primarily the medial compartment of
the knee with joint space narrowing seen on
X-rays. The lateral compartment and patella
are usually not arthritic in this condition. The
Oxford differs from other partial knees in that
it has a mobile UHMWPE bearing which
duplicates normal knee kinematics.
Arthritis
• Defined as inflammation of
the joint
• Number one cause of disability in
the United States1
• More than 100 different types
• Two primary types
– Rheumatoid
– Osteoarthritis
Rheumatoid Arthritis
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Inflammatory
Diagnosed at younger ages than osteoarthritis
Can affect multiple joints at one time
Excess synovial fluid
Cartilage destruction
Osteoarthritis
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Degenerative joint disease
Most common form of arthritis
Wear and tear condition
Develops over time
– Overuse, injury or repetitive movement
– Developmental disorders
• Results in pain, stiffness
Symptoms of Osteoarthritis2
• Pain
• Stiffness
• Grating or “catching”
sensation during joint
movement
• Bony growths at the
margins of affected joints
X-Rays
• Helps determine severity of joint damage
• Cannot see cartilage on an X-ray
• Space on normal X-ray is healthy cartilage
Healthy X-ray
• Space shows healthy
cartilage
Osteoarthritis X-ray
• Joint space narrowing
• Abnormal bone formation
– “spurs”
• Joint deformity
– Bowleg
– Knock-knee
• A manageable,
treatable condition
When to Consider Joint Replacement
• Conservative non-operative treatments fail to
provide adequate pain relief
• Diminished quality of life
• Diminished joint function
Joint Replacement
• Also called “arthroplasty”
• Implants to resurface damaged bone and
cartilage
• Metal alloy and durable plastic
• Traditional vs. min. invasive with Oxford®
Partial Knee
Traditional Total Knee Replacement
• Resurfaces damaged cartilage on:
– End of femur
– Top of tibia
– Back of patella
• Incision between six and eight inches long
Primary Knee Components
Femoral Component
Polyethylene Bearing
Tibial Tray
Minimally Invasive Knee Replacement
• Potential advantages to traditional knee
replacement
– Healthy muscles and tissues preserved
• May be through a shorter incision
– Less blood loss
– Less tissue damage
• Not all patients are candidates
Minimally Invasive vs. Traditional Incisions
Minimally Invasive Incision
Traditional Incision
Minimally Invasive Partial Knee Replacement
• Replaces one compartment of the knee
• Knee cartilage resurfaced
– Metal alloy and polyethylene (plastic) components
• Instrumentation for minimally invasive
technique to help preserve healthy tissue
Oxford Partial Knee Components
Femoral Component
Polyethylene
Bearing
Tibial Tray
Oxford® Partial Knee Animation
Oxford® Partial Knee Implant
• Only mobile-bearing partial knee in U.S.
– Mobile plastic bearing moves with knee
motions
– Mobile bearing helps limit forces to help
avoid loosening4,5
• One clinical study yielded a 94%
success rate at 10 years and an
89% success rate at 20 years6
• There is no specific expected survivorship
for joint replacement
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Examples of Potential Complications of
Total Joint Replacement,
Any of Which Can Lead to Revision Surgery
Infection
Blood clots
Implant breakage
Malalignment
Wear
Loosening
Dislocation
No implant will last forever
Complications Affecting Outcome & Longevity
• Malalignment of implants
- Very dependent on surgical technique and
surgeon’s skill level
- Can be prevented with Signature cutting
blocks and guides
Signature ™ Personalized Patient Care
Signature ™ System
• Patient-specific femoral and tibial positioning
guides (not implanted) used for instrument
placement to remove damaged bone and
cartilage
• Developed from MRI Scan
• Allows for personalized instrumentation for
implant positioning
Before Surgery
• Traditional
– X-rays to plan
implant size
• Signature™ System
– MRI Scan to plan
surgery
• Digital, interactive
planning software
– Plans implant size and
placement before
surgery
Pre-op MRI/CT Scan
• About 20 minutes for
MRI scan
• Scan of hip,
knee and ankle
• Head stays outside
of machine
MRI
The Surgical Procedure
• Signature
– Patient-specific Guides
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Unique to every patient
Placed directly on bone/cartilage
Position pins for cut blocks
Cut blocks guide removal of damaged bone and
cartilage
Surgical Instrumentation
Traditional
Signature™ System
Signature™ System Benefits
• Does not invade the bone canal
• Fewer surgical instruments than traditional
partial knee replacement
• Allows for personalized instrumentation for
placement of the Oxford® Partial Knee implant
• Reduces the incidence of malaligned
components do to surgeon error
• Implant alignment optimized for that patient
Value of Joint Replacement
• Total joint replacement can save an individual
as much as $68,000 (total knee replacement)
to $180,000 (total hip replacement) in medical
costs over the life of the average total joint
recipient as compared to non‐surgical
treatment.4,5
Success of Total Joint Replacement
• Every year, over 1,000,000 people in the
United States have joint replacement
• Joint replacement treats debilitating pain and
deformity from various forms of arthritis
Closing
• A proper diagnosis from an orthopedic
surgeon can help identify cause of joint pain
• Many conservative treatments available
• Arthritis can be treated
• New surgical treatments also now available
with joint replacement implants with
improved function and longevity
References
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Centers for Disease Control and Prevention
http://www.cdc.gov/chronicdisease/resources/publications/AAG/arthritis.htm
The Arthritis Foundation http://www.arthritis.org/rheumatoid-arthritis.php
Vanguard Complete Knee System Package Insert http://www.biomet.com/orthopedics/getFile.cfm?id=2171&rt=inline
Argenson, J. et al. Polyethylene Wear in Meniscal Knee Replacement. A One to Nine-year Retrieval Analysis of the Oxford
Knee. Journal of Bone and Joint Surgery [Br]. 74 B:228–32, 1992.
Psychoyios, V. et al. Wear of Congruent Meniscal Bearings in Unicompartmental Knee Arthroplasty—A Retrieval Study of
16 Specimens. Journal of Bone and Joint Surgery [Br]. 80-B:976–82,1998.
Price, A. and Svard, U. A Second Decade Lifetable Survival Analysis of the Oxford Unicompartmental Knee Arthroplasty.
Clinical Orthopaedics and Related Research. Published Online 13 August 2010
AAOS. http://orthoinfo.aaos.org/topic.cfm?topic=A00233
Chang RW, Pellissier, JM, Hazen GB, “A Cost‐effective Analysis of Total Hip Arthroplasty for Osteoarthritis of the Hip,”
Journal of the American Medical Association (JAMA), Vol. 275, No.11, 1996, pp. 858‐865. (Figures apply to average 60
year old patient and adjusted for inflation.)
Questions
Thank You