Contemporary Solutions for Arthritis of the Knee

Arthritis affects over 70 million Americans •2nd only to heart disease in causing disability •1 million new patients diagnosed each year • Affects 50% of people 65yrs or older Source Centers for Disease and Prevention, 2004.

Osteoarthritis is most common form of Arthritis Rheumatoid arthritis Post-traumatic arthritis Inflammatory arthritis Septic arthritis All result in loss of joint cartilage Healthy Diseased

Factors that influence the onset of arthritis Heredity / Family history Age Weight Gender Trauma / Repetitive stress High impact sports Other illnesses Diseased compartment

The Knee is the #1 Joint Affected by Arthritis Large weight bearing joint Complex motion pattern Common site of injury Ligaments, meniscus

Presenting symptoms of Knee Arthritis Stiffness Swelling Deformity (“knocked-knee”/ “bow-legged”) Crepitus (clicking, crunching, grinding) PAIN Start-up Activity limiting Nighttime

Diagnostic Studies Weight-bearing Radiographs A/P, Lateral, Notch view Fairbanks Changes (subtle) Joint space narrowing Squaring of the condyles Osteophytes Sclerosis MRI Most helpful for ligaments and meniscal injury Mechanical symptoms “Symptoms don’t seem to fit”

Initial Conservative Treatments Tylenol® NSAID’s (non-steroidal anti-inflammatory drugs) Physical Therapy Activity Modification Weight Loss Nutritional Supplements

The first level of invasiveness: Therapeutic Injections Corticosteroid Inter-articular anti-inflammatory agent Short term symptomatic relief Viscoelastic Series Hyaluronic Acid injections: 3-5 shots Attempts to augment normal joint lubrication properties Potential for more long lasting relief (6mos-1yr)

The Orthopaedic Specialist When conservative treatments no longer resolve activity limiting pain caused by osteoarthritis then . . . Surgical and reconstructive treatments may be appropriate

Surgical Options for Knee Arthritis Arthroscopy Debridement Meniscectomy Chondroplasty Osteotomy Bone cut and re-aligned onto remaining good cartilage Arthroplasty (Joint Replacement) Uni-compartmental knee replacement (partial knee replacement) Tri-compartmental knee replacement (total knee replacement)

Arthroscopic Debridement “clean out” or “scrape bone” Somewhat unpredictable results 50 to 66 percent get relief for some period of time Best for patients with mechanical symptoms (catching, locking and giving out)

Knee Osteotomy Re-align weight-bearing axis through “good” cartilage Most popular before success of contemporary knee replacement Useful for patients too young, heavy or active for knee implants Early results acceptable, questionable durability

End-Stage Osteoarthritis  Knee Replacement Uni-compartmental Knee Replacement “Uni,” “partial replacement” or UKR Tri-compartmental Knee Replacement “total replacement” or TKR

Minimally Invasive Knee Replacement Same implants as traditional knee replacements Components Femoral Tibial Patellar

Minimally Invasive Knee Replacement Potential Benefits: Less trauma to the knee Less bleeding Less pain Cosmetically appealing (smaller scar) Shorter hospital stay Quicker recovery than traditional total knee replacement Potential Complications and Risks Factors that effect risks: Skill of the surgeon Age, weight and health of the patient Patient compliance

Total Knee Replacement Most common joint replaced First performed in 1968 Nearly 400,000 TKR’s performed per year in US

Total Knee Replacement Patient satisfaction typically 85-90% Relieves pain Restores mobility Durability well documented at ~90% survivorship @10yrs Improvements in materials and techniques continue to increase effectiveness Schai, P.A., T.S. Thornhill and R.D. Scott. "Total Knee Arthroplasty with the P.F.C. System: Results at a Minimum of Ten Years and Survivorship Analysis." JBJS Sept. 1998: 850-858.

TKR: Who’s a candidate? Many patients that could be helped by knee replacement don’t know about it or do not seek care Lack of knowledge Misconceptions Fear “Postoperative Patient Data”, DePuy Internal Study. Nov-Dec. 2003. Sample size: 80 patients How long do patients wait before they see their surgeon?

Important Patient Demographic Trends Over 65yr group is the most rapidly expanding segment of our population Increasing individual longevity will result in a greater number of individuals living long enough to be diagnosed with arthritis (Average age of today’s total knee replacement patient is 67yrs)

Important Patient Demographic Trends 36% of TKR patients are between ages 40-64 This group of younger patients requiring TKR is increasing Those individuals requiring treatment for their arthritis will need solutions with even greater durability

Common Misconceptions Delaying TKR Surgery Too Young—Components will “wear out” and have to be revised Too Active—Components will “wear out” prematurely and have to be revised Too Heavy— Stresses on components will cause them to “wear out” or “break”

Kinematics of a traditional (fixed-bearing) TKR Normal knee motion is a complex combination Flexion/extension Anterior/posterior translation Internal/external rotation Varus/valgus lift off

Leading Causes of TKR Failures Component loosens Surgical technique Infections Polyethylene component wears out What causes this wear? What can we do about it?

Addressing Polyethylene Wear Wear is affected by Implant design Implant materials Implant alignment (surgical technique)

Polyethylene Wear One of the leading causes of implant failure over time Osteolysis Early Revision Negative Effect/Perception of patient Decreased Range of Indications Implant design and materials chosen are two of the most significant things that can be done to minimize (or virtually eliminate) the effect

Implant Design & Materials Stress = Load/Area Area Stress Area Stress

Implant Design & Materials – continued Contact Stress Patches Overall applied stress (force) Surface contact area Limitation in contact area results in relatively high level of Polyethylene stress (wear) Sheer Fixed Bearing System Rotating Platform System

If Contact Stress is not Optimized Results in relatively high level of Polyethylene stress (wear)

If alignment is not optimized… 10° Predisposes to accelerated polyethylene wear

Today’s Implants The Goal of a TKR Implant Solutions Restore normal function of the knee Last as long as possible Solutions Fixed Bearing TKR System A Mobile Bearing/ Rotating Platform TKR System

Fixed Bearing TKR Systems Good clinical results Designs of Fixed Bearing systems may not optimize wear reduction Does not mimic all range of motion of the natural knee

The Rotating Platform Solution “Congruity with Mobility” Constraint forces minimized by allowing bearing rotation Articulates like the natural knee Full and normal range of motion Increased contact area results in reduced polyethylene stresses (wear) 94% reduction over Fixed Bearing Systems* Shear forces at implant-bone interface minimized Could minimize loosening Outstanding clinical results for over 25 years C.J. Bell, H.M.J. McEwen, P.I. Barnett, R. Farrar, M. Stone, J. Fisher, “Comparison of Wear in Fixed and Mobile-bearing Knee Designs,” Transactions of the 49th Annual Meeting of the Orthopaedic Research Society, New Orleans, La., 2003. H. Maars, D.C. Barton, R.A. Jones, I.M. Wards, J. Fisher, “Comparative Wear Under Four Different Tribological Conditions of Acetylend Enhanced Cross-Linked UHMWPE,” Journal of Materials Science: Materials in Medicine 10 (1999) 333-342. C.J. Bell, P.S. Walker, S. Sathasivam, P.A. Campbell, G. Blunn. “Differences in Wear Between Fixed-bearing and Mobile-bearing knees.” Transactions of the 45th Annual Meeting of the Orthopaedic Research Society, Anaheim Calif., 1999. P. Lewis; C. H. Rorarbeck, R.B. Bourne and P. Devane. “Posteromedial Tibial Polyethylene Failure in Total Knee Replacements.” CORR Feb. 1994: 11-17. A. Cadambi, G.A. Engh, K.A. Dwyer and T.N. Vinh. “Osteolysis of the Distal Femur After Total Knee Arthroplasty.” The Journal of Arthroplasty Dec. 1994: 579-594.

Advantages of a Rotating Platform Knee Replacement “Show me the Data” 94% wear reduction with Rotating Platform vs Fixed bearing Fig. 1 Average Wear Rate per Million Cycles C.J. Bell, H.M.J. McEwen, P.I. Barnett, R. Farrar, M. Stone, J. Fisher, “Comparison of Wear in Fixed and Mobile-bearing Knee Designs,” Transactions of the 49th Annual Meeting of the Orthopaedic Research Society, New Orleans, La., 2003. H. Maars, D.C. Barton, R.A. Jones, I.M. Wards, J. Fisher, “Comparative Wear Under Four Different Tribological Conditions of Acetylend Enhanced Cross-Linked UHMWPE,” Journal of Materials Science: Materials in Medicine 10 (1999) 333-342. C.J. Bell, P.S. Walker, S. Sathasivam, P.A. Campbell, G. Blunn. “Differences in Wear Between Fixed-bearing and Mobile-bearing knees.” Transactions of the 45th Annual Meeting of the Orthopaedic Research Society, Anaheim Calif., 1999. P. Lewis; C. H. Rorarbeck, R.B. Bourne and P. Devane. “Posteromedial Tibial Polyethylene Failure in Total Knee Replacements.” CORR Feb. 1994: 11-17. A. Cadambi, G.A. Engh, K.A. Dwyer and T.N. Vinh. “Osteolysis of the Distal Femur After Total Knee Arthroplasty.” The Journal of Arthroplasty Dec. 1994: 579-594. McNulty, ASTM,2002

Implant Alignment Self Aligning Q-Angle Less Stress on Quadriceps Reduced Lateral Release rate Reduced Bleeding Reduced Pain Improved Recovery Maximize Tibial Placement and Alignment Extensor Mechanism Aligns w/ the Trochlear Groove Promotes Patellar Tracking

Advantages of a Rotating Platform Knee Replacement “Show me the Data” Twenty year evaluation of rotating platform mobile bearing knee replacements Survivorship 97.7% at 16-20yr Buechel et al Clin Ortho 2001 Cemented rotating-platform total knee replacements 9-12yr follow-up 119 TKA’s, Survivorship 100% at 10yrs Callahan et al JBJS 2000

Contemporary Solutions for Arthritis of the Knee Summary The number of patients suffering from arthritis of the knee is steadily growing Of the patients suffering from knee arthritis nearly half may not seek treatment due to poor information or fear Patients seeking care are younger, more active and more demanding Total knee replacement is a reproducible, reliable and durable solution to end-stage knee arthritis

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