Unicompartmental Arthroplasty John Goodfellow Nuffield Orthopaedic Centre, Oxford

Anteromedial Osteoarthritis (30% of OA knees)

Fixed Bearing UKR Wear inescapable Incongruous Thin polyethylene Catastrophic failure

Meniscal function

Phase

Polyethylene Wear Average penetration rate 0.03mm per year Average time for 1mm penetration 33 years 10 year retrieval

Indications Criteria Antero-medial OA Intact ACL Full thickness lateral Correctable varus FFD less than 15° 1 in 3 OA knees Not Contraindications Patello-femoral joint Chondrocalcinosis Obesity Age Activity

UKR - Designer’s series 10 year survival 98% Murray et al JBJS 1998

Svard & Price (AAOS 2006) 20 yr survival 92% CI yr 90% Good or Excellent HSS (n=187)

Minimally Invasive Surgery

MIS results – Early Recovery Less Bleeding Lower Morbidity Shorter Hospital Stay Quicker Flexion Time to recovery: 3x faster than TKR (p<0.001) 2x faster than open UKR (p<0.001)

National Registers Measured by revision, failure rate of UKR at 10yrs is approx x 2 TKR National failure rates of UKR are higher than reports from Specialist Centres Failure rates of UKR vary with the experience of the surgeon

Dependence on Surgical Experience (Roberttson et al)

Instructional Courses To diminish the ‘learning curve’ To teach indications To improve surgical technique