2008/07/23

A. Grubl et al JBJS (B), Aug 2006,

 Polyethylene debris, wear particles  peri- prosthetic osteolysis  long-term failure  Change bearing surfaces  ceramic / metal

Co-Cr-Mo

 Al 2 O 3 ( 氧化鋁 )

 THR without cement in 100 consecutive patients  50 patients  metal-on-metal articulation,  50 patients  ceramic-on-polyethylene bearing  Metal particles: cobalt and chromium ions ↑

 P Sauvé; J Mountney; T Khan; J De Beer; et al  Journal of Bone and Joint Surgery; May 2007; 89,

 cobalt and chromium: 3~5 X ↑  Source of metal ions  Metal-on-metal articulations  3 patients: revision with metal-on-PE  the levels of metal ions were within the normal range

 Ring and other metal-on-metal THRs: early failure  some into fourth decade  polar bearing with sufficient clearance  good orientation of the component avoiding impingement  No polyethylene, no subsequent osteolysis  Wear rates between 40 and 100 times lower than those of metal-on-PE bearing surfaces !!

 Cobalt  Chromosomal abnormalities  potential for malignant change  Reduce osteoblastic activity  Inhibit the production of type-I collagen and osteocalcin and alkaline phosphatase activity  toxic to cultured human synovial fibroblasts  Peripheral blood CD+ T-cell counts are significantly reduced  Hypersensitivity  Women of child-bearing age  cobalt ions cross the placenta !!

 Aluminium:  Various neurological disorders  Alzheimer’s disease  Osteomalacia

 Prospective, randomized  Clinical trial  Ceramic-on-ceramic / metal-on-metal  Serum aluminium / cobalt levels

 Including:  Unilateral primary osteoarthritis  Avascular necrosis of the hip  Excluding:  Rheumatoid arthritis  Renal malfunction  Other metal implants

 Nov, 2000 to Feb, 2002  28 patients  Randomly to receive ceramic or metal bearing

 26 OA2 AVN  18 Female10 man  Mean age 62.2 years old. (32 to 81)  Mean BMI 28.1 (19.6 to 37.3)

Ceramic on ceramicMetal on metal Patient No.1513 Female : male8 : 710 : 3 Mean age58.2 (32 to 81)66.8 (56 to 78)

 All the same prosthesis except bearing surface  Ti-Al-Nb alloy (CSF-Gamma, Zimmer)  Ceramic / metal inlay  Ceramic inserts: Al 2 O 3  Metal inserts: Co-Cr-Mo

 Transgluteal approach (lateral)  supine  Intra-operation X-ray:  Cup inclination ≦ 45 degree

 Blood:  Needles: no cobalt  Glass tube  Pre-OP and 12 months after OP

 Serum Al and Co level  5100-ZL atomic absorption spectrometer (Perkin Elmer, Shelton, Connecticut)  Wavelengths: and nm  Lower limitation:  Al: 0.5 μ g/l; (define 0.25)  Co: 0.3 μ g/l; (define 0.15)

 Functional result  Harris hip score  University of California at Los Angeles activity score (UCLA)

 Pain  Limp  Support  Distance  Sitting  Enter public transporta tion  Stairs  Put on shoes  Deformity  ROM

 SAS  P value ≦ 0.05: statistically significant  Sign test for paired data

Ceramic on ceramicMetal on metal Pre-OP Post-OP Aluminium1.3 (0.25 to 8.4)1.9 (0.25 to 4.4) 1.1 (0.25 to 2.3)P =10.9 (0.25 to 3.9)P = Cobalt< (0.15 to 0.7)P= (0.5 to 10.5)P < Harris hip score58.4 (24.4 to 82.3)50.4 (15.1 to 71.4) 86.6 (41.5 to 100)85.1 (61.1 to 100) UCLA7 /10, 90% satisfied or very satisfied Mean inclination of cup 44.2° (34° to 54°)

 Cobalt and chromium ion ↑ : metal on metal THR  Aluminium: no increasing in metal-on-metal THR, but ceramic-on-ceramic ??

 Ceramic-on-ceramic bearings:  Low wear rate  High biocompatibility

 No evidence of systemic release of aluminium in the ceramic-on-ceramic or metal-on-metal groups  Serum cobalt ↑ in metal-on-metal group

 In vitro comparison of Metasul metal-on-metal and Cerasul ceramic-on-ceramic bearing  Stanmore Mk-III hip simulator  2~5 X 10 6 cycles  Similar abrasive wear behavior

 Prospective, randomised study  514 patients,  Alumina ceramic bearing vs. Co-Cr metal-on-PE bearing  Mid-term result: no significant difference in clinical performance

 In vivo  Ceramic-on-ceramic bearings are NOT associated with elevated levels of serum aluminium.  Cobalt level at one year was significant increasing in metal on metal group