Setting of hardenable bone substitute
The invention relates to hardenable ceramic bone substitute compositions having improved setting, powders for such compositions and methods for their manufacture and use in medical treatment. More specifically the invention relates to hardenable bone substitute powder and hardenable bone substitute paste with improved setting properties, comprising calcium sulfate and heat-treated hydroxyapatite (passivated HA), which bone substitute is suitable for treatment of disorders of supportive tissue such as bone loss, bone fracture, bone trauma and osteomyelitis.
1. A method for preparing a composition consisting of a sintered, micronized, and passivated crystalline hydroxyapatite powder (pHA) including the steps of:
a) providing a powder consisting of sintered and micronized crystalline hydroxyapatite (raw HA powder) with the chemical formula (Ca 10 (PO 4 ) 6 (OH) 2 ), wherein the raw HA powder has a crystalline content of >90%, a particle size below 200 μm (D(v,0.99)), and a specific surface area below 20 m 2 /g (BET),
b) heating the composition consisting of the raw HA powder to a temperature between 300 and 900° C. for between 10 minutes and 10 hours to obtain the composition consisting of the sintered, micronized, and passivated crystalline hydroxyapatite powder (pHA).
2. A method according to claim 1 , wherein the heating step b) comprises heating composition consisting of the sintered and micronized crystalline hydroxyapatite (raw HA) powder to a temperature between 300 and 600° C. for 1 to 4 hours.
3. A method according to claim 1 , wherein providing the powder consisting of sintered and micronized crystalline hydroxyapatite (raw HA powder) in step a) comprises producing the raw powder by:
1) sintering hydroxyapatite at a temperature above 900° C., and
2) micronizing the sintered hydroxyapatite (HA) to obtain said raw HA powder.
4. A method according to claim 3 , comprising sintering hydroxyapatite at a temperature between 900 and 1350° C.
5. A method according to claim 1 , wherein the raw HA powder has a crystalline content of 95% or more.
6. A method according to claim 1 , wherein the raw HA powder has a crystalline content of 99%.
7. A method according to claim 1 , wherein the raw HA powder has a particle size of less than 50 μm (D(v,0.99)).
8. A method according to claim 1 , wherein the raw HA powder has a specific surface area below 10 m 2 /g (BET).