MUHAMMAD USMAN SARWAROrthopedic Resident

Aga khan University Hospital,karachi.

Introduction Properties Different uses Prerequisite Modifiers Potential pitfalls and complications

History

The successful, long-term performance of orthopedic implants depends on: implant material, prosthesis design, biocompatibility of the component, wear of the articular surfaces, quality of the bone, and stability of fixation

Cemented anchorage achieves fixation with the help of a form-fitting cement that fills the gaps between the implant and the inner surface of the trabecular bone

Title of Dr Edward Haboush’s paper in 1951Journal Bulletin of the Hospital for Joint Diseases in 1953

Title page , John Charnely’s book published 17 years later in 1970

Sir John Charnley1 who is considered the founder of modern artificial joint replacement, developed the science and art of modern cementing technique in his laboratories in the late 1950s.

Despite a variety of cement less prostheses, cement fixation remains the gold standard, against which all forms of implant fixation techniques are assessed.

1-Charnley J. Anchorage of the femoral head prostheses of the shaft of the femur. J Bone Joint Surg Br. 1960; 42:28-30

Buchholz came up with the idea of adding an antibiotic to the cement to decrease the incidence of infection

Components Of Acrylic Bone Cement

Affects Mixing time Delivery of the cement Prosthesis insertion

It is important to adhere to the time schedules indicating the correlation of temperature to handling time.

High viscosity cements are sometimes pre- chilled for use with mixing systems for easier

mixing and prolonged working

Temperature is also important detrimental modifier.

High environmental temperature fasten polymerization and decrease working time.

or vice versa. Prechilling high-viscosity cements to slow

polymerization.◦ Long working time is also associated with porosity

, strength may be compromised.

Serve as a delivery vehicle for antibiotic

Act as a spacer, and be a filler of dead space

Infected joint arthroplasties and osteomyelitis

Open fractures with bone defects

Antibiotics eluted from surface, pores as well from micro cracks.

Antibiotic Heat stable Water soluble Powder form Least potential for allergy Sensitive to C/S Broad spectrum activity

Heat Stable antibiotics Aminoglycosides Cephalosporins Vancomycin Fusidic acid Quinolones Penicillin

Antibiotic loaded bone cement

Periprosthetic infection is the most feared complication in total hip and knee replacement.

The infection usually leads to a complete failure of the joint replacement, resulting in a long series of operative procedures, great discomfort for the patient and heavy costs.

Infections occur because of the high affinity of many germs to the surface of implants. Once settled, germs are less sensitive to antibiotics, as they are covered with a “slime(glycocalyx)” preventing them from action of antibiotics.

High local concentrations of antibiotics to be administered to the areas surrounding the implant, protecting the implant from the settling of germs.

Gentamycin,tobramycin are most commoly used other includes vancomycin ,cephalosporins

Gentamycin in liquid form has found to have adverse effects on mechanical properties.

Vancomycin generally should be reserved for MRSA

High concentration of antibiotic can be achieve in surrounding bone and scar tissue even in ischemic area.

Other uses ◦ Grade III open fractures with acute infections◦ Infected open fractures◦ Infected non unions◦ Acute and Chronic infections

Preoperative AP radiograph of an open IIIB forearm fracture. B, APradiograph demonstrating insertion antibiotic spacer radius defect followingthe third débridement, 96 hours after injury

SPINE

Frequently used mostly use limited to vertebral augmentation.

Galibert et al first reported successful use of PMMA in the management of haemangioma in vertebral body which apart from eradication of pain helped in the prevention of collapse.

Galibert P, Deramond H, Rosat P, Le Gars D: Preliminary note on thetreatment of vertebral angioma by percutaneous acrylic vertebroplasty[French]. Neurochirurgie 1987;33:166-168.

Same application was used later for mestatic disease of spine and myeloma to prevent collapse as well as pain and cord compromise.

Also used in the management of compression fracture because of osteoporosis.

J Am Acad Orthop Surg 2010;18: 297-305

It helps in early mobilization

Radiopacifiers are necessary to allow visualization of extravasation

Cement for long working phase is considered for vertebroplasty and short working phase is considered for khypoplasty

Properties of specific antibiotics Gentamycin Aminoglycoside Bactericidal, Dose-dependent killing curve Remains stable when exposed to

heat Soluble in water.

These characteristics make it especially suited for use in bone cement.

Clindamycin

Lincosamide group. Additionally active against some

anaerobic germs, such as peptostreptococci

Gentamycin and clindamycin

Combination known to have a bacterial effect on more than 90% of the bacteria common to infected arthroplasty cases

In the treatment of mixed bone infection cocktail of antibiotics can be used in the beads by sensitivities.

Antibiotics beads in management of surgical infections Am J Surg V 157 Apr 1989 p443

Elution of antibiotics Antibiotics elute out of cement very quickly

so their long term use of antibiotics is very limited.

Elution time of different antibiotics 3-6 Weeks

◦ Aminoglyicosides◦ Fusidic Acid◦ Quilolones◦ Ofloxacin

3-4 weeks◦ 3rd Generation Cephalosporins◦ Cefotaxime(Clafron)◦ Vancomycin

Appropriate serum levels should be obtained, if necessary.

One must be vigilant about toxic adverse effects of antibiotics.

Bone Bed Preparation

Careful preparation of the bone cavity and bone bed with high-pressure pulse lavage and brushing is essential for achieving an effective micro-interlock between the bone and the cement.

Clinical studies have shown that the use of high pressure pulse lavage reduces the risk of revision due to aseptic loosening.

Curing

Four phases Mixing Sticking Working Hardening

Temperature Mixing time Delivery of the cement Prosthesis insertion

It is important to adhere to the time schedules indicating the correlation of temperature to handling time.

High viscosity cements are sometimes pre- chilled for use with mixing systems for easier

mixing and prolonged working

Important detrimental modifier

High environmental temperature fasten polymerization and decrease working time or vice versa.

Air

Important detrimental effect Porosity Ultimate compressive strength and

Energy absorption capacity increase by 10%

to 15% after reducing porosity

Saha S, Pal S: Mechanical properties of bone cement: A review. J Biomed Mater Res 1984;18:435-462.

Aseptic loosening is considered to be result of monomer damage to bone.

End polymerization volumetric shrinkage of cement compromising bone cement interface.

Conflict between stiffness of cement and bone.

Cement particles were once considered biological cause of aseptic loosening◦ Charnley considered not cement rather mechanical

reason for aseptic loosening.◦ Wear particles are now seen as primary initiators of

the biological reactions in aseptic osteolysis

Ingham E, Fisher J. Biological reactions to wear debris in total joint replacement.Proc Inst Mech Eng [H] 2000;214:21-37.

Hypotension Hypoxia Pulmonary infarction Pulmonary embolism (marrow) Cardiopulmonary compromise.

Thank you.