THE MECHANICAL STABILITY OF ALLODERM FOR MYRINGOPLASTY

Ian Scott

Medical BiophysicsApril 7th, 2010

The Middle Ear

The function of the middle ear is to transfer acoustic energy from air in the ear canal to the fluid within the cochlea

Myringoplasty

• Acute infections of the middle ear are extremely common, especially among children and infants

• These infections can lead to perforations of the eardrum result of fluid and pressure build up

• Myringoplasty or Type 1 tympanoplasty, is the reconstruction of the eardrum, and is a very common surgery occurring in 5.4/10,000 in a population

Graft Materials

• Autograft– Cartillage– Fascia

• Allograft– Alloderm

Advantages of AlloDerm

• Decreased operating room time– Eliminates need for additional incisions

• Decreased risk of morbidity• Allows for surgery when autologous tissue

supply is exhausted– Revision myringoplasty surgeries are often required

Alloderm

• Acellular cadaveric tissue made by LifeCell Corp (Branchburg, NJ)

• Treated with a decellularizing agent eliminating the possibility of rejection

• Main structural components form a scaffolding

Functional Requirements

• Mechanically stable in presence of large pressures

• Similar vibratory characteristics to the eardrum

• Similar Young`s modulus and thickness to the eardrum

Objective

• Measure the response of AlloDerm to large static pressures up to 4kPa.

Methods

Results

Fig. Pressure deformation curves for varying static pressures

Results

Discussion

• AlloDerm showed stability up to 4kPa as required

• Non-linear relationship shown between static pressure and deformation

Conclusion

• AlloDerm is stable up to 4kPa of applied static pressure

• A non-linear relationship is shown between applied static pressure and deformation

Future Work

• Test on multiple samples to quantify variability in response

• Measure the vibratory characteristics in application to sound transfer

• Find Young`s modulus through the use of indentation tests to verify the required ``stiffness``

Acknowledgements

• Supervisor– Dr Hanif Ladak– Dr Sumit Agrawal

• The Lab– Xiaochuan Ma– Govind Rehal