Current & Recent Research Projects

• Evaluation of absorbable Synthes cervical cage in a caprine model, time zero and longitudinal follow-up
• Maverick total disk replacement:
  • Biomechanical performance tolerance envelope
  • Lumbar facet loads and strains following implantation
  • Analysis of Maverick placement vs. arthrodesis
• Biomechanical comparison of Medtronic titanium vs. PEEK posterior rods for pedicle screw fixation
• Evaluation of tensile strength and effects of biodegradation of xenograft material for rotator cuff and tendon replacement
• Affects of torsional torque on intradiscal pressure and disc height in the human lumbar spine
• Evaluation of Optimesh for treatment of vertebral compression fractures and affects on adjacent levels
• Use of anterior or antero-lateral plating following ALIF vs. augmentation with pedicle screw fixation.
• Investigation of forces applied over the cervicothoracic and thoracolumbar transitional zones of the human spine
• In vitro model of subsidence following placement of anterior cervical cages.

Laboratory Patents & Pending Patents

• Prostheses for spine discs and fusion capability
• Prostheses for spine facets
• Multi-purpose irrigator
• Bone Fusion Material Compressor and Method of Use
• Antisubsidence, anti-translocation, lag, cervical plate with interface visualization
• Interconnected Porosity in Materials

Recent Publications

Rapoff AJ, Johnson WM, Venkataraman S. Transverse plane shear test fixture for total knee systems. Experimental Techniques 27 (3): 37-39 May-Jun 2003.

Rapoff AJ, Johnson WM, Handel J, Woo R. Interbody allograft in a skeletally immature spine model. European Spine Journal 12 (3): 307-313 Jun 2003.

Rapoff AJ, Conrad BP, Johnson WM, Cordista A, Rechtine GR. Load sharing in Premier and Zephir anterior cervical plates. Spine 28 (24): 2648-2650 Dec 15 2003 (invited paper in Cervical Spine Research Society Specialty Issue)

Rapoff AJ, Rinaldi RG, Johnson WM, Venkataraman S, Daegling D. Heterogeneous anisotropic elastic properties in a Macaca fascicularis mandible. American Journal of Physical Anthropology : 174-175 Suppl. 36 2003

Agazzi S, van Loveren H, Papangelou C, Yantzer BK, Trahan C, Johnson WM. Cervical interbody implant testing in the caprine model: a surgical and morphometrical rationale for choice of an appropriate level. Neurosurgery (in press)

Johnson WM, Rapoff AJ. Microindentation in Bone: hardness variation with five independent variables. Journal of Material Science: Materials in Medicine. (in press)

Yantzer, B., Freeman, T., Lee, W., Nichols, T., Inamasu, J., Guiot, B., Johnson, W. Torsion-Induced Pressure Distribution Changes in Human Intervertebral Discs: An In Vitro Study. Spine (in press)

Contact Info

Mailing address:
Department of Neurosurgery & Brain Repair
2 Tampa General Circle
Tampa, FL 33606
Phone: 813-259-0965
FAX: 813-259-0858