Biomechanical comparison of kyphoplasty versus a titanium mesh implant with cement for stabilization of vertebral compression fractures.
METHODS
In vitro biomechanical investigation.


OBJECTIVE
To evaluate differences in biomechanical stability of vertebral compression fractures repaired using balloon kyphoplasty versus a titanium mesh implant.


BACKGROUND
Vertebral compression fractures may be stabilized using an expandable balloon followed by cement injection. There are small but finite risks of endplate fracture and cement extravasation with this procedure. Alternative techniques may affect cement injection volumes, height maintenance, and biomechanical stability but require investigation.


METHODS
Four male human cadaveric spines from T2 to L5 were used in this study. After determining bone mineral density, individual vertebral bodies were dissected and inspected for previous fractures or additional exclusion criteria. In the remaining vertebral bodies (n=48) anterior wedge fractures were created using a materials testing machine. Fractured vertebral bodies were systematically randomized to be repaired either with balloon kyphoplasty or with titanium mesh implant and polymethylmethacrylate bone cement, using image intensified fluoroscopy. Anterior vertebral body height (cm) was measured initially, after mechanically creating an anterior wedge fracture, after repairing the compression fracture with either technique, and after recompressing the vertebral body following a 24-hour cement polymerization period. Data for cement injection volume (mL) and height maintained following testing (cm) were compared between repair groups using a 1-way analysis of variance (P<0.05). Data for stiffness (N/mm), yield load (N), and ultimate load (N) were compared between intact bodies and repaired bodies using a 2-way analysis of variance (P<0.05).


RESULTS
There was significantly less cement injected (P<0.001) and significantly greater height maintained (P<0.025) with the titanium implant group compared to the kyphoplasty group. There were no significant differences in biomechanical stability between the 2 groups (P>0.05).


CONCLUSIONS
The titanium implant was biomechanically equivalent to the kyphoplasty repair while necessitating less cement and providing greater height maintenance in vitro. Improvements in pain and function could not be specifically addressed in this in vitro study and should be evaluated in a clinical case series.
Upasani
Vidyadhar V
VV
Department of Orthopaedic Surgery, University of California San Diego, and Orthopedic Biomechanics Research Center, Rady Children's Hospital and Health Center, San Diego, CA, USA.
Robertson
Claire
C
Lee
Deborah
D
Tomlinson
Tucker
T
Mahar
Andrew T
AT
D000368:Aged; D001696:Biomechanical Phenomena; D001843:Bone Cements; D002102:Cadaver; D004867:Equipment Design; D005592:Fracture Fixation / Q000295:instrumentation*; D050815:Fractures, Compression / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D058498:Kyphoplasty; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000293:injuries / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009984:Orthopedic Fixation Devices; D019904:Polymethyl Methacrylate; D016103:Spinal Fractures / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000293:injuries / Q000503:physiopathology / Q000601:surgery*; D014025:Titanium; D014057:Tomography, X-Ray Computed; D016474:Weight-Bearing
D001843:Bone Cements; D019904:Polymethyl Methacrylate; D014025:Titanium