Cages Preferred Over Dowels for Spinal Fusion

For the last 10 years, spinal fusions have been done with titanium cages inserted into the disc space. The cages are filled with bone graft material. Bone fills in and around the cages during the healing process. This forms a solid spinal fusion.

In this study, researchers try using threaded bone dowels instead of cages. The dowels are made from freeze-dried cadaver bone. Cadaver bone comes from a body preserved after death for scientific use. The bone is taken from the femur (thigh bone) or tibia (lower leg bone).

Bone dowels have several theoretic advantages over metal cages. First, bone is more elastic than metal. It can transmit forces better. The bone will become a natural part of the fusion. Without the metal cages in the way, imaging studies can give a clearer view of the fusion site. And bone can be used when there is infection present.

All patients had an anterior interbody lumbar fusion (ALIF) procedure. This means the operation was done from the front of the body. The same surgeon did everyone's surgery. Everyone was followed for at least two years.

The results showed that the fusion rates are better with titanium cages. Bone dowels can be used successfully but clinical success is not as good. Titanium cages bear higher loads than bone dowels.

Bone dowels should not be used alone. The results are better if they are combined with metal screws or plates along the back of the spine. This instrumentation will help hold the spine stable until fusion takes place.

The authors also suggest that if the dowel cracks or breaks, then it should be replaced right away. A fusion cage should be used in its place.