Pedicle Screw Disease

  Pedicle screw, one of the great innovations in spinal implants since Harrington rod  for correction of scoliosis. It has been used successfully in treating spinal fracture, deformities, and spinal metastasis, thanks to its provided rigidity.  Pedicle screw is indispensable in some spinal disorders from top to bottom of the spine.

  But unfortunately, its use in lumbar degenerative disorders is anther story. Also, pedicle screw placement is a technically demanding procedure with a high complication rate. Let's take a look at U.S. FDA's ruling of pedicle screw in 1998:

``Warning: The safety and effectiveness of pedicle screw ..only for.. significant mechanical instability...degenerative spondylolisthesis with..neurologic impairment, fracture, dislocation, scoliosis, kyphosis, spinal tumor, and failed previous fusion (pseudarthrosis). The safety and effectiveness..for any other conditions are unknown.'' ``Precaution:..pedicle screw..performed only by experienced..surgeons with specific training..this is a technically demanding procedure presenting a risk of serious injury to the patient.'' 

 Globally, surgeons have used pedicle screw to an extent of indiscretion (excuse me, folks, I am not pointing the finger at you.)  especially at the degenerative lumbar spines.

12 years later, we have enough literature regarding complications of pedicle screw,  of varying severity in 54% of the patients:

1. deep infection: more than 4%. According to my associate, Dr. SH Chen, who once worked at a gigantic spine unit, he said the actual infection rate was around 6%, higher than the reported statistics; some were devastating, resulting in quadriparesis or paraplegia, even death.

2. permanent nerve root Injury: 2.3% . crippled.

3. Misplacement of screw: 11-20% , some were inside the spinal canal.

4. Back muscle injury: weakness of the back.

5. Late backache requiring screw removal: 23%

6. Adjacent segment disease (ASD):  16.5% at five years and 36.1% at ten years, requiring additional surgery.

The rate of symptomatic ASD is higher in patients with transpedicular instrumentation (12.2–18.5%) compared with patients fused with other forms of instrumentation or with no instrumentation (5.2–5.6%)

(Left) Deep infection after pedicle screw fixation, Wound Dehiscence .  Right: Pus flew out flooding all over the dura sac. (Courtesy of Dr. SH Chen)

Angulation of L1-2 level (ASD), fortunately no nerve injury. 62 years lady.

T12-L1 ASD, 70 years old male, crippled, underwent 4 spine surgeries in 2 years, including once for deep infection. T12-L1 ASD, screw penetrating the disc and all screws were loosened.

 

The sad and grim scientific evidences shown above indicate that we need to rethink the use of pedicle screw, particularly in degenerative lumbar vertebrae.

Note: I invented the term: Pedicle Screw Disease, all rights reserved (joke).