Lower Back Pain – Fusion 2

LBP-fusion 2
Operative Treatment

– much controversy still exists about what actually constitutes the best operative treatment

Posterolateral Arthrodesis
– most commonly performed +/- internal fixation.
Pedicle Screw Instrumentation
– from the FDA panel in 1994, a meta-analysis concluded that posterolateral fusion rates are enhanced by adjunctive spinal instrumentation (p=.08) with no differences between control devices and pedicle screw devices (p=.19).
– Yuan, 1994 – retrospective analysis of 2684 patients – significantly higher rate of fusion in those with pedicle screws.

Lumbar Interbody Arthrodesis

– those that advocate this technique generally consider the disc to be the primary source or pain and use the terms “discogenic pain, symptomatic annular tear, and internal disc disruption”. Excision of the disc and interbody arthrodesis is thought to remove the source of pain an prevent motion.

PLIFs
– not much out there on validated patient-outcome measures, but good-excellent results are seen in 80-90%.

Anterior Interbody Fusion
– allows for more complete excision of the disc
? what are they fusing it with?

Interbody Fusion Cages
– autologous nonstructural cancellous bone graft may migrate or collapse; these cages provide immediate support. Two major studies have indicated high fusion rates (Ray-TFC device – Ray, Spine, 1997; and BAK – Kuslich, Spine 1998.)

Circumferential Arthrodesis
– in theory, eliminates all potential sources of pain in anterior and posterior structures (assuming that we understand what causes back pain….)
– it has been observed that persistent back pain in those with a posterior arthrodesis is sometimes relieved after an additional anterior discectomy…
– not alot of literature yet…

Thoughts….

Well, another addition to the literature, with not much to come away with in terms of management. I think the main things to note are
1. on the subject of etiology, it is still not understood well; the discs are probably where most of the money is, but the facets may also play a role.
2. segmental instability is different than discogenic pain, and is also, rare.
3. discography can be used, but must be interpreted with caution; the addition of CT scan and/or MRI is helpful.
4. nonoperative treatment has been studied, not altogether in the most scientific fashion either. NSAIDS and muscle relaxants are good for acute pain; prolonged bedrest is bad. Exercises, traction, acupuncture, braces, TENS, and spinal manipulation – all have been sort of studied, with variable success.
5. the operative strategy is not clear. Pedicle screws seem to increase fusion rates, but weakly. The role of cages and 360 fusions will become more clear in the future, as the present literature is limited.