Current issues of ACP Journal Club are published in Annals of Internal Medicine


Chemonucleolysis and disk surgery for lumbar disk herniation

ACP J Club. 1992 Sept-Oct;117:44. doi:10.7326/ACPJC-1992-117-2-044

Source Citation

Muralikuttan KP, Hamilton A, Kernohan WG, Mollan RA, Adair IV. A prospective randomized trial of chemonucleolysis and conventional disc surgery in single level lumbar disc herniation. Spine. 1992 May;17:381-7.



To compare chemonucleolysis and conventional disk surgery for adults with lumbar disk herniation.


1-year randomized controlled trial.


An orthopedic center in a tertiary care hospital in Northern Ireland.


Adults with nerve root pain were included if they had not improved after 4 weeks of conservative treatment that included 2 weeks of bed rest, and if they had radiologically proven disk prolapse with signs of nerve root irritation, disk compression, or both. Excluded patients had other lumbar spinal disease, rapidly progressive neurologic deficits, drug allergies, diabetes mellitus, peripheral neuropathy, multiple disk herniations, or herniations at levels other than L4-5 or L5-S1. 92 patients (mean age, 38 y; range, 19 to 60 y; 55 men) were randomized. Follow-up was 94%.


46 patients received chemonucleolysis (sedation with local anesthesia and injection with 4000 pkat of chymopapain in 2 mL H2O). Patients were mobilized as pain allowed and returned home 4 to 8 days later. 46 patients received fenestration or limited laminectomy to excise the disk prolapse and clear the disk space. They had similar mobilization and returned home in 9 or 10 days.

Main outcome measures

Pain, measured with visual analog scales; disability; and psychological well being were assessed before treatment and 6 weeks, 3 months, and 1 year later. Re-operation rates and total costs were also measured.

Main results

No serious complications occurred. 9 patients in the injection group (21%) and 1 in the surgical group (2%) failed to improve and required surgery (P < 0.02). At 1 year only 31% of patients in the surgery group and 18% of patients in the chemonucleolysis group were completely free of pain. Both groups, however, had little residual nerve root irritation at 1 year. In the chemonucleolysis group, leg pain was greater at 3 months (P < 0.05), back pain was greater at 6 weeks (P < 0.05), and physical impairment was greater at 3 months (P < 0.01). At all other times the groups did not differ for disability, leg pain, back pain, physical impairment, or psychological scores, although the surgery group had better results on all of the outcome measures (6 wk and 3 mo). Total costs were 34% higher in the chemonucleolysis group.


Patients with disk herniation experience better short-term pain relief with conventional disk surgery than with chemonucleolysis.

Source of funding: Medical Research Council, United Kingdom.

Address for article reprint: Dr. K.P. Muralikuttan, Department of Orthopaedic Surgery, Queen's University of Belfast, Musgrave Park Hospital, Belfast BT9 7JB, Northern Ireland.


Graded Activity and Operant Conditioning for Low Back Pain

The common terminology "low-back pain" emphasizes pain rather than disability or handicap, a distinction that has not been productive. These 2 studies assess strategies to reduce the disability or handicap.

The sound methods of these studies minimize bias and ensure that the differences reported are real. The clinician, however, must evaluate whether the studies have clinical significance and whether they will actually benefit patients. In the study by Muralikuttan and colleagues a significant advantage of surgery over chemonucleolysis was identified at 6 weeks and 3 months but not at 1 year. The participation rate at both 6 weeks and 3 months was 80% (18 patients not assessed) compared with 96% assessed at 1 year. Unequal distribution between groups could account for the early differences reported or could have obscured greater differences. Clinically the differences observed seem borderline.

Although the groups did not differ after 1 year, composite scores for both treatments were improved over entry status with respect to disability, impairment, and leg pain. There was minimal improvement in psychological score and none for back pain. The latter reinforces the impression that such treatment may not substantially alter back pain.

The advantages of surgical treatment were clear: It was less expensive; the failure rate was less for those receiving surgery (2% vs. 21%; P = 0.02); and surgery might have prevented 4 of the 9 chemonucleolysis failures. Although not statistically significant, the proportion free from pain in the surgical group was higher at year end (31% vs. 18%). Is either treatment superior to conservative management? Perhaps it is in the short term. The classic study by Weber (1), with similar patients, showed better results for surgery over conservative management at 1 year and nonsignificant improvement at 4 years; the groups did not differ at 10 years.

The study by Lindström and colleagues involved a group of patients with the commonest back problem—nonspecific, mechanical low-back pain. Appropriately selected Volvo workers, off work for more than 8 weeks, were randomly assigned either to receive a complex management package or to be in a control group receiving standard medical care. A difference from other studies of activation was the use of operant conditioning techniques; for example, instead of exercising to tolerance (in which rest or time off is contingent on experiencing pain), a quota for each exercise was determined from the functional capacity test, and workplace visits and exercises were done based on specified increasing quotas (non-pain-contingent).

The activity program resulted in statistically and clinically significant short- and long-term benefits. These benefits are consistent with recent studies indicating that physical activity focused on a specific goal is effective in reducing back disability. It is not possible from the study report to isolate specific components of the intervention that may have been major determinants for the differences observed, but potentially powerful additions to graded activity included operant conditioning and direct involvement with the work and workplace. The latter could substantially influence earlier return to work. Although one cannot be sure which components of the intervention are crucial, it is clear that multidisciplinary, directed activation can reduce back disability.

Edward S. Gibson, MD
Dofasco Medical Centre Hamilton, Ontario