Age of Fracture and Clinical Outcomes of Percutaneous Vertebroplasty

Percutaneous vertebroplasty (PVP), first described in France in 1987 (1), is a therapeutic procedure performed for persistent pain or instability from osteoporotic or neoplastic vertebral compression fractures (VCFs). The clinical outcomes of pain severity, mobility, and analgesic requirement are commonly measured to evaluate the effectiveness of the procedure.

Eighty-four percent of VCFs are painful, with pain lasting 4–6 wk on average (2). A subgroup of patients with VCF experiences subacute or chronic pain that is refractory to conservative therapy, which usually consists of analgesic use, rest, and external bracing. Immobility makes these patients more susceptible to pneumonia, deep vein thrombosis, and pulmonary embolism (2). Immobilization also accelerates bone loss, which may contribute to further VCFs (2).

Some investigators consider the age of fracture an important predictor of expected pain relief after PVP. Reports of recent series detailing the efficacy of PVP have described only patients with VCFs less than 1–4 mo old (3–5); however, clinical outcomes after PVP have not been directly correlated with the age of fracture. We performed a retrospective chart review to determine whether clinical outcomes after PVP are influenced by the age of fracture at the time of the procedure.

Methods

Results

Discussion

Although PVP has been applied clinically for more than 10 y, the inclusion and exclusion criteria for percutaneous vertebroplasty performed for osteoporotic VCFs have varied widely in the case series reported in the English-language literature (3–5, 7–15). Although the subjective failure of conservative therapy generally is used as an indication for the procedure, the time from fracture to PVP ranges from 2 wk to at least several months (3–5, 7–15). One series included only patients who had received less than 1 mo of conservative therapy before vertebroplasty (3), and another report included only patients who had received at least 3 mo of conservative therapy, although this latter study excluded those with chronic back pain (11). To our knowledge, the effect of age of fracture on patient outcomes has not been specifically measured to date. We attempted to provide evidence for the effectiveness of PVP for VCFs of varying age or duration of symptoms.

Our results suggest that PVP in osteoporotic VCF is highly efficacious for pain relief and improvement of patient mobility across a wide range of fracture ages, as measured with the duration of symptoms referable to a VCF. PVP also is effective in reducing the requirement for analgesia, although this effect may be slightly blunted in patients who require narcotics before the procedure and in those who have older fractures. Some patients may become habituated to or dependent on a certain level of analgesia and thus respond less to PVP with regard to analgesic use. Also, expected improvement in patient mobility after PVP may be slightly limited in patients with lower preprocedural activity levels.

Several recent case series (3–5, 7–15) have reported significant or dramatic pain relief with PVP in as many as 90% of cases of osteoporotic VCFs. The mechanism of pain relief from PVP remains uncertain. The stabilization of microfractures, as well as vascular, chemical, and thermal factors, have been proposed as mechanisms (16). Findings of these case series also have suggested improvements in mobility and reductions in analgesic requirements as outcomes of vertebroplasty (3–5, 7–9, 11–15).

Our study is limited by its sample size and the selection and review biases inherent in many retrospective observational studies. In fact, patients in our practice with older fractures historically have been told that the efficacy of PVP may be less certain in patients with such fractures, and this practice may have resulted in the over-selection of only those patients with more severe symptoms among those with older VCFs. The accuracy and uniformity of data gathered retrospectively often are poorer than for data gained prospectively. We cannot be certain how the patients with more complete records selected for our cohort differ from patients who were not selected. Also, in our practice, most patients undergo radioisotope bone scanning or MR imaging to evaluate the age or state of healing of the compression fractures, to aid in patient selection for PVP. This practice limits the generalizability of our findings to centers where bone scanning or MR imaging is not performed as frequently. We report statistically significant improvements in pain, mobility, and analgesic use, but we had no control group for comparison. We cannot know the extent to which factors such as the placebo effect, regression to the mean, and natural history of the disease may have biased conclusions made from these data (17).

We inferred the ages of VCFs by using the duration of new, focal back pain that corresponded with a radiologically depicted fracture. Certainly, the accuracy and precision of this surrogate are unknown and probably limited. Patients seek treatment after having pain of a given duration, however, and the age or state of healing of a fracture often is inferred from the patient history and with imaging techniques, as it was in our study. The prediction of how patients with particular pain histories and imaging findings may respond to therapies, such as PVP, may have more clinical value than does the correlation of the often-unknowable exact fracture age with therapeutic outcomes.

Because of limitations in the patient records and sample size, we were restricted in the number of variables that we could gather and test. If we were developing a model for prediction in other patients, our logistic regression models would have tested more variables than would be advisable, given our sample size; thus, we limited the use of these models to hypothesis testing. Overfitting the models would have caused more concern if we used them in prediction.

Inclusion and exclusion criteria for PVP merit further study, preferably with prospective randomized trials with improved instruments for measuring outcomes. We expect that patient outcomes substantially depend on selection criteria, such as the state of healing of the fractures and preprocedural outcomes scores, as well as many other variables.

Conclusion

PVP is a highly efficacious therapy for pain relief and improvement in mobility, regardless of fracture age or duration of symptoms. PVP also is effective in reducing the requirement for analgesia, although this effect may be slightly blunted in patients with older fractures. In our practice, patient selection for PVP is not based on the age of VCF but largely on evidence of nonhealing on bone scans or MR images and the degree of persistent pain.