A retrospective review of early outcomes of balloon kyphoplasty

Abstract

Steven R. Garfin, MD, San Diego, CA, USABackground context: An estimated 275,000 vertebral body compression fractures (VCFs) secondary to osteopenia, and refractory to medical management, occur in the United States each year. The deformity caused by VCFs is associated with chronic pain, impaired physical functioning, reduced quality of life, restrictive airway disease and increased mortality. This is a retrospective chart review of outcomes of inflatable bone tamp reduction and internal fixation using polymethylmethacrylate (PMMA).Methods: Vertebral body height was measured from X-rays from all patients treated by the authors (n=451). The point of greatest height loss was measured, as was that at a comparable location in the closest normal vertebral body. The height of the fractured vertebral body was divided by the height of the normal vertebral body to calculate the percent estimated height before treatment. After treatment, the same location was measured in the treated and nearby vertebral body, to calculate the estimated percent height after treatment. The results were stratified by duration of symptoms at diagnosis, before or after 3 months. The percent lost height restored was determined by: (percent estimated height before fracture minus percent estimated height after fracture)/(1 − percent estimate height after treatment). Reviewing the use of pain medication assessed reduction in pain. Institutional variations in these determinations were compared with the other centers performing kyphoplasty. The potential for inducing adjacent level fracture was assayed by determining the number of adjacent level fractures before treatment and then the number of new fractures that were adjacent to previously treated fractures.Results: A total of 2,194 fractures were treated (T4=3, T5=25, T6=48, T7=106, T8=114, T9=117, T10=102, T11=174, T12=333, L1=365, L2=249, L3=241, L4=183, L5=85, L6=1) in 1,439 patients in the United States from September 1998 through November 2000. Seventy-five percent were women. The average age was 73.5 years (range, 19 to 99 years). In fractures where the duration of symptoms at the initial visit was under 3 months, the average fractured vertebral body height was 71% before treatment and 92% after treatment (p<.002). In fractures over 3 months, the average fractured vertebral body height was 74% before treatment and 84% after treatment (p<.05). The average lost height restored for all fractures was 57%. Ninety percent of patients returned to prefracture pain medication (most often nonsteroidal anti-inflammatory drugs for arthritic type complaints) levels by 2 weeks. Major complications included three postoperative thoracic-level parapareses related to instrument insertion through the medial wall seventh pedicle with cord injuries. One patient had kyphoplasty performed while on anticoagulants and developed paraparesis and an epidural hematoma, which recovered completely after surgical decompression. There was one cement embolus without breathing consequences and a postoperative ileus caused by retroperitoneal bleeding in a patient on warfarin sodium (Coumadin; DuPont Pharmaceuticals Company, Wilmington, DE, USA). The serious adverse event rate is 0.2% per fracture and 0.4% per patient. Unrelated serious adverse events perioperatively included two myocardial infarctions related to overhydration, during the procedure, and two non–procedure-related perioperative deaths (cancer and coronary artery disease related). In patients with more than one fracture before their first kyphoplasty procedures, 63% of fractures not yet treated were adjacent. In 46 patients who returned for additional treatment of 139 fractures, 30% of the new fractures were adjacent to previously treated fractures. The results were nearly identical at each center, independent of physician.Conclusion: Kyphoplasty is a safe and effective treatment option for patients with painful VCF secondary to osteopenia. Height restoration was most improved if treatment occurred before 3 months from fracture, but some height restoration was obtained after 3 months. Comparing adjacent fractures in the untreated patients with the 2% of treated patients returning for additional kyphoplasty procedures does not indicate that kyphoplasty increases the rate of adjacent fracture. There was a remarkable consistency of treatment outcomes in the multicenter study. The four neurologic complications occurred in the first 100 fractures. Technique adjustments were made, and none have occurred since. (PMMA is approved by the Food and Drug Administration for long bones and joints. It is off-label for use in the spine.)