Survivorship analysis of Cotrel-Dubousset instrumentation in idiopathic scoliosis

Abstract

IntroductionThe outcome of treatment for idiopathic scoliosis is usually assessed by radiologic study, to determine the angular correction obtained, and by analysis of the clinical results. Another datum of interest, particularly regarding vertebral implants, is the incidence of reoperations. From the patient's viewpoint, an implant that achieves excellent correction but is very likely to require a second operation may not be considered satisfactory. The appropriate statistical method for evaluating this event is survivorship analysis, which allows one to determine the true reoperation rate and to predict the probability of reoperation in the long Abstract This study presents a survivorship analysis of Cotrel-Dubousset instrumentation in the surgical treatment of idiopathic scoliosis. Between 1987 and 1995, a total of 133 patients with idiopathic scoliosis received posterior spine fusion and instrumentation with the CD system at our center. The patients' mean age at surgery was 16.5 years (range 11-43 years). The magnitude of the thoracic scoliosis averaged 62.7°(range 40°-125°) and that of the lumbar curve was 58.8°(range 40°-100°). On average, 12.2 segments were fused (range 8-17) and, excluding the rods, 14.1 implants were set for each patient (range 10-21). Survivorship analysis was carried out using the Kaplan-Meier method. Implant removal was considered the terminal event, or "death". The effect of several variables on survival rate was determined with the Cox regression method. The patients remained in the study for 56.7 months (range 2-120 months). One-hundred and ten patients were withdrawn ("censored"): 90 "alive" (did not require repeat surgery and attended followup control in 1997) and 20 "lost" (did not attend control in 1997). Twenty-three patients attained the terminal event of implant removal for a variety of reasons: acute infection (three cases), late infection (ten cases), implant failure requiring revision (six cases) and local pain (four cases). The survival rate was 95.5% at 3 months, 94.7% at 6 months, 93.9% at 1 year, 91.5% at 2 years, 82.2% at 5 years and 76.5% at 10 years. The magnitude of the curves, total number of implants and number of fused segments did not correlate with survival probability. A positive correlation was found between survival rate and correction loss between surgery and last control. A survival rate of 76.5% at 10 years is unexpectedly low. Current data suggest that the incapacity to maintain correction after initial surgery plays a major roll in the long-term evolution of CotrelDubousset instrumentation.

Surgery of lumbar and thoracolumbar scolioses in adults over 50. Morbidity and survival in a multicenter retrospective cohort of 180 patients with a mean follow-up of 4.5 years

“…To our knowledge, only two studies have evaluated this variable, although it could be extremely important to help the patient and the surgical team make a decision. In a series of 133 adolescents followed for a mean 16.5 years, Bagot et al [10] evaluated the risk of undergoing a second operation (for whatever the cause) as 6.1% at 1 year, 17.8% at 5 years and 23.5% at 10 years. For Mok et al, the risk of undergoing a second operation in adults was 13.6% at 1 year 12.8% at 2 years and 14.8% at 3 years.…”

Metal levels in corrosion of spinal implants

“…Although theoretically these instrumentations are necessary only until arthrodesis is achieved, most of them are not removed. In fact, survivorship analyses reveal that approximately 80% of these remain in situ 10 years after the initial surgery [3].…”

Prospective multicenter assessment of risk factors for rod fracture following surgery for adult spinal deformity

“…Although data thus far seem to indicate that selected adults with spinal deformity do have significant potential for improvement with surgical treatment, overall complication rates remain high and represent areas for continued improvement 7,8,32,[39][40][41][42][43] Despite great advances, an important source of complications and patient morbidity remains the inherent limitations of the durability of spinal implants. 1,3,4,6,[13][14][15][16][17][19][20][21]23,[25][26][27]30,32,33,38,[44][45][46][47]50,51 Although development of rod fracture may have significant consequences for patients, including pain, loss of deformity correction, and the need for revision surgery, the literature regarding rod fracture remains relatively limited. 1,4,9,11,15,19,23,29,38,49,51,52 Previous reports discussing rod fracture have...…”

“…1,3,4,6,[13][14][15][16][17][19][20][21]23,[25][26][27]30,32,33,38,[44][45][46][47]50,51 Although development of rod fracture may have significant consequences for patients, including pain, loss of deformity correction, and the need for revision surgery, the literature regarding rod fracture remains relatively limited. 1,4,9,11,15,19,23,29,38,49,51,52 Previous reports discussing rod fracture have many limitations, including retrospective design, inclusion of patients from only a single surgeon's cases or from a single institution, or lack of details regarding the specific type or composition of instrumentation. In addition, most previous series lack sufficient numbers of patients to enable a meaningful analysis of the subset with rod fracture.…”