Survivorship analysis of DKS instrumentation in the treatment of spondylolisthesis

Risk factors for adjacent segment degeneration after surgical correction of degenerative lumbar scoliosis

BACKGROUND

Degenerative lumbar scoliosis surgery can lead to development of adjacent segment degeneration (ASD) after lumbar or thoracolumbar fusion. Its incidence, risk factors, morbidity and correlation between radiological and clinical symptoms of ASD have no consensus. We evaluated the correlation between the occurrence of radiologic adjacent segment disease and certain imperative parameters.

MATERIALS AND METHODS

98 patients who had undergone surgical correction and lumbar/thoracolumbar fusion with pedicle screw instrumentation for degenerative lumbar scoliosis with a minimum 5 year followup were included in the study. We evaluated the correlation between the occurrence of radiologic adjacent segment disease and imperative patient parameters like age at operation, sex, body mass index (BMI), medical comorbidities and bone mineral density (BMD). The radiological parameters taken into consideration were Cobb's angle, angle type, lumbar lordosis, pelvic incidence, intercristal line, preoperative existence of an ASD on plain radiograph and magnetic resonance imaging (MRI) and surgical parameters were number of the fusion level, decompression level, floating OP (interlumbar fusion excluding L5-S1 level) and posterolateral lumbar interbody fusion (PLIF). Clinical outcomes were assessed with the Visual Analogue Score (VAS) and Oswestry Disability Index (ODI).

RESULTS

ASD was present in 44 (44.9%) patients at an average period of 48.0 months (range 6-98 months). Factors related to occurrence of ASD were preoperative existence of disc degeneration (as revealed by MRI) and age at operation (P = 0.0001, 0.0364). There were no statistically significant differences between radiological adjacent segment degeneration and clinical results (VAS, P = 0.446; ODI, P = 0.531).

CONCLUSIONS

Patients over the age of 65 years and with preoperative disc degeneration (as revealed by plain radiograph and MRI) were at a higher risk of developing ASD.

Effects of lumbar arthrodesis on adjacent segments: differences between surgical techniques

STUDY DESIGN

A finite element analysis.

OBJECTIVE

To evaluate the differences between surgical techniques in terms of the effects of arthrodesis on adjacent segments.

SUMMARY OF BACKGROUND DATA

Augmentation with posterior rigid fixation combined with transpedicular screw insertion, which is one of the most popular techniques for lumbar arthrodesis, shows benefits in immediate stabilization and a higher fusion rate but is reportedly correlated with greater stress on adjacent segments. However, the increased stress on adjacent segments needs further evaluation because the differences of the effects on adjacent segments between surgical techniques, including anterior lumbar interbody fusion, posterior lumbar interbody fusion, and semirigid fixation, have not yet been determined.

METHODS

A finite element model of the human lumbar spine was developed. Three spinal segments (L2-L5) were used to investigate. The intact spinal model was validated by comparing it with previously reported models. Then, 4 arthrodesis models were analyzed and compared: (1) anterior lumbar interbody fusion model; (2) posterior lumbar interbody fusion model; (3) semirigid fixation model combined with posterior lumbar interbody fusion; and (4) rigid fixation model combined with posterior lumbar interbody fusion.

RESULTS

Among these 4 models, the rigid fixation model showed the greatest amount of stress, with increased intervertebral disc pressure and contact force of the facet joints of both upper and lower adjacent segments. The second highest stress levels were seen in the semirigid fixation model and the lowest stress levels were seen in the anterior lumbar interbody fusion model.

CONCLUSION

Although bony fusion had been completed, the effects of lumbar arthrodesis on adjacent segments could vary according to the surgical technique used for arthrodesis. Semirigid fixation combined with arthrodesis deserves careful consideration and further detailed study because it may cause less stress on adjacent segments than rigid fixation while maintaining the benefits of the latter procedure.

Incidence and prevalence of surgery at segments adjacent to a previous posterior lumbar arthrodesis

BACKGROUND CONTEXT

Adjacent segment disease (ASD) after lumbar spinal fusion has been an important reason behind the development of nonfusion stabilization technology. However, the incidence, prevalence, and factors contributing to adjacent segment degeneration in the lumbar spine remain unclear. A range of prevalence rates for ASD have been reported in the lumbar spinal literature, but the annual incidence has not been widely studied in this region. Conflicting reports exist regarding risk factors, especially fusion length.

PURPOSE

To determine the annual incidence and prevalence of further surgery for adjacent segment disease (SxASD) after posterior lumbar arthrodesis and examine possible risk factors.

STUDY DESIGN

Retrospective cohort study.

PATIENT SAMPLE

Nine hundred twelve patients who underwent 1,000 consecutive posterior lumbar interbody fusion procedures, with mean follow-up duration of 63 months (range, 5 months-16 years).

OUTCOME MEASURES

Further surgery for ASD or surgery-free survival.

METHODS

A postal and telephone survey. Follow-up rate: 91% of patients. The annual incidence and prevalence of ASD requiring further surgery were determined using Kaplan-Meier survivorship analysis. Cox proportional-hazards (Cox) regression was used for multivariate analysis of possible risk factors. Significance was set at p<.05.

RESULTS

Further surgery for ASD occurred following 130 of 1,000 or 13% of procedures at a mean time of 43 months (range, 2.3-162 months). The mean annual incidence of SxASD over the first 10 years, in all patients, was 2.5% (95% confidence interval [95% CI], 1.9-3.1) with prevalences of 13.6% and 22.2% at 5 and 10 years, respectively. Cox regression modeling found that the number of levels fused (p≤.0003), age of the patient, fusing to L5, and performing an additional laminectomy adjacent to a fusion all independently affect the risk of SxASD. The mean annual incidence figures in the first 10 years after a lumbar fusion were 1.7% (95% CI, 1.3-2.2) after fusion at single levels, 3.6% (2.1-5.2) after two levels, and 5.0% (3.3-6.7) after three and four levels. The 5- and 10-year prevalences were 9% and 16%, 17% and 31%, and 29% and 40% after single-, two-, and three-/four-level fusions, respectively. The risk of SxASD in patients younger than 45 years was one-quarter (95% CI, 10-64) the risk of patients older than 60 years (p=.003). A laminectomy adjacent to a fusion increases the relative risk by 2.4 times (95% CI, 1.1-5.2; p=.03). Stopping a fusion at L5 is associated with a 1.7-fold increased risk (95% CI, 1.2-2.4; p=.007) of SxASD compared with a fusion to S1, for fusions of the same length.

CONCLUSION

The overall annual incidence and predicted 10-year prevalence of further surgery for ASD after lumbar arthrodesis were 2.5% and 22.2%, respectively. These rates varied widely depending on the identified risk factors. Although young patients who underwent single-level fusions were at low risk, patients who underwent fusion of three or four levels had a threefold increased risk of further surgery, compared with single-level fusions (p<.0001), and a predicted 10-year prevalence of 40%.

Lumbar adjacent segment degeneration and disease after arthrodesis and total disc arthroplasty

STUDY DESIGN

Systematic review of published incidence of radiographic adjacent segment degeneration (ASDeg) and symptomatic adjacent segment disease (ASDis) after arthrodesis or total disc replacement.

OBJECTIVE

Assess impact of surgery method and other factors on the incidence of ASDeg and ASDis.

SUMMARY OF BACKGROUND DATA

Twenty-seven articles, none of which were class I or II, met the inclusion criteria. Twenty involved arthrodesis (1732 patients) and 7 involved arthroplasty (758 patients). Nineteen detailed ASDeg and 16 detailed ASDis.

METHODS

Data were established for number of patients, gender, average patient age, incidence of ASDeg and ASDis, average time to follow-up, and level and type of surgery. Multivariate logistic regression was used to identify which parameters had a significant effect on the incidence of ASDeg and ASDis.

RESULTS

Three hundred fourteen of 926 patients in the arthrodesis group (34%) and 31 out of 313 patients in the total disc replacement group (9%) developed ASDeg. (P < 0.0001) Multivariate logistic regression indicated that higher odds of ASDeg were associated with: older patients (P < 0.001); arthodesis (P = 0.0008); and longer follow-up (P = 0.0025). For ASDis, 173/1216 (14%) arthrodesis patients developed ASDis compared to 7/595 (1%) of arthroplasty patients (P < 0.0001). Using multivariate logistic regression, higher odds of ASDis were seen in studies with fusion (P < 0.0001), higher percentages of male patients (P = 0.0019), and shorter follow-up (P < 0.05).

CONCLUSION

Analysis of the literature suggests a correlation between fusion and the development of ASDeg compared to arthroplasty, but this association is dampened by the influence of patient age. There is a stronger correlation between fusion and ASDis compared to arthroplasty. The data supports only a class C recommendation (lowest tier) for the use of arthroplasty to reduce ASDis and disc degeneration compared to arthrodesis.

Surgical versus pharmacologic treatment of intraspinal gout

A controversy between pharmacologic and surgical treatment of intraspinal gout exists in the literature. If gout is diagnosed timely, pharmacologic therapy may avert the need of surgery. The lack of readily available synovial fluid makes the diagnosis particularly difficult. The purpose of this study was to evaluate the clinical pictures and magnetic resonance imaging features in rapid differentiations of intraspinal gout. I retrospectively evaluated lumbar intraspinal tophaceous gout without the classic radiographic punched-out lesions. Four patients (average age, 65 years) had a history of hyperuricemia with multiple tophaceous deposits in the joints or visceral organs or both. The common presentations were low back pain with or without inflammatory reaction (fever, elevated C-reactive protein level, and mild leukocytosis). The patients also presented with intermittent claudication or radiculopathy of variable duration or both. The gouty tophi yielded homogeneous and hypointense masses on T1- and T2-weighted images, with multiple hypointense speckles. The masses were located in bilateral lumbar facet joints in all patients, with additional midline extension along the ligamentum flavum in three. All patients had uneventful outcomes after surgical decompression and pharmacologic treatment. Rapid deposition of tophi may aggravate nerve compression. If neurologic deficits are found, surgical decompression can provide a satisfactory outcome.

LEVEL OF EVIDENCE

Therapeutic study, Level IV. See the Guidelines for Authors for a complete description of levels of evidence.

Salmonella spondylodiscitis in patients without sickle cell disease

The optimal treatment of salmonella spondylodiscitis is controversial. The cases of eight patients who had salmonella spondylitis without sickle cell disease were reviewed. Back pain (100%), fever (75%), and elevated C-reactive protein levels (100%) were common, but gastrointestinal symptoms were not (0%). Six patients had positive blood cultures, and the other two had positive tissue cultures. Group C1 salmonella was the most common serotype. Two patients with coexisting aortic mycotic aneurysms had immediate aneurysm resection. Three others responded favorably to appropriate antibiotics, and three required subsequent surgical reconstruction because of neurologic impairment or osseous instability. Clinical outcomes were significantly better than those of 46 previously reported patients. Salmonella spondylodiscitis usually responds favorably to appropriate antibiotics; consequently, a tissue diagnosis is important. Operative interventions are necessary only for patients with coexisting aneurysms or ongoing osseous instability. A ruptured aortic aneurysm with pseudoaneurysm may mimic a paravertebral abscess, and surgery at the site of an unsuspected aneurysm may precipitate life-threatening hemorrhage. Satisfactory results may be depend on early surgical intervention for a mycotic aneurysm and also are related to host immunity.

Adjacent segment disease after lumbar or lumbosacral fusion: review of the literature

STUDY DESIGN

Review of the literature.

OBJECTIVES

Review the definition, etiology, incidence, and risk factors associated with as well as potential treatment options.

SUMMARY OF BACKGROUND DATA

The development of pathology at the mobile segment next to a lumbar or lumbosacral spinal fusion has been termed adjacent segment disease. Initially reported to occur rarely, it is now considered a potential late complication of spinal fusion that can necessitate further surgical intervention and adversely affect outcomes.

METHODS

MEDLINE literature search.

RESULTS

The most common abnormal finding at the adjacent segment is disc degeneration. Biomechanical changes consisting of increased intradiscal pressure, increased facet loading, and increased mobility occur after fusion and have been implicated in causing adjacent segment disease. Progressive spinal degeneration with age is also thought to be a major contributor. From a radiographic standpoint, reported incidence during average postoperative follow-up observation ranging from 36 to 369 months varies substantially from 5.2 to 100%. Incidence of symptomatic adjacent segment disease is lower, however, ranging from 5.2 to 18.5% during 44.8 to 164 months of follow-up observation. The rate of symptomatic adjacent segment disease is higher in patients with transpedicular instrumentation (12.2-18.5%) compared with patients fused with other forms of instrumentation or with no instrumentation (5.2-5.6%). Potential risk factors include instrumentation, fusion length, sagittal malalignment, facet injury, age, and pre-existing degenerative changes.

CONCLUSION

Biomechanical alterations likely play a primary role in causing adjacent segment disease. Radiographically apparent, asymptomatic adjacent segment disease is common but does not correlate with functional outcomes. Potentially modifiable risk factors for the development of adjacent segment disease include fusion without instrumentation, protecting the facet joint of the adjacent segment during placement of pedicle screws,fusion length, and sagittal balance. Surgical management, when indicated, consists of decompression of neural elements and extension of fusion. Outcomes after surgery, however, are modest.

Combined anterior and posterior surgeries in the treatment of spinal tuberculous spondylitis

Methods for the treatment of tuberculous spondylitis still are controversial. The authors treated 32 consecutive patients with a two-stage surgical technique combined with antituberculous chemotherapy for 1 year. After anterior debridement, fusion with autogenous anterior iliac tricortical strut bone graft was done, and in a second stage, posterior instrumentation and fusion with autogenous posterior iliac corticocancellous bone graft was done 11 days (range, 4-22 days) later. Postoperatively, patients were encouraged to ambulate with brace protection as early as possible. Twenty-nine patients were followed up for a minimum of 2 years (median, 4.7 years; range, 2-10 years) of whom 28 patients achieved solid fusion (97%). All patients had improvement of back pain including the only patient with pseudarthrosis. Neurologic deficits completely recovered in 84% (16 of 19) of patients after 3 months. Kyphotic deformity improved in all 29 patients (34.6 degrees versus 17.3 degrees ) with the average correction angle of 17.3 degrees. Clinically, 27 patients had achieved a satisfactory outcome (93%). There were no evident surgical complications. The authors, therefore, recommend a two-stage surgical technique combined with antituberculous chemotherapy to treat patients with severe vertebral body destruction attributable to tuberculosis because of its high success rate and a low complication rate.