Complications and results of long adult deformity fusions down to l4, l5, and the sacrum.

STUDY DESIGN: This is a consecutive study of patients having undergone surgical treatment of adult lumbar scoliosis. Follow-up ranged from 2 to 13 years (average 5 years). OBJECTIVES: To assess the complications and outcomes of patients with long fusions to L4 (n=23), L5 (n=21), or the sacrum (n=15) and determine if a "deeply seated" L5 segment is protective. SUMMARY OF BACKGROUND DATA: Few studies assess outcomes and complications in adults fused from the thoracic spine to L4, L5, or the sacrum with minimum 2-year follow-up. METHODS: Fifty-eight patients (59 cases; average age 43 years; range 21 to 60) with minimum 2-year follow-up were analyzed for subsequent spinal degeneration and complications. Outcomes were assessed from questionnaires administered at latest follow-up. RESULTS: Sixteen percent of cases (7 of 44) fused short of the sacrum displayed subsequent postoperative distal spinal degeneration, although only three patients were symptomatic. Compared with the group with no subsequent degeneration, this group had a lower improvement in function and pain relief. Other complications for patients fused short of the sacrum included two cases with crosslink breakage, one with neurologic deficit, three with pseudarthroses, one with hook pullout, and one with L5 screw pullout. For cases fused to the sacrum, two cases with deep wound infections and one with loose iliac screw requiring removal were observed. Because two of four cases fused to L5 with subsequent degeneration at L5-S1 were observed to have "deeply seated" L5 segments and two of the four did not, the authors could conclude only that "deep seating" of L5 is not absolute protection. CONCLUSIONS: Fusions short of the sacrum did not have predictable long-term results. Those fused short of the sacrum who developed distal spinal degeneration had worse outcomes. Patients fused to the sacrum did not have a higher complication rate. A "deeply seated" L5 segment does not necessarily protect the L5-S1 disc.

Long-term complications in adult spinal deformity patients having combined surgery a comparison of primary to revision patients.

STUDY DESIGN: This is a comparison of primary (N = 18) to revision (N = 26) combined (anterior and posterior surgery) adult spinal deformity patients with regard to late (>6 months) complications and radiographic/functional outcomes at a minimum 2-year follow-up. OBJECTIVES: To determine whether revision status increases the risk of late complications or offers a poor prognosis for functional outcome in adult deformity patients. SUMMARY OF BACKGROUND DATA: It is known that patients who have combined surgery for adult deformity have a high incidence of perioperative complications. Long-term complications and the effect of revision status have not been clarified in the literature. The functional outcomes for these patients are unclear as to whether or not there is a difference between primary and revision patients. Outside the arena of adult spinal deformity the functional outcomes for revision cases have been disappointing. METHODS: A consecutive series of 44 patients who underwent combined procedures for adult spinal deformity were followed for a minimum of 2 years (average follow-up 42 months). Clinical data were obtained by chart and radiographic review. Major complications were considered to be deep wound infection, pseudarthrosis, transition syndrome, neurologic deficit, and death. Minor complications considered were asymptomatic instrumentation failure (without loss of correction), instrumentation prominence requiring removal, and proximal or distal junctional segmental kyphosis (5-10 degrees ) or subsequent disc space narrowing of 2-5 mm without clinical symptoms. The patients also completed the AAOS Lumbar/Scoliosis MODEMS questionnaires aimed at assessing pain, function, and satisfaction. RESULTS: Minor complications were comparable in both groups: 4 of 18 (22%) in the primary group and 6 of 26 (23%) in the revision group. Major complications were slightly more frequent in the primary group with five complications in 4 patients (4 of 18 patients) (22%) compared with 3 of 26 patients (12%) in the revision group. The incidence of pseudarthrosis was 22% (4 of 18) for the primary group and 4% (1 of 26) for the revision group (P< 0.14). Forty of 44 patients completed the questionnaires. The primary patients functioned at a slightly higher level after surgery than the revision group. The level of pain was also slightly lower at final follow-up in the primary group. Despite these differences, the revision group had a higher level of patient satisfaction. CONCLUSION: At a minimum 2-year follow-up the late complications were not higher in the revision patients than in the primary group. The rate of major long-term complications, specifically pseudarthroses, was higher in the primary group. Patient satisfaction was higher in the revision patients, probably because they were experiencing a greater level of perceived pain and dysfunction at the time of their reconstruction.

Analysis of titanium mesh cages in adults with minimum two-year follow-up.

STUDY DESIGN: This is a study of 66 consecutive adult patients (ages 20-81 years) with sagittal deformities who underwent surgery in which structural titanium mesh cages were implanted into the anterior column during posterior instrumentation and fusion. Follow-up ranged from 24 to 62 months (mean, 33 months). OBJECTIVES: To assess the complications and outcomes of patients with structural cages implanted into the anterior column. SUMMARY OF BACKGROUND DATA: Structural cages for the anterior column are popular in the treatment of adult spinal disorders. Few studies to determine their efficacy have a minimum 2-year follow-up. METHODS: Sixty-six patients with minimum 2-year follow-up were analyzed for cage, spinal fusion, and instrumentation status. Outcomes were assessed by analysis of responses to questionnaires administered to the patients at latest follow-up. RESULTS: No cage failure or extrusion was observed. The average segmental improvement in lordosis with cage implantation was 11 degrees with a loss of correction of less than 1 degrees at latest follow-up. The readability of plain radiographs for assessment of anterior fusions was better than for posterior fusions. The agreement level for judging spines to be fused was two of three for 78% of the anterior levels and 47% of the posterior levels. The remaining posterior fusion levels were unassessable. No statistical difference was found in outcome between the group of patients with suspected nonfused anterior levels and the group with all levels fused. CONCLUSIONS: Structural titanium mesh cages implanted into the anterior column function appropriately to maintain sagittal correction, with rare radiographic complications. Seventy-eight percent of the anterior levels were judged to be fused by observers examining plain radiographs. The outcome at latest follow-up for patients with suspected nonfused anterior levels was similar to that in the group of patients with fusions rated solid at every level.

Intraneural sciatic nerve pressures relative to the position of the hip and knee: a human cadaveric study.

OBJECTIVES: To determine the effects of ipsilateral hip and knee position on intraneural sciatic nerve pressures. DESIGN: Intraneural sciatic nerve pressures measured in intact, fresh cadaveric specimens relative to ipsilateral hip and knee positions. LOCATION: Medical school anatomy laboratory. SUBJECTS: Randomly acquired adult cadavers. INTERVENTION: Pressure transducer placed within the sciatic nerve distal to the femoral attachment of the gluteus maximus. Intraneural pressures measured with the hip placed in 0, 45, and 90 degrees of flexion while the knee was positioned in 90, 45, and 0 degrees of flexion. MAIN OUTCOME MEASUREMENTS: Tissue fluid pressures within the sciatic nerve relative to the position of the ipsilateral hip and knee. Tissue fluid pressure within the sciatic nerve exceeded previously defined critical thresholds for alteration of neural microcirculation and function. Although increased intraneural pressures were realized as the hip was positioned in greater flexion and the knee was extended, clinically relevant pressures were realized only when the hip was flexed to 90 degrees and the knee was fully extended. Pressures with the limbs in these positions were fifty-five millimeters of mercury (range 38 to 74 millimeters of mercury). RESULTS: With the hip held flexed to 90 degrees, statistically significantly increased intraneural pressures were measured as the knee was extended from 90 to 45 degrees of flexion (p = 0.048) and again from 45 to 0 degrees of flexion (p < or = 0.01). With the knee positioned in 45 degrees of flexion, statistically significantly increased intraneural pressures were measured as the hip was flexed from 45 to 90 degrees (p < or = 0.0062). When the knee was held fully extended, statistically significantly increased intraneural pressures were measured as the hip was flexed from 0 to 45 degrees of flexion (p = 0.0006) and again when the hip was brought from 45 to 90 degrees of flexion (p < or = 0.01). CONCLUSIONS: Intraneural sciatic nerve pressures are influenced by the position of the ipsilateral hip and knee. The magnitude of the pressure elevation appears to be related to the excursion of the nerve as the linear distance between the greater sciatic notch and the distal aspect of the leg increases. Intraneural tissue fluid pressures measured within a localized section of the sciatic nerve appeared to exceed published critical thresholds for alterations of blood flow and neural function only when the hip was flexed to 90 degrees and the knee was fully extended.

Complications in the surgical treatment of pediatric high-grade, isthmic dysplastic spondylolisthesis. A comparison of three surgical approaches.

STUDY DESIGN: An analysis of consecutive pediatric patients treated surgically for high-grade spondylolisthesis by one of three surgical procedures with emphasis on complications and functional outcomes. OBJECTIVE: Complications, radiographic results and patient-assessed function, pain, and satisfaction were assessed among three surgical procedures. SUMMARY OF BACKGROUND DATA: The existing literature is in disagreement about whether it is better to fuse without instrumented reduction or to use instrumentation and reduce high-grade dysplastic spondylolisthesis. METHODS: Thirty-two patients had 37 surgical procedures for Meyerding Grade 3 or 4 isthmic dysplastic spondylolisthesis. Eleven patients were treated with an in situ L4-sacrum posterior fusion without decompression (Group 1), 7 had posterior decompression with posterior instrumentation and posterior fusion (Group 2), and 19 patients had reduction and a circumferential fusion procedure (Group 3). All patients had new radiographs taken at time of follow-up (average, 3.1 years; range, 2 years-10 years, 1 month) and completed a functional outcome questionnaire. RESULTS: The incidence of pseudarthrosis was 45% (5 of 11) in Group 1, 29% (2 of 7) in Group 2, and 0% (0 of 19) in Group 3. All seven who had pseudarthrosis had small L5 transverse process surface area (< 2 cm2; P = 0.004). Only one patient had a neurologic deficit (unilateral extensor hallucis longus weakness) at time of follow-up. There were no significant differences among the groups in function, pain, and satisfaction in patients in whom solid fusion was obtained, but the scores were highest in Group 3. CONCLUSIONS: In situ fusion surgery in patients with high-grade spondylolisthesis with small L5 transverse processes (surface area, < 2 cm2) results in a high rate of pseudarthrosis. Circumferential procedures result in the highest rate of fusion and are effective in achieving fusion in those patients with established pseudarthrosis. The use of long (> 60 mm) iliac screws bilaterally (n = 21) in addition to bicortical sacral screws (four-point sacral-pelvis fixation) along with anterior column fusion reduces the risk of instrumentation failure in a decompression and reduction procedure. Outcomes of function, pain, and satisfaction are excellent in those in whom fusion is achieved. The risks in circumferential fusion-reduction procedures are acceptable.

MRI-radiofrequency tissue tagging in patients with aortic insufficiency before and after operation.

BACKGROUND: Magnetic resonance imaging tissue tagging is a relatively recent methodology that describes ventricular systolic function in terms of intramyocardial ventricular deformation. Because the analysis involves the use of many intramyocardial points to describe systolic deformation, it is theoretically more sensitive at describing subtle differences in regional myocardial fiber shortening when compared with conventional measures of ventricular function such as wall thickening. The objectives of this study were (1) to define sensitive indices of ventricular systolic deformation to assist the clinician in the surgical evaluation of patients with aortic insufficiency, and (2) to quantify differences in regional systolic deformation before and after surgery for aortic insufficiency. METHODS: Magnetic resonance imaging with tissue tagging was performed on 10 normal volunteers and 8 patients with chronic severe aortic insufficiency. Follow-up postoperative studies (5.4+/-1.1 months) were obtained in 6 patients who underwent Ross procedure (1 patient), David procedure (1), and St. Jude aortic valve replacement (4). RESULTS: There was no significant difference in fractional area change, overall circumferential shortening, or overall radial thickening among the normal group, the preoperative aortic insufficiency group, or the postoperative aortic insufficiency group. However, on a regional basis, there was a decrease in posterior wall circumferential strains in the postoperative aortic insufficiency group (29%+/-13% preoperative aortic insufficiency (n=6) versus 24%+/-12% postoperative aortic insufficiency (n=6), p=0.02). CONCLUSIONS: On regional analysis, there was a small but significant decrease in posterior wall circumferential shortening after operation. Magnetic resonance imaging tissue tagging is a sensitive and clinically applicable method of quantifying regional ventricular wall function before and after intervention for aortic insufficiency.

Magnetic resonance imaging provides evidence for remodeling of the right ventricle after single-lung transplantation for pulmonary hypertension.

BACKGROUND: In end-stage pulmonary hypertension (PH), the degree of right ventricular (RV) dysfunction has been considered so severe as to require combined heart-lung transplantation. Nevertheless, left ventricular (LV) and RV hemodynamics return to relatively normal levels after single-lung transplantation (SLT) alone. Accordingly, to test the hypothesis that LV and RV systolic function improves after SLT and that the dilated, thick-walled RV reverts to more normal geometry, we used cine MRI and finite-element (FE) analysis to study patients with end-stage PH. METHODS AND RESULTS: Seven patients with end-stage PH underwent cine MRI before and after SLT, and eight normal volunteers were also imaged with cine MRI. Short-axis images at the midventricular level were analyzed with customized image-processing software. The LV and RV ejection fractions, velocity of fiber shortening, RV end-diastolic (ED) and end-systolic (ES) chamber areas, and RV ES and ED wall thicknesses were calculated directly from the MRI images. Two-dimensional FE models of the heart were constructed from the MRI images at early diastole. LV and RV pressures were measured in the patients with a cardiac catheterization before and after SLT. Models were solved to yield diastolic LV, RV, and septal wall stresses. By use of a nonlinear optimization algorithm, LV and RV diastolic maternal properties were determined by minimization of the leastsquares difference between FE model-predicted and MRI-measured LV, RV, and epicardial chamber areas and circumferences. The results demonstrated a substantial reduction in RV wall stress after SLT (1.8 x 10(5) dynes/cm2 pre-SLT to 2 x 10(4) dynes/cm2 post-SLT; P < .001). The average RV diastolic elastic modulus was reduced significantly after SLT (1.5 x 10(6) dynes/cm2 pre-SLT to 1 x 10(5) dynes/cm2 post-SLT; P = .01), but there was no change in the LV elastic modulus. RV velocity of fractional shortening increased significantly after SLT (0.23 pre-SLT to 0.58 post-SLT, P = .02), and RV ED and ES wall thicknesses were reduced significantly (ED, 0.86 cm pre-SLT to 0.65 cm post-SLT, P = .03 and ES, 1.06 cm pre-SLT to 0.72 cm post-SLT, P = .005). CONCLUSIONS: These results provide evidence supporting the contention that LV and RV systolic function improved after SLT for end-stage PH and that the RV underwent significant remodeling within 3 to 6 months after lung transplantation.