Complications and predictive factors for the successful treatment of flatback deformity (fixed sagittal imbalance).

STUDY DESIGN: This is an analysis of consecutive cases of flatback deformity (fixed sagittal imbalance), treated by one of two surgeons at a university hospital. OBJECTIVE: To define factors that contribute to results with treatment of flatback syndrome, classify types of sagittal deformities, and discuss complications. SUMMARY OF BACKGROUND DATA: There are few reports that detail the results and complications of current instrumentation and osteotomy techniques for correction of fixed sagittal deformities. METHODS: Twenty-eight patients treated with osteotomies for sagittal imbalance were eligible for 2-year minimum follow-up (average, 3.6 years). Patients were classified (segmental imbalance, Type 1; or global imbalance, Type 2) and evaluated by upright radiographs, chart review, and a questionnaire. RESULTS: Twenty-eight (100%) patients returned the questionnaire, and 28 had current radiographs. Five treatment groups were evaluated based on osteotomy type (anterior, posterior [Smith-Petersen], both, or pedicle subtraction) and use of anterior structural grafting. All patients were treated with modern bilateral hook-rod-screw constructs. Mean correction at the osteotomy levels was 25 degrees for Type 1 deformities and 30 degrees for Type 2 (P < 0.05). Sagittal correction averaged 6.6 cm in Type 2 deformities (P < 0.05). Questionnaire analysis showed a significant and persistent reduction in subjective pain level. There were seven patients with 11 total complications and no neurologic deficits. Associations among patients who were not satisfied with their results (n = 4) included insufficient sagittal correction (P = 0.045), pseudarthrosis (P = 0.045), coronal imbalance, and four or more medical comorbidities (P = 0.03). CONCLUSIONS: Satisfaction with the results of treatment may be reduced in patients with four or more major co-existent medical problems, insufficient sagittal correction, and resultant pseudarthrosis.

Minimum 5-year results of degenerative spondylolisthesis treated with decompression and instrumented posterior fusion.

STUDY DESIGN: An analysis of consecutive cases of degenerative spondylolisthesis treated by one of two surgeons at a university hospital. OBJECTIVES: To assess at a minimum 5-year follow-up the complication rate, reoperation rate, radiographic results, and patient satisfaction with surgical treatment of lumbar degenerative spondylolisthesis by means of segmental posterior instrumented fusion with decompression. SUMMARY OF BACKGROUND DATA: No reports of minimum 5-year follow-up for surgical treatment of degenerative spondylolisthesis were found in the literature. METHODS: The potential study population consisted of 49 consecutive patients who had undergone no prior surgery for degenerative spondylolisthesis (average age, 66.7 years; range, 52.2-78.7 years) with mean follow-up of 6.5 years (range, 5-10.75 years) who were treated with decompression, autogenous iliac crest bone grafting, intertransverse process fusion, and segmental (pedicle screw) instrumentation. Eight patients had died; the remaining 41 were included in the study sample. Thirty-six (88%) of the 41 patients returned an outcome questionnaire and had current radiographs. RESULTS: There was one case of instrument failure (one broken screw with late fusion), and one superficial infection. There were no neurologic deficits, no pseudarthroses, no recurrent stenosis at the fused segment, and no progression of deformity at the fused level. Five patients had symptomatic adjacent level transition syndromes. There were seven additional currently asymptomatic radiographic transition syndromes. Segmental sagittal Cobb angles were maintained at the fused level (17.7 +/- 8-18.8 +/- 7 degrees). Eighty-three percent reported satisfaction with the procedure, 86% thought their back and leg pain was still significantly better than before surgery, and 77% would have the procedure again if needed. Poor satisfaction (n = 4) was associated with more than four medical comorbidities (P < 0.03). A significant number (12 of 49, 24%) of patients had died or were ill more than 5 years after surgery. CONCLUSIONS: Radiographic transition syndromes were common. Major complications (2%), implant failures (2%), and symptomatic pseudarthroses (0%) were low.

Femoral neck fracture fixation: a biomechanical study of two cannulated screw placement techniques.

This biomechanical study evaluated two different methods of femoral neck fracture fixation. Ten pairs of embalmed femora were used. A standardized midcervical osteotomy was performed. One side from each pair was fixed with either conventional (central) or calcar (cortical adjacent) screw placement. The femora pairs then were subjected to cyclic and load to failure biomechanical testing. The results demonstrated significant improved stability, load, stiffness, and displacement in all tested parameters for the group with calcar screw fixation. Grossly, the conventional fixation group tended to fail in an excessively varus position, while the calcar fixation group failed with impaction of the head on the calcar, a potentially stable position.

Effect of lindane on hormonal control of reproductive function in the female rat.

The effect of the gamma isomer of 1,2,3,4,5,6-hexachlorocyclohexane, lindane, on reproductive function in the female rat was examined in two experiments. In the first experiment, chronic treatment with 0, 5, 10, 20, and 40 mg/kg lindane delayed vaginal opening and disrupted ovarian cyclicity until approximately 110 days of age. Thereafter, regular ovarian cycles were present in the majority of females in all dose groups. When killed on the day of vaginal proestrus, the females receiving the two higher doses of lindane had smaller pituitary and uterine weights, lower serum and pituitary luteinizing hormone (LH) and prolactin, and higher pituitary follicle stimulating hormone (FSH) concentrations than the oil-treated control females. Serum estrogen concentrations were not different from controls in the 5 and 20 mg/kg groups, significantly greater than the controls in the 10 mg/kg group, and significantly less than the controls in the group receiving 40 mg/kg. In a second experiment, the uterine weight and pituitary hormone response of 28-day-old, lindane-treated females to a 10-micrograms injection of estradiol benzoate (EB) were investigated. The uteri of the lindane-treated prepubertal females were smaller than controls at 30 hr after EB injection. Furthermore, the EB-induced increase in serum luteinizing hormone, observed at 30 hr after EB injection, was lower in the lindane-treated animals. Similarly, the reduction in pituitary LH, FSH, and prolactin induced by EB was not as great in the lindane-treated animals as in the controls. Serum estrogen concentrations in the lindane-treated animals were not different from controls. These data indicate that lindane may effectively block the response of estrogen-dependent tissues to this ovarian steroid hormone and that this apparent antiestrogenic effect of lindane is responsible for the disturbances observed in the neuroendocrine control of ovarian function in the rat.

Age-related changes in the regional distribution of hormones in the male rat anterior pituitary.

Some heterogeneity in the localization of hormone-containing cells has been reported in the mammalian anterior pituitary. Since age-related changes are present in pituitary hormone concentrations, the present study was designed to explore if such changes in the male rat are regionally consistent. The results show clear geographic patterns in the presence of immunoreactive LH, FSH, prolactin and TSH. In the two year-old male, specific regional declines in hormone concentrations were present. With one regional exception, such was not the case when values were expressed in total hormonal content. A fall in gonadotropins still appeared in the medial area of the most caudal strip. The results suggest that with age, there is a displacement of hormone-containing cells in the pituitary and that for the gonadotropes this effect appears to be more prominent within the medio-caudal area.

Regional patterning of hormones in the female rat anterior pituitary: disproportionate changes over the estrous cycle.

The present study addressed the possibility that regional differences exist in the typical patterning of anterior pituitary hormones seen over the estrous cycle. The results show that LH in the rostral area of the pituitary, significantly higher than in other regions on diestrus, rises markedly on proestrus before falling late on that afternoon to concentrations comparable to other areas. Smaller cyclic changes were seen for lateral and caudo-central areas. The pattern of regional FSH concentrations on diestrus, while similar to LH, does not show the proestrus fall in the rostral region. Prolactin declines from a high on diestrus I to a low on late proestrus, but no regional disparities are present. TSH shows distinct regional differences and a fall in concentrations that coincides with the reported rise in serum estradiol. These findings indicate that the preovulatory surge of LH may represent a regionally disproportionate event, possibly involving inequalities in the relative amounts of gonadotropin-releasing hormone reaching various areas of the pituitary or differences in the ability of this releasing hormone to trigger LH release.