Analysis of the direct cost of surgery for four diagnostic categories of adult spinal deformity

BACKGROUND CONTEXT

Existing literature on adult spinal deformity (ASD) offers little guidance regarding an evidence-based approach to care. To optimize the value of medical treatment, a thorough understanding of the cost of surgical treatment for ASD is required.

PURPOSE

To evaluate four clinically and radiographically distinct groups of ASD and identify and compare the cost of surgical treatment among the groups.

STUDY DESIGN/SETTING

Multicenter retrospective study of consecutive surgeries for ASD.

PATIENT SAMPLE

Three hundred twenty-five consecutive ASD patients treated between 2008 and 2010.

OUTCOME MEASURES

Cost data were collected from hospital administrative records on the direct costs (DCs) incurred for the episode of surgical care, excluding overhead.

METHODS

Based on preoperative radiographs and history, patients were categorized into one of four diagnostic categories of deformity: primary idiopathic scoliosis (PIS), primary degenerative scoliosis (PDS), primary sagittal plane deformity (PSPD), and revision (R). Analysis of variance and generalized linear model regressions were used to analyze the DCs of surgery and to assess differences in costs across the four diagnostic categories considered.

RESULTS

Significant differences were observed in DC of surgery for different categories of ASD, with surgical treatment for PDS the most expensive followed in decreasing order by PSPD, PIS, and R (p<.01). Results further revealed a significant positive relationship between age and DC (p<.01) and a significant positive relationship between length of stay and DC (p<.01). Among PIS patients, for every incremental increase in levels fused, the expected DC increased by $3,997 (p=.00). Fusion to pelvis also significantly increased the DC of surgery for patients aged 18 to 29 years (p<.01) and 30 to 59 years (p<.01) but not for 60 years or more (p=.86).

CONCLUSIONS

There is an increasing DC of surgery with increasing age, length of hospital stay, length of fusion, and fusions to the pelvis. Revision surgery is the least expensive surgery on average and should therefore not preclude its consideration from a pure cost perspective.

A posterolateral microsurgical approach to extreme-lateral lumbar disc herniation

Extreme-lateral lumbar disc herniations present a surgical challenge because the conventional posterior approach requires bone resection for complete visualization of the pathology. The authors have identified constant anatomical landmarks in cadaveric dissections that facilitate access to the intervertebral foramen when combined with a posterolateral approach, as described by Watkins, for lumbar spinal fusion. The authors describe a technique that allows rapid localization and safe excision of these extreme-lateral lumbar disc herniations without the need for bone resection.

Thoracic and thoracolumbar kyphosis in adults

STUDY DESIGN

Author experience and literature review.

OBJECTIVES

To investigate the spectrum of adult kyphosis and to discuss the various surgical and nonsurgical treatment options.

SUMMARY OF BACKGROUND DATA

Kyphosis with its various etiologies and associated pathophysiologies has been discussed in the literature for many decades. The nonsurgical treatment primarily consists of symptom reduction via physical therapy and has not changed significantly for decades. The surgical treatment, however, has changed dramatically. A decade ago, most large kyphotic deformities required anterior and posterior procedures. With the advent of numerous posterior osteotomy techniques and pedicle fixation, most of these deformities are now treated via posterior methods only.

METHODS

Using literature review and the author's experience, kyphosis and its characteristics will be discussed. Important details pertinent to presurgical planning and execution of surgical will be discussed. Three cases will be presented to illustrate the surgical treatment options for three qualitatively different kyphotic deformities.

RESULTS

Flexible kyphotic deformities may respond well to aggressive facetectomies and cantilever corrections. Multisegmental osteotomies may be most appropriate for long sweeping deformities. Fixed, sharply, angulated deformities may respond best to pedicle subtraction osteotomies or vertebral column resections.

CONCLUSION

Segmental pedicle screw fixation coupled with one of four posterior osteotomy/resection techniques can be used to address most sagittal plain deformities. Careful application of these techniques is important. Smith-Petersen and Ponte osteotomies are most appropriate for long sweeping deformities with mobile anterior columns. Pedicle subtraction osteotomies and vertebral column resections are most appropriate for fixed, sharply angulated spinal deformities. The successful application of these techniques is dependent on accurate preoperative evaluation of the structural properties of the kyphosis and meticulous execution of the surgical technique.

Donor-specific immune response after aortic valve allografting in the rat

The allospecific immune response in rats to a major histocompatibility complex-disparate aortic valve allograft was investigated using three in vitro assays. In each assay, DA strain (RT-1a) rats served as allograft recipient and syngeneic donor, Lewis strain (RT-1l) rats were allogeneic donors, and Buffalo (RT-1b) rats provided third-party control cells. Mixed lymphocyte cultures using spleen cells demonstrated donor-specific stimulation indices of 3.04 +/- 0.44, 4.14 +/- 0.62, and 6.32 +/- 0.60 at 7, 14, and 28 days, respectively, after aortic valve allografting; 8.19 +/- 2.91, 8.51 +/- 1.25, and 10.80 +/- 0.53 after skin allografting; and 1.84 +/- 0.56, 1.82 +/- 0.38, and 1.82 +/- 0.53 after aortic valve isografting. Limiting dilution analysis of splenocytes showed a donor-specific cytotoxic T lymphocyte precursor frequency at 7, 14, and 28 days of 1:6,853, 1:4,714, and 1:1,964 after aortic valve allografting; 1:4,181, 1:1,611, and 1:1,018 after skin allografting; and 1:14,517, 1:11,882, and 1:10,995 after aortic valve isografting. Flow cytometry detected an increase in the level of donor-specific anti-T cell antibodies in both valve and skin allograft recipients but not in isografted animals. Aortic valve allografting from Lewis into DA rats elicits allospecific cellular and humoral immune responses similar in magnitude to skin allografting but somewhat slower in onset. Investigation of the immune response to aortic allografts in humans is warranted, as donor-specific T cells, antibodies, or both may damage the allograft.

The Cryolife-O'Brien composite aortic stentless xenograft: surgical technique of implantation

The Cryolife-O'Brien (Cryolife International, Atlanta, GA; formerly the Bravo Cardiovascular Inc valve) stentless porcine aortic xenograft (model 300) is a composite valve of three noncoronary leaflets, symmetric in configuration with a broad coaptive leaflet surface. Because the valve has only a superior aortic wall cuff, a single continuous suture line of 3/0 Prolene provides a rapid, safe implantation. The ideal recipients are elderly patients, who benefit from a short cardiopulmonary bypass period and whose degenerative calcific valves are generally symmetric. The step-by-step technique of implantation is outlined, as are the principles of maintaining symmetry during implantation. The stentless valve has been used for aortic valve replacement in 55 elderly patients, with no deaths and minimal morbidity.

Allograft heart valve viability and valve-processing variables

BACKGROUND

The impact of allograft valve viability on valve durability remains controversial. Analyses of our clinical results have demonstrated the superiority of the cryopreserved valve viable at the time of implantation over the 4 degrees C stored valve nonviable at the time of implantation. In this study, we quantitatively assessed the effects on viability of current and past valve-processing protocols at The Prince Charles Hospital.

METHODS

The viability of pulmonary valves was quantitatively analyzed by thin-layer autoradiography to assess the effects of donor type, antibiotics, and valve storage.

RESULTS

Control valve segments obtained from beating-heart donor valves had a higher initial viability (0.92+/-0.02) than nonbeating-heart donor valves (0.66+/-0.03). Cryopreservation after low-dose antibiotic sterilization significantly reduced viability to 50% to 60% of the control, and in the presence of amphotericin B, viability dropped further to 10% to 36% of the control. After 7 days' storage at 4 degrees C, viability was reduced to 2% of control and to 0% viability after 21 days.

CONCLUSIONS

For maximal preimplantation viability, valves should be procured as soon as possible after cessation of heart beat and should be cryopreserved if they are not to be clinically implanted within 1 to 2 days. Amphotericin B should not be used in conjunction with cryopreservation if viability is to be maximized.

Haemodynamics and left ventricular mass regression: a comparison of the stentless, stented and mechanical aortic valve replacement

OBJECTIVE

Our objective was to compare the degree of change in hemodynamics and left ventricular mass (LVM) regression after aortic valve replacement (AVR) with stentless, stented and mechanical valves.

METHODS

Patients greater than 59 years of age had AVR for aortic stenosis with the stentless xenograft (Cryolife-O'Brien, CLOB), stented xenograft (Carpentier-Edwards, C-E) or mechanical valve (ATS). One-hundred and forty-two patients received stentless, 40 stented, and 69 mechanical valves (mean age 74 +/- 6 vs. 72 +/- 7 and 67 +/- 6 years, respectively). Serial echocardiography was performed.

RESULTS

The left ventricular outflow tract diameter was similar pre-operatively in the stentless versus the stented versus the mechanical groups (2.2 +/- 0.4 vs. 2.3 +/- 0.2 vs. 2.2 +/- 0.3 cm; P, n.s). The effective orifice area was larger immediately post-operatively in the stentless versus the stented or the mechanical group (2.4 +/- 0.4 vs. 2.0 +/- 0.6 vs. 2.0 +/- 0.7 cm2, P = 0.0001 for both comparisons). The peak aortic gradient at 6 months was significantly less in the stentless versus the stented and mechanical groups (15 +/- 7 vs. 25 +/- 9 vs. 22 +/- 9 mmHg, P < 0.0001). LVM regressed over 6 months in all subgroups: stentless 272 +/- 64 g vs. 220 +/- 72 g, P = 0.0001, stented 257 +/- 58 vs. 230 +/- 74 g, P = 0.02, and mechanical 267 +/- 95 vs. 204 +/- 54 g, P = 0.003. The reduction in LVM was greater in the stentless versus the stented (P = 0.05) but similar to the mechanical group.

CONCLUSIONS

AVR with the stentless xenograft results in superior hemodynamics compared to the stented and mechanical valve replacements. AVR in all three groups leads to a significant regression of left ventricular hypertrophy within 6 months. However the reduction in LVM is greater in subjects with stentless and mechanical valves, which may have prognostic significance.

Establishment of a viable homograft cardiac valve bank: a rapid method of determining homograft viability

A method for determining the viability of homograft valves has been developed based on sequential measurements of glucose and pH levels of the culture medium in which cardiac valves have been maintained for short periods at 37 degrees C. Viable valves, as determined by tissue culture, showed a characteristic pattern of glucose utilization and pH reduction that was absent in nonviable valves. Upon explantation of valve leaflet fragments into tissue culture, only fragments from valves that metabolized glucose produced viable fibroblast cultures. The method reported here is rapid, requires no specialized equipment, is nondestructive, and can directly determine the viability of the valve homograft within 24 to 48 hours.

Long-term results of the viable cryopreserved allograft aortic valve: continuing evidence for superior valve durability

From December 1969 to May 1975, 124 patients underwent aortic valve replacement with an allograft aortic valve sterilized by incubation in a low dose antibiotic solution and stored by refrigeration at 4 degrees C (4 degrees C stored valve group). From June 1975 to December 1987, 231 patients received an allograft aortic valve, sterilized by the same low dose antibiotic solution, but stored by cryopreservation in liquid nitrogen at -196 degrees C (cryopreserved valve group). The 4 degrees C stored valves were essentially nonviable, whereas the cryopreserved valves were viable at implantation. Of the 355 aortic valve replacements, associated procedures were performed in 127 patients. The 30-day mortality was 8.9% (confidence limits [C.L.] 6.2% ... 12.3%) (4 degrees C stored) and 4.8% (C.L. 3.3% ... 6.7%) (cryopreserved). Actuarial survival was similar in both groups, being 71% and 67% at 10 years in the 4 degrees C stored and cryopreserved valve groups, respectively (P = .18). The probability of a thromboembolic event was low, but appeared higher in the 4 degrees C stored valve group (actuarial freedom at 10 years, 90%) than the cryopreserved valve group (actuarial freedom at 10 years, 98%) (P = .01) probably related to associated mitral valve surgery. The actuarial freedom from allograft valve endocarditis at 10 years was 94% and 95% for the 4 degrees C stored and cryopreserved valve groups, respectively (P = .23). Reoperation was undertaken in 34 patients in the 4 degrees C stored group and 12 patients in the cryopreserved valve group for leaflet degeneration, endocarditis, or technical reasons.(ABSTRACT TRUNCATED AT 250 WORDS)

Preoperative platelet dysfunction increases the benefit of aprotinin in cardiopulmonary bypass

BACKGROUND

This study was designed to determine the benefit of aprotinin therapy in reducing bleeding during and after cardiopulmonary bypass in patients with preoperative platelet dysfunction. Platelet function involvement in the mechanism by which aprotinin acts was also investigated.

METHODS

In a double-blind, randomized study, patients received high-dose aprotinin (n = 54) or placebo (n = 52). Whole blood aggregation was measured preoperatively. Platelet function and activation in both groups were assessed intraoperatively and postoperatively at five times.

RESULTS

Aprotinin significantly reduced perioperative bleeding and postoperative blood transfusion. Placebo-treated patients with reduced preoperative platelet aggregation bled more postoperatively, but aprotinin reduced the bleeding in patients with normal or reduced platelet function to similar levels. Any cardiopulmonary bypass-induced changes in platelet aggregation, platelet activation as measured by P-selectin expression, and von Willebrand factor antigen and function were similar in aprotinin-treated and placebo-treated groups.

CONCLUSIONS

The mechanism by which aprotinin reduced bleeding was independent of any effect on platelet function. However, aprotinin produced a greater reduction in bleeding among patients whose condition was hemostatically compromised by preoperative platelet dysfunction.

Preoperative spinal canal investigation in adolescent idiopathic scoliosis curves > or = 70 degrees

STUDY DESIGN

This is a prospective evaluation of a consecutive series of patients with adolescent idiopathic scoliosis (AIS) with curves > or = 70 degrees.

OBJECTIVE

The authors investigated the possibility that large curve size may constitute an atypical presentation of idiopathic scoliosis suggestive of underlying neurologic pathology, which would warrant preoperative investigation.

SUMMARY OF BACKGROUND DATA

The potential for intraspinal pathology to cause scoliosis is well accepted. The incidence of spinal canal abnormalities in congenital or atypical scoliosis may be as high as 30-60%. Identification of clinical neurologic deficits, congenital abnormalities, or atypical features of scoliosis are often helpful in identifying the subpopulation of scoliosis patients at risk for spinal canal pathology.

METHODS

Thirty-three consecutive patients with large (> or = 70 degrees) adolescent idiopathic scoliosis (AIS) and without evidence of neurologic or congenital abnormalities, were evaluated with either computed tomography/myelogram (n = 3) or magnetic resonance imaging (n = 30) to assess the entire spinal canal.

RESULTS

None of the studies revealed any pathology of the neuraxis, and all 33 patients were treated with surgery without any neurologic sequelae.

CONCLUSIONS

Preoperative investigation of the central neuraxis is not mandatory in large (> or = 70 degrees) but otherwise typical AIS curves. These large curves do not appear to suggest associated spinal canal anomalies.

Anterior single rod instrumentation for thoracolumbar adolescent idiopathic scoliosis with and without the use of structural interbody support

STUDY DESIGN

A radiographic and clinical outcomes analysis of 41 patients treated for thoracolumbar adolescent idiopathic scoliosis utilizing a single anterior rigid rod construct.

OBJECTIVES

To evaluate the necessity of structural interbody support to improve primary curve correction and preserve or augment lordosis when used in conjunction with a single anterior rigid rod construct, to identify parameters that predict horizontalization of the lowest instrumented vertebra, adjacent disc angulation, and distal uninstrumented vertebrae, and to assess patient satisfaction following surgery.

BACKGROUND DATA

Instrumentation-induced kyphosis has been a concern with nonrigid anterior systems used in the past for the treatment of scoliosis. Interbody structural support has been recommended to maintain appropriate sagittal profile when anterior systems are utilized. It has also been suggested that the use of structural interbody support creates a fulcrum to increase curve correction when compression is applied to the convexity of the deformity. However, the necessity of interbody structural support when used in conjunction with a rigid anterior system has not been previously evaluated in patients with adolescent idiopathic scoliosis.

MATERIALS AND METHODS

Forty-one patients mean age 15.9 years (range 12.1-18.6 years) with thoracolumbar adolescent idiopathic scoliosis underwent anterior spinal fusion using a single 6.0 to 6.5 mm solid rod construct between June 1995 and August 1999 performed by the senior author (T.G.L.). Four additional patients with thoracolumbar curves with similar anterior instrumentation over the same time period were lost to follow-up or had incomplete records and were not included in the study. Structural interbody support was used in 21 patients and packed morselized autograft alone was used in 20 patients. The patients in the group with packed morselized bone alone generally underwent surgery earlier in the series before the author began using structural interbody support on a regular basis. Each patient had a minimum follow-up of 3 years. Preoperative, initial, and most recent (>3 years) follow-up radiographs were reviewed to determine in each group Cobb angle measurements, flexibility of primary, secondary, and fractional curves, apical and end vertebral translation, lowest instrumented vertebral and caudal disc angulation, global coronal and sagittal balance, and sagittal Cobb measurements in both instrumented levels as well as lumbar lordosis (T12-S1). In addition, the SRS outcomes instrument was completed by 38 of 41 patients.

RESULTS

The mean preoperative primary curve in patients with structural support was 47 degrees (Group II) and 45 degrees in patients without structural support (Group I). Mean curve correction was to 13 degrees in Groups I and II. One patient in Group II became slightly more unbalanced at final follow-up; otherwise all were improved after surgery. Sagittal measurements over instrumented segments as well as total lumbar lordosis (T12-S1) was maintained between preoperative and final postoperative values in both groups. Similarly, in both groups, when horizontalization of the distal end instrumented vertebra was achieved on the preoperative reverse side-bending radiograph, more normal relationships were achieved between instrumented and distal noninstrumented segments (adjacent disc angulation and fractional lumbar curve) at final follow-up (P <or= 0.01). Patients in both groups were equally pleased with their clinical outcomes based on the SRS outcomes instrument.

CONCLUSIONS

The use of interbody structural support does not appear to be necessary to maintain an appropriate sagittal profile or to maximize coronal curve correction when a rigid rod construct with packed morselized bone is used for the treatment of thoracolumbar adolescent idiopathic scoliosis. Parameters predicting horizontalization of the lower instrumented vertebra and uninstrumented segments below the construct were identified, which, if achieved, should predict an optimal long-term outcome. Clinical outcomes were very good in both groups.

Intracanalicular osteochondroma producing spinal cord compression in hereditary multiple exostoses

Spinal cord compression is an unusual but potentially catastrophic manifestation of hereditary multiple exostoses (HMEs). Isolated, osteochondromas are usually of little significance. However, if they are located near neurologic structures, they may cause irritation due to mechanical compression. In patients with HMEs who present with neck or back pain, and particularly in those who have neurologic symptoms in the upper or lower extremities, a diagnosis of intracanalicular osteochondroma should be presumed until proven otherwise. Prompt diagnosis and surgical excision affords the best prognosis for these patients who have spinal cord compression secondary to intracanalicular osteochondroma.

A study of the cells in the explanted viable cryopreserved allograft valve

From June 1975 to December 1987, 231 patients underwent aortic valve replacement with a viable cryopreserved allograft aortic valve. Throughout this era, a uniform procurement and preservation was used to maintain leaflet fibroblast viability. The allograft valve was obtained from coroner's autopsies within 24 hours of death, and more recently from organ donors, incubated for 24 hours in low dose antibiotic solution followed immediately by cryopreservation (mean time interval 39 hours after donor death). Viability was ensured by monitoring glucose utilization of the aortic and pulmonary valves and by demonstrating fibroblast growth in tissue cultured from the pulmonary valve. A uniform protocol for valve preparation was used during the entire experience. Nine allograft aortic valves have been obtained by eight reoperations (two were for leaflet degeneration) and one autopsy. The time intervals from implantation to explantation were 2 months, 10 months, 20 months, 22 months, 2.2 years, 5 years, 8.3 years, 9.2 years, and 10.8 years. Histologic examination of the leaflet tissue disclosed a variable degree of cellularity, ranging from a highly cellular matrix (9.2 years) to minimal cellularity (20 months). Within the same valve (10 months), one leaflet was completely acellular with a moderate degree of cellularity in the other two leaflets. The competent valve recovered at autopsy (8.2 years) was essentially acellular. Fibroblasts could consistently be cultured from leaflets in which viable cells were seen histologically. Chromosomal analysis of cultured cells from a valve leaflet (9.2 years) that was implanted with a donor and recipient sex mismatch demonstrated persistence of donor cells.(ABSTRACT TRUNCATED AT 250 WORDS)

How to do safe sternal reentry and the risk factors of redo cardiac surgery: a 21-year review with zero major cardiac injury

OBJECTIVES

Resternotomy is a common part of cardiac surgical practice. Associated with resternotomy are the risks of cardiac injury and catastrophic hemorrhage and the subsequent elevated morbidity and mortality in the operating room or during the postoperative period. The technique of direct vision resternotomy is safe and has fewer, if any, serious cardiac injuries. The technique, the reduced need for groin cannulation and the overall low operative mortality and morbidity are the focus of this restrospective analysis.

METHODS

The records of 495 patients undergoing 546 resternotomies over a 21-year period to January 2000 were reviewed. All consecutive reoperations by the one surgeon comprised patients over the age of 20 at first resternotomy: M:F 343:203, mean age 57 years (range 20 to 85, median age 60). The mean NYHA grade was 2.3 [with 67 patients (I), 273 (II), 159 (III), 43 (IV), and 4 (V classification)] with elective reoperation in 94.6%. Cardiac injury was graded into five groups and the incidence and reasons for groin cannulation estimated. The morbidity and mortality as a result of the reoperation and resternotomy were assessed.

RESULTS

The hospital/30 day mortality was 2.9% (95% CI: 1.6%-4.4%) (16 deaths) over the 21 years. First (481), second (53), and third (12) resternotomies produced 307 uncomplicated technical reopenings, 203 slower but uncomplicated procedures, 9 minor superficial cardiac lacerations, and no moderate or severe cardiac injuries. Direct vision resternotomy is crystalized into the principle that only adhesions that are visualized from below are divided and only sternal bone that is freed of adhesions is sewn. Groin exposure was never performed prophylactically for resternotomy. Fourteen patients (2.6%) had such cannulation for aortic dissection/aneurysm (9 patients), excessive sternal adherence of cardiac structures (3 patients), presurgery cardiac arrest (1 patient), and high aortic cannulation desired and not possible (1 patient). The average postop blood loss was 594 mL (95% CI:558-631) in the first 12 hours. The need to return to the operating room for control of excessive bleeding was 2% (11 patients). Blood transfusion was given in 65% of the resternotomy procedures over the 21 years (mean 854 mL: 95% CI 765-945 mL) and 41% over the last 5 years.

CONCLUSIONS

The technique of direct vision resternotomy has been associated with zero moderate or major cardiac injury/catastrophic hemorrhage at reoperation. Few patients have required groin cannulation. In the postoperative period, there was acceptable blood loss, transfusion rates, reduced morbidity, and moderate low mortality for this potentially high risk group.

Adaptation of the animal welfare assessment grid (AWAG) for monitoring animal welfare in zoological collections

Animal welfare monitoring is an essential part of zoo management and a legal requirement in many countries. Historically, a variety of welfare audits have been proposed to assist zoo managers. Unfortunately, there are a number of issues with these assessments, including lack of species information, validated tests and the overall complexity of these audits which make them difficult to implement in practice. The animal welfare assessment grid (AWAG) has previously been proposed as an animal welfare monitoring tool for animals used in research programmes. This computer-based system was successfully adapted for use in a zoo setting with two taxonomic groups: primates and birds. This tool is simple to use and provides continuous monitoring based on cumulative lifetime assessment. It is suggested as an alternative, practical method for welfare monitoring in zoos.

An analysis of valve re-replacement after aortic valve replacement with biologic devices

Biologic valve re-replacement was examined in a series of 1343 patients who underwent aortic valve replacement at The Prince Charles Hospital, Brisbane, with a cryopreserved or 4 degrees C stored allograft valve or a xenograft valve. A parametric model approach was used to simultaneously model the competing risks of death without re-replacement and re-replacement before death. One hundred eleven patients underwent a first re-replacement for a variety of reasons (69 patients with xenograft valves, 28 patients with 4 degrees C stored allograft valves, and 14 patients with cryopreserved allograft valves). By multivariable analysis younger age at operation was associated with xenograft, 4 degrees C stored allograft, and cryopreserved allograft valve re-replacement. However, this effect was examined in the context of longer survival of younger patients, which increases their exposure to the risk of re-replacement as compared with that in older patients whose decreased survival reduced their probability of requiring valve re-replacement. In patients older than 60 years at the time of aortic valve replacement, the probability of re-replacement (for any reason) before death was similar for xenografts and cryopreserved allograft valves but higher for 4 degrees C stored valves. However, in patients younger than 60 years, the probability of re-replacement at any time during the remainder of the life of the patient was lower with the cryopreserved allograft valve compared with the xenograft valve and 4 degrees C stored allografts.

Economic evaluation of high-dose and low-dose aprotinin therapy during cardiopulmonary bypass

BACKGROUND

Aprotinin therapy is now widely used during cardiac surgery. This study examined the clinical and economic effectiveness of high-dose or low-dose aprotinin in comparison to placebo.

METHODS

In a double blind, randomized study, three groups of 50 patients received high-dose aprotinin costing AUS$614 per patient (AUS$ = Australian dollars), low-dose aprotinin costing AUS$220 per patient or placebo. Resource use influenced by aprotinin therapy was measured.

RESULTS

Both doses were effective in reducing chest drainage and postoperative transfusion requirements, high-dose being more effective than low-dose. Both doses reduced the rate of reoperations for hemostasis. A base case of statistically significant differences associated with the high-dose and low-dose aprotinin showed cost savings of AUS$77 and AUS$348 per patient, respectively. If the demonstrated less significant reductions in operating room and ward stay are included, these savings become AUS$463 and AUS$715, respectively. Alternately, if cross-matches are replaced by group-and-hold and cell savers are not used, the savings per patient would be AUS$196 and AUS$467, respectively.

CONCLUSIONS

While high-dose aprotinin is clinically more effective than low-dose aprotinin, low-dose therapy demonstrates greater cost savings.

Mesenteric cysts--a series of six cases with a review of the literature

BACKGROUND

Symptomatic mesenteric cysts account for only 1 in 100,000 acute adult and 1 in 20,000 acute paediatric admissions. Acute symptoms are related to compression of intra-abdominal organs or stretching of the mesentery by rapid expansion. An abdominal mass, mobile in transverse but not longitudinal plane, is often the only physical finding.

METHOD

We outline the presentation, management and histological findings of 6 cases that presented to this hospital from 1987-1997.

RESULTS

There were 5 adults aged 32-79 yr and an 8 yr old boy. The child presented acutely with a painful tender abdominal mass. Of the adults, 1 presented acutely, 2 with chronic symptoms and 2 were incidental findings. Mesenteric cysts were successfully resected in all cases.

CONCLUSION

Surgical intervention is recommended and resection of adjacent bowel may be necessary for complete excision. Successful minimal access surgery via the laparoscope has been reported and may become more widely applicable.

Spondylolysis outcomes in adolescents after direct screw repair of the pars interarticularis

OBJECT

Isthmic spondylolysis can significantly decrease functional abilities, especially in adolescent athletes. Although treatment can range from observation to surgery, direct screw placement through the fractured pars, or Buck's procedure, may be a more minimally invasive procedure than the more common pedicle screw-hook construct.

METHODS

Review of surgical databases identified 16 consecutive patients treated with Buck's procedure from 2004 to 2010. Twelve patients were treated at Miami Children's Hospital and 4 at Barrow Neurological Institute. Demographics and clinical and radiographic outcomes were recorded and analyzed retrospectively.

RESULTS

The 16 patients had a median age of 16 years, and 14 were 20 years or younger at the time of treatment. Symptoms included axial back pain in 100% of patients with concomitant radiculopathy in 38%. Pars defects were bilateral in 81% and unilateral in 19% for a total of 29 pars defects treated using Buck's procedure. Autograft or allograft augmented with recombinant human bone morphogenetic protein as well as postoperative bracing was used in all cases. Postoperatively, symptoms resolved completely or partially in 15 patients (94%). Of 29 pars defects, healing was observed in 26 (89.6%) prior to 1 revision surgery, and an overall fusion rate of 97% was observed at last radiological follow-up. There were no implant failures. All 8 athletes in this group had returned to play at last follow-up.

CONCLUSIONS

Direct screw repair of the pars interarticularis defect as described in this series may provide a more minimally invasive treatment of adolescent patients with satisfactory clinical and radiological outcomes, including return to play of adolescent athletes.

Histologic characterization of acute spinal cord injury treated with intravenous methylprednisolone

OBJECTIVE

Many substances have been investigated for attenuation of spinal cord injury after acute trauma; however, pharmacologically only steroid administration has shown clinical benefits. This study attempts to characterize local spinal cord histologic response to human dose equivalent (HDE) intravenous methylprednisolone (MP) administration in a rodent model of acute spinal cord injury.

DESIGN

Forty-eight Sprague-Dawley rats were divided equally into control and experimental groups. Each group was subdivided into eight sets of three animals each, according to postinjury intervals. Paraplegia after lower thoracic laminectomy was achieved using a standardized weight drop technique.

INTERVENTION

Within one hour, experimental animals were treated with HDE MP followed by 23-hour continuous infusion of HDE MP. Spinal cords were harvested at variable intervals postinjury and prepared for histologic/immunohistochemistry examination.

MAIN OUTCOME MEASUREMENTS

Edema, necrosis, and glial fibrillary acidic protein (GFAP) positivity in the specimens from treated/control groups were graded by microscopy and immunohistochemistry staining and compared in a blinded manner by a qualified neuropathologist and senior authors.

RESULTS

Minimal differences were observed between control and MP-treated animals at zero and four hours. At eight hours, increased white matter and medullary edema was evident in control versus MP-treated rats. This trend continued through twelve, sixteen, twenty-four, forty-eight, and seventy-two hours. No difference was observed in the astrocytic response to injury by GFAP immunohistochemistry between the groups.

CONCLUSIONS

Histologically, MP reduces the development of severe edema and preserves spinal cord architecture adjacent to the site of injury. In contrast, MP does not alter the development of spinal cord necrosis or astrocytic response at the zone of injury.

Histologic and immunohistochemical responses after aortic valve allografts in the rat

BACKGROUND

Human aortic valve allografts elicit a cellular and humoral immune response. It is not clear whether this is important in promoting valve damage. We investigated the changes in morphology, cell populations, and major histocompatibility complex antigen distribution in the rat aortic valve allograft.

METHODS

Fresh heart valves from Lewis rats were transplanted into the abdominal aorta of DA rats. Valves from allografted, isografted, and presensitized recipient rats were examined serially with standard morphologic and immunohistochemical techniques.

RESULTS

In comparison with isografts, the allografts were infiltrated and thickened by increased numbers of CD4+ and CD8+ lymphocytes, macrophages, and fibroblasts. Thickening of the valve wall and leaflet and the density of the cellular infiltrate was particularly evident after presensitization. Endothelial cells were frequently absent in presensitized allografts whereas isografts had intact endothelium. Cellular major histocompatibility complex class I and II antigens in the allograft were substantially increased. A long-term allograft showed dense fibrosis and disruption of the media with scattered persisting donor cells.

CONCLUSIONS

The changes in these aortic valve allograft experiments are consistent with an allograft immune response and confirm that the response can damage aortic valve allograft tissue.

Root replacement for all allograft aortic valves: preferred technique or too radical?

From November 1985 to January 1994, 146 patients have received a viable cryopreserved allograft for aortic root replacement. The follow-up was complete, with all events included to March 1st, 1994. The median age of patients was 49 years; 83.6% were male. Valve dysfunction (91 patients), primary aortic wall disease (45 patients), and a combination of both (10 patients) were the indications for aortic root replacement. The current operative mortality is 1.7% (three deaths in 172 patients to July 1st, 1994). Four late deaths have occurred, with an 8-year actuarial survival of 85% +/- 8% (95% confidence limits). Endocarditis (two events) and thromboembolism (four events) had a low incidence. Structural deterioration (three events) and reoperation for all causes (nine events) have constituted low morbidity and are compared with the results after non-root allograft implantation techniques. The clinical and echocardiographic evidence indicates that the immediate results of valve function with root replacement are superior. But no statistical difference between aortic root replacement and non-root procedures is apparent at 8 years, indicating that a longer follow-up is required before the answer to the question "preferred technique or too radical" can be answered.

Rheumatoid arthritis of the cervical spine: current techniques for management

The incidence of rheumatoid arthritis in the European and North American population is significant. Rheumatoid arthritis can result in serious damage to the cervical spine and the central neuraxis, ranging from mild instability to myelopathy and death. Aggressive conservative care should be established early. The treating physician should not be lulled into a false sense of security by reports suggesting that cervical subluxations are typically asymptomatic [76-78]. Gradual spinal cord compression can result in severe neurologic deficits that may be irreversible despite appropriate surgical intervention when applied too late. [figure: see text] The treatment of rheumatoid disease in the cervical spine is challenging. Many details must be considered when diagnosing and attempting to institute a treatment plan, particularly surgical treatment. The pathomechanics may result in either instability or ankylosis. The superimposed deformities may be either fixed or mobile. The algorithm suggested by the authors can be used to navigate through the numerous details that must be considered to formulate a reasonable surgical plan. Although these patients are [figure: see text] frail, an "aggressive" surgical solution applied in a timely fashion yields better results than an incomplete or inappropriate surgical solution applied too late. When surgical intervention is anticipated, it should be performed before the development of severe myelopathy. Patients who progress to a Ranawat III-B status have a much higher morbidity and mortality rate associated with surgical intervention than do patients who ambulate. Although considered aggressive by some, "prophylactic" stabilization and fusion of a [figure: see text] relatively flexible, moderately deformed spine before the onset of severe neurologic symptoms may be reasonable. This approach ultimately may serve the patient better than "observation" if the patient is slowly drifting into a severe spinal deformity or shows signs of early myelopathy or paraparesis.