Anterior Transperitoneal Approach Research Articles

Pediatric case of presacral ganglioneuroma: diagnostic considerations and therapeutic strategy

BackgroundGanglioneuroma (GN) is an uncommon tumor belonging to the neuroblastic tumors group and is often localized in the posterior mediastinum, retroperitoneum, and adrenal gland. Presacral (PS) location is extremely rare. Its management remains a challenge.Case presentationA 4-year-old child presented to our department for an isolated abdominal mass. Para-clinical exams concluded to PSGN. Subtotal surgical excision was performed through an anterior transperitoneal approach. The size of the residual tumor did not progress after the 6-year follow-up period and the patients were asymptomatic.ConclusionsGN should be considered in the case of soft tissue presacral masses in pediatrics. Subtotal resection seems sufficient in case of an extension to the sacrum with low morbidity. The residual tumors are still stable and the prognosis seems conserved. Further, long-term follow-up in large studies is needed to confirm these findings.

Contemporary Techniques of Prostate Dissection for Robot-assisted Prostatectomy

BackgroundOver the years, several techniques for performing robot-assisted prostatectomy have been implemented in an effort to achieve optimal oncological and functional outcomes. ObjectiveTo provide an evidence-based description and video-based illustration of currently available dissection techniques for robotic prostatectomy. Design, setting, and participantsA literature search was performed to retrieve articles describing different surgical approaches and techniques for robot-assisted radical prostatectomy (RARP) and to analyze data supporting their use. Video material was provided by experts in the field to illustrate these approaches and techniques. Surgical procedureMultiple surgical approaches are available: extraperitoneal, transvesical, transperitoneal posterior, transperitoneal anterior, Retzius sparing, and transperineal. Surgical techniques for prostatic dissection sensu strictu are the following: omission of the endopelvic fascia dissection, bladder neck preservation, incremental nerve sparing by means of an antegrade or retrograde approach, and preservation of the puboprostatic ligaments and dorsal venous complex. Recently, techniques for total or partial prostatectomy have been described. MeasurementsDifferent surgical approaches and techniques for robotic prostatectomy have been analyzed. Results and limitationsTwo randomized controlled trials evaluating the extraperitoneal versus the transperitoneal approach have demonstrated similar results. Level I evidence on the Retzius-sparing approach demonstrated earlier return to continence than the traditional anterior approach. The question whether Retzius-sparing RARP is associated with a higher rate of positive surgical margins is still open due to the intrinsic bias in terms of surgical expertise in the available comparative studies. This technique also offers an advantage in patients who have received kidney transplantation. Retrospective evidence suggests that the more the anatomical dissection (eg., more periprostatic tissue is preserved), the better the functional outcome in terms of continence. Yet, two randomized controlled trials evaluating the different techniques of dissection have so far been produced. Partial prostatectomies should not be offered outside clinical trials. ConclusionsSeveral techniques and approaches are available for prostate dissection during RARP. While the Retzius-sparing approach seems to provide earlier return to continence than the traditional anterior transperitoneal approach, no technique has been proved to be superior to other(s) in terms of long-term outcomes in randomized studies. Patient summaryWe have summarized available approaches for the surgical treatment of prostate cancer. Specifically, we described the different techniques that can be adopted for the surgical removal of the prostate using robotic technology.

Surgical Indications and Techniques for Adrenalectomy.

Indications for adrenalectomy are malignancy suspicion or malignant tumors, non-functional tumors with the risk of malignancy and functional adrenal tumors. Regardless of the size of functional tumors, they have surgical indications. The hormone-secreting adrenal tumors in which adrenalectomy is indicated are as follows: Cushing’s syndrome, arises from hypersecretion of glucocorticoids produced in fasciculata adrenal cortex, Conn’s syndrome, arises from an hypersecretion of aldosterone produced by glomerulosa adrenal cortex, and Pheochromocytomas that arise from adrenal medulla and produce catecholamines. Sometimes, bilateral adrenalectomy may be required in Cushing’s disease due to pituitary or ectopic ACTH secretion. Adenomas arise from the reticularis layer of the adrenal cortex, which rarely releases too much adrenal androgen and estrogen, may also develop and have an indication for adrenalectomy. Adrenal surgery can be performed by laparoscopic or open technique. Today, laparoscopic adrenalectomy is the gold standard treatment in selected patients. Laparoscopic adrenalectomy can be performed transperitoneally or retroperitoneoscopically. Both approaches have their advantages and disadvantages. In the selection of the surgery type, the experience and habits of the surgeon are also important, along with the patient’s characteristics. The most common type of surgery performed in the world is laparoscopic transabdominal lateral adrenalectomy, which most surgeons are more familiar with. The laparoscopic anterior transperitoneal approach is the least preferred laparoscopic method in adrenalectomy. Retroperitoneal laparoscopic adrenalectomy can be performed with a posterior or lateral approach. In addition to conventional laparoscopy, laparoscopic surgery is robot-assisted, which can be administered by transperitoneal or retroperitoneal approach. In addition, conventional or robot-assisted laparoscopic adrenalectomy can be performed transabdominally or retroperitoneally using the single-port method. Today, partial adrenalectomy can be performed using laparoscopic techniques in bilateral adrenal masses, hereditary diseases with the risk of developing multiple adrenal tumors, and solitary masses of the adrenal gland. Open surgery is indicated in the case of malignancy or suspected malignancy and large tumors when laparoscopic surgery is contraindicated. The risk of conversion to open surgery is low (approximately 5%). The open transperitoneal anterior approach is the most common open intervention, especially in large tumors with malignancy or suspected malignancy. This procedure can be performed using a midline incision, bilateral or unilateral subcostal incision, Makuuchi or modified Makuuchi incision. Thoracoabdominal incision may be required, especially in the removal of large malignant lesions as a block. The open retroperitoneal approach can be applied posteriorly or laterally.

Are Adrenal Lesions of 6cm or More in Diameter a Contraindication to Laparoscopic Adrenalectomy? A Case-Control Study.

The aim of this case-control study is to compare the surgical outcomes of laparoscopic adrenalectomy (LA) for lesions measuring ≥6cm versus ≤5.9cm in diameter. Eighty-one patients with adrenal gland lesions ≥6cm in diameter (intervention group) were identified. Patients were matched to 81 patients with adrenal gland ≤5.9cm in diameter (control group) based on disease (Conn-Cushing syndrome, pheochromocytoma, primary or secondary adrenal cancer or other disease), lesion side (right, left), surgical technique (anterior transperitoneal approach for right and left LA or anterior transperitoneal submesocolic for left LA) and body mass index class (18-24.9, 25-29.9, 30-34.9, 35-39.9, ≥40kg/m2). Surgical outcomes were compared between the intervention and control groups. Mean operative time was statistically significantly longer in the interventional arm (101.4 ± 52.4 vs. and 85 ± 31.6min, p = 0.0174). Eight conversions were observed in the intervention group (9.8%) compared to four in the control group (4.9%) (p = 0.3690). Five (6.1%) and three (3.7%) postoperative complications were observed in the intervention and control groups, respectively (p = 0.7196). Mean postoperative hospital stay was 4.6 ± 2.4 and 4.1 ± 2.3days in the intervention and control groups, respectively (p = 0.1957). Operative time was statistically significantly longer in adrenal gland lesions ≥6cm in diameter (vs. ≤5.9cm). Conversion and complication rates were also higher, but the difference was not statistically significant. Based on the present data, adrenal gland lesions ≥6cm in diameter are not an absolute contraindication to the laparoscopic approach.

Laparoscopic bilateral anterior transperitoneal adrenalectomy: 24 years experience.

The aim of this study is to evaluate the feasibility, safety, advantages and surgical outcomes of laparoscopic bilateral adrenalectomy (LBA) by an anterior transperitoneal approach. From 1994 to 2018, 552 patients underwent laparoscopic adrenalectomy, unilateral in 531 and bilateral in 21 patients (9 females and 12 males). All patients who underwent LBA were approached via a transperitoneal anterior route and form our study population. Indications included: Cushing's disease (n = 11), pheochromocytoma (n = 6), Conn's disease (n = 3) and adrenal cysts (n = 1). Mean operative time was 195 ± 86.2min (range 55-360min). Conversion was necessary in one case for bleeding. Three patients underwent concurrent laparoscopic cholecystectomy with laparoscopic common bile duct exploration and ductal stone extraction in one. Three postoperative complications occurred in one patient each: subhepatic fluid collection, intestinal ileus and pleural effusion. Mean hospital stay was 6.1 ± 4.7 days (range 2-18 days). In our experience, transperitoneal anterior LBA was feasible and safe. Based on our results, we believe that this approach leads to prompt recognition of anatomical landmarks with early division of the main adrenal vein prior to any gland manipulation, with a low risk of bleeding and without the need to change patient position. Unlike the lateral approach, there is no need to mobilize the spleno-pancreatic complex on the left or the liver on the right. The ability to perform associated intraperitoneal procedures, if required, is an added benefit.

Robot-assisted multi-level anterior lumbar interbody fusion: an anatomical study.

Minimally invasive surgical approaches still provide limited exposure. Access to the L2-L5 intervertebral discs during a single procedure is challenging and often requires repositioning of the patient and adopting an alternative approach. Investigate the windows to the L2-L5 intervertebral discs to assess the dimensions of the interbody implants suitable for the procedure and evaluate the feasibility of multi-level lumbar intervertebral disc surgery in robot-assisted surgery (RAS) METHODS: Sixteen fresh-frozen cadaveric specimens underwent a retroperitoneal approach to access the L2-L5 intervertebral discs. The L2-L3 to L4-L5 windows were defined as the distance between the left lateral border of the aorta (or nearest common iliac vessel) and the medial border of the psoas, measured in a static state and after gentle medial retraction of the vascular structures. Two living porcine specimens and one cadaveric specimen underwent da Vinci robot-assisted transperitoneal approach to expose the L2-L3 to L4-L5 intervertebral discs and perform multi-level discectomy and interbody implant placement. The L2-L3 to L4-L5 intervertebral disc windows significantly increased from a static to a retracted state (p < 0.05). The mean L2-L3, L3-L4, and L4-L5 windows measured respectively 20.1, 21.6, and 19.6mm in the static state, and 27.2, 30.9, and 30.3mm after gentle vascular retraction. The intervertebral windows from L2-L3 to L4-L5 were successfully exposed through an anterior transperitoneal approach with the da Vinci robot on the cadaveric and living porcine specimens, and interbody implants were inserted. RAS appears to be feasible for a mini-invasive multi-level lumbar intervertebral disc surgery. The RAS procedure, longer and more expensive than conventional MIS approaches, should be reserved for elective patients.

Robot-assisted triple neurectomy for iatrogenic inguinal pain: a technical note

Painful neuromas are a relatively common complication of hernia and abdominal wall surgery. Surgical neurectomy has the potential to to provide durable relief for chronic pain; however, current surgical approaches are not without morbidity or anatomical challenges.We sought a surgical alternative. In the treatment of a case of incapacitating inguinal pain, we performed an anterior transperitoneal approach using a surgical robot. This approach was facile and provided elegant anatomical visualization. This case describes the first known robot-assisted laparoscopic triple neurectomy and details a simplified, transperitoneal approach.

The da Vinci Robotic Surgical Assisted Anterior Lumbar Interbody Fusion

Technique development to use the da Vince Robotic Surgical System for anterior lumbar interbody fusion at L5-S1 is detailed. A case report is also presented. To evaluate and develop the da Vinci robotic assisted laparoscopic anterior lumbar stand-alone interbody fusion procedure. Anterior lumbar interbody fusion is a common procedure associated with potential morbidity related to the surgical approach. The da Vinci robot provides intra-abdominal dissection and visualization advantages compared with the traditional open and laparoscopic approach. The surgical techniques for approach to the anterior lumbar spine using the da Vinci robot were developed and modified progressively beginning with operative models followed by placement of an interbody fusion cage in the living porcine model. Development continued to progress with placement of fusion cage in a human cadaver, completed first in the laboratory setting and then in the operating room. Finally, the first patient with fusion completed using the da Vinci robot-assisted approach is presented. The anterior transperitoneal approach to the lumbar spine is accomplished with enhanced visualization and dissection capability, with maintenance of pneumoperitoneum using the da Vinci robot. Blood loss is minimal. The visualization inside the disc space and surrounding structures was considered better than current open and laparoscopic techniques. The da Vinci robot Surgical System technique continues to develop and is now described for the transperitoneal approach to the anterior lumbar spine. 4.

Laparoscopic Surgery - A Feasible Treatment in Morris Syndrome

Morris Syndrome is a pathological condition which needs a special approach regarding both diagnosis and treatment because of its rarity. While the diagnosis is based on karyotype test, the treatment should follow the idea of harmless and cosmetic benefits as well as complete gonads removal. This paper is presenting the usefulness and advantages of minimally invasive surgery as a feasible treatment for such a disease. A retrospective study was performed for two patients with Morris Syndrome, admitted to the “CI Parhon” National Institute of Endocrinology, Bucharest, Romania, followed-up for 4 - 16 years, and operated to the Department of Surgery, Emergency Hospital, Bucharest, Romania. Patients with primary amenorrhea have been clinically observed and three patients with 46, XY karyotype have been identified as Morris Syndrome cases needing surgical removal of the intraperitoneal gonads because of the risk of malignant transformation. A minimally invasive surgical technique has been chosen for proper treatment: the anterior transperitoneal laparoscopic approach. The surgery was adapted to every case, in according with preoperative imagistic diagnosis of the intraperitoneal testes (localization, dimensions, adjacent organs involvement, surgical access). No postoperative complications were noticed and specimens' pathology confirmed the final diagnosis. Cosmetic benefits were achieved for every young patient as well as rapid postoperative recovery (discharge after 48 hours). The authors concluded that Morris Syndrome patients could benefit from the laparoscopic surgery which is a feasible, safe and proper treatment for such cases.

Successful Laparoscopic Exploration and Screw Extraction for Intrac Pain After Anterior Iliosacral Arthrodesis

We report on the case of a patient suffering from L5 radicular pain after previous anterior sacroiliac arthrodesis using 2, 4-hole plates. Technical investigations indicated loosening and migration of a screw from the upper sacroiliac plate, irritating the L5 nerve root. The problem was managed by removal of the screw using an anterior transperitoneal laparoscopic approach.

Laparoscopic nephrectomy in patients with renal vein and/or inferior vena cava anomalies: Video presentation

Laparoscopic nephrectomy is a standard surgery for the treatment of many types of renal tumor, renal pelvic tumor, and benign disease. Renal vein and inferior vena cava anomalies are not uncommon, having been detected at an incidence of 2-17%. With the increasing number of patients undergoing laparoscopic nephrectomy, surgeons have more opportunities to encounter major anomalies of the renal vein and inferior vena cava. This video presents images of the management of the renal pedicle in laparoscopic nephrectomy in cases where there were anomalies of the renal vein and inferior vena cava. Patient 1 had left renal tumor with the left inferior vena cava, patient 2 had left ureteral tumor with double inferior vena cava, patient 3 had left renal tumor with double inferior vena cava and a circumaortic renal vein, patient 4 had left renal tumor with a retro-aortic renal vein, and patient 5 had left renal tumor with a circumaortic renal vein. Multiple renal arteries were present in patients 3, 4, and 5. In laparoscopic nephrectomy complicated by anomalies of the renal vein and inferior vena cava, (i) surgical staff should be alert for the potential presence of aberrant veins and multiple renal arteries that may not be visualized in preoperative imaging. (ii) An anterior transperitoneal approach is well-suited in the understanding of positional relationships of vessels and anatomical landmarks in cases of vascular anomalies. (iii) With recent advances in diagnostic imaging modalities, such as multislice computed tomography (CT) and 3-D CT, it has become easier to identify the major arterial and venous anomalies. However, intraoperative observation and assessment remain important and mandatory in the management of smaller anomalous vessels accompanied by major anomalies.

ES07 *EXTRA‐ADRENAL PHEOCHROMOCYTOMA: IS THE “RULE OF 10” STILL APPLICABLE?

Background: The “rule of 10” is often used to described pheochromocytomas, with 10% extra‐adrenal, 10% malignant, 10% extra‐abdomen, 10% bilateral as well as 10% are found in patients who do not have hypertension and 10% are familial.Objective: To review the extra‐adrenal pheochromocytomas in our center and to establish whether the “rule of 10” is still applicable.Methods: Retrospective data were collected on all patients diagnosed to have extra‐adrenal pheochromocytomas (EAP) from January 1998 to December 2007 at our institution.Results: Over the last 10 years a total of 48 patients were diagnosed to have pheochromocytoma in our centre and 10 (20.8%) were documented to have EAP. The clinical presentation of 6(60%) patients was classical of pheochromocytoma with hypertension, headache, and palpitation, 2 (25%) patients had epigastric pain, 1(12.5%) with progressive weight loss and 1 (12.5%) with pregnancy induced hypertension. The EAP in all 10 patients were localized with CT scan or MRI. The anatomic locations of the EAP were as follows: 40% in the organ of Zuckerkandl, 30% adjacent to the adrenals, 20% along the renal vessels and 10% at the pre‐sacral area. All patients were explored via the anterior transperitoneal approach and histopathological report confirmed 9 (90%) were benign and 1(10%) malignant EAP.Conclusion: Our series demonstrates a higher incidence of 20.8% for EAP and 40% of them do not have hypertension. In addition, none of them had extra‐abdominal lesion. Therefore the study does not correlate with the “rule of 10” except the incidence of malignant EAP.

Laparoscopic Transperitoneal Right Adrenalectomy for ‘Large’ Tumors

Objectives: We compared two different approaches to right laparoscopic transperitoneal adrenalectomy for large tumors (>5 cm): the anterior transperitoneal (AT) and lateral transperitoneal (LT) approaches. Methods: 40 patients with a right large adrenal mass >5 cm underwent right adrenalectomy: 20 patients underwent the AT procedure and 20 patients the LT procedure. Preoperative characteristics were similar for both groups: mean tumor size for the AT and LT groups was 6.52 cm (range 5.2–8.5) and 6.59 cm (range 5.4–8.1), respectively. Mean patient’s age was 53 years (23–75 in the AT group and 20–77 in the LT group). AT and LT approaches were compared in terms of operative time, intraoperative blood loss, time to first oral intake and postoperative convalescence. Results: No difference was found between two groups in terms of estimated blood (100 ml for the AT group and 105.3 ml for the LT group), time to first oral intake (2.0 days for both groups) and convalescence (3.5 and 3 days, respectively). The mean operative times of the AT and LT procedures were 75.25 and 84.75 min, respectively: this difference was statistically significant at the Student’s t test (p = 0.0423). Conclusions: Both approaches proved to be safe and minimally invasive. We believe that the shorter operative time of AT procedures was related to the better visibility of familiar anatomic landmarks, easier access to the vessels and a larger operative field. For these reasons, we prefer the AT approach in the management of large adrenal masses.

Aortoiliac Occlusive Disease in the Presence of a Horseshoe Kidney: A Case Report

A case of aortoiliac occlusive disease in the presence of a horseshoe kidney anomaly is presented. The importance of careful preoperative planning by way of specialized investigations is stressed and the merits of both the anterior transperitoneal and retroperitoneal approaches to aortoiliac reconstruction in the presence of a horseshoe kidney are outlined.

Perioperative results of 214 laparoscopic adrenalectomies by anterior transperitoneal approach

The present study attempts to evaluate the perioperative results of the anterior approached laparoscopic adrenalectomy (LA) in a large cohort of patients, and report the advantages and disadvantages of this route. 204 patients, 125 female and 79 male with a mean age 52.8 years (range, 19-75 years), underwent LA by the anterior transperitoneal approach from 1994 to 2005 in our institution. There were 100 right and 114 left LAs. Ten patients underwent bilateral LA. Associated surgical procedures were performed in 17 cases. During the same period 47 LAs had been performed by different approaches (flank and submesocolic). Mean operative time was 80 minutes for right (40-150), 109 minutes for left (64-300) and 194 minutes for bilateral adrenalectomy. Intraoperative major complications were observed in six patients. Mortality occurred in one diabetic patient who was converted to open surgery because of a colonic perforation and subsequently developed a Candida sepsis in the postoperative course. The mean size of lesion removed was 6.2 cm (1.5-12 cm). Oral intake started within 24 hours and the mean hospital stay was 2.5 days (1-8 days). Histology results were as follows: nonsecreting adenoma 65, Cushing's adenoma 58, Conn's adenoma 53, pheochromocytoma 24, metastases 9, myelolipoma 3, adrenogenital syndrome 1, carcinoma 1. LA by anterior transperitoneal approach is safe and effective in our experience, despite the inherent limitation that this was not a prospective randomized study. The main advantage of this route is early ligature of the adrenal vein on both sides, enabling the performance of associated surgical procedures and bilateral adrenalectomy.

Adrenal incidentaloma: Surgical update

Nowadays, the role of surgery in the treatment of adrenal incidentalomas (AI), considering their biologic behavior, is still debated. Surgery is mandatory in cases of hyperfunctioning adrenal masses, in the presence of suspect radiological malignancy, in cases of discordant computed tomography (CT) and scintigraphy findings and when the maximum diameter is 4 cm or more. On the other hand, studies have suggested relative inaccuracy of conventional CT in evaluating the size. The aim of this paper was to evaluate the safety and effectiveness of laparoscopic adrenalectomy (LA) in the treatment of AI by reviewing our experience. Over the period from 1995 to 2005 we laparoscopically managed 78 AI by anterior transperitoneal approach. Two LA (2.6%) were converted to open surgery. Neither intra- nor post-operative major complications were observed. The mean size of lesions was 5.5 cm (range 3-9). Twenty-one large adrenal lesions (exceeding 6 cm) were removed (27%). Definitive histology resulted as follows: adrenocortical adenoma (63), pheochromocytoma (5), nodular hyperplasia (4), myelolipoma (3), cysts (2), and adrenocortical carcinoma (1, with a size of 3 cm). The patients were followed-up by hormonal and radiological evaluation every 12 months (6 for malignancy); their follow-up (median 60.4 months, range 6-123) was uneventful. Also larger AI were treated safely. Laparoscopy has been safe and effective in the treatment of AI in our experience, according to specific literature.

Hydronephrosis due to pelvi-ureteric obstruction in children. An assessment of the anterior transperitoneal approach

Abstract Twenty-four children (29 kidneys) with hydronephrosis due to pelvi-ureteric obstruction are reviewed. Conservative plastic surgery to the pelviureterc junction is recommended and an anterior transperitoneal approach to the renal pelvis is advocated. Extrarenal drainage should be used and pyelostomy or nephrostomy is not usually necessary. While the clinical results are excellent the radiological changes tend to be more disappointing and a longer follow-up period may be required to improve the radiological appearances.

Résection d’un schwannome rétropéritonéal en sablier par abord combiné

We report a remarkable case of retroperitoneal schwannoma with significant spinal growth illustrating the effectiveness of a combined surgical approach. A 41-year-old man presented with a long history of back pain and unexplained weight loss. An abdominal mass was found in the right upper quadrant. The CT-scan revealed a partially cystic lesion located in the right psoas muscle. Spinal extension was noticed through the L1-L2 neural foramen. MRI better showed the wide rostro-caudal extension in the spinal canal. Bilateral L1 and L2 laminectomy was performed to remove the spinal portion of the tumor. It was extradural but attached to the dura. The roots were not infiltrated. The retroperitoneal mass was removed by an anterior transperitoneal approach. The histological examination did not reveal criteria of malignancy. Retroperitoneal schwannomas are rare and their preoperative diagnosis remains difficult. In case of significant spinal growth, a combined surgical exposure should be preferred to allow total removal of the lesion and control of the neurological structures.

Analysis of porous ingrowth in intervertebral disc prostheses: a nonhuman primate model.

A study was conducted to investigate the biomechanical, histochemical, and biologic ingrowth characteristics of the most widely used total disc prosthesis, the hydroxyapatite-coated SB Charité prosthesis. To compare the porous ingrowth, linear apposition, or bony ingrowth in total disc replacement with published reports of porous ingrowth prostheses in the appendicular skeleton. Seven mature baboons (Papio cynocephalus) underwent L5-L6 total disc replacement through an anterior transperitoneal approach. The SB Charité prosthetic vertebral endplates (n = 14) were cobalt-chrome covered by two layers of thin titanium with a hydroxyapatite coating, which was electrochemically bonded to the implant surface. At 6 months after surgery, the range of motion exhibited by the SB Charité and the nonoperative control subjects under axial compression, flexion-extension, and lateral bending showed no statistical difference (P > 0.05). Plain film radiographic analysis showed no lucencies or loosening of any prosthetic vertebral endplate. Gross histopathologic analysis of the hydroxyapatite-coated SB Charité prosthesis demonstrated excellent ingrowth at the level of the implant-bone interface, without evidence of fibrous tissue or synovium. Histochemical assays showed no accumulation of particulate wear debris (no titanium, ultrahigh molecular weight polyethylene, or cobalt-chrome) nor cytokines (tumor necrosis factor-alpha, prostaglandin E2, interleukin-1, -2, or -6). Total endplate area showed a mean ingrowth (volume fraction) of 47.9% +/- 9.12% and a total ingrowth range of 35.5% to 58.8%. The porous ingrowth (percentage of pore ingrowth coverage at the bone-metal interface) was more favorable for total disc replacement than for cementless total joint components in the appendicular skeleton (range, 10-30%). The reason for the improved degree of porous ingrowth in total disc replacement prostheses probably is that ligamentotaxis causes sustained compression across the metal-bone interface.

Total disc replacement arthroplasty using the AcroFlex lumbar disc: a non-human primate model.

Using a non-human primate model, the current study was undertaken to investigate the efficacy of the AcroFlex lumbar disc as an intervertebral disc prosthesis, based on biomechanical, histopathologic and histomorphometric analyses. A total of 20 mature male baboons (Papio cynocephalus, mean weight 30 kg) were randomized into two equal groups based on post-operative time periods of 6 (n=10) and 12 months (n=10). Each animal underwent an anterior transperitoneal surgical approach to the lumbar spine, with intervertebral reconstructions performed at L3-L4 and L5-L6 using the following techniques: (1) tricortical iliac autograft and (2) AcroFlex lumbar disc. The two treatments were equally randomized between the non-contiguous operative lumbar levels. Post-mortem analysis included histopathologic assessment of the systemic reticuloendothelial tissues, multi-directional flexibility testing of the operative functional spinal units and quantitative histological analysis of trabecular bone coverage at the prosthesis endplates. Data were statistically compared using a one-way ANOVA with the Student-Newman-Keuls test. All animals survived the operative procedure and post-operative interval without significant intra- or peri-operative complications. Histopathologic analysis of the paraffin-embedded systemic reticuloendothelial tissues indicated no significant pathologic changes at the 6- or 12-month intervals. Plain film radiographic analysis showed no lucencies or loosening of any prosthetic vertebral endplate. Biomechanical testing of the 6-month autograft, reconstructions with AcroFlex lumbar disc and non-operative control (n=10) intact motion segments indicated no significant differences in peak range of motion (ROM) in axial compression. However, axial rotation produced significantly lower ROM for the autograft treatment compared to the intact and AcroFlex groups (P<0.05). The most significant differences in peak ROM were noted between all treatment groups under flexion/extension and lateral bending loading modalities (P<0.05). By 12 months, the intact condition indicated significantly more motion in all bending modes compared to the AcroFlex and autograft treatments, which were not statistically different from each other (P>0.05). Gross histopathologic analysis of the AcroFlex disc prosthesis demonstrated excellent ingrowth at the level of the implant-bone interface, without evidence of fibrous tissue or synovium. BioQuant histomorphometric analysis at the metal-bone interface (bone contact area/total endplate area) indicated the mean ingrowth was 54.59+/-13.24% at 6 months and 56.79+/-5.85% at 12 months. Radiographic analysis showed no lucencies or loosening of the AcroFlex vertebral endplate. Based on multi-directional flexibility testing, motion was preserved in axial rotation, but significantly diminished in the other bending modalities, particularly at the 12-month interval. This effect may be secondary to the limited surface area of device-vertebral endplate contact. Histomorphometric analysis of porous ingrowth coverage at the vertebral bone-metal interface was more favorable for total disc arthroplasty compared to historical reports of cementless femoral components. This project serves as the first comprehensive in vivo investigation into the AcroFlex disc prosthesis, and establishes an excellent research model in the evaluation of total disc replacement arthroplasty.