Surgical treatment of the painful motion segment: matching technology with indications

Instrumented Spinal Stabilization without Fusion for Spinal Metastatic Disease

OBJECTIVES

Spinal stabilization surgery is an integral part of the treatment of spinal metastatic disease. Bony fusion is the hallmark of spinal stabilization in non-oncology patients. Spinal oncology patients are unlikely to achieve bony fusion because of their overall prognosis and concurrent therapies. Stabilization surgery without fusion may be a reasonable approach for these patients. Literature evaluating the effectiveness of this approach is limited. The object of this study was to investigate the rate of instrumentation failure in patients undergoing posterior spinal instrumented stabilization without fusion for spinal metastatic disease.

METHODS

Data from consecutive cases of spinal surgery at our institution during an 81-month period were reviewed. Demographics, clinical notes, and computed tomography findings were recorded and used to evaluate instrumentation failures. Patients who underwent separation surgery that included laminectomy and posterior spinal instrumentation without fusion for spinal metastatic disease and had follow-up computed tomography scans >3 months postoperatively were selected for the study.

RESULTS

Twenty-seven patients were included in the study. Mean age was 64.85 ± 6.53 years. Nine patients were women. A mean of 1.61 ± 0.96 laminectomy levels was performed. A mean of 8.26 ± 1.48 screws was inserted. The mean postoperative discharge date was 5.07 ± 1.47 days. Mean follow-up duration was 12.17 ± 11.73 months. None of the patients had a change in instrumentation position, pedicle screw pullout, change in spinal alignment, or progressive deformity. No patient required reoperation or instrumentation revision or replacement.

CONCLUSIONS

Our experience suggests that instrumented spinal stabilization without fusion is an acceptable approach for patients with spinal metastatic disease.

Intraoperative platelet rich plasma usage in total knee arthroplasty: does it help?

Autologous platelet rich plasma preparations, commonly referred to as platelet gel, have been reported to have benefits when used in total knee replacement of less blood loss and better motion, with few reported complications. This retrospective review of 268 consecutive primary total knee arthroplasty cases compares postsurgical range of motion at 2, 8, and 12 weeks, knee manipulation rates, change in hemoglobin, and complications between one group receiving a platelet gel preparation (135 cases), and an equivalent group receiving no platelet gel preparation (133 control cases). No difference was found between groups in manipulation rates, knee range of motion, or changes in hemoglobin (P > 0.05). The use of platelet gel in this study did not have a significant effect on hemoglobin at 72 hours postoperatively, knee range of motion, or manipulation rates up to 3 months post-op in this patient cohort.

Retrograde ejaculation following single-level anterior lumbar surgery with or without recombinant human bone morphogenetic protein-2 in 5 randomized controlled trials: clinical article

OBJECT

The aim of this study was to determine the incidence and assess specific risk factors in the postoperative development of retrograde ejaculation (RE) in men treated for degenerative lumbar disc disease at the L4-5 or L5-S1 level with stand-alone anterior interbody implants with or without recombinant human bone morphogenetic protein-2 (rhBMP-2).

METHODS

Patients enrolled in 5 prospective, randomized, multicenter FDA-approved investigational device exemption studies were observed for a minimum of 2 years to assess the rate of RE. Five hundred eight men with symptomatic single-level lumbar degenerative disc disease with up to Grade 1 spondylolisthesis underwent anterior lumbar interbody surgery with stand-alone anterior implants at either L4-5 or L5-S1. All patient self-reported and physician-documented adverse events were recorded over the entire course of follow-up. In the investigational groups, 207 patients were treated with an open surgical procedure using dual paired constructs and rhBMP-2 on an absorbable collagen sponge. The control groups (n = 301) were treated with lumbar fusion cage implants and iliac crest autograft or a metal-on-metal disc arthroplasty device. Multivariate analyses of RE were performed to assess the influence of treatment (rhBMP-2), surgical approach, and treated level. Data were analyzed for each trial individually and for the data pooled from the 5 trials.

RESULTS

Retrograde ejaculation occurred at the highest rates in the earliest clinical trial. Of the 146 men, 6 (4.1%) developed RE postoperatively. In subsequent studies, the rates of RE ranged from 0% to 2.1%. Combining the data from the 5 trials, RE was reported in 7 (3.4%) of the 207 patients who received the rhBMP-2 treatment compared with 5 (1.7%) of the 301 patients who received the autograft or lumbar disc treatment (p = 0.242, Fisher exact test). Cases of RE were reported in 7 (1.6%) of 445 patients who underwent a retroperitoneal spinal exposure; 5 RE cases were reported in 58 patients (8.6%) who underwent a transperitoneal approach. The difference in surgical approaches was significant (p = 0.007, Fisher exact test). There was no difference in the rate of RE based on the lumbar level exposed (p = 0.739). Multivariate analyses were consistent with the conclusions from Fisher exact tests. In the initial rhBMP-2 trial, after adjusting for effects of surgical approach and treated level, the difference in RE between the treatment groups (rhBMP-2 vs autograft or disc arthroplasty) was not significant (p = 0.177); however, the difference in RE between the retroperitoneal and transperitoneal approaches was significant (p = 0.029).

CONCLUSIONS

In these 5 prospective randomized trials involving anterior lumbar interbody surgery, the use of rhBMP-2 was associated with a higher incidence of RE (3.4% vs 1.7%) but did not reach statistical significance. Based on surgical approach, the difference in rates of RE was statistically significant. This study reports on the outcomes of 5 prospective randomized FDA-approved investigational device exemption trials. Registration for studies became law in 2007. Four of these trials were completed before the law went into effect. The registration number for the lumbar disc arthroplasty trial is NCT00635843.

Differential effects of bone morphogenetic protein-2 and transforming growth factor-beta1 on gene expression of collagen-modifying enzymes in human adipose tissue-derived mesenchymal stem cells

Adipose tissue-derived mesenchymal stem cells (AT-MSCs) in combination with bone morphogenetic protein-2 (BMP-2) or transforming growth factor-beta1 (TGF-beta1) are under evaluation for bone tissue engineering. Posttranslational modification of type I collagen is essential for functional bone tissue with adequate physical and mechanical properties. We investigated whether BMP-2 (10-100 ng/mL) and/or TGF-beta1 (1-10 ng/mL) affect gene expression of alpha2(I) procollagen and collagen-modifying enzymes, that is, lysyl oxidase and lysyl hydroxylases 1, 2, and 3 (encoded by PLOD1, 2, and 3), by human AT-MSCs. BMP-2, but not TGF-beta1, increased alkaline phosphatase activity after 28 days, indicating osteogenic differentiation of AT-MSCs. At day 4, both BMP-2 and TGF-beta1 upregulated alpha2(I) procollagen and PLOD1, which was downregulated at day 28. TGF-beta1, but not BMP-2, downregulated PLOD3 at day 28. Lysyl oxidase was upregulated by TGF-beta1 at day 4 and by BMP-2 at day 7. Neither BMP-2 nor TGF-beta1 affected PLOD2. In conclusion, these results suggest that AT-MSCs differentially respond to BMP-2 and TGF-beta1 with changes in gene expression of collagen-modifying enzymes. AT-MSCs may thus be able to appropriately modify type I collagen to form a functional bone extracellular matrix for tissue engineering, dependent on the growth factor added.

Preparation of highly concentrated and white cell-poor platelet-rich plasma by plateletpheresis

BACKGROUND AND OBJECTIVES

Contaminating white blood cells (WBC) contribute remarkably to the overall growth factor content of locally applicable platelet-rich plasma (PRP) or platelet (PLT) gel and change the relative proportions of the contained growth factors.

MATERIALS AND METHODS

To study the independent effects of locally applicated highly concentrated PLTs, the development of preparations is needed that contain large amounts of PLTs and no or at least very few leucocytes. Therefore, 20 plateletpheresis procedures were performed in voluntary blood donors to get highly concentrated and extremely WBC-poor plateletpheresis concentrates. The degree of spontaneous PLT activation, the PLT aggregation response to agonists and the level of the growth factor TGF-beta1 (transforming growth factor beta1) were measured immediately after the donation and 1 day later.

RESULTS

The concentrates contained 1.96 +/- 0.36 x 10e11 PLTs per unit in 55.2 +/- 7.9 ml, respectively. In comparison to the donors' blood, the PLT-enrichment factor was 15.3 +/- 5.4. At the same time, the concentrates contained extremely low residual numbers of WBCs (0.8 +/- 3.3 x 10e3/ml). The concentration of the growth factor TGF-beta1 was 743.2 +/- 243.9 ng/ml. On day 1, the PLT concentration and the TGF-beta1 content of the PLT concentrates had not decreased.

CONCLUSIONS

In summary, plateletpheresis is suited to provide PRP products with higher concentrations of human platelets and platelet-derived growth factors than previously reported PRP preparation methods but with extremely low numbers of contaminating leucocytes.

Complication avoidance: thoracolumbar and lumbar burst fractures

Most thoracolumbar and lumbar burst fractures can be treated conservatively. Unstable fractures or fractures resulting in neurologic deficits usually require surgical treatment. Choosing an appropriate surgical approach requires a thorough understanding of the various techniques for decompression, fusion, and stabilization. Surgical options include an anterior approach, a posterior approach, or a combined anteroposterior approach. Each surgical option has unique advantages and disadvantages. Generally, the anterior approaches are best used at the thoracolumbar junction, posterior approaches are ideal for low lumbar injuries and lumbar injuries that result in complete spinal cord injuries,and anteroposterior surgeries typically are reserved for highly unstable fracture subluxations. Case illustrations show the various treatment options.

Decision-making in burst fractures of the thoracolumbar and lumbar spine

The most common site of injury to the spine is the thoracolumbar junction which is the mechanical transition junction between the rigid thoracic and the more flexible lumbar spine. The lumbar spine is another site which is more prone to injury. Absence of stabilizing articulations with the ribs, lordotic posture and more sagitally oriented facet joints are the most obvious explanations. Burst fractures of the spine account for 14% of all spinal injuries. Though common, thoracolumbar and lumbar burst fractures present a number of important treatment challenges. There has been substantial controversy related to the indications for nonoperative or operative management of these fractures. Disagreement also exists regarding the choice of the surgical approach. A large number of thoracolumbar and lumbar fractures can be treated conservatively while some fractures require surgery. Selecting an appropriate surgical option requires an in-depth understanding of the different methods of decompression, stabilization and/or fusion. Anterior surgery has the advantage of the greatest degree of canal decompression and offers the benefit of limiting the number of motion segments fused. These advantages come at the added cost of increased time for the surgery and the related morbidity of the surgical approach. Posterior surgery enjoys the advantage of being more familiar to the operating surgeons and can be an effective approach. However, the limitations of this approach include inadequate decompression, recurrence of the deformity and implant failure. Though many of the principles are the same, the treatment of low lumbar burst fractures requires some additional consideration due to the difficulty of approaching this region anteriorly. Avoiding complications of these surgeries are another important aspect and can be achieved by following an algorithmic approach to patient assessment, proper radiological examination and precision in decision-making regarding management. A detailed understanding of the mechanism of injury and their unique biomechanical propensities following various forms of treatment can help the spinal surgeon manage such patients effectively and prevent devastating complications.

Osteogenesis versus chondrogenesis by BMP-2 and BMP-7 in adipose stem cells

Bone morphogenetic proteins (BMPs) initiate, promote, and maintain chondrogenesis and osteogenesis. We hypothesize that BMP-2 induces an osteogenic, and BMP-7 a chondrogenic phenotype in adipose tissue-derived mesenchymal stem cells (AT-MSCs). We compared the effects of a short 15min BMP-2 or BMP-7 (10ng/ml) treatment on osteogenic and chondrogenic differentiation of AT-MSCs. Gene expression was studied 4 and 14 days after BMP-treatment. At day 4 BMP-2, but not BMP-7, stimulated runx-2 and osteopontin gene expression, and at day 14 BMP-7 down-regulated expression of these genes. At day 4 BMP-2 and BMP-7 stimulated biglycan gene expression, which was down-regulated by BMP-7 at day 14. BMP-7 stimulated aggrecan gene expression at day 14. Our data indicate that BMP-2 treatment for 15min induces osteogenic differentiation, whereas BMP-7 stimulates a chondrogenic phenotype of AT-MSCs. Therefore, AT-MSCs triggered for only 15min with BMP-2 or BMP-7 provide a feasible tool for bone and cartilage tissue engineering.