Scott Kitchel

Results of the prospective, randomized, multicenter Food and Drug Administration investigational device exemption study of the ProDisc-L total disc replacement versus circumferential fusion for the treatment of 1-level degenerative disc disease.

Study Design. A prospective, randomized, multicenter, Food and Drug Administration-regulated Investigational Device Exemption clinical trial. Objective. To evaluate the safety and effectiveness of the ProDisc®-L (Synthes Spine, West Chester, PA) lumbar total disc replacement compared to circumferential spinal fusion for the treatment of discogenic pain at 1 vertebral level between L3 and S1. Summary of Background Data. As part of the Investigational Device Exemption clinical trial, favorable single center results of lumbar total disc replacement with the ProDisc®-L have been reported previously. Methods. Two hundred eighty-six (286) patients were treated on protocol. Patients were evaluated before and after surgery, at 6 weeks, 3, 6, 12, 18, and 24 months. Evaluation at each visit included patient self-assessments, physical and neurologic examinations, and radiographic evaluation. Results. Safety of ProDisc®-L implantation was demonstrated with 0% major complications. At 24 months, 91.8% of investigational and 84.5% of control patients reported improvement in the Oswestry Low Back Pain Disability Questionnaire (Oswestry Disability Index [ODI]) from preoperative levels, and 77.2% of investigational and 64.8% of control patients met the ≥15% Oswestry Disability Index improvement criteria. Overall neurologic success in the investigational group was superior to the control group (91.2% investigational and 81.4% control; P = 0.0341). At 6 weeks and 3 months follow-up time points, the ProDisc®-L patients recorded SF-36 Health Survey scores significantly higher than the control group (P = 0.018, P = 0.0036, respectively). The visual analog scale pain assessment showed statistically significant improvement from preoperative levels regardless of treatment (P < 0.0001). Visual analog scale patient satisfaction at 24 months showed a statistically significant difference favoring investigational patients over the control group (P = 0.015). Radiographic range of motion was maintained within a normal functional range in 93.7% of investigational patients and averaged 7.7°. Conclusions. ProDisc®-L has been found to be safe and efficacious. In properly chosen patients, ProDisc®-L has been shown to be superior to circumferential fusion by multiple clinical criteria.

The use of bioabsorbable implants in the spine

BACKGROUND CONTEXT Bioabsorbable implants are commonplace in sports medicine surgeries, especially in shoulder and knee ligamentous reconstruction. Their use is now expanding to the realm of spinal reconstructive surgery. Newer polymers offer reduced incidence of the side effects of aseptic sterile sinus formation and have appropriate resorption time parameters for spine use. These new bioabsorbable materials confer initial and intermediate-term stability that is adequate for stable bony healing in various applications. The majority of human clinical applications in the spine that have been documented involve bone graft harvest site reconstruction, posterior spinal graft containment, anterior interbody reconstruction and anterior cervical and lumbar spine tension band plating. PURPOSE The purpose of this review article is to highlight the indications and outcomes of the use of bioabsorbable implants in specific spinal applications. STUDY DESIGN A comprehensive literature review of the English and non-English literature on bioabsorbable implant technology. METHODS A comprehensive literature review was performed to gather basic science, animal and human data on the use of bioabsorbable implants in spinal surgery. RESULTS Bioabsorbable implants have demonstrated strength and resorption characteristics commensurate with the physiologic and biomechanical requirements of the human spinal axis. Histologic sampling has demonstrated successful time-patterned resorption accompanied by bony replacement and remodeling of intervertebral cage devices in the animal model. CONCLUSION Bioresorbable compounds appear to have a role in specific spinal reconstructive procedures. Their radiolucent nature improves image assessment of fusion healing, and their time-engineered resorption characteristics allow controlled dynamization in interbody and plate applications. Their widespread use and acceptance may increase dramatically as further research and clinical studies report on their safety and efficacy.

Techniques for Aspirating Bone Marrow for Use in Spinal Surgery

OBJECTIVE: The osteogenicity of bone marrow has been well documented in the literature. The use of bone marrow as a source of osteoprogenitor cells for spinal fusion surgery is increasing. Improper aspiration technique can lead to dilution of bone marrow and a subsequent reduction in osteoprogenitor cells. Therefore, correct aspiration technique is imperative to the successful use of bone marrow with various grafting combinations. METHODS: The authors describe techniques for aspirating bone marrow from the anterior and posterior iliac crest, as well as vertebral body aspiration. The use of selective cell retention to increase the number of osteoprogenitor cells populating a graft is also described. RESULTS: Complications from bone marrow aspiration can occur, but the incidence is rare. CONCLUSION: Clinical studies currently under way will answer the question of bone marrow efficacy in spinal fusion surgery.

Comparison of stiffness and failure load of two cervical spine fixation techniques in an in vitro human model

Objective: Recently, an unpaired threaded cage has been introduced as a fusion device for the cervical spine. No biomechanical comparison of a stand-alone single interbody threaded cage to a standard plated Smith-Robinson construct has been reported. Accordingly, an in vitro biomechanical comparison of a single threaded cylindrical interbody fusion cage versus a plated Smith-Robinson cervical discectomy and fusion construct was conducted to establish whether a single cylindrical interbody cage in the cervical spine would perform mechanically as well as a plated structural interbody graft. Methods: Six fresh-frozen human cadaveric cervical spines were used for biomechanical testing. Flexion-extension and load-to-failure testing were performed on two single-level discectomy and interbody fusion constructs from each specimen. Results: Initial range of motion (ROM) was significantly greater for the specimens implanted with a cage than specimens implanted with a structural graft and plate (9.1° ± 3.7° vs 5.8° ± 2.4°; P = 0.040). Initial stiffness in flexion in caged specimens was significantly less than in plated specimens (0.7 ± 0.3 vs 0.9 ± 0.3 Nm/°; P = 0.028). Cage specimens also failed at a significantly lower load than plated specimens (9.8 ± 3.5 vs 15.8 ± 4.1 Nm; P = 0.0104). Conclusions: This study demonstrates that a plated Smith-Robinson cervical discectomy and fusion construct provides greater stiffness and failure load and reduced ROM across operated levels than a single interbody cage construct. Although clinical success may not directly correlate with biomechanical data, these results raise concern regarding the use of a single threaded interbody cage as a stand-alone device for cervical interbody fusion.

Sacroiliac Joint Pain and Its Treatment.

The sacroiliac joint (SIJ) as a source of symptoms has been controversial; however, as knowledge about the joint increased, its role as a pain generator in patients complaining of symptoms that are often attributed to spinal pathology has become better appreciated. The literature reports that the SIJ is the pain origin in as many as 30% of patients presenting with low back pain. Clinically, the SIJ can be challenging to evaluate; however, assessing pain location, patient posture/movement, and provocative manual testing are useful in making the presumptive diagnosis of SIJ disruption. The most definitive evaluation is image-guided injection of anesthetic solutions into the joint which is diagnostic if there is at least 75% symptom relief acutely. Treatment begins with nonoperative intervention including physical therapy and/or chiropractic care. If these fail, the next option is generally radiofrequency denervation (rhizotomy) of the joint. If this does not provide adequate relief, surgical intervention, in the form of minimally invasive SIJ fusion may be considered. The literature increasingly supports favorable results of SIJ fusion in appropriately selected patients. The purpose of this review is to provide an overview of the current literature on the SIJ, with focus on its surgical treatment.

Comparison of subsidence failure between a cervical cage and a cortical allograft in a human cadaveric model

Interbody fusion (IBF) is an accepted procedure for the treatment of single-level cervical disc disease. The goal of interbody fusion in the cervical spine is to restore disc height and achieve solid arthrodesis; however, a concern with IBF devices is subsidence. The purpose of this study was to biomechanically test and compare subsidence between two cervical interbody fusion techniques, under axial compressive loading in a human cadaveric cervical model.Copyright