Topic Editor Regis W. Haid
Invited submission from the Joint Section Meeting on Disorders of the Spine and Peripheral Nerves, March 2004
Praveen V. Mummaneni and Regis W. Haid
✓ In the past 50 years tremendous advances have been made in the treatment of cervical disc disease with cervical fusion. Fusion rates have surpassed 95% after application of anterior cervical implants. Adjacent-segment degeneration, however, has plagued the long-term clinical success of cervical fusion.
Cervical arthroplasty has been introduced to maintain cervical motion and potentially avoid or minimize adjacent-segment degeneration. If cervical arthroplasty is successful, the long-term results of surgery for cervical disc disease may improve; however, there are associated drawbacks that must be overcome. Implant wear, fatigue, and failure have been reported in cases of large-joint arthroplasty, and research is underway to limit these problems in cervical arthroplasty.
In this article the authors trace the evolution of cervical fusion and the new technique of cervical arthroplasty. The nomenclature of cervical arthroplasty will also be introduced.
Harel Deutsch, Regis W. Haid, Gerald E. Rodts, and Praveen V. Mummaneni
Postlaminectomy cervical kyphosis is an important consideration when performing surgery. Identifying factors predisposing to postoperative deformity is essential. The goal is to prevent postlaminectomy cervical kyphosis while exposing the patient to minimal additional morbidity. When postlaminectomy kyphosis does occur, surgical correction is often required and performed via an anterior, posterior, or combined approach. The authors discuss the indications for surgical approaches as well as clinical results.
Regis W. Haid, Kevin T. Foley, Gerald E. Rodts, and Bryan Barnes
The authors review historical and biomechanical aspects of anterior cervical plate (ACP) systems. They propose a novel classification system for ACPs based on the biomechanical and graft-loading properties of these systems.
A retrospective review of the literature comprising both clinical and laboratory investigations regarding the ACP system was undertaken. Comparison of each system is considered in the context of the biomechanical attributes and graft-loading properties of each type of plate. Salient characteristics reviewed include restriction of screw backout, screw-angle variability, and mobility at the screw–plate interface. A new classification system for ACPs is proposed that primarily considers the ability of the construct to restrict screw backout, as well as the properties of the plate–screw interface—that is, the capacity for rotational or translational movement.
A new classification system is presented that provides unified, biomechanically descriptive nomenclature. Using this nomenclature, the ACP devices currently available and those developed in the future can be uniformly categorized.
Brian R. Subach, Regis W. Haid, Gerald E. Rodts, and Michael G. Kaiser
The widespread use of fusion procedures in the management of spinal disorders has led investigators to explore the use of growth and differentiation factors in such procedures. As an adjuvant to allograft bone or as a replacement for harvested autograft, bone morphogenetic proteins (BMPs) appear to improve fusion rates after spinal arthrodesis in both animal models and humans, while reducing the donor-site morbidity previously associated with such procedures. The use of recombinant genetic technology in the production of BMP has improved the efficiency, cost effectiveness, and safety of producing and using such materials. Recombinant human BMP-2 (rhBMP-2), as one of the first factors identified in the process of endochondral bone formation, has been extensively researched over the past decade. The efficacy and dose profile of this differentiation factor in the context of various carrier substrates has been investigated. Based on the encouraging results of preliminary studies, the future role of rhBMP-2 may lie in its replacement of autologous bone grafting and, consequently, the reduced need for instrumented fixation, while concurrently improving overall fusion rates. The authors provide an overview of BMP and review its use in clinical and laboratory settings.
Praveen V. Mummaneni, Valli P. Mummaneni, Regis W. Haid Jr., Gerald E. Rodts Jr., and Rick C. Sasso
The correction of chin-on-chest deformity is challenging and requires combined anterior and posterior approaches to the cervical spine. The authors describe a cervical osteotomy technique for the correction of chin-on-chest deformity in patients with ankylosing spondylitis (AS). This procedure can be accomplished using a posterior screw rod construct combined with an anterior hybrid plate system.
In patients with AS, a “front-back-front” approach may be necessary because of the deformity's rigidity. The authors describe the complicated intubation and anesthetic requirements for this approach. They performed an anterior discectomy, cervical osteotomy, and unilateral pediculectomy but did not place anterior instrumentation. Via a posterior approach, laminectomies, facetectomies, and the contralateral pediculectomy were then undertaken. A posterior cervical screw/rod system was placed and loosely connected to titanium rods. Intraoperatively the deformity was corrected by placing the neck in extension combined with compression of the posterior screws on the rods. The posterior construct is then tightened. Finally, an anterior cervical approach is performed to place a structural interbody graft and a hybrid anterior cervical plate construct.
The authors have successfully used this approach to correct a chin-on-chest deformity in a patient with ankylosing spondylitis. At 1-year follow-up examination, excellent resolution of the deformity and solid fusion had been achieved. They prefer to perform this procedure by using state-of-the-art anterior and posterior instrumentation systems.
Harel Deutsch, Praveen V. Mummaneni, Regis W. Haid, Gerald E. Rodts, and Stephen L. Ondra
Primary tumors of the sacrum are rare. In adults, the most common sacral tumors are metastases. The most common primary sacral tumor is a chordoma. Chordomas along as well as tumors such as chondrosarcomas, osteosarcomas, myxopapillary ependymomas, myelomas, and Ewing sarcomas are considered malignant. In this article the authors focus on benign sacral tumors.
Mark R. McLaughlin, Jonathan Y. Zhang, Brian R. Subach, Regis W. Haid Jr., and Gerald E. Rodts Jr.
In recent years, there has been an unprecedented increase in the number of patients undergoing treatment with interbody fusion devices for degenerative disease of the lumbar spine. These devices can be placed either anteriorly or posteriorly. With the advent of minimally invasive surgery and the increasing ability of general surgeons to perform transperitoneal procedures laparoscopically, a new laparoscopic technique has been developed for placing lumbar interbody fusion devices. Although this procedure has some advantages over posterior lumbar interbody fusion, it is not without significant risk, and the learning curve is steep. The authors review a series of 32 consecutive patients who underwent single-level laparoscopic anterior lumbar interbody fusion at L4–5 or L5–S1 over a 2-year period for the treatment of single-level lumbar degenerative disease. In this report they review the technical aspects of the procedure and the important lessons they have learned through their early experience with this technique.
Bryan Barnes, Mark R. McLaughlin, Barry Birch, Gerald E. Rodts Jr., and Regis W. Haid Jr.
The authors retrospectively reviewed a series of cases involving mechanical low-back or disogenic pain; 35 patients underwent lumbar interbody fusion in which threaded cortical bone dowels (TCBDs) were placed to treat degenerative disc disease.
The series was composed of 18 females, and 17 males whose mean age was 46 years (range 17-76 years). There were nine smokers in the group. All patients presented with symptoms consistent with mechanical low-back or discogenic pain, and magnetic resonance imaging–documented degenerative changes and disc collapse greater than 50%, as compared with the adjacent normal-appearing level, were confirmed. Twenty-three patients underwent a posterior lumbar interbody fusion (PLIF) procedure for placement of the TCBD, whereas 12 underwent an anterior lumbar interbody fusion (ALIF) procedure for placement of the TCBD. In all patients undergoing PLIF procedures pedicle screw and rod constructs were used without posterolateral fusion except one. In all cases of ALIF except one TCBDs were used as “stand-alone” devices without supplemental fixation. All TCBDs were packed with morselized cancellous autograft prior to implantation. The success of fusion was determined at follow-up intervals and was defined as: the absence of lucency around the TCBD; an increase in subchondral endplate sclerosis; and the presence of bridging bone incorporating the anterior bone graft as demonstrated on static lumbar radiographs and/or computerized tomography scans. Stability was also determined by an absence of movement on dynamic lumbar radiographs. The degree of lumbar lordosis at the diseased level was measured immediately postoperatively and compared with the change in lordosis at follow up. Outcomes were assessed using a modified Prolo outcome scale and rated as excellent, good, fair, or poor. Excellent and good outcomes were considered satisfactory; fair or poor outcomes were considered unsatisfactory.
In 27 patients radiographic and clinical follow-up results were considered adequate (nine ALIF and 18 PLIF patients). The mean follow-up duration was 7.9 months. Overall satisfactory outcome was 70%: a 77% satisfactory outcome in PLIF patients and a 55% in ALIF patients. Osseous fusion was present in 94% of the patients in the PLIF group and in 33% of those in the ALIF group. Complications included one L-5 nerve root injury and two postoperative wound infections, all in patients who underwent PLIF; there was also a case of breakout of one implant at 8 months postoperatively. The degree of vertebral body angulation measured at last follow up compared with the measurement obtained immediately postoperative was 3.4° of kyphosis in the ALIF group and 3.1° of kyphosis in the PLIF group, which represented an 11% and 9% loss of lordosis, respectively.
Preliminary results indicate that there is a dramatically higher fusion rate in PLIF compared with ALIF procedures in which TCBDs are used. There is a corresponding trend seen in patient outcomes, but no distinct difference seems apparent in terms of restoration of lordosis when performing either procedure. The results suggest that TCBDs may best be used in PLIF procedures in conjunction with pedicle screws and rod constructs. Moreover, in patients in whom TCBDs and supplemental tension band constructs are used fusion rates appear to be comparable with those reported in other series but at a faster rate (94% at 7.9 months mean follow up). Longer follow-up periods and a larger series of patients are needed to confirm these preliminary observations.