Complications of posterior lumbar interbody fusion when using a titanium threaded cage device.

OBJECT: The authors reviewed their series of patients to quantify clinical and radiographic complications in those who underwent a posterior lumbar interbody fusion (PLIF) procedure in which a threaded interbody cage (TIC) was implanted. METHODS: Sixty-seven patients underwent a posterior lumbar interbody fusion procedure in which a TIC was used. The authors excluded patients who underwent procedures in which other instrumentation was used or a nondorsal approach was performed. Fifteen percent of the cases (10 patients) were complicated by laceration of the dura. In three cases, bilateral implantation could not be performed. The average blood loss was 670 ml for all cases, and blood transfusion was required in 25% of the cases (17 patients). The rate of minor wound complication was 4.5% (three patients). One patient died. The average period of hospitalization was 4.25 days. Twenty-eight patients (42%) experienced significant low-back pain 3 months postoperatively, and in 10 (15%) of these cases it persisted beyond 1 year. In 10 patients postoperative radiculopathy was demonstrated, and magnetic resonance imaging revealed epidural fibrosis in six patients, arachnoiditis in one, and a recurrent disc herniation in one. One patient incurred a permanent motor deficit with sexual dysfunction. Pseudarthrosis was suggested radiographically with evidence of motion on lateral flexion-extension radiographs (10 cases), lucencies around the implants (seven cases), and posterior migration of the cage (two cases). Additional procedures (in 14 patients) consisted primarily of transverse process fusion with pedicle screw and plate augmentation for persistent back pain and radiographically demonstrated signs of spinal instability. In two patients with radiculopathy, migration of the TIC required that it be removed. Graft material that extruded from one implant necessitated its removal. In one patient scarectomy was performed. CONCLUSIONS: Our high incidence of TIC-related complications in PLIF is inconsistent with that reported in previous studies.

Secondary gain influences the outcome of lumbar but not cervical disc surgery.

BACKGROUND: The expectation of monetary compensation has been associated with poor outcomes in lumbar discectomy, fueling a reluctance among surgeons to treat worker's compensation cases. This issue, however, has not been investigated in patients undergoing cervical disc surgery. This study analyzes the relationship between economic forms of secondary gain and surgical outcome in a group of patients with common pay scales, retirement plans, and disability programs. METHODS: All procedures were performed at the Portsmouth Naval Medical Center between 1993 and 1995; active duty military servicepersons who were treated for cervical radiculopathy were prospectively included. Clinical, demographic, and financial factors were analyzed to determine which were predictive for outcome. Financial data were used to create a compensation incentive (CI) which is proportional to the rank, years of service, potential disability, retirement eligibility, and base pay and reflects the monetary incentive of disability. The results of cervical surgery were compared to a previously reported companion population of patients treated for lumbar disc disease. A good outcome is defined as a return to active duty, whereas a referral for disability is considered a poor surgical result. RESULTS: One hundred percent follow-up was obtained for 269 patients who were treated with 307 cervical operations. Only 16% (43/269) of cervical patients received disability, whereas 24.7% (86/348) of lumbar patients obtained a poor result (p = 0.0082). Although economic forms of secondary gain were not associated with outcome in cervical disease, both the position (p = 0.002) and duration of an individual's military career were significant factors (p = 0.02). Of the medical variables tested, multilevel surgery (p = 0.03) and revision operations at the same level (p = 0.03) were associated with referral for medical discharge. CONCLUSIONS: Secondary gain in the form of economic compensation influences outcome in lumbar but not cervical disc surgery; this observation may in part account for the success of cervical surgery relative to lumbar discectomy. Social factors that are independent of the anticipation of economic compensation seem to influence the outcome of cervical disc surgery.

A new technique for the surgical management of unstable thoracolumbar burst fractures: a modification of the anterior approach and an outcome comparison to traditional methods.

This study was conducted to determine the safety, efficacy, and complication rate associated with the anterior approach in the use of a new titanium mesh interbody fusion cage for the treatment of unstable thoracolumbar burst fractures. The experience with this technique is compared with the senior authors' (C.S., R.W., and M.S.) previously published results in the management of patients with unstable thoracolumbar burst fractures. Between 1996 and 1999, 21 patients with unstable thoracolumbar (T12-L3) burst fractures underwent an anterolateral decompressive procedure in which a titanium cage and Kaneda device were used. Eleven of the 21 patients had sustained a neurological deficit, and all patients improved at least one Frankel grade (average 1.2 grades). There was improvement in outcome in terms of blood loss, correction of kyphosis, and pain, as measured on the Denis Pain and Work Scale, in our current group of patients treated via an anterior approach when compared with the results in those who underwent a posterior approach. In our current study the anterior approach was demonstrated to be a safe and effective technique for the management of unstable thoracolumbar burst fractures. It offers superior results compared with the posterior approach. The addition of the new titanium mesh interbody cage to our previous anterior technique allows the patient's own bone to be harvested from the corpectomy site and used as a substrate for fusion, thereby obviating the need for iliac crest harvest. The use of the cage in association with the Kaneda device allows for improved correction of kyphosis and restoration of normal sagittal alignment in addition to improved functional outcomes.

The influence of secondary gain on surgical outcome: a comparison between cervical and lumbar discectomy.

Although the expectation of monetary compensation has been associated with failures in lumbar discectomy, the issue has not been investigated in patients undergoing cervical disc surgery. The authors analyzed the relationship between economic forms of secondary gain and surgical outcome in a group of patients with a common pay scale, retirement plan, and disability program. All procedures were performed at the Portsmouth Naval Medical Center between 1993 and 1995; active-duty military servicepersons treated for cervical radiculopathy were prospectively included. Clinical, demographic, and financial factors were analyzed to determine which were predictive of outcome. Financial data were used to create a compensation incentive, which is proportional to the patient's rank, years of service, potential disability, retirement eligibility, and base pay and reflects the monetary incentive of disability. The results of cervical surgery were compared to a previously reported companion population of patients treated for lumbar disc disease. A good outcome was defined as a return to active duty, whereas a referral for disability was considered a poor surgical result. A 100% follow-up rate was obtained for 269 patients who underwent 307 cervical operations. Only 16% (43 of 269) of patients who underwent cervical operation received disability, whereas 24.7% (86 of 348) of patients who underwent lumbar discectomy obtained a poor result (p = 0.0082). Although economic forms of secondary gain were not associated with a poor outcome in cervical disease, both the rank (p = 0.002) and duration (p = 0.03) of an individual's military career were significant factors (p = 0.02). Of the medical variables tested, multilevel surgery (p = 0.03) and revision operations at the same level (p = 0.03) were associated with referral for medical discharge. Secondary gain in the form of economic compensation influences outcome in lumbar but not cervical disc surgery patients; the increased rate of disability referral in patients who underwent lumbar discectomy may reflect an expectation of economic compensation. Social factors that are independent of the anticipation of economic compensation seem to influence the outcome in cervical disc surgery patients.

Surgical treatment of thoracolumbar fractures.

Many studies indicate that spinal canal decompression and stabilization lead to improved neurologic recovery in patients with incomplete neurologic deficits. It is recognized that surgical stabilization of unstable thoracolumbar injuries with complete neurologic deficit or without deficit reduces hospital stay, improves spinal alignment, shortens rehabilitation, and results in fewer medical complications. Unfortunately, many aspects of management remain controversial. For many injuries, more than one treatment method has been shown to be efficacious, although certain injuries have improved outcome with specific treatment modalities. This article is an overview of indications for surgery, operative approaches, types of instrumentation, and treatment options for specific thoracolumbar injuries.

Surgical approaches for the correction of unstable thoracolumbar burst fractures: a retrospective analysis of treatment outcomes.

The authors retrospectively studied 49 nonparaplegic patients who sustained acute unstable thoracolumbar burst fractures. All patients underwent surgical treatment and were followed for an average of 27 months. All but one patient achieved solid radiographic fusion. Three treatment groups were studied: the first group of 16 patients underwent anterior decompression and fusion with instrumentation; the second group of 27 patients underwent posterior decompression and fusion; and the third group of six patients had combined anterior-posterior surgery. Prior to surgical intervention, these groups were compared and found to be similar in age, gender, level of injury, percentage of canal compromise, neurological function, and kyphosis. Patients treated with posterior surgery had a statistically significant diminution in operative time and blood loss and number of units transfused. There were no significant intergroup differences when considering postoperative kyphotic correction, neurological function, pain assessment, or the ability to return to work. Posterior surgery was found to be as effective as anterior or anterior-posterior surgery when treating unstable thoracolumbar burst fractures. Posterior surgery, however, takes the least time, causes the least blood loss, and is the least expensive of the three procedures.

Characterization of tissue from the bone-polymethylmethacrylate interface in a rat experimental model. Demonstration of collagen-degrading activity and bone-resorbing potential.

In previous studies, we described a layer of tissue that formed around methylmethacrylate cement that had been implanted into the posterior cervical spine of dogs. We are now reporting on a rat model in which we induced, in the interface between the bone of the posterior elements of the dorsal spine and methylmethacrylate, the formation of a layer of tissue that was morphologically similar to the tissue that had been produced in the dogs. As in the dogs, we noted macrophages and giant cells and we demonstrated that the interface tissue synthesized several basement-membrane components (type-IV collagen, laminin, and fibronectin). In addition, we demonstrated the synthesis of an additional extracellular-matrix protein--type-VI collagen. We also showed that extracts of organ cultures of tissue from the rat model degraded type-I collagen into three-quarter and one-quarter-length fragments. Such enzymatic activity is characterized of mammalian collagenase, an enzyme that is known to play a critical role in the resorption of bone.

Nonunion of a midshaft clavicle fracture associated with subclavian vein compression. A case report.

Fractures of the clavicle are usually treated by closed means and heal uneventfully. In this report, we present an unusual case in which the subclavian vein was compressed by a fracture callus that had formed around a clavicular nonunion. Treatment included dissection of the subclavian vein from the fracture callus and compression plating with autogenous bone grafting of the fracture. Symptoms from the patient's venous obstruction slowly resolved without further treatment. The fracture united postoperatively.

Posterior cervical reconstruction with methyl methacrylate cement and wire: a clinical review.

The charts and radiographs of 20 patients who were treated for traumatic cervical instability by the Department of Neurosurgery at the University of Virginia by means of posterior reconstruction with methyl methacrylate cement and fixation wires were reviewed by the Department of Orthopaedic Surgery. Based primarily on radiographic criteria, it was found that posterior reconstruction failed to rigidly immobilize the underlying unstable motion segments in 11 patients. Four of these patients required additional surgery to correct postoperative instability. Based on this experience, cement and wire reconstructions are now recommended only when: 1) they can be limited to one cervical level; 2) No. 18 fixation wire is used; 3) wiring is performed from a facet on one side to the adjacent spinous processes; and 4) autogenous bone graft is added to the posterior elements on the side of the midline opposite the cement and wire.

Induction and characterization of an interface tissue by implantation of methylmethacrylate cement into the posterior part of the cervical spine of the dog.

After the implantation of methylmethacrylate cement into the posterior part of the cervical spine of the dog, a thick layer of connective tissue forms at the bone-cement interface. The tissue is six to eight millimeters thick and in all animals it surrounds the dorsal and lateral aspects of the masses of implanted cement, grows between the undersurface of the cement and the bone of the posterior elements, and completely covers that bone. This tissue was examined by light and electron microscopy and its collagenous components were extracted and analyzed biochemically by gel electrophoresis. Specific extracellular matrix proteins in the tissue at the bone-cement interface were also localized by immunohistochemistry. The tissue at the host-cement interface contained zones of fibrocytes and plump and teardrop-shaped cells within a collagenous matrix. Type-I, Type-III, and Type-V collagen were extracted and were identified by gel electrophoresis. Type-V collagen and fibronectin were localized predominantly around the plump and teardrop-shaped cells. Type-IV collagen and laminin were localized predominantly in an area just beneath the teardrop-shaped cells at the surface of the tissue overlying the cement, suggesting that a basement-membrane-like tissue had formed in this area.

Composite pelvic resection. An approach to advanced pelvic cancer.

The definition of resectability has changed in the management of advanced pelvic malignancy. Most tumors previously considered unresectable can be removed by a function-preserving composite resection of the pelvis. We have performed resection in 55 such patients. Most had posterior pelvic tumors (47 patients), had previously undergone irradiation, and required a combined sacral resection. Included were patients with recurrent or locally advanced rectal cancer (32 patients), epidermoid cancer of the anorectum (seven patients), and primary pelvic malignancies (eight patients). Most had good functional recovery. The five-year actuarial survival rate was 23% (five of 25 patients survived longer than 51 months) in the patients with resected rectal cancer and 14% (one of seven patients) in the patients with resected anorectal carcinoma. Five of eight patients with primary tumors survived longer than 48 months. Lateral pelvic resections were done for five tumors that involved the ileum or ischium, and anterior resection was done in three patients for malignancy that involved the symphysis and rami. Four of these patients were living three to six years after surgery. The overall mortality rate was 7% (four of 55 patients). Composite pelvic resections can provide good local control with preservation of limb function in most patients with primary or secondary tumors of the bony pelvis.

Cervical ligamentous instability in a canine in vivo model.

A canine in vivo model of midcervical ligamentous instability was developed by dividing the anterior longitudinal ligament, anulus fibrosus, and all posterior ligamentous structures including the ligamentum flavum. The natural history of healing in the model, the effect on its healing by an adjacent one-level arthrodesis, and the effect of a one-level arthrodesis on normal adjacent ligamentous structures were studied radiographically, mechanically, and histologically. The authors determined that healing takes place primarily by anterior scar formation in their instability model but not to a degree sufficient to recreate normal mechanical stability. After three months, healing in the model was not affected by an adjacent arthrodesis; however, acutely, instability apparently was increased as three animals became quadriplegic between the second and fourth postoperative days. Arthrodesis did not affect adjacent normal ligamentous structures, during this period. Incomplete healing in the authors' model supports those who advocate arthrodesis as the treatment of choice for destabilizing cervical ligamentous injury. The authors previously reported the case of a patient who sustained bilateral facet dislocations adjacent to an arthrodesed segment and questioned whether this resulted from a stress-concentrating effect. This study indicates that this could well have been the case acutely. Thus, inadvertent exclusion of an unstable segment from an arthrodesis has potentially catastrophic results. Finally, the authors also have previously questioned whether arthrodesis of a midcervical segment could lead to instability of adjacent normal segments. This project does not support such a concern, at least for the three postoperative months of study.

Pelvic recurrence of rectal cancer. Options for curative resection.

Pelvic recurrence is an ominous event after curative resection of rectal cancer and is rarely amenable to re-resection by conventional methods. A method to permit a composite resection of these using the abdominal sacral approach has been described previously. This report updates that experience with resection of pelvic recurrence of rectal cancer in 28 patients. Of these, 24 were done with curative intent, and four were done for palliation (mainly for infected or fungating tumor). All patients had extensive preoperative evaluation by clinical and radiologic tests, and most patients had a long free interval period of approximately 18 months, after their primary resection. Although 47 patients had exploratory surgery, only 29 had local disease amenable to resection and four had palliative resections. About half the patients had had an abdominoperineal resection, half had had an anterior resection, and one third had had previous efforts to resect the recurrence. All but one patient had been irradiated with 3000-11,000 cGy. All but two patients (of the 24 curative efforts) required a formal abdominosacral resection (through S1-2 in 12, S2-3 in 9, and S4-5 in 1). Over half the patients also required a bladder resection. There were three operative deaths (12%); one patient had a cardiac death immediately after operation and two were septic deaths at 35 and 60 days. The survivors generally had relief of sacral root pain and good motor function; most of those previously employed could return to work. The actuarial 5-year survival rate is 25% and median survival is 36 months. Long-term survival over 48 months was recorded in five of 21 surgical survivors (23.8%). Survival in a historic comparative group of 30 patients treated for local recurrence only (mainly by radiation) was 15 months median, and at 5 years the survival rate was 3% (p less than 0.001). In conclusion, selected patients with pelvic recurrence of rectal cancer may be retrieved by and returned to functional life with the composite abdominosacral resection.

Posterior cervical fusions using cerclage wires, methylmethacrylate cement and autogenous bone graft. An experimental study of a canine model.

UNLABELLED: Forty-eight adult mongrel dogs underwent posterior exposure of C4-C5, fixation of the two posterior spinous processes together with a no. 20-gauge cerclage wire, posterior element decortication, wound irrigation and the following: bone fusions (application of a standard volume of iliac crest autograft), polymethylmethacrylate (PMMA) fusions (application of a standard volume of methylmethacrylate cement), Combination 1 fusions (application of one-half the volume of graft used in the bone fusions, over the facet joints. Methylmethacrylate cement was pressed into position centrally to surround the posterior spinous processes and cerclage wire), Combination 2 fusions (application of the same volume of graft used in the bone fusions, over the facet joints. Methylmethacrylate cement was applied as in the Combination 1 fusions). For each preparation, six animals survived 2 weeks or 3 months. All had monthly lateral cervical radiographs. At the appropriate times, they were killed and their C4-C5 segments excised and studied mechanically and histologically. At 2 weeks all of the above preparations were mechanically inferior to normal C4-C5 segments in respect to at least one of the parameters studied. At 3 months, the bone fusions and both combination fusions had developed sufficient mechanical stability so that they were equivalent to normal segments. At this time, the PMMA fusions remained inferior to the "normals." The mechanical data for the PMMA and both combination fusions was corroborated by the histology which demonstrated a fibrosynovial layer between the cement masses and underlying posterior element bone. In the 3-month combination fusions, the lateral aspects of the posterior elements had been spanned by a fusion mass. CLINICAL RELEVANCE: Previously, the authors defined some of the problems associated with constructs modeled by their PMMA fusions. This work confirms the previous research. It also demonstrates that ultimate spinal stability is produced by combination constructs. Because of the 2-week mechanical data, it is recommended that when combination constructs are used clinically, the patient's neck be protected by an external orthosis in the early postoperative period.

Complications associated with the halo-vest. A review of 245 cases.

The cases of all patients treated with halo-vests for cervical trauma at the University of Virginia since 1977 were analyzed retrospectively. A standardized chart and radiographic review protocol were used to identify complications associated with the use of the orthosis. Two hundred and forty-five patients satisfied the criteria for inclusion in the study. No patient developed or suffered progression of a neurological deficit while immobilized. Complications included: pneumonia causing death (one patient); loss of reduction or progression of the spinal deformity (23 patients); spinal instability following orthotic immobilization for 3 months (24 patients); pin-track infection (13 patients); migration of anteriorly placed iliac-strut grafts (two patients); cerebrospinal fluid leakage from a halo pinhole (one patient); and miscellaneous (seven patients). The findings indicate several conclusions. The halo-vest protects patients with cervical instability from neurological injury. It does not absolutely immobilize the cervical spine nor does it prevent progressive deformity of malpositioned strut grafts. Even after a 3-month orthotic treatment period, surgery may be required on ligamentous and osseous injuries to provide spinal stability. Elderly kyphotic patients may require custom-made vests. A small subset of patients exists for whom the confining nature of the halo-vest is intolerable for 3 months.