Anil Sethi

Complications in the Use of rhBMP-2 in PEEK Cages for Interbody Spinal Fusions

Study Design All patients of spinal interbody fusion using polyetheretherketone (PEEK) cages and recombinant human bone morphogenetic protein (rhBMP)-2 performed over a 16-month period were reviewed. Objective To determine the suitability of PEEK cages when used in conjunction with rhBMP-2 in interbody spinal fusion. Summary of Background Data Bone morphogenetic proteins are increasingly being used in spinal fusion to promote osteogenesis. PEEK is a semicrystalline aromatic polymer that is used as a structural spacer to maintain the disc and foraminal height. Their use has led to increased and predictable rates of fusion. However, not many reports of the adverse effects of their use are available. Methods Fifty-nine consecutive patients of interbody spinal fusion in the cervical or lumbar spine using a PEEK cage and rhBMP-2 were followed for an average of 26 months after surgery. A clinical examination and a record of Oswestry Disability Index, Visual Analog Scale for pain, and a pain diagram were performed preoperatively and at every follow-up visit. All patients had plain radiographs carried out to assess fusion. Ten patients of lumbar spine fusion were additionally evaluated with a computed tomography scan. Results All cases demonstrated an appreciable amount of new bone formation by 6 to 9 months in the cervical spine and by 9 to 12 months in the lumbar spine. End plate resorption was visible radiologically in all cervical spine fusions and majority of lumbar fusions. Cage migration was observed to occur maximally in patients with transforaminal lumbar interbody fusion and posterior lumbar interbody fusion. Disc space subsidence was seen in both cervical and lumbar arthrodesis with the latter showing a lesser incidence, but with a greater degree of collapse. Conclusions PEEK cages and rhBMP-2 when used in spinal fusion give consistently good fusion rates. However, the early role of BMP in the resorptive phase may cause loosening, cage migration, and subsidence.

Lumbar Spine Fusion in Obese and Morbidly Obese Patients

Study Design. Single-center retrospective study. Objective. The aim of the study was to compare the surgical experience, clinical outcomes, and effect on body weight between obese and morbidly obese patients undergoing lumbar spine fusion surgery. Summary of Background Data. Obese and morbidly obese patients undergoing spinal fusion surgery are a challenge to the operating surgeon. Only few reports are available on the perioperative data in this group of patients. Further, it is unknown if the degree of obesity has an effect on the surgical experience and clinical outcomes including body weight. Methods. A retrospective study of 63 patients undergoing lumbar spinal fusion was carried out. The main inclusion criteria were a body mass index (BMI) equal to or greater than 30. Information recorded included surgical set-up time, surgical time, blood loss, American Association of Anesthesiologists score, and surgical complications. At follow-up, the Oswestry Disability Index and visual analog scale for back and leg pain were recorded along with a pain diagram and radiographic evaluation. Results. The obese group had lower American Association of Anesthesiologists scores. The surgical time was dependent on the number of levels fused and was independent of the BMI. Blood loss during surgery was marginally greater in the obese patients. Neither group showed significant change in weight and BMI. Clinical outcomes showed improvement in visual analog scale for back and leg pain with some improvement in Oswestry scores and were independent of the BMI of the patient. The incidence of postoperative complications was significant in 45% of morbidly obese and 44% of obese patients. Conclusion. Obese and morbidly obese patients have multiple comorbidities, and the spinal surgeon should be prepared to encounter perioperative complexities. Operative times are longer in comparison with normal weight patients with a higher incidence of postoperative complications. No weight loss occurs after spinal surgery.

Treatment of unstable pelvic ring injuries with an internal anterior fixator and posterior fixation: initial clinical series.

Objectives: To present a novel internal fixation device for stabilizing unstable pelvic fractures using supra-acetabular spinal pedicle screws and a subcutaneous connecting rod (INFIX). Setting: Level I trauma center. Design: Case series. Patients: Twenty-four patients with rotational or vertically unstable pelvic fractures that reported to a level I trauma center. Methods/intervention: Surgical treatment of unstable pelvic fractures included reduction, appropriate posterior fixation where indicated, and an anterior subcutaneous internal fixator. Main Outcome Measurement: Healing time, quality and loss of reduction, ease of nursing, incidence of complications, including nonunion, infection, and patient mobility and comfort. Results: In the present clinical series, all fractures healed without significant loss of reduction. There were no infections, delayed unions or nonunions. Nursing care was observed to be easier especially in the intensive care unit setting. Complications included unilateral anterior thigh paresthesias in 2 patients, and 1 patient each required repositioning of the pedicle screw and readjustment of screw rod junction. Patients tolerated the procedure well and were fairly mobile after the procedure. Conclusions: The reported technique allows for a definitive and stable anterior fixation of vertically and rotationally unstable pelvic fractures when combined with the appropriate posterior fixation if indicated. The potential complications are acceptable with this technique and good outcomes were achieved. A second operative procedure is required for removal of the device. It is our view that its best indication is in obese individuals, in whom other options have shortcomings.

Surgical treatment of complete acromioclavicular dislocation using the coracoacromial ligament and coracoclavicular fixation: report of a technique in 14 patients.

Summary: Fourteen cases of a complete dislocation of the acromioclavicular joint were treated using a modified technique of surgical repair involving the transfer of the coracoacromial ligament to reconstruct the coracoclavicular ligaments and coracoclavicular fixation with a screw. In addition, the lateral 2 cm of the clavicle was removed and the coracoacromial ligament attached to the raw surface. Eleven patients underwent surgery <2 weeks after injury, whereas three underwent surgery 6 months after the initial episode. Follow-up of 2-4 years showed excellent results in 12 and good in two cases. It is our recommendation that coracoclavicular ligament reconstruction should be supplemented with clavicular fixation to the coracoid to ensure acromioclavicular alignment.

Radiographic and CT Evaluation of Recombinant Human Bone Morphogenetic Protein-2–Assisted Spinal Interbody Fusion

OBJECTIVE Bone morphogenetic proteins BMPs, when used in spinal fusion, hasten healing and initiate distinct imaging features. We undertook a study to record and analyze the radiographic and CT changes after the use of recombinant human bone morphogenetic protein-2 (rhBMP-2) in spinal fusion surgery. MATERIALS AND METHODS This study included 95 patients who underwent spinal interbody fusion using rhBMP-2. The lumbar spine fusion cohort consisted of 23 patients who underwent anterior lumbar interbody fusion, 36 patients who underwent transforaminal lumbar interbody fusion, and two patients who underwent posterior lumbar interbody fusion. The remaining 34 patients underwent anterior cervical decompression and fusion. RESULTS A polyetheretherketone cage was used as an interbody spacer in 59 patients (82 levels) and an allograft bone was the spacer in 36 patients (55 levels). Patients were evaluated 2 and 6 weeks after the procedure and then 3, 6, 12, and 24 months after the procedure. All patients underwent radiography at every follow-up visit, and CT evaluation was performed in 32 patients. CONCLUSION Features observed on imaging that we attributed to the use of rhBMP-2 included an enhanced fusion rate and an increased incidence of prevertebral soft-tissue swelling in patients who underwent cervical fusion. Endplate resorption was observed in 100% of patients who underwent cervical fusion and in 82% of the lumbar levels. Subsidence of the cage resulting in narrowing of the disk space was seen in more than 50% of cases. Cage migration and heterotopic bone formation in the spinal canal and neural foramen occurred maximally in the lumbar spine of patients in whom a polyetheretherketone cage was placed using a transforaminal approach.

Hip Dislocation After Modular Unipolar Hemiarthroplasty

An institutional review board-approved retrospective review of hip fractures in elderly patients treated with a modular unipolar implant was carried out to identify factors predisposing to dislocation of a hemiarthroplasty. The main outcome measure evaluated was dislocation vs nondislocation. Two hundred seventeen patients underwent the surgery, and 174 were available for review at 6 weeks and 144 at 1 year. The incidence of dislocation was 6%. The average time of dislocation after surgery was 19.3 days. Clinical factors significant for dislocation were male sex and mental disease. Radiographic factors in dislocated hips included a smaller femoral neck and contralateral femoral neck offset. The center edge angle was also smaller in the dislocated patients. These patients had a higher mortality rate.

Unusual spinal manifestation in secondary hyperparathyroidism: a case report.

Study Design. Case report. Objectives. To describe an unusual spinal manifestation of secondary hyperparathyroidism in a 29-year-old woman and discuss the pathologic basis of the disease and evaluate the response to treatment. Summary of Background Data. Extraskeletal tumoral calcification (i.e., tumoral calcinosis, tumoral calcinosis-like lesion, calcifying pseudoneoplasms) is an uncommon entity associated with secondary hyperparathyroidism. Involvement of the cervical spine with this tumor causing neural compression is extremely rare. Only a few cases have been reported in literature and none with a concomitant presence of brown tumors. Methods. A 29-year-old woman presented with upper back pain with tingling and weakness in the left hand. She had been on dialysis for 5 years following renal failure. She had a partial parathyroidectomy for hyperparathyroidism a year ago. Para vertebral calcification eroding the posterior elements of C6–T2 and abutting the dura and neural foramens was seen on a CT scan. There were numerous lytic defects of the thoracic and lumbar vertebral bodies, most notable at L4, suggesting focal brown tumors. An MRI scan of the spine demonstrated a large heterogeneously hypointense lesion of the cervicothoracic spine, which remained hypointense on T2 images. A cervicothoracic decompression and spinal stabilization from the front and back was performed. A pathologic diagnosis of tumoral calcinosis-like lesion was confirmed. Result. Following surgery, the patient recovered neurologically and subsequently underwent total parathyroidectomy. Presently, her bone lesions have healed. Conclusion. Hyperparathyroidism may cause tumoral calcinosis-like lesions in the spine. An early spinal decompression followed with parathyroidectomy leads to remission of symptoms.

A biomechanical study of standard posterior pelvic ring fixation versus a posterior pedicle screw construct

OBJECTIVES The purpose of this study was to biomechanically test a percutaneous pedicle screw construct for posterior pelvic stabilisation and compare it to standard fixation modalities. METHODS Utilizing a sacral fracture and sacroiliac (SI) joint disruption model, we tested 4 constructs in single-leg stance: an S1 sacroiliac screw, S1 and S2 screws, the pedicle screw construct, and the pedicle screw construct+S1 screw. We recorded displacement at the pubic symphysis and SI joint using high-speed video. Axial stiffness was also calculated. Values were compared using a 2-way ANOVA with Bonferroni adjustment (p<0.05). RESULTS In the sacral fracture model, the stiffness was greatest for the pedicle screw+S1 construct (p<0.001). There was no significant difference between the pedicle screw construct and S1 sacroiliac screw (p=1). For the SI joint model, the S1+S2 SI screws had the largest overall load and stiffness (p<0.001). The S1 screw was significantly stronger than pedicle screw construct (p=0.001). CONCLUSIONS The pedicle screw construct biomechanically compares to currently accepted methods of fixation for sacral fractures when the fracture is uncompressible. It should not be used for SI joint disruptions as one SI or an S1+S2 are significantly stiffer and cheaper.

Civilian gunshot wounds of the hip and pelvis

Objective: To evaluate orthopaedic injuries associated with civilian hip and pelvic gunshot wounds and their required surgical interventions. Design: Retrospective chart review. Setting: Level I urban trauma center. Patients: From 1999 to 2008, there were 2808 cases of gunshot wounds that reported to our hospital. Twelve hundred thirty-five patients had an associated fracture that included 42 patients with fractures of the hip and pelvis. The average age of patients was 30.3 years (range, 19-54 years) and 40 of the 42 were male. Eighteen patients (43%) underwent emergency laparotomy for suspected visceral and vascular injuries of which seven patients had a negative laporotomy. There were 18 ilium fractures, 10 hip fractures, nine acetabular fractures, seven pubic rami fractures, six sacral fractures, three sacroiliac joint injuries, and two ischial tuberosity fractures. Intervention: Seven patients required orthopaedic surgical intervention, undergoing a total of 10 operative procedures. Results: All fractures healed and there was no incidence of pelvic ring instability requiring surgical stabilization or chronic osteomyelitis. Nonorthopaedic injuries included 15 small/large bowel perforations (36%), seven vessel lacerations (17%), and two urogenital injuries (5%) that required surgery. Associated injuries included four patients with nerve damage that recovered partially. Conclusions: Pelvic fractures from civilian gunshot wounds often require emergent surgery for vascular, visceral, and urogenital injuries. Orthopaedic intervention is indicated for intra-articular pathology such as removal of projectiles or bone fragments and reconstruction of the hip and rarely the acetabulum. Pelvic instability and complications of orthopaedic injuries are uncommon. These injuries require a multidisciplinary approach in their management.

Monoaxial Pedicle Screws Are Superior to Polyaxial Pedicle Screws and the Two Pin External Fixator for Subcutaneous Anterior Pelvic Fixation in a Biomechanical Analysis

Purpose. Comparison of monoaxial and polyaxial screws with the use of subcutaneous anterior pelvic fixation. Methods. Four different groups each having 5 constructs were tested in distraction within the elastic range. Once that was completed, 3 components were tested in torsion within the elastic range, 2 to torsional failure and 3 in distraction until failure. Results. The pedicle screw systems showed higher stiffness (4.008 ± 0.113 Nmm monoaxial, 3.638 ± 0.108 Nmm Click-x; 3.634 ± 0.147 Nmm Pangea) than the exfix system (2.882 ± 0.054 Nmm) in distraction. In failure testing, monoaxial pedicle screw system was stronger (360 N) than exfixes (160 N) and polyaxial devices which failed if distracted greater than 4 cm (157 N Click-x or 138 N Pangea). The exfix had higher peak torque and torsional stiffness than all pedicle systems. In torsion, the yield strengths were the same for all constructs. Conclusion. The infix device constructed with polyaxial or monoaxial pedicle screws is stiffer than the 2 pin external fixator in distraction testing. In extreme cases, the use of reinforcement or monoaxial systems which do not fail even at 360 N is a better option. In torsional testing, the 2 pin external fixator is stiffer than the pedicle screw systems.