Accuracy of pedicle screw placement: a systematic review of prospective in vivo studies comparing free hand, fluoroscopy guidance and navigation techniques.

INTRODUCTION: With the advances and improvement of computer-assisted surgery devices, computer-guided pedicle screws insertion has been applied to the lumbar, thoracic and cervical spine. The purpose of the present study was to perform a systematic review of all available prospective evidence regarding pedicle screw insertion techniques in the thoracic and lumbar human spine. MATERIALS AND METHODS: We considered all prospective in vivo clinical studies in the English literature that assessed the results of different pedicle screw placement techniques (free-hand technique, fluoroscopy guided, computed tomography (CT)-based navigation, fluoro-based navigation). MEDLINE, OVID, and Springer databases were used for the literature search covering the period from January 1950 until May 2010. RESULTS: 26 prospective clinical studies were eventually included in the analysis. These studies included in total 1,105 patients in which 6,617 screws were inserted. In the studies using free-hand technique, the percentage of the screws fully contained in the pedicle ranged from 69 to 94%, with the aid of fluoroscopy from 28 to 85%, using CT navigation from 89 to 100% and using fluoroscopy-based navigation from 81 to 92%. The screws positioned with free-hand technique tended to perforate the cortex medially, whereas the screws placed with CT navigation guidance seemed to perforate more often laterally. CONCLUSIONS: In conclusion, navigation does indeed exhibit higher accuracy and increased safety in pedicle screw placement than free-hand technique and use of fluoroscopy.

Patterns of stress distribution at the proximal femur after implantation of a modular neck prosthesis. A biomechanical study.

BACKGROUND: Modular total hip arthroplasty incorporating a double taper design is an evolution offering potential advantages compared to single head-neck taper or monolithic designs. Changes in femoral offset, neck length or femoral anteversion are expected to alter the strain distribution. METHODS: We therefore analyzed the strain patterns after usage of all types of necks of a modular neck prosthesis, implanted in composite femurs. FINDINGS: The load distribution presented a repeatable pattern. Anteverted neck combinations resulted in higher stress at the anterior surface, whereas the retroverted ones at the posterior (e.g. at the middle frontal site, stress is 13.63% higher when we shifted from the long neutral neck to the long 15° anteverted neck and at the middle back site 19.73% higher when we shifted from the long neutral to the long 15° retroverted neck). Compressive stress was larger at the calcar region and exacerbated by the use of the varus neck (e.g. at the frontal 1 site stress increased by 44.01% when we used the long 8° varus neck in comparison to the long neutral neck). Anteverted neck combinations resulted in higher strain at the anterior cortex around the tip of the prosthesis. Short necks exhibited lower stress at the femoral shaft and higher at the trans-trochanteric area. INTERPRETATION: Anteverted neck combinations could be more prone to anterior thigh pain. Because of the possible risk of adaptive hypertrophy and early mechanical failure due to increased stress, the surgeon should be cautious when using necks with combined characteristics or short necks.

Diagnostic and treatment modalities in nonunions of the femoral shaft: a review.

Nonunions of the femoral shaft represent a treatment challenge for the orthopaedic surgeon and a serious socioeconomic problem for the patient. Inadequate fracture stability, insufficient blood supply, bone loss or presence of infection are the main reasons for the development of a nonunion. Careful classification and exclusion of infection are crucial for the choice of the proper treatment alternative. Nail dynamization, primary intramedullary nailing or nail exchange, plate osteosynthesis and external fixation along with bone grafting, usage of bone substitutes and electrical stimulation can stimulate osseous union. A review of the aetiology, classification and treatment should prove helpful managing this serious complication.

Bacterial wound contamination during simple and complex spinal procedures. A prospective clinical study.

BACKGROUND CONTEXT: Spinal procedures have a potential of intraoperative contamination. C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) have been used to diagnose postoperative infections after spinal surgery. However, it has not been demonstrated if there is an association between surgical site contamination and clinical manifestation of postoperative infection based on inflammatory markers and patients' clinical course. PURPOSE: The purpose of this prospective study was to evaluate the association between surgical site contamination and the development of a postoperative infection in simple and complex surgical procedures. C-reactive protein and ESR levels were observed. The correlation between their values, surgical time, type of surgical procedures, and contaminated surgical sites was investigated. STUDY DESIGN: Prospective clinical study. PATIENT SAMPLE: The study consisted of 40 patients divided into two groups. Group A included 20 patients (mean age, 46.2 years; 12 women and 8 men) who underwent an open discectomy for a lumbar herniated disc. Group B consisted of 20 patients (mean age, 67.9 years; 11 women and 9 men) who underwent a decompression and instrumented fusion for lumbar spinal stenosis. They were followed up for an average of 26.7 months (range, 11-40 months). OUTCOME MEASURES: Samples were obtained for cultures in standard time intervals during surgery. The types of bacteria cultured were evaluated, and CRP and ESR levels were measured. METHODS: Simple lumbar discectomy (Group A, 20 patients) and instrumented lumbar decompression for degenerative lumbar stenosis (Group B, 20 patients) were performed in a prospective consecutive series of patients. All patients were operated by the same surgeon in the same operating room. Surgical site preparation in each patient was done by a standard manner. Samples were obtained for cultures in standard time intervals during surgery. C-reactive protein and ESR levels were measured preoperatively on the 3rd, 7th, and 21st postoperative days, and the clinical course of each patient was recorded. RESULTS: From 40 patients, three patients in Group A and five patients in Group B, a total of eight patients (20%) had positive cultures for bacteria. There was no statistical significance between contamination and duration of surgery in both groups. None of the patients with positive intraoperative cultures developed any clinical signs of superficial or deep postoperative spinal infection, and no additional antibiotic treatment was administered. Three patients with negative cultures developed a postoperative infection. There were no differences in CRP and ESR values between patients with contamination and noncontamination in both groups. C-reactive protein and ESR levels were significantly elevated in complex procedures (Group B) than in simple procedures (Group A). Statistical analysis of CRP and ESR values in both groups and types of bacteria cultured intraoperatively are presented. CONCLUSIONS: The results of this study demonstrate that intraoperative contamination can occur during simple and complex spinal procedures. In the absence of postoperative signs of infection in patients with intraoperative contamination, there is no need of continuing antibiotic treatment. Postoperative kinetics of CRP and ESR showed to be the same in patients with and without intraoperative contamination. Higher levels of inflammatory markers were noted in complex spinal procedures where instrumentation was applied.

Misdiagnosed bilateral C5-C6 dislocation causing cervical spine instability: a case report.

INTRODUCTION: The diagnosis of cervical spine injuries remains a significant problem in many blunt trauma patients. Correct and early diagnosis of these injuries is imperative as delayed or missed diagnoses result in increased morbidity and mortality. CASE PRESENTATION: A 57-year-old Caucasian woman presented with a misdiagnosed bilateral C5-C6 dislocation one month after a fall and head injury, without clearance of the cervical spine in her previous visits to two physicians and having already started physiotherapy sessions, despite the presence of pain in the clinical examination. Dislocation was treated with open reduction and spinal fusion with posterior instrumentation 4 weeks post-trauma. CONCLUSIONS: Every physician should be highly suspicious of cervical spine injury in blunt trauma patients with positive clinical examination and include radiologic studies in his screening modality. Physiotherapy sessions should under no circumstances be started in the presence of underlying spine injury.