Cheryl A. Petersilge

Morphologic considerations of C2 isthmus dimensions for the placement of transarticular screws.

Study Design. This study examines the C2 vertebrae using both direct anatomic and computed tomographic measurements. Objective. To define the relation of the C2 vertebrae bony elements to the vertebral artery and the spinal canal, to determine individuals at risk for vertebral artery injury during C1–C2 transarticular screw placement. Summary of Background Data. Recent literature assessing the safety of upper cervical spine transarticular screws has concentrated on technique, including the optimal point of entry and path projection of the screw. The actual dimensions of the C2 isthmus of the pars interarticularis has not been examined in a large number of specimens. Methods. C2 isthmus width and height measurements were made on 205 human cadaveric C2 vertebrae. Vertebrae predicted to be at risk for vertebral arterial injury were imaged by computed tomography. Results. There were 102 female and 103 male specimens with mean isthmus widths of 8.2 ± 1.5 mm and 7.2 ± 1.3 mm, respectively. Five specimens (2.4%) had an isthmus width less than 5 mm. The mean isthmus heights were 8.6 ± 2.0 mm and 6.9 ± 1.5 mm for male and female specimens, respectively. In twenty-four specimens (11.7%), one or both isthmi had a height of less than 5 mm. Six of these specimens were male and 18 were female. The right C2 isthmus was generally smaller than the left. Computed tomographic measurements closely approximated those of the actual dimensions of the isthmi. Conclusions. Placing a 3.5 mm screw in a patient with narrow C2 isthmus dimensions (smaller than 5 mm in either the height or width) is technically difficult. Because of narrow C2 isthmus width and/or height, approximately 10% of patients may be at risk for a vertebral artery injury with placement of C1–C2 transarticular screws.

Augmentation of spinal arthrodesis with autologous bone marrow in a rabbit Posterolateral spine fusion model

STUDY DESIGN Posterolateral spinal fusion with autologous bone marrow aspirate in addition to autograft iliac crest bone graft in a rabbit model. OBJECTIVE To demonstrate that the addition of autologous bone marrow can have positive effects on bone formation and spinal fusion. SUMMARY OF BACKGROUND DATA Bone marrow has been shown to contain osteoprogenitor cells. A number of studies have demonstrated that bone formation is possible with autologous marrow injection into orthotopic sites such as that performed in femur fracture models. METHODS A bone paucity model of posterolateral spine fusion was developed. The control animals received 0.8 g of morselized autogenous iliac crest bone graft harvested from a single iliac crest. The graft was mixed with 2 mL of clotted peripheral blood. In the experimental group, 2 mL of bone marrow aspirated from the opposite iliac crest was substituted for the peripheral blood clot. All rabbits were killed at 12 weeks, and the specimens were subjected to evaluation by posteroanterior radiography for the presence of fusion, computed tomography for bone volume, and biomechanical testing for stiffness. RESULTS Successful fusion was achieved in 61% of the animals in the experimental group versus 25% in the control group (P < 0.05). The fusion mass in the experimental group had a mean volume of 919 +/- 387 mm3 versus 667 +/- 512 mm3 for the control group, as measured from computed tomography images. The results of the biomechanical testing validated the radiographic scoring system. The stiffness in specimens, graded as having a radiographic score of 4, was significantly greater than in specimens with radiographic scores of 1 and 2. CONCLUSION In cases for which an adequate quantity of autogenous bone graft is not available, addition of bone marrow may facilitate greater bone formation and successful fusion.

Accuracy of using computed tomography to identify pedicle screw placement in cadaveric human lumbar spine

Study Design. Utility of using computed tomography to predict pedicle screw misplacement. Objective. This study defines the sensitivity and specificity of predicting pedicle screw placement by experienced clinicians using a CT scan image. Summary of Background Data. In clinical and research settings, the method most commonly used to evaluate pedicle screws placement has been computed tomography. However, no current literature describes the accuracy of this method of evaluating screw placement. Method. Cobalt‐chrome and titanium alloy pedicle screws of identical size were placed in six cadaveric human lumbar spine. Wide laminectomy was performed to allow complete visualization of the pedicles. Three consecutive lumbar levels were instrumented in each spine, giving 36 pedicle screw placements to identify. The instrumented spines were imaged, and four orthopaedic spine surgeons and a musculoskeletal radiologist were asked to read the images to identify the accuracy of screw placement within the pedicles. Results. The sensitivity rate of identifying a misplaced screw was 67 ± 6% for cobalt‐chrome screws compared with 86 ± 5% for titanium screws (P < 0.005). The specificity rates of radiographic diagnosis of misplaced pedicle screws were 66 ± 10% for cobalt‐chrome screws and 88 ± 8% for titanium screws (P < 0.005). Similarly, a statistically significant difference was found in the sensitivity rates of identifying screws placed correctly in the pedicle: 70 ± 10% for cobalt‐chrome screws versus 89 ± 8% for titanium screws (P < 0.005). Overall accuracy rates were 68 ± 7% for cobalt chrome screws versus 87 ± 3% for titanium screws (P < 0.002). Conclusion. Reliance on the computed tomography scan data alone in determining accuracy of pedicle screws can lead to inaccuracies in both clinical and research conditions.

Tibial stress fracture after a graft has been obtained from the fibula : A report of five cases

Stress fractures of the lower extremity may result from overuse of normal bone or from normal loading of structurally deficient bone. Stress fractures of the pelvis have been reported as a complication after a bone graft has been obtained from the iliac crest4. Han et al. reviewed the cases of 160 patients who had had a vascularized bone transfer. Of the 132 patients who had had a fibular transfer, one had a tibial stress fracture but no follow-up information was provided. To our knowledge, no reports have addressed only fatigue failure of the tibia after the attainment of a graft from the fibula. We report the cases of five patients who had a tibial stress fracture after a graft had been obtained from the ipsilateral fibula for use in anterior reconstruction of the spine. Patients who have persistent or recurrent pain in the leg after a graft has been obtained from the fibula should be evaluated for a possible stress fracture of the tibia. CASE 1. A sixty-eight-year-old woman who had spondylotic myelopathy had a three-level anterior cervical corpectomy with insertion of an autogenous fibular strut graft from the third to the seventh cervical vertebra. She had had an early natural menopause when she was approximately forty-one years old and had never received estrogen-replacement therapy. There was no history of smoking. A graft, six centimeters long, was obtained from the middle third of the left fibula with use of a power-driven microsagittal saw and periosteal elevators. Postoperatively, the patient was allowed to bear weight as tolerated and performed no specific exercises for the lower extremity. A cane was used for balance for approximately six weeks because of the severe myelopathy. The patient had an uneventful perioperative course and was seen at a routine follow-up examination six weeks postoperatively. …

CT-guided fine needle aspiration and needle core biopsy of skeletal lesions. Complementary diagnostic techniques

OBJECTIVE To compare the diagnostic sensitivity and specificity of fine needle aspiration (FNA) to those of needle core biopsy (NCB) and to attempt to determine if a complementary role exists for the two modalities. STUDY DESIGN Skeletal lesions in 144 patients were evaluated with concomitant FNA and NCB over a 21-year period. FNAs and NCBs were divided as diagnostic of neoplasm, normal or inflammatory (i.e., osteomyelitis), or unsatisfactory. The results of each modality were then reviewed and compared. RESULTS In the 144 total cases, a diagnosis was possible in 79% (114) cases. FNA and NCB concurred in 73% (83) of diagnostic cases. Concurrence was 87% between diagnostic FNA (83) and NCB (95). The two modalities agreed in 78% of cases diagnosed as metastatic carcinoma and in 59% of primary malignant tumors of bone (17) (excluding Ewings sarcoma). FNA alone was diagnostic in 8% (9) of cases, including 5 metastatic carcinomas, 2 chondrosarcomas, 1 Ewings sarcoma and 1 case of osteomyelitis. This represented 24% of the 38 cases in which NCB was unsatisfactory (11) or normal (27). NCB alone was diagnostic in 19% (22) of cases, including 11 metastatic carcinomas, 3 osteosarcomas, 1 chondrosarcoma, 1 spindle cell sarcoma (not otherwise specified), 1 Ewings sarcoma, 2 capillary hemangiomas and 3 cases of osteomyelitis. This represented 43% of the 51 cases in which FNA was misinterpreted (2), unsatisfactory (33) or normal (16). NCB more specifically typed a metastatic lesion or suggested a primary focus in 21% (12) of the 58 cases in agreement. It also more specifically subtyped 50% (5) of the 10 primary malignant tumors of bone. CONCLUSION Given these findings, NCB is more specific in the evaluation, grading and typing of skeletal lesions in particular malignant primary bone tumors. Overall, there is excellent agreement between FNA and NCB, especially in the evaluation of benign primary bone tumors. Most important, FNA improved the diagnostic yield in 24% of cases when NCB was normal or unsatisfactory, obviating the need for rebiopsy. FNA should be performed concurrently with NCB in the evaluation of skeletal lesions since the two modalities are complementary.

Cortical metastatic lesions of the appendicular skeleton from tumors of known primary origin.

Background and Objectives: Metastatic disease represents the most common neoplastic process involving bone. Recently, a small subset of cortical based metastatic lesions has been identified. We attempted to delineate the incidence, origin, location, and possible significance of these lesions within an orthopaedic patient population.

Association of Bladder Exstrophy With Congenital Pathology of the Hip and Lumbosacral Spine: A Long-term Follow-up Study of 13 Patients

The authors evaluated, clinically and radiographically, 13 of 28 patients with bladder exstrophy treated at their institution between 1964 and 1982. All had been treated with bilateral iliac osteotomies and pelvic rami reapproximation to assist in urologic repair. At skeletal maturity, the diastasis had partially recurred and the patients had short stature and were living normal lives. Mild acetabular dysplasia and other pelvic abnormalities were common, as were abnormal radiographic findings in the lumbosacral spine. Despite these findings, most did not affect function. These results support the need for pelvic reconstruction for urologic repair, as well as the need for periodic radiographic evaluation of the pelvis and lumbosacral spine. If present, these have the potential to adversely affect function as an adult.

Sternoclavicular joint ganglion cysts in young children.

Ganglion cysts originating from the sternoclavicular joint in children have not been previously reported. In this study, 5 children who presented with a small mass over the anterior aspect of the sternoclavicular joint were evaluated and treated. Only 1 patient was symptomatic. A ganglion cyst was suspected in each case and confirmed by magnetic resonance imaging in 3 patients and ultrasound in one patient. Excisional biopsy was performed in 3 patients and the diagnosis of a ganglion cyst confirmed histopathologically. No patient has had a recurrence. Observation of asymptomatic cystic lesions that arise in the sternoclavicular location is recommended.

The Evolution of Enterprise Imaging and the Role of the Radiologist in the New World

OBJECTIVE The concept of enterprise imaging is part of the next frontier in the evolution of health care technology. Incorporating all medical images into a single location integrated with electronic medical records supports care coordination and the ideal of a comprehensive longitudinal medical record. CONCLUSION Radiologists have tremendous value to offer in support of the new concept of enterprise imaging, which extends outside the radiology department to encompass all image producers in a health care enterprise.

Knee pain and swelling in a 30-year-old woman.

A 30-year-old woman presented to her tecedent trauma to the area, and the medical physician with a 4-month history of increashistory was noncontributory. Physical examing pain and swelling around the left knee. ination revealed mild swelling around the The pain had increased in severity until, with proximal tibia that was tender to palpation. weightbearing, it could not be tolerated withThe joint did not have an effusion and had a out crutches. There was no history of anfull range of active motion. The neurovascu-