Plain Radiographic Views Research Articles

P162. Computed Tomography and Radiographic Assessment of Axial Plane Rotation Deformity in Scoliosis

BACKGROUND CONTEXT: Computed Tomography (CT) is a gold standard method for assessing vertebral rotation, though cost and radiation limit the usability of CT in routine assessment. Additionally, direct intraoperative assessment of rotation for pedicle screw insertion must be done via fluoroscopy or radiography. Accurate assessment of axial rotation is critical, especially for pedicle screw spine instrumentation in scoliosis. A reproducible correlation between plain radiographic views and direct angular measurement allows for easier assessment of rotation both preoperatively and intraoperatively.

Femoral perforation complicated by pedestal formation in revision hip arthroplasty

We present a case report of a patient in whom intra-operative penetration of the femoral cortex occurred during revision hip surgery. We report this to highlight that femoral perforation can occur at the pedestal while reaming the femoral canal during revision arthroplasty. Distal pedestal, the thick endosteal bone bridge at the tip of the previous stem is often difficult to ream during revision and forcible reaming may perforate the femur. Adequate two view plain radiographs should be taken intra-operatively and the use of guide wires with flexible reamers is advised to avoid perforation.

The cochlear implant electrode–pitch function

The cochlear frequency-place function in normal hearing ears has been found to be an exponential relationship in a wide variety of species [D.D. Greenwood, J. Acoust. Soc. Am. 87 (1990) 2592-2605]. Although it seems reasonable to assume a similar function for electrical stimulation by means of an intra-cochlear electrode array, the exact frequency-place function for this special type of stimulation needs to be investigated. Six users of the MED-EL COMBI 40+ cochlear implant device with moderate to profound hearing loss between 125 and 1000 Hz in the non-implanted ear took part in a binaural pitch adjustment experiment. The COMBI 40+ electrode array provides a deep insertion into the scala tympani and a wide spatial separation between the stimulating electrodes. Insertion depth was controlled by Stenver's view plain radiographs and the insertion angle was estimated. The task of the subjects was to adjust the frequency of a sinusoid presented in the non-implanted ear by means of an adjusting knob until they perceived the same pitch as was elicited by a reference stimulus in the implanted ear. The results show adjustments corresponding to electrode positions along the cochlea, with the exception of the two most apical electrodes for most of the subjects. Pitch increased in an orderly fashion with an average of 98 Hz per electrode separation (40 Hz/mm). In contrast to the exponential predictions according to [D.D. Greenwood, J. Acoust. Soc. Am. 87 (1990) 2592-2605] for normal hearing, the average electrode-pitch function shows a linear relationship.

The hamate facet of the lunate: a radiographic study in an Arab population from Bahrain

Based on the presence of a facet for the hamate two types of lunate bone have been described in the wrist; type I is without a facet for the hamate while type II bears a facet on the medial surface for articulation with the proximal pole of the hamate. Compared to type I lunates, type II lunates have been shown to have different kinematics, are more prone to clinically relevant degenerative changes in the hamato-lunate joint and may cause ulnar-sided wrist pain. The incidence of type II lunates seems to vary in different populations. Postero-anterior (PA) view of plain radiographs of the hand was studied in Arab subjects from Bahrain (n=381; 307 males and 74 females) to determine the incidence of type I and type II lunates. The mean age of the subjects was 31.1 years, the range being 18-80 years. In the population studied, only 148 (38.8%) of the 381 wrists showed type II lunate; 121 (31.7%) were found in males and 27 (7.1%) in females. There was no significant difference in the mean age of subjects with type I or type II lunates (P=0.16). There was no correlation between side and gender with the presence or absence of a hamate facet on the lunate. The incidence of type II lunate was much lower than reports in the literature of populations from the Western world, which could be attributed to a genetic variation in the Arab population in Bahrain. These data indicate that osteoarthritis of the hamate or lunate is less likely to be a cause of ulnar-sided wrist pain in Bahraini Arabs.

Radiographic Evaluation of Screw Position in Revision Total Hip Arthroplasty

Injury to intrapelvic structures during removal of screws in revision acetabular arthroplasty is an uncommon, yet potentially serious complication. Bicortical screws are at greatest risk for causing injury during removal, especially if directed toward intrapelvic vessels and nerves. Complications can be minimized with thorough evaluation of screw position before revision surgery. A study of seven cadaveric pelves was done to determine if plain radiographic views provide useful information regarding screw position. In each pelvis, bicortical transacetabular screws were fixed in all acetabular quadrants 15 mm longer than the measured depth. Afterward, anteroposterior, inlet, Judet, and cross-table lateral radiographic views were obtained and intrapelvic dissections were done. Radiographs and intrapelvic dissections were compared to determine screw position. We found that the obturator and iliac oblique (Judet) views were most useful in defining screw position. The iliac oblique view clearly revealed screws that violated the quadrilateral surface and therefore were directed toward the obturator vessels and nerve. The obturator oblique view revealed screws that violated the anterior column and therefore were directed toward the external iliac vessels. The lateral view additionally clarified such screws by determining general anterior or posterior direction.

Midline sagittal sacral fractures in anterior-posterior compression pelvic ring injuries.

To evaluate the outcome of an uncommon variant of the anterior-posterior compression pelvic injury, in which the posterior ring injury is a midline sagittal sacral fracture extending into the spinal canal. Prospective, consecutive series. SETTING Two regional trauma centers. A consecutive series of 10 patients with rotationally displaced, vertically stable anterior-posterior compression pelvic ring fractures (OTA type 61-B1) in which the posterior ring injury is a midline sagittally oriented sacral fracture involving the spinal canal (Denis zone III). This injury pattern comprised 0.6% of pelvic fractures and 1.4% of sacral fractures treated at these two institutions during a 10-year period. Patients were treated according to the same principles used in more commonly seen types of anterior-posterior compression pelvic ring injuries. Nine patients were treated with reduction and anterior pelvic stabilization at an average of 5 days after injury, 8 of whom were treated with open reduction and internal fixation and 1 with external fixation. No posterior pelvic fixation was used. One patient with nondisplaced bilateral pubic ramus fractures was treated nonoperatively. Immediate weight bearing was allowed as tolerated. Prospectively collected clinical follow-up data emphasized a detailed neurologic examination, whereas radiographic evaluation involved anteroposterior, inlet, and outlet plain radiographic views of the pelvis. An anatomical or near-anatomical reduction of the pelvis was achieved and maintained in all patients. Fractures healed at an average of 10 weeks. At an average follow-up of 31 months (range 20-46 months), there were no objective neurologic deficits that could be attributed to sacral root injury and no significant residual pain or gait disturbance related to the pelvic fracture. Loss of bowel or bladder function, loss of perianal sensation or sphincter tone, and lumbosacral radicular pain or sensorimotor deficit were specifically absent in all patients. Three patients, however, complained of sexual dysfunction at final follow-up. None of these patients had clinical evidence of sacral root/plexus injury secondary to the fracture. One additional patient, who sustained a urethral tear, required a chronic suprapubic catheter because of stricture. Six patients, one of whom had needed repair of a retroperitoneal bladder tear, had no urogenital sequelae. Patients who sustain sagittally oriented midline fractures of the sacrum that extend into the spinal canal (Denis zone III) as part of displaced, vertically stable anterior-posterior compression pelvic injuries, have a low incidence of neurologic deficit attributable to sacral root or plexus injury. This is in contrast to the high rate of neurologic deficit (>50%) otherwise reported in zone III sacral fractures, particularly in those associated with a displaced transverse component. In the midline sagittal fracture variant, simultaneous lateral displacement of both bony and neural elements through the midline may protect the sacral roots and plexi from significant traction or shear injury by maintaining the spatial orientation between the sacral foramina and sciatic notch. Long-term sequelae were related to urogenital complaints rather than to musculoskeletal problems, as 4 of the 10 patients in this series had either sexual or urologic dysfunction.

Arthroscopic treatment of symptomatic shoulders with minimally displaced greater tuberosity fracture

Purpose: The purpose of this study is to describe arthroscopic findings and the results of arthroscopic treatment of patients with chronic shoulder pain caused by a minimally displaced fracture of the greater tuberosity. Type of Study: This is a retrospective case series in a consecutive sample of 23 patients with a minimally displaced or nondisplaced fracture of the greater tuberosity who underwent outcome analysis after arthroscopic treatment. Materials and Methods: Twenty-three patients with chronic shoulder pain beyond 6 months after fracture of the greater tuberosity underwent arthroscopic treatment and were retrospectively assessed after an average of 29 months (range, 22 to 40 months). There were 18 men and 5 women with the average age of 39 years (range, 24 to 61 years). Fourteen fractures were isolated and 9 were related to acute anterior instability episode. The average displacement of the fracture was 2.3 mm (range, 0 to 4 mm) as shown on anteroposterior view plain radiographs. Results: At the time of arthroscopy, all patients had partial-thickness rotator cuff tears on the articular surface. The cuff tears were located on the tuberosity fracture area and were an Ellman grade I to II in depth. After arthroscopic debridement or repair of the tear, depending on the condition of the tear itself, as well as subacromial decompression, the UCLA score results were good to excellent in 20 and fair in 3 patients. Nineteen of the patients had returned to the previous level of activities. However, the patients engaged in overhead sports activity had a lower level of return to activity (P =.034). Conclusions: A partial-thickness rotator cuff tear on the articular surface should be considered in patients with chronic shoulder pain after a minimally displaced fracture of the greater tuberosity. Arthroscopic debridement or repair is an appropriate procedure.Arthroscopy: The Journal of Arthroscopic and Related surgery, Vol 16, No 7 (October), 2000: pp 695–700

Assessment of Stability in Children's Minimally Displaced Lateral Humeral Condyle Fracture by Magnetic Resonance Imaging

We studied 12 children who had minimally displaced lateral humeral condyle fractures. Bony gaps at the fracture site were <2 mm on the anteroposterior view of plain radiographs. To determine the stability of the fractures, we used a magnetic resonance imaging (MRI) study of the distal humerus and elbow joint. In the results, two types of fractures were classified by the extent of the fracture line in MRI. Type I showed that the line coursed from the lateral metaphysis to the growth plate but not through it. In type II, the line crossed the growth plate to enter the joint space. We concluded that the MRI study distinguished the potentially unstable fracture (type II) from the minimally displaced fracture and recommend the use of a percutaneous pin fixation for the expected unstable fracture.

Geometric variables and bone mineral density as potential predictors for mechanical properties of the radius of Greyhounds

Abstract Objective To determine cross-sectional geometry and bone mineral density of the Greyhound radius and correlate these values with torsional failure load and torsional stiffness in an ex vivo model. Design 3 regions, proximal, middle, and distal portions of the diaphysis, were studied. 5 levels of cross section were evaluated geometrically within each region. Specimens 10 paired radiuses from skeletally mature Greyhounds. Procedure Cortical area and area moment of inertia were measured from plain radiographic views and from digitized computed tomographic images. Bone mineral density was measured, using dual-energy x-ray absorptiometry. Torsional stiffness and torsional failure load were then determined mechanically. Results Minimum area moment of inertia and area moment of inertia estimated from plain radiographic views were significantly different in different regions of interest (P &lt; 0.05). Significant bivariate correlations (P &lt; 0.05) between torsional mechanical parameters and bone properties of the radius were identified for the distal portion of the diaphysis in particular. When independent variables for the distal portion were analyzed, estimate of area moment of inertia was entered into the model for torsional failure load as a predictor and minimum area moment of inertia was entered into the model for torsional stiffness as a predictor. Bone mineral density of the distal portion of the diaphysis was not a significant predictor. Conclusion If accurate noninvasive predictors of bone failure load can be identified, further study of fracture risk should be possible. (Am J Vet Res 1996;57:1094–1097)

Acetabular fractures: optimal imaging.

In 19 cases of acetabular fracture, computed tomography (CT) with volumetric three-dimensional (3D) reconstructions displayed as video loops about horizontal and vertical axes of rotation replaced the traditional imaging combination of CT and multiple plain radiographs, while offering significant advantages. Overlying bowel content or foreign matter obscured detail in 36 of 45 plain radiographic views, and positioning or radiographic technique was suboptimal in 21. Three-dimensional reconstructions completely eliminated these problems. These 3D reconstructions accurately simulated oblique, inlet, and tangential views in all cases. In ten of 19 cases a nonconventional oblique view, and in 13 of 19 cases a cephalocaudal angulation other than the inlet, tangential, or anteroposterior view, best demonstrated the fracture. Elimination of five plain radiographs resulted in a skin radiation dose savings of 5 rad (50 mGy). No difficult or painful patient positioning was required beyond that necessary for the standard CT examination.