Diagnostic and therapeutic features of facet and sacroiliac joint injection. Anatomy, pathophysiology, and technique.

A diagnosis of exclusion facet syndrome is considered one of the many genuine causes of low back pain. Using careful patient selection, percutaneous facet joint block is a useful diagnostic and therapeutic procedure in the management of lumbar facet syndrome. Sacroiliac joint syndrome appears to be a more tangible entity diagnostically and more amenable to injection. This article addresses the anatomy, pathophysiology, and salient radiographic features of the apophyseal joint, and describes the procedures and techniques for facet as well as sacroiliac joint injection.

Accuracy of MRI patterns in evaluating anterior cruciate ligament tears.

The purpose of this study was to determine the different patterns of anterior cruciate ligament (ACL) tears on MRI and the prevalence and accuracy of these patterns. Images were obtained on high-tesla and low-tesla units and the results compared to determine whether field strength affects the interpretation using the grading system. In 172 patients who underwent knee MRI (109 knees with high-tesla units and 63 knees with low-tesla units) and arthroscopy, there was a total of 91 arthroscopically proven ACL tears. Five patterns of ACL tears were observed and designated as type 1 (diffuse increase in signal on T2-weighted images and enlargement of the ligament, 48%); type 2 (horizontally oriented ACL, 21%); type 3 (nonvisualization of the ACL, 18%); type 4 (discontinuity of the ACL, 11%); and type 5 (vertically oriented ACL, 2%). The positive predictive value (PPV) for type 2, 4, and 5 patterns was 100% for both field strengths: for type 3 PPV was just above 80% for both field strengths. The PPV value for type 1 was 90% for the high-tesla unit and 79% for the low-tesla, unit, which was not statistically significant. Combining the results of both field strengths, the overall sensitivity and specificity were 93% and 89%, respectively. Arthroscopic results were also used to determine the association between meniscal and ACL tears. Only 13% of ACL tears were isolated, the rest being associated with meniscal tears. Forty-five percent of medial meniscal and 50% of lateral meniscal tears were associated with an ACL tear, and 94% of ACLs were torn when both menisci were torn.

Effects of functional electrical stimulation on the joints of adolescents with spinal cord injury.

Nineteen adolescent subjects with complete spinal cord injuries resulting in paraplegia or tetraplegia participated in a functional electrical stimulation (FES) program consisting of computerized, controlled exercise and/or weight bearing. The effects of stimulated exercise and standing/walking on the lower extremity joints were prospectively studied. Plain radiographs and MRIs were obtained prior to and following completion of the exercise and standing and walking stages. In addition, the joints of five subjects were studied with synovial biopsies, arthroscopy, and the analysis of serum and synovial fluid for a 550 000 dalton cartilage matrix glycoprotein (CMGP). Pre-exercise joint abnormalities secondary to the spinal cord injury improved following the stimulation program. None of the subjects developed Charcot joint changes. Upon standing with FES, one subject with poor hip coverage prior to participation developed hip subluxation which required surgical repair. No other detrimental clinical effects occurred in the lower extremity joints of subjects participating in an FES program over a 1-year period.

Carpal tunnel syndrome. MR imaging diagnosis.

Carpal tunnel syndrome is a common condition that is often diagnosed by careful history and physical examination. Symptoms from cervical disc disease, thoracic outlet syndrome, and more proximal entrapment syndromes of the median nerve may be confused clinically with carpal tunnel syndrome. Incision of the flexor retinaculum in these patients will not relieve the symptoms, because the locus of the entrapment is not in the carpal tunnel. Electrophysiologic studies are invasive, painful, and may be equivocal on occasion. Furthermore, they provide little information into the cause of carpal tunnel syndrome. MR imaging is the best modality to image the carpal tunnel. It can define the locus of entrapment to the carpal tunnel. Findings includes swelling of the median nerve just proximal to the carpal tunnel, flattening of the nerve within the carpal tunnel, bowing of the flexor retinaculum, and increased signal intensity of the median nerve. Etiologic findings can differentiate space occupying lesions from diffuse inflammatory causes, and this may aid in management. Also, the signal characteristics of soft-tissue masses may be diagnostic. Knowledge of the course of the median nerve may be helpful when planning corticosteroid injection or surgery, especially with the endoscopic technique. MR imaging also may serve a role in postoperative evaluation of patients with recurrent symptoms by demonstrating an incomplete release of the flexor retinaculum or healing of an incised retinaculum. These unique abilities of MR imaging makes it a useful diagnostic tool not only for the initial evaluation and management but also in the postoperative evaluation of patients with carpal tunnel syndrome.

The semimembranosus-tibial collateral ligament bursa. Anatomical study and magnetic resonance imaging.

A bursa that was deep to the tibial collateral ligament and adjacent to the semimembranosus tendon was studied in fifty cadaveric knees; a vinyl solution was injected into four of the specimens in order to facilitate a study of the relationship between the bursa and its surrounding structures. The bursa had the shape of an inverted U: the superficial arm was an elliptical pocket that was located between the semimembranosus tendon and the tibial collateral ligament, and the deep arm was a triangular pocket that was located between the semimembranosus tendon and the medial tibial condyle. The bursa measured, on the average, twenty-one millimeters in its greatest anteroposterior dimension and ten millimeters in its greatest superoinferior dimension. Magnetic resonance images were made of two patients, and they showed fluid in the bursa.

Efficacy of limited CT for nonvisualized lower cervical spine in patients with blunt trauma.

Records of 100 patients with blunt injury and nonvisualization of C7 and T1 on cross-table lateral and swimmer's views were reviewed to evaluate the usefulness of limited computed tomographic (CT) scans in "clearing" the lower cervical vertebrae of injury. CT was deemed necessary and performed in all of these cases because the lower cervical spine could not be evaluated clinically or with plain radiographs. Ninety-seven of these 100 patients had normal findings on CT and only three patients showed cervical spine fractures. All three had isolated and stable fractures. Two of these patients had "clay-shoveler" fractures at C6 and C7, respectively, and one had a single laminar fracture at C7. All three patients were conservatively treated. This study emphasizes the value of clinical correlation in the evaluation of cervical spine trauma. When deemed necessary in symptomatic patients, CT is useful to exclude skeletal injury in the lower cervical spine thus avoiding delay in the patient's workup and unnecessary hospitalization, and expediting patient discharge. Lack of pain and neurological findings in nonintoxicated, conscious, and alert patients is generally not associated with significant soft tissue or skeletal injury.

Magnetic resonance imaging of ankle ligaments. Emphasis on anatomy and injuries to lateral collateral ligaments.

Ankle ligament sprains are the most frequent sports injury, and radiographic evaluation of the ankle accounts for 10% or all radiographic examinations requested from an emergency department. This article reviews the diagnosis of the ankle sprain and the anatomy and injuries of the ankle ligaments.

MR imaging of the knee: expanded classification and pitfalls to interpretation of meniscal tears.

Findings from magnetic resonance (MR) imaging examinations of 194 knees were interpreted retrospectively with a new classification, including not only signal intensity but morphologic abnormalities. All findings were correlated with prospectively recorded results from arthroscopic examinations performed by a knee subspecialist. Meniscal MR imaging findings were expanded to eight types in this study. Positive predictive values for each type of finding and overall accuracy were calculated. Several potential sources of error that could be differentiated through pathologic change were recognized. Sensitivity and specificity of MR imaging findings were, respectively, 95% and 74% for the medial meniscus and 86% and 90% for the lateral meniscus. As the classification grade increased, the likelihood of meniscal tear also increased. Medial meniscal tears tended to occur in a predictable pattern, extending from the posterior to the anterior horn. Thus, when a definite tear of the body or anterior horn of the medial meniscus is present, a tear of the posterior horn should be suspected, even if the findings are not convincing. This expanded classification may be useful for radiologists in expressing their level of confidence in a particular MR imaging finding suggestive of meniscal injury.

MR imaging of the most commonly injured ankle ligaments. Part I. Normal anatomy.

To determine the optimum foot position and imaging plane at magnetic resonance (MR) imaging of each ankle ligament, 10 cadaver ankles were dissected to visualize the orientation, precise attachment sites, and relationships of each ligament. Then eight cadaver ankles were studied with MR imaging and were cryosectioned in the optimum imaging planes. The ankles of 12 healthy volunteers were imaged to ensure consistency in identifying the normal ligaments. With the foot taped into full dorsiflexion of 10 degrees-20 degrees, axial imaging provided optimum views of the anterior, posterior, and inferior tibiofibular ligaments and of the anterior and posterior fibulotalar ligaments and provided an overview of the deltoid ligament. Coronal images provided full-length views of the tibiospring, tibiocalcaneal, and posterior tibiotalar parts of the deltoid ligament. With the foot taped into full plantar flexion of 40 degrees-50 degrees, axial imaging optimized visualization of the fibulocalcaneal ligament and of the tibionavicular and anterior tibiotalar parts of the deltoid ligament. Sagittal images provided the best full-length views of the spring ligament.

MR imaging of the most commonly injured ankle ligaments. Part II. Ligament injuries.

Thirteen patients with clinically diagnosed sprained ankles underwent magnetic resonance (MR) imaging. Five of these cases are presented to illustrate the potential of MR imaging to enable identification of both primary and associated ligament injury sites, grading of the severity of the injuries, and visualization of the associated findings of tendon sheath and joint effusion. The appropriate combination of foot position and imaging plane is essential to achieve full-length visualization of each ligament. Two patients demonstrated findings compatible with total gross disruption of the anterior fibulotalar ligament; two, with injury to the fibulocalcaneal ligament with effusion of the overlying peroneus tendon sheath; and one, with thinning, lengthening, and fibrotic changes involving the anterior fibulotalar ligament. MR imaging can provide a noninvasive means to evaluate the site and severity of ankle ligament injuries (a) in acute ankle injuries that demonstrate significant instability, (b) in stable acute injuries involving athletes or litigation, or (c) in patients with repeated injuries or instability in whom surgery is contemplated.

Magnetic resonance imaging of osteomyelitis.

Early diagnosis and detection of osteomyelitis and differentiation of soft-tissue infection from bone involvement is a difficult clinical and imaging problem. Magnetic resonance imaging has proven to be as sensitive as bone scintigraphy in the early detection of osteomyelitis, and, with its superior spatial resolution, MR is often more specific than planar scintigraphy in differentiating bone from soft-tissue infection and separating arthritis, cellulitis, and soft-tissue abscess from osteomyelitis. In several comparative studies, MR has been more advantageous in detecting the presence and determining the extent of osteomyelitis over scintigraphy, CT scan, and conventional radiography. MRI may facilitate differentiation of acute from chronic osteomyelitis and may help to detect foci of active infection in the presence of chronic inflammation or posttraumatic lesions. MRI has a large role in evaluating the presence and extent of spondylitis and epidural abscess and certain distribution features may help recognize tuberculous spondylitis. Gadolinium-enhanced MR could be helpful in delineating the meninges and demonstrating the border and extent of epidural abscesses.

Post-traumatic spinal cord cysts evaluated by magnetic resonance imaging.

In order to determine a more accurate prevalence of post-traumatic spinal cord cysts (PTSCC) in spinal cord injured (SCI) patients, we retrospectively reviewed magnetic resonance scans from symptomatic imaging and asymptomatic SCI patients. We found the incidence of PTSCC to be 51% in our patient population. The only symptom that correlated to the presence of a cyst was spasticity. The cyst develops at the site of injury and appears to be a common sequela of SCI. We believe that conservative treatment is indicated in most patients with a PTSCC.

Hemodialysis-related amyloidomas of bone.

Lytic bone lesions secondary to amyloid deposition are a recently described complication of long-term hemodialysis. The authors refer to these tumorlike deposits as amyloidomas in a review of the subject and four proved cases. This entity typically appears as multiple well-defined, juxta-articular lytic lesions without matrix calcification. The duration of hemodialysis is probably the greatest risk factor for development of these intraosseous amyloidomas. Ultrastructurally, this new type of amyloid originates from beta 2-microglobulin, a low-molecular-weight serum protein that is not filtered by standard dialysis membranes.

The effect of magnetic resonance imaging on metal spine implants.

In Part 1 of this study, the forces and torques exerted on metallic spine implants by a 0.3-T magnetic field were evaluated using a cantilever system sensitive to forces as low as 250 mg and torques as low as 4 g/cm. Results indicated that the 0.3-T magnification field did not cause forces or torques that could be measured within this range. It is concluded that patients with spine implants may safely undergo magnetic resonance scanning. In Part 2, the magnetic resonance scans from 33 patients (61 studies) then were reviewed to determine which, if any, parameters could be adjusted to minimize artifact. Magnetic power, slice thickness, plane of scan, and pulse sequence were considered. Plane of scan was found to be the most significant parameter in achieving useful studies, with the sagittal plane being the preferred orientation. Scans of patients who had posterior wiring were more likely to be useful, while scans of patients with spinal rods usually showed a large amount of artifact.

Carpal tunnel: MR imaging. Part II. Carpal tunnel syndrome.

The magnetic resonance (MR) images of 14 wrists of patients with carpal tunnel syndrome (CTS) were studied. Four general findings visible regardless of the cause of CTS included swelling of the median nerve, best evaluated at the level of the pisiform bone; flattening of the median nerve, most reliably judged at the hamate level; palmar bowing of the flexor retinaculum, best visualized at the level of the hamate bone; and increased signal intensity of the median nerve on T2-weighted images. Findings related to cause were tendon sheath edema in traumatic tenosynovitis, synovial hypertrophy in rheumatoid tenosynovitis, a ganglion cyst, and excessive amount of fat within the carpal tunnel, a persistent median artery, and a large adductor pollicis muscle. Knowledge of these findings may permit more rational choice of treatment. In four cases in which symptoms persisted after surgery, findings valuable in explaining or predicting the failure included incomplete incision of the flexor retinaculum, excessive fat within the carpal tunnel, persistent neuritis of the median nerve, and development of neuromas.

Carpal tunnel: MR imaging. Part I. Normal anatomy.

To correlate the important structures of the carpal tunnel demonstrated on magnetic resonance (MR) images with gross anatomy, the authors imaged the wrists of 20 normal volunteers and nine cadavers. The cadaver specimens were sectioned in the same planes in which they were imaged, and three other specimens were dissected. The anatomy was directly correlated with the imaged morphology. Axial images delineated well the bone and ligament walls of the carpal tunnel. The median nerve was well delimited and of moderate signal intensity. It was surrounded in some cases by fat but was consistently bound by specific tendons. The ulnar nerve and artery were visualized as they traversed the Guyon canal to their division into superficial and deep branches. Coronal images permitted optimal visualization of the triangular fibrocartilage and the radial and ulnar collateral ligaments. Quantitative studies indicated that the normal median nerve does not significantly increase in size within the carpal tunnel but does become more flattened at the level of the pisiform bone. The normal flexor retinaculum may have a slight palmar bowing.

Computer tomography evaluation of Cotrel-Dubousset instrumentation in idiopathic scoliosis.

In 30 adolescent patients with 36 structural curves undergoing posterior spinal arthrodesis using Cotrel-Dubousset (CD) instrumentation, computer tomography (CT) was performed to evaluate the change in rotation and in the sagittal plane. The average preoperative Cobb angle was 51.7 degrees, and improved to 18.7 degrees postoperatively, or 64.9%. The angle of rotation of the apical vertebra relative to the anterior midline of the body (RAML) improved from 27.9 degrees preoperatively to 21.5 degrees postoperatively (23.9%). The angle of rotation relative to the sagittal plane (RAsag) improved from 15.2 degrees preoperatively to 13.4 degrees postoperatively (14.3%). The kyphotic angle increased an average of 10.6 degrees in the 14 patients whose preoperative angle was less than 25 degrees. As measured by CT, CD instrumentation improves both the rotational and sagittal plane deformities better than that reported for other systems.