E. Mark Levinsohn

The role of radiography and computerized tomography in the diagnosis of subluxation and dislocation of the distal radioulnar joint

The diagnosis of an isolated subluxation or dislocation of the distal radioulnar joint (DRUJ) may be extremely difficult to make from the standard radiographic examination. Radiographs and computerized tomographic (CT) scans of cadaver wrists were used to evaluate subluxation and dislocation of the DRUJ. Both subluxation and dislocation could be accurately diagnosed from a true lateral radiographic projection of the wrist with the forearm in neutral rotation. Minimal supination or pronation of the forearm led to inaccurate diagnosis. A single CT scan through the DRUJ was diagnostic for subluxation and dislocation in all positions of forearm rotation. Wrist pain, plaster immobilization, or suboptimal wrist positioning may make it impossible to obtain a perfect lateral view of the wrist, thereby precluding the radiographic diagnosis of DRUJ subluxation and dislocation. In this instance, a single CT scan through the DRUJ is recommended.

Arthrography of the wrist

Eighty-four wrist arthrograms were performed on 76 patients with posttraumatic wrist pain. Instillation of a small amount of contrast media into the radiocarpal joint under fluoroscopic control was helpful in delineating specific areas of pathology about the wrist. Comparison of the arthrographic findings with the plane films of 74 patients and the operative findings of 24 patients revealed that the arthrogram was most helpful in delineating perforations of the scapholunate ligament, the lunotriquetral ligament, the triangular fibrocartilage complex, and the wrist joint capsule.

The triple-injection wrist arthrogram

The last 100 patients to have wrist arthrography at our institution had, in addition to the standard radiocarpal joint injection, injections into the distal radioulnar joint and midcarpal joint. Seventy-seven of the 100 patients had abnormal arthrograms. In 29 cases abnormalities not identified by the radiocarpal joint injection were demonstrated either by the distal radioulnar joint or the midcarpal joint injection. In 38 patients abnormalities shown by radiocarpal joint injection were not demonstrable by the other two injections. Seven detachments of the triangular fibrocartilage complex from the ulnar styloid could be demonstrated only by the distal radioulnar joint injection. The midcarpal joint injection was far more useful than the radiocarpal joint injection in the evaluation of radiocarpal joint-midcarpal joint communications. All three injections appear to be necessary for a complete arthrographic evaluation.

Wrist arthrography: the value of the three compartment injection technique

Arthrography of the wrist was performed on 50 consecutive patients with obscure post-traumatic wrist pain by injecting contrast separately into the radiocarpal joint, midcarpal compartment, and distal radioulnar joint. When distal radioulnar joint and midcarpal compartment injections were added to the standard radiocarpal injection, many significant unsuspected abnormalities were identified. Of the 25 triangular fibrocartilage complex abnormalities identified, six (24%) were found only with the distal radioulnar joint injection. Of the 29 abnormal communications between the midcarpal compartment and the radiocarpal joint, ten (35%) were found only with the midcarpal injection. Similarly, five of 29 (17%) of the abnormal radiocarpal-midcarpal communication would have been missed if a midcarpal injection alone had been performed. These findings indicate that separate injections into the radiocarpal joint, midcarpal compartment, and distal radioulnar joint are needed to identify a large number of abnormalities not seen with injections into one compartment alone.

Magnetic resonance imaging of the triangular fibrocartilage complex

Magnetic resonance imaging of seven fresh human cadaveric specimens was used to evaluate the integrity of the triangular fibrocartilage complex of the wrist. A variety of imaging parameters were systematically investigated, including T1-weighted images with and without contrast, long repetition times, short echo time images, and T2-weighted sequences. A variety of imaging planes were also evaluated. Wrist arthrography, dissection, and frozen coronal sections were done to substantiate our interpretations of the magnetic resonance images. T2-weighted images in the coronal plane proved to be of the greatest diagnostic value because the synovial fluid of the joint spaces serves as an excellent endogenous contrast agent. Long repetition time, short echo time sequences could be simultaneously obtained with T2-weighted sequences with the use of a multi-echo pulse sequence to provide an excellent diagnostic package in the future. On the basis of our investigation, the triangular fibrocartilage complex can be consistently and accurately evaluated with magnetic resonance imaging. As magnetic resonance imaging technology improves, wrist probes and suitable magnets should become available that will make the evaluation of triangular fibrocartilage complex abnormalities with magnetic resonance imaging clinically useful.

Pulsed color-flow Doppler analysis of arterial deficiency in idiopathic clubfoot.

This prospective study used pulsed color-flow Doppler sonography to determine differences in the presence and direction of flow through the dorsalis pedis, posterior tibial, and peroneal arteries in a group of children with clubfoot and a comparison group of controls. There was a statistically significant difference in the prevalence of deficient (absent or retrograde flow) dorsalis pedis arteries in children with clubfoot (45%) compared with controls (8%). This indicates that there is an association between some clubfeet and deficiency of the dorsalis pedis artery. There was a trend toward difference in the prevalence of deficiency of the dorsalis pedis artery in the clubfeet that required surgery (54%) compared with those that did not (20%), suggesting that dorsalis pedis artery deficiency may be more prevalent among clubfeet with greater deformity.

Bicipital groove dysplasia and medial dislocation of the biceps brachii tendon

The purpose of this study was to investigate the plain film finding of dysplasia of the lesser tubercle of the humerus and its relationship to medial dislocation of the tendon of the long head of the biceps brachii muscle as diagnosed by shoulder arthrography. Of 55 patients referred for arthrography of the shoulder because of undiagnosed shoulder pain, 12 demonstrated flattening of the medial wall of the bicipital tendon groove. Of these, 58% had medial dislocation of the biceps tendon, and 43% of patients with dislocation of the biceps tendon were also shown to have a tear of the rotator cuff. Since biceps tendon pathology has long been implicated in shoulder pain and weakness, assessment of the bicipital groove may provide important information in evaluating patients with potential abnormality of the biceps tendon.The purpose of this study was to investigate the plain film finding of dysplasia of the lesser tubercle of the humerus and its relationship to medial dislocation of the tendon of the long head of the biceps brachii muscle as diagnosed by shoulder arthrography. Of 55 patients referred for arthrography of the shoulder because of undiagnosed shoulder pain, 12 demonstrated flattening of the medial wall of the bicipital tendon groove. Of these, 58% had medial dislocation of the biceps tendon, and 43% of patients with dislocation of the biceps tendon were also shown to have a tear of the rotator cuff. Since biceps tendon pathology has long been implicated in shoulder pain and weakness, assessment of the bicipital groove may provide important information in evaluating patients with potential abnormality of the biceps tendon.

Anatomy of a duplicated human foot from a limb with fibular dimelia.

At birth, a patient presented with a right lower limb featuring preaxial polydactyly and fibular dimelia with a complete absence of the tibia. Radiographic studies of the patients foot revealed a duplicated tarsus with eight metatarsals and toes. The three preaxial toes were surgically removed at 1 year of age. A hallux and four normal-appearing postaxial toes remained. The foot was amputated when the patient was 3 years old. Dissection of the amputated foot revealed that the muscles of the dorsum were normal, except that the tendon of the extensor hallucis brevis muscle inserted into both the hallux and toe 2, rather than only into the hallux. The few abnormalities observed among the muscles on the plantar surface of the foot included absence of the insertions of the tibialis posterior and the abductor hallucis muscles. In addition, the two heads of the adductor hallucis muscle inserted abnormally into the medial (tibial) side of metatarsal 1, rather than into the lateral side. These various muscular anomalies, in addition to the mirror duplication of the foot with the presence of only a single metatarsal 1, leads us to propose that this metatarsal probably represents two lateral (fibular) halves that form a laterally duplicated bone. Although the dorsalis pedis artery was present on the dorsal surface of the foot, most of its derivatives were absent. This artery did give rise to a supernumerary medial branch that ended abruptly in the connective tissue (presumably postsurgical scar) at the medial border of the foot. This branch may have represented a duplicated dorsalis pedis artery associated with the duplicated preaxial portion of the foot. The arteries on the plantar surface of the foot were normal. Even though some anomalies in the pattern of the cutaneous innervation were observed, the nerves of the foot were largely normal. The gross and radiographic anatomy of this specimen and the radiographic anatomy of the leg suggest that some teratogenic event occurred when developmental specification reached the level of the future knee. The teratogenic event, which probably occurred early in the fifth week of development, may have caused damage that led to a lateral duplication of both the leg and the foot with the absence of some of the most medial structures. Teratology 60:272-282, 1999.

The wrinkled patellar tendon: an indication of abnormality in the extensor mechanism of the knee

Rupture of the quadriceps tendon is an uncommon condition which requires early diagnosis and treatment to avert prolonged disability. In four patients who had surgically confirmed quadriceps tendon rupture, lateral radiographs of the knee and/or sagittal magnetic resonance (MR) images demonstrated a corrugated appearance to the patellar tendon. Sagittal MR images of the knee following patellectomy in one patient and radiographs of a transverse fracture of the patella in another also demonstrated this appearance. MRI has superb contrast resolution which provides optimal visualization of the contour of the patellar tendon on sagittal images. A retrospective review of 50 consecutive knee MRI examinations was carried out to evaluate the appearance of the normal patellar tendon. In 49 of 50 patients, the sagittal images demonstrated a straight or nearly straight patellar tendon. A corrugated appearance of the patellar tendon on sagittal images indicates a reduction in the normal tensile force applied to it and indicates the need for careful evaluation of the patella and quadriceps tendon mechanism.

An unusual presentation of a ring injury

A case of chronic erosion of the soft tissues and bone of the proximal phalanx of the ring finger in a 62-year-old woman is presented. The patients rings had eroded the skin, nerves, and tendons of the finger as well as the palmar aspect of the proximal phalanx; however, circulation was adequate. When the rings were removed, there was no improvement in sensibility or range of motion, but this was not bothersome to the patient.