Growth and development of the pediatric cervical spine documented radiographically.

BACKGROUND: The radiographic anatomy of the cervical spine in children is complex and can be difficult to interpret. The present study was undertaken to document radiographically the growth and development of the cervical spine in a prospective, longitudinal manner and to establish standard radiographic measurements on the basis of findings in patients who were followed serially from the age of three months until skeletal maturity. METHODS: The radiographic resources of the Cleveland Study of Normal Growth and Development (Bolton-Brush Collection, Cleveland, Ohio) were reviewed. From this large database, we identified fifty boys and forty-six girls who had a sufficient number of radiographs of the cervical spine for inclusion in our study. With use of a computerized image analyzer, the growth and development of the atlantodens interval, the diameter of the spinal canal, the Torg ratio, the height and width of the second through fifth cervical vertebral bodies, the height of the dens, and the ossification of the first cervical vertebra were assessed on serial radiographs made from the age of three months until skeletal maturity. RESULTS: Serial measurements of the atlantodens interval, the anteroposterior diameter of the cervical canal, the height and anteroposterior width of the cervical vertebral bodies, and the height of the dens, made in normal, healthy children from the age of three months to fifteen years, are presented in tabular and graphic forms. The median Torg ratio was 1.47 for both males and females primarily, and it reached values of 1.06 for males and 1.10 for females by maturity. The anterior arch of the first cervical vertebra had ossified in 33% of the children by the age of three months and in 81% of the children by the age of one year. Closure of the synchondroses was completed in all children by the age of three years. CONCLUSIONS: The measurements presented in the current study are important because they are the first, as far as we know, to document the radiographic parameters of the cervical spine in children who were followed longitudinally from before the age of three years through the course of growth and development until skeletal maturity.

The effect of freezing and intraosseous fluid on the stiffness behavior of canine trabecular bone.

The effect of disrupting the intraosseous fluid compartment and freezing on the mechanical stiffness of trabecular bone in intact canine femoral head specimens was investigated. Twenty-four skeletally mature dogs were divided into two groups. Twelve paired fresh femora were tested and 12 paired femora were tested after freezing at -20 degrees C. The intact femoral head specimens were subjected to a load of physiologic magnitude, and then the stiffness of the underlying trabecular bone was determined in intact femora, in drilled femora with a disrupted intraosseous fluid compartment, and subsequently after refilling the compartment with fluid. Drilling of the femoral head and disrupting its bony fluid compartment resulted in a 40% decrease in stiffness (P<.001). This effect was seen only with fresh specimens and not frozen specimens. Refilling the bony compartment with fluid restored the stiffness of the fresh femoral head. These results demonstrate the mechanical properties of trabecular bone in canine femoral head specimens in vitro are affected by intraosseous fluid and freezing. Removal of the intraosseous fluid decreases the mechanical stiffness of canine trabecular bone, and freezing the specimens appears to alter the intraosseous fluid compartment behavior. It is necessary to gain a better understanding of the dynamic mechanical properties of intact bone to improve the existing analytical and experimental mechanical bone models. The effect of intraosseous fluid and freezing should be considered in these models.

A symptomatic cyclops lesion 4 years after anterior cruciate ligament reconstruction.

The cyclops lesion is a fibrous nodule with central granulation tissue located anterolateral to the tibial tunnel after intra-articular reconstruction of the anterior cruciate ligament (ACL) that has been shown to be a cause of failure to regain full extension in the early postoperative period. We present the case of a 23-year-old woman who had undergone arthroscopic ACL reconstruction with a patellar tendon autograft 4 years prior to presentation. Following her reconstruction, she regained full range of motion and returned to collegiate cheerleading. At presentation, she complained of a gradual loss of full extension and joint-line pain with terminal extension. On examination, her graft was stable and she lacked 3 degrees of extension. Magnetic resonance imaging documented a 1-cm mass of low signal intensity immediately anterior to the ACL graft within the intercondylar notch. At arthroscopy, a large amount of thick, immobile scar tissue was found immediately anterior to the ACL, consistent with a cyclops lesion. The lesion was debrided and the patient did well postoperatively. Patients who present with delayed-onset loss of extension after ACL reconstruction should undergo careful evaluation including radiographs and magnetic resonance imaging. If a cyclops lesion is diagnosed, arthroscopic resection should be undertaken.

Body temperature and wheel running predict survival times in rats exposed to activity-stress.

The relationship between restricted feeding, core body temperature (Tb), wheel running, survival, and gastric erosion formation was examined in female rats exposed to activity-stress. Core body temperature and gross motor activity were telemetrically monitored in four groups of rats that had free access to running wheels and in one group that was not allowed to run on the wheels. Twenty-four hours prior to the onset of hypothermia and predicted mortality, different groups were left undisturbed, warmed with a heat lamp, denied access to running wheels, or euthanized. Length of survival in wheel-running rats varied from 2 to 12 days. During the first day of food deprivation, premorbid changes in the variability of Tb during the diurnal period and the mean number of wheel revolutions during the nocturnal period were strongly predictive of length of survival. Warming rats with a heat lamp or preventing rats from ever running on the wheel increased the length of survival and attenuated gastric erosion formation. Only rats that were warmed had a greater likelihood of survival. Gastric pathology was also reduced in rats that were euthanized prior to becoming moribund. Rats that were left undisturbed or locked from the running wheel over the last 24 h of testing became moribund and had extensive gastric mucosal damage. These results indicate that thermoregulatory disturbances induced by restricted feeding and not wheel running alone are critical in determining survival and the degree of gastric mucosal injury in rats exposed to activity-stress. Results further suggest that predisposing factors may put some rats at risk for the development of activity-stress-induced mortality.

Diagnosis of anterolateral ankle impingement. Comparison between magnetic resonance imaging and clinical examination.

We reviewed 22 patients who had arthroscopic evaluations and preoperative magnetic resonance imaging studies of their ankles because of chronic anterolateral ankle pain after sprains. The ability of surgeons to use the initial clinical examination to predict arthroscopically confirmed anterolateral ankle impingement was compared with the ability to predict this condition using preoperative magnetic resonance imaging. The patient population consisted of 15 men and 7 women who had an average age of 28 years. Five patients (23%) were intercollegiate athletes and 17 patients (77%) were recreational athletes. All patients reported previous traumas to the involved ankles, and all were seen with chronic ankle pain. Clinical examinations were used to assess ankle pain, swelling, range of motion, and stability. Anterolateral ankle impingement was confirmed in 18 patients (82%) with arthroscopic examination. Clinical examinations had a sensitivity of 94% and a specificity of 75% for predicting impingement, and magnetic resonance imaging had a sensitivity of 39% and a specificity of 50%. The results of this study suggest that preoperative magnetic resonance imaging examination is not beneficial or cost-effective in the diagnosis of anterolateral ankle impingement; furthermore, its use may cause further delay in treatment.

A prospective evaluation of a new physical examination in predicting glenoid labral tears.

We studied 62 patients (40 men and 22 women) with an average age of 28 years over a 28-month period who presented with shoulder pain that was refractory to 3 months of conservative management. Patients with a prior glenohumeral dislocation or a rotator cuff tear were excluded. The "crank" test was performed with the arm elevated to 160 degrees in the scapular plane of the body, loaded axially along the humerus, and with maximal internal and external rotation. Although similar tests have been described, the crank test is a new examination previously unreported. Half of the patients (31) had a positive crank test. Arthroscopy performed on all 62 patients revealed glenoid labral tears in 32 patients. Two patients who had positive crank tests did not have labral tears but had partial-thickness, articular-side rotator cuff tears. The sensitivity of the crank test was 91%, the specificity was 93%, the positive predictive value was 94%, and the negative predictive value was 90%. With these data, the crank test fulfills the criteria as a single physical examination test that is highly accurate for the preoperative diagnosis of glenoid labral tears. Accordingly, expensive imaging modalities currently used in this patient population may be employed less in the future.

Diagnosis of glenoid labral tears. A comparison between magnetic resonance imaging and clinical examinations.

We studied 54 patients with shoulder pain secondary to anterior instability or glenoid labral tears refractory to 6 months of conservative management with no evidence of rotator cuff lesions. All patients had sufficient preoperative clinical data, magnetic resonance imaging, and shoulder arthroscopy results for analysis. The ability to predict the presence of a glenoid labral tear by physical examination was compared with that of magnetic resonance imaging (conventional and arthrogram) and confirmed with arthroscopy. There were 37 men and 17 women (average age, 34 years) in the study group. Of this group, 64% were throwing athletes and 61% recalled specific traumatic events. Clinical assessment included history with specific attention to pain with overhead activities, clicking, and instances of shoulder instability. Physical examination included the apprehension, relocation, load and shift, inferior sulcus sign, and crank tests. Shoulder arthroscopy confirmed labral tears in 41 patients (76%). Magnetic resonance imaging produced a sensitivity of 59% and a specificity of 85%. Physical examination yielded a sensitivity of 90% and a specificity of 85%. Physical examination is more accurate in predicting glenoid labral tears than magnetic resonance imaging. In this era of cost containment, completing the diagnostic workup in the clinic without expensive ancillary studies allows the patient's care to proceed in the most timely and economic fashion. Glenoid labral tears have been associated with overhead throwing activities, trauma, and shoulder instability. Assessment of an athlete with shoulder pain should take into account a careful history of clicking sounds or catching, symptoms with overhead activities, reports of instability, or previous trauma. On physical examination, patients with labral tears often demonstrate objective instability with or without clicking or catching during glenohumeral rotation. Plain radiographs have not been helpful, and radiologists have relied on techniques from arthrogram to arthrotomogram, CT arthrogram, magnetic resonance imaging (MRI), and MR arthrogram to assist in the diagnosis. Various sensitivities and specificities have been reported for these tests. However, a large degree of intra- and interobserver variability has been demonstrated, and the degree to which these studies are helpful in preoperative planning has been questioned. No previous study to our knowledge has involved MRI in a direct comparison of other diagnostic modalities. Therefore, the purpose of this study is to investigate the accuracy of MRI and physical examination in the diagnosis of glenoid labral tears.