Relationship between ligamentous laxity and the site of upper extremity fractures in children: extension supracondylar fracture versus distal forearm fracture.

Eighty children who had fallen on an outstretched hand and sustained either a displaced supracondylar fracture (group 1) or a displaced distal forearm fracture (group 2) were prospectively studied. Ligamentous laxity in these 80 patients was determined by four methods: (a) contralateral elbow hyperextension, (b) knee hyperextension, (c) the ability to touch the thumb to the ipsilateral forearm, and (d) the ability to extend the thumb past the ulnar border of the clenched fist. Elbow hyperextension averaged 10.5 degrees in group 1 and 4.4 degrees in group 2 (P < 0.0001). Knee hyperextension averaged 7.2 degrees in group 1 and 2.4 degrees in group 2 (P < 0.001). Twenty-one of 38 patients in group 1 (55%) compared with 8 of 42 patients in group 2 (19%) could touch the thumb to the ipsilateral forearm (P < 0.001). Twenty-seven of 38 patients in group 1 (71%) compared with 5 of 42 patients in group 2 (12%) could extend the thumb past the ulnar border of the clenched fist (P < 0.001). The authors conclude that a child who demonstrates ligamentous laxity is more likely to sustain an extension supracondylar humerus fracture than a distal forearm fracture when he or she falls on the outstretched hand to break the force of the fall.

The superiority of magnetic resonance imaging in differentiating the cause of hip pain in endurance athletes.

The accuracy of magnetic resonance imaging of the hip was prospectively evaluated in 19 military subjects engaged in endurance training. These patients had hip pain, negative radiographs, and radionuclide bone scans consistent with femoral neck stress fracture. Twenty-two hips were identified as positive for femoral neck stress fracture by bone scan. Each patient underwent magnetic resonance imaging and 6-week follow-up plain radiographs of the hips. Magnetic resonance imaging studies differentiated femoral neck stress fractures from a synovial pit, iliopsoas muscle tear, iliopsoas tendinitis, obturator externus tendinitis, avascular necrosis of the femoral head, and a unicameral bone cyst. The follow-up radiographs were used to verify the diagnosis of stress fracture. The radiographs showed healing callus in patients with stress fractures. Patients with diagnoses other than stress fractures had no changes on follow-up radiographs. Magnetic resonance imaging studies were as sensitive and much more specific than bone scan in determining the cause of hip pain. Radionuclide bone scan had an accuracy of 68% for femoral neck stress fractures with 32% false-positive results; MRI was 100% accurate. Magnetic resonance imaging proved to be superior to radionuclide bone scanning in providing an early and accurate diagnostic tool that aided in the differential diagnosis of hip pain in the young endurance athlete.

Disruption of the extensor mechanism in Paget's disease.

An unusual complication of Paget's disease is described wherein the extensor mechanism of the knee joint was disrupted because of avulsion of the patellar tendon from the tibial tubercle in a region of pagetic bone. The patient underwent successful surgical treatment of this condition.

Enzymatic histochemistry of mouse kidney in plastic.

Two-micrometer sections of methacrylate-embedded kidney were used to investigate the enzymatic activities of mouse kidney where the proximal tubule and Bowman's capsule from the same corpuscle were viewed in the same section. Alkaline phosphatase, acid phosphatase, 5'-nucleotidase, gamma-glutamyl transpeptidase, N-acetyl-beta-glucosaminidase, leucine aminopeptidase, alpha-naphthyl butyrate esterase, and adenosine triphosphatase activities were observed in the proximal tubule, but only 5'-nucleotidase, alpha-naphthyl butyrate esterase, and alkaline phosphatase were observed in the squamous portion of the parietal epithelium of Bowman's capsule. The use of methacrylate-embedded tissue allowed more precise localization of enzymatic activity than is possible with most frozen sections. This may provide interesting applications not only for characterization of kidney diseases but also for characterization of other normal and abnormal tissues.

Examination of enzyme-altered foci with gamma-glutamyl transpeptidase, aldehyde dehydrogenase, glucose-6-phosphate dehydrogenase, and other markers in methacrylate-embedded liver.

F344 Male rats weighting between 90 and 110 gm were given 90 ppm diethylnitrosamine in their drinking water for 5 weeks. Seven weeks after the administration of carcinogen was completed, the rats were sacrificed and sections of their livers were embedded in methacrylate. Serial sections 2 or 4 micron in thickness demonstrated the presence of gamma-glutamyl transpeptidase, acid phosphatase, adenosine triphosphatase, aldehyde dehydrogenase, alkaline phosphatase, alpha-naphthyl butyrate esterase, DT diaphorase, glucose-6-phosphate dehydrogenase, and 5'-nucleotidase activity and glycogen. The use of 4-micron sections of methacrylate-embedded tissue allows the evaluation of many more phenotypic markers in serial sections than is currently possible with frozen sections.