Osteocyte hypoxia: a novel mechanotransduction pathway.
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Bone is a unique tissue in which to examine mechanotransduction due to its essential role in weight bearing. Within bone, the osteocyte is an ideal cellular mechanotransducer candidate. Because osteocytes reside distant from the blood supply, their metabolic needs are met by a combination of passive diffusion and enhanced diffusion, arising when the tissue is loaded during functional activity. Therefore, we hypothesized that depriving a bone of mechanical loading (and thus eliminating diffusion enhanced by loading) would rapidly induce osteocyte hypoxia. Using the avian ulna model of disuse osteopenia, we found that 24 h of unloading results in significant osteocyte hypoxia (8.4 +/- 1.8%) compared with control levels (1.1 +/- 0.5%; P = 0.03). Additionally, we present preliminary data suggesting that a brief loading regimen is sufficient to rescue osteocytes from this fate. The rapid onset of the observed osteocyte hypoxia, the inhibition of hypoxia by brief loading, and the cellular consequences of oxygen deprivation are suggestive of a novel mechanotransduction pathway with implications across organ systems. (+info)
Osteoid osteoma. Direct visual identification and intralesional excision of the nidus with minimal removal of bone.
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We describe 100 consecutive patients with osteoid osteoma. Of the 97 who had operations, 89 were treated by intralesional excision and eight by wide resection. The three remaining patients were not operated on because the osteoid osteoma was almost painless, or was found in the pedicle of the 12th thoracic vertebra at the site of entrance of the artery of Adamkjewicz. The diagnosis was confirmed histologically in all specimens. No local recurrences were observed at a minimum follow-up of one year. All except one patient were mobilised two to four days after surgery. A precise preoperative diagnosis of the lesion is mandatory, based on clinical findings, standard radiographs, thin-section CT and a bone scan. We compared our operative technique with 247 cases in which the percutaneous technique of removal or coagulation of the nidus had been performed. The latter procedure has a less constant rate of primary cure (83% v 100%). Its principal indication appears to be for osteoid osteomas in the proximal femur and the pelvis. (+info)
Development of the human elbow joint.
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Many studies have been published on the development of the human elbow joint, but authors disagree on its morphogenetic timetable. Most discrepancies center on the cavitation of the elbow joint (including the humeroradial, humeroulnar, and superior radioulnar joints), and the organization of the tunnel of the ulnar nerve. We summarize our observations on the development of the elbow joint in 49 serially sectioned human embryonic (n = 28) and fetal (n = 21) upper limbs. During week 12, ossification begins in the epiphyses of the elements comprising the elbow joint. At the end of the embryonic period, the shallow groove between the posterior aspect of the medial epicondyle and the olecranon process, begins to be visible. The elbow joint cavity appears in O'Rahilly stage 21 (51 days) at the level of the humeroulnar and humeroradial interzones. Formation of the cavity begins at the medialmost portion of the humeroradial interzone and the lateralmost portion of the humeroulnar interzone. The annular ligament begins to develop in O'Rahilly stage 21 (51 days), and the superior radioulnar joint cavity appears between this ligament and the lateral aspect of the head of the radius during O'Rahilly stage 23 (56 days). We established the morphogenetic timetable of the human elbow joint. (+info)
New observations on carrying angle.
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Based on experiments on fresh cadaveric and accidentally amputated 8 upper limbs of children, study of ulnae for presence and absence of non articular strip on the trochlear notch, measurements of carrying angle, length of forearm bones, pronation-supination, height and weight in 2250 infants, children and adults of various age groups and clinical observations on 800 cases of injuries around elbow many new facts have been observed about the development of the carrying angle and its significance in the etiopathogenesis of various types of fractures seen around the elbow. The carrying angle develops in response to pronation of the forearm and is dependent on length of the forearm bones. Lesser the length of forearm bones greater is the carrying angle. So the carrying angle is more in shorter persons as compared to taller persons. It is abduction at the shoulder and not the carrying angle which keeps the swinging upper limbs away from the side of the pelvis during walking. Carrying angle is not a secondary sex character. The type of fracture a child sustains after fall on outstretched hand is also determined by the value of the carrying angle. A new type of fracture hitherto undescribed in the literature, T-Y fracture of the distal humeral epiphysis is also reported. (+info)
The Sauve-Kapandji procedure for post-traumatic disorders of the distal radio-ulnar joint.
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We present the results of a retrospective series of 41 Sauve-Kapandji procedures carried out for complications of fractures of the distal radius. All the operations were undertaken by one surgeon with a mean follow-up of 32 months. A total of 37 patients was available for clinical review. The indications for surgery were pain on the ulnar side of the wrist and decreased rotation of the forearm. Intraperiosteal and extraperiosteal techniques were used for resection of the ulna, with no difference in outcome. Patients were assessed for pain, rotation of the forearm and complications. A Mayo Modified Wrist Score was used. Pain was improved in 25 of the 37 patients, and unchanged in ten. Rotation of the forearm returned to within 7 degrees of the uninjured side. The results are discussed in relation to the presence of preoperative malunion of the distal radius, age and the functional outcome. Age is not a contraindication for this procedure. (+info)
The anatomy of the metacarpo-phalangeal joints, with observations of the aetiology of ulnar drift.
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One hundred normal fingers were dissected and arthrographs obtained by injection of chromopaque-gelatin mixture, allowing comparison between the radiographic and macroscopic configuration of the synovial capsule. Synovial recesses protruding from each side of every metacarpo-phalangeal joint were found in relation to the collateral ligaments and corresponding exactly with the site of radiological erosions. A group of bursae lying on the superficial aspect of collateral ligaments were also demonstrated. A rudimentary intra-articular meniscus was found. The results of examination of the insertions of the interossei showed differences from traditional descriptions. The cause of rheumatoid deformity was suggested to be the rheumatoid process arising in the lateral recesses and lateral bursae, weakening the collateral ligaments, which give way in the directions of the deforming forces. These are derived from the long flexor tendons, which were shown to exert an ulnar and volar strain on the metacarpo-phalangeal joint of every finger during grip. (+info)
Hemophilic pseudotumor of the ulna treated with low dose radiation therapy: a case report.
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We report a case of hemophilic pseudotumor in the ulna of a 6-year-old boy treated with radiation therapy. A total dose of 900 cGy in 6 fractions was given in 6 consecutive days. Progression of cystic changes was halted within a month. New bone formation and trabeculation were found on the 4th month. Complete healing of the lesion and bony replacement were found on the 12th month. The patient was followed up to 72 months and there was no evidence of recurrence and no bone growth disturbance. Radiation therapy can be an effective alternative modality in treating hemophilic pseudotumor. (+info)
A study of articular surfaces and synovial fossae of the pectoral limb of swine.
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Articular surfaces of the pectoral limb were studied in 50 swine and are described in detail. Synovial fossae were not present at birth but were found commonly on the articular surface of the scapula, distal humerus, proximal radius, distal radius and distal surfaces of the intermediate carpal bone after four to five months of age. When present, they were bilaterally symmetrical and were located at the depth of a concavity of the articular surface. Microscopically, synovial fossae appeared as an invagination of articular cartilage extending into subchondral bone. Evidence of endochondral bone formation was less apparent at the depth of synovial fossae than in areas of weight bearing cartilage. (+info)