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We describe a new procedure for the management of chronic posttraumatic radial head dislocation, which uses two drill holes in the proximal ulna. The holes are placed at the original attachments of the annular ligament and thereby allow repair of the annular ligament (frequently avulsed from one attachment and impinged within the joint) or reconstruction of the annular ligament with whatever tissue or material desired (triceps tendon is convenient). It secures the radial head in its normal position from any dislocated position. It also allows for osteotomy of any accompanying deformity of the ulna or radius. This operation developed gradually between 1967 and 1995 while we treated seven female patients. The average age at time of injury was 5 years 10 months (range, 3 years 4 months to 8 years 11 months). The interval between injury and operation averaged 30 months (range, 3 months to 7 years). The age at time of surgery averaged 8 years 4 months (range, 5 years 4 months to 13 years 5 months). The only criterion for surgery was a normal concave proximal radial articular surface. Follow-up averaged 48 months. At final follow-up, all patients were fully active and had no elbow pain or instability. Analysis of these cases suggests that the criteria for surgical repair should be based on two features: (a) normal concave radial head articular surface, and (b) normal shape and contour of the ulna and radius (deformity of either should be corrected by osteotomy). The age of the patient and duration of the dislocation are unimportant.

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Sixty consecutive patients undergoing a primary hybrid total hip arthroplasty were randomized to receive a femoral component either with or without a distal centralizing device. The group with a centralizer had significantly fewer patients with cement mantle deficiencies (excessively thin areas of cement) than the group without a centralizer (P < .001). Furthermore, the centralizer group was, on average, in a neutral alignment, whereas the group without a centralizer was in a varus alignment (P < .001). It was concluded that the distal centralizing device significantly decreases the incidence of cement mantle deficiences and reproducibly aids in achieving a more neutral prosthetic alignment.

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The posterior condylar surfaces of the femur are routinely used as the reference for the rotational orientation of the femoral component during most primary total knee arthroplasties. The purpose of this investigation was to identify a clearly discernible, reproducible secondary anatomic axis useful for determining the rotational orientation of the femoral component when the posterior condylar surfaces cannot be used. Seventy-five embalmed anatomic specimen femurs were studied. A surgical epicondylar axis was defined as the line connecting the lateral epicondylar prominence and the medial sulcus of the medial epicondyle. The posterior condylar angle was measured as the angle between the posterior condylar surfaces and the surgical epicondylar axis. Measurement of the posterior condylar angle referenced from the surgical epicondylar axis yielded a mean posterior condylar angle of 3.5 degrees (+/- 1.2 degrees) of internal rotation for males and a mean posterior condylar angle of 0.3 degree (+/- 1.2 degrees) of internal rotation for females. Thus, rotational alignment of the femoral component can be accurately estimated using the posterior condylar angle. The posterior condylar angle, referenced from the surgical epicondylar axis, provides a visual rotational alignment check during primary arthroplasty and may improve alignment of the femoral component at revision.

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This investigation determined the position of neurologic and vascular structures at risk during screw fixation of an uncemented tibial component in total knee arthroplasty relative to the cut surface of the tibial plateau. Sixteen anatomic specimens of the lower extremities were studied by systematically placing screws about the tibial plateau followed by computed tomographic scanning with three-dimensional reconstruction and anatomic dissection. The structures at risk during screw preparation and placement were the tibial nerve, popliteal artery, popliteal vein, anterior tibial artery, and common peroneal nerve with its superficial and deep branches. The application of a clock system to the cut surface of the tibial plateau with the six o'clock position defined as directly anterior and the three o'clock position defined as lateral identified the entire region between the 11 o'clock and three o'clock positions as a location where potential injury to vital structures can occur during screw placement. The risk of injury to these structures may be minimized by directing screws radially inward to avoid violation of the tibial cortex. Any penetration of the cortex between the 11 o'clock and three o'clock positions may have potentially devastating consequences because of the close proximity of neurologic and vascular structures.

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Though many anatomic and biomechanical studies have been performed to elucidate capsuloligamentous anatomy of the glenohumeral joint, no previous studies have evaluated capsuloligamentous anatomy during rotator cuff contraction. The purpose of this study was to define and document the orientation and interrelationship between the glenohumeral ligaments during simulated rotator cuff contraction. Six fresh cadaveric shoulders were arthroscoped to document and grade ligamentous anatomy. The superior and middle glenohumeral ligaments and the anterior and posterior bands of the inferior glenohumeral ligament complex were labeled by an arthroscopicassisted technique with a linked metallic bead system. Shoulders were then placed onto an experimental apparatus that simulated rotator cuff function through computer-controlled servo-hydrolic actuators attached to the rotator cuff and biceps by a clamp and cable-and-pulley system. Simulated rotator cuff action and manual placement allowed shoulders to be placed into three positions of rotation (neutral, internal, and external) in three positions of scapular plane abduction (0°, 45°, 90°). Anteroposterior and axillary lateral plane radiographs were taken in each position to document orientation of all four ligaments. Both the superior and middle glenohumeral ligaments were maximally lengthened in 0° and 45° abduction and external rotation and appeared to shorten in all positions of abduction. The anterior and posterior bands of the inferior glenohumeral ligament complex maintained a cruciate orientation in all positions of abduction in the anteroposterior plane, except at 90° abduction and external rotation, where they are parallel. This cruciate orientation is due to the different location of the glenoid origin and humeral insertion of each band and may allow reciprocal tightening of each during rotation. The glenohumeral capsule is composed of discreet ligaments that undergo large charges in orientation during rotation. The superior and middle glenohumeral ligaments appear to complement the inferior glenohumeral ligaments, with the former tightening in adduction and the latter tightening in abduction. This relationship permits the large range of motion normally seen in the glenohumeral joint.

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Investigated the morphogenesis of the nasal structures of the chondrocranium and determatocranium in 15 embryos and foetuses of the sperm whale (Physeter macrocephalus). In the very early stages of the morphogenesis, the nasal capsule of Physeter shows a conspicuous similarity with that of all other odontocetes. In the following stages there are some important differences. Most peculiar is the occurrence of the cartilaginous tectum nasi with the cupulae nasi anteriores, elements which are reduced in all other odontocetes. This cartilaginous complex as a slender band projects obliquely forward from the upper edge of the anterior septal margin. It is free, i.e. not accompanied by membraneous bones. The complex represents the most important factor in the morphogenesis and growth of the characteristic big forehead in Physeter, which contains the spermaceti organ unique within the odontocetes. Other important differences concern the changes in the orientation of the nasal passages and the adjacent skeletal structures. Nevertheless, these differences have to be taken as specializations related to the development of the far-advanced spermaceti organ. As a whole, the embryonic nasal structures in Physeter belong to the same general type of nasal capsule which is common to all odontocetes. The results presented here suggest a close phylogenetic relationship between Physeter and the other Odontoceti.

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