Biomedical subjects

D R Pichora

Publications and source records attributed to D R Pichora.

24 records · Page 2Linked to original sources

PubMed1991

Rotational step-cut osteotomy for treatment of metacarpal and phalangeal malunion.

Metacarpal and phalangeal malunion after fracture or replantation frequently causes rotational deformities with scissoring during digital flexion. Transverse osteotomy at the metacarpal base has been advocated for derotation, but this only partially corrects scissoring resulting from phalangeal malunion. We describe the results of rotational step-cut osteotomies at the site of malunion. There were twenty-three osteotomies in eighteen patients; seven metacarpal and sixteen in the proximal phalanx. The value of the technique is supported by the results; speedy healing of bone, satisfactory alleviation of deformity, and a useful gain in range of motion in many patients.

Adult↗

PubMed1990

External iliac artery and lumbosacral plexus injury secondary to an open book fracture of the pelvis: report of a case.

Lumbosacral plexus or external iliac artery injuries associated with pelvic fracture are reported rarely in the literature. A case involving a noncompound open book pelvic injury with diastasis of the symphysis pubis and combined ipsilateral lumbosacral plexus and external iliac artery injury is reported. Repeated clinical examination to diagnose vascular lesions with evolving pulse deficits is emphasized.

Adult↗

PubMed1989

Surgical anatomy of the medial antebrachial cutaneous nerve.

In standard anatomy textbooks the course and distribution of the medial antebrachial cutaneous nerve and its branches are glossed over in a vague fashion as if they are of little importance. There are, however, clinical circumstances in which a knowledge of the anatomy of this nerve is invaluable. Sacrifice of the posterior branch in a medial approach to the elbow or cubital tunnel surgery can lead to annoying numbness over the olecranon and a symptomatic neuroma. The medial antebrachial cutaneous nerve is also frequently used in nerve grafting, especially in brachial plexus reconstruction, in which it is beneficial to know the available length and size of donor nerve. Fifty fresh cadaveric arms were dissected to define the course, distribution, size, and branches of the nerve.

Arm↗

PubMed1989

Gamekeepers thumb: a prospective study of functional bracing.

Patients with acute thumb metacarpophalangeal joint injuries were assessed by stress radiography, arthrography, and clinical examination. Arthrograms served to assess tissue injury by the extent and location of dye leaks including the differentiation of displaced (Stener lesion) from undisplaced tears of the ulnar collateral ligament. Patients were treated for a minimum of 6 weeks by use of a removable custom-fit splint and daily range of motion exercises, and followed at a minimum of 1 year. In the 32 patients available for follow-up, mean relative instability improved from 17 degrees (after injury) to 2.3 degrees (follow-up) (p = 0.0001). Functional and subjective outcomes were good or satisfactory in more than 90% of patients; outcomes for all patients with Stener lesions were satisfactory, although joint stabilization was less than in the whole group. The three failures involved persistent symptoms, that defied subsequent surgery. These cases could not be predicted from the initial clinical tests. The treatment regimen was an economical, noninvasive, and effective method for a range of acute thumb metacarpophalangeal joint injuries.

Adolescent↗

PubMedDate not supplied

Mechanical testing of shoulder prostheses and recommendations for glenoid design.

Glenoid component loosening generates the greatest concern among surgeons performing total shoulder arthroplasty. Laboratory testing of glenoid prostheses may lead to improved design, subsequently leading to a reduction in the incidence of clinical loosening. The goals of this study were to develop a laboratory test method to address glenoid loosening and to apply this method to a variety of prosthesis designs. With use of a biaxial apparatus, glenoid components were cyclically subjected to superoinferior edge loading, mimicking the off-center rocking-horse phenomenon thought to contribute to glenoid loosening clinically. Before and after the rocking test was performed, compression and distraction of the superior and inferior edges were measured with the humeral head displaced to each edge. Rocking performance could not be predicted from initial measurements, indicating the necessity for dynamic loading to evaluate the likelihood of loosening. A roughened fixation surface for outperformed a smooth fixation surface, a curved backing showed almost half the distraction of a flat backing, and a nonconstrained prosthesis distracted less than a more constrained prosthesis.

Arthroplasty↗

PubMedDate not supplied

Shoulder prosthesis subluxation: theory and experiment.

The articular shapes of the humeral and glenoid components in total shoulder arthroplasty affect the loading, translation, and contact stresses in the joint, thereby affecting stability, glenoid loosening, and wear. Experiments were conducted to determine the subluxation load and corresponding translation for 6 types of glenoid components. The effects of shape, size, testing direction, compressive load, testing speed, testing medium, bone substitute properties, and repeated subluxations were investigated and compared with theoretical, rigid-body predictions. The subluxation load, varying from 45% to 98% of the axial load for the prostheses tested, is affected by glenoid constraint (i.e., the maximum slope at the glenoid articular rim), the compressive load, the coefficient of friction, and the deformability of the articular edge. Rigid-body theory overestimated the experimental load, which was not surprising given the visible deformations, but provides a framework to highlight the relevant design parameters. The subluxation translation, ranging from 1 to 13 mm for the prostheses tested, is determined by the glenoid length and by the conformity between the humeral and glenoid radii. Experimental translations were greater than rigid-body predictions for the most conforming prostheses and roughly equal for less conforming prostheses. The goals of this study were to characterize the subluxation load and translation of a variety of types of prostheses, to develop the rigid-body basis for these results, to compare the rigid-body and experimental results, and to locate experimentally the glenoid articular rim for further testing.

Biomechanical Phenomena↗