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Biomedical subjects

D L Fernandez

Publications and source records attributed to D L Fernandez.

At least 19 recordsLinked to original sources
PubMed2003

[Ulnar head prosthesis].

The ulnar head prosthesis has been the subject of a prospective multicenter-study since 1995. Until 2000, it has been used in 57 patients by the study group. In 35 patients, the indication was painful instability of the distal end of the ulna following previous resection arthroplasties, and in 22 patients it was painful arthritis of the distal radioulnar joint (DRUJ). The mean follow-up was 38 months. Pronation increased from a preoperative mean of 63 degrees to a postoperative value of 78 degrees, while supination increased from 43 degrees to 76 degrees. Grip strength improved from a preoperative mean of 51% to a postoperative mean of 77% of the opposite limb. Pain, measured on the verbal pain scale (1-4), was reduced remarkably from a preoperative mean level of 3.6 to a postoperative mean of 1.7. Patient' satisfaction was evaluated using the visual analog scale (0-10) and improved from a preoperative mean of 2.1 to a postoperative mean of 7.9. With one exception of loosening, we consistently found bony integration of the shaft of the prosthesis. Stability of the DRUJ was achieved in all but three patients. This method has given reliable and excellent results as a salvage procedure for failed resection arthroplasties of the DRUJ with painful instability of the distal end of the ulna. We consider the method an alternative treatment option for the arthritically destroyed DRUJ. Sufficient soft tissue to stabilise the prosthesis is needed to successfully reconstruct the DRUJ.

Adult↗
PubMed2002

Open reduction and internal fixation of un-united fractures of the distal radius: does the size of the distal fragment affect the result?

Two cohort populations consisting of 13 patients with an un-united fracture of the distal radius in whom the distal fragment had more than 5 mm of subchondral bone supporting the articular surface distal to the site of the nonunion and ten patients with an un-united fracture of the distal radius with a smaller distal fragment were compared. There were no preoperative differences with respect to age, gender, interval between injury and index procedure, preoperative amount of radius tilt, ulnar inclination and ulnar variance, or the preoperative function. Independent of the size of the distal fragment in all patients the distal radius was restored to gain bony union and realignment with preservation of some wrist motion. The length of the follow-up period averaged 30 months for the small fragment group compared with 22 months for the large fragment group. Bony union was achieved in 22 patients. One patient out of the large fragment group failed to heal the fracture and had wrist fusion. At the follow-up examination there were no significant differences in the radiological and clinical outcome between the two groups. No differences were seen on total range of motion of forearm supination and pronation with an average of 135 degrees in the large fragment group and 145 degrees in the small fragment group. Wrist motion revealed no significant differences in the flexion-extension arc, averaging 90 degrees in the large fragment group and 83 degrees in the small fragment group. Total range of motion of radial and ulnar deviation of the wrist was similar, averaging 39 degrees in the large fragment group and 43 degrees in the small fragment group. Grip strength averaged 59% compared with the opposite limb for the large fragment group and 67% for the small fragment group. We believe that the results of reconstruction of un-united fractures of the distal end of the radius for patients in whom the distal fragment had less than 5 mm of subchondral bone supporting the articular surface distal to the site of the nonunion are comparable to the results for patients with a larger distal fragment. Therefore, we believe that surgeons should try to preserve even a small amount of wrist motion and reserve wrist fusion as a final resort.

Adult↗
PubMed2002

Unstable scaphoid fracture nonunion: a medium-term study of anterior wedge grafting procedures.

A retrospective review of 37 patients with scaphoid fracture nonunions treated by interpositional bone grafting and internal fixation was conducted at an average follow-up of 5.7 years. Solid radiographic union was achieved in 35 cases. Preexisting avascular necrosis was a major adverse factor for achievement of union and satisfactory outcome. Based on the modified Mayo wrist-scoring system, 15 patients had an excellent result, 11 had a good result, four had a fair result and seven had a poor result. Patients with preexisting degenerative changes had a significantly worse clinical outcome. The vast majority of the patients had satisfactory correction of scaphoid length and the associated dorsal intercalated segment instability (DISI). Although 30 patients showed radiographic evidence of mild or moderate degenerative changes at their latest follow-up, there was no significant progression of arthrosis and the scaphoid nonunion advanced carpal collapse deformity did not progress after healing of the fracture nonunion.

Adult↗
PubMed2002

Melengestrol acetate blocks the preovulatory surge of luteinizing hormone, the expression of behavioral estrus, and ovulation in beef heifers.

We tested the hypothesis that melengestrol acetate (MGA), an orally active progestin, blocks estrus and the preovulatory surge of luteinizing hormone (LH) in beef heifers. Cycling yearling Angus heifers were divided randomly into two groups: MGA-treated (n = 6) and control (n = 5). All heifers received injections of prostaglandin F2alpha (PGF) on d -25, -11, and 0 to synchronize estrus. Following the last PGF injection on d 0, heifers were fed either 0.5 mg MGA in a carrier or the MGA carrier each day for 8 d. At 4-h intervals on d 1 through 6, all heifers were observed for expression of estrous behavior, and blood samples were collected and assayed for LH. Daily blood samples were collected at 0800 on d 1 through 10 and assayed for circulating progesterone concentrations. All control heifers exhibited estrus and a preovulatory surge of LH. In each case, this was followed by increases in circulating concentrations of progesterone indicative of ovulation and normal luteal function. In contrast, none of the MGA-treated heifers exhibited estrus, LH surges, or evidence of ovulation. The results of this experiment show that MGA prevents ovulation in cattle by inhibiting the preovulatory surge of LH.

Animals↗
PubMed2001

Distal radius fracture: the rationale of a classification.

A thorough review of both historical and contemporary classifications of distal radial fractures is presented. Critical analysis of older and newer classifications clearly shows the difficulty of including all the necessary parameters associated to a distal radius fracture in order to comprehensively assess the complexity of the lesion. The author has attempted to simplify the classification of distal radial fractures into five main groups according to the mechanism of injury. It includes the children fracture equivalent, the associated distal radioulnar joint lesions, and provides management recommendations. An alpha-numerical code is also provided for computer documentation.

Adult↗
PubMed2001

Surgical management of delayed union and nonunion of distal radius fractures.

Ten patients with malaligned fractures of the distal radius that demonstrated either delayed healing or the development of an atrophic or synovial nonunion on standard radiographs were treated with surgical realignment, stable internal fixation, and autogenous iliac crest bone grafting. All 10 fractures healed with acceptable radiologic alignment within 3 months of the index procedure. After an average follow-up period of 3 years 6 months (range, 2 years to 8 years 6 months) patients had an average of 105 degrees wrist flexion and extension, 145 degrees forearm rotation, and 73% grip strength compared with the opposite limb. In the treatment of malaligned, ununited fractures of the distal radius, specific techniques and implants must be tailored to the deformity of the distal radius and the shape of the distal fragment. A stable, well-aligned wrist with preservation of at least 50 degrees mobility in flexion and extension was achieved in every patient, but the final result was compromised by associated problems in 3 patients.

Adult↗
PubMed2001

Corrective osteotomy for symptomatic increased ulnar tilt of the distal end of the radius.

Twelve wrists in 10 patients with a mean age of 23.6 years were treated for symptomatic increased ulnar inclination of the joint surface with corrective osteotomy of the radius. Diagnoses included mild ulnar dysplasia, posttraumatic deformity, Madelung's disease, and multiple hereditary exostosis. All patients had radial-sided wrist pain and an ulnarly displaced arc of radioulnar deviation. Preoperative radiographs showed excessive ulnar inclination of the distal radius, ulnar carpal translation, adaptive carpal malalignment, and frequent distal radioulnar joint incongruency. The patients had decreased pain and improved wrist function at a mean of 5.1 years (range, 2-10 years) after surgery. Average radial deviation changed from 3 degrees to 16 degrees and ulnar deviation from 48 degrees to 29 degrees; flexion/extension and pronosupination remained unchanged. Realignment of the wrist was shown radiographically by a change of ulnar inclination of the radius from 33 degrees to 21 degrees, an increase in scaphoid height from 16.4 to 20.4 mm, and reversal of ulnar carpal translation as shown by an increase in lunate-covering ratio of 64% to 77%. Reduction of the ulnar inclination to normal values by corrective radial osteotomy restores a more physiologic range of motion, decreases symptomatic wrist pain, reverts adaptive carpal changes to normal, increases lunate coverage, and may prevent abnormal cartilage overload in the ulnar compartment of the wrist.

Adult↗
PubMed2001

Neurobiological mechanisms of the onset of puberty in primates.

An increase in pulsatile release of LHRH is essential for the onset of puberty. However, the mechanism controlling the pubertal increase in LHRH release is still unclear. In primates the LHRH neurosecretory system is already active during the neonatal period but subsequently enters a dormant state in the juvenile/prepubertal period. Neither gonadal steroid hormones nor the absence of facilitatory neuronal inputs to LHRH neurons is responsible for the low levels of LHRH release before the onset of puberty in primates. Recent studies suggest that during the prepubertal period an inhibitory neuronal system suppresses LHRH release and that during the subsequent maturation of the hypothalamus this prepubertal inhibition is removed, allowing the adult pattern of pulsatile LHRH release. In fact, y-aminobutyric acid (GABA) appears to be an inhibitory neurotransmitter responsible for restricting LHRH release before the onset of puberty in female rhesus monkeys. In addition, it appears that the reduction in tonic GABA inhibition allows an increase in the release of glutamate as well as other neurotransmitters, which contributes to the increase in pubertal LHRH release. In this review, developmental changes in several neurotransmitter systems controlling pulsatile LHRH release are extensively reviewed.

Animals↗
PubMed2001

Traumatic and reconstructive problems of the scaphoid.

The management of acute scaphoid fractures should be oriented on the concept of fracture stability, ease of reduction, associated ligamentous injury, and risk of impaired blood supply, rather than the direction of the fracture line or location of the fracture within the scaphoid. The lack of predictability of successful fracture union and prognostic discrepancies of historic and contemporary classifications may be related to subtle differences of the internal vascular architecture of each scaphoid. Because the possibility of impaired vascularity is greater with fractures located in the proximal third, stable internal fixation is indicated to provide mechanical stability and fracture surface contact to enhance revascularization. Improved healing rates in a shorter time and earlier rehabilitation with percutaneous techniques of internal fixation have produced a clear shift from classic conservative treatment to internal skeletal fixation. Although the rates of union of well-vascularized nonunions have not been dramatically improved with the use of internal fixation as compared with inlay bone grafting, the restoration of scaphoid anatomy and prevention of malunion and associated carpal collapse with interpositional bone grafting techniques will reduce the risk of osteoarthritis.

Bone Transplantation↗
PubMed2001

Scaphoid nonunion and malunion. How to correct deformity.

This article reviews the historical evolution of the assessment and understanding of the deformity of the nonunited and malunited scaphoid. The preoperative assessment, planning, and surgical technique for restoration of scaphoid anatomy are described. A brief presentation of our midterm and long term results obtained with interpositional wedge grafting is also discussed.

Bone Screws↗
PubMed2000

The treatment of complex carpal dislocations by external fixation.

This article presents the treatment of complex carpal dislocations and fracture dislocations by external fixation. Twenty-four patients were treated with external fixation after complex carpal trauma. Operative technique, aftertreatment, complications and long-term results are presented and discussed.

Adolescent↗
PubMed2000

Salvage of failed resection arthroplasties of the distal radioulnar joint using a new ulnar head prosthesis.

Twenty-three patients with painful instability following total or partial resection of the ulnar head were treated using a new ulnar head prosthesis combined with a simple soft tissue repair. Stability and marked symptomatic improvement were achieved in all patients. With a mean follow-up period of 27 months, this improvement has been maintained in all but 1 patient, whose prosthesis had to be removed because of a low-grade infection. These results suggest that the use of a prosthesis is a satisfactory way to restore stability and relieve secondary symptoms that may be associated with partial or total excision of the ulnar head.

Adult↗
PubMed2000

Should anatomic reduction be pursued in distal radial fractures?

Two articles on distal radial fractures in young adults are published in this issue of the journal. One reports the results of open reduction and internal fixation with the pi -plate in a group of patients in which the majority of fractures were complex and intraarticular. The other retrospectively assessed 169 fractures with an average follow-up of 4.9 years, based on the radiographic evaluation of the patient's X-rays until discharge and on the answers provided by a patient-based subjective outcome questionnaire. My task has been to comment, criticize and analyse the findings and results reported in both articles, in order to highlight areas of uncertainty and controversy regarding the current management of fractures of the distal radius in the younger age group.

Bone Plates↗
PubMed1998

Results of the modified Sauvé-Kapandji procedure in the treatment of chronic posttraumatic derangement of the distal radioulnar joint.

We reviewed the results of a modified Sauvé-Kapandji procedure with tenodesis of the flexor carpi ulnaris to the carpus in eighteen patients who had chronic derangement of the distal radioulnar joint. There were fourteen men and four women. The mean supination of the forearm had improved from 16 degrees (range, 0 to 75 degrees) preoperatively to 76 degrees (range, 40 to 90 degrees) at the time of the latest follow-up, and the mean pronation had improved from 42 degrees (range, 0 to 80 degrees) preoperatively to 81 degrees (range, 60 to 90 degrees) at the time of follow-up. Pain relief was satisfactory, and the mean grip strength had improved from 36 percent of that on the unaffected side preoperatively to 73 percent at the time of follow-up. One patient had moderate pain over the ulnar stump associated with residual volar instability of the proximal ulnar segment, and he had a tenodesis of the extensor carpi ulnaris as a second procedure. Another patient had mild instability of the stump only after he had a second operation, which was an excision of a bone mass (ossification) in the resected area. The ulnar stump was stable in sixteen patients. Eight of the eleven patients who had performed heavy manual labor before the injury were able to return to work full-time without restrictions. According to a modification of the wrist-scoring system of the Mayo Clinic, at a mean of four years and two months (range, two years to eight years and four months), six patients had an excellent result; seven, a good result; four, a fair result; and one, a poor result. On the basis of our findings, we believe that the index operation is an excellent salvage procedure for the treatment of chronic posttraumatic derangement of the distal radioulnar joint, especially when nonoperative treatment has been unsuccessful and rotation of the forearm is severely limited.

Adult↗
PubMed1997

Comparative classification for fractures of the distal end of the radius.

As suggested by Muller, a useful classification system for distal radius fractures must consider the severity of the bone lesion and serve as a basis for treatment and for evaluation of outcome. Although these fractures have long been considered to be Colles or Smith's fractures, they have been subjected to extensive scrutiny in order to define fracture morphology and treatment considerations. This review highlights a number of contemporary classification systems for distal radius fractures, including the systems of Older et al., the Comprehensive Classification of fractures, the Melone intra-articular classification system, and that of Fernandez.

Colles' Fracture↗
PubMed1997

Corrective osteotomy for malunited, volarly displaced fractures of the distal end of the radius.

Twenty-five patients who had had an opening-wedge osteotomy for the treatment of a malunited, volarly displaced fracture of the distal end of the radius were studied retrospectively. The indications for the operation were pain and functional limitations rather than the degree of anatomical deformity. Fifteen patients were men and ten were women; their average age was forty-six years (range, twenty-one to eighty-four years). Preoperative radiographs revealed an average ulnar inclination of 14 degrees, an average ulnar variance of five millimeters, and an average volar inclination of 24 degrees. Extension of the wrist averaged 25 degrees; flexion of the wrist, 53 degrees; supination of the forearm, 41 degrees; and pronation of the forearm, 64 degrees. The average grip strength was a force of seventeen kilograms compared with a force of forty kilograms in the contralateral hand. At an average of sixty-one months (range, eighteen to 114 months) after the osteotomy, supination of the forearm had improved to an average of 69 degrees and pronation had improved to an average of 75 degrees (p < 0.05 for both). Extension of the wrist had improved to an average of 55 degrees, and grip strength had improved to a force of thirty kilograms (p < 0.05 for both). Volar inclination averaged 5 degrees; ulnar variance, zero millimeters; and ulnar inclination, 22 degrees. A reoperation was performed in eleven patients. Seven patients had removal of the hardware only, two had a procedure involving the distal radioulnar joint, one had a procedure because the site of the osteotomy had not healed, and one had a median-nerve release. The functional result was rated as very good in ten patients, good in eight, fair in three, and poor in four.

Adult↗
PubMed1997

Fixation methods in contaminated wounds and massive crush injuries of the forearm.

This article presents a critical review of the current literature on the stabilization methods of severe open fractures or crush injuries of the forearm. Due to the complexity of the problem, the advantages and disadvantages of the different fixation methods are presented in order to provide the reader with a combination of possibilities for timing and decision-making when confronted with such fractures in clinical practice.

Bone Transplantation↗