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Biomedical subjects

A Sarmiento

Publications and source records attributed to A Sarmiento.

At least 91 records · Page 5Linked to original sources
PubMed1989

Tibial shaft fractures treated with functional braces. Experience with 780 fractures.

We have reviewed our recent results with functional bracing of tibial shaft fractures in adults in order to define its role in management. We also analysed several parameters of these fractures to discover those which influence healing. A total of 780 tibial fractures treated in prefabricated functional braces were followed to union; shortening of less than 10 mm and angulation of less than 5 degrees in any plane were our parameters for successful treatment. The average time before applying a brace was 3.8 weeks for closed fractures and 5.2 weeks for open ones. Closed fractures healed in an average of 17.4 weeks and open fractures in an average of 21.7 weeks, 90% of them with 10 mm of shortening or less. Varus angulation and posterior angulation were the most common deformities encountered at union. There were 20 nonunions (2.5%) and 46 braces were discontinued during treatment. We found no association between fracture healing and the patient's age, the mechanism of injury or the fracture location. The degree of soft tissue injury appeared to have most influence on the speed of fracture healing. Fracture comminution and initial displacement, the condition of the fibula and the time from injury to bracing also appeared to affect the speed of union.

Adolescent↗
PubMed1988

An in vitro analysis of wrist motion: the effect of limited intercarpal arthrodesis and the contributions of the radiocarpal and midcarpal joints.

Radiocarpal and intercarpal arthrodeses were simulated in 12 fresh cadaver wrists by means of external fixation. Range-of-motion measurements were made before and after simulated arthrodesis and used to calculate the contribution of the midcarpal and radiocarpal joints to wrist motion, as well as the residual wrist motion after limited intercarpal arthrodeses. Relative contributions to wrist motion were as follows: wrist flexion: radiocarpal (RC) joint 63%, midcarpal (MC) joint 36%; wrist extension: RC joint 53%, MC joint 46%. The wrist motion remaining after simulated arthrodeses was as follows: capitate-hamate: flexion (Flx) 98%, extension (Ext) 92%, ulnar deviation (UD) 96%, radial deviation (RD) 90%; scaphoid-lunate: Flx 97%, Ext 91%, UD 90%, RD 91%; scaphoid-trapezium-trapezoid: Flx 86%, Ext 88%, UD 67%, RD 69%; scaphoid-lunate-triquetrum: Flx 91%, Ext 82%, UD 86%, RD 70%; capitate-lunate: Flx 70%, Ext 59%, UD 89%, RD 79%; capitate-hamate-triquetrum: Flx 88%, Ext 79%, UD 88%, RD 81%; hamate-triquetrum: Flx 90%, Ext 85%, UD 89%, RD 94%; scaphoid-trapezium-trapezoid-capitate: Flx 85%, Ext 77%, UD 64%, RD 57%.

Arthrodesis↗
PubMed1988

Immediate internal fixation of open ankle fractures.

Seventy-six consecutive displaced open ankle fractures were treated by immediate internal fixation between 1983 and 1986 at Los Angeles County University of Southern California Medical Center. Sixty-two patients were available for clinical and radiological examination at an average of 16.4 months post-fixation. Seventy-two percent of the patients had a satisfactory result. Poor results (20%) were most commonly due to non-anatomic reductions, articular surface damage, or deep infection. Deep infection occurred in 5% of the patients while 8% required late ankle arthrodesis. We believe immediate internal fixation is the treatment of choice for displaced open ankle fractures, but this form of treatment does have a significant rate of complications.

Adolescent↗
PubMed1988

Radiographic performance of two different total hip cemented arthroplasties. A survivorship analysis.

Detailed serial radiographic analysis of the femoral and acetabular components of 367 Charnley (cobalt-chrome alloy) and 383 STH (titanium alloy) primary cemented total hip prostheses was conducted. The follow-up of the Charnley prosthesis ranged from 1 to 16 years (mean follow-up, 9 years), and for the STH from 1 to 11 years (mean follow-up, 80 months). Both single period and survivorship analyses were done to evaluate the radiographic performance. The analysis revealed that the curved STH prostheses' overall radiographic performance was less satisfactory than the Charnley prostheses. However, the STH with a straight stem had significantly better radiographic performance compared with the Charnley prostheses in all parameters except in the incidence of bone-cement radiolucent lines.

Adolescent↗
PubMed1988

Synovial fluid osmolality in osteoarthritis and rheumatoid arthritis.

The osmolality of synovial fluid aspirated from the knees of 15 rheumatoid and 15 osteoarthritic patients was observed concurrently with the same measurement on blood serum. The group averages were compared to a group of 13 with identical apparati. Synovial fluid osmolality in rheumatoid arthritics (280 +/- 7.7 mmol/kg) was significantly different from that in osteoarthritics (297 +/- 16.9 mmol/kg), and both group averages were significantly different from normal (404 +/- 57 mmol/kg). Blood serum osmolality also differed between the normal and the two arthritic groups. The potential application of vapor pressure osmometry techniques in the diagnosis and management of joint disease is discussed.

Aged↗
PubMed1987

The role of subtalar motion and ankle contact pressure changes from angular deformities of the tibia.

It is a well known entity that fractures of the tibia heal with some component of angular deformity. Ankle and subtalar joints may compensate for small degrees of angular deformities, but the exact amount of malunion that can be accepted without development of late sequalae has yet to be determined. Two recent studies from this institution have concluded that contact changes at the tibiotalar joint tend to be greater with distal third tibial fracture deformities compared to proximal and middle with the ankle in neutral, 5 degrees dorsiflexion, and 20 degrees of plantar flexion. Anterior and posterior bow deformities produced a greater change in contact area of the tibiotalar joint than with valgus or varus deformities. This phenomena may be possibly explained by the subtalar motion in the horizontal plane which averages 23 degrees. Thus, it was the primary purpose of this paper to determine the exact role, if any, in subtalar motion on tibiotalar contact in angular deformities of the tibia. To achieve this objective the subtalar joint was transfixed thereby eliminating its perceived compensatory movement. Six cadaveric lower extremities were disarticulated at the knee joint and stripped of soft tissue preserving capsular and ligamentous structures. A custom universal joint was used to create various angulatory deformities at proximal, middle, and distal third levels of the tibia.(ABSTRACT TRUNCATED AT 250 WORDS)

Ankle Joint↗
PubMed1985

Radiographic analysis of a low-modulus titanium-alloy femoral total hip component. Two to six-year follow-up.

We performed a detailed serial radiographic analysis of the femoral component of 323 cemented low-modulus titanium-alloy total hip prostheses. There was a low incidence of femoral component loosening as manifested by radiolucent zones at the stem-cement interface or cement fractures. There was also a low incidence of resorption of the calcar and cortical hypertrophy. Comparison of our data with those of others indicated that the incidence of loosening, calcar resorption, and cortical hypertrophy was usually lower than with similarly designed conventional high-modulus Charnley stems. These findings appear to support computer-modeling studies that have predicted a more even distribution of stresses along the entire length of the stem of the titanium-alloy prosthesis. Of the two configurations of femoral components used, the straight stems demonstrated a significantly lower incidence of radiographic evidence of loosening, calcar resorption, and cortical hypertrophy than the curved stems did. These findings have provided sufficient biomechanical rationale for the evolutionary development of the second-generation femoral components, which incorporate many features of the straight stem.

Adolescent↗
PubMed1985

The stabilizing effect of soft-tissue constraints in artificial Galeazzi fractures.

Shortening of the radius is observed in Galeazzi (Piedmont) fractures and results from muscle pull after distal radioulnar joint disruption. A cadaver study was designed to examine the normal laxity at the distal radioulnar joint and contributions of the fibrocartilaginous complex (triangular ligament) and the interosseous membrane in prevention of proximal displacement of the distal radius fragment. It was found that up to 5 mm of radial shortening occurred after osteotomy alone. Shortening of over 10 mm did not occur unless both the interosseous ligament and the triangular ligament were sectioned. Some Galeazzi-type fractures may occur in the absence of distal radioulnar joint disruption, and others may result in disruption of the interosseous membrane of the forearm in addition to disruption of the triangular ligament at the wrist. Diaphyseal fractures of the distal radius may occur in several stages of severity. Attempts to produce a Galeazzi lesion by axial loading and pronation of the forearm above the dorsiflexed wrist caused a variety of injuries but did not result in an isolated fracture of the distal radius or disruption of the distal radioulnar joint.

Cadaver↗
PubMed1985

Changes in tibiotalar joint contact areas following experimentally induced tibial angular deformities.

Six cadaveric legs were stripped of all soft tissue excluding the interosseous membrane and the tissues about the ankle joint and foot. Angular deformities were simulated in all planes to a maximum of 15 degrees for proximal, middle, and distal third levels following tibial resection and same-level fibular osteotomy. Anterior ankle arthrotomies allowed exposure to the tibiotalar joint so that contact area could be measured with pressure-sensitive film inserted between the tibia and talus. An angular deformity of 15 degrees or less produced no significant alteration in the contact area of the ankle joint for proximal and middle third tibial levels. Distal tibial deformities showed a dramatic change in the contact area, with as much as a 42% decrease in contact area for anterior deformities. The contact shape for distal third angular deformities of 10 degrees and 15 degrees in all planes also tended to elongate, with a shift to more lateral contact noted. Although minor degrees of angular malalignment had little effect on ankle contact for proximal and middle third levels, it would appear that distal third deformities produce a greater change in ankle joint contact; thus, fractures at the distal level should be managed to minimize the possibility of tibial malalignment.

Ankle Joint↗
PubMed1985

Normal human synovial fluid: osmolality and exercise-induced changes.

We measured the osmolality of human synovial fluid in the knees of healthy young adults following minimum activity and exercise. These results were compared with each subject's blood-serum osmolality. The synovial fluid was hyperosmolal with minimum activity, decreasing to blood-serum levels after exercise.

Adult↗
PubMed1984

Prefabricated functional braces for the treatment of fractures of the tibial diaphysis.

We have reviewed our experiences with prefabricated functional braces in the treatment of diaphyseal tibial fractures. The braces were developed in an attempt to reduce the occasional technical difficulties encountered with the use of custom-made braces. Between January 1979 and July 1983 we treated 625 diaphyseal tibial fractures. One hundred and eighty-six patients (29.8 per cent) were lost to follow-up, the braces had to be discontinued in thirty-eight (9.2 per cent), and ten fractures (2.5 per cent) failed to unite. We conducted careful radiographic and clinical analyses of the remaining 391 patients. Two hundred and fifty-seven (65.7 per cent) of the fractures were closed and 134 (34.3 per cent) were open. Three hundred and fifty-seven (91.2 per cent) of the patients had ten millimeters of final shortening or less, and 306 (78.3 per cent) had a final angulation of 5 degrees or less. The average time from injury to bracing was 3.9 weeks (range, one to twelve weeks) for the closed fractures and 5.0 weeks (range, one to twelve weeks) for the open fractures. These findings appear to support our concept that function of the extremity is beneficial to osteogenesis and that many diaphyseal tibial fractures can be satisfactorily stabilized in prefabricated functional braces. These braces also have the advantage of not immobilizing the adjacent joints and they permit the gradual restoration of weight-bearing.

Adolescent↗
PubMed1984

[Results of 40 interfascicular grafting on peripheral nerve trunks].

The authors report 40 cases of interfascicular nerve grafts carried out since 1976 on the main peripheral nerves: 10 grafts of the median nerve, 21 grafts of the ulnar nerve, 8 grafts of the radial nerve and 1 graft of the sciatic nerve. In all cases, these are secondary grafts: either or first intention when the nervous section has been observed in emergency, the nervous ends being only brought together in these cases; or during an exploratory operation when faced by a lesion of unknown anatomical mechanism, These are interfascicular nerve grafts, according to Millesi, the donor nerve being represented by the sural nerve. The results, interpreted according to the criteria of the British Medical Research Council, are firstly analysed nerve by nerve, after discussion of age, level of injury, cause of injury, and above all, the delay between injury and the graft. The importance of associated damages is also discussed, specially vascular lesions. Several factors are influencing the quality of the results and among these are age, level and mechanism of the injury, the delay between injury and the graft, the length of the graft and number of cables. For that study, it is possible to conclude that the results are best when the patient is young, the delay short, the level distal, the length of the defect moderate and the number of cables is maximum. Finally, it appears from electrophysiological statements that this study is necessary to evaluate the quality of nervous regeneration, particularly at the median nerve, where the reinnervation is often supplied by the ulnar nerve (50% in our serie).

Adolescent↗
PubMed1984

The effects of function in fracture healing and stability.

A mechanically based classification system and hypothesis for fracture healing with peripheral callus has been proposed based on many years of clinical experience and numerous laboratory research studies. This hypothesis describes the interactions and influences on fracture healing from the vascular, mechanical, electric, chemical, and thermal environments in specific callus regions surrounding the fracture site. The central theme to this phenomenon is motion at the fracture site. The single factor distinguishing the effects of closed functional bracing of fractures from all other treatment modalities is motion between the fragments which results from early functional activity. Perhaps the stimulus to a prolonged inflammatory response is provided by friction between moving fracture fragments and the surrounding tissues. An increased vascular response results, and environmental factors are stimulated to form an abundant peripheral callus. Three distinct callus zones exist which provide overlapping stages of healing based on structure and optimized physiologic conditions. Clinical signs and symptoms, such as fracture stability as well as motion and pain at the fracture site, combine to provide the optimum feedback mechanism to control functional activity, which in turn governs environmental factors. Roentgenographic appearance can be better judged for mechanical significance if these three callus regions are appreciated. In animals as well as in humans, if function has correctly influenced the environment during callus formation, refracture strength is often greater than that of the original bone.

Animals↗
PubMed1984

The effects of angular and rotational deformities of both bones of the forearm. An in vitro study.

UNLABELLED: In intact fresh cadaver specimens, we experimentally studied angular and rotatory deformities at the distal and middle levels of the forearm. The remaining pronation and supination motions were measured. When both bones of the forearm were angulated with a combined deformity (radio-ulnar or dorsovolar, or both) of 10 degrees, a loss of pronation-supination of 12.5 +/- 4.5 per cent occurred in the forearms with a distal-third fracture; in the forearms with a middle-third fracture the average loss was 16.0 +/- 5.7 per cent. Pronation losses were similar for both distal and middle-third deformities. However, supination losses were much less affected (p less than 0.01) in forearms with deformities at the distal-third level while the losses were considered drastic for middle-third deformities. Rotatory deformities produced losses of pronation-supination that were equal to the degree of deformity. CLINICAL RELEVANCE: Study of the artificially created deformities in cadavera indicated that angular and rotatory deformities of the forearm of 10 degrees or less result in minimum limitation of pronation-supination. These degrees of limitation of motion in clinical practice are easily compensated for and are cosmetically acceptable. The fact that the perfect anatomical restoration of fracture alignment that often is obtained with internal fixation does not always result in complete restoration of motion suggests that: (1) this residual impairment of function is due to soft-tissue scarring, and (2) the mild angular and rotatory deformities resulting from nonsurgical treatment of fractures of the forearm may produce limitations of motion of an equally acceptable degree.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomechanical Phenomena↗
PubMed1984

Radiographic assessment of acetabular cup orientation. A new design concept.

An acetabular cup with a 270 degree rim wire has been designed to assist in the radiographic assessment of acetabular cup orientation in total hip arthroplasty. A study was conducted analyzing the component in various positions of lateral opening and version with three different X-ray-beam centering positions. The 270 degree acetabular rim wire allowed for easy and accurate assessment of component orientation when the pelvis was level and the central ray of the X-ray beam was centered over the hip.

Acetabulum↗