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Biomedical subjects

R J Haddad

Publications and source records attributed to R J Haddad.

At least 37 records · Page 2Linked to original sources
PubMed1987

Wrist arthroplasty: a retrospective study.

A retrospective study was conducted to evaluate the long-term effectiveness of wrist arthroplasties in patients with various arthritic conditions. A total of 39 wrist arthroplasties were performed in 29 patients (average age, 52.5 years) by the orthopedic staff at Tulane University School of Medicine. Rheumatoid arthritis was the major presenting diagnosis in 84.6% of these operative cases and pain was the most common indication for surgery (79.5%). Postoperative relief of pain was reported in all of the cases reviewed, with an average follow up period of 51.2 months (range, 12 to 118 months). A group of 15 patients who were examined clinically had an average grip strength of 19.2 lb (range, 6 lb to 45 lb). Pinch measurements averaged 1.9 lb and arc of motion averaged 59.5 degrees (range, 20 degrees to 100 degrees) for these patients. Postoperative complications included dislocation (3 cases), fracture of the prosthesis (2 cases), and infection (2 cases). No complications were observed in 32 (82.1%) of the 39 cases reviewed. This retrospective study revealed that at an average follow up period of 51.2 months, pain relief was excellent and patient acceptance was good, with 94.9% of the wrists having been improved by the procedure. The majority (82.1%) of the cases were free of complication. It is concluded from this study that wrist arthroplasty is a viable alternative to wrist arthrodesis.

Adult↗
PubMed1987

Fatigue failure of the femoral component of a unicompartmental knee.

A unicompartmental knee implant was retrieved after 11 years in situ. The cast stainless steel femoral component had fractured approximately 1 cm from the anterior tip. The implant and clinical tolerance were analyzed to ascertain the factors associated with the mechanical failure. Increased tensile stresses owing to poor surgical placement and wear on the weight-bearing surface of the component, together with the quality of implant material, influenced the mechanical failure. Examination of the fracture surface revealed fatigue to be the mode of failure. Microscopic analysis of sections through the specimens showed a high inclusion content and inhomogeneous grain size, typical of the cast stainless steel from which the femoral component was fabricated.

Female↗
PubMed1987

Optimum pore size for bone cement fixation.

The interface shear properties of porous coated Ti-6Al-4V alloy embedded in bone cement were examined as a function of pore size. Cylindric Ti-6Al-4V alloy push-out specimens were coated with two layers of spheric powders having particle size ranges of 297-420 microns, 420-500 microns, 595-707 microns, and 850-1400 microns. Sintering resulted in mean pore sizes of 165, 285, 345, and 550 microns, respectively, and porosities in the range of 40%-44%. There was a statistically significant difference between the mean pore sizes obtained from the four particle size ranges. There were no differences between the mean porosities. The porous-coated specimens were embedded in bone cement and mechanical push-out testing was performed. Non-coated specimens having a satin surface finish were also embedded in bone cement and tested. The noncoated metal specimens displayed an interface shear strength of 4.2 +/- 0.4 MPa, whereas the shear strengths for the porous-coated specimens were significantly higher and increased as pore size increased. The mean interface shear strengths determined were 17.0 +/- 2.1 MPa (165 microns pore size), 18.1 +/- 2.3 MPa (285 micron pore size), 23.6 +/- 1.7 MPa (345 microns pore size), and 25.4 +/- 3.4 MPa (550 microns pore size). Significant differences in shear strength for the porous-coated specimens were found between the two smaller particle sizes and the two larger particle sizes. As pore size increased from 285 microns to 345 microns, a statistically significant increase in shear strength from 18.1 MPa to 23.6 MPa was observed.

Alloys↗
PubMed1986

The effect of post-sintering heat treatments on the tensile properties of Ti-6A1-4V alloy.

Previous studies have shown that the application of a porous coating to a solid substrate offers several advantages over current methods of implant fixation. However, the heat treatments required to sinter porous metal coatings have also been shown to cause significant decreases in the mechanical properties of the substrate. With Ti-6A1-4V alloy, sintering above the material beta transus results in a transformation from the as-received, equiaxed microstructure, recommended for surgical implants, to a lamellar alpha-beta microstructure. This lamellar structure has been shown to have inferior mechanical properties. In the present study, microstructural analysis and mechanical testing were performed on Ti-6A1-4V alloy subjected to various post-sintering heat treatments in an attempt to improve the mechanical properties. The microstructures examined were a fine and a coarse acicular alpha in a retained beta matrix. Tensile tests were performed on specimens containing these structures and results were compared with the lamellar and equiaxed microstructures. The fine acicular alpha structure was shown to exhibit the best tensile properties for the post-sintering Ti-6A1-4V alloy microstructures examined, displaying a 9.8% elongation value, as compared to the as-received, equiaxed microstructure value of 13.5%. This represents a significant improvement over the 5.1% value obtained with the lamellar microstructure.

Alloys↗
PubMed1986

Histologic and microradiographic analysis of a revised porous-coated anatomic (PCA) patellar component. A case report.

A retrieved uncemented, porous-coated human patellar component was evaluated histologically and microradiographically. The metal portion of the component and porous coating were made of cobalt--chromium-based alloy. Because of adhesive capsulitis and inadequate knee flexion, the patient had revision surgery 11 months after the original total knee arthroplasty. Clinically, the device was not grossly loose. Contact microradiography of the porous material showed no calcified tissue ingrowth. Undecalcified histologic sections demonstrated only fibrous tissue ingrowth, with obvious bone-resorptive activity as well as numerous multinucleated giant cells adjacent to the porous metal.

Bone and Bones↗
PubMed1986

Fractures and dislocations of the metacarpals and phalanges.

Hand injuries in athletes are very common and usually do not prevent active participation in sports. For this reason, long-term permanent disability and permanent loss of function may develop if these injuries are not recognized and treated properly. The majority of metacarpal and phalangeal joint injuries respond well to closed aggressive early treatment, followed by intensive therapy and protective splinting, which allow the athlete to continue his or her sport participation without the undesirable effects of long-term or permanent loss of function to the hand.

Athletic Injuries↗
PubMed1985

Aztreonam in the treatment of serious orthopedic infections.

Aztreozam was evaluated in the treatment of a variety of orthopedic infections. Included were 17 patients with osteomyelitis, three with purulent arthropathy with prostheses, and 16 with superficial infections secondary to trauma or surgical procedure. Pathogens were gram-negative bacilli sensitive to aztreonam. Concomitant antibiotics were administered for gram-positive cocci that were present initially or by superinfection. Infecting organisms included Pseudomonas aeruginosa (minimal inhibitory concentration 4 to 16 micrograms/ml), Serratia marcescens, Enterobacter cloacae, Enterobacter sakazakii, Morganella morganii, Citrobacter freundii, Proteus vulgaris, Proteus rettgeri, Acinetobacter calcoaceticus and others (all with minimal inhibitory concentrations less than 1.0 microgram/ml). Dosage of aztreonam was 2 to 8 g per day administered intravenously or intramuscularly for five to 52 days. Clinical and bacteriologic responses were adequate in all instances. Recurrences were observed in two individuals with osteomyelitis and one with purulent arthropathy. Adverse clinical or laboratory observations were infrequent and inconsequential.

Adult↗
PubMed1985

The effect of surface treatments on the interface mechanics of LTI pyrolytic carbon implants.

A mechanical and histological evaluation of LTI pyrolytic carbon implants was undertaken to determine the effect of various surface treatments on the retention characteristics of the implants. Five types of surfaces were evaluated, including as-deposited, fine grit-blasted, coarse grit-blasted, ground, and plasma oxygenated. The four surface treatments were chosen in an attempt to emulate the morphology of the as-deposited implants. The implants were evaluated in vivo by placement transcortically in the femora of adult mongrel dogs for periods of 12 to 24 weeks. Although the as-deposited implants exhibited the greatest interface strength at 12 weeks the results of mechanical testing after 24 weeks implantation indicated no statistically significant difference among the interface strength values or among the interface stiffness values of the implants. The histologic response of the implants was similar; while all implants exhibited areas of direct implant-bone apposition, the as-deposited implants exhibited this behavior to the greatest extent. Thus the ability to duplicate the biological response to the as-deposited LTI carbon surface appears possible by one or more of the treatments evaluated.

Animals↗
PubMed1985

Post-sintering heat treatments for porous coated Ti-6A1-4V alloy.

Previous studies have shown that the application of a porous Ti-6A1-4V alloy coating results in a substantial decrease in the substrate material fatigue properties. This phenomenon is due to both a microstructural change from the equiaxed alpha-beta microstructure to a lamellar structure and a notch effect created by the porous coating. The lamellar microstructure has been shown to exhibit the worst fatigue properties of the most common structures obtained in Ti-6A1-4V alloy. This study examined various post-sintering heat treatments which would alter the material microstructure and possibly result in improved fatigue performance. The heat treatments examined produced alternate microstructures to the lamellar structure and some approached the totally transformed acicular alpha structure. The acicular alpha structure has been shown to exhibit the best fatigue properties for Ti-6A1-4V alloy in the notched condition.

Alloys↗
PubMed1985

Interface mechanics and bone growth into porous Co-Cr-Mo alloy implants.

The interface mechanics and bone growth into porous Co-Cr-Mo alloy implants were evaluated. Three mean pore sizes (155, 235, and 350 microns) were studied for implants fabricated with one, two, and three layers of spherical powder particles and totally porous implants. All implants had a pore volume of 38%-40%. Ten implants were inserted transcortically in the femora of six adult mongrel dogs and were allowed to remain in situ for a period of 12 weeks. Postretrieval mechanical testing and histologic and microradiographic analyses were used to evaluate the implant systems. A statistically significant increase in interface shear strength (p less than .05) was determined as the number of powder particle layers was increased from one and two layers to three layers. However, a decrease in interface strength was determined for totally porous implants (seven to 12 particle layers) below the value for the single-porous-layer implants. Pore size, in the range investigated, was not found to influence the interface attachment strength. Neither pore size nor porous layer thickness was found to affect interface stiffness. Histologic and microradiographic sections revealed extensive mineralized bone growth deep into the pores of all implant types and often extending to the core of the one-, two- and three-layered porous-coated implants. Both mature haversian bone and less mature woven bone were found within the porous structure. Extensive but incomplete bone infiltration was found in the totally porous implants, with the remainder of the porosity filled with macrophage-laden connective tissue. No difference in the histologic response was observed as a function of pore size in any of the implant systems. Active bone labels were present at the 12-week time period, indicating continued bone remodeling.

Animals↗
PubMed1985

Clinical and metallurgical analysis of retrieved internal fixation devices.

The clinical performance, corrosion characteristics, and metallurgical properties of 82 retrieved stainless-steel bone plates have been examined. The plates had been in situ for periods ranging from one to 169 months. Only 29% of these devices (24 of 82 plates) were removed on a routine asymptomatic basis, while 62% (51 of 82 plates) were removed for cause-related reasons such as implant-related pain, infection, nonunion or malunion, and so forth; seven plates were removed for unknown reasons. Although most patients who had plates removed for pain reported some improvement in symptoms, others felt no improvement after removal. On examination, over 89% of the recovered implants displayed some degree of either surface (pitting) or screw-plate interface (crevice and fretting) corrosion or both. Statistical analyses revealed that the metallurgical properties of grain size and nonmetallic inclusion content correlated significantly with the degree of both types of corrosion.

Bone Plates↗
PubMed1985

A clinical and metallurgical analysis of retrieved Jewett and Richards hip plate devices.

The metallurgical properties of 61 retrieved 316L stainless steel (ASTM F138-76) hip plate devices used for the treatment of intertrochanteric fractures were examined. Surface and screw-plate interface corrosion characteristics were graded, and grain size, inclusion content, and hardness values were measured. These measurements were then correlated with the clinical performance of the devices. The devices studied included 21 Jewett nail-type and 40 Richards compression screw-type hip plates. The devices had been in situ an average of 26.7 months, with in situ periods ranging from 2.0 to 156.0 months. Cause-related reasons represented the majority of removals (89.8%), while only 10.2% of the hip plates were removed on a routine asymptomatic basis. The data suggest that surgeons consider this type of device as a permanent implant, with removal undertaken only for causative factors. Of all devices removed, 30.6% were retrieved from patients who presented with fracture nonunion. Upon microscopic examination, 97% of the retrieved implants exhibited some degree of either surface of interface corrosion. Statistical analysis revealed significant correlations between corrosion scores and the metallurgical properties of grain size and nonmetallic inclusion content. No statistically significant metallurgical or corrosion differences were discerned between the two types of devices studied. However, four implants of the Jewett design and four of the Richards design were found to be out of ASTM specification F-138-76. It should also be noted that four devices of the Jewett design (19%) fractured in situ, while none of the retrieved Richards designs had fractured. No correlation was observed between the plates' corrosion scores and in situ time.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone Plates↗
PubMed1985

Desmoplastic fibroma of the first metatarsal. A case report.

Desmoplastic fibroma is a benign but frequently aggressive tumor of bone. A 27-year-old man was treated for this lesion in the first metatarsal. The lesion recurred, extending into the medial cuneiform necessitating ray resection. The similar clinical and histologic findings of this tumor and other tumors, both benign and malignant, makes familiarity with the character of desmoplastic fibroma essential for proper treatment.

Adult↗
PubMed1985

Biomechanics of running shoe performance.

The running shoe provides shock absorption and motion control for the runner. The change in shock-absorption properties has been studied as a function of miles run. Different models of running shoes encompassing various manufacturers' models and price ranges were mechanically tested to simulate the repeated heel strikes of running. The energy absorbed by the shoes was determined from the area under the load deformation curve at various intervals to the equivalent of having run 500 miles. Shoes were also tested at similar intervals after having been worn by volunteers during normal training. A difference of approximately 33 per cent in the initial shock absorption was observed in the different shoe models tested. In general, the mechanically tested shoes retained approximately 75 per cent of their initial shock absorption capability after 50 miles and approximately 67 per cent after 100 to 150 miles. Between 250 and 500 miles, the shoes retained less than 60 per cent of their initial shock-absorption capacity. The shoes tested after having been worn during running by volunteers had similar but less severe degradation characteristics. These shoes tended to retain approximately 70 per cent of the initial shock absorption characteristics were apparent based upon either shoe price or manufacturer. In addition, shoes that exhibited superior initial shock absorption capability often had more rapid degradation characteristics.

Athletic Injuries↗
PubMed1984

Correlation of tissue reaction to corrosion in osteosynthetic devices.

This study evaluated the interaction of osteosynthetic plates to adjacent tissue. Eleven patients had 13 plates removed with simultaneous biopsies of the adjacent soft tissue. Four patients had pain localized to the area of the plate and 11 patients had routine removal or removal for fracture nonunion. Each plate was graded on a 0-5 point scale for the amount and severity of corrosion present at the screw-plate interface. The adjacent tissue was fixed in formalin and stained with hematoxylin and eosin. The tissue reaction was graded on a 0-5 point scale based on the inflammatory response. A positive correlation of corrosion and tissue reaction was found that was significant at p less than 0.005 in the asymptomatic group. The other good correlation showed that tissue reaction tends to decrease with time at p less than 0.005. There was no correlation of corrosion with tissue reaction in the symptomatic removal group. All patients with pain adjacent to the plates were relieved by implant removal. The findings suggest that stainless steel is minimally toxic to human tissue in most circumstances and that the toxic products are well tolerated. There was a significant group (4/11) that showed a different pattern of tissue response which did not appear to be toxic response. We do not recommend routine implant removal to prevent metal toxicity; however, there is a group of patients who have pain in the area of the implant that may be caused by an allergic reaction and is relieved by implant removal.

Adolescent↗