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Biomedical subjects

K A Mayo

Publications and source records attributed to K A Mayo.

At least 19 recordsLinked to original sources
PubMed2001

Recommendations for cancer prevention trials using potentially ototoxic test agents.

PURPOSE: Preventive oncology applies pharmacologic agents to reverse, retard, or halt progression of neoplastic cells to invasive malignancy, a process that may require administration of agents over long periods of time. Although ototoxicity may be a tolerable side effect of anticancer or antimicrobial therapy, even modest ototoxicity may not be acceptable in agents developed for preventive oncology that are routinely administered to subjects who neither are, nor necessarily will become, clinically ill. MATERIALS AND METHODS: Age-related shifts in hearing may occur over the course of longterm or open-ended therapy; consequently, age-adjusted norms enable researchers to better distinguish hearing loss caused by drugs from that caused by aging. Norms for hearing sensitivity are derived from the Baltimore Longitudinal Study of Aging and are the basis for the proposed audiologic monitoring recommendations. RESULTS: Audiologic monitoring recommendations are presented that standardize patient selection, adverse event reporting, posttreatment follow-up, and audiologic testing for potentially ototoxic investigational agents. CONCLUSION: These recommendations are applicable to trials of investigational agents as well as various classes of drugs used in routine clinical care.

Adult↗
PubMed1999

The periacetabular osteotomy. Minimum 2 year followup in more than 100 hips.

The results of 123 periacetabular osteotomies in 115 patients were reviewed at an average clinical followup of 4.3 years. The average age of the patients at the time of the operation was 32.9 years. The preoperative diagnosis was congenital dysplasia in 101 hips, Legg-Calve-Perthes disease in 10 hips, Charcot Marie Tooth disease in four hips, epiphyseal dysplasia in three hips, congenital coxa vara in two hips, slipped capital femoral epiphysis in one hip, and posttraumatic and postinfectious dysplasia in one hip each. The ilioinguinal approach was used in 67 hips and the modified Smith-Petersen approach was used in 56 hips. A periacetabular osteotomy was combined with an intertrochanteric osteotomy and/or trochanteric transfer in 32 hips. Ten hips underwent open reduction and internal fixation of an acetabular rim fracture and 18 arthrotomies were performed at the time of periacetabular osteotomy. The average Harris hip score increased from 65 points preoperatively to 89 points at latest followup. The average Merle d'Aubigne score increased from 13.6 points preoperatively to 16.3 points at latest followup. Overall, 83% of the hips were rated clinically as good to excellent. Seven hips have undergone total hip arthroplasty and six subsequent intertrochanteric osteotomies were performed. The majority of the major complications occurred when the osteotomy was performed through the ilioinguinal approach. The latest followup radiographic severity of osteoarthrosis, according to the criteria of Tönnis, improved or was unchanged in 117 hips (95%), and progressed in only six hips (5%). The majority of the hips with preoperative changes in the periarticular bone showed some evidence of regeneration, which was shown by a decrease in the subchondral sclerosis, disappearance of cysts, or healing of an acetabular rim fracture. The short term results of the periacetabular osteotomy are encouraging from the standpoint of improvements in clinical scores and in the appearance of the joint.

Acetabulum↗
PubMed1999

A comparison of different surgical approaches for the periacetabular osteotomy.

The periacetabular osteotomy is a well established surgical procedure for the preventative treatment of degenerative joint disease caused by symptomatic acetabular dysplasia. Surgeons on several continents use varying surgical approaches to achieve the same effective osteotomy. Individual surgical approaches must provide accurate and adequate exposure for the osteotomy and the reorientation of the acetabular fragment. The aim of the surgical approach for such complex and expansive surgery is to minimize morbidity related to the approach. This article compares experiences among three common approaches including the modified Smith-Petersen, ilioinguinal, and direct anterior approaches and describes the double approach.

Acetabulum↗
PubMed1999

Results of periacetabular osteotomy in patients with previous surgery for hip dysplasia.

The results of 19 periacetabular osteotomies in 18 patients who had undergone prior bony surgical procedures for hip dysplasia were evaluated. There were 10 females and eight males with an average age of 30.9 years. Previous surgical interventions included 18 intertrochanteric osteotomies, nine pelvic osteotomies, and two shelf acetabuloplasties. The average clinical followup for this group was 45 months. Harris hip score averages improved from 60 to 90 points. Merle d'Aubigne scores showed similar elevations from 13.1 to 16.4 points. Radiographic assessment documented increased coverage and lower Tönnis secondary arthrosis grades in a significant number of hips. No significant differences in outcome were found between this group and a reference group of patients undergoing periacetabular osteotomy who had no previous hip surgery. These intermediate term results are encouraging and seem to discount anticipated problems of prior scarring and distorted pelvic and proximal femoral anatomy.

Acetabulum↗
PubMed1998

[Avascular femur head necrosis as severe complication after femoral intramedullary nailing in children and adolescents].

Nailing of femoral fractures before closure of the growth plates may lead to avascular necrosis of the femoral head in 3-4% of cases. In addition to the 14 cases described in the literature we present 3 more. Analysis of these cases reveals a common pathogenesis. The nails were all inserted anterograde and were designed for the adult femur. The problem appears to be related to the large diameter of the nail and its entry point in the relatively small femoral neck basis, close to the vessels supplying the femoral head. The role of the open physis remains unclear. Even though the complication of femoral head necrosis is rare, it is a severe complication. Therefore we do not recommend anterograde femoral nailing, using the classic entry point, in children or adolescents. We believe that there is a need for a new design of femoral nail. If both femoral head necrosis and coxa valga are to be avoided, we suggest that the entry point of the nail should be dorsolateral, below the trochanteric physis.

Adolescent↗
PubMed1998

Patients treated for nonunions with plate and screw fixation and adjunctive locking nuts.

Locking nuts were used as an adjunct to plate fixation in 48 procedures in 44 patients. All the procedures were done by one surgeon during a 4-year period. The patients in this study were treated for nonunion or malunion and thus had difficult technical problems, such as cortical defects or holes left from previous hardware. The use of standard implants were generally unreliable for additional fixation. The locking nuts were used as a cortical substitute in 26 instances, to create a fixed angle relationship between the plate and the screw in 14 instances, to elevate the plate off the bone to help increase vascularity in five instances, and to increase purchase in severely osteoporotic bone in three instances. Complete followup was obtained on 43 of the 44 patients. Forty of the 43 patients achieved complete union after their reconstructive procedure. Three patients had continued nonunions with eventual hardware failure and required reoperation. The use of the locking nuts enabled the surgeons to obtain stable fixation at the time of reoperation with eventual union of all of the ununited bones. The success of the use of this implant is best gauged by the fact that the surgeon could place screws effectively where cortical defects existed, allow improved purchase in osteoporotic bone, and create a fixed angle plate screw relationship that would have been difficult to do without the locking nuts.

Adolescent↗
PubMed1998

Displaced fractures of the glenoid fossa. Results of open reduction and internal fixation.

Displaced fractures of the glenoid fossa are an uncommon and anatomically diverse group of injuries. Failure to restore anatomy in these fractures results in poor outcome in most cases. The success of a treatment protocol that encompasses appropriate preoperative imaging, injury pattern assessment, prudent approach choice, and a comprehensive reduction and fixation tactic was evaluated. Twenty-seven patients were assessed clinically and radiographically at a mean followup interval of 43 months from surgery. Anatomic reconstruction was achieved in 24 (89%) patients. Three patients had residual joint incongruities measuring 2 mm or less. The only perioperative complication was a partial superficial wound dehiscence. Two additional patients had infraspinatus palsies of indeterminate origin. Functional rating revealed six (22%) excellent, 16 (60%) good, three (11%) fair, and two (7%) poor outcomes. The fair and poor outcomes largely were related to associated injuries. These findings show that anatomic surgical reconstruction with a low complication rate and good functional outcome can be obtained for most patients with glenoid fossa fractures.

Adolescent↗
PubMed1995

Early results of percutaneous iliosacral screws placed with the patient in the supine position.

The operative management of pelvic ring fractures and dislocations is difficult. Posterior pelvic ring disruptions are often associated with severe soft-tissue injuries and high infection rates. Percutaneous iliosacral screw fixation of the posterior pelvis has become popular with improved fluoroscopic imaging techniques. The percutaneous iliosacral screw technique after closed reduction of the posterior pelvic disruption minimally violates the soft-tissue envelope and should diminish both the operative blood loss and infection rate. The early results and complications are documented in our first 68 patients.

Adolescent↗
PubMed1994

Biomechanical simulation of the anteroposterior compression injury of the pelvis. An understanding of instability and fixation.

Seven fresh cadaveric pelvic specimens were biomechanically analyzed. Testing was first performed on intact pelves and then after progressive disruption of the (1) symphysis pubis, (2) unilateral anterior and interosseous sacroiliac ligaments and capsule, (3) ipsilateral sacrospinous and sacrotuberous ligaments; and fixation with a 4.5-mm narrow dynamic compression plate at the symphysis pubis, or a 4.5-mm narrow dynamic compression plate at the anterior sacroiliac joint with and without the symphysis pubis plate, or a 7.0-mm sacroiliac lag screw anchored into the S1 vertebral body with and without the symphysis pubis plate. Symphyseal gapping occurred after isolated symphysis pubis disruption. With additional disruption of the unilateral sacroiliac joint ligaments, symphysis pubis displacement was unaffected; however, the injured sacroiliac joint gap displacement, and sacroiliac joint flexion angulation on both intact and injured sides increased as compared to the specimen in the intact state. Further disruption of the ipsilateral sacrotuberous and sacrospinous ligament complex produced little additional motion at either symphysis pubis or sacroiliac joints. Plate fixation of the symphysis pubis alone reduced symphysis pubis motion, but not sacroiliac motion. Use of sacroiliac fixation alone without a symphysis pubis plate did not affect symphysis pubis motion. The symphysis pubis plate is the key to stabilizing symphysis pubis motion, and similarly, sacroiliac joint fixation is required to control sacroiliac joint motion. Both single iliosacral screws and plates produced equivalent decreases in sacroiliac joint motion.

Biomechanical Phenomena↗
PubMed1994

Open reduction and internal fixation of fractures of the acetabulum. Results in 163 fractures.

Management of displaced fractures of the acetabulum represents one of the greatest challenges in fracture surgery. This study reports intermediate term results for a single surgeon of 163 fractures in 161 patients treated by open reduction and internal fixation. The mean length of followup was 3.7 years. The most common fracture patterns treated were both column (67), transverse/posterior wall (32), posterior wall (14), and T shaped (12). The surgical approaches chosen were ilioinguinal (86), Kocher-Langenbeck (58), and extended iliofemoral (26) with 7 patients having sequential or simultaneous dual approaches. Reductions were rated by plain radiography and considered anatomic in 93 (56%) and near anatomic (< 2 mm displacement) in 40 (25%). There were 7 (4%) infections, 2 (1%) vascular injuries, 3 (2%) sciatic injuries, and 1 (1%) obturator nerve injury. Overall outcome was rated as excellent in 23 (14%), good in 101 (61%), fair in 25 (16%), and poor in 14 (9%). Nine patients have undergone hip salvage procedures. These results add to the growing body of clinical data which validates open reduction as the treatment of choice in most displaced fractures of the acetabulum.

Acetabulum↗
PubMed1994

Surgical revision of malreduced acetabular fractures.

Early failure of open reduction and internal fixation of fractures of the acetabulum presents a treatment challenge even more difficult than that of the primary injury. This study evaluates the success of reoperation for 64 patients with surgical malreduction or secondary loss of reduction. In 36 patients (56%) the reconstruction achieved was within 2 mm of being anatomic as judged by plain radiography. Overall, 27 patients (42%) had excellent or good outcomes at an average 4.2 year followup. Delay to reoperation appeared to have an adverse affect on the result of surgery. At followup 57% of patients reoperated on within 3 weeks of injury were rated good or excellent. This figure dropped to 29% when the delay exceeded 12 weeks. These data do not compare favorably with results obtained in large series of singly operated fractures; however, they do indicate that it is possible to salvage a significant number of failed open reductions by reoperation.

Acetabulum↗
PubMed1993

Intraarticular fractures of the foot. Talus and lesser tarsals.

In the absence of historical comparative data for the treatment of tarsal fractures, commonly abided maxims of trauma care are noteworthy. A displaced fracture involving an articular surface or a fracture interrupting a mechanical axis is treated by open reduction and internal fixation. Rigid fixation is followed as early as possible with active and passive mobilization. Unlike long bones, whose motion and fracture patterns (i.e., segmental, transverse, and oblique) are understood, the tarsal bones are small bones with complex shapes and restricted motion. As a result, tarsal injuries most often occur with multiple ligamentous and bony injuries. Articular step-off is difficult to establish roentgenographically, the blood supply is tenuous, and fixation is largely dependent on screws and Kirschner wires. Good outcome can be obtained by following principles of internal fixation established in treatment of major joint injuries.

Bone Screws↗
PubMed1992

Immediate internal fixation of open, complex tibial plateau fractures: treatment by a standard protocol.

A retrospective review of 46 consecutive patients with complex (Schatzker V and VI) tibial plateau fractures treated at Harborview Medical Center between 1984 and 1989, disclosed a subset of 14 grade II or III (Gustilo) open injuries. We wished to determine the incidence of infection, union rate, and the number of operations required to achieve a satisfactory result, based on a treatment protocol: alignment and splinting of fracture at the scene of injury if possible, antibiotics administered in the emergency room (ER) and continued for 48 h, and admission of patient to the operating room as quickly as possible for irrigation and thorough debridement of the wound, immediate rigid internal fixation, and delayed primary closure at 5 days. No acute deep infection or radiographic evidence of implant loosening was noted. The final outcome was graded by Hospital for Special Surgery (HSS) Knee Rating Score at an average follow-up of 2 years 7 months. Radiographs were reviewed for reduction and evidence of postoperative change in reduction. The average HSS Functional Score was 81.5, and Knee Score was 84.6. Of 14 limbs, 10 had an excellent radiographic grade that did not change at follow-up, 2 had a satisfactory grade, and 2 had a poor grade.

Abbreviated Injury Scale↗
PubMed1991

Ankle arthrodesis using internal screw fixation.

Ankle arthrodesis treated by external fixation frequently results in complications from pin tract infections, loss of position, nonunion, and malunion. A method of ankle arthrodesis using 6.5-mm cancellous screws as the primary fixation hardware was developed. The most important screw is placed from the posterior malleolus into the neck and head of the talus, and medial and lateral malleolar screws are added to secure fixation. Near-normal anatomy is maintained with this technique because little or no bone, only cartilage, is removed. Earlier cases were all done through an anterior approach. Later, special techniques were developed for placing screws and strain-relieving bone grafting was added to promote union. Twenty-three cases that were treated by the earlier technique are reviewed. The overall fusion rate was 74%. Three conditions (avascular talus, pyarthrosis, and spasticity) were identified that placed patients at high risk for failure of fusion. Of the patients who were not in a high-risk group, only one had a delayed union. When the high-risk patients were not included in the statistics, the fusion rate was 93%. The evolved technique shows great promise for accurate and trouble-free ankle arthrodesis.

Adult↗
PubMed1990

Results in patients with craniocerebral trauma and an operatively managed acetabular fracture.

Results in 23 patients with significant craniocerebral trauma (Glasgow Coma Scale less than or equal to 10) and displaced acetabular fracture requiring surgery were reviewed after a minimum follow-up of 1 year. Despite a postoperative anatomic reduction in all but one case, clinical outcome for these hips was poor, with an average Harris hip rating of 59. Patients older than 40 years had a significantly poorer outcome than did younger patients (p = 0.004). Postoperative problems occurred in 70% of patients (n = 16); the largest portion of these represented symptomatic heterotopic bone, which occurred in 61%. None of the four patients who had an anterior ilioinguinal surgical approach had symptomatic heterotopic ossification. The average Glasgow outcome score was 3.9 out of 5, and 20 of the 23 patients, despite a prolonged convalescence, were able to return to independence and self-care. The authors conclude that patients with combined significant craniocerebral trauma and an operatively managed displaced acetabular fracture are likely to have compromised hip function despite a well-executed osteosynthesis. This was especially true for those patients over age 40 in this series. The authors suggest that if the fracture pattern permits it, the operative management of the acetabular fracture in these patients be by an anterior ilioinguinal approach, so as to minimize the formation of heterotopic bone.

Acetabulum↗
PubMed1990

Treatment of tibial malunions and nonunions with reamed intramedullary nails.

Reamed intramedullary nailing is an effective, relatively low-risk technique for the management of delayed union, nonunion, and malunion of the tibia. Closed technique should be used where possible and open realignment, when necessary, should be executed with minimal dissection. Bone grafting is rarely indicated. The use of interlocking nails provides an added degree of security in the control of rotation.

Adult↗
PubMed1989

asgB, a gene required early for developmental signalling, aggregation, and sporulation of Myxococcus xanthus.

The asgB genetic locus of Myxococcus xanthus specifies a function which is required early in the developmental pathway leading to aggregation and sporulation in fruiting bodies. The developmental defect of asgB mutants can be compensated by extracellular complementation using either intact wild-type cells or cell-free supernatants conditioned by developing wild-type cells. A Tn5 insertion was isolated closely linked to asgB480 and facilitated the cloning of both the wild-type (asgB+) and the mutant (asgB480) alleles in Escherichia coli plasmid. Tandem duplications of the asgB locus were constructed in M. xanthus; the completely wild-type phenotype of asgB+/asgB480 partial diploids implies that the asgB480 allele is recessive. This finding, along with extracellular complementation by wild-type cells, is consistent with the hypothesis that the asgB+ locus is required to produce a substance with an intercellular signalling function. At least part of the asgB gene was found to lie within a 1.2 kb SmaI DNA fragment. This 1.2 kb fragment, as well as smaller fragments derived from it, were used as DNA probes in RNA/DNA hybrid analyses of transcription in the asgB region. Two small mRNA species were detected, one about 650 bp long, and the other about 500 bp; the two species of mRNAs apparently overlap. Both mRNAs are present in low, but approximately equal amounts, in vegetatively growing cells. This is consistent with the observation that asg mutants display a mutant vegetative phenotype (a change in colony color and spreading behavior) as well as defective development.

Blotting, Northern↗