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Biomedical subjects

R W Mann

Publications and source records attributed to R W Mann.

At least 37 records · Page 2Linked to original sources
PubMed1994

Cartilage stresses in the human hip joint.

The total surface stress measured in vitro on acetabular cartilage when step-loaded by an instrumented hemiprosthesis are partitioned into fluid and cartilage network stresses using a finite element model of the cartilage layer and measurements of the layer consolidation. The finite element model is based on in situ measurements of cartilage geometry and constitutive properties. Unique instrumentation was employed to collect the geometry and constitutive properties and pressure and consolidation data. When loaded, cartilage consolidates and exudes its interstitial fluid through and from its solid network into the inter-articular gap. The finite element solutions include the spatial distributions of fluid and network stresses, the normal flow velocities into the gap, and the contact network stresses at the cartilage surface, all versus time. Even after long-duration application of physiological-level force, fluid pressure supports 90 percent of the load with the cartilage network stresses remaining well below the drained modulus of cartilage. The results support the "weeping" mechanism of joint lubrication proposed by McCutchen.

Anthropometry↗
PubMed1993

Positive identification in a case of intentional extreme fragmentation.

The investigation of the first of the murders of young males to which Jeffrey Dahmer confessed led to systematic survey of two acres of semirural property in Bath Township, Ohio. The survey revealed the fragmentary skeleton of a young adult male, as well as bones of several species of animals. Through archaeobiological analysis, the animal bones were identified and taphonomic modifications documented. The human bones were dry and weathered, and many were rodent-gnawed, indicating that they had been exposed for many years. The human bones displayed an extreme degree of splintering, warping, bending, and spiral breakage. The only relatively complete bone was a cervical vertebra. Dismemberment and breakage had been accomplished by cutting, blunt force, and, in the case of the ribs, manual bending. Even in so extreme a case of intentional fragmentation, however, forensic anthropological analysis resulted in positive identification, with the primary criteria based on matching osteological features evident in premortem and postmortem radiographs of a cervical vertebra.

Adolescent↗
PubMed1993

A method for siding and sequencing human ribs.

Siding and sequencing (that is, putting in anatomical order) human ribs are essential to the proper examination and documentation of injuries to the chest. The paucity of information regarding sequencing nonfleshed human ribs makes it particularly difficult for physical anthropologists and medicolegal authorities to differentiate the midthoracic ribs. It was found that ribs could be accurately sequenced without the aid of a comparative skeleton using such features as maximum (relative) rib length, the size and shape of the articular facets, the distance between the articular facets and rib angle, and the height of the rib heads relative to one another.

Adult↗
PubMed1992

Distal phocomelia of the forearm in a thirteenth-century skeleton from Poland.

The skeleton of a 35- to 40-year-old male (A.D. 1250 to 1300) with distal phocomelia (intercalary transverse) of the right forearm and severe (90-100 degrees) right-sided scoliosis is examined. Congenital malformation of the the right forearm resulted in absence of the radius and ulna, and attachment of the upper arm and hand to the trunk. Lesser abnormalities consist of a-hypoplastic right scapula and misshapened ribs and sternum. This rare deformity reflects the variability and antiquity of congenital malformations of the upper limb.

Adult↗
PubMed1992

Idiopathic bone cavity on the posterior buccal surface of the mandible.

A cavity on the posterior buccal surface of four dry mandibles (n = 8282) is reported. The shape, size, unilaterality, and sex distribution of this phenomenon are similar to anterior and posterior idiopathic bone cavities (i.e., defects) on the lingual cortex. Posterior buccal mandibular defects differ from posterior lingual cavities in their unilateral occurrence and age distribution. The differential diagnosis for posterior buccal mandibular defects includes an anatomic variant, an aneurysmal erosion, erosion by a lymphoid nodule, and a neural neoplasm.

Adult↗
PubMed1992

A protein expressed in the growth cones of embryonic vertebrate neurons defines a new class of intermediate filament protein.

We have isolated and characterized cDNAs that encode a protein expressed in the axons and growth cones of a subset of Xenopus embryonic neurons. The protein is also expressed in a subset of cells of the brain, including cells in even-numbered rhombomeres, the eye, and the heart. The sequence of the cDNA suggests that the protein belongs to a new class of neural-specific intermediate filaments. Both the RNA and the protein are expressed in the neurula and persist during embryogenesis in the brain, cranial nerves, and spinal cord. Because of the predicted structure of the protein, we have named it tanabin (from the Persian word for rope).

Amino Acid Sequence↗
PubMed1992

In vivo acetabular contact pressures during rehabilitation, Part I: Acute phase.

The authors conducted a two-part study to compare in vivo acetabular contact pressures during the acute and postacute phases of rehabilitation. This report compares in vivo acetabular contact pressures generated during selected "inpatient" rehabilitation activities and their relationship to pain, range of motion, and other clinical indicators. A pressure-instrumented Moore-type endoprosthesis was implanted in a 73-year-old woman who had sustained a femoral neck fracture. Acetabular contact pressures during the first 2 weeks after surgery were rank-ordered. Clinical data, including range of motion, manual muscle test grade, use of pain medication, and independence in gait, were collected simultaneously. Acetabular pressures did not follow the predicted rank order corresponding to the commonly prescribed temporal order of inpatient rehabilitation activities. Isometric hip extension and active hip flexion generated the highest pressures of all the studied activities, including those measured during gait activities. Isometric exercises, therefore, may not be entirely benign preparation for ambulatory activity. Clinical data did not correspond with peak pressure data, suggesting that observed responses to rehabilitation may not be dependable criteria for progressing the acute hip rehabilitation protocol. We discuss applications for rehabilitation programs based on hip contact pressure data as an initial attempt to formulate more defensible rehabilitation approaches for patients with acutely painful hips.

Acetabulum↗
PubMed1992

In vivo acetabular contact pressures during rehabilitation, Part II: Postacute phase.

The authors conducted a two-part study to compare in vivo acetabular contact pressures during the acute and postacute phases of rehabilitation in a single subject with a pressure-instrumented femoral prosthesis. This report compares six common hip rehabilitation activities for resultant in vivo hip pressure magnitudes during the first 5 years after discharge from an acute care hospital. These activities were full, partial, touch-down, and non-weight-bearing ambulation and isometric hip abduction and straight-leg-raising exercises. A pressure-instrumented femoral endoprosthesis implanted in a 73-year-old woman who had sustained a femoral neck fracture provided data for the activities. The activities were rank ordered and compared over time according to peak pressure magnitude. Prescribed weight bearing and exercise type were not good predictors of hip peak pressures in this patient. Maximum pressures occurred by 1 year postdischarge for most activities, with a tendency to stabilize or decline thereafter. Resisted isometric hip abduction exercise demonstrated the most variation over time. The results suggest that hip pressures may be limited by controlling muscle force and movement velocity during postoperative hip rehabilitation activities.

Acetabulum↗
PubMed1992

Three-dimensional representations of lingual cortical defects (Stafne's) using silicone impressions.

Lingual cortical defects of the mandible are common radiographic entities found predominantly in adult males. Due to the benign nature of these defects and infrequent need for exploratory surgery, few paleopathologists and clinicians have had the opportunity to examine their contents. The present study, using silicone impressions, provides three-dimensional representations reflecting the size and shape of soft-tissue masses once filling 10 unusually large lingual defects. The 10 specimens were chosen from an international sample of 6,330 dry mandibles, 115 of which had lingual cortical defects.

Adult↗
PubMed1992

Human osteology: key to the sequence of events in a postmortem shooting.

Forensic anthropologic examination of human skeletal remains found when a field was plowed provides evidence of both perimortem trauma, suggesting cause of death, and of subsequent shooting of the disarticulated skeleton. The case exemplifies the application of the specialized skills and knowledge of the physical anthropologist to determination of the postmortem sequence of events.

Adult↗
PubMed1992

Positive personal identity of skeletonized remains using abdominal and pelvic radiographs.

Premortem and postmortem radiographs of the chest and abdomen are often available for comparison and provide a basis for making or rejecting an identification. The case reported here exemplifies the way that individualizing features, such as contours of bony elements, skeletal anomalies, and radiodensities and radiolucencies, are used in establishing personal identity.

Aged↗
PubMed1991

Pressure erosion of the femoral trochlea, patella baja, and altered patellar surfaces.

As knee flexion increases, so do tendofemoral and patellofemoral compression forces. Three cases of long-standing uncorrected flexion contractures of the knees are presented that resulted in marked erosion of the femoral trochlea, patella baja, and remodeled patellar articular surfaces likely reflecting increased angles of flexion. It is probable that the deep femoral grooves are the result of adaptation under high-level persistent contact loads from the quadriceps tendon. These examples expand our knowledge of bone remodeling and offer information of potential use in studying ancient skeletal samples.

Adult↗
PubMed1991

Mechanics of a constrained chair-rise.

A sit-to-stand task is analyzed by a method which estimates the segmental and whole body center of mass (CoM) kinematics and kinetics using bilateral whole body kinematic data from nine healthy young female subjects. The sit-to-stand, or chair-rise, task is constrained with regard to chair height, pace, initial lower limb position and arm use. The chair-rise maneuver is divided into four phases; (1) the flexion momentum phase; (2) the momentum transfer phase; (3) the vertical extension phase; and (4) the stabilization phase; the first three are examined in detail here. The momentum transfer phase, which immediately follows lift-off from the seat of the chair, is the most dynamic portion of the event, demanding a high degree of coordination. This maneuver is analyzed in order to determine if trunk movement is used only to position the body center of gravity or if the trunk motion generates momentum which is important during the brief but critical period of dynamic equilibrium immediately following lift-off from the chair. Our evidence points to the latter case and indicates that inter-segmental momentum transfer is possible during this period.

Adult↗
PubMed1991

Cortical defects in the mandibular sulcus.

Examination of 5366 dry mandibles at the Smithsonian Institution revealed three cases of unilateral lingual defects superior to the mandibular foramen. The differential diagnosis includes a neuroma, neurolemmoma, hemangioma, or aneurysm of the inferior alveolar artery. The clinical significance of a vascular neoplasm or aneurysm would be the likelihood of increasing the risk of injecting the anesthetic solution directly into a blood vessel.

Adult↗
PubMed1991

Exercise and gait effects on in vivo hip contact pressures.

Virtually all hip rehabilitation programs include exercise for muscle force development. The specific effects of various exercise modes on the hip joint itself are unknown. We will report on the effects of common exercise modalities on in vivo hip pressures. Four years prior to data collection, a pressure-instrumented Austin-Moore-type endoprosthesis was implanted in an otherwise healthy 73-year-old woman with a traumatic right hip fracture. Hip pressures during various experimental maneuvers were recorded periodically over a 5-year period. We compared measurements of peak pressure and rate of pressure rise obtained during gait with those obtained during isokinetic, isometric, and isotonic lower-limb exercises. Maximal exercise generated greater peak pressures than did gait, and tripling the angular velocity during exercise roughly tripled the rate of pressure rise. Torque production and resultant in vivo hip pressures varied directly during all experiments. Peak pressures and rate of pressure rise apparently can be controlled by varying the subject's exertion. The results reported are from a single subject; therefore, little generalizability is possible for these data. We suggest, however, that articular pressures may be important to rehabilitation planning; these data provide a direct insight into this potentially important exercise prescription consideration.

Aged↗