Biomedical subjects

H J Hillstrom

Publications and source records attributed to H J Hillstrom.

At least 19 recordsLinked to original sources

PubMed2001

Acceleration of the calcaneus at heel strike in neutrally aligned and pes planus feet.

OBJECTIVE: The purpose of this research was twofold: (1) to study the impulsive acceleration of the calcaneus at heel strike in subjects with neutrally aligned (i.e., normal) feet and (2) to explore how the acceleration may differ in subjects with pes planus (i.e., flat) feet. The component of the acceleration vector aligned with the long axis of the tibia was quantified. DESIGN: Subjects with either foot type were instrumented and calcaneal acceleration was quantified during comfortable cadence locomotion. BACKGROUND: Aberrant peak acceleration has been associated with osteoarthritis. While tibial acceleration has been quantified, calcaneal acceleration has not. Additionally, foot morphology, or foot type, has demonstrated an effect on foot function and thus there may be differences in calcaneal acceleration between foot types. METHODS: Six subjects with neutrally aligned feet and six with pes planus feet were selected via a clinical exam. Accelerometers were attached to the posterior aspect of the medial surface of the calcanei bilaterally and 10 walking trials were collected.Results. The average baseline-to-peak acceleration for the neutrally aligned and pes planus feet was 4.79 g (SD, 2.14 g) and 5.24 g (SD, 3.28 g), respectively; the peak-to-peak acceleration was 5.03 g (SD, 2.74 g) and 6.75 g (SD, 3.89 g). There were no significant differences (P>0.05) between foot types. CONCLUSIONS: The calcaneal acceleration at heel strike for neutrally aligned and pes planus feet was not sensitive to foot type. RELEVANCE: Aberrant acceleration has been associated with the development of osteoarthritis [J. Biomech. 5 (3) (1972) 267; J. Biomech. 6 (1) (1973) 51; J. Biomech. 15 (7) (1982) 487]. Osteoarthritis at the subtalar joint, as well as the ankle and midtarsal joints, may be initiated and/or perpetuated by excessive calcaneal acceleration at heel strike.

Acceleration↗

PubMed2001

Peg-in-hole, end-to-end, and V arthrodesis. A comparison of digital stabilization in fresh cadaveric specimens.

The proximal interphalangeal joint arthrodesis is frequently performed to correct hammer toe deformities. This study was conducted to compare the inherent stability of the three proximal interphalangeal joint arthrodeses--peg-in-hole, end-to-end, and V constructs--in the sagittal plane by means of load-to-failure testing of 30 fresh-frozen cadaveric specimens fixated with a 0.045 Kirschner wire. The peg-in-hole construct was associated with significantly higher peak loads at failure compared with the other two procedures. Furthermore, the peg-in-hole construct had significantly higher stiffness values as compared with the V procedure. This study thus provides evidence that the peg-in-hole procedure is the most biomechanically stable surgical construct for proximal interphalangeal joint fusions under sagittal plane loading.

Arthrodesis↗

PubMed2001

The effect of foot orthoses on standing foot posture and gait of young children with Down syndrome.

The purpose of this study was to determine if foot orthoses (FOs) immediately affected gait of children with Down Syndrome (DS) and excessively pronated feet. Subjects were 3--6 years old; 16 with DS and 10 without disabilities. Gait of children with DS wearing sneakers was compared with and without FOs and compared to gait of children without disabilities. Ankle moment, walking speed during stance phase, sneaker prints, center of pressure, and transverse plane foot angles were collected and compared. In standing, heel eversion was reduced when the children wore FOs (p=0.000). During gait the transverse plane foot angle decreased indicating more internal rotation with FOs (p=0.000). Trial-to-trial variability of pronation-supination index (p=0.0001), foot length contact (p=0.0001), transverse plane foot angle (p=0.0003), and walking speed (p=0.0001) all decreased with FO use. Trial-to-trial variability of normalized peak ankle moment (p=0.0001), and of phase of peak ankle moment (p=0.0001) increased when the children wore FOs.

Child↗

PubMed2000

A case of peroneal neuropathy-induced footdrop. Correlated and compensatory lower-extremity function.

This article reports on the case of a man with peroneal neuropathy-induced footdrop who was seen at the authors' institution 3 years after open reduction and internal fixation of a proximal fibular fracture and a distal, spiral, oblique tibial fracture of the right leg. A comprehensive gait analysis was conducted. A significant footdrop in gait resulted in a "reverse check mark" center-of-pressure pattern, an increased transverse-plane rotation of the foot, and excessive knee and hip flexion in the sagittal plane. These objective findings documented significant dysfunction within the involved lower extremity; in addition, aberrant biomechanics were observed in structures other than the site of initial injury within both limbs.

Adult↗

PubMed1998

Analysis of in vivo 3-D internal kinematics of the joints of the foot.

This paper describes a methodology for the analysis of three-dimensional (3-D) kinematics of live joints of the foot based on tomographic image data acquired via magnetic resonance (MR) imaging. A mechanical jig facilitates acquisition of MR images corresponding to different positions of the joint in a pronation-supination motion. The surfaces of the individual tarsal bones are constructed by segmenting the MR images. A mathematical description of the motion of the individual bones and of their relative motion is derived by computing the rigid transformation required to match the centroids and the principal axes of the surfaces. The mathematically described motion is animated via surface renditions of the bones. The kinematics of the bones are analyzed based on features extracted from the motion description and on how they vary with motion. Based on 17 joints that have been imaged, which includes an abnormal joint and the same joint after surgical correction, we conclude that this methodology offers a practical tool for measuring internal 3-D kinematics of joints in vivo and for characterizing and quantifying with specificity normal kinematics and their pathological deviations. Some of the 3-D kinematic animations generated using the methods of this paper for normal joints can be seen at: http:(/)/www.mipg.upenn.edu.

Biomechanical Phenomena↗

PubMed1998

Bone grafting in foot and ankle surgery. A review of 300 cases.

Three hundred foot and ankle bone grafts were reviewed in three separate series of 100 consecutive grafts from two institutions. The series represent a period from 1977 to 1990 and demonstrate treatment patterns that varied over time and between institutions in indications, graft material, and perioperative management. Over 42% of the 300 grafts were for calcaneal osteotomies; most were Evans calcaneal osteotomies. Over 72% of the grafts were allogeneic bone-bank bone, which performed well in calcaneal osteotomies and for packing of defects. Upon review of the incidence of bone complications, no significant differences were observed between surgical procedures that used autogenous versus allogeneic grafts. However, four out of six failures of first metatarsal repair were with allogeneic bone. There was a significant difference in complication rates for the major indications for bone-graft surgery. Nonunions and arthrodeses resulted in higher complication rates than expected, whereas calcaneal osteotomies resulted in a lower complication rate than expected.

Ankle Joint↗

PubMed1997

Gait analysis and bivalved serial casting of an athlete with shortened gastrocnemius muscles: a single case design.

Muscle tightness may predispose an athlete to injury. Stretching may help prevent injury by increasing joint passive range of motion and perhaps by increasing ankle range of motion during gait. The purpose of this study was to determine if bivalved serial casting and a positioning program would increase the total dynamic ankle range of motion without increasing the amount of compensatory foot pronation used during gait of an athlete with shortened gastrocnemius muscles. The subject was a 21-year-old male athlete. A three-dimensional camera-based kinematic system was used to collect functional dynamic ankle range of motion data. The Musgrave Footprint system was used to determine the relative amount of foot pronation (by measuring the pronation-supination index and dynamic foot angles). Data were collected for baseline, postintervention, and withdrawal phases. Data were then graphed and descriptively interpreted using means, standard deviations, trend, and level analyses. Following the treatment, the subjects showed an increase in mean total dynamic ankle range of motion without an increase in dynamic foot pronation. Eight weeks after treatment, the increase in mean total dynamic ankle range of motion was maintained and the pronation measurement did not change.

Adult↗

PubMed1996

Foot type biomechanics. comparison of planus and rectus foot types.

The basic premise central to the diagnosis and treatment of most mechanogenic foot and ankle pathologies is that a given foot will display a characteristic function depending on the biomechanical alignment of the hindfoot and forefoot. However, the effects of foot type on an individual's ability to perform comfortable cadence locomotion have not been scientifically proven. Therefore, this study was conducted on 21 healthy, young subjects (10 subjects with planus foot type and 11 subjects with rectus foot type) to test whether different foot types yield distinguishable foot functions. New methods were developed to quantify biomechanical foot function during posture and comfortable cadence locomotion. The results of the study indicate that individuals with planus and rectus foot types show statistically significant differences in the biomechanical function of the foot.

Adult↗

PubMed1996

Clinical applications of three-dimensional magnetic resonance image analysis.

A methodology for measuring the kinematic parameters of joints in vivo has been refined using the technique of computerized three-dimensional reconstruction from magnetic resonance images. A research protocol has been developed to establish a classification of normal and pathologic foot function that will have broad clinical application. Development of algorithms for a computer-directed program that can predict resultant kinematics and joint morphometry for a given osteotomy or osseous remodeling procedure will assist the surgeon in preoperative surgical planning.

Ankle↗

PubMed1996

Role of the plantar fascia in digital stabilization. A case report.

The plantar aponeurosis is a ligamentous structure that extends from the calcaneus to the proximal phalanges. Under tension, it functions to support the longitudinal arch, supinate the rearfoot, and stabilize the digits against the ground. The anatomy and biomechanics of the plantar fascia and plantar aponeurosis, particularly their role in digital stabilization, are reviewed. A case is presented showing a patient who developed hammer toes as a postoperative complication after having a portion of the plantar aponeurosis removed.

Fascia↗

PubMed1996

Tailor's bunion. Is fixation necessary?

Tailor's bunion or bunionette are terms that describe a pathologic enlargement occurring laterally on the fifth metatarsophalangeal joint. Regardless of the etiology that precipitates the deformity, the resulting abnormal protrusion of soft tissue or bone can result in pain for the patient. Symptoms can range from mild discomfort to severe, debilitating pain. The patient may present with pain dorsolaterally, laterally, or plantarly. The symptoms are mechanically induced, and are often associated with hyperkeratotic lesions and adventitious bursae. Patients complain most often that they cannot find comfortable shoes. The authors compare the effectiveness of fixated versus nonfixated distal osteotomies of the fifth metatarsal for the correction of tailor's bunion. This study shows that fixation can help control postoperative dorsal displacement of the fifth metatarsal capital fragment (p < 0.0001) and produce less shortening of the metatarsal resulting in fewer complications.

Adolescent↗

PubMed1996

Tarsal tunnel syndrome. A retrospective study.

Many etiologies of tarsal tunnel syndrome exist, but it is difficult to determine the specific etiology for a patient. Surgical success rates vary in the literature from 44% to 100%. This retrospective study reviewed 40 patients with 45 data sets. Thirty-five patients (87.5%) in the study were female; 35 patients (87.5%) were caucasian. Thirty-two feet (71.1%) showed improvement following the tarsal tunnel surgery. The Tinel's sign parameter improvement was statistically significant. The differences in the subjective parameters of burning, radiating, and sharp sensations were statistically significant, while the differences in pins and needle sensation were nearly significant. The Takakura index and its constituent parameters were all statistically significant postoperatively with the exception of muscle atrophy, which did not have sufficient data for testing.

Adult↗

PubMed1994

Objective diagnosis of equinus during gait prior to and following a tibial nerve block.

A quantitative evaluation technique has been developed to assist the clinician in the diagnosis and treatment of ankle equinus deformity. Specifically, the work focuses on accomplishing two major goals: 1) to develop a reliable set of quantitative criteria to assess the degree of dysfunction of the ankle joint during locomotion in patients with equinus deformity; and 2) to determine the effect of various treatment modalities on the ambulatory performance of patients with equinus deformity. A statistically significant difference in two key gait parameters has been demonstrated between healthy subjects and those with equinus deformity.

Adolescent↗

PubMed1993

1993 William J. Stickel Silver Award. Anatomical considerations of the peroneal tubercle.

Gross discrepancy and error regarding the identification and location of the peroneal tubercle have been found in the literature. Furthermore, the authors found no evidence of a repeatable measurement technique in applicable descriptions of this osteologic landmark. In accordance with interrater reliability procedures, the authors established repeatability of peroneal tubercle measurements. In conjunction with the instrumentation's accuracy and resolution, the investigators infer reliability for these measurements. To the best of the authors' knowledge, this study is the only one in which interrater reliability was established for the morphometric assessment of the peroneal tubercle and the retrotrochlear eminence. The results also reestablish the correct anatomical presentation of the retrotrochlear eminence and the peroneal tubercle along the lateral surface of the calcaneus.

Calcaneus↗

PubMed1993

Talonavicular coalition. Objective gait analysis.

Talonavicular coalitions, a rarely reported fusion between the talus and navicular, are often an incidental radiographic finding that may be asymptomatic or associated with peroneal spasm. The authors present a review of literature and case report based on clinical evaluation and instrumented gait analysis. Specifically, a patient presenting with a bilateral talonavicular coalition was objectively evaluated with kinetic, kinematic, muscle dynamometry, and pedobarographic testing to understand the biomechanical limitations related to this pathology. An excessive passive component of ankle torque, a high first metatarsophangeal joint plantar pressure, and a diminished time in the midstance portion of stance phase were measured and compared to those of healthy individuals.

Adolescent↗

PubMed1991

Objective identification of ankle equinus deformity and resulting contracture.

A quantitative diagnostic technique is described for identifying contracture at the ankle joint in patients with equinus deformity, hence addressing the shortcoming of the conventional clinical diagnostic procedure. To gain a better understanding of how contracture contributes to equinus deformity, a study was designed that compared the torque about the ankle joint before and after administering a tibial nerve block to equinus patients and to a control group. Functional equinus, manifested by walking and early heel rise, is defined as inadequate dorsiflexion for normal gait. The ability to accurately identify an equinus condition, and contracture as the contributing factor in equinus deformity, has important implications for the type of treatment prescribed and the evaluation of treatment effectiveness.

Adolescent↗

PubMed1985

Effect of myoelectric signal processing on the relationship between muscle force and processed EMG.

The relationship between the force generated by an isometrically contracting muscle and the associated myoelectric signal has been the subject of extensive investigation in the past and conflicting results were reported regarding this relationship. The objective of the present study was to investigate some of the sources that may lead to such conflicting results. Two possible sources were examined. The first was the variability in the force-EMG relationship resulting from processing the EMG signal with different EMG signal processing techniques and the second was the variability in the force-EMG relation obtained from repeated muscle contractions. The results of the study indicate that slight variations in the force-EMG relationships can be attributed to the selection of different processing techniques. However, the variability in the force-EMG relation, obtained by using different EMG signal processors, was found to be significantly smaller than the variability in this relationship obtained from repeated muscle contractions.

Adult↗

PubMedDate not supplied

Retrospective analysis of neurapraxia and axonotmesis injuries of select peripheral nerves of the foot and ankle and their conservative and surgical treatment (external neurolysis and neurectomy).

There is a paucity of scientific literature that has reviewed the conservative and surgical treatment efficacy for the management of injuries causing neurapraxia and axonotmesis. This retrospective study evaluates the clinical outcomes of certain treatments for these injuries. Twenty-seven patients fulfilled the inclusion/exclusion criteria for the study, and represented both genders and a wide variety of ages, weights, levels of education, and backgrounds. Surgical intervention resulted in a slightly better clinical outcome when compared to conservative therapies. Patients undergoing surgery for a single nerve problem improved more than those who underwent surgery when three or more nerves were involved. Failure was most often associated with: 1) multiple nerve injuries, 2) a previous history of psychopathology, and 3) application of conservative therapy without surgical intervention for single nerve injury.

Administration, Topical↗