Search PubMed⌕ Search

Biomedical subjects

R B Anderson

Publications and source records attributed to R B Anderson.

At least 37 records · Page 2Linked to original sources
PubMed1999

Dorsiflexion metatarsal osteotomy for treatment of recalcitrant diabetic neuropathic ulcers.

Twenty diabetic patients underwent 22 dorsiflexion metatarsal osteotomies for treatment of chronic persistent or recurrent neuropathic forefoot ulcers. Mean duration of nonoperative treatment was 13 months. The procedure consisted of irrigation and debridement of the ulcer followed by basilar closing wedge metatarsal osteotomy performed through a dorsal approach. At follow-up, complete ulcer healing was noted in 21 cases (95%) at an average of 40 days postoperatively. Complications occurred in 15 cases (68%). The main problems encountered postoperatively were acute Charcot disease (32%) and deep wound infections (14%). Transfer lesions under adjacent metatarsal heads developed in two cases (9%). One ulcer (5%) failed to heal secondary to vascular insufficiency and eventually required a below the knee amputation after a failed revascularization attempt. Loss of screw fixation occurred in one patient (5%) but acceptable metatarsal alignment was maintained and the ulcer healed uneventfully. There were no cases of ulcer recurrence. The results of this study suggest that dorsiflexion metatarsal osteotomy is a reliable salvage procedure for the treatment of recalcitrant neuropathic forefoot ulcers that have failed an adequate trial of nonoperative treatment. This procedure is associated with a high complication rate, as would be expected in this patient population.

Adult↗
PubMed1999

Intermediate to long-term follow-up of medial-approach dorsal cheilectomy for hallux rigidus.

Dorsal cheilectomy of the hallux metatarsophalangeal (MTP) joint through a medial approach can effectively provide long-term relief of pain and improve function in symptomatic mild-to-moderate hallux rigidus, despite progression of generalized first MTP joint arthritic degeneration and/or loss of motion. Fifty-seven patients (75 feet) with arthritis of the first MTP joint underwent dorsal cheilectomy through a medial approach for hallux rigidus failing nonoperative management. Excision of the dorsal articular surface of the first metatarsal head and dorsal osteophytes was performed through a medial approach that also allowed for plantar capsular release and removal of lateral osteophytes. Minimum follow-up was 3 years (average, 63 months; range, 37-92 months). Fifty-two patients (68 feet) returned for clinical and radiographic evaluation. American Orthopaedic Foot and Ankle Society Hallux Rating scores improved from a preoperative average of 45 to 85 points at follow-up. Average dorsiflexion improved from 19 degrees to 39 degrees, and the average range of motion improved from 34 degrees to 64 degrees. Preoperative radiographic grade of arthritic degeneration was grade I in 17 feet, grade II in 39 feet, and grade III in 12 feet; at follow-up, the radiographic grade was grade I in 2 feet, grade II in 26 feet, and grade III in 40 feet. Thirty-two feet worsened one grade, 6 feet worsened two grades, and 28 feet demonstrated no change (12 of 28 were grade III, preoperatively). A dorsal spur recurred in 21 feet, 9 of which were symptomatic. Complications included two superficial wound infections and four transient paresthesias of the hallux, all of which resolved uneventfully.

Adult↗
PubMed1999

Clinical evaluation of the modified Brostrom-Evans procedure to restore ankle stability.

The modified Brostrom procedure has become the standard for anatomic repair of symptomatic chronic lateral instability. However, it was our perception that this local tissue repair may fail eventually, particularly in patients that are overweight, hyperflexible, or are involved in strenuous work or athletic activity. This is a retrospective review of 21 lateral ankle reconstructions (20 patients) in which the modified Brostrom technique was augmented with a portion of the peroneus brevis tendon. All patients were interviewed at an average of 29.5 months (range, 14-56 months postsurgery). Fourteen patients also agreed to be evaluated by a physical therapist. No surgical complications were identified. American Orthopaedic Foot and Ankle Society ankle-hindfoot scores averaged 98.2. There was no significant difference in passive or active range of motion of plantarflexion or dorsiflexion when compared to the contralateral ankle. However, a statistically significant loss of inversion (passive, P = 0.011; active, P = 0.018) and eversion (passive, P = 0.004; active, P = 0.007) was noted when compared to the contralateral ankle. Measurement of isometric eversion strength, using a Cybex 340 Isokinetic device, and functional testing, using a lateral lunge test, revealed no significant loss of peroneal strength. The authors conclude that chronic lateral ankle instability in the general population can be successfully managed with a modified Brostrom procedure augmented with a portion of the peroneus brevis. The procedure remains technically simple and provides a greater static restraint for inversion stress without evidence of dramatic overtightening or loss of peroneal strength.

Adult↗
PubMed1999

Novel guidance cues during neuronal pathfinding in the early scaffold of axon tracts in the rostral brain.

A scaffold of axons consisting of a pair of longitudinal tracts and several commissures is established during early development of the vertebrate brain. We report here that NOC-2, a cell surface carbohydrate, is selectively expressed by a subpopulation of growing axons in this scaffold in Xenopus. NOC-2 is present on two glycoproteins, one of which is a novel glycoform of the neural cell adhesion molecule N-CAM. When the function of NOC-2 was perturbed using either soluble carbohydrates or anti-NOC-2 antibodies, axons expressing NOC-2 exhibited aberrant growth at specific points in their pathway. NOC-2 is the first-identified axon guidance molecule essential for development of the axon scaffold in the embryonic vertebrate brain.

Animals↗
PubMed1998

Chondroitin sulfates modulate axon guidance in embryonic Xenopus brain.

Chondroitin sulfate proteoglycans display both inhibitory and stimulatory effects on cell adhesion and neurite outgrowth in vitro. The functional activity of these proteoglycans appears to be context specific and dependent on the presence of different chondroitin sulfate-binding molecules. Little is known about the role of chondroitin sulfate proteoglycans in the growth and guidance of axons in vivo. To address this question, we examined the effects of exogenous soluble chondroitin sulfates on the growth and guidance of axons arising from a subpopulation of neurons in the vertebrate brain which express NOC-2, a novel glycoform of the neural cell adhesion molecule N-CAM. Intact brains of stage 28 Xenopus embryos were unilaterally exposed to medium containing soluble exogenous chondroitin sulfates. When exposed to chondroitin sulfate, NOC-2(+) axons within the tract of the postoptic commissure failed to follow their normal trajectory across the ventral midline via the ventral commissure in the midbrain. Instead, these axons either stalled or grew into the dorsal midbrain or continued growing longitudinally within the ventral longitudinal tract. These findings suggest that chondroitin sulfate proteoglycans indirectly modulate the growth and guidance of a subpopulation of forebrain axons by regulating either matrix-bound or cell surface cues at specific choice points within the developing vertebrate brain.

Animals↗
PubMed1997

Inhibitory consequences of memory selection.

When subjects select a prime from a visual display while leaving a distractor prime unselected, response time (RT) or response accuracy to a subsequent probe may be impeded if the distractor prime and probe are identical, or if they are related to one another. This phenomenon, negative priming (NP), has obvious implications for understanding perceptual selection. However, it is not known whether NP results from other kinds of selection processes. The present studies were designed to investigate whether NP occurs when primes are selected from working memory rather than from a visual display. In the two experiments, the subjects memorized two primes, selected one prime for further processing, and classified the contents of a probe display. Significant NP occurred in both Experiments. In Experiment 2, however, NP occurred only under easy-selection conditions; the effect was reversed under difficult-selection conditions. The findings indicate a role for NP in memory processing, but contrast with the results from perceptual selection studies showing greater NP under difficult-selection than under easy-selection conditions. The present finding suggests a complex and perhaps strategy-dependent relationship between memory selection difficulty and NP.

Analysis of Variance↗
PubMed1997

Autogenous bone grafting of hallux sesamoid nonunions.

We first performed autogenous bone grafting for lesions of the hallux sesamoid in 1984. During the next 9 years, 21 patients (11 men and 10 women with an average age of 34 and 32 years, respectively) underwent this surgical procedure for symptomatic tibial hallux sesamoid non-unions. Successful bony union was achieved in all but two patients. The majority of patients obtained concomitant relief of preoperative symptomatology and returned to their preinjury level of activity. We believe that this procedure serves as an alternative to hallux sesamoid excision in selected cases.

Adult↗
PubMed1997

Artifactual power curves in forgetting.

Recent studies of the mathematical relationship between time and forgetting suggest that it is a power function rather than an exponential function, a finding that has important theoretical consequences. Through computational analysis and reanalyses of published data, we demonstrate that arithmetic averaging of exponential curves can produce an artifactual power curve, particularly when there are large and systematic differences among the slopes of the component curves. A series of simulations showed that the amount of power artifact is small when the slopes of the component curves are normally or rectangularly distributed and when the performance measure is noise free. However, the simulations also showed that the artifact can be quite large, depending on the shape of the noise distribution and restrictions in the performance range. We conclude that claims concerning the form of memory functions should consider whether the data are likely to contain artifact caused by averaging or by the presence of range-restricted noise.

Artifacts↗
PubMed1997

Need probability affects retention: a direct demonstration.

Recent memory theory has emphasized the concept of need probability--that is, the probability that a given piece of learned information will be tested at some point in the future. It has been proposed that, in real-world situations, need probability declines over time and that the memory-loss rate is calibrated to match the progressive reduction in need probability (J.R. Anderson & Schooler, 1991). The present experiments were designed to examine the influence of the slope of the need-probability curve on the slope of the retention curve. On each of several trials, subjects memorized a list of digits, then retained the digits in memory for 1, 2, 4, 8, or 16 sec. Some trials ended with a recall test; other trials ended with the message, "no test." In Experiment 1, the likelihood of encountering a memory test (i.e., the need probability) was made to either increase or decrease as the retention interval increased; in Experiment 2, need probability either was flat (invariant across retention intervals) or decreased as the retention interval increased. The results indicated that the shape of the need-probability curve influenced the slope of the retention curve (Experiment 1) and that the effect became larger as the experimental session progressed (Experiment 2). The findings support the notion that memory adapts to need probabilities and that the rate of forgetting is influenced by the slope of the need-probability curve. In addition, all of the forgetting curves approximated a power function, suggesting that need probability influences the slope but not the form of forgetting.

Educational Measurement↗
PubMed1996

Expression of a novel N-CAM glycoform (NOC-1) on axon tracts in embryonic Xenopus brain.

The aim of the present study was to characterise the expression pattern of a novel N-CAM glycoform, called NOC-1, within axon tracts of the developing Xenopus brain. Double-label immunostaining of wholemount embryonic brains revealed that only a subpopulation of axons express NOC-1. Axons in the supra-optic tract (SOT) express NOC-1 and course ventrally from the presumptive telencephalon to join the tract of the post-optic commissure (TPOC), the principal longitudinal tract of the forebrain. NOC-1 was also expressed by axons that form discrete fascicles in the ventral portion of the TPOC. Growth cones in the SOT appeared to only turn caudally upon contacting the NOC-1 expressing axons in the ventral region of the TPOC. Thus, all NOC-1 expressing axons within the TPOC follow a common ventral pathway. These observations demonstrate that there is selective partitioning of axons which express a novel N-CAM glycoform within the developing Xenopus forebrain. Moreover, these results indicate that the SOT-TPOC junction is an important choice point for ventrally growing SOT axons and that selective interactions occur between subpopulations of axons expressing NOC-1 in the SOT and TPOC.

Animals↗
PubMed1996

Prospective, randomized comparison of proximal crescentic and proximal chevron osteotomies for correction of hallux valgus deformity.

In this study, intermetatarsal angle (IMA) correction, functional outcome, and healing time for the proximal crescentic and proximal chevron osteotomies in moderate to severe hallux valgus deformity were prospectively compared. Seventy-five patients (97 feet) were prospectively randomized to either a proximal crescentic or proximal chevron osteotomy for the correction of moderate to severe hallux valgus deformity with associated metatarsus primus varus. Criteria for study entry included age (adult patients), IMA greater than or equal to 13 degrees, persistent symptoms despite nonoperative treatment, and minimum follow-up of 12 months. Twenty-nine patients (41 feet) in the crescentic group and 37 patients (43 feet) in the chevron group returned for follow-up at an average of 24 and 20 months, respectively. Good results were achieved with both procedures. No statistically significant differences were found with respect to correction of the IMA or to functional outcome between the two groups. Results held true irrespective of patient age, severity of disease, or bilateral involvement. A statistically significant shorter healing time of the first metatarsal was found after proximal chevron osteotomy. Other potential benefits of the chevron procedure included avoidance of dorsiflexion of the first metatarsal, tendency toward less shortening of the first metatarsal, and more medial distribution of tibial sesamoids following surgery, all of which may reduce the potential for development or persistence of transfer lesions.

Adult↗
PubMed1996

Distal soft tissue release using direct and indirect approaches: an anatomic study.

Two surgical approaches for distal soft tissue release in the correction of hallux valgus, one using a dorsal first web space incision and the other a longitudinal medial capsulotomy incision (used also for medial eminence resection), were studied to compare and delineate the structures actually incised. Anatomic dissections were performed on six fresh-frozen amputation specimens using each of the approaches. The adequacy of release of the adductor hallucis, transverse and oblique heads, first metatarsophalangeal lateral capsule, and suspensory ligament was reviewed. Any inadvertent damage to the first metatarsal head cartilage, second metatarsophalangeal capsule, and lateral head of the flexor hallucis brevis tendon was also noted. Distal soft tissue release is thought to be an important part of hallux valgus surgery. Based on our anatomic dissections, the actual extent of the release may be inconsistent and unpredictable, and may have implications for the predictability of results after hallux valgus surgery.

Cadaver↗
PubMed1996

Success of calcaneonavicular coalition resection in the adult population.

Twelve adult patients (13 feet), average age 33 years (range, 19-48 years), with calcaneonavicular coalitions remained symptomatic after a trial of conservative treatment. Surgical resections were performed. Before surgery, there was < 5 degrees of inversion/eversion in 11 patients, radiographic evidence of degenerative arthritis in 10 feet (77%), and talar beaking in 7 feet. At an average postoperative follow-up of 36 months, subjective relief of preoperative symptoms was achieved in all but two patients. Two patients required subsequent hindfoot arthrodesis. Resection of calcaneonavicular coalition in the adult can be successful and provides an option to arthrodesis after nonoperative methods have failed.

Adult↗
PubMed1996

A review of the quality-of-life aspects of urinary urge incontinence.

Urinary incontinence (UI) is prevalent and costly, occurring in 15 to 30% of the US population over the age of 60 years. Among people aged 15 to 64 years, UI occurs in 1.5 to 5% of men and 10 to 25% of women. Severe incontinence occurs in 6% of the general US population, and it is estimated that $US10 billion per year is spent in direct costs alone on care for these patients. This review presents a description of the various types of UI and describes the prevalence and costs of the condition. In addition, 3 approaches to assessing the impact of UI on quality of life are discussed, namely generic measures, disease-specific measures and qualitative approaches. We also review papers on UI and sexual functioning, UI in men, and some aspects of treatment. The review was conducted in the process of developing a new disease-specific measure for urinary urge incontinence (UUI). In general, the literature suggests that UUI has a greater impact than stress incontinence on quality of life, and that UI affects social and psychological functioning more than physical functioning. Only in a minority of individuals is the impact of UI disabling; however, most individuals with UI show significant reduction in their social functioning. Several studies suggest that the impact of UI is not solely a function of its severity, but also depends on individual coping abilities. Some studies also indicate that the social problems associated with UI grow with time, but it is not clear if that is a function of increasing severity of the condition, or the particular adaptations required for coping with this problem. An important distinction appears to be the ability of individuals to avoid public notice of their condition because of uncontrolled accidents. In summary, there is a need for a new measure of the quality-of-life impact of UUI that is based on the literature and on in-depth interviews with patients.

Aged↗