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The insertion, finishing, and polishing of ceramic restorations can be arduous even for the most skilled operator. Attention to details as described above and refinement of all steps can lead to clinical success (Fig. 8-12). At this time composite and ceramic margins cannot equal those of cast or direct gold but with care and patience, clinically adequate results can be achieved.
Measurement of misfit at the implant-prosthesis interface is a difficult procedure. One factor common to all methods that attempt to measure 3-dimensional distortion to the micron level is the difficulty in providing verifiably consistent reference points between individual measurement sets. Consequently, the majority of studies use a relative distortion model in which the coordinate reference system is integral to the framework, thus limiting the value of the data gathered. In the method described, the datum plane and the coordinate reference system were set up external to the framework and could be re-established between measurement sets in a verifiable manner.
Force loading of dental prosthesis is generally a guessing game played by the operator with the patient. Relying on a patient is comfort level to adjust occlusion is now being replaced by sound force information provided by the T Scan II. Proper use of the T Scan II when installing a segmental fixed prosthesis gives a more precise, comprehensive occlusion. Porcelain surfaces, solder joints, and the underlying abutment teeth can now be loaded with low-to-moderate forces because the operator can fine-tune the occlusal forces precisely. With proper force loading, greater material and prosthesis longevity is significantly enhanced.
Fifty subjects with mild to moderate-severe sensorineural hearing loss and prior experience with binaural amplification were evaluated at two sites (25 subjects at each site). Signal-to-noise ratios (SNRs) were measured using the Hearing in Noise Test (HINT) after each subject wore binaural in-the-ear hearing aids programmed for omnidirectional and dual-microphone performance, for 4 weeks. Both microphone conditions were evaluated under "ideal" (signal at 0 degrees; noise at 180 degrees) and "diffuse" (signal at 0 degrees; correlated noise at 45 , 135 degrees, 225 degrees, and 315 degrees) listening conditions. Results revealed statistically significant mean improvements in SNRs between 3.7 and 3.5 dB at Site I and 3.2 and 2.7 dB at Site II for the ideal and diffuse listening conditions, respectively, for the dual-microphones in comparison to the performance provided by the omnidirectional microphone.
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Patients who have undergone enucleation of the eye can be treated with glass eye prostheses, provided retention is adequate. Inadequate retention due to contraction of the conjunctival mucosa is a common problem which frequently affects the lower fornix first. This can be corrected using a free full-thickness buccal mucosa graft. Indications, operative procedures and postoperative results are presented.
Differences in pelvic obliquity between small groups of persons with unilateral lower limb amputation and subjects without amputation were analyzed. Kinematic walking data were collected as six males with transtibial amputation and three males with transfemoral amputation walked over a range of speeds. The pelvic obliquity patterns and amplitudes from the groups with amputation were compared to normal data. Results showed that smaller peak-to-peak amplitudes of pelvic obliquity were associated with higher amputation levels. Pelvic drop during early prosthetic-limb stance tended to be smaller than during early sound-limb stance. Most of the subjects with amputation exhibited an obliquity pattern in which the hip on the prosthetic side was raised above the stance-side hip during prosthetic swing phase, indicative of a compensatory action known as hip-hiking. The subjects with transfemoral amputation exhibited this hip-hiking pattern during sound-limb swing phase as well. Results from this study suggest that further investigation is required to determine those limitations of current prosthetic technology that adversely affect pelvic obliquity in the gait of persons with amputation, and to determine if significant benefit can be realized by restoring a normal pattern of pelvic obliquity to the gait of persons with amputation.
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BACKGROUND AND AIM OF THE STUDY: The study aim was to evaluate the hemodynamic function after aortic valve replacement (AVR) using the On-X valve, in comparison with St. Jude Medical (SJM) HP bileaflet valves. METHODS: Patients received either the On-X (n = 20) or SJM HP prosthesis (n = 20) for AVR. The control (SJM HP) group was computer-matched with the On-X group for age, gender, aortic stenosis as underlying disease, body surface area, NYHA functional class, left ventricular size, mass and function, transvalvular pressure gradients and cardiac index. Mean implanted valve size was 23.5 mm (three 21 mm, ten 23 mm, six 25 mm, one 27 mm) in both groups. All patients underwent postoperative, and six- and 12-month follow up echocardiography. RESULTS: The intra- and postoperative course was uneventful in all patients. There were no significant differences in cross-clamp and cardiopulmonary bypass times, intensive care unit stay, in-hospital stay and postoperative NYHA functional class. Two patients (both On-X) had paravalvular leakage postoperatively and at follow up. Five patients in the control group had additional myocardial revascularization. Transvalvular flow velocities were 2.38 +/- 0.3 versus 2.38 +/- 0.4 m/s (p = NS) postoperatively, and 2.08 +/- 0.2 versus 2.22 +/- 0.3 m/s (p = NS) at one year follow up for On-X and SJM HP valves, respectively. Maximum pressure gradients were 16.9 +/- 6.0 versus 18.5 +/- 8.0 mmHg (p = NS) postoperatively and 14.0 +/- 3.7 versus 16.5 +/- 5.7 mmHg (p = NS) at one year for the two valve types, respectively. A relatively pronounced transvalvular reflux was diagnosed for On-X valves. CONCLUSION: At one year after implantation, the On-X bileaflet prosthesis is equally suited for AVR in comparison with the 'standard' therapy (SJM HP). Exact sizing requires some experience. There were no significant differences between the two prostheses with regard to hemodynamic parameters either postoperatively or at one-year follow up. Long-term prospective randomized studies yet have to be carried out.
This paper presents the design of a body-powered voluntary closing prosthetic hand. It is argued that the movement of the fingers before establishing a grip is much less relevant for good control of the object held than the distribution of forces once the object has been contacted. Based on this notion, the configurations of forces on the fingers and the force transmission through the whole mechanism were taken as a point of departure for the design, rather than movement characteristics. For a good distribution of pinching forces on the object and a natural behavior, the prosthesis is made adaptive and flexible. To achieve good force feedback, the disturbing influences of the cosmetic glove are strongly reduced by a compensation mechanism. To further improve the transmission of forces, friction is reduced by furnishing the whole mechanism with rolling links. This force-directed design approach has led to a simple mechanism with low operating force and good feedback of the pinching force.
New techniques of evaluation, risk identification, wound product application, and infection control allow limb preservation to be an extremely viable option for the neuropathic and diabetic population. The orthotist specializing in wound care brings off-loading techniques to the clinical setting to allow immediate reduction of pressure to the wound site. By reducing external forces, the ulceration responds to wound care products efficiently, and closure times decrease with optimal outcomes. Following closure, the foot must be accommodated to prevent further breakdown, and regular patient follow-up should be consistent with their risk identification.
Postoperative management of lower extremity amputation continues to evolve with advances in prosthetic technology, surgical technique, and rehabilitation considerations. Almost 50 years ago, the first immediate postoperative prosthesis was conceived, and has been used since with varying degrees of success. More recently, use of the removable rigid dressing combined with aggressive physical therapy has been found to be a safe and cost-effective method of treatment for the new amputee.
The transfemoral socket is the interface between the patient's residual limb and the remaining prosthesis. Whether the patient uses a technologically advanced knee mechanism and foot or a single axis, constant friction knee and solid ankle cushioned heel, no other prosthetic component is as crucial in assuring a comfortable and well-functioning prosthesis as the socket. This article discusses the rationale of quadrilateral and ischial containment socket designs and reviews suspension options.
The purpose of this article is to provide a framework for evaluating the features of a knee. A single knee unit has a combination of several control features. As is expected, new units are introduced with improvements to certain features. Prosthetic knee selection generally is based on the patient's ability. An inappropriate knee selection (or improper adjustment) may leave the patient apprehensive and fearful that the knee might buckle with each step. An appropriate selection of a properly adjusted knee unit closely matches the functional ability of the patient and yields a smooth, reliable gait.
This paper describes a device that allows the imaging of prosthetic legs under load conditions using spiral computerized tomography (CT). The device consists of a chair and a vertical footplate mounted on a 17.8 x 1.9 cm oak board that is 197 cm long. The load device can be easily positioned onto the CT bed. A subject sits in the chair and applies force by pushing the foot portion of the prosthesis against the footplate. The magnitude of the force is monitored by a digital force gauge coupled to the footplate. Because the load is borne by the hips and lower back of the subject against the chair, substantial forces can be generated and steadily maintained for the 20-45 s duration of the CT study. This device has been used successfully with 19 transtibial amputees, allowing the acquisition of spiral CT studies with half and full body weight loads.
OBJECTIVE: To describe our experience with the retrosigmoid-transmeatal (RS-TM) approach in auditory brainstem implantation (ABI) as well as the anatomosurgical guidelines for this route. STUDY DESIGN: Retrospective case review. SETTING: Ear, Nose, and Throat Department of the University of Verona. PATIENTS: Five patients with neurofibromatosis type 2 (NF2) were operated on for vestibular schwannoma removal with ABI implantation from April 1997 to June 1999. The patients were four men and one woman, whose ages ranged from 22 to 37 years. The tumor sizes ranged from 12 to 30 mm. The records of a total of 179 patients operated on for vestibular schwannoma (VS) removal via the RS-TM approach from January 1990 to June 1999 were also evaluated. Their ages ranged from 18 to 88 years (average 54 years). The tumor sizes ranged from 4 to 50 mm. Five patients had a solitary VS in the only hearing ear. INTERVENTION: The classic RS-TM approach was used in all patients. After tumor excision, for ABI implantation, the landmarks (seventh, eighth, and ninth cranial nerves, choroid plexus) for the foramen of Luschka were carefully identified. The choroid plexus was then partially removed, and the tela choroidea was divided and bent back. The floor of the lateral recess of the fourth ventricle and the convolution of the dorsal cochlear nucleus became visible. The electrode array was then inserted into the lateral recess and correctly positioned with the aid of electrically evoked auditory brainstem responses (EABRs). MAIN OUTCOME MEASURES: Intraoperative EABR and postoperative speech perception evaluation. RESULTS: Auditory sensations were induced in all patients with various numbers of electrodes. Different pitch sensations could be identified with different electrode stimulation. CONCLUSIONS: In the authors' experience, the RS-TM approach is the route of choice for patients who are candidates for ABI when there is a chance of hearing preservation during surgery. If auditory function is lost during surgery, anatomical preservation of the cochlear nerve may allow hearing restoration with a cochlear implant. Direct intraoperative recording of cochlear nerve action potentials (CNAPs) and round window electrical stimulation are mandatory for these purposes. In addition, decompression of the intrameatal portion of the vestibular schwannoma and planned partial tumor resection with hearing preservation are also possible with the RS-TM approach.
Three patients with neurofibromatosis type 2 who had undergone previous cochlear nerve tumour removal were implanted with the Nucleus 21-channel auditory brainstem implant (ABI). The time intervals between tumour removal and implantation were 4, 5, and 7 years, respectively. Total bilateral deafness was confirmed before implantation. One patient was also blind after acute intracranial hypertension. The translabyrinthine approach was used in all cases. The choice of side for implantation depended on pre-operative magnetic resonance imaging study, the facial nerve function, the presence of recurrent and/or other lesions, and the patient's preference. Although the scarring of prior surgical procedure largely changed the anatomical structures in the cerebello-pontine angle, various landmarks could be found to locate the foramen of Luschka, where the ABI electrode was inserted into the lateral recess of the fourth ventricle. During surgery, the electrically evoked auditory brainstem responses were recorded to confirm that the ABI stimulation activated the auditory system; the electromyogram of the 7th and 9th nerves was helpful in finding the landmarks and minimising the triggering of the cranial nerves with ABI stimulation. The number of active electrodes was 21, 7, and 4 in the three patients. All obtained meaningful pitch scaling and useful auditory sensations. One patient, with 21 activated electrodes, has achieved functional open-set speech understanding. The second patient, with 7 activated electrodes, has benefited from environmental sound awareness and improved lipreading. The last, blind, patient, with 4 electrodes activated, achieved only perception of environmental sounds.
Degenerative arthrosis of the shoulder is less commonly diagnosed than at the joints of the lower extremity. The shoulder joint does not bear weight and some of the mechanical stresses are taken up by the subacromial space. However, anatomical studies reveal a significant incidence of degenerative changes at the glenohumeral joint with increasing age. Arthrosis is caused by mechanical loading, rotator cuff defects, and abnormal joint motion following surgery. Clinical symptoms are rarely focused on the glenohumeral joint. Clinical findings are also unspecific. Rotation of the elevated arm with compression of the joint is a reliable sign of arthrosis. The diagnosis is made with anteroposterior and axial radiographs. Ultrasonography should always be performed and computed tomography only in specific cases. Nonoperative treatment includes analgesic and antiphlogistic medication, motion therapy, and muscle exercises. Shoulder arthroplasty is favoured in advanced arthrosis. New prostheses are intended to reconstruct the normal anatomy as closely as possible.