Biomedical subjects

Mehrdad M Mofid

Publications and source records attributed to Mehrdad M Mofid.

5 recordsLinked to original sources

PubMed2004

Surgical management of hidradenitis suppurativa of the nipple-areolar complex.

Involvement of the nipple-areolar complex is an infrequent area of distribution of hidradenitis suppurativa. The difficulty of this particular distribution has been encountered in the past and resulted in bilateral mastectomies. The authors describe successful treatment of a patient with hidradenitis suppurativa of the breasts and nipple-areolar complexes using breast-conserving measures. Normal breast contour was preserved and overall cosmetic result was good.

Adult↗

PubMed2003

Spring-mediated mandibular distraction osteogenesis.

Successful performance of distraction osteogenesis requires rigorous patient compliance with a daily activation regimen of a percutaneous screw. Previous clinical studies have found that failure of patient compliance with this regimen is the most common complication leading to technical failure of the distraction process. The authors have developed an internalized spring-mediated device for mandibular distraction osteogenesis that can potentially abrogate the risks associated with patient compliance by allowing for automated distraction across an osteotomy. Twenty adult New Zealand White rabbits underwent unilateral mandibular osteotomy. A segment of nickel-titanium shape memory alloy reinforced at both ends with a pinball was fashioned into an inferiorly based arc and secured to the mandible with stainless steel wire. On postoperative day 12, spring activation commenced by cutting a wire binding the two pinballs to one another. Animals were observed for 6 weeks before they were killed. Radiographic studies and decalcified histologic analysis were performed on extracted mandibles. Temperature- and displacement-dependent properties of the shape memory alloy were also examined. Five animals were excluded from the study due to infection, nonunion, or device failure. A mean distraction of 1.2 mm in the distracted hemimandible relative to the nonoperated hemimandible was found (P <.001, two-tailed paired t test). The maximum distraction achieved in an experimental specimen using the spring distractor was 3.7 mm. There were no other histologic or radiographic differences found between study specimens and specimens subjected to traditional distraction methods. Biomechanical testing of the shape memory alloy revealed a temperature-dependent increase in force at body temperature compared with room temperature and a reduction in force with increased displacement of the spring. This study demonstrates the feasibility of spring-mediated distraction osteogenesis across an osteotomy. As the field of distraction osteogenesis matures, the next level of sophistication in the clinical development of devices will incorporate technology that permits fully internalized and automated distraction to occur.

Alloys↗

PubMed2002

Callus stimulation in distraction osteogenesis.

Distraction osteogenesis has been described as in vivo tissue engineering. The ability to stimulate this process for the repair of bony defects or lengthening of congenitally shortened facial structures is likely to significantly impact the field of craniofacial surgery. The purpose of this study was to determine whether mechanical stimulation of the distracted rabbit mandible would accelerate the maturation of the bony callus when applied during the early consolidation period. Twenty adult New Zealand White rabbits underwent unilateral mandibular osteotomy. A uni-directional internal distractor device (Synthes, Paoli, Pa.) was positioned along a plane perpendicular to the line of osteotomy. After a 7-day latency period, distraction was commenced at a rate of 1.0 mm/day for 12 days in all animals. In a control group of 10 rabbits, a consolidation period of 8 weeks was observed before they were killed. In the experimental group of 10 rabbits, daily alternate compression and distraction of 1 mm (sequential compression and distraction) was performed for 3 weeks followed by a 5-week period of rigid fixation. Each animal received a dose of a fluorescent label at three different time points during the study: at the end of the distraction period, 3 weeks after the completion of the distraction phase, and 3 days before it was killed. All animals were killed 8 weeks after the completion of the distraction phase. Undecalcified histologic analysis and 3-point bending tests to failure were performed on the extracted mandibles. The results of the experimental and control groups were compared. Four animals in the control group and three animals in the experimental group were excluded from the study because of screw loosening resulting in distractor dislodgment or because of infection. On histologic analysis, cortical thickness at the center of the callus was found to be significantly greater in the experimental group compared with the control group when normalized to the contralateral hemimandible (83 percent versus 49 percent, respectively; p < 0.007). The ratio of cortical to cancellous bone in the distracted callus was uniformly found to be greater in the experimental specimens. The mineral apposition rate was calculated by using fluorescence microscopy and found to be significantly greater in the experimental group both during the period of sequential compression and distraction (3.2 microm/day versus 2.1 microm/day, p = 0.02) and after the period of sequential compression and distraction (1.4 microm/day versus 1.1 microm/day, p = 0.006). Mechanical testing revealed no significant differences in bending strength or stiffness between experimental or control groups (p = 0.54 and 0.47, respectively). This study has demonstrated that daily alternating compression and distraction of 1 mm amplitude during the early consolidation period has a stimulatory impact on callus formation with respect to osteoblastic activity, remodeling, and maturation of bone. Optimal timing and amplitude of sequential movement, long-term biomechanical differences, and molecular pathways have yet to be elucidated.

Animals↗

PubMed2002

Viability and sensation of the nipple-areolar complex after reduction mammaplasty.

Reduction mammaplasty with nipple-areolar transposition on a medial pedicle was designed as an alternative to amputation and free nipple graft for women with severe mammary hypertrophy. The purpose of this study was to review the viability and sensory outcome of the nipple-areolar complex (NAC) in 72 women (133 breasts) after medial pedicle and inferior pedicle reduction mammaplasty between 1996 and 2000. The medial pedicle was used for 41 women (79 breasts) with moderate to severe mammary hypertrophy. An inferior pedicle was used for 31 women (54 breasts) with mild to moderate mammary hypertrophy. Mean follow-up for all patients was 25 months. Total sensation of the NAC was obtained in 68 of 79 breasts (86%) after medial pedicle reduction mammaplasty and in 50 of 54 breasts (92%) after inferior pedicle reduction mammaplasty. Total viability of the NAC occurred in 74 of 79 breasts (94%) after medial pedicle reduction mammaplasty and in 53 of 54 breasts (98%) after inferior pedicle reduction mammaplasty. Quantitative sensory testing of the NAC using the pressure-specified sensory device demonstrated that static and moving sensory thresholds of the NAC are lowest in the inferior pedicle group followed by the control group and the medial pedicle group. It can be concluded from this study that the medial and inferior pedicle techniques are capable of supporting vascularity and innervation to the NAC. The medial pedicle technique for severe mammary hypertrophy is a good alternative to free nipple grafting. The amount of breast tissue removed does not correlate with sensory outcome for both inferior and medial pedicle techniques. The pressure-specified sensory device is an excellent means of assessing sensory outcome.

Adult↗

PubMed2002

Quantitation of breast sensibility following reduction mammaplasty: a comparison of inferior and medial pedicle techniques.

The preservation of sensitivity within the nipple-areola complex is of paramount importance to patients presenting for reconstructive and aesthetic breast procedures. Previous attempts to measure sensation in the breast before and after surgery have relied primarily on the Semmes-Weinstein monofilament test, which is an imprecise study that measures the logarithm of force necessary to bend a series of six to 20 filaments. Within the last 10 years, various authors have published normative pressure threshold data for the breast that have varied by a magnitude of greater than 10-fold. Recently, precise anatomic studies have been performed that have elucidated the innervation of the nipple-areola complex medially and laterally from cutaneous branches of the intercostal nerves. Despite this knowledge, no quantitative sensibility studies have yet been performed that compare postoperative sensation when medially versus laterally innervated pedicles have been used in reduction mammaplasty. The present study is the first to use computer-assisted neurosensory testing to generate normal breast sensation data and to compare sensory outcomes between the inferior and the medial pedicle techniques of reduction mammaplasty.A total of 34 patients were divided into four groups and underwent breast sensory testing (67 breasts total) using the Pressure-Specified Sensory Device, a computer-assisted force transducer that measures static and moving one and two-point discrimination. Sensation in the nipple and in the four quadrants of the areola was measured. Groups I and II were composed of 17 unoperated controls with breast sizes ranging from 34A to 36C (group I; 18 breasts) and 36DD to 46EE (group II; 16 breasts) who presented to a general plastic surgery clinic. Groups III and IV were composed of 17 patients who underwent either medial or inferior pedicle reduction mammaplasty between July of 1997 and March of 1999. Pressure thresholds in the most sensitive breasts were as low as 0.3 g/mm2, a marked contrast to data from previous studies using Semmes-Weinstein monofilaments documenting the lowest recordable pressure threshold as greater than 2 g/mm2. Several findings from previous studies using Semmes-Weinstein monofilament testing were confirmed in unoperated controls, including an inverse relationship between sensitivity and breast size, superior nipple sensitivity when compared with the areola, and significant interpatient variability with respect to static and moving two-point discrimination among women matched according to age and breast size. When comparing medial with inferior pedicle reduction mammaplasty patients, it was found that despite significantly greater reductions using the medial pedicle technique (mean of 1.7 kg versus 1.1 kg of breast tissue removed), there were no significant differences in postoperative sensory outcomes in the sample size of 17 patients. Furthermore, within each group of patients undergoing either the medial or inferior pedicle technique, the amount of breast tissue removed did not correlate with postoperative sensory outcomes.Computer-assisted quantitative neurosensory testing is a highly accurate technique for measuring sensibility. The use of this technology demonstrates a 10-fold difference in measurable sensory thresholds in normal patients from preexisting data using Semmes-Weinstein monofilaments. Advances in measurement methods have allowed the authors to compare postoperative sensory outcomes reliably using two popular techniques of reduction mammaplasty.

Adolescent↗