David Genecov - Academia.edu (original) (raw)

Papers by David Genecov

Distraction osteogenesis (DO) is an effective way to treat severe maxillary deficiency in patient... more Distraction osteogenesis (DO) is an effective way to treat severe maxillary deficiency in patients with cleft lip and palate. It has been reported to have long-term stability and low relapse rate compared with conventional maxillary osteotomy in large maxillary movement. However, complications such as nonunion are seldom reported. While developing our external distraction techniques, we had 4 nonunion cleft lip and palate (CLP) patients. The aim of this study is to analyze the possible reasons for these conditions by comparing them to patients successfully treated at 1 craniofacial institute. Fifty-six patients with CLP deformities treated with external maxillary distraction from 2000 to 2006 in 1 craniofacial center were reviewed. Among them, 17 had full records and follow-up time of more than 1 year. They had rigid external halo distraction with dental splint after a high Le Fort I osteotomy. Distraction was started at 5 days with a rate of 1 mm per day until the maxilla acquired the planned correction. Consolidation time ranged from 4 weeks to 3 months. Patients&amp;amp;amp;amp;amp;amp;amp;#39; general information, DO protocol, and cephalometric radiograph measurements before DO, immediately after DO, and follow-ups were evaluated. Thirteen of 17 patients successfully completed DO, whereas 4 others developed dental occlusion relapse 2 to 3 months after device removal. Later jaw surgery showed nonunion at the distraction sites. These were our first patients treated with external distraction. Their consolidation time was from 4 to 6 weeks with a mean of 5.2 weeks. After increasing the consolidation time up to 12 weeks, all of the other 13 patients had successful results without nonunion. Their mean consolidation time was 9.8 weeks. The nonunion group had significantly shorter consolidation time, older age, and larger distraction osteogenesis (DO) advancement than the successful group statistically. There was also a greater percentage of bilateral CLP patients in the nonunion group than in the successful treatment group. Among the 4 nonunion patients, 2 had failed alveolar bone graft before DO, and 3 did not have face mask retention therapy after device removal. The horizontal relapse rate in the 13 successful patients was 1 to 3 mm (mean, 11.9%) after 1 to 3 years of follow-up. All of these patients had good occlusion in the short-term follow-up (1 yr). Five developed end-to-end or Class III malocclusion in the long-term follow-up (1-3 yrs) because of maxillary relapse and continued mandibular growth that required jaw surgery later. A short consolidation time can cause nonunion, and should be lengthened to 12 weeks or more for a stable maxilla. Older age, bilateral CLP, large DO advancement (&amp;amp;amp;amp;amp;amp;amp;gt;15 mm), and compromised bone healing are the risk factors for nonunion.

Plastic and Reconstructive Surgery, 1999

Degloving injuries of the hand and foot pose difficult reconstructive and rehabilitation challeng... more Degloving injuries of the hand and foot pose difficult reconstructive and rehabilitation challenges. After an excellent experience with split-thickness skin grafting with the vacuum-assisted closure device, we began studies with full-thickness skin grafts and traumatized skin. The device has been used with successful reapplication of full-thickness degloved skin in two patients. The first patient suffered degloving of the foot; the second patient, degloving of the hand.

Plastic and Reconstructive Surgery, Dec 1, 2007

Three Dimensional Facial Sculpting, 2006

Ventricular assist devices augment flow from the left atrium to the aorta and/or from the right a... more Ventricular assist devices augment flow from the left atrium to the aorta and/or from the right atrium to the pulmonary artery. Most devices are used in the asynchronous full-to-empty mode (asynchronous) but may also be used in a synchronous counterpulsation mode (synchronous). This study determines the optimal assist modes to reduce myocardial oxygen consumption (MVO2) and metabolism. Twelve pigs were instrumented with carotid artery and Baim coronary sinus catheters for determination of MVO2 and myocardial lactate production (LACT). Six were implanted with a Pierce-Donachy left ventricular assist device (LVAD) and 6 with both right and left ventricular assist devices (BIVAD). Two periods each of control, synchronous, and asynchronous bypass were instituted, the midanterior descending coronary artery (LAD) was ligated, and the sequence was repeated. After each period, MVO2 and LACT were determined and myocardial biopsy specimens were obtained for tissue, lactate, and ATP assay. Following LAD ligation, biopsy specimens were obtained from both the infarct and noninfarct zones of the heart. MVO2 decreased (p &amp;lt; 0.05) in the asynchronous BIVAD mode compared with control. MVO2 was unchanged in synchronous BIVAD or either LVAD mode. Tissue ATP and tissue lactate were unaffected by any mode of bypass. Only BIVAD in the asynchronous mode reduced MVO2. When ventricular assist devices are utilized to aid recovery of the natural heart, two devices should always be inserted to allow biventricular assist. Synchronous counterpulsation offers no advantage.

Plastic and Reconstructive Surgery, 2007

Southern Medical Journal, 1997

Spontaneous rupture of abdominal aortic aneurysm into the inferior vena cava is rare. The clinica... more Spontaneous rupture of abdominal aortic aneurysm into the inferior vena cava is rare. The clinical presentation is highly variable, and the diagnosis can be difficult, often being made only at operation. The aortocaval fistula results in a large left-to-right shunt, which can cause cardiac failure. Once the diagnosis is made, treatment is by surgical closure of the fistula and repair of the aneurysm with a graft. This is a retrospective review of a single surgeon's experience with aortocaval fistula complicating abdominal aortic aneurysms. Over a 15-year period, we had five patients with spontaneous aortocaval fistula who were treated operatively. Preoperative diagnosis was made in two, suspected in one, and not made in two, one of whom died (the only perioperative death in the series). Spontaneous aortocaval fistulas are uncommon, and their preoperative recognition is difficult. Hematuria in association with an abdominal aortic aneurysm should raise the suspicion of an aortocaval fistula. Surgical correction is possible, with survival rates comparable to those associated with rupture of aneurysms into the retroperitoneum. Early operative control of the fistula is important to optimize the preload to the heart.

Plastic and Reconstructive Surgery, 2005

The aim of this study was to investigate the prevalence of abnormal preoperative screening prothr... more The aim of this study was to investigate the prevalence of abnormal preoperative screening prothrombin time and partial thromboplastin time in patients listed for primary cranial vault remodeling that required hematologic workup and their diagnoses and subsequent management. This retrospective analysis was performed from January of 2000 to December of 2003 at the International Craniofacial Institute, Dallas, Texas, on a total of 168 patients. All patients had a normal prothrombin time. Abnormally raised partial thromboplastin time was found in six patients (prevalence of 3.57 percent), one who had factor XI deficiency, one who had a borderline factor XI deficiency and circulating inhibitor, one who had an intermittent factor XI deficiency and circulating inhibitor, one who had a borderline von Willebrand&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s disease with low factor XII, and the remaining two who had a circulating inhibitor of coagulation. Of these six patients, the perioperative management was altered in four of five patients, and one patient declined surgery out of fear of surgical morbidity. The surgery of one patient was aborted intraoperatively because of abnormal bleeding without clot formation after the calvarial burr holes had been drilled. The mean blood loss was 183 ml for the four patients with completed surgery and 100 ml for one patient. The authors conclude that even though the prevalence of abnormal screening partial thromboplastin time in these patients was low (3.57 percent), detection of an abnormal result required preoperative correction of coagulopathy in 80 percent of cases.

Plastic & Reconstructive Surgery, 1999

Journal of Oral and Maxillofacial Surgery, 2008

Purpose: Cranial defect reconstruction presents 2 challenges: induction of new bone formation, an... more Purpose: Cranial defect reconstruction presents 2 challenges: induction of new bone formation, and providing structural support during the healing process. This study compares quantity and quality of new bone formation based on various materials and support frameworks. Materials and Methods: Eighteen dogs underwent surgical removal of a significant portion of their cranial vault. Demineralized bone matrix was used to fill the defect in all animals. In 9 dogs, recombinant human bone morphogenetic protein-2 (rhBMP-2) was added, while the other 9 served as the non-rhBMP-2 group. In each group, 3 animals were fixed with cobalt chrome plates, 3 with adding platelet-rich plasma, and 3 fixed with a Lactosorb (Walter Lorenz Surgical, Inc, Jacksonville, FL) resorbable mesh. Necropsy was done at 12 weeks postoperative. Histomorphometry, density, and mechanical properties of the regenerate were analyzed. Results: The non-rhBMP-2 groups showed minimal substitution of demineralized bone matrix with new bone, while only sporadic remnants of demineralized bone matrix were present in the rhBMP-2 groups. The defect showed more new bone formation (P Ͻ .001) and density (P Ͻ .001) in the rhBMP-2 groups by Kruskal-Wallis test. The area of new bone was not significantly different among the rhBMP-2 subgroups. The resorbable mesh struts showed no sign of bone invasion or substitution. In the non-rhBMP-2 resorbable mesh group, demineralized bone matrix almost totally disintegrated without replacement by new bone. Conclusions: The addition of rhBMP-2 to demineralized bone matrix accelerated new bone formation in large cranial defects, regardless of the supporting framework or the addition of platelet-rich plasma. The use of a resorbable mesh in such defects is advisable only if rhBMP-2 is added.

Journal of Craniofacial Surgery, 2008

Objective: This study was designed to investigate the optimal combination of known osteogenic bio... more Objective: This study was designed to investigate the optimal combination of known osteogenic biomaterials with shape conforming struts to achieve calvarial vault reconstruction, using a canine model. Methods: Eighteen adolescent beagles were divided equally into 6 groups. A critical size defect of 6 x 2 cm traversed the sagittal suture. The biomaterials used for calvarial reconstruction were demineralised perforated bone matrix (DBM), recombinant human bone morphogenetic protein-2 (rhBMP2) and autogenous platelet-rich plasma (PRP). The struts used were cobalt chrome (metal) or resorbable plate. The groupings were as follows: 1) DBM + metal, 2) DBM + PRP + metal, 3) DBM + PRP + resorbable plate, 4) DBM + rhBMP2 + metal, 5) DBM + rhBMP2 + PRP + metal, and 6) DBM + rhBMP2 + resorbable plate. Animals were euthanised at 3 months post-surgery. There was no mortality or major complications. Analysis was performed macroscopically, histologically, and with computed tomography (CT). Results: There was complete bony regeneration in the rhBMP2 groups only. Non-rhBMP2 groups had minimal bony ingrowth from the defect edges and on the dural surface, a finding confirmed by CT scan and histology. PRP did not enhance bone regeneration. Shape conformation was good with both metal and resorbable plate. Conclusion: rhBMP2 but not PRP accelerated calvarial regeneration in 3 months. The DBM in the rhBMP2 groups were substituted by new trabecular bone. Shape molding was good with both metal and resorbable plate.

Journal of Craniofacial Surgery, 2003

A 33-year experience with a proven method of repair for primary unilateral cleft lip-nose is pres... more A 33-year experience with a proven method of repair for primary unilateral cleft lip-nose is presented. The technique used by the authors has been improved by modifications that have led to better symmetry and balance with less scarring. The technique involves ignoring the abnormal skeletal base, use of perisurgical passive orthopedics, and primary surgical correction of the nose and lip. Improved results can consistently be achieved by approaching the nose laterally through an inferior turbinate incision, freeing completely the lip and nose components so they can be translocated to match the normal side. Accurate positioning and symmetry of the alar base and sill is aided by limiting the transverse incision in the lip. This results in less scarring and improved sill reconstruction. The technique for floor-of-the-nose reconstruction avoids a small nostril without discarding any tissue. It is important to leave tissue in the floor to compensate for the skeletal deficiency. The senior author has performed this procedure in more than 750 patients. Approximately 35% have or will require minor secondary reconstruction at age 5 years. An aesthetic rhinoplasty is performed on most patients after growth is complete. Self-esteem is enhanced by early nasal reconstruction and has become the authors&amp;amp;#39; standard of care for rehabilitation of the unilateral cleft lip and palate. Many surgeons remain reluctant to perform primary nasal repair. With careful proper technique, any experienced cleft surgeon can learn this procedure. For the beginner, conservatism is recommended.

Journal of Craniofacial Surgery, 2009

The objective of this study was to evaluate the long-term success of mandibular distraction osteo... more The objective of this study was to evaluate the long-term success of mandibular distraction osteogenesis in patients with mandibular airway obstruction syndrome (MAOS), defined as obstructive sleep apnea, swallowing abnormalities, and failure to thrive in the presence of micrognathia, glossoptosis, gastroesophageal or laryngeal reflux, and microaspiration. This is a cross-sectional study at the International Craniofacial Institute in the Medical City Hospital, Dallas, TX. From January 1997 to July 2008, a group of 81 patients were examined for MAOS using medical history and physical examination. They all met the criteria for a multidisciplinary team evaluation consisting of upper airway endoscopy, swallowing evaluations, standard overnight polysomnography, and radiologic evaluations of the airway and craniofacial structures. In the 81 patients examined, Pierre Robin Sequence was diagnosed in 65; micrognathia and glossoptosis without cleft palate, in 13; and micrognathia as a component of a craniofacial syndrome (Treacher Collins syndrome), in 3. A total of 45 patients were documented to have gastroesophageal or laryngeal reflux.Only 41 patients had yet to receive any treatment at the time of evaluation; 40 patients presented with a tracheotomy.Of the 41 untreated patients, 14 responded to conservative treatment; Pierre Robin syndrome was diagnosed in all of them, and they did not require mandibular distraction or other surgical procedure to improve the MAOS.Bilateral distraction osteogenesis of the mandible was performed in 67 patients; 27 were younger than 6 months at the beginning of the distraction, and 40 were older than 6 months (mean age at distraction, 1.2 yr). Of this group, 26 patients did not have any prior surgical treatment, and 41 patients already had a tracheotomy. The distraction devices used were internal in 33 (49.26%) and external in 34 (50.74%) of 67 patients. The distraction protocol consisted of a 24-hour latency period and then a 1-mm/d activation period. The mean activation period was 19.4 days (range, 10-27 d), the mean consolidation period was 73 days, and the mean length of distraction was 22 mm (range, 10-32 mm). Tracheostomy was prevented in 25 (96%) of 26 patients, and decannulation after distraction was possible in 38 (92%) of 41 patients. Success, defined as decannulation within 1 year of the start of distraction or prevention of tracheostomy in a patient otherwise deemed as a candidate, was found in 63 (94%) of 67 patients. Oral feedings have been resumed in 61 (91%) of 67 patients.Complications observed were mostly related to pin site infections requiring antibiotics. Device failure was experienced in 2 (3%) of 66 internal devices and in 7 (10.2%) of 68 external devices.Distraction osteogenesis of the mandible provides an excellent treatment for mandibular airway obstruction in patients younger than 6 years who do not respond to conservative measures and allows for early decannulation in patients who previously underwent tracheotomy.

International Congress Series, 2005

The Cleft Palate-Craniofacial Journal, 2013

Purpose : The effects of recombinant human bone morphogenetic protein-2 (rhBMP-2) and osteogenic... more Purpose : The effects of recombinant human bone morphogenetic protein-2 (rhBMP-2) and osteogenically differentiated adipose tissue-derived stem cells (ADSC) on new bone formation in high-speed distraction osteogenesis of adult rabbit cranium were investigated. Materials and Methods : A total of 41 adult rabbits were used in the study. Distraction began after a 5-day latency period at a rate of 1.5 mm twice a day until 10-mm length gain was obtained both in the control group, where a bone defect was induced, and in the experimental group, in which ADSC (group A), rhBMP-2 (group B), or both (group C) were injected in the distraction gap after distraction. At 4, 8, and 12 weeks after distraction, computed tomography analysis was done to determine the bone defect dimension and bone mineral density (BMD), while histologic examination was also done to calculate bone formation ratio. Results : Bone defect dimension significantly decreased in groups B and C, compared with the control group, at 4 and 12 weeks after distraction. BMD was significantly increased in groups B and C at 4 weeks. On histologic examination, bone formation ratio was significantly increased in group C only at 12 weeks. Conclusion : This study suggests that the use of rhBMP-2 in combination with or without ADSC is helpful to promote bone regeneration in high-speed distraction osteogenesis of adult rabbit cranium.

Child's Nervous System, 2004

Twin boys joined at the head in a total vertex configuration were born in Egypt in June 2001. At ... more Twin boys joined at the head in a total vertex configuration were born in Egypt in June 2001. At 12 months, they were transported to Dallas for evaluation and eventual surgical separation. In Dallas, a large multidisciplinary team of health care providers from two pediatric hospitals was assembled to care for the boys. Extensive radiographic evaluation revealed that the twins had essentially separate, well-formed brains, each with regions of schizencephaly. Each child&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s left cerebral hemisphere drained most of the venous blood to the right jugular system of the other. A detailed assessment of the foreseeable risks of surgical separation was then estimated and presented to the parents, as well as to the ethics committee of the two institutions. The decision was then made to proceed with separation. Surgical planning included the construction of multiple polymer models, and the design and construction of customized head holders and an operating table. Prior to separation a series of preparatory operations were performed to expand the scalp, as well as the fascia lata for dural grafting. At the age of 28 months, the twins were successfully separated during a 33-h operation. No attempt was made to reconstruct the dural venous sinuses. Scalp closure was adequate, requiring a split-thickness skin graft on one boy. Postoperatively each child demonstrated an incomplete right hemiparesis. One twin required cerebral spinal fluid shunting. Neither child had a CSF leak or a CSF infection. At 6 months follow-up, both boys are rapidly acquiring speech in both English and Arabic, motor function is improving, and both are progressing toward independent ambulation.

Artificial Organs, 2008

Annals of Plastic Surgery, 1998

The ability to increase the rate of skin graft donor site reepithelialization significantly in a ... more The ability to increase the rate of skin graft donor site reepithelialization significantly in a cost-effective manner has important implications for the patient undergoing major reconstructive procedures. In this study the effect of externally applied reduced pressure (the V.A.C.) on the rate of healing of donor site wounds was initially investigated using a porcine model (N = 4), then repeated on humans (N = 10). Split-thickness skin grafts were harvested from the backs of pigs using standard technique. Half of the donor sites were treated with subatmospheric pressure (125 mmHg) and half were treated with an OpSite dressing. Biopsies taken every 48 hours demonstrated that sites exposed to reduced pressure healed at a much faster rate than sites treated with a standard occlusive dressing. Similarly, donor sites in humans reepithelialized faster in 7 of 10 patients, the rate was the same in 2 of 10 patients, and OpSite was faster in 1 of 10 patients. We believe this technology has the potential to be a relatively simple and cost-efficient method for increasing the rate of donor site healing.