Comparison of tensile strength of resorbable plating systems used in monocortical mandible angle osteotomy repair.

OBJECTIVE: To determine the usefulness of resorbable plating systems in load-bearing applications of the mandible and the location of critical failure. METHODS: An osteotomy was created in 24 fresh cadaveric mandibles at the angle and fixated by the Champy technique with similar resorbable craniofacial plating systems from 4 manufacturers. Each mandible was held rigid as a material test system applied a downward force anteriorly. The critical tolerance was measured and the type of failure was noted. RESULTS: Critical failure occurred at forces from 34.6 to 137.8 N. We found a statistically significant difference between the plating groups (P<.001 for all comparisons). The point of failure was almost uniformly at the plate. CONCLUSIONS: Critical failure was overwhelmingly due to rupture of the plate rather than to stripping or shearing of the screws as had been strongly expected. We found differences in plate strengths for this particular application and did not evaluate their respective long-term resorptive properties. We do not advocate that single resorbable plate fixation be the sole means of mandible angle fracture fixation, regardless of the plating system used.

A comparison of resistance to fracture among four commercially available forms of hydroxyapatite cement.

Hydroxyapatite cement is a relatively new biomaterial that has found widespread use in craniomaxillofacial surgery. Despite its common usage, complication rates as high as 32% have been reported. When failed implants are removed, implant fracture has been cited as a potential cause of failure. The purpose of this study was to evaluate resistance to fracture among 4 commercially available hydroxyapatite cement formulations. The materials tested included Norian Craniofacial Repair System (carbonated apatite cement) (AO North America, Devon, PA), Norian CRS Fast Set Putty (carbonated apatite cement) (AO North America), BoneSource (hydroxyapatite cement) (Stryker Leibinger, Portage, MI), and Mimix (hydroxyapatite cement) (Walter Lorenz Surgical, Inc, Jacksonville, FL). To ensure consistency, all materials were embedded in acrylic wells. Each material was placed into a well 2.54 cm in diameter and 0.953 cm in thickness. The materials were prepared per manufacturer specifications. All materials were incubated at 37.0 degrees C, in 6% CO2, 100% humidity for 36 hours. Using the Bionix MTS Test System, a 12-mm-diameter probe applied incremental force to the center of the disk at a rate of 0.1 mm per second. The transmitted force was measured using a Bionix MTS Axial-Torsional Load Transducer for each disk. The force which resulted in fracture was recorded for each material. Ten disks of each material were processed by this method, for a total of 40 disks. The significance of resistance to fracture for the 4 compounds was analyzed using 1-way analysis of variance with post hoc Scheffe method. Mean fracture force with related P values was plotted for direct comparison of group outcomes. Material type contributed significantly to variance in fracture force for the biomaterials studied. Norian CRS required the greatest mean fracture force (1385 N, SD+/-292 N), followed by Norian CRS Fast Set Putty (1143 N, SD+/-193 N). Mimix required a mean fracture force of 740 N, SD+/-79 N. BoneSource required a mean fracture force of 558 N, SD+/-150 N. Mimix and BoneSource required significantly less force for fracture when compared with Norian CRS and Fast Set Putty (P<0.01). Comparisons of fracture load resistance between 4 commonly used bone substitute materials have not been previously reported. Increasing biomaterial strength may reduce complications resulting from reinjury to cranioplasty sites. In this model, Norian CRS and Norian CRS Fast Set Putty demonstrated a significantly greater resistance to fracture when compared with BoneSource and Mimix.

A comparison of combinations of titanium and resorbable plating systems for repair of isolated zygomatic fractures in the adult: a quantitative biomechanical study.

Multiple studies have sought to determine the postreduction stability of internal fixation in zygomaticomaxillary complex (ZMC) fractures. Three-point fixation with titanium miniplates is increasingly recommended to repair these injuries. Use of bioresorbable plates has been suggested to eliminate potential postoperative hardware complications. By quantitatively comparing different combinations of titanium and resorbable plating systems, this study attempts to demonstrate which combinations will provide stable fixation of the fractured ZMC. Osteotomies were performed on 40 zygomas in 20 fresh-frozen cadaver skulls, simulating noncomminuted ZMC fractures. The control group (group 0) consisted of titanium plates at the zygomaticofrontal (ZF) suture, infraorbital rim (IOR), and zygomaticomaxillary buttress (ZMB). Group 1 consisted of titanium plates at the ZF and IOR, and a resorbable plate at the ZMB. Group 2 used a titanium plate at the ZF, and resorbable plates at the IOR and ZMB. Group 3 consisted of resorbable plates at the ZF, IOR, and ZMB. A mechanical test system was used to apply loads in the vectorial direction of the masseter. Critical forces and patterns of hardware failure were recorded. Group 0 failed at a mean force of 589 +/- 146 N (60 kg). Group 1 failed at a mean force of 507 +/- 124 N (52 kg). No statistically significant differences between groups 0 and 1 were found. The mean force required for failure in groups 2 and 3 was lower. Differences in the force required for failure between groups 2 and 3 and the control group was significant (P <0.05). Failure patterns were analyzed. The ZF plate tended to stretch predominantly in groups 1, 2, and 3, whereas it tended to break in group 0 (P = 0.005). The IOR plate demonstrated predictable screw failure in groups 2 and 3 (P = 0.007). For group 0, the ZF was the site of the majority of critical failures. For groups 2 and 3, the IOR was almost invariably the site of critical failure (P = 0.004). At the ZMB, there was no significant association between failure modes and it was rarely the site of critical failure, regardless of the method of fixation. However, the strength of fixation was proportional to the number of titanium plates used. Overall, the method of fixation significantly affected the force required for mechanical failure of ZMC fractures (P <0.0001). The presence of teeth significantly increases the force required for implant failure in ZMC fracture fixation when combinations of plates are used (P = 0.038). All combinations of titanium and resorbable plates may be sufficient to overcome the displacing forces produced by the masseter and may be used for internal fixation of isolated ZMC fractures in the adult.

Comparison of bacterial inoculation and transcutaneous oxygen tension in the rabbit S1 perforator and latissimus dorsi musculocutaneous flaps.

Muscle and musculocutaneous flaps have been used reliably in reconstruction of soft-tissue defects for many years. Previous experimental studies have shown musculocutaneous flaps to be superior to the random pattern and fasciocutaneous flaps in the management of infected wounds. Over the past decade, perforator flaps have gained acceptance as alternative methods of reconstruction in the clinical setting that can decrease donor-site morbidity and hospital stay, and increase patient satisfaction. The authors theorized that perforator flaps may be able to handle infected wounds better than random pattern and fasciocutaneous flaps because their blood supply is essentially the same as many of their musculocutaneous counterparts. The goal of this study was to compare the S1 perforator-based skin flap and latissimus dorsi musculocutaneous flap in the dorsal flank of the rabbit with the introduction of bacteria to simulate both superficial and deep wound infection. Measurements of oxygen tension and regional perfusion index were performed on both types of flaps to ascertain their viability and capacity to heal. The authors found no statistical significance between latissimus dorsi musculocutaneous and S1 perforator flaps in the rabbit with respect to superficial and deep wound infections. The regional perfusion index was calculated for postoperative days 1, 2, and 4. No statistically significant difference between the two flaps using the regional perfusion index could be identified. Additionally, regional perfusion for both types of flaps was greater than 0.6, indicating that their capacity to heal wounds is similar.

Advantages of perforator flaps in reconstruction of complex defects of the head and neck.

Microsurgical transfer of vascularized tissue during the past three decades has allowed highly complicated postoncologic defects in the head and neck region to be reconstructed. Recently, perforator flaps have been used to reduce postoperative pain, shorten hospital stay, and lessen donor-site complications. These flaps are offsprings of previously known musculocutaneous and fasciocutaneous flaps and are harvested with preservation of the underlying muscular and fascial structures. The vascularized skin and soft-tissue envelope is supplied by perforating branches from the parent vessel. Less is known about the performance of these flaps in the head and neck region. During a 4-year period, 22 patients at our institution underwent reconstruction of the head and neck region with deep inferior epigastric perforator (DIEP) or thoracodorsal artery perforator (TDAP) flaps. All but one of the flaps survived. Advantages noted include: (1) longer vascular pedicles, (2) less postoperative pain, (3) less donor-site deformity, (4) improved aesthetic outcome, (5)potential for a neurosensory flap, (6) potential for an osteocutaneous flap, and (7) ease of postoperative radiologic follow-up. The DIEP flap can be harvested concurrent with oncologic resection, with the patient in the supine position. The TDAP flap is dissected with the patient in the decubitus position, creating an additional step to change operative position, and separates extirpative and reconstructive stages.

Diagnosing and treating nasal septal perforations.

The authors present a comprehensive treatment guide to nasal septal perforations. Successful surgical repair requires vascularized tissue flaps, interpositional tissue scaffolding, and tension-free closure. However, surgical techniques vary with the size of the defect, and there is no single universally effective procedure.

The thoracodorsal artery perforator-scapular osteocutaneous (TDAP-SOC) flap for reconstruction of palatal and maxillary defects.

Despite technical advances over the past 3 decades, subtotal, total, and extended total maxillectomy defects remain challenging reconstructive problems. In particular, postoncologic resection of the maxilla results in complex 3-dimensional defects of the midface, which cause severe functional and esthetic deformities. Such defects generally require composite tissue flaps for reconstruction. Rebuilding the palate and maxilla is especially challenging because it requires reconstitution of the facial buttresses, occlusion, replacement of bony hard palate, and the thin intraoral and intranasal lining which normally constitute the soft palate. Various methods of reconstruction have been applied to this area in search of an ideal soft tissue-bone flap to restore the bony framework of the maxilla and palate while providing an internal lining. Osteocutaneous and osteomuscular flaps such originating from the scapular, iliac, peroneal, and radial vascular systems have been attempted with good success. We devised an osteocutaneous flap based on the scapular vascular system, which provided bone and soft tissue to successfully reconstruct the palate and maxilla in 2 patients. The skin paddle received its blood supply from the major perforating vessels of the thoracodorsal artery, and the scapular bone was nourished by the angular vessels. Although free tissue transfer using thoracodorsal perforator flaps has been described, this flap has not been previously reported in the literature as an osteocutaneous tissue transfer. With the use of rigid fixation, excellent results have been obtained with this technique for palatal and maxillary reconstruction.

Simultaneous bilateral breast reconstruction with superior gluteal artery perforator (SGAP) flaps.

The superior gluteal artery perforator (SGAP) flap is a useful technique for restoration of the breast after mastectomy. If appropriately planned, the soft-tissue envelope supplied by the superior gluteal artery perforator vessels can be harvested with minimal donor site morbidity and often results in a highly esthetic restoration of the breasts. Dissection of the flap is performed with complete preservation of gluteus maximus muscle function. The resulting vascular pedicle obtained via dissection through the muscle is longer than that of gluteal musculocutaneous flaps and affords the surgeon the luxury of avoiding vein grafts in the anastomotic phase of surgery. Despite these advantages, use of the SGAP flap is not popular among reconstructive surgeons. Many practitioners are not familiar with the vascular anatomy of the gluteal area and may not be comfortable with the dissection of the parent vessels or lack the desire to practice microsurgery. On the other hand, our group has reported the largest experience to date with this method of breast reconstruction and has found the SGAP flap to be a reliable and safe method of autologous breast restoration in unilateral absence of the breast. Although the indications to perform single-stage gluteal tissue transplantation for bilateral breast restoration are uncommon, they do occasionally arise in clinical practice. We have carried out concurrent bilateral breast reconstruction using SGAP flaps on 6 patients with acceptable overall morbidity. All flaps went on to survive and resulted in highly esthetic restorations of the breast. Though a challenging undertaking, in-unison transfer of bilateral SGAP flaps serves as a useful option for a subset of patients desiring 1-stage bilateral breast reconstruction.

Variability of the postauricular muscle complex: analysis of 40 hemicadaver dissections.

BACKGROUND: The postauricular area is often explored by reconstructive and otologic surgeons. We previously reported on the use of postauricular tissues as a graft for wrapping hydroxyapatite implants in orbital reconstruction. This procedure reduced the incidence of implant exposure, while achieving acceptable cosmetic results. Although much is known about the postauricular area, muscle and fascial relationships and potential variations in anatomy remain ill defined. OBJECTIVES: To identify and analyze variations in the patterns of the postauricular muscle complex (PMC) and to study the relationships of the fascial contributions from the components that make up the PMC. METHODS: Dissections were performed using 40 fresh specimens. Muscular and fascial components of the PMC were dissected, analyzed, and photographed. RESULTS: The PMC receives contributions from the occipitalis and trapezius muscles, the deep temporal and sternocleidomastoid fasciae, and the superior and posterior auricular and platysma muscles. Major contributors to the PMC were present in every specimen. Minor contributors were more variable in their presence and contributions. The posterior auricular muscle was identified as having several muscle bundles in 1 specimen and absent in 2 specimens (5%). The occipitalis fascia was seen to insert superior to the auricle and to blend with the deep temporal fascia in 3 cases (7%). The platysma muscle contributed to the PMC in 8 cases (20%). CONCLUSIONS: This study demonstrated important variations in the presence and contributions of 7 previously known muscular structures and their role in forming the PMC. Seven distinct patterns are identified, and the potential clinical implications of these anatomical variations are illustrated.

Use of the deep inferior epigastric perforator flap in a 15-month-old boy after resection of lymphatic malformation.

Lymphatic malformations are benign tumors that arise from congenital defects of the lymphatic system. Despite the fact that all lymphatic malformations develop embryologically, their presence may not be detected until the tumor enlarges from hemorrhage or infection. Typical of these tumors is a slow-growing, asymptomatic phase with the potential for rapid and massive expansion and a tendency to infiltrate into surrounding tissues. These tumors are associated with a high rate of recurrence, especially with incomplete excisions. To minimize the chance of recurrence, a complete resection of a groin microcystic lymphatic malformation was performed on this 15-month-old boy, creating a significant defect in the upper thigh. Immediate coverage was felt to be the best option for reducing any associated morbidity. We used a skin-soft tissue flap supplied by perforators of the deep inferior epigastric artery to repair the wound. Using this technique, the musculofascial structures in the abdominal wall were completely spared, and the skin and fat were transferred on a vascular leash to the desired location. The donor site was closed by approximating the fascial edges without tension. The defect on the thigh was filled with tissue of similar thickness and characteristics, avoiding potential contour irregularities and color mismatch. The deep inferior epigastric perforator (DIEP) flap is a useful option for groin defects and can be applied safely in the pediatric population.

The thoracodorsal artery perforator flap: clinical experience and anatomic study with emphasis on harvest techniques.

The thoracodorsal artery perforator flap is a relatively new flap that has yet to find its niche in reconstructive surgery. At the authors' institution it has been used for limb salvage, head and neck reconstruction, and trunk reconstruction in cases related to trauma, burns, and malignancy. The authors have found the flap to be advantageous for cranial base reconstruction and for resurfacing the face and oral cavity. The flap has been used successfully for reconstruction of traumatic upper and lower extremity defects, and it can be used as a pedicled flap or as a free tissue transfer. The perforating branches of the thoracodorsal artery offer a robust blood supply to a skin-soft-tissue paddle of 10 to 12 cm x 25 cm, overlying the latissimus dorsi muscle. The average pedicle length is 20 cm (range, 16 to 23 cm), which allows for a safe anastomosis outside the zone of injury in traumatized extremities; the flap can be made sensate by neurorrhaphy with sensory branches of the intercostal nerves. Vascularized bone can be transferred with this flap by taking advantage of the inherent vascular anatomy of the subscapular artery. A total of 30 pedicled and free flap transfers were performed at the authors' institution with an overall complication rate of 23 percent and an overall flap survival rate of 97 percent. Major complications, such as vascular thrombosis, return to the operating room, fistula formation, recurrence of tumor, and flap loss, occurred in 17 percent of the patients. Despite these drawbacks, the authors have found the thoracodorsal artery perforator flap to be a safe and extremely versatile flap that offers significant advantages in acute and delayed reconstruction cases.

Bilateral breast reconstruction with the deep inferior epigastric perforator (DIEP) flap: an experience with 280 flaps.

Bilateral prophylactic mastectomy can reduce the incidence of breast cancer by 87 to 93% in high-risk individuals and is an appealing option for many patients if reconstruction can be provided with acceptable morbidity and outstanding esthetic results. Autogenous breast reconstruction techniques have evolved over the last 20 years to meet this goal. Familiarity with the deep inferior epigastric perforator (DIEP) flap led us to carry out simultaneous bilateral breast reconstruction with acceptable morbidity and superior esthetic outcome in 3 patient groups: (1) after bilateral prophylactic mastectomy, (2) after therapeutic and contralateral prophylactic mastectomy, and (3) after explantation of bilateral implant failures. A retrospective review of our experience with 280 flaps in 140 patients was performed. Average operating times, including time for implant removal or mastectomy and reconstruction, was 7.3 hours. Average hospitalization was 3.9 days. Significant perioperative complications occurred in 9 patients (6.4%); all returned to the operating room. This included 7 microvascular complications, 1 hematoma, 1 seroma, and 1 DVT. Less significant complications were divided into early and late. The early complications included 1.8% partial flap necrosis, 4.2% abdominal apron necrosis greater than 5 cm2, 2.9% seromas that required intervention, and 5.7% partial breast flap dehiscence. Late complications included 12.5% fat necrosis of any size and 2.1% hernia formation. Smoking, obesity, age, history of chest wall radiation, and flap size were evaluated as risk factors for increased morbidity.

Breast reconstruction with gluteal artery perforator (GAP) flaps: a critical analysis of 142 cases.

Fujino was the first to introduce gluteal tissue as a free flap for breast reconstruction. The use of the musculocutaneous flap from the buttock in breast reconstruction has been championed by Shaw. Despite the initial enthusiasm for this area as a donor site, few other large series exist on the subject. Two decades of experience with this region as a donor site led to recognition of advantages and drawbacks. Furthermore, use of both the superior and inferior gluteal musculocutaneous flap was associated with certain important donor site complications and the use of vein grafts to allow for microvascular anastomosis. The evolution of free tissue transfer has progressed to the level of the perforator flap. This reconstructive technique allows elevation of tissue from any region consisting only of fat and skin. This minimizes donor site morbidity by allowing preservation of the underlying muscle and coverage of important structures in the region such as nerves. The superior and inferior gluteal perforator flaps have been used at our institution for breast reconstruction since 1993. The superior gluteal artery perforator (S-GAP) flap is our preferred method of breast reconstruction when the abdomen is not available or preferable. We report the result of this flap over the past 9 years and point out important surgical refinements, advantages, disadvantages, and lessons learned during this time.

The bare area of the upper conjunctiva: a closer look at the anatomy of transconjunctival upper blepharoplasty.

Transconjunctival upper blepharoplasty is a novel technique for which the overall experience has been limited. The authors have used this technique in 42 patients for eyelid rejuvenation, with predictable results and low morbidity. The authors previously described the "bare" area in the medial upper conjunctiva, which was initially noted during their clinical series. This area serves as an anatomic window to access the medial upper eyelid fat pad with a high degree of safety. To clarify the anatomy of this approach, an anatomic study of the upper medial eyelid was performed on the orbits of 10 cadavers (20 orbits). The bare area was further elucidated during these dissections and its microscopic components described in detail. Its spatial relationship to the medial orbital wall and trochlea was also examined during this study. The authors hope that these findings will aid surgeons planning to use this technique.

New technique for nipple areola reconstruction: arrow flap and rib cartilage graft for long-lasting nipple projection.

The nipple-areola complex is an integral part of breast reconstruction. It serves as an important landmark for the new breast and many techniques have been described for its reconstruction. Historically, nipple projection has been most difficult to achieve and maintain. The authors found that techniques that use isolated soft tissue flaps eventually fail secondary to scar contraction with loss of projection. Since 1994, the authors have used a local skin fat flap shaped as an arrow for the reconstruction of the nipple on 454 breasts. The arrow shape is advantageous because it allows the scar to be broken on closure, minimizing postoperative wound contracture. Within the flap, the authors routinely use a rib cartilage graft, which provides additional support and projection for the skin-soft-tissue envelope. The graft is harvested during the initial breast flap transfer for the purpose of exposing the internal mammary vessels and has been obtained without any additional morbidity. By combining a skin fat flap and rib cartilage graft, the authors have achieved excellent long-term projection and a more esthetically pleasing nipple reconstruction.