Distraction osteogenesis: a new surgical technique for use with the multiplanar mandibular distractor

If distraction osteogenesis is to reach its full potential and achieve the level of accuracy that is possible with orthognathic surgery, its outcomes need to be as predictable. To this end, the authors developed a planning process for distraction osteogenesis similar to that used in orthognathic surgery. However, the success of the planning process depends on the authors' ability to execute the plan at the time of surgery. As a result, the authors needed to develop a surgical technique that would enable them to precisely install the distractor as indicated in the presurgical plan. The surgical technique presented in this article was developed for this purpose. The authors used this technique in seven patients (four boys and three girls; age range, 4 to 10 years). Four patients presented with unilateral deformities, and three patients presented with bilateral deformities. The follow-up period in this group of patients ranged from 12 to 33 months. The purpose of the technique is to replicate the position of the distractor on the mandible as determined by the presurgical plan. To this purpose, a custom drill guide and a surgical template have been developed. Both of these are used following the principles of triangulation to establish the pin position and orientation of the distractor. In the authors' hands, the use of this surgical technique has resulted in outcomes close to those predicted by the planning process.     

Transport distraction osteogenesis: a new method to heal adult calvarial defects

Popularized by Gavril Ilizarov in the 1960s, monofocal distraction osteogenesis has become a well-established method of endogenous bone engineering. This revolutionary surgical technique has significantly augmented the available reconstructive orthopedic and craniomaxillofacial procedures. Bifocal distraction osteogenesis, or bone transportation, is a modification of monofocal distraction that involves moving a free segment of living bone to fill an intercalary bone defect. Bifocal distraction has been applied successfully to reconstruct complex mandibular and long bone defects. Because traumatic or postsurgical calvarial defects do not spontaneously heal in humans older than 18 to 24 months of age, we hypothesized that bifocal distraction osteogenesis could be applied to the skull to close critical size calvarial defects. Critical size (15 x 15 mm) calvarial defects were created in eight New Zealand White rabbits. Next, a 15-mm x 10-mm calvarial box osteotomy was created just anterior to the skull defect. This osteotomy created a free bone segment that could be transported. A custom-made transport distraction device was fixed into place and the skin incision was closed. After a 4-day latency period, the distraction device was activated (0.5 mm once daily for 30 days) in seven animals; the distraction device in one animal was not activated and served as a control. All animals underwent 30 days of consolidation and were then killed. Radiographs and computed tomographic scans were performed at the following time points: end of latency period (postoperative day 4), mid-distraction (postoperative day 19), and end of consolidation period (postoperative day 64). Gross and histologic analysis was performed to evaluate the quality of the bony regenerate. The control animal healed with a fibrous union. Complete closure of the skull defects was observed in five of seven rabbits at the end of the consolidation period. One animal was removed from the study because of an early loosening of the distraction device, and one was removed because of device failure. Of the remaining five animals that completed the distraction protocol, radiographs and computerized tomographic scans showed successful ossification in all five rabbits at the end of the consolidation period. This study suggests that transport distraction osteogenesis is a promising technique that may be applied to a variety of commonly encountered craniofacial problems such as nonhealing calvarial defects.     

Customized mandibular reconstruction plates improve mechanical performance in a mandibular reconstruction model

The purpose of this paper was to analyze the biomechanical performance of customized mandibular reconstruction plates with optimized strength. The best locations for increasing bar widths were determined with a sensitivity analysis. Standard and customized plates were mounted on mandible models and mechanically tested. Maximum stress in the plate could be reduced from 573 to 393 MPa (?31%) by increasing bar widths. The median fatigue limit was significantly greater (p < 0.001) for customized plates (650 ± 27 N) than for standard plates (475 ± 27 N). Increasing bar widths at case-specific locations was an effective strategy for increasing plate fatigue performance.     

Improved osteogenesis in rat femur segmental defects treated with human allograft and zinc adjuvants

Bone allograft is widely used to treat large bone defects or complex fractures. However, processing methods can significantly compromise allograft osteogenic activity. Adjuvants that can restore the osteogenic activity of processed allograft should improve clinical outcomes. In this study, zinc was tested as an adjuvant to increase the osteogenic activity of human allograft in a Rag2 null rat femoral defect model. Femoral defects were treated with human demineralized bone matrix (DBM) mixed with carboxy methyl cellulose containing ZnCl₂ (0, 75, 150, 300 µg) or Zn stearate (347 µg). Rat femur defects treated with DBM-ZnCl₂ (75 µg) and DBM-Zn stearate (347 µg) showed increased calcified tissue in the defect site compared to DBM alone. Radiograph scoring and µCT (microcomputed tomography) analysis showed an increased amount of bone formation at the defects treated with DBM-Zn stearate. Use of zinc as an adjuvant was also tested using human cancellous bone chips. The bone chips were soaked in ZnCl₂ solutions before being added to defect sites. Zn adsorbed onto the chips in a time- and concentration-dependent manner. Rat femur defects treated with Zn-bound bone chips had more new bone in the defects based on µCT and histomorphometric analyses. The results indicate that zinc supplementation of human bone allograft improves allograft osteogenic activity in the rat femur defect model.     

The separation of anatomic components technique for the reconstruction of massive midline abdominal wall defects: anatomy, surgical technique, applications, and limitations revisited

Reconstruction of massive abdominal wall defects has long been a vexing clinical problem. A landmark development for the autogenous tissue reconstruction of these difficult wounds was the introduction of "components of anatomic separation" technique by Ramirez et al. This method uses bilateral, innervated, bipedicle, rectus abdominis-transversus abdominis-internal oblique muscle flap complexes transposed medially to reconstruct the central abdominal wall. Enamored with this concept, this institution sought to define the limitations and complications and to quantify functional outcome with the use of this technique. During a 4-year period (July of 1991 to 1995), 22 patients underwent reconstruction of massive midline abdominal wounds. The defects varied in size from 6 to 14 cm in width and from 10 to 24 cm in height. Causes included removal of infected synthetic mesh material (n = 7), recurrent hernia (n = 4), removal of split-thickness skin graft and dense abdominal wall cicatrix (n = 4), parastomal hernia (n = 2), primary incisional hernia (n = 2), trauma/enteric sepsis (n = 2), and tumor resection (abdominal wall desmoid tumor involving the right rectus abdominis muscle) (n = 1). Twenty patients were treated with mobilization of both rectus abdominis muscles, and in two patients one muscle complex was used. The plane of "separation" was the interface between the external and internal oblique muscles. A quantitative dynamic assessment of the abdominal wall was performed in two patients by using a Cybex TEF machine, with analysis of truncal flexion strength being undertaken preoperatively and at 6 months after surgery. Patients achieved wound healing in all cases with one operation. Minor complications included superficial infection in two patients and a wound seroma in one. One patient developed a recurrent incisional hernia 8 months postoperatively. There was one postoperative death caused by multisystem organ failure. One patient required the addition of synthetic mesh to achieve abdominal closure. This case involved a thin patient whose defect exceeded 16 cm in width. There has been no clinically apparent muscle weakness in the abdomen over that present preoperatively. Analysis of preoperative and postoperative truncal force generation revealed a 40 percent increase in strength in the two patients tested on a Cybex machine. Reoperation was possible through the reconstructed abdominal wall in two patients without untoward sequela. This operation is an effective method for autogenous reconstruction of massive midline abdominal wall defects. It can be used either as a primary mode of defect closure or to treat the complications of trauma, surgery, or various diseases.     

Free-flap mandibular reconstruction: a 10-year follow-up study

Free-flap reconstruction of oncologic mandibular defects has become the modern standard of care. However, no previous studies have established the long-term results of such reconstructions. The objective of this study was to review functional and aesthetic outcomes in patients a decade after free-flap mandibular reconstruction.A single surgeon's experience with free-flap reconstruction of the mandible was retrospectively reviewed. Eighty-two consecutive patients who underwent reconstruction from January of 1987 to December of 1990 were identified. Of the 34 patients still alive, 20 agreed to participate (response rate, 59 percent). To assess complications and functional outcome, patients were interviewed using validated questions and questions developed specifically for the study. Aesthetic outcome was judged by two independent observers. Panorex radiographs were obtained to assess bone resorption. Bone height was measured at standardized locations on the body, ramus, and symphysis and compared with the immediate postoperative Panorex radiographs. Differences in Panorex magnification were adjusted for by comparison of miniplate measurements. Mean length of follow-up was 11 years. Mean patient age at the time of the study was 48 years. Nineteen of 20 patients had malignant disease, one of whom had a local recurrence during the follow-up period. Two patients received radiation therapy preoperatively and 13 postoperatively. Mean length of mandible resection was 13 cm. Defect types were as follows (Jewer's classification): 12 L, 4 H, 3 LC, and 1 LCL. All flaps survived.At 10-year follow-up, aesthetic outcome was judged to be excellent in 55 percent of patients, good in 20 percent, fair in 15 percent, and poor in 10 percent. The aesthetic results were remarkably stable over time. Slight accentuation of subtle postoperative asymmetry became evident as facial aging progressed. Dental rehabilitation in the study group included five patients with osteointegrated implants and seven with conventional dentures. Seventy percent of patients reported a regular diet. The remainder required a soft diet. Food tolerance was good, as rated by the List Scale (mean score, 77 percent). Seventeen patients had easily intelligible speech, whereas three were intelligible with effort. At the midbody of the mandible, 92 percent of the postoperative bone height was preserved; at the midramus, 93 percent was maintained; and at the symphysis, 92 percent remained. In several patients, there was greater age-related bone loss from the residual native mandible compared with the reconstructed site. One patient developed an orocutaneous fistula following postoperative radiation therapy. Nine patients had miniplates removed, either because of plate problems or to allow implant placement. There were no cases of osteoradionecrosis, bone fracture, or miniplate fracture. There was no significant long-term disability related to the donor site.Free-flap reconstruction of the mandible provides excellent functional and aesthetic results that remain stable over time. Bone resorption is surprisingly minimal, even in the face of postoperative radiation therapy. The majority of patients are able to tolerate a regular diet and to either wear dentures or acquire osteointegrated implants. Acceptable speech and appearance are restored and continue to be a source of patient satisfaction at least a decade after surgery.     

Free fibula osteoseptocutaneous-pedicled pectoralis major myocutaneous flap combination in reconstruction of extensive composite mandibular defects

Lateral composite mandibular defects resulting from excision of advanced oral carcinoma often require mandible, intra-oral lining, external face, and soft-tissue bulk reconstruction. Ignorance of importance soft-tissue deficit in those patients may cause significant morbidity and functional loss. Such defects, therefore, can be reconstructed best with a double free flap technique. However, this procedure may not be feasible for every patient or surgeon. An alternative procedure is a free fibula osteoseptocutaneous flap combined with a pedicled pectoralis major myocutaneous flap. This combination was used in reconstruction of extensive composite mandibular defects in 14 patients with T3/T4 oral squamous cell carcinoma. All patients were men, and the average age was 54.3 years. The septocutaneous paddle of the fibula flap was used for the mucosal lining of the defects while the bony part established the rigid mandibular continuity. The pectoralis major flap then covered the external skin defect in the face and cheek, and the dead spaces left by the extirpated masticator muscles, buccal fat, and parotid gland. One free fibula flap failed totally, and one pectoralis major flap developed marginal necrosis. At the time of final evaluation, nine patients (64.3 percent) were alive, surviving an average of 25.7 months. All patients eventually regained their oral continence and an acceptable cosmetic appearance. In conclusion, the fibula osteoseptocutaneous flap plus regional myocutaneous flap choice is a successful and technically less demanding alternative to the double free flap procedures in reconstruction of extensive lateral mandibular defects.     

Vascular leak syndrome of Sprague-Dawley rats in a mandibular distraction osteogenesis study

Vascular leak syndrome (VLS) is a common and often fatal sequela of multiple bone traumas, and of infectious, toxic, and allergic insults in human patients. Although an animal model for VLS has not been fully established, rats have shown sensitivity to the syndrome that approximates that of the human population. We describe cases of VLS in three-month-old adult and one-month-old Sprague-Dawley rats in an osteogenesis study aimed at optimizing correction of bone hypoplasias and other craniofacial deformities in children, using a mandibular distraction device. In the study reported here, VLS was diagnosed in 40% of the rats that were necropsied after dying or being euthanized early, subsequent to mandibular osteotomy, a procedure that involves minimal bone trauma. The gross and histologic findings, as well as the clinical course of VLS in the rats of the osteogenesis study, were similar to those of documented human cases. Hence, the rat may be a useful animal model to h elp characterize the physiologic and molecular events that accompany this syndrome.     

Stature estimation in ancient Egyptians: a new technique based on anatomical reconstruction of stature

Trotter and Gleser's (Trotter and Gleser: Am J Phys Anthropol 10 (1952) 469-514; Trotter and Gleser: Am J Phys Anthropol 16 (1958) 79-123) long bone formulae for US Blacks or derivations thereof (Robins and Shute: Hum Evol 1 (1986) 313-324) have been previously used to estimate the stature of ancient Egyptians. However, limb length to stature proportions differ between human populations; consequently, the most accurate mathematical stature estimates will be obtained when the population being examined is as similar as possible in proportions to the population used to create the equations. The purpose of this study was to create new stature regression formulae based on direct reconstructions of stature in ancient Egyptians and assess their accuracy in comparison to other stature estimation methods. We also compare Egyptian body proportions to those of modern American Blacks and Whites. Living stature estimates were derived using a revised Fully anatomical method (Raxter et al.: Am J Phys Anthropol 130 (2006) 374-384). Long bone stature regression equations were then derived for each sex. Our results confirm that, although ancient Egyptians are closer in body proportion to modern American Blacks than they are to American Whites, proportions in Blacks and Egyptians are not identical. The newly generated Egyptian-based stature regression formulae have standard errors of estimate of 1.9-4.2 cm. All mean directional differences are less than 0.4% compared to anatomically estimated stature, while results using previous formulae are more variable, with mean directional biases varying between 0.2% and 1.1%, tibial and radial estimates being the most biased. There is no evidence for significant variation in proportions among temporal or social groupings; thus, the new formulae may be broadly applicable to ancient Egyptian remains.