Damir B. Matic

a Contraindication for the Use of Hydroxyapatite Cement in the Pediatric Population

&NA; The authors report on their experience with a particular hydroxyapatite cement in the pediatric population and review cases that elucidate potential limitations of its use in this population. In all patients, the implant was used for recontouring and augmenting the cranial vault. Seven of 15 patients had a direct communication between sinus mucosa and the implant at the time of surgery. Three of the seven patients developed late postoperative inflammatory reactions of the surgical site with delamination of the implant. Each patient required an aggressive irrigation and debridement with removal of the delaminated hydroxyapatite. Pathologic findings showed evidence of a foreign body inflammatory reaction in the tissue, and mixed bacterial flora were identified in all specimens. No late problems with the cement were seen in patients without a communication to the sinuses. Our findings suggest that the use of BoneSource, an essentially nonviable, nonvascularized implant, in areas exposed to bacterial contamination is contraindicated in the pediatric population. BoneSource and other similar hydroxyapatite biomaterials do have a role as implants in the craniofacial skeleton. The indications and contraindications of these substances will need to be further defined for wide acceptance to occur.

Biomechanical analysis of hydroxyapatite cement cranioplasty

A recent review of the authors’ experience with hydroxyapatite (HA) cement cranioplasties revealed a high infection rate. During removal of these implants, all were loose and fractured. Forty percent of these patients had a history of minor trauma at the site of cranioplasty before experiencing infection. Minor trauma may fracture HA cranioplasties and result in infection. The purpose of this study is to determine the force to fracture full- and partial-thickness cranial defects reconstructed with HA cement and to compare peak loads of differing HA cement cranioplasty techniques.Standardized craniotomy defects were created in five fresh cadaver heads. Full-thickness defects were reconstructed with either rigid or flexible titanium mesh and then covered with HA cement. Partial-thickness defects were reconstructed with HA alone. After setting, a uniaxial impact was delivered to each of the defects. Peak loads were recorded, and defects were examined for evidence of fracture.Predictable fractures of the HA cranioplasties occurred at 1200 N in all full-thickness defects reconstructed with mesh and a thin layer of HA. Implant loosening and chipping was similar to what was seen clinically in the authors’ patients with infections. Full-thickness defects in which titanium mesh was shaped like a cup and filled with a thick layer of HA resist fracture at 1200 N. Partial-thickness defects reconstructed with HA alone also do not fracture at this peak load.Patient selection, defect characteristics, and reconstructive techniques are factors that need to be considered before using HA cement for cranioplasty purposes.

The Anatomy of Temporal Hollowing: The Superficial Temporal Fat Pad

A coronal incision provides exposure to the lateral craniofacial skeleton for plastic surgeons, oral-maxillofacial surgeons, head and neck surgeons, neurosurgeons, and cosmetic surgeons. A common complication of this approach is hollowing of the temporal fossa. This hollowing results in a significant cosmetic deformity that affects the patient physically and psychologically. Current theories suggest that hollowing may result from atrophy of the superficial temporal fat pad caused by ischemia, displacement, or denervation of the fat pad. The purpose of this study is to identify the neurovascular supply and the supporting structures of the superficial temporal fat pad. Eight fresh-frozen cadaver heads were injected with latex to facilitate identification of vessels. Through coronal incisions, the anatomy of the vessels, nerves, and fascial network within the superficial temporal fat pads were recorded. The vascular supply of the superficial temporal fat pad includes branching perforators from the deep and middle temporal arteries that traverse through the substance of the fat pad. The branches of the zygomaticotemporal nerve travel through the superficial temporal fat pad. There is a network of septations that suspends the superficial temporal fat pad to the anterior fascia. This is the first step to understanding the etiology of postoperative temporal hollowing. This study provides the basis for a prospective randomized clinical trial investigating temporal hollowing after different surgical exposures of the area.

Evaluating the success of gingivoperiosteoplasty versus secondary bone grafting in patients with unilateral clefts.

Background: The role of gingivoperiosteoplasty in closure of the cleft alveolus remains controversial. Few studies have documented long-term results of gingivoperiosteoplasty and how it compares to secondary bone grafting. The purpose of this study was to compare gingivoperiosteoplasty with secondary bone grafting by evaluating the amount of bone produced at the alveolar cleft site in patients with unilateral clefts. This comparison should help delineate the role of gingivoperiosteoplasty in the management of patients with clefts. Methods: Eighty-six unilateral patients past the age of permanent canine tooth eruption with repaired alveolar clefts were identified. Clinical evaluations of the alveolar cleft site were performed. Grading for 73 periapical and occlusal films was recorded using the scales of Bergland, Long et al., and Witherow et al. and grouped according to gingivoperiosteoplasty (n = 64) or secondary bone grafting (n = 9). Results: The average patient age was 17 years. The clinical success rate of gingivoperiosteoplasty was lower than that of secondary bone grafting, 41 percent versus 88 percent, respectively. Radiologic evaluations showed that the gingivoperiosteoplasty group had a greater than 90 percent failure rate. In addition, patients in the gingivoperiosteoplasty group that had salvage bone grafting after failed gingivoperiosteoplasty (n = 19) still had less bone at the alveolar cleft compared with patients in the secondary bone grafting group. Conclusions: Gingivoperiosteoplasty resulted in bone of less quantity and poorer location within the alveolar cleft. Most unilateral clefts repaired with a gingivoperiosteoplasty will require additional bone grafting. Secondary bone grafting should continue to be considered the standard treatment.

Temporal hollowing following coronal incision: a prospective, randomized, controlled trial.

Background: Coronal incisions are used in traumatic, reconstructive, and cosmetic procedures to access the lateral facial skeleton. Temporal hollowing is a common complication following coronal incision that affects the patient both physically and psychologically. Several dissections have been recommended through this area to avoid injury to the frontal branch of the facial nerve and the temporal fat pad, which is thought to be the cause of hollowing. The purpose of this study was to identify the cause of postoperative temporal hollowing. Methods: Patients requiring a coronal incision were recruited prospectively. Each side of the head in all patients was randomized to suprafascial, subfascial, or deep dissection. An unmarked envelope containing the type of dissection to be performed for each side was used. All envelopes contained equal distributions of all groups. The incidence and severity of temporal hollowing 6 months postoperatively were measured clinically and by computed tomographic volume analysis. Results: Twenty-seven patients with 54 sides (18 suprafascial, 15 subfascial, and 21 deep) completed the study. There were no demographic differences among the three groups. The incidence and severity of temporal hollowing were lowest with suprafascial dissection. Other factors associated with the presence of temporal hollowing included a reduction in body mass index. There were no injuries to the frontal nerve in any of the dissections. Postoperative temporal hollowing was associated with surgical approach and postoperative weight loss. Conclusion: Elevation of a coronal flap in the suprafascial plane and minimization of patient weight loss may decrease the incidence of postoperative temporal hollowing.

The white-eyed medial blowout fracture.

Background: The pediatric white-eyed blowout fracture with entrapment of the inferior rectus muscle is well recognized as an easily missed injury with significant morbidity if left untreated. A series of five isolated medial orbital blowout fractures with medial rectus muscle entrapment is described. The purpose of this study was to define this injury pattern and its clinical outcome. Methods: A retrospective review of the presentation, management, and clinical outcomes of identified cases was conducted. Results: Early exploration and release of the entrapped muscle combined with implant reconstruction of the medial orbital wall within 2 weeks resulted in complete resolution of diplopia and full recovery of extraocular movements. Delayed treatment and release of the soft tissues without orbital wall reconstruction were associated with restricted gaze and diplopia. Similar outcomes were confirmed on analysis of other reported cases. Conclusions: Orbital floor blowout fractures in the pediatric population have a high incidence of muscle entrapment that must be recognized and treated early to avoid muscle necrosis and permanent ocular restriction from fibrosis. Medial orbital wall fractures with entrapment are rare, but early recognition and operative release of the entrapped muscles result in better outcomes.

The effects of botulinum toxin type A on muscle blood perfusion and metabolism.

Background: Botulinum toxin type A is approved by the U.S. Food and Drug Administration for the treatment of facial rhytides. However, the complete spectrum of action of botulinum toxin A has not yet been completely defined. Little is known about the metabolism of muscle after botulinum toxin A injection. This information may give insight into the additional effects botulinum toxin A may have on muscle. The authors assessed the influence of botulinum toxin A on the metabolism of muscle using dynamic investigative techniques. Methods: Twenty New Zealand White rabbits were divided into control, paralysis, and sham groups. Masseter muscle paralysis was achieved with botulinum toxin A. Dynamic computed tomographic and positron emission tomographic scans were obtained. Masseter muscle blood flow, blood volume, permeability surface, and mean transit time and glucose uptake were measured. Results: Eighteen animals completed the study. Masseter blood perfusion showed consistent results across all parameters. Blood flow, blood volume, and permeability surface were significantly increased at weeks 4 and 8 on the paralyzed side. Mean transit time at week 4 was decreased on the paralyzed side. Positron emission tomographic scans showed that injected muscles in the botulinum toxin A group tended to have increased glucose uptake compared with untreated muscles. Conclusions: Botulinum toxin A injection increases muscle blood perfusion parameters and glucose uptake for a transient period. This increase is similar in duration to the known interval of botulinum toxin A–induced paralysis. These changes have been identified in a dynamic fashion and may represent changes in calcitonin gene–related peptide release.

The Effects of Gingivoperiosteoplasty following Alveolar Molding with a Pin-Retained Latham Appliance versus Secondary Bone Grafting on Midfacial Growth in Patients with Unilateral Clefts

Background: Gingivoperiosteoplasty is used for early closure of the alveolar cleft in patients with complete clefts of the primary palate. However, its impact on long-term facial development remains unclear. The purpose of this study was to evaluate the effects of gingivoperiosteoplasty following alveolar molding with a pin-retained Latham appliance on long-term midfacial growth and compare it with secondary bone grafting. Methods: A retrospective review identified patients born with unilateral complete clefts of the primary and secondary palate. All patients were past the age of permanent canine tooth eruption. Standard cephalometric landmarks were plotted and analyzed by a blinded rater. Patients were divided into two groups based on type of alveolar closure: secondary bone grafting-only or gingivoperiosteoplasty-total. The gingivoperiosteoplasty-total group was further subdivided based on gingivoperiosteoplasty clinical outcomes. Statistical analyses first controlled for age and then for age and palate repair. Results: The average age of the patients was 14.7 years. Radiographs were obtained for 54 patients (gingivoperiosteoplasty-total, n = 38; secondary bone grafting-only, n = 16). The gingivoperiosteoplasty-total group demonstrated decreased maxillary height (p = 0.005) and protrusion (p = 0.001) versus secondary bone grafting only. Dentoalveolar occlusion was not statistically different between groups. Conclusions: Gingivoperiosteoplasty following alveolar molding with a pin-retained Latham appliance resulted in decreased maxillary protrusion and height compared with secondary bone grafting only. These differences were found irrespective of the technique of palatoplasty. This technique resulted in similar growth patterns as documented following primary bone grafting. Secondary bone grafting therefore remains the authors’ surgical approach to the cleft alveolus.

Rounding of the inferior rectus muscle as a predictor of enophthalmos in orbital floor fractures

In spite of established indications for early operative repair of orbital floor fractures 7-10% of patients treated nonoperatively develop enophthalmos. Clearly further indications for repair are required to prevent these post-injury complications. Rounding of the inferior rectus muscle on coronal computerized tomography (CT) scan results from a loss of soft tissue and bony support and may therefore be predictive of late enophthalmos. A four-year institutional review was conducted to identify patients with orbital floor fractures that had been treated nonoperatively. Patients were recruited for late clinical follow-up (mean 30 months) where clinically significant enophthalmos and diplopia were measured. Clinical results were correlated with measurements of the height-to-width ratio of the inferior rectus muscle on CT scans by a blinded examiner. Eighteen of 78 patients were available for late follow-up. Sixteen patients had no enophthalmos whereas 2 patients had enophthalmos. The inferior rectus height-to-width ratios measured in the unaffected orbits were statistically similar between the two groups. There was a significantly increased height-to-width ratio exceeding 1.00 in the affected orbit when the enophthalmos group was compared to the no enophthalmos group. A height-to-width ratio of the inferior rectus muscle on coronal CT scan of greater than or equal to 1.00 is predictive of late enophthalmos.

Gingivoperiosteoplasty following Alveolar Molding with a Latham Appliance versus Secondary Bone Grafting: The Effects on Bone Production and Midfacial Growth in Patients with Bilateral Clefts

Background: The role of gingivoperiosteoplasty in closure of bilateral alveolar clefts remains unclear. The purpose of this study was to evaluate bone production and midfacial growth in patients with bilateral clefts treated with gingivoperiosteoplasty following alveolar molding with a pin-retained Latham appliance versus secondary bone grafting. Methods: Patients with complete bilateral clefts past permanent canine eruption were included. Ethics approval and informed consent were obtained. Periapical films and lateral cephalograms were analyzed by one blinded rater based on three radiographic grading scales—Bergland, Witherow et al., and Long et al.—and standard cephalometric landmarks, respectively. Repeated measurements were recorded to assess intrarater reliability. Measurements were grouped according to gingivoperiosteoplasty versus secondary bone grafting and compared using parametric and nonparametric tests. Results: Fifty-three patients (gingivoperiosteoplasty, n = 43; secondary bone grafting, 10) met inclusion criteria. Average age was 15 years and 66 percent were male patients. Thirty-five patients had adequate radiographs for evaluation (gingivoperiosteoplasty, n = 25; secondary bone grafting, n = 10). Gingivoperiosteoplasty was clinically less successful than secondary bone grafting, 58 percent versus 90 percent, respectively. The quantitative radiographic success rate of gingivoperiosteoplasty, however, was 28 percent. Secondary bone grafting demonstrated higher Bergland, eight-point, and location grading (p < 0.002), and less alveolar notching (p = 0.008). Anteroposterior maxillary and mandibular dimensions were significantly decreased for the gingivoperiosteoplasty group versus the secondary bone grafting group. Conclusions: Bone quantity and location were inferior following bilateral gingivoperiosteoplasty versus secondary bone grafting, and the majority of patients required subsequent bone grafting. The gingivoperiosteoplasty group had decreased maxillary growth with mandibular compensation. Secondary bone grafting therefore remains our first choice for repair of bilateral alveolar clefts.