Use of Onlay Hydroxyapatite Cement for Secondary Cranioplasty.

BACKGROUND: Children who undergo bi-fronto-orbital advancement (BFOA) frequently develop a contour deformity on the temporal and supra-orbital region, with an incidence reported as high as 55% and 75%, respectively. Up to 20% of patients may require correction. Hydroxyapatite cement (HAC) is a good alternative to autogenous tissue. The available literature on its use focusses on the reconstruction of bone defects, but little has been published on its efficacy and safety as an onlay graft over intact cranium. OBJECTIVES: To describe our institution's experience with HAC in the pediatric population. METHODS: Retrospective chart review from 1998 to 2018 on all patients from the Craniofacial Unit at the Sydney Children's Hospital who had either coronal or metopic craniosynostosis and underwent BFOA and later in life required cranioplasty with HAC for contour repair. FINDINGS: We have performed 166 BFOA and nineteen secondary cranioplasties for contour repair using onlay HAC. The mean age at the time of operation was 14 years. Bi-coronal craniosynostosis was most frequently associated with secondary cranioplasty and 37% had an associated syndrome. The mean volume of HAC used was 37 mL. There was only 1 patient who had a complication (5.3%) and required partial removal of allograft. The mean length of admission was 2 days. Mean follow up time of 22.4 months. CONCLUSIONS: HAC represents a safe option when used correctly, with low rates of complication and satisfactory cosmetic outcomes.

A craniosynostosis massively parallel sequencing panel study in 309 Australian and New Zealand patients: findings and recommendations.

PURPOSE: The craniosynostoses are characterized by premature fusion of one or more cranial sutures. The relative contribution of previously reported genes to craniosynostosis in large cohorts is unclear. Here we report on the use of a massively parallel sequencing panel in individuals with craniosynostosis without a prior molecular diagnosis. METHODS: A 20-gene panel was designed based on the genes' association with craniosynostosis, and clinically validated through retrospective testing of an Australian and New Zealand cohort of 233 individuals with craniosynostosis in whom previous testing had not identified a causative variant within FGFR1-3 hot-spot regions or the TWIST1 gene. An additional 76 individuals were tested prospectively. RESULTS: Pathogenic or likely pathogenic variants in non-FGFR genes were identified in 43 individuals, with diagnostic yields of 14% and 15% in retrospective and prospective cohorts, respectively. Variants were identified most frequently in TCF12 (N = 22) and EFNB1 (N = 8), typically in individuals with nonsyndromic coronal craniosynostosis or TWIST1-negative clinically suspected Saethre-Chotzen syndrome. Clinically significant variants were also identified in ALX4, EFNA4, ERF, and FGF10. CONCLUSION: These findings support the clinical utility of a massively parallel sequencing panel for craniosynostosis. TCF12 and EFNB1 should be included in genetic testing for nonsyndromic coronal craniosynostosis or clinically suspected Saethre-Chotzen syndrome.

Thermoregulation, Not Just Camouflage: The Unique Vasculature of Giraffe Patches. A Cadaver Study with Clinical Implications.

BACKGROUND: Serendipitously, a dead giraffe provided opportunity to study its vascular anatomy. Comparative animal studies have revealed important information for designing new flaps and new microsurgical techniques. So, do giraffe's patches support a thermal window concept, do animals with similar markings and habitat have a similar thermoregulatory role, and could results offer new insight into human thermoregulation and free tissue transfer? METHODS: Previously described lead-oxide arterial-only injection studies, of a single giraffe, zebra, Africa wild dog, and spotted jaguar, all with wire-encircled pigmented patches; and archival human, pig, dog, cat, and rabbit studies, were compared. RESULTS: Each giraffe patch was supplied by just a single artery (angiosome) averaging 0.9 mm diameter, that divided near its center and sent dense, long, parallel, radiating spoke-wheel branches averaging 0.62 mm diameter to the patch margin, continuing as reduced-caliber choke anastomoses averaging 0.8 mm to link adjacent patch angiosomes. Uniquely arranged large veins, with an average of 1.66 mm, encircled the patches in the pale skin paralleled by arteriae comitantes averaging 0.22 mm. These arteries, connected to patch angiosomes, filled the veins intermittently by means of arteriovenous (A-V) shunts averaging 0.12 mm in diameter of magnitude never seen before in any species studied. None of the other three animals had angiosome territories matching their pigmented fur, or significant A-V filling. CONCLUSIONS: This study supports the "thermostatic" concept of the giraffe skin patches, with A-V shunts playing a major role. It affirms the need for further studies of these shunts in human thermoregulation and other flow regulations in physiology, pathology, and free tissue transfer.

Knotless Tendon Repair with a Resorbable Barbed Suture: An In-vivo Comparison in the Turkey Foot.

Background: Un-knotted barbed suture constructs are postulated to decrease repair bulk and improve tension loading along the entire repair site resulting in beneficial biomechanical repair properties. Applying this repair technique to tendons has shown good results in ex-vivo experiments previously but thus far no in-vivo study could confirm these. Therefore, this current study was conducted to assess the value of un-knotted barbed suture repairs in the primary repair of flexor tendons in an in-vivo setting. Methods: Two groups of 10 turkeys (Meleagris gallapovos) were used. All turkeys underwent surgical zone II flexor tendon laceration repairs. In group one, tendons were repaired using a traditional four-strand cross-locked cruciate (Adelaide) repair, while in group two, a four-strand knotless barbed suture 3D repair was used. Postoperatively repaired digits were casted in functional position, and animals were left free to mobilise and full weight bear, resembling a high-tension post-op rehabilitation protocol. Surgeries and rehabilitations went uneventful and no major complications were noted. The turkeys were monitored for 6 weeks before the repairs were re-examined and assessed against several outcomes, such as failure rate, repair bulk, range of motion, adhesion formation and biomechanical stability. Results: In this high-tension in-vivo tendon repair experiment, traditionally repaired tendons performed significantly better when comparing absolute failure rates and repair stability after 6 weeks. Nevertheless, the knotless barbed suture repairs that remained intact demonstrated benefits in all other outcome measures, including repair bulk, range of motion, adhesion formation and operating time. Conclusions: Previously demonstrated ex-vivo benefits of flexor tendon repairs with resorbable barbed sutures may not be applicable in an in-vivo setting due to significant difference in repair stability and failure rates. Level of Evidence: Level IV (Therapeutic).

Paediatric dog bite injuries: a 10-year retrospective cohort analysis from Sydney Children's Hospital.

BACKGROUND: Dog bite injuries are largely preventable yet present the most common animal related cause of hospitalisation. This study examines the demographics and clinical cost of patients with dog bite related injuries who presented to Sydney Children's Hospital (SCH) from 2010 to 2020. The results from our study will be used to raise awareness regarding the impact of dog bite injuries in our community. METHODS: Data was obtained from the SCH database using ICD-10-AM code W54.0, which captures all patients presenting to SCH with dog bite injuries from 2010 to 2020. A chart review was then performed to retrieve demographic data for analysis. Data analysis was performed using SAS® software version 9.4 and cost for each patient retrieved from the SCH clinical costing department. RESULTS: A total of 628 patients presented to SCH with dog bites during the study period. 273 (43.5%) patients received treatment in ED only with the remaining 355 (56.5%) patients admitted for treatment. The average age was 5.69 years old. There were 321 males (51.1%) and 307 females (48.9%). Facial and other head & neck injuries were most common (64.4%). Pitbull, Labrador and Rottweiler were the most commonly documented offending breeds (25%) with the family dog most likely to offend (49%). The mean clinical cost for per dog bite injury was $2968. CONCLUSION: As part of the largest single centre study exploring dog bite injuries, we expect that this study will stimulate potential public health campaigns targeted at educating parents and children on interacting with dogs to minimise these injuries.

Assessment of paediatric head shape and management of craniosynostosis.

BACKGROUND: The presentation of a child with an abnormal head shape can be challenging and should be met with an appropriate clinical approach. Craniosynostosis is a common cause of paediatric skull deformity and is best managed by a multispecialty tertiary referral unit with regular follow-up. As craniosynostosis frequently requires time-sensitive surgery, it is important to differentiate between craniosynostosis and common self-limiting conditions such as deformational plagiocephaly. OBJECTIVE: The aim of this article is to outline the clinical approach to paediatric skull deformity in the general practice setting, and to highlight the importance of early referral if there is clinical suspicion of craniosynostosis. DISCUSSION: Parental concern regarding infant head shape is common. General practitioners (GPs) have an important role in assessment, diagnosis and referral for paediatric skull deformities. GPs are well placed to clinically differentiate between deformational plagiocephaly and craniosynostosis and provide timely referrals to optimise patient outcomes.

Influence of locking stitch size in a four-strand cross-locked cruciate flexor tendon repair.

PURPOSE: The 4-strand cross-locked cruciate technique (Adelaide technique) for repairing flexor tendons in zone II is a favorable method in terms of strength and simplicity. The purpose of this study was to investigate the effects of varying the cross-lock stitch size in this repair technique. Outcomes measured were load to failure and gap formation. METHODS: We harvested 22 deep flexor tendons from adult pig forelimbs and randomly allocated them into 2 groups. After cutting the tendons at a standard point, we performed a 4-strand cross-locked cruciate repair using 3-0 braided polyester with either 2-mm cross-locks (n = 11) or 4-mm cross-locks (n = 11). All repairs were completed with a simple running peripheral suture using 6-0 polypropylene. Repaired tendons were loaded to failure and the mechanism of failure, load to failure, stiffness, and load to 2-mm gap formation were determined. RESULTS: All repairs failed by suture breakage; we noted no suture pullout. There was no difference in load to failure (71.7-71.1 N; p = .89) or stiffness (4.1-4.6 N/mm; p = .23) between the 2-mm cross-lock and the 4-mm cross-lock groups. There was a trend toward higher resistance to 2-mm gap formation with the 4-mm cross-locks (55-62.2 N; p = .07). CONCLUSIONS: Four-strand cross-locked cruciate repairs with cross-lock sizes of 2 and 4 mm provide high tensile strength and are resistant to pullout. Repairs with 4-mm cross-locks tend to provide a more central load distribution and better gapping resistance than repairs with 2-mm cross-locks.

Orbital emphysema following removal of bilateral midfacial implants.

A 36-year-old man with Crouzon syndrome was referred post-operatively with unilateral painful limitation of eye movements and proptosis following removal of bilateral malar and orbital rim implants. Further investigation revealed right inferior orbital emphysema, caused by the intra-operative entrance of hydrogen peroxide through a suspected perforation of the orbital septum. The symptoms settled with conservative management.

The removal of cranial springs used in the treatment of scaphocephaly: A minimal access approach.

The treatment of non-syndromic scaphocephaly with spring-activated cranioplasty offers acceptable outcomes with the potential for reduced surgical morbidity when compared with cranial vault remodelling procedures. A disadvantage of this technique is the need for a second operative intervention to remove the implanted devices. There are many descriptions of the surgical technique for performing spring-activated cranioplasty available in the literature; however, little is documented regarding the procedures used for device removal. The published accounts of spring removal demonstrate a wide range of approaches, from the reopening and dissection of the entire previous surgical field, to attempts to limit the incisions and dissection. In this study we describe our technique for the minimally invasive removal of cranial springs used in the treatment of scaphocephaly. Our technique focuses on minimal soft tissue disruption and uses a Kirschner wire cutter to divide the spring at its mid-point so as to relieve any residual internal forces acting on the footplates.

Quantification of Head Shape and Cranioplasty Outcomes: Six-compartment Volume Method Applied to Sagittal Synostosis.

BACKGROUND: Premature fusion of the sagittal (midline) suture between 2 parietal bones is the most common form of craniosynostosis. Surgical correction is mandated to improve head shape and to decrease the risk of raised intracranial pressure. This study evaluated the utility of 3-dimensional (3D) imaging to quantify the volumetric changes of surgical correction. Currently there is no standardized method used to quantify the outcomes of surgery for craniosynostosis, with the cranial index (width: length ratio) being commonly used. METHODS: A method for quantification of head shape using 3D imaging is described in which the cranium is divided up into 6 compartments and the volumes of 6 compartments are quantified and analyzed. The method is size invariant, meaning that it can be used to assess the long-term postoperative outcomes of patients through growth. The method is applied to a cohort of sagittal synostosis patients and a normal cohort, and is used to follow up a smaller group of synostotic patients 1, 2, and 3 years postoperatively. RESULTS: Statistical analysis of the results shows that the 6-compartment volume quantification method is more accurate in separating normal from synostotic patient head shapes than the cranial index. CONCLUSIONS: Spring-mediated cranioplasty does not return head shape back to normal, but results in significant improvements in the first year following surgery compared with the preoperative sagittal synostosis head shape. 3D imaging can be a valuable tool in assessing the volumetric changes due to surgery and growth in craniosynstosis patients.

In vitro comparison of lagged and nonlagged screw fixation of metacarpal fractures in cadavers.

PURPOSE: Lag screw fixation is reported to provide the most biomechanically stable construct for fixation of oblique or spiral metacarpal fractures. Lag screws are inserted after overdrilling the proximal cortex, resulting in compression at the fracture site. Minor drilling errors can result in poor screw purchase, instability, and ultimately impaired fracture healing. In an in vitro study, we compared construct stability provided by nonlagged and lagged screw fixation. METHODS: A cadaveric human metacarpal model was used. After removing the soft tissue, long oblique osteotomies were made in 24 metacarpals, which were then randomized to lagged or nonlagged fixation. Nonlagged fixation was performed through a newly introduced reduction system. Fixed specimens were subjected to biomechanical analysis by way of cantilevered bending to failure, and calculations were made for axial stress and normalized stiffness. RESULTS: All specimens failed in a typical manner through the proximal screw site. Nonlagged compared with lagged screw fixation resulted in a higher axial stress and normalized stiffness, although the differences did not reach statistical significance. CONCLUSIONS: Nonlagged screw fixation with use of a precompression device provided comparable fracture site stiffness and biomechanical stability without use of lag screws while removing the requirement for overdrilling, thus simplifying the technique.

Visual manifestations of craniofrontonasal dysplasia.

In this sample of craniofrontonasal dysplasia, a 44.4% prevalence of visual impairment was observed, with more than half being due to potentially correctable causes of visual loss, including amblyopia and anisometropia. High prevalences of strabismus (88.9%) and V-pattern (55.5%) in craniofrontonasal dysplasia were also demonstrated. All three patients who underwent strabismus surgery showed improvement in ocular alignment postoperatively. This group needs regular eye examinations to assess for visual impairment and provide timely intervention for modifiable causes of visual loss.

Animal Models for Tendon Repair Experiments: A Comparison of Pig, Sheep and Human Deep Flexor Tendons in Zone II.

BACKGROUND: This laboratory study compared pig, sheep and human deep flexor tendons in regards to their biomechanical comparability. METHODS: To investigate the relevant biomechanical properties for tendon repair experiments, the tendons resistance to cheese-wiring (suture drag/splitting) was assessed. Cheese-wiring of a suture through a tendon is an essential factor for repair gapping and failure in a tendon repair. RESULTS: Biomechanical testing showed that forces required to pulling a uniform suture loop through sheep or pig tendons in Zone II were higher than in human tendons. At time point zero of testing these differences did not reach statistical significance, but differences became more pronounced when forces were measured beyond initial cheese-wiring (2 mm, 5 mm and 10 mm). The stronger resistance to cheese-wiring was more pronounced in the pig tendons. Also regarding size and histology, sheep tendons were more comparable to human tendons than pig tendons. CONCLUSIONS: Differences in tendon bio-properties should be kept in mind when comparing and interpreting the results of laboratory tendon experiments.

The Interlocking Modification of the Cross Locked Cruciate Tendon Repair (Modified Adelaide Repair): A Static and Dynamic Biomechanical Assessment.

The 4-strand cross-locked cruciate flexor tendon repair technique (Adelaide technique) has been shown to have comparably high resistance to gap formation and ultimate tensile strength. This study aimed to determine whether an interlocking modification to the Adelaide repair would impart improved biomechanical characteristics. Twenty four sheep flexor tendons were harvested, transected and repaired using either standard or modified Adelaide techniques. Repaired tendons were cyclically loaded. Gap formation and ultimate tensile strength were measured. Additionally, suture exposure on the tendon surface was determined. There was a statistically significant increase in resistance to gap formation in the early phase of cyclic loading within the modified Adelaide group. In the later stages of testing no significant difference could be noted. The average final load to failure in the modified group was higher than the standard group but this did not achieve statistical significance. Interlocking suture techniques in four strand tendon repair constructs can improve gapping behavior in the early phase of cyclic loading.

Structural Failure Mechanisms of Common Flexor Tendon Repairs.

BACKGROUND: This study investigated the exact failure mechanisms of the most commonly used conventional tendon repair techniques. A new method, radiographing repair constructs in antero-posterior and lateral projections before and after tensioning was used. This allowed to precisely analyse failure mechanisms in regards to geometrical changes in all three dimensions. Additionally the biomechanical stability focusing on gapping was tested. METHODS: Sheep fore limb deep flexor tendons were harvested and divided in eight groups of ten tendons. Three common variants of the Kessler repair method and four common 4-strand repair techniques were tested. Additionally a new modification of the Adelaide repair was tested. RESULTS: Biomechanical testing showed no significant differences in gapping for the three tested 2-strand Kessler repair groups. Once a double Kessler or 4-strand Kessler repair was performed the stability of the repair improved significantly. Further significant improvements in biomechanical stability could be achieved by using cross locks in the repair like in the Adelaide repair method. Qualitative analysis using radiographs showed that all Kessler repair variants unfolded via rotations around the transverse suturing component, no matter which variant was used. CONCLUSIONS: Additional to the commonly described constriction of the repair construct, the rotating deformation is the main reason for repair site gapping in Kessler tendon repair methods. The term "locking" in a Kessler repair is misleading. The cruciate repairs tended to loose grip and drag (cheese-wire) through the tendon and therefore lead to gapping. The most stable repair constructs in all three dimensions were the Adelaide repair and its interlocking modification. This is due to the superior anchoring qualities of its cross locks and three dimensional stability.

Use of a polymeric device to deliver growth factors to a healing fracture.

BACKGROUND: Fracture healing is a cascade of events regulated by systemic and local factors. Local growth factors are believed to play an integral role. The present study evaluates the effects of basic fibroblast growth factor (bFGF) and insulin-like growth factor-1 (IGF-1) using a controlled delivery system in a closed rodent femoral fracture model. METHODS: Female Wistar rats (n = 144) were used in the present study. Animals were randomly allocated to six groups, with each group divided into three time-points of 2, 4 and 8 weeks. Two groups had growth factor administered. The others had no operation or sham operations. Growth factors were delivered to the fracture site using a specialised delivery system. This consisted of a Kirschner-wire coated with ethylene vinyl acetate co-polymer embedded with growth factors, inserted as an intramedullary nail. Fractures were effected with a three-point bending device. Femurs were tested in four-point bending and structural properties of peak load and stiffness were obtained from the load-displacement graphs. Specimens were prepared for qualitative analysis under a light microscope and using immunohistochemistry, specimens were analysed for expression of bFGF, IGF-1 and transforming growth factor beta (TGF-beta). RESULTS: The growth factor-treated groups exhibited larger calluses at 2 and 4 weeks. Four-point bending showed weaker structural properties (stiffness and peak load) at 4 weeks in both growth factor-treated groups. Administration of bFGF or IGF-1 increased the ratio of cartilaginous to mesenchymal tissues in the fracture callus compared with non-treated animals at 2 and 4 weeks. Immunostaining intensity and distribution of both growth factors in the treated groups was greater than the non-treated groups. CONCLUSION: Exogenous delivery of bFGF or IGF-1 alters the course of fracture healing.

Vascular anatomy of the medial sural artery perforator flap: a new classification system of intra-muscular branching patterns.

BACKGROUND: The medial sural artery perforator (MSAP) flap is a versatile fasciocutaneous flap. The main difficulty encountered when raising the MSAP flap is in obtaining adequate pedicle length during intra-muscular dissection. The objective of this study was to determine the pattern of intra-muscular course of the MSAP flap pedicle. METHODS: 14 cadaveric specimens were dissected and CT angiograms of 84 legs were examined. The intra-muscular branching pattern and depths of the medial sural artery branches were analyzed. The number of perforators, position of the dominant perforator and both intra-muscular and total pedicle length were also recorded and compared to existing anatomical data. RESULTS: Three types of arterial branching pattern were identified within the medial gastrocnemius, demonstrating one (31%), two (59%) or three or more (10%) main branches. A dominant perforator from the medial sural artery was present in 92% of anatomical specimens (13/14). Vertically, the location of the perforator from the popliteal crease was on average 13 cm (±2 cm). Transversely, the perforator originated 2.5 cm (±1 cm) from the posterior midline. Using CT angiography it was possible in 10 consecutive patients to identify a more superficial intra-muscular branch and determine the leg with the optimal branching pattern type for flap harvest. CONCLUSIONS: This study is the first to describe the variability of the intra-muscular arterial anatomy of the medial head of gastrocnemius muscle. Surgeons utilizing the MSAP flap option should be aware of the possible branching pattern types and consequently the differing perforator distribution and depths of intra-muscular branches. Routine use of pre-operative CT angiogram may help determine which leg has the most favorable branching pattern type and intra-muscular course for flap harvest.

The histology of facial aesthetic subunits: implications for common nasal reconstructive procedures.

Reconstruction of cutaneous nasal defects is often a challenging problem with multiple solutions. Many factors must be considered when deciding on the appropriate reconstructive procedure, including optimally matching donor site skin to the original recipient site skin. To the best of our knowledge no objective study has been undertaken to examine which areas best match the histological features of skin from various nasal cosmetic subunits. We have undertaken a descriptive histological analysis of skin from 25 facial and nasal aesthetic subunits from four male Caucasian cadavers, aged 65-88. The three variables looked at were epidermal thickness, dermal thickness and density of pilosebaceous subunits. Our findings have been plotted on photographs of the face to provide visual maps of facial histological features by cosmetic subunit. Our results show that histologically, the best matched skin for reconstructing a given nasal defect is likely to come from an adjacent nasal subunit. Looking at distant donor sites, the helical root, helical rim and pre-auricular area are closest to nasal skin in terms of dermal thickness. In terms of density of pilosebaceous units, the helical root, pre-auricular area and lateral forehead are the three areas best matched to nasal skin.

Stress relaxation and creep: viscoelastic properties of common suture materials used for flexor tendon repair.

PURPOSE: The time-dependent mechanical behavior of common suture materials may have a pronounced influence on the quality of flexor tendon repairs with respect to gap formation. METHODS: Sutures commonly used in plastic surgery, particularly for hand tendon repair, were tested in tension for analysis of stress relaxation and creep properties. The three materials tested were (1) Prolene, a monofilament polypropylene(Ethicon, Somerville, NJ); (2) Ethilon, a monofilament nylon(Ethicon, Somerville, NJ); and (3) Ticron, a braided polyester fiber (Sherwood, Davis & Geck, St. Louis, MO). All measurements were made with 1.5-mm (4-0) varieties of the sutures, in physiological buffered solution (0.9% phosphate-buffered saline [PBS]) at both room (22 degrees C) and body temperature (37 degrees C) conditions. RESULTS: Ticron was the stiffest suture at both room and body temperature, followed by Prolene and Ethilon. Both Prolene and Ethilon showed statistically (p< .05) reduced stiffness at body temperature. Prolene exhibited statistically larger (p< .05) relaxation and creep ratios than the other two sutures, and it was the only material to show temperature effects in creep and relaxation. CONCLUSIONS: Based on static and viscoelastic mechanical properties, Ticron is the most suitable suture for flexor tendon repairs when compared to Prolene and Ethilon.