In situcranioplasty with methylmethacrylate and wire lattice

A new technique for preparing cadavers using PMMA: Rat and mouse example

BACKGROUND

Polymethyl methacrylate is a member of the acrylic polymer family with superior optical properties. It is used in dentistry, hospital incubators, lenses, and various surgical fields, especially orthopedics. In this preliminary study, we aimed to prepare cadavers using the industrial form of polymethyl methacrylate.

METHODS

The new technique consists of fixation, washing, purification, impregnation, and polymerization. For the study, two whole rat bodies, two rat front legs and two rat hind legs, one half rat body, two whole mouse bodies, and all internal organs were used. Wistar albino rats and BALB/c mice were used. After the cadaver samples were fixed and washed, they were passed through an alcohol series starting from 50%, completing the purification process. In the next step, a solution was prepared by mixing 100 ml of Thinner into 1000 ml of a mixture containing styrene, methyl methacrylate, and Co(II)2-ethyl hexanoate. The samples were immersed in the solution under negative pressure (from 10 mmHg to 400 mmHg), allowing the samples to absorb the solution thoroughly. They were then treated with methyl ethyl ketone peroxide and the polymerization step was terminated.

RESULTS

The cadaver samples obtained using polymer were hard, they maintained the given shape, and showed a relatively transparent quality. The production of these materials took 35 days, excluding fixation. The tissue samples were odorless in the process after polymerization. Also, there was no decay in the samples after the production stage and they could be stored under room conditions.

CONCLUSION

This study determined that cadavers could be prepared using polymethyl methacrylate and methyl ethyl ketone peroxide. The polymer used here cost about $5. The cadavers can be safely exhibited in room conditions for five years without requiring special conditions like pools or cold storage. Further research should compare this technique with the plastination technique in terms of texture, color, weight, application time, and cost.

Materials and techniques used in cranioplasty fixation: A review

Cranioplasty is the surgical repair of a deficiency or deformity of the skull. The purpose of cranioplasty is to provide protection for the brain following cranial surgery, and to offer relief to psychological disadvantages while increasing social performance. There are several materials that had been used for cranioplasty but an ideal product has yet to be developed, hence the ongoing research into biologic and non-biologic alternatives to the existing materials. This article critiques the products currently used for cranioplasty in order to facilitate the development of new materials, which can improve patient outcomes.

Glass Polyalkenoate Cements Designed for Cranioplasty Applications: An Evaluation of Their Physical and Mechanical Properties

Glass polyalkenoate cements (GPCs) have potential for skeletal cementation. Unfortunately, commercial GPCs all contain, and subsequently release, aluminum ions, which have been implicated in degenerative brain disease. The purpose of this research was to create a series of aluminum-free GPCs constructed from silicate (SiO₂), calcium (CaO), zinc (ZnO) and sodium (Na₂O)-containing glasses mixed with poly-acrylic acid (PAA) and to evaluate the potential of these cements for cranioplasty applications. Three glasses were formulated based on the SiO₂-CaO-ZnO-Na₂O parent glass (KBT01) with 0.03 mol % (KBT02) and 0.06 mol % (KBT03) germanium (GeO₂) substituted for ZnO. Each glass was then mixed with 50 wt % of a patented SiO₂-CaO-ZnO-strontium (SrO) glass composition and the resultant mixtures were subsequently reacted with aqueous PAA (50 wt % addition) to produce three GPCs. The incorporation of Ge in the glass phase was found to result in decreased working (142 s to 112 s) and setting (807 s to 448 s) times for the cements manufactured from them, likely due to the increase in crosslink formation between the Ge-containing glasses and the PAA. Compressive (σc) and biaxial flexural (σf) strengths of the cements were examined at 1, 7 and 30 days post mixing and were found to increase with both maturation and Ge content. The bonding strength of a titanium cylinder (Ti) attached to bone by the cements increased from 0.2 MPa, when placed, to 0.6 MPa, after 14 days maturation. The results of this research indicate that Germano-Silicate based GPCs have suitable handling and mechanical properties for cranioplasty fixation.

In Situ Cranioplasty for Hyperostosing Meningiomas of the Cranial Vault

Objective:

Hyperostosis of the bone overlying meningiomas has been reported in up to 50% of cases. The skull becomes infiltrated by meningothelial tumor cells, necessitating removal of the hypertrophied bone to achieve a complete tumor resection. Unfortunately, aesthetic reconstruction of large bony defects can pose a significant challenge intra-operatively. Custom cranioplasty implants are very expensive and can only be fabricated after the bony defect exists, requiring a second surgery for implantation. Although numerous composite materials exist to repair the defects at the time of tumor resection, the challenge is to create an implant that fits appropriately without shifting and approximates the natural curvature of the skull. We have developed a technique for an “in situ cranioplasty” using a composite construct with strength in compression and tension.

Technique:

After the skull is reshaped by shaving down part of the hyperostotic bone, titanium mesh is molded to the surface of the skull and screwed into the surrounding normal bone. The bone flap is then removed by drilling a trough at the outer margin of the tumor-involved skull and removing a ring of normal surrounding bone. The central portion of tumor involved skull is then craniectomized. The mesh can be reapplied and the full thickness of the central bone can be reconstructed with polymethylmethacrylate, yielding a solid construct perfectly matched to the patient's natural head shape.

Conclusion:

This novel technique yields a sturdy, aesthetic, and cost-effective result which can be used to address any cranial vault defect at the time of tumor resection.

Role of a dentist in comprehensive management of a comatose patient with post traumatic head injury and neuropathological chewing

Injury of the head and neck region can result in substantial morbidity. Comprehensive management of such patients requires team work of several specialties, including dentists. A young female patient with extensive loss of cranium and associated pathological chewing was referred to the dental department. The lost cranium was replaced by a custom-made, hand-fabricated cranioplast. Trauma due to pathological mastication was reduced by usage of a custom-made mouthguard. Favorable results were seen in the appearance of the patient and after insertion of the mouthguard as evidenced in good healing response. The intricate role of a dental specialist in the team to manage a patient with post traumatic head injury has been highlighted. The take away message is to make the surgical fraternity aware of the scope of dentistry in the comprehensive management of patients requiring special care.

Acrylic cranial implant: an alternative vector in management of cranial defect

In a pediatric patient with cranial defect, in order to replace the missing portion of the cranium, an acrylic cranial implant was fabricated prior to the surgical procedure. The primary aim was to fabricate this cranial implant prior to the surgical procedure and with optimum fit. A customized hand-sculpted acrylic cranial implant fabricated by lost wax technique was made prior to the surgery and with adequate precision.The prefabricated cranial implant was used by neurosurgeons on the patient in order to restore the continuity of bone (by the acrylic cranioplast) over the cranial defect, improving the aesthetics and more importantly providing protection to the vital neural tissue.Though with recent advancements (like computer-aided design and manufacturing, and rapid prototyping), rapidity and precision can be achieved in the fabrication of cranial prosthesis, yet most of the apparatus may not be amenable in every setup and may not be affordable by all patients. A simple, operator-friendly technique which acquires satisfactory precision has been described for a patient much in need. Optimal postoperatory results were attained.

Temperature elevation during simulated polymethylmethacrylate (PMMA) cranioplasty in a cadaver model

The aims of this study were to: (i) obtain temperature measurements during in vitro polymerisation of polymethylmethacrylate (PMMA) disks of a range of thicknesses; and (ii) obtain tissue temperature measurements at various locations within a skull defect during a simulated PMMA cranioplasty procedure using a cadaver. In vitro, higher temperatures were recorded with increasing PMMA thickness. During the simulated cranioplasty, the maximum temperature was observed inside the PMMA sample, with nearby tissues being exposed to temperatures of greater than 50 degrees C over prolonged periods. There is conflicting information in the literature concerning the sensitivity of brain tissue and bone to elevated temperatures. Preoperatively fabricated PMMA cranioplasty prostheses are recommended.

Complications of cranioplasty following decompressive craniectomy: analysis of 62 cases

Object

Decompressive craniectomy is a potentially life-saving procedure used in the treatment of medically refractory intracranial hypertension, most commonly in the setting of trauma or cerebral infarction. Once performed, surviving patients are obligated to undergo a second procedure for cranial reconstruction. The complications following cranial reconstruction are not well described in the literature and may very well be underreported. A review of the complications would suggest measures to improve the care of these patients.

Methods

A retrospective chart review was undertaken of all patients who had undergone cranioplasty during a 7-year period. Demographic data, indications for craniectomy, as well as preoperative, intraoperative, and postoperative parameters following cranioplasty, were recorded. Perioperative and postoperative complications were also recorded. Patients were classified as having no complications, any complications, and complications requiring reoperation. The groups were compared to identify risk factors predictive of poor outcomes.

Results

The authors identified 62 patients who had undergone cranioplasty. The immediate postoperative complication rate was 34%. Of these, 46 patients did not require reoperation and 16 did. Of those requiring reoperation, 7 were due to infection, 2 from wound breakdown, 2 from intracranial hemorrhage, 3 from bone resorption, and 1 from a sunken cranioplasty, and 1 patient's cranioplasty procedure was prematurely ended due to intraoperative hypotension and bradycardia. The only factor statistically associated with need for reoperation was the presence of a bifrontal cranial defect (bifrontal: 8 [67%] of 12, requiring reoperation; unilateral: 8 [16%] of 49 requiring reoperation; p < 0.01)

Conclusions

Cranioplasty following decompressive craniectomy is associated with a high complication rate. Patients undergoing a bifrontal craniectomy are at significantly increased risk for postcranioplasty complications, including the need for reoperation.