Comparison of hydroxyapatite granules to autogenous bone graft in fusion cages in a goat model

BACKGROUND: With the increased use of fusion cages to achieve lumbar intervertebral fusion, the question arises as to the potential for bone ingrowth from the host bone through the entire cage. Is it even necessary to have an autogenous graft to achieve total bone incorporation? METHODS: Nine adult male goats had fusion cages implanted into three vertebral bodies. The design was Surgical Dynamics/Ray Fusion Cage, measuring 21 mm x 14 mm. In each animal, one fusion cage was filled with autogenous graft, one with hydroxyapatite, porous granules, and the other with nonporous granules. Amount of new bone formation was determined by backscatter electron microscopy at 3 months post implantation in all animals. RESULTS: The histologic section shows that there was total incorporation in all specimens at 3 months. There was slightly more new bone (43%) with the nonporous granules compared with the porous granules (35%). The amount of residual void space was about the same in all specimens, indicating that the amount of new bone formation was similar and not statistically different in cages filled with hydroxyapatite granules versus granules of autogenous bone. CONCLUSION: This study confirms that total incorporation by ingrowth of new bone can be expected in fusion cages. The amount of ingrowth is about the same for autogenous graft versus hydroxyapatite granules. Apparently, it is not necessary to use bone graft to achieve successful bone incorporation if an acceptable biocompatable lattice, such as hydroxyapatite granules, is used.     

Iatrogenic arachnoid cyst with distinct clinical picture as a result of bone defect in the floor of the middle cranial fossa: case report

OBJECTIVE AND IMPORTANCE: This kind of arachnoid cyst has not previously been described as a complication of a cranial base bone defect. Recognition of this rare complication may be delayed, because clinicians are unaware of its possibility. CLINICAL PRESENTATION: A 22-year-old man presented with severe headache and increasing difficulty in breathing and swallowing. A physical examination revealed a pulsatile mass in the oral cavity, arising from the parapharyngeal area. A cystic mass that protruded into the oral cavity, through a dural and bony defect in the left middle fossa, was detected on neuroimages. INTERVENTION: A left frontotemporal craniotomy was made, and the cyst was decompressed. Duraplasty was performed with lyophilized dura. The bone defect was managed with a calvarial free bone graft and a pedicled myofacial flap. Serial neuroimaging studies performed postoperatively showed that the cyst had decreased in size. CONCLUSION: This report describes an unusual complication of a cranial base bone defect. Although not all bone defects in the cranial base require reconstruction, management of the large bone defect, particularly in the middle fossa, should preferably be accomplished with the help of a bone graft to support the dural graft.     

Implementation of new technologies in cytotechnology education

INTRODUCTION: Current cranioplasty materials include autologous or homologous bone grafts, wire mesh and methyl methacrylate, either alone or in combination. However, each material has its own unique disadvantages. Although hydroxyapatite has been used extensively in other specialties as a bone substitute, the coralline form has rarely been used to repair cranial bone defects. Coralline hydroxyapatite, similar to that found in bone, provides a matrix on which living tissue can form and grow. Because it is an ideal bioimplant, a method of cranioplasty using coralline hydroxyapatite was employed. METHODS: The hydroxyapatite granules are mixed with Avitene and autologous blood to form a paste which can be contoured as needed. RESULTS: Over the past few years, we have used hydroxyapatite either alone or in combination with tantalum mesh in 19 pediatric patients for a variety of conditions. The cosmetic results were good to excellent. Furthermore, postoperative CT scans have documented bony substitution of the hydroxyapatite granules. Follow-up ranged from 1 to 43 months with a mean of 26 months. CONCLUSION: In neurosurgical procedures when a bone substitute is needed, hydroxyapatite is an effective alternative to other currently available materials.     

Alternative treatments for a traumatic bone cyst: a longitudinal case report

A patient presented with a large, multilocular, refractory traumatic bone cyst. The radiolucency had increased in dimension since her last recall. Over 11 years, therapy had included needle aspiration biopsies followed by simple curettage and closure, the most common therapy for traumatic bone cysts. However, all treatment had proved unsuccessful for this patient. It was decided to treat the patient with a slightly unique method. After curettage of the lesion, the traumatic bone cyst was packed with a mixture of autogenous blood, harvested autogenous bone chips, and hydroxyapatite.     

Development of a nurse-managed, school-based health center

Discusses the possibility of using dense unresorbable hydroxyapatite (HA) ceramics as synthetic osteoplastic material. Analyzes the results of follow-up of 11 patients with congenital and posttraumatic deformations of the facial skull. Interventions in these patients involved implantation of HA-based ceramic blocks used for both contour plasty and for replacing bone defects. Describes methods of surgery with combined use of HA implants and fixing devices from titanium which serve to fix bone fragments and ceramic blocks.     

Repair of bone defect in primate mandible using a bone morphogenetic protein (BMP)-hydroxyapatite-collagen composite

The purpose of this study was to evaluate a hydroxyapatite (HA)-collagen (Col)-bone morphogenetic protein (BMP) composite as an osteoinductive bone substitute. Partially-purified BMP from bovine bone was mechanically mixed with highly purified type I collagen from calf dermis and then subsequently mixed with pure synthetic hydroxyapatite granules or block. The HA-Col-BMP composite, or the HA-Col composite as a control, was implanted in a surgically-induced mandible bone defect (6 x 7 x 10 mm) in an adult Japanese monkey. The mandible was excised three months after implantation and studied histologically. The BMP-containing implant induced much more new bone than the control implant in all experimental animals of each group, with either HA granules or HA block. Newly formed bone was attached tightly to HA and infiltrated deeply into the pores of the HA of the BMP-containing implant, while fibrous tissue existed between the host bone and HA in the control implant. Thus, we conclude that an HA-Col-BMP composite could be a superior biomaterial for a bone substitute.     

Interesting case no. 10. Cholesteatoma with destruction of the sigmoid sinus after thrombosis, with epidural abscess and Benzold abscesses

We employed hydroxyapatite (HA) granules to enhance screw fixation in revision surgery of failed osteosynthesis with a compression hip screw system in an 83-year-old woman. After reduction of the fracture, the fracture site with a large bone defect was filled with HA granules, and osteosynthesis was accomplished with a double cannulated lag screw and plate system. We feel that this HA granule augmentation method may also be suitable for osteosynthesis in other osteoporotic fractures.     

Repair of the anophthalmic cavity of rats with synthetic hydroxyapatite

We placed spheres of synthetic hydroxyapatite (calcium chloride combined with sodium phosphate) in the eviscerated or enucleated orbital cavity of rats in order to evaluate the biocompatibility of this material with the orbital cavity. The study was conducted on 50 albino rats, 25 of which were submitted to enucleation and 25 to evisceration of one eye. The animals were sacrificed 7, 15, 21, 30 and 60 days after surgery and the orbital content was submitted to histopathological examination. A reaction of the young granulation tissue type was observed first. The hydroxyapatite was gradually surrounded by a granulomatous macrophage inflammatory response and covered with dense connective tissue that formed a sort of "mesh" septating and supporting progressively smaller blocks of the substance. The same type of reaction was observed in the enucleated and eviscerated cavities. We conclude that synthetic hydroxyapatite is an inert nonallergenic material which is appropriate for volume replacement in the anophthalmic cavity.     

Comparative analysis of interleukin 15 and interleukin 2 for induction of killer activity and of type 2 cytokine production by mononuclear cells from lung cancer patients

Simple bone cyst (SBC) is a benign fluid-filled cavity found primarily at the proximal ends of long bones in children. Treatments proposed for SBC range from observation to intralesional curettage and bone grafting, which are all associated with uncertainty and complications. Because of these factors, a relatively noninvasive protocol with osteoinductive autogenic bone marrow was instituted. Twelve patients were identified with SBCs. Bone marrow was aspirated from the patient's iliac crests and injected into the cyst cavity. Follow-up ranged from 9 to 57 months. Eight (67%) patients demonstrated substantial healing, two (17%) showed partial healing, and two (17%) did not respond to bone marrow therapy. The advantages suggested by bone marrow injection over the currently practiced methods include a higher success rate with a single injection and earlier healing.     

Congenital mediastinal bronchogenic cyst with malignant transformation: an autopsy report

A rare autopsy case of mediastinal bronchogenic cyst with malignant transformation is presented. The cyst had been located in the anterior mediastinum for at least 28 years in a 52 year old male. Chest X-ray findings showing rapid enlargement of the cyst and biopsy of the spine for lumbago made a clinical diagnosis as suspicious mediastinal cystic teratoma with malignant transformation metastasizing to the spine. Postmortem examination revealed that the cyst was located in the anterior mediastinum extending to the left pulmonary hilum and had no connection with the tracheobronchial tree. The cyst wall consisted of bronchus-like tissue including ciliated epithelium, hyaline cartilage, smooth muscle and mucoserous glands. There were no teratomatous components in the wall. Malignant tumor predominantly consisting of round cells occurred in the thickened cyst wall and grew into the cyst cavity with direct invasion of the lung and metastases to the liver, adrenal glands, bone marrow of the lumbar spine and lymph nodes. An immunohistochemical study showed that the tumor cells frequently expressed cytokeratin, epithelial membrane antigen and carcino-embryonic antigen, occasionally CA19-9, vimentin and neuron-specific enolase. From these findings, the tumor was diagnosed as undifferentiated carcinoma arising in the mediastinal bronchogenic cyst.     

Ruptured thymic cysts with mediastinal hemorrhage and hemothorax--a case report and reviews of the literature

We report a rare case with rupture of thymic cyst including mediastinal hemorrhage and hemothorax. A 68-year-old man was referred to our hospital for the treatment of right hemothorax. A chest roentgenogram following thoracentesis demonstrated a widened mediastinum. Chest computed tomograms revealed a large anterior mediastinal mass extending to the right pleural cavity and bilateral pleural effusion. Digital subtraction angiography showed a normal aorta and great vessels. A median stenotomy revealed a large encysted hematoma along the thymic cyst extending from the right anterior mediastinum into the right pleural cavity and ending with rupture. Pathological examination demonstrated that the largest thymic cyst was continued to the hematoma resulting from partial destruction of its epithelial lining. To our knowledge, only five cases including our's with ruptured thymic tumors were reported, and this is the first report of ruptured thymic cyst resulting in mediastinal hemorrhage and hemothorax.     

Histological comparison of early wound healing following dense hydroxyapatite granule grafting and barrier placement in surgically-created bone defects neighboring implants

The purpose of this study was to examine early wound healing following grafting of dense hydroxyapatite granules (HA granules) and barrier placement in surgically-created bone defects surrounding implants. Eight healthy adult dogs with an average weight of 15 kg were used in this study. Thirty-two bone defects measuring 4 mm x 4 mm were removed with a surgical bur to form continuous bucco-lingual bone defects and 32 implants (16 titanium [Ti]) and 16 hydroxyapatite-coated [HA]) were then placed into the defects. Four implant groups were created: 1) grafting HA; 2) covering with an expanded polytetrafluoroethylene (ePTFE) membrane; 3) grafting HA and covering with ePTFE membrane; and 4) control (no treatment). Animals were sacrificed 28 days after surgery. Histological sections revealed large amounts of newly-formed bone in all bone defects surrounding the implants treated with ePTFE membranes alone. Fibrous encapsulation of HA granules was observed in the defects of the HA granules grafting group. In the group with grafting of HA granules and covering with ePTFE membranes, small amounts of bone tissue were observed among HA granules, but most HA granules were surrounded with fibrous tissue. Bone defects were completely filled with connective tissue in the control group. There were no differences in the histological findings between Ti and HA-coated implants in all cases. Histomorphometric data disclosed that the presence of HA granules in the bone defects significantly arrested bone formation. Our study suggests that the grafting of dense HA into bone defects surrounding implants will result in fibrous healing during the early healing stage.     

Bladder cancer in a patient on long-term haemodialysis

OBJECTIVE: The results of the first cohort of 60 cavity reconstructions with hydroxyapatite with a minimum follow-up period of 15 years were studied. STUDY DESIGN: The study design was a retrospective study. PATIENTS: A total of 60 patients had a follow-up period of >15 years. In four patients, not all data were available. Therefore, 56 patients were included in the study. They had a combination of cavity problems and hearing loss. INTERVENTION: The ear canal was reconstructed with a canal wall prosthesis of porous hydroxyapatite. The ossicular chain was reconstructed with an incus or incus-stapes prosthesis of dense hydroxyapatite. RESULTS: After 15 years, 42 patients (75%) had an intact reconstructed ear canal. The main problem for failure was the recurrent purulent middle ear infection and not cholesteatoma. The histology of the retrieved canal wall showed a good remodeling in living bone tissue. After 15 years, 34 patients had a normal ear canal and an ossicular chain. Of these patients, 7.05% had an air-bone gap closure within 20 dB. CONCLUSIONS: Long-term results of cavity reconstruction with hydroxyapatite are possible. The main problem is recurrent mucosal disease of the new middle ear-mastoid cleft.     

Pigmented epidermal cyst

A 58-year-old Japanese woman with a pigmented epidermal cyst on the upper arch of the right external ear is described. The blue appearance of the cyst was striking and uncommon in Japanese. Histologically, abundant melanin pigment was observed in the keratinous mass of the cavity, and epithelial cells showed epidermoid keratinization. Increased numbers of melanocytes in the basal layer, large globular cells of melanocytic origin in the spinous layer, and hair-germ-like aggregates of basaloid cells and melanocytes were also observed. The blue clinical appearance is probably due to the rich melanin granules in the cyst, keratinous mass, keratinocytes, and hair-germ-like structures.     

Radical prostatectomy and prognostic factors

We investigated ectopic bone formation by biphasic calcium phosphate (BCP) combined with recombinant human bone morphogenetic protein-2 (rhBMP-2) in the rat dorsum. Under reduced pressure, rhBMP-2 was adsorbed onto BCP, which consisted of 80% beta-tricalcium phosphate and 20% hydroxyapatite uniformly distributed in granules. Twenty Wistar rats were separated into 4 groups consisting of 5 animals each dosed with 2, 10, and 50 micrograms/700 microliters of rhBMP-2 and a control group (BCP only). Pieces of the BCP-BMP complex or only BCP were implanted under the dorsal skin of the rats. Histological sections were examined three weeks later. New bone was formed in all rats given 50 micrograms doses, but not in the 2 micrograms and control groups. These results indicated that BCP combined with rhBMP-2 induced ectopic bone formation without additional carriers. Therefore, BCP granules alone can function as carriers for rhBMP-2 to induce bone formation.     

The outcome of adjusted accumulation dose of treatment of Graves'' disease

Etiology of syringomyelia associated with Chiari type I malformation has been unknown. Moreover, the surgical procedure of foramen magnum decompression for this type of syringomyelia has not been standardized yet. No one procedure has been always successful, leading to many alternative procedures. The purpose of the present study is to elucidate pathway of cerebrospinal fluid into the syrinx cavity and to find out the best procedure for this disease. Fourty two patients with syringomyelia associated with Chiari type I malformation, which were diagnosed with magnetic resonance imaging (MRI), underwent surgical treatment. In all patients, craniocervical junction anomalies, cervical disc herniation and other spinal diseases were ruled out. There were 26 men and 16 women, ranging from 6 to 72 (mean: 42.3) years in age. The size, length and position of upper end of each syrinx cavity and the degree of the tonsillar herniation were measured on preoperative T1-weighted image and were compared each other. There were no significant relationship between the degree of tonsillar herniation and the size, length and position of syrinx cavity. No case showed that the upper end of syrinx cavity communicated to the 4th ventricle. The results suggest that the pathway of cerebrospinal fluid into the the syrinx cavity was not central canal from the 4th ventricle but microcanals in the spinal cord. All patients were carried out with foramen magnum decompression, which was divided into 4 groups according to the degree of decompression: 1) tonsillectomy group: 12 patients underwent subocciptital craniectomy (SOC) with patcy-graft dural plasty using lyophilized dura mater and tonsillectomy, 2) lysis group: 7 underwent SOC, dural plasty and microsurgical lysis of arachnoidal trabecula and fibrinoid filament around herniated tonsil, 3) plasty group: 17 underwent SOC and dural plasty and 4) dural group: 6 underwent SOC and removal of the outer layer of the dura mater. The mean follow-up periods were 3.7 years in tonsillectomy group, 3.6 years in lysis group, 2.3 years in plasty group, 1.8 years in dural group, respectively. Evaluation of the result following four types of surgical treatments was performed on clinical symptoms and the volume of syrinx cavity on sagittal MRI. The ratio in the area of the syrinx and spinal cord on preoperative and postoperative sagittal MRI were measured. There was no significant difference among 4 groups on the degree of reduction of syrinx in the sagittal plane as evaluated on MRI, whereas with regards to improvement of the clinical symptoms, dural group was significantly worse than the other three groups. The surgical procedure of dural plasty was clearly less invasive than those of tonsillectomy and lysis of subarachnoidal trabecula. These results suggest that we should select dural plasty as a primary surgical procedure for syringomyelia associated with Chiari type I malformation.     

Vicryl-mesh wrap for the implantation of hydroxyapatite orbital implants: an animal model

OBJECTIVE: To evaluate host fibrovascularization of hydroxyapatite orbital implants wrapped in sclera or in Vicryl (polyglactin 910) mesh in a rabbit model. NUMBERS: Eight adult New Zealand white rabbits that received hydroxyapatite orbital implants wrapped in homologous donor sclera (four animals) or Vicryl mesh (four animals). INTERVENTIONS: The rabbits had one eye enucleated and then received a 12-mm hydroxyapatite implant wrapped in sclera or Vicryl mesh. Magnetic resonance imaging (MRI) and bone scintigraphy were done to assess host fibrovascularization of the implant 4, 8, 12 and 20 weeks after implantation. Two animals (one in each group) were killed at each of these times, and the implant was removed for histopathological examination. MAIN OUTCOME MEASURES: Enhancement on MRI, uptake on bone scintigraphy, fibrovascularization seen on histopathological examination. RESULTS: The degree of fibrovascularization was substantial in all the specimens but appeared greater in the Vicryl-mesh-wrapped implants in the first 12 weeks after implantation on both histopathological and MRI studies. At 20 weeks these findings were similar in the two groups. A granulomatous foreign-body giant-cell reaction to both the Vicryl mesh and the implant itself was present up to 8 weeks after implantation. Bone scans showed only grade 1+ activity in all the implants. CONCLUSIONS: Host fibrovascularization in the rabbit appears to occur to a greater degree in Vicryl-mesh-wrapped hydroxyapatite implants than in those wrapped in donor sclera during the first 12 weeks after implantation. Vicryl mesh appears to be an acceptable alternative wrap for the hydroxyapatite implant, eliminating the need for donor sclera and its potential risks of transmissible diseases.     

A case of fibromatosis needed reconstruction of the chest wall for postoperative local recurrence

The case was a sixty-four-year-old female with a history of fibrous tumor in the right supraclavicular and neck region thirty years ago. A fibrous tumor developed in the right pleural cavity and was surgically resected. Since local recurrence occurred, the chest wall was partially resected including the tumor followed by reconstruction with a composite graft. This graft was made of hydroxyapatite filler wrapped with two sheets of Dacron fabric. A diagnosis of fibromatosis was made according to the study of the resected specimen, which showed unclear borders, homogenisity, poor evidence of nuclear atypia and mitosis in histological examination as well as negative finding of CD 34 in immunohistochemical examination.     

Induced healing of aneurysmal bone cysts by demineralized bone particles. A report of two cases

Two cases of induced healing of aneurysmal bone cyst (ABC) following intralesional implantation of a bone paste made of autogeneic bone marrow and allogeneic bone powder are reported. The calcaneum in one case and the superior pubic ramus in the other were blown out by an ABC and would have required extensive surgery. Via a minimal exposure, the cyst was partially evacuated and filled with an admixture of a partially demineralized bone particles with bone marrow. Ossification of the peripheral shell was the first sign of healing and was observed within the first 3 postoperative months. Successful healing was observed in both cases. The rationale underlying this intralesional treatment was that the bone grafting material might reverse ABC expansion by promoting ossification through a bone induction mechanism. The concept of this treatment was to retain the ABC tissue, using its own intrinsic osteogenic potential to promote healing. By triggering intralesional new bone formation, the bone paste represented an effective means to reverse the expanding phase of ABC. The particulated bone allograft was easy to handle and to introduced in an irregular cavity. Moreover, as a complete cyst evacuation was not required, a minimal surgical approach could be used so that the risks and morbidity associated with an extensive approach were reduced. Its use is of particular interest in poorly accessible areas like the pelvis and spine.     

Activation of monocyte/macrophage functions related to acute atheroma complication by ligation of CD40: induction of collagenase, stromelysin, and tissue factor

We describe a patient with rheumatoid arthritis who presented a large femoral-inguinal mass. The mass proved to be a synovial cyst-like structure communicating with rigid cystic lesions at the pubic bone. No obvious communication between the cystic lesions and the hip joint or bursae was seen by hip arthrogram or in surgery. Pathological examination of the cystic lesion at the pubic bone revealed infiltration of multiple rheumatoid nodules with marked fibrinoid necrosis into the bone, with synovium-like tissue on it. However, no synovial tissue was observed in the femoral-inguinal mass. These findings suggest that the femoral-inguinal mass was not a true synovial cyst but can be called a pseudo-synovial cyst arising at the pubic bone region.