Effects of hydroxyapatite tricalcium phosphate coating and intracancellous placement on bone ingrowth in titanium fibermetal implants

The purpose of this study was to compare the host—bone response to hydroxyapatite/tricalcium phosphate (HA/TCP)-coated and noncoated titanium fibermetal implants placed in a load-sharing cancellous bone environment of the distal femurs of rabbits. The influence of implantation site was also investigated by comparing these intracancellous implants with intramedullary implants evaluated in a previous study. Three parameters were measured: percentage implant perimeter surface length in contact with new bone, percentage internal fibermetal surface length in contact with ingrown bone, and percentage of available pore space filled with bone. The HA/TCP coating significantly accelerated and increased bone ongrowth, new bone formation on the perimeter and internal surface of the implants. This effect was evident as early as 2 weeks after implantation. In contrast, there was no difference between HA/TCP-coated and noncoated implants in the bone ingrowth parameter, percentage of available pore space filled with bone, or pull-out strength. Scanning electron microscopy in the backscatter mode demonstrated that new bone formed directly onto the HA/TCP-coated fibers and did not usually form directly on noncoated fibers. Analysis of fluorochrome labeling revealed that bone formation in weeks 1 through 4 was primarily woven and there-after lamellar. Compared with intramedullary placement, intracancellous placement significantly accelerated the apposition of bone to the perimeter and internal surface of HA/TCP-coated implants and both accelerated and increased bone ingrowth as a percentage of available pore volume. These data show that the host response to titanium fibermetal implants is influenced both by HA/TCP coating and by the implantation site.     

Bioresorption of ceramic strontium-85-labeled calcium phosphate implants in dog femora. A pilot study to quantitate bioresorption of ceramic implants of hydroxyapatite and tricalcium orthophosphate in vivo

Ceramic hydroxyapatite and tricalcium orthophosphate were radioactively labeled with their strontium-85 analogs. Porous blocks of these materials (dimensions 2.5 X 1.25 X 0.5 cm) were implanted into surgically created defects in dog femora. The fate of the implants was studied by roentgenography, radioactivity measurements, histology, and microradiography. The radioactivity over the implant site was followed for 22 weeks. Implants were retrieved after 20-25 and 50-55 weeks. Hydroxyapatite implants were not affected by biodegradation processes, while tricalcium orthophosphate implants were subject to extensive bioresorption (25%-30% in 22 weeks). Resorption debris from tricalcium orthophosphate implants was found in mononuclear phagocytes and multinuclear osteoclastlike cells. The supposition is that tricalcium orthophosphate is transformed into hydroxyapatite in a physiologic environment. Labeling of ceramic calcium phosphate implants with strontium-85 analogs offers an adequate technique to quantitate bioresorption in vivo.     

Computer-generated titanium cranioplasty: report of a new technique for repairing skull defects.

A review of 40 cases of titanium cranioplasty fabricated from impressions taken of the defect through the patient's scalp in the conventional way showed that 23% were ill-fitting and 41% of frontal plates had a poor aesthetic result. Attributable factors were difficulty in defining the defect border accurately and limited information of the surrounding tissue architecture which led to strains produced during insertion. Inadequate communication between surgeon and prosthetist compounded these difficulties. A prospective study of six cases fabricated from CT computer-generated models of challenging cranial defects appears to show significant improvements in plate design, resulting in better plate adaptation, stability and aesthetic contour. Plate insertion was rapid (mean time 27 min) thereby minimizing operating time. This paper also discusses the advantages of the enhanced information derived from CT and describes the potential for pre-craniotomy template and matching cranioplasty, thereby permitting a one-stage procedure.     

Cranioplasty using autologous calvarial bone graft in combination with titanium mesh plates for patients with a history of bone infections after initial cranioplasty

We present a modified method for reconstruction of calvarial bone defects for patients with a history of infectious complications. Three patients who had experienced implanted bone infections underwent reconstruction of calvarial bone defect. For reconstruction of the calvarial bone defects, autologous split calvarial bone grafts were used to cover the calvarial bone defect. The full or half layered fronto-parietal bone used as implants were fixed with titanium mini-plates for primary bone defect site, while the new bone defect site caused by getting autologous bone graft were covered with titanium mesh plates assisted by residual half layered calvarias. The average follow-up span of patients was 64 months. Evaluated clinical and radiologic results are stable, showing no measurable side effects. Split calvarial bone graft in combination with titanium mesh plates is recommended in patients with a history of infection or high risk of infection.     

A technique for intraoperative creation of patient-specific titanium mesh implants

Prefabricated, patient-specific alloplastic implants for cranioplasty reduce surgical complexity, decrease operative times, minimize exposure and risk of contamination, and have resulted in improved aesthetic results. However, in creating a prefabricated custom implant using a patient’s computed tomography data, a stable, unalterable defect must be clearly defined before surgery. In the event that an intraoperative modification of an exiting skull defect is required, or in cases of tumour resection in which the size of the skull defect is unknown preoperatively, these prefabricated implants cannot be used. The ideal method for alloplastic cranioplasty would enable cost-effective creation of a patient-specific implant with the capacity for intraoperative modification.The present article describes a novel technique of cranioplasty that uses a patient’s computed tomography data to create a custom forming tool (ie, mold), enabling intraoperative creation of a patient-specific titanium mesh implant. The utility of these implants in creating a custom reconstructive solution in cases in which the size of the skull defect is unknown preoperatively will be demonstrated using two case presentations.     

灭活自体颅骨回植钛铆钉固定的临床应用

目的 总结灭活自体颅骨回植以钛铆钉固定进行颅骨修补术的临床应用经验。方法 2000年3月至2003年12月对21例急性颅脑损伤等去骨瓣减压或颅骨本身受肿瘤侵蚀的患者，行自体颅骨普通冰箱冰冻保存后煮沸消毒，早期回植或受肿瘤侵蚀的骨瓣灭活后一期回植，以钛铆钉固定，随访观察修复效果。结果 所有病例伤口均一期愈合，无并发症发生，随访6个月至2年半，X射线片及CT显示回植骨瓣边缘吸收未超出钛铆钉固定范围，头颅外观及牢度良好，肿瘤无复发。结论 灭活自体颅骨回植进行颅骨修补术，方法简单、实用，利用钛铆钉固定可有效防止因回植骨瓣边缘吸收而导致的牢度下降。     

Silastic implants for correction of pectus excavatum. A new technique

A new technique consisting of the subcutaneous insertion of molded Silastic implants in patients with pectus excavatum deformities is presented. This method of correction should be considered for patients who are devoid of cardiac and respiratory symptoms and for those in whom the only operative indication is cosmetic. The surgical technique is simple, the complication rate is low, and patient tolerance is good. The cosmetic appearance at one year appears excellent.     

A technique for pediatric chest wall reconstruction using custom-designed titanium implants: description of technique and report of two cases

Purpose

We present a surgical technique for chest wall reconstruction using custom-designed titanium implants developed for two female patients to provide both chest wall symmetry and adequate stability for staged breast reconstruction.

Methods

A retrospective review was performed for two adolescent female patients with large chest wall defects who underwent the described technique. The etiology of the chest wall deficiency was secondary to Poland’s syndrome in one patient, and secondary to surgical resection of osteosarcoma in the other patient. For each patient, a fine-cut computed tomography scan was obtained to assist with implant design. After fabrication of the prosthesis, reconstruction was performed though a curvilinear thoracotomy approach with attachment of the implant to the adjacent ribs and sternum. Wound closure was obtained with use of synthetic graft material, local soft tissue procedures, and flap procedures as necessary.

Results

The two patients were followed post-operatively for 35 and 38 months, respectively. No intra-operative or post-operative complications were identified. Mild scoliosis that had developed in the patient following chest wall resection for osteosarcoma did not demonstrate any further progression following reconstruction.

Conclusions

We conclude that this technique was successful at providing a stable chest wall reconstruction with satisfactory cosmetic results in our patients.

     

Osseointegration of polyethylene implants coated with titanium and biomimetically or electrochemically deposited hydroxyapatite in a rabbit model

Purpose

The aim of this study was to evaluate the osseointegration of a new coating directly deposited on PE at room temperature.

Methods

Thirty-six (36) male New Zealand rabbits were randomly assigned to receive one out of three types of implants: two tested implants, i.e. PE implant coated with TiPVD and biomimetic HA (biomimetic), PE implant coated with TiPVD and electrolytic HA (electrolytic), and positive control made of massive microrough titanium coated with plasma sprayed HA (TiHAPS). Osseointegration was evaluated by histomorphometry (bone tissue in contact [BIC]), mineralized bone area [MBA]) and mechanical testing (push-out test, interfacial shear strength [ISS]) at six and 12 weeks in the distal femurs.

Results

For BIC there were no differences between the groups at six (p = 0.98) and 12 weeks (p = 0.13). For MBA, no statistically significant difference was measured between groups at six (p = 0.52) and 12 weeks (p = 0.57). At six weeks, interfacial shear strength (ISS) was significantly higher (p = 0.01) for TiHAPs implants compared to biomimetic and electrolytic implants. This difference was not significant at 12 weeks (p = 0.92).

Conclusion

The osseointegration of biomimetic and electrolytic implants was equivalent to a positive control at 12 weeks.     

Postmortem comparative analysis of titanium and hydroxyapatite porous-coated femoral implants retrieved from the same patient: A case study

The results of bilateral postmortem analysis of titanium and plasma-sprayed hydroxyapatite (HA) porous-coated femoral components of the same Anatomic Porous Replacement design retrieved from a 35-year-old female donor are reported. Analysis was conducted using backscattered electron imaging, histology, and radiographic techniques. The appositional bone index, percent bone ingrowth, and mineral content were measured for both implants. The results showed a 177% higher appositional bone index (P=.014) for the HA porous-coated Anatomic Porous Replacement component compared to the titanium Anatomic Porous Replacement component. Backscattered electron analysis showed 50% more bone in the HA porous-coated implant (P=.028). The mineral content analysis demonstrated that the bone ingrown into the HA porous-coated device was 23% less mineralized (P=.016). The data from this case study suggested that plasma-sprayed HA porous-coated implants may assist in increasing the amount of bone ingrowth and skeletal attachment in total hip arthroplasties.     

Prospective study on cranioplasty with individual carbon fiber reinforced polymer (CFRP) implants produced by means of stereolithography

BACKGROUND: The aim of this study was to evaluate the value of carbon fiber reinforced polymer (CFRP) cranial implants produced by means of 3-dimensional (3D) stereolithography (SL) and template modeling for reconstructions of complex or extensive cranial defects. PATIENTS: A series of 41 cranioplasties with individual CFRP implants was performed in 37 patients between April 1996 and November 2002. Only patients with complex and/or large cranial defects were included, most of them having extended scarring or dural calcification and poor quality of the overlying soft-tissue cover after infection or multiple preceding operations. Involvement of frontal sinus, a known risk factor for complications after cranioplasty, was the case in 21 patients (51.2%). METHODS: A computer-based 3D model of the skull with the bony defect was generated by means of stereolithography after acquisition, evaluation and transfer of the patient's helical computed tomography (CT) data. A wax template of the defect that was used to design the individual prosthesis-shape was invested in dental stone. Then, the cranial implant was fabricated out of CFRP by loosen mold. RESULTS: Reconstruction of defects measuring up to 17 x 9 cm was performed. The intra-operative fit of the implants was excellent in 36 (87.8%), good in 1 (2.4%), and fair in 4 (9.8%) of the cases. Problems of implant fit occurred because of extended scarring and poor quality of soft-tissue cover. Adverse reactions were observed in 5 patients (1 subdural, 1 subcutaneous hematoma, 2 infections, 1 allergic reaction). Excellent contours and a solid stable reconstruction have been maintained in 30 out of 35 remaining plates (mean follow-up 3.6 years). No adverse effects concerning postoperative imaging, the accuracy of electroencephalograms and radiation therapy have been observed. CONCLUSIONS: The authors believe that this relatively new technique represents an advance in the management of complex and large cranial defects, but seems less suitable for simple defects because of cost-intensive techniques. Because of the high mechanical strength, biocompatibility, innovative design, and especially radiolucency, CFRP implants should, however, be considered in smaller defects if further imaging investigations or irradiation therapies are necessary.     

Alendronate-eluting polyglucose-lignol composite (POGLICO): A new biomaterial for fracture fixating implants

Background and purpose —

Due to the known drawbacks of metal implants, new biomaterials for internal fracture fixation are attracting increasing interest, among them poly(lactic-co-glucolic) acids (PLGAs) and the recently developed silk-tenoin derived materials (STDMs). In accordance with the new philosophy of bio-derived biomaterials (BIODERIBIOs), I describe a novel innovative technology for use in fracture fixation.

Patients and methods —

Screws (2 mm dia.) were manufactured from cylindrical bars of polyglucose-lignol composite (POGLICO) in the form of birch toothpicks from the hospital canteen, dip-coated with alendronate (1 mg/mL, n = 6) or saline (n = 6), and inserted in the proximal tibias of rats for 4 weeks. Fixation was evaluated by mechanical pullout testing. POGLICO nails were inserted in the contralateral tibia for microCT and histology.

Results —

All POGLICO implants remained fixed in the bone (p < 0.001) with a mean pullout force of 37 (SD 5.5) N. MicroCT showed that the control nails were surrounded by a thin layer of new bone, while all bisphosphonate-treated implants were surrounded by a thick layer of cancellous bone. Bisphosphonates more than doubled the bone density around the nails (p = 0.004).

Interpretation —

POGLICO is biocompatible, remains in situ, and appears to provide a higher resistance to pullout forces than bulk silk protein. The material is light, strong, and bio-derived. BIODERIBIO-POGLICO can be sterilized by autoclaving, and has a porous surface that can serve for slow release of drugs applied by simple dip-coating, as demonstrated by the effect of the alendronate treatment. As the raw material for the screws is readily available from the toothpick industry, I believe that the possibilities for commercial development of the material for fracture fixation are promising.In order to eliminate the problems associated with metal implants, such as temperature sensitivity (Perrone et al. 2014), the development of non-metal, resorbable implant materials has gained increasing interest. Such materials include polylactic-co-glucolic acids, which are, however, associated with problems of local inflammation due to degradation products (Bostman and Pihlajamaki 2000). For this reason, a new biomaterial—bulk silk-tenoin—has recently been tested for biocompatibility and reported in a high-impact journal (Perrone et al. 2014). This material is claimed to be superior to poly(lactic-co-glucolic) acids in many ways, including biocompatibility, its ability to undergo machining and autoclaving, and its usefulness for elution of drugs (Perrone et al. 2014). In view of these recent advances in the research on bio-derived biomaterials (BIODERIBIO), I have tested another material, namely birch, in much the same way as the silk-derived implants were tested. I found that birch may be equally useful and has advantages over silk from its well-documented use in other fields of construction, its easy availability, and the manufacturing know-how gained through the toothpick industry.Local bisphosphonate treatment has been shown to improve implant fixation in clinical randomized trials of knee prostheses, external fixation pins, and dental implants (Hilding and Aspenberg 2007, Abtahi 2012, Toksvig-Larsen and Aspenberg 2013). I therefore determined whether birch could also act as a carrier of a bisphosphonate.     

A prospective study of computer-aided design and manufacture of titanium plate for cranioplasty and its clinical outcome

The use of computerized three dimensional imaging and automated milling of models to produce accurate titanium plates for the reconstruction of craniofacial defects is described. A total of 148 patients have had extensive calvarial defects repaired using this (computer aided design and manufacture) technique developed in our unit. Of these, 141 were repaired secondarily (delayed cranioplasty), whilst seven were repaired immediately following craniectomy (single stage cranioplasty). All cases were assessed for accuracy of fit, restoration of natural skull contour and aesthetics. Seventy-two patients were reviewed after 1 year to determine the effect on adverse preoperative symptoms. Of the plates 97% had an excellent or good intraoperative fit. The modal insertion time was only 15 minutes. Postoperatively 98% resulted in the restoration of natural skull shape and symmetry. After 1 year, 82% of patients had complete resolution or diminution in severity of the adverse symptoms. A staphylococcus infection necessitated the temporary removal of one plate.     

Comparison of the early healing course of porous titanium with hydroxyapatite-coated porous titanium hip implants: clinical considerations for the use of hydroxyapatite coating in total hip replacement

The role of hydroxyapatite (HA) coating in the fixation of human total joint prostheses remains to be established. Results of animal studies have been favorable, showing very rapid bone formation with a corresponding increase in bone-implant bond strength. In addition, the quantity of bone may be increased. This study compared identical porous titanium primary total hip implants with and without HA in similar patient populations. All of these patients were healthy and reliable, and had optimal bone geometry and bone quality for cementless fixation. The purpose of the study was to contrast the sequence of events, in the first year after surgery, between the two implant groups to identify the contribution of HA to early patient function and early radiographic appearance of the prosthesis. No significant clinical difference could be demonstrated between the two groups at 1 year from surgery. However, the HA group progressed more rapidly when comparing clinical scores at 6 months (P = .0058), and appeared to demonstrate more rapid bone remodeling at 6 months on the femoral side, although this observation did not quite make statistical significance (P = .0618). There was no difference between the acetabular components during the course of this study.     

Histological findings in guided bone regeneration (GBR) around titanium dental implants with autogenous bone chips using a new resorbable membrane

The aim of this study was to test the value of the new polydioxanone-membrane (PDS, Ethicon, Norderstedt, Germany) in combination with autogenous bone as a spacer for guided bone regeneration of denuded implant surfaces compared to simple augmentation. Forty implants were selected for 20 test cases (with membrane) and 20 control cases (without membrane) and were distributed randomly in 19 patients who were treated according to a standard protocol and examined. The defects were filled with autogenous bone chips, harvested interforaminally or locally, and were covered by the PDS membrane within the test group (control group: periosteum). The membranes were fixed with Memfix screws and cover screws. Seven membranes became exposed and were removed before reentry. Within the control group, three augments were sequestered. After 6 months, reentry was performed, the healing results were observed clinically, and biopsies were taken. The test group, including the seven cases with early removal of the membrane, showed that bone had filled in the defects in 95% of test cases, compared with 60% for the control group. The results of this study show that single augmentation of defects exceeding 9 mm2 is not sufficient. The membrane used in this investigation may be helpful for guided bone regeneration (GBR) at denuded screw thread sites in implant dentistry.     

Platelet-rich fibrin (PRF) in implant dentistry in combination with new bone regenerative technique in elderly patients

IntroductionSome studies have demonstrated that platelet rich fibrin (PRF) is a healing biomaterial with a great potential for bone and soft tissue regeneration, without any inflammatory reactions and may be used alone or in combination with bone grafts, promoting hemostasis, bone growth, and maturation. PRF appears as a natural and satisfactory aid in bone regenerative surgery in elderly patients with favorable results and low risks.AimThis study wants to demonstrate how PRF in association with a new split crest augmentation technique can be a great aid in implant rehabilitation, especially in the elderly patients, when bone regeneration is required.Materials and methodsTen patients were treated in this study, five following the flapless split crest new procedure and other five patients following traditional procedure without split crest as control. Five patients with an average age between 50 and 60 years were selected to be operated with a split crest flapless modified technique in order to optimize the regenerative conditions with a bone augmentation and implant insertion in one single stage procedure. For all the patients autologous PRF has been used to fill the split crest gap or simply as regenerative material. Orthopantomography, intraoral radiography and CT DentaScan/CT Cone beam were performed for every patient before the treatment and at follow-up time exeption made for CT.ResultsAll cases were successful, there were no problems at surgery time, at post-operative and at osteointegration periods. All implants achieved osteointegration. These results were obtained by accurately managing immediate and late post operative period in all of the operated cases. Mean difference for height bone loss between the two groups of patients was 2.4 mm at T1 and 2.2 mm at T3.DiscussionThe rationale of this split crest flapless modified technique is to obtain a proper buccal cortex expansion preserving its vascular supply avoiding periosteal elevation for better cortical bone nourishing. Moreover, advantages are reported related to the use of PRF. The effectiveness of PRF is shown in promoting the healing of surgical wounds, it has, in fact, platelet growth factors that can improve the vascularisation of the surgical site, promoting neoangiogenesis. Furthermore, by simply changing the settings of the centrifuge, it is possible to obtain a normal gelling if it has to be used as regenerative and stimulating material, or more consistent substance to be used as a filler in the split crest gap.ConclusionsThe main advantages in using the platelet-rich fibrin are healing and bone regenerative properties in combination with its complete resorption after surgery, thus avoiding a second surgery time, important factor in the elderly patients. Currently, it is a minimally invasive technique with low risks and satisfactory clinical results such preventing complications or implant failure particularly in elderly patients for age related conditions.