BIOPHYSICAL STIMULATION FOR NONUNIONS.

Nonunions account for 5-10% on the total number of fractures. Biophysical stimulation is a non-surgical, conservative, frequently used therapy in nonunions and a greater efficacy has been demonstrated for pulsed electromagnetic fields (PEMF). The mechanisms of action of PEMF at cellular and molecular levels are still under debate and no dose-response study is available. Moreover, the vast majority of in vitro studies were conducted on healthy cells. The primary aim of the research was to investigate the capacity of PEMF with different exposure times to stimulate the osteogenic process in cells from the callus of a nonunion patient. Another important objective was the characterization of nonunion cells in terms of clonogenicity, cluster of differentiation expression and the tri-lineage differentiation capacity. Overall, the results indicated the presence of osteochondroprogenitor cells in the callus of a nonunion, with an impairment in the osteogenic differentiation process. PEMF may enhance cell viability, the formation of osteoid matrix and accelerate the process of osteogenic differentiation. BMP-4 production, TIMP1 and TIMP2 expression were influenced, as well as VEGFA, whose early upregulation may account for a possible improvement in both the osteogenic and vasculogenic processes. In conclusion, even with some discussed limitations, these preliminary data showed the presence of a multipotent progenitor population and suggested some hints of the effect of PEMF on nonunion cells.

A novel DNA profiling application for the monitoring of cross-contamination in autologous chondrocyte implantation.

BACKGROUND: Autologous chondrocyte implantation (ACI) is a cell-based treatment that can be used to regenerate chondral defects. European legislation specifically classifies such produced chondrocytes as "medicinal for advanced cell therapy" that have to be manufactured in pharmaceutical factories according to specific rules, named Good Manufacturing Practices (GMPs). One main requirement of cell manipulation in advanced therapy is to prevent the risk of any contamination. AIM: The aim of this study was to verify if chondrocyte cultures suitable for ACI were free of cross-contamination by means of DNA profiling techniques. MATERIALS AND METHODS: Cell cultures were carried on in a Hospital Cell Factory in compliance with European current Good Manufacturing Practices. DNA profiling, by means of Short Tandem Repeats and miniShort Tandem Repeats analyses, was performed on expanded chondrocytes and their related control blood samples. Mitochondrial DNA was analysed to further confirm the results and to evaluate possible mutations occurred in the samples. RESULTS: Our findings demonstrated the absence of cross-contamination between chondrocyte cultures and, thus, their identity maintenance until the end of the manipulation. CONCLUSIONS: DNA profiling technique can be a suitable test for quality control not only for chondrocyte manipulation, but for cell therapy in general.

Brillouin-Raman microspectroscopy for the morpho-mechanical imaging of human lamellar bone.

Bone has a sophisticated architecture characterized by a hierarchical organization, starting at the sub-micrometre level. Thus, the analysis of the mechanical and structural properties of bone at this scale is essential to understand the relationship between its physiology, physical properties and chemical composition. Here, we unveil the potential of Brillouin-Raman microspectroscopy (BRaMS), an emerging correlative optical approach that can simultaneously assess bone mechanics and chemistry with micrometric resolution. Correlative hyperspectral imaging, performed on a human diaphyseal ring, reveals a complex microarchitecture that is reflected in extremely rich and informative spectra. An innovative method for mechanical properties analysis is proposed, mapping the intermixing of soft and hard tissue areas and revealing the coexistence of regions involved in remodelling processes, nutrient transportation and structural support. The mineralized regions appear elastically inhomogeneous, resembling the pattern of the osteons' lamellae, while Raman and energy-dispersive X-ray images through scanning electron microscopy show an overall uniform distribution of the mineral content, suggesting that other structural factors are responsible for lamellar micromechanical heterogeneity. These results, besides giving an important insight into cortical bone tissue properties, highlight the potential of BRaMS to access the origin of anisotropic mechanical properties, which are almost ubiquitous in other biological tissues.

Decreased periprosthetic bone loss in patients treated with clodronate: a 1-year randomized controlled study.

The efficacy of clodronate to reduce bone loss around uncemented stems after total hip arthroplasty(THA) was evaluated. Ninety-one patients operated with uncemented THA were randomized to receive either intramuscular clodronate at a dose of 100 mg weekly for 12 months or no treatment. Periprosthetic and contralateral bone mineral density (BMD) scans were performed and biochemical markers of bone turnover measured at baseline and at 3, 6, and 12 months. At month 12, with the exception of Gruen zones 4 and 5, patients treated with clodronate showed less bone loss at all zones, reaching statistical significance (P\0.05) in Gruen zones 2 and 6 (difference of 6.6 and 5.9%, respectively). Analysis of data according to gender revealed sex-related differences in bone loss and efficacy of treatment. After 12 months, the difference in bone loss between treated and untreated women in five out of seven Gruen zones ranged from 6.2 to 13.3% (SS at zones 2 and 6), whereas comparison between treated and untreated men showed no BMD differences in all zones(P[0.05). Median percent changes in serum levels of markers of bone metabolism by gender were consistent with BMD changes. A 1-year treatment with intramuscular clodronate determined a significant reduction of bone loss after THA. This was mainly attributed to its greater efficacy in the female population, which is at higher risk for bone loss. This observation suggests the need for the characterization of high-risk subjects as potential candidates for prevention strategies.

Mechano-chemistry of human femoral diaphysis revealed by correlative Brillouin-Raman microspectroscopy.

Brillouin-Raman microspectroscopy is presented as an innovative label-free all-optical investigation approachable to characterize the chemical composition and the mechanical properties of human tissues at micrometric resolution. Brillouin maps unveil mechanical heterogeneities in a human femoral diaphysis, showing a ubiquitous co-existence of hard and soft components, even in the most compact sections. The novel correlative analysis of Brillouin and Raman maps shows that the relative intensity of Brillouin peaks is a good proxy for the fraction of mineralized fibers and that the stiffness (longitudinal elastic modulus) of the hard component is linearly dependent on the hydroxyapatite concentration. For the soft component, a gradient of composition is found, ranging from an abundance of proteins in the more compact, external, bone to abundance of lipids, carotenoids, and heme groups approaching the trabecular, inner, part of the diaphysis. This work unveils the strong potential of correlative mechano-chemical characterization of human tissues at a micrometric resolution for both fundamental and translational research.

Brillouin micro-spectroscopy of subchondral, trabecular bone and articular cartilage of the human femoral head.

Brillouin micro-spectroscopy is applied for investigating the mechanical properties of bone and cartilage tissues of a human femoral head. Distinctive mechanical properties of the cartilage surface, subchondral and trabecular bone are reported, with marked heterogeneities at both micrometric and millimetric length scales. A ubiquitous soft component is reported for the first time, characterized by a longitudinal modulus of about 4.3 GPa, possibly related to the amorphous phase of the bone. This phase is mixed, at micrometric scales, with a harder component, ascribed to mineralized collagen fibrils, characterized by a longitudinal modulus ranging between 16 and 25 GPa.

In vivo study on the healing of bone defects treated with bone marrow stromal cells, platelet-rich plasma, and freeze-dried bone allografts, alone and in combination.

The repair of confined trabecular bone defects in rabbits treated by autologous bone marrow stromal cells (BMSC), platelet-rich plasma (PRP), freeze-dried bone allografts (FDBA) alone and in combination (BMSC + PRP; FDBA + BMSC; FDBA + PRP; FDBA + PRP + BMSC) was compared. A critical size defect was created in the distal part of the femurs of 48 adult rabbits. Histology and histomorphometry were used in the evaluation of healing at 2, 4, and 12 weeks after surgery. The healing rate (%) was calculated by measuring the residual bone defect area. Architecture of the newly formed bone was compared with that of bone at the same distal femur area of healthy rabbits. The defect healing rate was higher in PRP + BMSC, FDBA + PRP, FDBA + BMSC, and FDBA + PRP + BMSC treatments, while lower values were achieved with PRP treatment at all experimental times. The highest bone-healing rate at 2 weeks was achieved with FDBA + PRP + BMSC treatment, which resulted significantly different from PRP (p < 0.05) and BMSC (p < 0.05) treatments. At 4 weeks, the bone-healing rate increased except for PRP treatment. Finally, the bone-healing rate of FDBA + PRP, FDBA + BMSC, and FDBA + PRP + BMSC was significantly higher than that of PRP at 12 weeks (p < 0.05). At 12 weeks, significant differences still existed between PRP, BMSC, and FDBA groups and normal bone (p < 0.05). These results showed that the combination of FDBA, BMSC and PRP permitted an acceleration in bone healing and bone remodeling processes.

Evaluation of bone healing enhancement by lyophilized bone grafts supplemented with platelet gel: a standardized methodology in patients with tibial osteotomy for genu varus.

Orthopedic practice may be adversely affected by an inadequate bone repair that might compromise the success of surgery. In recent years, new approaches have been sought to improve bone healing by accelerating the rate of new bone formation and the maturation of the matrix. There is currently great interest in procedures involving the use of platelet gel (PG) to improve tissue healing, with satisfactory results both in vitro and in maxillofacial surgery. Otherwise, to our knowledge, only a preliminary clinical study was undertaken in the orthopedic field [Kitoh et al., Bone 2004;35:892-898] and the efficacy of PG is still controversial. Our paper focuses on the effect on bone regeneration by adding PG to lyophilized bone chips used for orthopedic applications. The clinical model and the laboratory methodology were standardized. As a clinical model, we employed the first series of patients of a randomized case-control study undergoing high tibial osteotomy (HTO) for genu varus. Ten subjects were enrolled: in 5 patients lyophilized bone chips supplemented with PG were inserted during tibial osteotomy (group A); 5 patients were used as a control (group B) and lyophilized bone chips without gel were applied. Forty-five days after surgery, computed tomography scan guided biopsies of grafted areas were obtained and the bone maturation was evaluated by a standardized methodology: the osteogenic and angiogenic processes were semi-quantitatively characterized by using histomorphometry, and the mineral component of the lyophilized and host bone was analyzed by using X-ray diffraction technique with sample microfocusing and microradiography. Lyophilized bone with PG seems to accelerate the healing process, as shown by new vessel formation and deposition of newly formed bone, with no evidence of inflammatory cell infiltrate, when compared with lyophilized bone without gel. On the contrary, lyophilized bone undergo a resorption process, and a fibrous tissue often fills the spaces between chips. A histiocytic/giant-cell reaction is sometimes present. Otherwise, no differences have been found concerning microstructure. Our findings show the reliability of the methodology used to monitor early bone repair. The completion of the study and the evaluation of the ultimate clinical outcome are necessary in order to verify PG in vivo effects in orthopedic surgery.

Radiological assessment of the PRF/BMSC efficacy in the treatment of aseptic nonunions: A retrospective study on 90 subjects.

BACKGROUND: Nonunion is a major orthopaedic concern because of treatment difficulty, high costs and devastating effects on the patients' life quality. Therefore, there is interest in the use of bone substitutes and cell-based strategies to augment fracture repair. We aimed to verify if Platelet Rich Fibrin (PRF) added with bone marrow stromal cells (BMSC) was able to improve the reparative process in the aseptic nonunion, and to establish whether it was worthwhile with atrophic nonunion. The primary outcome was radiological union. As secondary endpoint, the healing time was assessed, and the radiological consolidation grade at each follow-up. METHODS: We identified 113 subjects with tibia or femur nonunion and retrospectively created two groups. Group A was constituted by 56 subjects who underwent the standard procedure, i.e. Judet decortication with/out internal fixation devices, and opposite cortical homoplastic stick. In 57 patients, the standard procedure was modified by adding PRF and BMSC carried by homologous lyophilised bone chips (group B). The same surgeon performed all the operations. To our knowledge, no data are reported in the literature about such application. Since a "gold standard" for healing quantification does not exist, a new scoring radiological system was applied, at 1.5, 3, 6, 12 and 24 months after treatment. RESULTS: At the final 24-month follow-up, the radiological union percentage was 94,12 in group B and 95,12% in group A. A decreased healing time was demonstrated in the presence of PRF/BMSC in comparison with the standard procedure. When we compared the radiological scores at each follow-up, we found that the PRF/BMSC combination significantly improved the consolidation grade at 1.5-, 3- and 6-month follow-up in femurs and at 1.5-month follow-up in tibiae. Furthermore, an improved consolidation grade was demonstrated in the atrophic subjects treated with adjuvants compared to atrophic patients treated with the standard procedure at 1.5-month follow-up. CONCLUSIONS: This study supports the concept that the use of PRF/BMSC, during the standard procedure, is effective in shortening nonunion healing time. It could allow an early mobilization of patients, minimizing suffering, and could be an effective tool to reduce the health-care costs resulting from this issue. LEVEL OF EVIDENCE: Therapeutic level III.

Bone-resorbing cytokines in serum of patients with aseptic loosening of hip prostheses.

Our aim was to determine if the serum levels of bone-resorbing cytokines (IL-1beta, TNF-alpha, IL-6, GM-CSF) are altered in patients with aseptic loosening of a total hip prosthesis, and if such levels are influenced by the type of implant. We determined cytokine levels in sera from 35 patients before revision for failed total hip arthroplasty and compared them with those in 25 healthy donors. We also assessed the soluble receptor of interleukin-2 (sIL-2r) in serum as an indication of a specific immune reaction against the implant. Our findings showed that the sIL-2r and TNF-alpha serum level did not change. The IL-6 level was not significantly altered, but was higher in patients with TiAIV prostheses than in those with a CrCoMo implant and in patients with cemented prostheses. The IL-1beta level was found to be higher in those with a TiAIV cemented prosthesis than in the control group (p=0.0001) and other groups of patients (p=0.003 v uncemented TiAIV, p=0.01 v cemented CrCoMo, p=0.001 v uncemented CrCoMo). The GM-CSF level significantly increased in patients compared with healthy subjects (p=0.008), and it was higher in those with cemented than with uncemented implants (p=0.01). Only patients with cementless CrCoMo prostheses had levels of GM-CSF similar to those of the control group. The highest GM-CSF concentrations were observed in patients treated with non-steroidal anti-inflammatory drugs (NSAIDs) in the last months before revision (p=0.04). In addition, when massive osteolysis was observed, the level of GM-CSF tended to decrease to that of the control group.

Primary chemotherapy and delayed surgery (neoadjuvant chemotherapy) for telangiectatic osteogenic sarcoma of the extremities.

Twelve patients with telangiectatic osteogenic sarcoma (TOS) of the extremities were treated with neoadjuvant chemotherapy, according to two different protocols. Preoperatively the patients received high-dose methotrexate(HD-MTX)/cisplatinum(CPD) or HD-MTX/CPD/adriamycin(ADM). CPD was delivered intra-arterially, the other drugs intravenously. Limb salvage surgery was performed in eight instances and four patients underwent amputation. Post operative chemotherapy was tailored according to the grade of necrosis determined by preoperative treatment on the primary tumor. In ten cases (83%) the grade of necrosis resulted higher than 95%. The mean length of follow-up was 3.5 years with a range of 18 to 72 months. Ten patients (83%) remained continuously disease-free, while two patients developed lung metastases and died of uncontrolled disease. No local recurrences were observed. These results are better than those observed in 167 contemporary cases of conventional osteosarcoma treated with the same protocols. This study confirms that TOS is not always a lethal tumor as suggested by prior reports. Employing neoadjuvant chemotherapy a high percentage of patients with TOS can be cured and in most of them, limb sparing surgery is possible and safe.

The importance of dose-intensity in neoadjuvant chemotherapy of osteosarcoma: a retrospective analysis of high-dose methotrexate, cisplatinum and adriamycin used preoperatively.

The relationship between dose-intensity and outcome was retrospectively analyzed in 125 patients with osteosarcoma of the extremities treated at our institution with neoadjuvant chemotherapy between 1986 and 1988. Before surgery, chemotherapy was performed with high-dose methotrexate (HDMTX) i.v. followed by cisplatinum (CDP) i.a. and adriamycin (ADM) i.v. Postoperative chemotherapy was tailored according to the necrosis induced by preoperative treatment. Patients who were "good responders" had 31-weeks of chemotherapy with the same drugs utilized preoperatively, while "poor responder" patients received a longer treatment (40 weeks) in which ifosfamide and etoposide (VP-16) were added to HDMTX, CDP and ADM. At a median follow-up of 2 years (1-3 years) 100 patients (80%) remained continuously disease-free and 25 patients relapsed: 24 with lung metastases and 1 with local recurrence. According to the real dose-intensity received, calculated as a percentage of the dose intensity projected by the protocol, the continuously disease-free survival was 87% in the 82 patients who received 80% or more of the scheduled dose-intensity and only 65% for the 43 patients who received less than 80% of the projected dose-intensity. This difference is highly significant (P less than 0.01). These results suggest that in neoadjuvant chemotherapy of osteosarcoma the real dose-intensity delivered is a determinant of treatment outcome and therefore every effort should be made to avoid reductions of doses and delays of cycles of chemotherapy in these patients.

Metastatic patterns in osteosarcoma.

The clinical courses of 193 patients with high-grade, non-metastatic osteosarcoma were reviewed to ascertain the evolution of the natural history of the disease. All patients had the primary lesion in the extremities and were treated at the Rizzoli Orthopaedic Institute between 1976 and 1982 with surgery alone (30 cases) or surgery plus adjuvant chemotherapy (163 cases). All patients were regularly followed at our Institute. One hundred and fourteen patients, of which 27 were treated with surgery alone and 87 treated with adjuvant chemotherapy, developed overt metastatic disease. No differences were found concerning the sites of the first relapse which, for approximately 90% of cases, were lungs in both groups. However, in the group of patients treated with adjuvant chemotherapy the development of overt metastatic disease, as compared to non-adjuvant patients, was delayed with time (13 vs 8 months) and the number of metastatic nodules in the lung at first relapse was reduced. This alteration in metastatic pattern due to adjuvant chemotherapy is important because it allows surgical resection of pulmonary metastases in a larger number of patients (51% vs 29%).

Prognostic value of serum alkaline phosphatase in osteosarcoma.

In 163 patients with osteosarcoma of the extremities treated with adjuvant chemotherapy, serum alkaline phosphatase (SAP) levels were evaluated before treatment and successively closely monitored in an attempt to determine whether serum levels of this enzyme had clinical value in predicting the course of the disease. Of 121 patients with elevated preoperative SAP levels, 78 (64%) recurred. Of 42 patients with normal preoperative SAP levels, only 8 (19%) recurred (P less than 0.00001). Of the 140 patients locally treated with amputation, SAP returned to normal values in 77 patients; 46 of these (59%) relapsed. Of the 21 patients whose SAP remained elevated after amputation, all but 2 relapsed (90%). Among 119 patients with normal postoperative values of SAP, at the time of relapse SAP resulted elevated in 22 of 41 patients (53%). These data confirm that in osteosarcoma, preoperative SAP levels have a definite value in establishing the prognosis and that posttreatment follow-up examination should include SAP determination, since persistent elevated or increasing values herald the appearance of a recurrence.

Neoadjuvant chemotherapy for localized Ewing's sarcoma of the extremities: preliminary results of a protocol which uses surgery (alone or followed by radiotherapy) for local control.

From June 1983 to December 1985, thirty-eight patients with localized Ewing's sarcoma of the extremities were treated with a protocol that consisted of an initial nine week period of polychemotherapy (vincristine, adriamycin and cyclophosphamide) followed by local therapy and additional chemotherapy (vincristine, adriamycin, cyclophosphamide and dactinomycin) for one year. As local treatment all patients were offered surgery; thirty-two accepted and six refused. These six patients were locally treated with radiotherapy alone (50 Gy). In the remaining patients an amputation was performed in one case and a resection in thirty-one. In resected patients when a wide margin was achieved (24 cases) no further local treatment was performed; when it was marginal (5 cases) or intralesional (2 cases) radiotherapy at lower doses (40 Gy) followed. At mean follow-up of thirty-seven months the percentage of continuously disease-free patients was 50% for those treated with radiotherapy, 76% with surgery, and 85% with surgery and radiotherapy. Eight patients developed metastatic disease and two patients had local recurrence and metastases. The local recurrences were seen in one patient locally treated with surgery and in one locally treated with radiotherapy. Nine major local complications were observed: three in patients treated with radiotherapy, five in patients treated with surgery, and one in a patient treated with surgery and radiotherapy. These results indicate that after induction chemotherapy conservative surgery is possible in almost all cases of Ewing's sarcoma of the extremities and that such treatment is better than radiotherapy alone as local therapy.

Primary chemotherapy and delayed surgery for malignant fibrous histiocytoma of bone in the extremity.

Between March 1983 and September 1988, 22 patients with non-metastatic malignant fibrous histiocytoma MFH of bone of the extremities were treated with two regimens of neo-adjuvant chemotherapy successively activated. Preoperatively, the patients received moderate doses of methotrexate and cisplatinum-Regimen 1- or high dose methotrexate, cisplatinum and adriamycin-Regimen 2. Cisplatinum was delivered intraarteriously, the other drugs intravenously. Limb salvage surgery was performed in 20 patients, and 2 patients were amputated. The surgical margins were adequate (radical or wide) in 18 cases and inadequate (marginal) in 4. The histologic response to chemotherapy was good (90% or more tumor necrosis) in 8 patients. In both regimens postoperative chemotherapy was tailored according to the grade of necrosis determined by preoperative treatment on the primary tumor. At an average follow-up of 40 months (15-70), 15 patients (68%) remained continuously disease-free and 7 relapsed with metastases. No local recurrences were observed. Regimen 2 was slightly more effective than Regimen 1 in terms of good histologic response (5/10 vs 1/12) and continuous disease-free survival (8/10 vs 7/127). The results demonstrate that, as in osteosarcoma, in non-metastatic malignant fibrous histiocytoma of bone in the extremities a high percentage of patients can be cured with neoadjuvant chemotherapy and that in most of them limb sparing surgery is possible and safe.

Deep peroneal nerve paresis in a runner caused by ganglion at capitulum peronei. Case report and review of the literature.

Although lateral popliteal sciatic nerve damage is not one of the commonest diseases in the general population, it is quite frequent among athletes. Several physiopathologic mechanisms have been thought to bring about this damage in athletes. Soft tissue ganglions with neurological involvement of the lateral popliteal sciatic nerve or its terminal rami are in differential diagnosis with several lesions of this area, as direct or indirect trauma, subcutaneous rupture of anterior tibialis muscle and long peroneal muscle, disc hernia, intraspinal tumor, anterior tarsal tunnel syndrome, cysts, neurofibroma, baker's cyst, vascular claudication, stenosing or inflammatory pathology of 2(nd) motoneuron, antimicrobial agents for urinary tract infection (nitrofurnantoin). The authors report the case of a 34-year-old amateur athlete with a recent paralysis of the hallux extensor, paresis of the toe extensor and hyposthenia of the tibialis anterior. The patient had been suffering from episodes of lumbalgia for a long time. He was sent to us because neurological damage due to disc herniation was suspected. Electromyography, sonography, and CT showed peripheral compression of the deep peroneal nerve caused by a mucous cyst at the capitulum peronei, a ''rare'' condition. The patient underwent surgery to excise the cyst, which led to the rapid resolution of the nerve deficit shown by clinical and electromyographical tests. A meticulous anamnesis and accurate objective examination, followed by specific tests (radiographs, sonography, and possibly CT scan) generally enable a correct diagnosis to be made. If diagnosis and therapy are carried out correctly, and without delay, symptoms quickly resolve and the nerve deficit progressively regresses.

Recurrent posterior instability of the shoulder: surgical treatment.

A total of 11 cases of posterior instability of the shoulder surgically treated by simple capsuloplasty or associated with reinforcement of the posterior wall by bone graft or muscle transposition were reviewed. Accurate selection and preoperative evaluation of the patient when choosing surgery is very important. For surgery to succeed prolonged postoperative immobilization and an intense rehabilitative program to be initiated prior to surgery are necessary. Generalized ligamentous hyperlaxity constitutes a negative factor in prognosis, so that it is important to associate capsuloplasty with posterior bone block, in an attempt to avoid the risk of recurrence as further surgery would have an unfavorable outcome.

A study of the mechanical and biological behavior of bioceramic hip arthroplasty followed-up after more than 10 years.

The authors report the results obtained in three experiments conducted on hip arthroplasty with ceramic-ceramic coupling and the evaluation of clinical follow-ups carried out on cemented bioceramic arthroplasty more than 10 years after surgery. A first test consisted in the "in vivo" study of alumina powder injected in the joints of four pigs with the purpose of verifying the biocompatibility of the compound. A second test involved the experimental evaluation of "in vitro" wear of the alumina as compared to other types of coupling, and confirmed the very low tendency of wear in alumina. A third spectroscopic study conducted using a Raman laser demonstrated the absolute biostability of the surface of bioceramic material. A retrospective clinical study was conducted in order to verify laboratory data in 83 cemented bioceramic arthroplasties followed-up more than 10 years after surgery and of which 92% obtained good clinical results.

The biological problems of total hip arthroplasty.

Biological phenomena are the principal agents in triggering hip prosthesis aseptic loosening. The authors report the results of "in vivo" and "in vitro" and Raman-laser experimental tests, which confirm the validity of the ceramic-ceramic combination in relation to the amount of wear and biocompatibility of friction materials.