Introduction

The number of total hip arthroplasties in young patients is continuosly increasing. Nowdays, the study of the materials wear, with the goal of improving the survivorship of implants, represents a fundamental subject in this kind of surgery. The role of ceramic materials in the valutation of types of wear is particularly known.

Background

Tapered cementless femoral components have been used in total hip arthroplasty (THA) constructs for more than 20 years. The Synergy femoral component was introduced in 1996 as a second generation titanium proximally porous-coated tapered stem with dual offsets to better restore femoral offset at THA (Figure 1). The purpose of this study was to evaluate the outcome of the authors' experience using the Synergy stem at minimum 15 years of follow-up.

Pure tantalum has been proposed in orthopaedic surgery. Its chemical and physical properties have been widely studied in the past. From pure tantalum is obtained a spongy structure (Trabecular Metal Technology: TMT) that shows a full thickness porosity which is 2–3 times higher compared to other surfaces available for bone ingrowth with a three-dimensional porous arrangement in rough trabeculae. Pores (average diameter of 650 mm) are fully interconnected and represent 75–80% of the whole volume. TMT acetabular components have an elliptical shape and have an irregular external surface which both allow an optimal mechanical fit.

We retrospectively reviewed 212 cases of monoblock porous tantalum acetabular cup (Hedrocel, Stratec) implanted between 1999 and 2003 in a single centre with a minimum follow-up of 9–10 years; There were 98 men and 114 women, with an average age of 65 years. They all underwent primary or revision total hip arthroplasty or to acetabular component revision alone. In all patients a monoblock porous tantalum acetabular component with polyethylene directly compression molded into cup, with or without peripheral holes for screws, was implanted. In all primary procedures the same femoral stem (Synergy, Smith and Nephew) was implanted.

All patients were evaluated with a clinical examination (Harris Hip Score: HHS) and with standard radiographs of the pelvis preoperatively and 1, 3, 6 months and yearly postoperatively. The stability of the acetabular cup was determined by modified Engh's criteria.

The HHS score improved from 42 preoperatively to 94 after one year; at 13 years follow-up it was 95. The subjective outcome was widely satisfying, with the majority of patients experimenting good functional recovery and return to daily activities. Osteointegration of the acetabular component was present in all X-rays controls at one year after surgery. All post-operative evidence of residual bone loss (geodes, bone defects in revisions and in displasia) were no more radiographically evident after 1 year postoperatively as the host bone quickly filled these gaps. We did not observe osteolysis nor progressive radiolucent lines at the latest follow-up. None of the cups was revised, except 3 cases, revised for infection.

Both clinical and radiographic results are the same or even superior to those of coated implants. Our experience confirms that trabecular metal tantalum cups can avoid the formation of bone-implant interface membrane and consequently can avoid implant loosening. The most important advantages of TMT monoblock cups are: no potential for polyethylene backside wear, prevention of loosening and osteolysis, increased early fixation via friction, improved late biological stability, maximum bone-implant contact. High biocompatibility of porous tantalum and its elastic modulus very close to bone influence positively earlier and wider osteointegration of the implant. Larger series are needed to confirm the positive our preliminary results.

Background: Poor results were observed at medium term follow-up (FU) after first and second generation cementless stems implantation in total hip arthroplasty (THA). Revision rate up to 24% is reported with anatomic stems; stress-shielding rate up to 50%, thigh pain rate up to 21%, loosening rate up to 20% and osteolysis rate up to 29% were reported with cylindrical stems. A third generation tapered stem, the Synergy stem, was introduced in 1996 to rise such weakness points.

Material and methods: A retrospective, cohort study was carried out in two academic centers (London, Toronto, Canada & Rome, Italy) on 232 primary THA in 215 patients with a 10 to 12 yrs FU. Mean age at surgery was 60 yrs (18–82), 95 patients were males and 120 females. Thirty-six patients were lost at FU (13 died before the 10 yrs mark, 22 changed residency, 1 not willing to be seen) with no problems related to the replaced hip. Remained at FU 196 THA. Patients selection: Dorr type A and B femurs suitable for receive a Synergy stem. Its characteristics are the following: Ti-6Al-4V, straight, tapered, 3D wedge cross-section, proximal antirotational fins, low-profile neck, neck angle 131°, metaphyseal part porous or HA coated, diaphyseal part grit blasted, polished tip, surgeon-friendly ancillary instruments. Clinical results of the 196 THA with more than 10 yrs of FU were assessed preoperatively and postoperatively at 5 and 10 or 11 or 12 yrs by means of standard evaluation tools: SF12, WOMAC and Harris Hip Score. Thigh pain frequency and intensity were also scored. Radiographic analysis was focused on stem alignment, bone ingrowth, radiolucent lines presence, width and progression, stress-shielding, heterotophic ossification (HTO). Student paired test and Kaplan-Meier survival analysis were used for statistical analysis.

Results: All clinical evaluation tools showed both at 5 years FU and at latest FU (10–12 years) a statistically significant (p=0,001) improvement compared to the preoperative scores. We observed a not constant thigh pain in 7 patients (5,5%). Nineteen patients (10%) underwent evision due to polyethylene wear (6 cases), late periprosthetic fracture (5 cases), subsidence (2 cases), instability (3 cases), infection (3 cases). Cumulative survival rate was 97% at 2 and 5 years, 90% at 10 years. Stem related revisions were the 2 cases of subsidence, both related to occult intraoperative calcar crack and early revised (within 1 year); cumulative stem-related survival rate at 10 years was 99%. Alignment was varus in 9 cases and valgus in 3. Bone in-growth was observed in 194 patients (98%). Radiolucent lines were uncommon, non progressive, less than 2 mm, in Gruen zones 2 and 6. Stress-shielding was present as cortical reaction in 5 femurs in Gruen zones 3 and 5. Thirty-four cases of HTO (grade I and II in 27 case and grade III in 7 cases) were observed.

Conclusions: The Synergy stem demonstrates excellent clinical and radiographic results at 10–12 yerars FU in 196 patients. Survivorship (with stem revision as end point) is 99% at 10 years. Thigh pain is uncommon and the level of activity and autonomy is excellent. Radiographically bone ingrowth is evident in all stems and radiolucent lines are “benign” with no aseptic loosening. Attention must be paid at the moment of stem press fit insertion to avoid occult proximal femoral fractures that may require revision surgery.

The experimental determination of residual stress fields on the surface of retrieved femoral heads represents a fundamental step in understanding their wear degradation behavior and the tribological mechanisms, which are operative on the femoral joint during its working life time. In this work, the surface of retrieved alumina and zirconia (Al2O3 and ZrO2) femoral heads were investigated by piezo-spectroscopic tecniques based both on photoluminescence and Raman effects. The high spatial resolution of the laser, impinging on the investigated surface (typically about 1 micron of lateral resolution), enabled us estimating patterns and magnitude of residual stress in extremely narrow zones, comparable with the grain size of the material.

Four retrieved ceramic femoral heads were analyzed. Two balls were made of alumina with a typical grain size of from 4 to 10 microns. Both alumina balls were retrieved after only few years from implantation, due to septic and aspetic loosening. The remaining two femoral heads were made of zirconia with a typical grain size of 1 micron. These latter balls were retrieved after 2 and 13 years, respectively (both for loosening problems). With a systematic collection of a large number of data on a microscopic level it was possible to assess the retrieved femoral heads in to to, thus extending the microscopic analysis to the entire joint.

In allumina balls retrieved after short time implantation, a macroscopic stress field was found, which arose from manufacturing, loading history, and the displacements acting on the femoral head during its lifetime. This stress field was completely overcome by a microscopic residual stress field due to local contacts (e.g., local shocks owing to microseparation, impinging and wear contacts). On the other hand, in zirconia femural heads, the major amount of surface deterioration after long-term exposure arose from tetragonal-to-monoclinic transformation in biological environment. These data allowed us to draw interesting considerations about the role of the material microstructure and the peculiar kinematic mechanisms involved with the use of femoral heads made of different materials.

Spectroscopic techniques, which are complementary to in vitro testing procedures and stress analyses based on finite-element methods, can be very useful for improving the design of the femoral head and for optimizing the microstructural characteristics of the ceramic materials employed. Based on this and previous fluorescence and Raman spectroscopic studies, we also propose that a systematic screening of the ceramic implants before implantation can strongly reduce the probability of failure of the implant.

During the past fifty years metal hip implants have been used in orthopaedics. While these implants are considered biologically inert, several studies indicated that prosthetic implants could release metal ions following wear. The aim of this study was to evaluate serum and urine concentrations of metal ions in patients treated with hybrid surface replacement of the hip.

Co, Cr, Mn, Mo, and Ni in the serum and urine of 14 patients and 19 controls were quantified by Sector Field Inductively Coupled Plasma Mass Spectrometry (SF-ICP-MS). A Spectrometer ELEMENT (Finnigan MAT, Bremen, Germany) was used at the following resolution: 98Mo, 100Mo, (m/D;m = 300); 52Cr, 53Cr, 55Mn, 59Co, 60Ni, (m/D;m = 3000). The internal standard method (In) was applied to correct the random fluctuations of the signal. Indium was added to the sample solutions so as to reach a final concentration of 1 ng mL-1. Limits of Detection were calculated on the basis of the 3=555; criterion for 10 replicate measurements of solutions containing dilute pooled blood serum and dilute pooled urine, and recovery was obtained by quantifying the analytes of interest in spiked serum and urine. Recoveries of the elements ranged between 94.6% (serum Cr) and 118% (urine Ni).

Data support the assumption that the concentrations of Co and Cr (the major components of the alloy) are substantially higher in serum and urine of patients than in those of controls while for the other elements no specific trend could be observed.

Actually there isn’t any explanation on the possible biological consequences related to the increase of the metal ions levels although many hypothesis have been made. Further studies are thus mandatory to clarify this pattern.

Alumina ceramic has been used in total hip arthoplasty since the 70’s and, in the last 30 years, a considerable evolution has occurred in designing the microstructural features of this material, taking advantage of improved processing techniques, as the hot isostatic pressing. As a result, a high degree of densification (> 99.5) has been achieved in materials with a high degree of purity and, especially, with a fine grain size ( 2 microns). The surface stress field acting on a femoral head inoperation is not only due to working conditions, but also to unexpected factors, as local impacts on the surface as a result of partial dislocations, formation of debris, etc. These additional factors greatly contribute to activate degradation mechanisms which, unfortunately, may lead to failure of the implant.

In this study, five alumina femoral heads were investigated, which were retrieved from patients after different periods of time. Among those investigated femoral heads, two belonged to a first-generation type of alumina material with a relatively coarse grainsize (average value 8 microns) and were retrieved due to surface degradation after long periods of implantation (19 and 17 years, respectively); the remaining three implants analyzed were instead recently manufactured implants with a fine grain size; they were retrieved after relatively short periods because of different causes as, for example, cup or stem loosening.

Surface stress analysis using the luminescence of Cr3+impurity in alumina was performed on the retrieved femoral heads and a statistical comparison was attempted among implants with different microstructural characteristics. The investigation led to estimate average residual stress and statistical stress distributions as a function of the location on the femoral head.

The analysis was performed both on the very surface and in the sub-surface of the head, using the confocal and the through-focus configurations of the optical spectrometer, respectively. Different statistical distributions of residual stress were observed in alumina femoral heads with different grain sizes and models were created to understand their dependence on processing and surface loading.

In primary malignant bone tumours, the “en – block” excision with the sacrifice of soft tissues causes a functional deficit of the interested limb. There are many possibilities for reconstruction after a wide resection of the proximal humerus. The Authors report their experience using megaprostheses, focusing to soft tissue reconstruction, in order to obtain a good and fast functional recovery of the involved limb. 13 megaprostheses of the proximal humerus were employed. All patients were affected of primary malignant bone tumors with different histology. The tumor was staged according to Enneking’s system. 8 cases were classified as IIB and the remaining as IIA. All the tumors were treated with an intrarticular resection. Soft tissues reconstruction was performed, in 8 cases, using a mesh (Trevira tube), dressed all along the prosthesis, with a high resistance to traction. Radio and/or chemotherapy were employed referring to the histology.

At a medium follow – up of two years, for the surviving patients, we have obtained excellent functional results in 1 case, good in seven cases, fair in three cases and poor in two cases. The size of the resection is a main factor in order to obtain a good functional recovery of the joint motion. A wide excision (below deltoid insertion) with the sacrifice of large muscular masses and of the osteoarticular structures can represent a functional amputation causing the loss of muscles that are important to have an acceptable joint movement.

In our experience we retain that the use of modular prostheses in reconstructive orthopaedic surgery is advantageous because of its versatility and of its quick implantation, despite of other reconstructive systems. Moreover the use of a device, as that described, for an easy anchorage of the myotendinous structures, allows a quick functional recovery offering the patients considerable advantages for their social life.

Zirconia has considered a good material for manufacturing of ball heads in total hip replacement due to high mechanical properties of this ceramic material. However in the literature the problem of heads biocompatibility is still debated. The Authors reported their experience in ten years of research on the biological properties of this material. In vitro tests were performed onto materials in form of powders, analyzing the inhibitory effects on human lymphocyte mitogenesis, and in form of plates measuring adhesion and spreading of 3T3 fibroblasts. A mutagenic test was also performed. In vivo tests were performed by injection of powders in mice and evaluating the survival of animals according to ASTM F – 750. We also inserted ceramic in form of cylinders into proximal tibial metaphysis of NZW rabbits and analysed local and systemic reaction due to material diffusion. We also developed a system of production of Zirconia particles by inserting ceramics under patellar tendon of NZW rabbits.

In vitro tests showed that Zirconia powders and plates induced a similar effect of Alumina ones; no mutagenic effect were observed using our samples, demonstrating that Zirconia has no carginogenic effects. In any case the diffusion of particles didn’t show modifications into internal organs (lung, kidney, liver, spleen) of mice and rabbits. In time (one year after operation) the connective tissue present at bone ceramic interface is transformed into lamellar bone.

Our experience demonstrates that Zirconia may be considered a good material for prosthetic implants.

The Authors analysed two cases of catastrophic failures of Total Hip Prostheses due to the disruption of the PE inlay and the Ti-alloy metal back of the acetabular components. In the cases reported the PE inlay (4 mm in thickness) was coupled with a 32 mm in diameter Alumina ball heads. At time of revision the alumina ball heads showed many black marks due to the contacts with the Ti-alloy metal back. The sockets showed severe damages, concentrated in the superolateral zone. The PE inlays were disrupted. Almost a third of the metal back is missing. A large metallosis was also visible in the membrane at the interface between implant and bone. Histologic sections showed a large amount of metallic debris in a pseudovillous membrane. At higher magnification oligonuclear cells in a rich in vessels stroma were in contact with metal particles. PE debris with the characteristic birifrangent aspect to the polarised light microscope was contained into polynuclear giant cells. SEM showed that the size of 25% of particles was less than 1 μm, while the size of 53% of wear debris is in the range from 1 to 5 mm. EDAX confirmed that these particles consisted of Ti alloy. The Authors analysed the possible roles of different factors in the etiology of this cup failures and concluded that in both the cases analysed the initiator of the failure was the size selection of the prosthesis, and in particular the PE thickness, followed by the positioning of the acetabular component. The deformation of the PE inlay leads to rupture of the inlay itself, followed by the direct contact between the Alumina ball head and the titanium alloy cup, causing the disruption of the Ti-alloy metal back, with massive release of wear debris in the surrounding tissues.

To evaluate the osseointegration enhancement, a consecutive randomized series of 50 on a total of 483 cementless titanium prostheses were prospectically studied. The features of the stem were the following: tapered, straight, low-profile neck, metaphyseal and hystmic fit, proximal 1/3 hydroxyapatite coated (HA) and titanium porous coated (PC). The acetabular component was hemispherical, titanium porous coated. A zircornia or Co/Cr head (28mm) was used. Female were 53% and average age 65. The general diagnosis was ostheoarthritis, congenital hip dysplasia, fracture, aseptic loosening, osteonecrosis, previous femoral osteotomy, previous pelvic osteotomy. Clinical objective assessment was based on the HHS. A patient oriented evaluation (Womac and SF12) was obtained. Radiological assessment was based on the Engh’s method. The general and prospectical group results have been evaluated.

In all the groups the HHS, Womac and SF12 questionnaires showed a statistically significant improvement in quality of life. Consistent evidence of proximal bone ingrowth were present in 100 % (HA) and 96 % (PC), stable proximal fibrous ingrowth in 4 % (PC). Cortical hypertrophy (50 % zone 3–5), stress shielding (56 % zone 1) and pedestal ( one case) were assessed. Nor osteolysis neither subsidence were identified. No significant general complications such as infections or periprosthetic fractures were observed. The use of HA seems to improve the mechanism of osseointegration and earlier clinical outcomes, even if this difference is not significant. Patient oriented evaluation and radiographic assessments confirmed the reliability of this cementless prosthesis. Less osteolysis could be predicted in the future, according to the reported results of other authors in the HA coated stems.

Aims: Primary non-Hodgkin lymphoma of bone account for 5% of extra nodal lymphomas. The Authors report their experience referring to the results obtained with a multidisciplinary approach.

Materials: 18 cases of lymphoma of bone were included. Medium age was 63 yrs. All cases have been classified according to the REAL classification system. Patients have been staged with: total body CT scan, bone marrow aspirate, bone marrow biopsy, LDH serum level, skeletal survey and MRI of the skeletal segments involved. We treated 10 cases with solitary localization and 8 with multiple ones. Three patients presented with a pathologic fracture at diagnosis.

Chemotherapy protocols were:

MACOP-B < 60 yrs.

VNCOP-B > 60 yrs.

Seven patients received the PROMACE-CYTABOM protocol.

13 patients received EBRT (40 Gy). Ten patients received a surgical treatment: internal fixation in 7 cases and of spine stabilization in 3 cases

Results: At a medium follow-up of 40 months overall survival was 34,6 months and 14,5 months respectively for solitary or multiple localizations. Surgical treatment has been useful in improving performance status and in some cases to obtain a better control of the disease.

Discussion: In our experience bone lymphomas have always a high grade histology. Chemotherapy constitutes the treatment of choice. Surgical treatment have to be considered as a support treatment. Prognosis is worse in multiple localizations

Aim: This study evaluated the complication rate and surgical outcome following medial femoral neck fractures, in elderly patients over 75 y, treated by biarticu-lar endoprosthesis. Methods: We followed prospectively 100 patients over 75 years old consecutively operated in our department of clinical orthopaedics at Catholic University of Rome for subcapital femoral fractures graded as Garden 3 or 4. In the study were also included patients affected by senile dementia and Parkinson disease. Patients were operated on by several surgeon of different experience in the þeld, we evaluated the time needed for the intervention, blood loss, survival rate at 1 months. Outcome was evaluated on the basis of walking recovery rate and pain. Bed ridden patients were evaluated only for residual pain after surgery. Results: Mean time interval between trauma and surgery has been 3,96 days. The intervention lasted 45 minutes in average (range 35 Ð 70 minutes). Blood loss has been limited. Return to walking with assistance has been achieved in fourth postoperative day. Pain disappeared in almost every patient. Dislocation of prosthesis was observed in 2 patients. Survival rate at one month was 89%.,Conclusions: Biarticular endoprosthesis in our experience demonstrated to be an effective mean for treatment in the elderly patients and above all in the neurological patients.

Aim: The differential diagnosis between chondroma and grade I chondrosarcoma still represents a challenge. There are always cases in which a perfect diagnosis can’t be done for sure. This cases are defined in literature with different synonyms such as: borderline chondrosarcoma, grade 0 chondrosarcoma, atypical enchondroma or in situ chondrosarcoma. Enchondroma are benign lesions that do not require a surgical treatment. Low grade chondrosarcoma is a malignant tumour that can recur and also if in a low percentage of cases can metastasize. Methods: The Authors reviewed 22 cases of chondrosarcoma of the limbs for clinical, radiographycal and histological features. Results: Pain was present in 80% of cases of low grade chondrosarcoma, while was absent in enchondroma. Radiographic analysis was not significative. Bone scan was often positive in low grade chondrosarcoma as in enchondroma. Histology demonstrated a permeative pattern in chondrosarcoma with infiltration of the bone trabeculae. Conclusions: Only the complete evaluation of the patient resulted in a correct diagnosis. Follow-up of patients confirmed our findings