Since 1977 we did implant ceramic on ceramic THR in younger and active population. In 1991 we published (JBJS B N°4) data's in a consecutive group of patients under 50 years of age.

What about the same patients for more than 30 years? Eighty-six hips in 75 patients, 41 males 34 females, mean age 43 (18 to 50), mean weight 68 kg (36 to 100), Charnley class: 38 A, 28 (38 hips) B, 9 patients (10 hips) C. Sixty-six primary procedures, 20 revisions (18 failed arthroplasties: 6 THR, 5 resurfacing, four single cup, two hemiarthroplasty, one bipolar), one after acetabular fractures. Four hips previously infected.

Eight Patients deceased (8 hips) prosthesis still in place, ten lost to follow-up before 2 years, eight hips in 8 patients were revised before the review, partially followed: from 2 to 20 years: 35, completely followed: 25 hips in 23 patients resuming in: No pain in 20, slight pain in 2, severe disability in 3 not related to the hip, no radiolucent lines in 22, radiolucent lines in 3, no osteolysis in 25.

Revision for: early sepsis in one, socket loosening in 8 (3 revisions cases), femoral head fractures in 2: one extra small head (22mm) for Crowe 3 DDH, one fractured at 24 years.

Inertness, stability related to fibrous tissue generation, no noise.

Introduction and Objective

Despite pure alumina have shown excellent long-term results in patients undergoing total hip arthroplasty (THA), alumina matrix composites (AMCs) composed of alumina and zirconium oxide are more commonly used. There are no comparative studies between these two different ceramics. We performed a retrospective case-control study to compare results and associated complications between AMC from two manufacturers and those with pure alumina from another manufacturer.

Fracture risks are the most common argument against the use of Ceramic on ceramic (CoC) hip implants. Question: is ceramic material at risk in case of severe local trauma?

Over a long period, we tried to identify patients with a CoC prosthesis (Ceraver Osteal°)who did sustain a trauma. This was conducted in three different institutions.

Eleven patients were found: 9 males and 2 females aged 17 to 70 years at time of index surgery. Accident occurred 6 months to 15 years after index: one car accident, five motorcycle accident, five significant trauma after a fall, including one ski board accident. Consequences of these trauma were: six fractures of the acetabulum with socket loosening in 4 that needed revision, two femoral shaft fracture, one orifed and one stem exchanged, one traumatic hip dislocation associated to loosening of the socket revised at 10 years, and one traumatic loosening of the socket. Ten had no consequence on ceramic integrity. One experienced a fracture of the patella from a dashboard trauma, a liner shipping was discovered during socket revision 2 years later. This is the only case of possible relation between trauma and ceramic fracture. In a more recent longitudinal study on 1856 CoC prosthesis performed from 2010 to 2021, 29 severe traumas were identified with no consequence on Ceramic material.

From this limited case study, it can be assumed that Pure Alumina Ceramic well designed and manufactured, will not break after a significant trauma.

The objective of this study was to determine whether the bearing surface is a risk factor for revision after late dislocation in total hip arthroplasty (THA).

Data from primary THAs were extracted from the New Zealand Joint Registry over a 13-year period. The mean age of patients was 68.9 years; 53.2% were female. The surgical approach used was posterior in 66% of THAs, lateral in 29% and anterior in 5%. There were 53,331 (65.1%) metal-on-polyethylene THAs, 14,093 (17.2%) ceramic-on-polyethylene, 8,177 (10.0%) ceramic-on-ceramic, 461 (0.5%) ceramic-on-metal, 5910, and (7.2%) metal-on-metal.

The primary endpoint was late revision for dislocation, with ‘late’ defined as greater than one year post-operatively. 73,386 hips were available for analysis. The overall revision rate was 4.3% (3,130 THAs), 1.1% (836) were revised for dislocation. Only 0.65% (470) hips were revised for dislocation after the first post-operative year.

The unadjusted hazard ratios (HR) showed significantly higher rates of revision for dislocation in ceramic-on-polyethylene (HR 2.48; p=0.001) and metal-on-polyethylene (HR 2.00; 95% p =0.007) compared to ceramic-on-ceramic. However, when adjusted for head size, age and surgical approach, only ceramic-on-polyethylene (HR 2.10; p=0.021) maintained a significantly higher rate of revision, whereas metal-on-polyethylene approached significance (HR 1.76; 95% p = 0.075).

In New Zealand, dislocation is the most common reason for revision, ahead of aseptic loosening of the acetabular component. The relationships between bearing materials and risk of revision for late dislocation is controversial. However, in this study ceramic-on-ceramic shows lower risk rates for revision than other bearing surface combinations. Low wear and less debris, limited peri-articular inflammatory reaction and an healthy fibrotic pseudo-capsule are potential factors determining long-term stability of the hip joint.

Introduction

Acetabular fractures management is controversial since, despite a good anatomical reduction, clinical outcome is not satisfactory very often and the probability of a total hip arthroplasty (THA) is high. Surgical treatment include long operating times, large approach, blood loss, neural and muscle damage, and a high risk of failure and secondary osteoarthritis related to bone necrosis, cartilage damage, and bone loss.

We hypothesized that the acetabular fracture management affected the clinical and radiological outcome of THA after posttraumatic arthritis.

Different pathologies, deformities, bone defects, previous surgeries and polyethylene wear limit the survival of total hip arthroplasty (THA) in young patients. We compare preoperative status and outcome in 171 young and very young patients (207 hips) who underwent a ceramic-on-ceramic THA. Sixty-three (77 hips) were less than 30 years old (group 1) and 108 (130) were between 30 and 40 years old. Mean follow-up was 11.3 years. Two-way ANOVA with repeated measures were used to analyse clinical and radiological changes.

Juvenile rheumatoid arthritis (JRA) was the most frequent diagnosis in group 1 and avascular necrosis in group 2. Charnley class type C, low activivity, previous surgery and osteoporotic bone were more frequent in group 1 patients. There were 2 cup revisions for aseptic loosening in group 1 and 4 in group 2. Survivorship analysis at 15 years was 96.7% (95% IC 92.2 a 100) for group 1 and 96.1% (95% IC 92.2 to 100) for group 2 (p=0.749). Despite the worse preoperative status in group 1 patients, clinical outcome was similar in both groups. Severe dysplasia had the worst clinical result and avascular necrosis the best. Patients with Charnley class C and JRA showed the most improvement. Radiographic reconstruction of the abduction angle was worse in group 1 (p=0.02). No osteolysis or complications derived from ceramic use were found.

We conclude that despite the worse preoperative status in group 1 patients, clinical and radiographic results were good in both groups of patients who received a ceramic-on-ceramic THA.

Recent studies about hip stability after total hip arthroplasties (THA) concerned differences regarding bearings: ceramic on ceramic (CoC) presenting less dislocations on the long term compared to metal or ceramic on polyethylene. The hypothesis is a difference in the healing process of periarticular tissues, with a stronger fibrous tissue for the first one, and more foreign body reaction, joint effusion with the others.

NMR Imaging of the pelvis showing both hips using novel MR MAVRIC program for metal artefacts suppression, were performed in 10 patients, 15 THA and 2 non-pathological contralateral hips. Eight hips had CoC bearings, 3 of which were impacted cementless bulky ceramic implant, and 5 had a metal back. 7 hips had CoP bearings, 4 of which were cemented.

Native capsules showed a mean thickness of 6.6mm. For CoC bearings, capsule thickness ranged from 7mm to 9.6 mm with a mean thickness of 8mm. For CoP bearings, capsule thickness ranged from 3mm to 8.4mm, with a mean thickness of 6.1mm. Neocapsule appeared clearly in all COC bearings observed, while for CoP, sometimes it was less dense with fatty aspect, 3 hips out of 7 having a very thin capsule under 4mm.

It is possible to observe and quantify new capsule after THR and measure differences although not significant regarding bearings on limited number of samples. More patients might be included, but the tendencies observed here might explain better long term stability in vivo observed with Coc.

Introduction

In the year 1977 we started to use ceramic on ceramic total hip (Ceraver*). The prosthesis was cemented on both sides. Ceramic was medical grade with relative large grains and high porosity. The stem was made of titanium alloy smooth and oxidized.

In 1990 we published the results of 86 hips in 75 patients who were less than 50 years of age at time of operation (1). Recently we tried to reach the same patients, looking specifically to those who could have more than 20 or 30 years follow-up.

Starting in 1977 a new cemented stem made of titanium alloy (with vanadium) was designed regarding some principle: rectangular shape, smooth surface covered with thin layer of titanium oxide, filling the medullar cavity. As a consequence: a thin layer of cement. It was designed with a collar. Initial Cementing technique used dough cement, vent tube and finger packing; then we applied cement retractor low viscosity cement and sometimes Harris Syringe. At the moment we went back to initial technique plus a cement retractor made of polyethylene. Many papers looked at long term follow up results depicting about 98 to 100 percent survivors at 10 years and 95 to 98% at 20 years (Hernigou, Hamadouche, Nizard, El Kaim).

Clinical as well as radiological results are available.

Radiological results depicted some radiolucent lines that appeared at the very long term. They could be related to friction between the stem and the cement. As advocated by Robin Ling, he called “French paradox” the fact that if a cemented prosthesis is smooth and fills the medullary cavity, long term excellent results could be expected.

This was the case with stainless steel Kerboull shape, the Ling design (Exeter)and the Ceraver design.

The majority of these stems were implanted with an all alumina bearing system. And in some occasion, when revision had to be performed, the stem was left in place (108 cases over 132 revisions)

Our experience over more than 5000 stems implanted is outstanding (see figure 1: aspect after 30 years).

Discussion other experience with cemented titanium stem were bad (Sarmiento, Fare). We suspect that this was related either to the small size of this flexible material, or to the roughness of its surface.

If one uses titanium cemented stem it must be large enough and extra smooth.

Purpose of the study: Oestrogen depletion leads to osteoclastic hyperactivity and subsequent postmenopausal osteoporosis. Little is known about interactions with bone absorption induced by wear particles from joint bearings. The purpose of this study was to evaluate bone response to polyethylene (PE) particles in a mouse model of oestrogen deficiency.

Material and methods: Particles of PE were implanted in the calvaria of seven non-ovariectomised mice and in seven ovariectomised mice (OVX). Fourteen mice were operated on without implantation of the particles (7 non-OVX and 7 OVX, control groups). The mice were sacrificed at two weeks. The crania were studied under a microscanner and histologically without decalcification.

Results: The microscanner showed that particles of PE induced a significant decrease in bone thickness in non-OVX mice (p=0.04), while the thickness remained unchanged in OVX mice who had received the particles (p=0.40). After implantation of the PE particles, the number of osteoclasts per mm of bone perimeter was 2.84±1.6 in the non-OVX mice and 1.74±1.3 in OVX mice (p=0.004). Compared with controls, the mean loss of bone was 12±10% in the non-OVX mice versus 4.7±0.9%in the OVX mice (p=0.004).

Discussion: The volume of osteolysis induced by PE particles was smaller in OVX mice compared with non-OVX mice.

Conclusion: These results suggest that a deficit in oestrogens has a protective effect against bone adsorption induced by PE particles.

Hard-on-hard bearing surface have been accepted as a valuable alternative for young and active patients needing a hip replacement because these combinations are resistant to wear. Initial development of alumina-on-alumina bearings faced complications such as fractures, and socket loosening. But, with the increasing number of prostheses implanted, noise occurrence appeared as a new complication. The primary aim of the present survey was to quantify the prevalence of having noise in a population receiving alumina-on-alumina hip arthroplasty.

Two hundred and eighty-four ceramic-on-ceramic hips were performed in 238 patients (126 males and 112 females) from January 2003 to December 2004. The average age at the index operation was 52.4 ± 13.4 years (range, 13 to 74 years). We used the same type of prosthesis for all patients manufactured in all cases by Ceraver-Osteal^®. Clearance between femoral and insert was between 20 and 50 microns in order to achieve minimal wear. The survey was conducted by an independent surgeon who did not participated in patients care during the last 6 months of 2007. He interviewed the patients by phone with a standardized questionnaire (appendix) that aimed to assess if noise was present and the characteristics of this noise if present. No suggestion was done on how they could describe the noise and they felt free to use the word that they considered to be the most adapted. Satisfaction was evaluated asking if the patient was very satisfied, satisfied or dissatisfied with its prosthesis.

When the noise was present, the X-ray was independently evaluated to assess if sign of component fracture was present.

Four patients (six hips) died of unrelated cause during the follow-up. Three patients (three hips) lived outside France and could not be followed (1.3%). Nine patients (ten hips) could not be traced and are considered lost to follow-up (3.8%). Two hundred and twenty-two patients with 265 hips were therefore surveyed. Among these 265 hips, 28 experienced noise generation (10.6%). It was defined as a snap for 6 patients, as a cracking sound by 6, as rustling by 6 patients, as a squeaking by 7 patients (2.6%), a tinkling by 2 patients, one patient was unable to define the sound she felt. No factor related to the patient influenced the occurrence of noise. Twelve patients were dissatisfied with the result of the hip prosthesis, 5 of them experienced noise (41.7%); 210 were satisfied or very satisfied 23 of them experienced noise (11%); this difference was significant (p=0.002). No patients required revision for noise.

The origins of noise occurrence are unknown but several hypotheses can be suggested.

Squeaking may be due to absence of sufficient lubrication. Other types of noise can be due to microseparation, occult dislocation, impingement between the femoral neck and the acetabular rim but demonstration remain an issue.

Introduction: While an increasing number of authors have reported on the long-term results of primary alumina total hip arthroplasty (THA) [1], strategies for revising a ceramic-on-ceramic THA are debated in the literature. According to some authors [2], the reimplantation of a ceramic head on a well-fixed femoral stem is inadvisable, as it may lead to a fracture of the newly implanted head. The aim of the present study was to evaluate the incidence of this specific issue, and to report on the clinical and radiological results of the revised hips.

Methods: Between January 1977 and December 2005, 138 consecutive alumina-alumina revision hip arthroplasties were performed in 127 patients. There were 79 women (62.2%) and 48 men (37.8%), with an average age of 67 years (range, 32–91 years). Among these, an isolated acetabular revision was performed in 108 cases. The reason for revision was aseptic loosening of the acetabular component in 98 hips, pain in 7, fracture of an alumina liner in 2, and recurrent dislocation in 1. The revised socket was a cemented alumina in 56 hips, a threaded screw-in titanium with an alumina core in 34, a pressfit titanium with an alumina core in 11, and bulk alumina in 7. Acetabular bone stock losses were classified according to the AAOS system. Most of the hips had a contained type II defect (86%). In all cases, the femoral stem was left in place and the acetabular component alone was revised. At the time of revision surgery, an aluminaalumina combination was implanted in 27 hips, an aluminapolyethylene combination in 56, a metal-poly-ethylene combination in 15, and a zirconia-polyethylene in 10. Overall, a ceramic head was reimplanted on a used femoral taper in 59 cases. Acetabular reconstruction with allografts supported with the Kerboull acetabular reinforcement device was performed in 31% of the hips.

Results: The mean follow-up period was 78 ± 37 months. Thirteen patients (15 hips) died a mean 37 months after surgery. Sixteen patients were lost to follow-up. Postoperatively, five hips had a recurrent dislocation, 2 a deep infection, 9 a trochanteric nonunion (21,3%), 6 a transient nerve palsy. 18 hips required a re-revision surgery, 12 of which for aseptic loosening of the acetabular component. Among the 59 ceramic heads implanted on a well-fixed stem, no fracture of the head occurred at a mean 81 months follow-up. Of the original 108 hips, 77 were available for clinical evaluation and 75 for radiological evaluation at least 2 years after surgery. The mean Merle d’Aubigné score increased from 10.1 ± 2.1 to 16.7 ± 1.1 at the latest follow-up (p< 0.001). Forty-five hips were graded excellent or very good (60%), 26 good (34,6%), 3 fair (4%), and 1 poor (1.3%). When revision for aseptic loosening was considered as a failure, the overall survival rate at 8 years was 96.3 ± 1.8%.

Discussion & Conclusions: In the present study, aseptic loosening of the acetabular component was the main reason for revision surgery. Osteolysis around ceramic implants was moderate and was related to the migration of the socket. Among the ceramic heads implanted on a used titanium trunnion, no fracture was observed. This approach is possible, in so far as careful inspection does not show any major imperfection of the morse taper [3]. As for other bearing surfaces, the management of aseptic loosening of al-al prostheses is based on the amount of osteolysis around the loosened socket.

Femoral revision is frequent, due to femoral loosening, thigh pain, recurrent dislocation, osteolysis or sepsis. Whatever the reason, with the exception of some difficult septic cases, our strategic approach is similar. Some of our expertise concern femoral stem retrieval. Our reconstruction strategy is different if we are revising total hip in active and young patient or if it is an old and inactive one.

First step is always an large “en bloc” tissue excision. For old and inactive, it is sometimes possible to retain the stem if not loosed and perform a “in cement” cementation; In this group we select usually metal or alumina on polyethylene couple and cemented implants; In young and active, we select alumina on alumina combination which resumed in cementless acetabular fixation, and cementless or cemented stem.

Stem retrieval of a well fixed cementless stem is performed via a large transtrochanteric approach associated with a transfemoral one. Repair is performed using cerclage and long cemented stem.

Cement retrieval is performed since 9 years using Ultra sound (Oscar*) material, which in our hand is very successful specially for cement retractor retrieval. Then medullary canal is reamed in order to get a bloody healthy bone receive either a cemented or sometimes a cementless stem, depending on the bone quality.

To compensate femoral bone destruction and enhance cemented stem fixation, we used a modified Ling technique replacing allogenic morcellised bone by hydroxyapatite granules. Granules of 5 mm in diameter are made of 70% HA and 30% of β TCP. Mechanical resistance is excellent and biological activity is high. Thus stem stability can be obtained easily. This can be done either with a cemented or a cementless stem (about 60 cases).

In case of very severe bone loss and osteolysis, we performed massive allogenic bone transplant associated with long cemented stem and distal HA granules with cement.(17 cases).

As we usually performed one stage revision for septic cases, strategy is not different; It is only in selected cases with many sepsis recurrence and specially aggressive bacteria that we performed a two stage procedure.

Purpose of the study: Several studies have demonstrated the usefulness of mesenchymatous stem cells (MSC) for cell therapy aimed at favoring bone tissue healing. Bone morphogenesis proteins (BMP) orient MSC towards osteoblastic differentiation. Since they are rapidly degraded in the organism, these proteins require a continuous release system to potentialize their biological activity in a controlled localized manner. We evaluated the usefulness of using the electroporation technique to insert a BMP transgene into the MSC of rats to enable sufficient transient expression of BMP genes to enable satisfactory bone healing. We first developed electroporation conditions for rat MSC and checked cell viability after the electric shock. Secondly, in order to obtain quantitative and/or temporal BMP expression, we tested the influence of different promoters on transcription actvity.

Material and methods: To determine the electroporation parameters, MCS were transfected with the pCMV-LacZ plasmid using two electric impulsions: a series of eight 100 impulsions/μs at high voltage (900-170V/cm) followed or not by a series of eight 12.5 ms low-voltage impulsions (60 V/cm). After determining the electroporation conditions, six plasmids carrying different promoters were electroporated.

Results: The best transfection rate in rat MSC was obtained with a series of 8 impulsions at 1500 V/cm. Before the electrical shock, the suspended rat MSC had to be incubated at ambient temperature to favor cell survival. Proliferation of electroporated cells was comparable to that of non electroporated cells. Surprisingly, addition of low-voltage pulses significantly decreased the efficacy of transfection. In addition, MSC transfected with the promoters GAPDH and beta-actin presented a beta-galactoside activity (at 48 h) superior to that obtained with the pCMV promoter.

Discussion: After optimization of these parameters, we demonstrated that MCS can be effectively transfected by electroporation. The following steps will be to check for long-term expression of beta-galactoside by electroporated MSC, transfection of MSC with plasmids or the BMP-2 gene controlled by these same promoters and monitoring promoter activity as a function of the stage of MSC differentiation.

Purpose of the study: The objective of this study was to establish an experimental sheep model for a surgical procedure which has been clinically successful for repairing major loss of bone stock: the Masquelet technique.

Material and methods: A 25 mm bone defect was created in a metatarsal bone then filled with a cement filler. After six weeks, the cement was removed after opening the neoformed pseudosynovial membrane. The cavity was left empty in group 1 (n=6) or filled with a morcelized cancellous autograft harvested from the iliac crests in group 1 (n=6).

Results: The surgery was well tolerated in all animals which were able to used the injured limb the day after the operation. Radiographic images and histological findings 24 weeks after surgery demonstrated that healing had not been achieved in all of the animals in group 1. Inversely, healing was achieved in all animals in group 2 at 24 weeks. Immunohistochemistry of the neoformed pseudosynovial demonstrated :

an abundant vascular network,

Conclusion: The sheep metatarsal model is a model of critical size with low morbidity. This model could be used to:

evaluate new therapeutic strategies for bone regeneration in conditions close to clinical situations,

The presence of a pseudosynovial membrane might:

be a barrier against the diffusion of bone morphogenetic proteins outside the lesion and

Purpose of the study: Complex fracture-dislocation of the elbow, and subsequent surgical treatment, is often the source of a stiff joint. The purpose of this study was to assess the efficacy of a therapeutic protocol combining systematic insertion of a dynamic external fixator allowing early mobilization of the elbow with restitution of the radial height and the coronoid process.

Material and methods: This consecutive series of ten patient, six men and four women, mean age 49 years, age range 27–67 years, underwent surgery from 2002 to 2004. Three patients presented a posterior Monteggia fracture (two type IIA, one type IId associated with comminutive fracture of the trochlea), four patients presented a dislocation associated with a Masson 4 fracture of the radial head and two presented inveterated dislocations diagnosed three weeks after the traumatic event. In all, seven patients presented a fracture of the radial head and six a fracture of the coronoid process. For all patients, the operation consisted in stabilization with a dynamic external fixator of the elbow associated or not with restoration of the radial height with a radial head prosthesis (n=4) and reconstitution of the coronoid process (n=6). The lateral ligaments had to be reinserted in four elbows. The comminutive fracture of the rochlea was treated with an iliac crest graft.

Results: One patient died early. One patient presented pin tract infection and four developed heterotopic ossifications. At mean follow-up of twelve months, outcome was excellent in our patients, good in four, fair in one (Mayo clinic classification). All patients had a stable elbow. The mean range of motion was 89° flexion-extension and 145° pronationsupination.

Conclusion: In this series, systematic use of external fixation for complex fracture-dislocation of the elbow joint yielded satisfactory results when the element stabilizing the joint were appropriately restored and when rehabilitation was undertaken early.

Purpose of the study: Cell therapy proposes to fill gaps left by bone stock loss using osteocompetent cells (mesenchymatous stem cells, MSC). Preclinical results have been promising but still require improvement particularly concerning stress to the MSC during in vivo implantation. Stress results from sudden transfer i) from oxygen medium (21% O2) to a hypoxic medium (0–5% O2 because O2 diffusion is limited to 200 mm from a blood vessel), ii) a cell support to an osteoconductor support, et iii) a rich medium (fecal calf serum, FCS) to a medium with a limited supply of nutrients, hormones and growth factors diffusing from the environing biological fluids. The purpose of this study was to evaluate in vitro the impact of these different factors on MSC survival.

Material and methods: Human MSC(hMSC) harvested from bone marrow (n= 5 donors) and sheep MSC (sMSC) obtained with a preclinical model (n = 5 animal donors) were exposed for 48 h(hMSC) or 72h (sMSC) to the following transfers: i) rich medium (10% FCS) to poor medium (1% FCS), ii) plastic support to osteo-conductor supports (alumina, calcium carbonate), and iii) oxygen medium (21% O2) to hypoxic medium (6% O2). sMSC were also exposed to prolonged hypoxia (48–120h). Cell death was determined using image analysis after live/dead cell staining.

Results: The results demonstrated that MSC are: i) sensitive to a decrease from 10% to 0% FCS; 14% death of hMSC and 17% death of sMSC), ii) sensitive to transfer onto osteoconductor supports (sMSC on calcium carbonate: 23%), iii) very sensitive to prolonged hypoxia (120h) when combined with decreased FCS (sMSC: 23%; hMSC: 98%). A complementary study on the influence of hypoxia on differentiation properties of surviving sMSC is under way.

Conclusion: If the in vivo results concord with the in vitro results, i.e. if massive cell death is observed 4 days after implantation due to hypoxia, the current transplantation conditions will have to be revisited. Acceleration of neovascularization of in vivo implants which would shorten the period of hypoxia should allow better survival of implanted sMSC.

Purpose of the study: Bone morphogenetic proteins (BMPs) are osteoinducing proteins which play a primordial role in bone repair. To obtain optimal mineralization in vivo, high doses of heparin binding growth factor must be used. Studies have demonstrated that functionalized dextranes (FD) present affinity for heparin binding growth factor. We studied the capacity of dextrane derivatives to interact with BMP-2 and potentialize its biological activity in vitro.

Material and methods: Different soluble FD were obtained by random substitution of carbosymethyl (CM), benzylamide (B) and sulfate (Su) groups on native dextrane chains. Gel electrophoresis was used to study the affinity of the anionic FDs for BMP-2. The effect of polymers on osteoinduction activity of BMP-2 was evaluated by histochemistry. ALP (an early marker) synthesized by mypoblasts C2C12 were dosed seven days after injection in presence of BMP-2 associated or not with polymers. IN addition, expression of osteocalcin (late marker) was quantified by RT-PCR.

Results: Electrophoresis demonstrated that DMCB and DMCBSu interacted with BMP-2. These interactions appeared to increase with B level but decreased with Su level. We worked with FD1, a DMCB with a high affinity for BMP-2. The ALP activity was clearly potentialized when BMP-2 was associated with heparin and even better with FD1. Expression of osteocalcin was also amplified with the FD1-BMP-2 association. The influence on the biological activity of BMP-2 of FD, presenting different degrees of substitution, was also tested. Only FDs containing a high concentration of B expressed affinity for BMP-2, potentializing the biological activity of the protein.

Discussion: Dextanes functionalized with a high rate of benzylamide substitution interact with BMP-2 while sulfate substitution limits such interaction. Only FDS which interact with BMP-2 can potentialize the protein’s biological activity in vitro. Two hypotheses can be put forward: i) FD presents BMP-2 to its receptor cell, ii) FD protects BMP-2 from proteolytic degradation or capture by antagonists. The capacity of FD1 to potentialize the biological activity of BMP-2 could be a way of reducing the quantity of growth factor needed for optimal bone repair.

Purpose of the study: Computer assisted surgery for total knee arthroplasty is widely used in Europe. The reliability of these systems appears to be very good with bone cuts within 3° of the planned mechanical axis. Nevertheless, the relationship between intraoperative measurements provided by the navigation system and the postoperative gonometry can be used to assess the quality of realignment. The purpose of this work was to determine this relationship.

Material and methods: Thirty-three knees operated on with the Navitrack® system were assessed. Two senior operaters performed all procedures. An Omnia® cemented prosthesis with an ultracongruent fixed plateau was used in all cases. Intraoperative measurements wer made with the definitive prosthesis after cement solidification without stress on the knee. Postoperative gonometry was undertaken when the intraoperative flexion had disappeared six weeks to six months after the operation. Gonometric measurements were made by an independent operator using a computerized system operating on digitalized x-rays. The gonometric protocol had been standardized previously and only the gonometric measurements in compliance with this protocol were retained for analysis. The difference between measurements was analyzed with the t test for paired variables. Search for correlations was also performed.

Results: On average the intraoperative deviation was 0.8±0.8° (3° valgus to 2.4° varus). The postoperative gonometry showed 1.7±1.1° (3.4° valgus to 4.3° varus). The mean difference between the intraoperative axis and the measured postoperative axis was significant (p< 0.0001). There was no significant correlation between intraoperative and postoperative measurements.

Discussion: Computer-assisted navigation systems have their limitations which should be measured. The present findings would demonstrate a significant difference of minimal amplitude between the intraoperative measurement and the postoperative gonometry. Although the clinical pertinence of this difference remains to be demonstrated, it must be kept in mind for safe use of these navigation systems.

Since 1977 we did implant all alumina (Al2O3) bearings total hip prostheses. A lot of data were documented concerning tissue reaction, in vivo wear behaviour, fractures, and clinical outcome. Ceramic materials retrieved at revision were analysed. In some cases, wear was as low as a few microns for a 15-year period in use. This is two thousand times less than a regular metal on polyethylene sliding couple. and 100 times less than a metal on metal prosthesis. Fracture mechanism is related to crack propagation into the material. During the first period, the fracture rate was in the range of 2%; it then dropped to less than 0.1 %. Few fractures could not be explained by technical or design mistakes. Clinical outcome: More than 4000 total hips in selected young and /or active patients were implanted. In a recently reported series of consecutive patients operated by P.Boutin during the year 1980, 118 hips in 106 patients were included. Mean age was 62 years. At the twenty-year follow-up evaluation, forty-five patients (fifty-one hips) were still alive and had not been revised, twenty-five patients (twenty-five hips) had undergone revision of either or both components, twenty-seven patients (thirty hips) had died from unrelated causes, and nine patients (twelve hips) were lost to follow-up. The mean Merle d’Aubigné hip score was 16.2 ± 1.8 at the latest follow-up. Survival of the cup at twenty years with revision for any reason as the end-point was 85.6 percent for cementless cups versus 61.2 % for cemented cups, respectively. Survival of the stem at twenty years with revision for any reason as the end-point was 84.9 % for cementless stems versus 87.3% for cemented stems. Wear of the prosthetic components was undetectable on plain radiographs. No fracture of the alumina socket or head was recorded. Another study concerned a more recent design of the socket which consisted in a metal back titanium alloy shell covered with a pure titanium mesh with an alumina liner. The nine year survival rate was 98.4% with revision for aseptic loosening as the end point. Conclusion This alumina on alumina bearing provides interesting results without any physical limitation specially in young and active patients.

Effectiveness of total hip arthroplasty (THA) for acute fracture of the femoral neck is still debated. The purpose of this retrospective controlled study was to compare the results of THA done for fracture of the femoral neck with a similar group of matched THAs done for osteoarthritis (OA).

From 1993 to 2000, 25 patients (25 hips) had THA for displaced femoral neck fracture. There were 18 women and 7 men, with a mean age of 73+/− 8.5 years (range, 55 to 93 years). The control group was composed of 25 patients (27 hips) who had THA for primary OA. Patients were matched for age, sex, medical comorbidity, surgical approach, prosthesis, and surgeon. Cemented implants with a Me-PE couple were used in the great majority. All patients had radiographic assessment. Functional results were rated according to the grading system of Merle d’Aubigné.

One patient (one hip) was lost to follow-up in each group. The mean follow-up was 6 years (range, 3.5 to 10 years). No revision was performed in this series. Complications included one postoperative dislocation in both groups. At the last follow up evaluation, 21 hips and 23 hips were classified excellent or very good in the “fracture” group and in the control group respectively. No progressive radiolucent line and no osteolysis were recorded. Mean annual PE wear was 0.096 +/− 0.094 (range, 0 to 0.26 mm) in the studied group compared with 0.125+/− 0.095 (range, 0 to 0.24 mm) in the control (p=0.30).

THA for acute femoral neck fracture and THA for OA provided comparable mid to long term results in elderly patients.

Purpose: Total hip arthroplasty after failure of femoral osteotomy raises high risk of complications. Outcome has been controversial. The purpose of this retrospective analysis was to evaluate the difficulties and results.

Material and methods: Between March 1974 and January 1995, 68 patients (82 hips), 51 women and 17 men, mean age 59±11.5 years (32–84) underwent surgery. Initial indications were mainly acetabular and/or femoral dysplasia (n=47 hips) or congenital dislocation (n=21 hips). Mean time between osteotomy and arthroplasty was 13.8±8.4 years (10 months-45 years). We used cemented titanium femoral stems (Ceraver Ostal) with an alumina (n=66) or polyethylene (n=16) cup. An alumina-alumina bearing was used in 67 hips (81%). Functional outcome was assessed with the Postel-Merle-d’Aubligné score. Radiological analysis searched for lucent lines and signs of wear. The actuarial survival was determined.

Results: One patient (1 hip) was lost to follow-up. Thirteen patients (14 hips) died of intercurrent causes. Six hips required revision for aseptic loosening (isolated cup loosening in five and bipolar loosening in one) at 8.5 years on average (4.5–12). There were 22 intraoperative complications (27%) including 18 fractures or femoral stem misalignments and four cases of damage to the acetabular fundus. Other complications included one postoperative dislocation, two sciatic nerve palsies with partial recovery, and one non-union of the greater trochanter. There were no infections. At maximum follow-up (11.8±4.7 years, ragne 5.4–20), the mean functional score was 16.5 (15–18) versus 9.9 (6–14) preoperatively (p< 0.05). There were no femoral lucent lines. A complete lucent line around the cup was observed in eleven hips including six with a massive cemented alumina cup. Considering revision for aseptic loosening as failure, cumulative survival at 12 years was 82% (95%IC 67–96%) for the cup and 98% (92–99.7%) for the femoral stem.

Discussion: These results confirm the high risk of intraoperative complications of total hip arthroplasty performed for failure of femoral osteotomy. Architectural changes expose these patients to technical problems. The survival of the implants appears to be relatively unaffected by the prior procedure but the functional results are slightly less satisfactory then for primary arthroplasties.

Purpose: The aim of this study was to evaluate quality-of-life (QoL) in patients undergoing bilateral hip arthroplasty implanted during the same operation.

Material and methods: Sixty-one patients (28 women and 33 men) underwent surgery between November 1989 and February 2002. Average age was 42±14 years (13–76). Indications were primary osteoarthritis (n=24), secondary osteoarthritis (n=31), aseptic osteonecrosis (n=25) and rheumatoid disease (n=6). The implants (Ceraver Osteal) were cemented (50 stems, 11 cups) or coated with hydroxyapatite (72 stems, 11 cups). An alumina-alumina bearing was used in all cases. The Postel-Merle-d’Aubigné score was noted to assess function. QoL was measured prospectively in 27 patients using the SF-36 and the WOMAC, preoperatively and every three months.

Results: None of the patients were lost to follow-up. Complications included two intraoperative femoral fractures treated by cerclage, one early dislocation, three thromboemoblic events (including one case of pulmonary embolism). Unipolar revision was required for one hip due to aseptic acetabular loosening at 6.5 years. Surgical cleansing was performed in one other hip for infection. Intraoperative blood loss was 1529±451 ml (540–2550). Mean hospital stay was 13±2.5 days (8–22). At mean follow-up of 49±33 months (12–162), the mean function score was 17.8±0.5 (16–18) versus 10±2.7 (3–14) preoperatively (p< 0.05). Clinical outcome was good or excellent in 98% of the hips. There were no radiological signs of wear. A complete lucent line developed around one cup. The quality of life scores improved significantly (p< 0.01) as soon as three months postoperatively for the items ‘social activity’, ‘physical activity’ and ‘pain’, particularly in men p< 0.05).

Discussion: Bilateral hip arthroplasty during the same operative time is not advocated by all authors. It is a difficult surgical situation requiring rigor and skill. The drawbacks include longer operative time, greater blood loss, and in some patients, higher morbidity. This approach however enables treating bilateral disease in one operation, particularly in younger subjects. Use of an alumina-alumina bearing and non-cemented implants is particularly indicated. The results of this series validate the efficacy of this technique which allows rapid improvement in the patients’ quality-of-life.

Purpose: Surgical techniques must be evaluated before proceeding with widespread use. The evaluation system is usually copied after that used for drugs, relying on randomised trials. This system fails however to assess one dimension, i.e. quality control. The purpose of the present study was to demonstrate the usefulness of an evaluation technique taking into account the capacity to control the quality of a surgical procedure and determine the reliability, reproducibility, and controllability of the technique. This method of evaluation was applied to computer-assisted surgery for total knee arthroplasty.

Material and methods: Computer-assisted surgery based on 3D bone reconstruction was used for 78 knees. The main outcome assessment criterion was the mechanical axis from the centre of the femoral head to the centre of the ankle. The desired alignment was between 3° varus and 3° valgus. Alignments were measured continuously by an independent operator. A Cusum curve was drawn over time and tested after each operation to determine whether the procedure under evaluation could be continued. The same method was applied to the position of the individual femoral and tibial implants setting the limits at two degrees around the perpendicular mechanical axis (AP view).

Results: The mechanical axis was between 3° varus and 3° valgus in 91% of the knees. The continuous evaluation curve showed that the procedure was under control throughout the trial. There was a learning curve that plateaued at 27 knees. Evaluation of the position of the individual implants showed a trend towards femur valgus over time which was compensated by a trend towards tibial varus.

Discussion: Industrial quality control procedures are well established and widely used. The goal of this work was to apply the same quality control methodology to a surgical procedure. Before undertaking a randomised trial this type of evaluation can affirm that the procedure is well controlled and that using an innovating technique under these conditions does not expose patients to undue risks.

Purpose: Classical instrument sets for implantation of total knee arthroplasty (TKA) can be perfected. Computer-assisted implantation appears to offer improved technical quality. The purpose of this study was to compare a matched series of TKA implanted with the conventional method and with a computer-assisted navigation system.

Material and methods: Seventy-eight prostheses implanted with a computer-assisted system based on 3D CT-scan reconstruction of the lower limb were matched with 78 prostheses implanted by a highly-trained operator. The knees were matched for gender, aetiology, surgical approach, and axial deviation. There were no significant differences between the groups for these variables. An intramedullary aiming device was used for knees undergoing the conventional procedure. Navitrack(r) was used for the computer-assisted implantations. The same prosthetic system (Wallaby) was used for both series. An independent operator assessed the double-foot stance gonometries. The femorotibial axis was measured as was the individual position of the tibial and femoral pieces.

Results: Axis was within 3° varus and 3° valgus for 92% of the knees operated on with the navigation system. This same range was found for 59% of the conventional procedures. The difference was significant (p< 0.0001). Analysis of the individual femoral and tibial components did not demonstrate any significant difference.

Discussion: Results of TKA are dependent in part on operative technique. The objective is generally achieved with the computer-assisted technique but is not with the conventional technique. Navigation could be useful to achieve successfully short-term objectives. Its contribution to mid-term outcome remains to be demonstrated.

Introduction: Previous in vivo kinematic analyses of the hip joint have determined that femoral head separation from the medial aspect of the acetabular component occurs in metal-on-polyethylene THA. The present study analyzes subjects having either an alumina-on-alumina (AOA),alumina-on-polyethylene (AOP),metal-on-metal (MOM) or metal-on-polyethylene (MOP) THA during gait to determine if the incidence of hip joint separation varies based on articular surface material.

Methods: Forty subjects were analyzed in vivo using video fluoroscopy. Ten subjects had a AOA THA, ten an AOP THA, ten a MOM THA, and ten having a MOP THA. All THA subjects were implanted by two surgeons and were judged clinically successful (Harris hip scores > 90.0). Each subject performed normal gait on a treadmill and an abduction/adduction leg lift maneuver while under fluoroscopic surveillance. The two-dimensional (2D) fluoroscopic videos were converted into 3D using a computer automated model-fitting technique. Each implant was analyzed at varying flexion angles to assess the incidence of hip joint separation.

Results: During gait and the abduction/adduction leg lift, no separation was observed in subjects having an AOA THA or in subjects having a MOM THA. Similar to our previous studies pertaining to subjects having a THA with a polyethylene acetabular insert, all ten subjects having a MOP THA and 6/10 subjects having an AOP THA experienced hip joint separation. The maximum amount of separation was 7.4 mm for a subject having an AOP THA and 3.1 mm for a subject having a MOP THA.

Discussion: This study shows femoral head separation from the medial aspect of the acetabular component can occur in the presence of a polyethylene liner. The femoral head often remains in contact with the liner, hinging superolaterally. Potential detrimental effects resulting from hip joint separation include premature polyethylene wear, component loosening (secondary to impulse loading conditions) and hip instability. Wear may be enhanced due to creation of multidirectional wear vectors or excessive loads due to eccentric femoral head pivoting. The absence of separation observed in AOA and MOM THA designs may be related to increased wettability of these materials and tighter radial tolerances resulting in a cohesive lubrication film. This data may be of value in hip simulation studies to better duplicate wear patterns observed in retrieval analyses and assist in the understanding of the lubrication regime and wear rates in AOA and MOM designs, allowing for the synthesis of prosthetic components that minimize wear and optimize kinematics.

From 1979 to 2002, 131 total hip replacement were performed consecutively in patients less than 30 years of age (13 to 30,7 mean 24;2) in 75 patients (44 in males and 31 in females. Seventy six in 57 patients could have more than 2 years follow-up and will presented hereby. Regarding the type of prosthesis, 59 stem were cemented and 16 cementless. Five different socket were implanted: 6 screw-in metal back: 8 bulky cemented, 23 bulky cementless, 13 metalback press fit with titanium mesh and 26 HA covered.

Underlying diseases were Avascular necrosis in 46, 8 inflammatory disease, 6 after infected articulation, epiphysiolysis in 4 and acetabular fracture in 3.

48 were done primarily, 28 were a revision procedure and 10 had some past history of infection.

Mean follow up was 7,84 years (range 1,13-22,9). One patient (two hips deceased at 1,1 year. One hips was lost to follow-up. 73 had complete clinical and radiological evaluation.

Nine hips were revised from 2,97-18,64 years after the index procedure (mean 8,53). In 7 only the socket was revised, in two both components. Two of these were infected (secondary infection in one). Of the remaining: 45 had no pain, 18 slight uncommon pain, 10 were classified 5 and 8 had some limp.

Radiological evaluation: 56 had no lucent lines nor subsidence, 4 had some radiolucent line none progressive and 1 had a complete lucent line: and is considered as impending failure. In no case osteosysis was documented.

With the exception of socket loosening due to non optimal design of the initial system (bulky alumina cemented or cementless) the overall results are in favor of theis material in young and active patients.

Aim: The aim of the study was to analyze the results of hybrid alumina prothesis using a pressþt metal backed socket and a cemented stem in young and active patients. Methods: From 1990 to 1992, 71 hybrid alumina-onalumina hip replacements were performed in 62 consecutive patients under age 55, with a mean age of 46 years at surgery. There were 56 primary procedures and 15 revision procedures. The prostheses included a cemented Ti alloy stem, a 32-mm alumina head, and a press-þt metal backed socket with an alumina insert. Results: 3 patients (4 hips) died from unrelated causes. 4 hips had revision surgery for deep infection, unexplained persistant pain, fracture of alumina head, and socket aseptic loosening. The 9-year survival rate was 93.7% if revision for any cause was the end point, and 98.4% if revision for aseptic loosening was the end point. Results in surviving patients with a minimal 5-year followup and an average followup of 8 years (57 hips) were excellent in 47 hips (82.5%), very good in 8 hips (14%), good in 1 hip and fair in one hip. 38% of the sockets had a thin and partial lucent line and 1 socket had a complete lucency less than 1mm thick. One stem had isolated femoral osteolysis. There was no detectable component migration nor acetabular osteolysis. Conclusion: Hybrid alumina prosthesis gave satisfactory results at mid term in active patients. Press-þt metal backed socket appeared as a reliable method of acetabular þxation in alumina-alumina hip replacement. Excellent results of cemented stem þxation may be related to low wear debris production.

Between 1990 and 1992, we implanted 71 hybrid alumina-on-alumina hip arthroplasties in 62 consecutive patients under the age of 55 years, with a mean age of 46 years at surgery. There were 56 primary and 15 secondary procedures. The prostheses involved a cemented titanium alloy stem, a 32 mm alumina head, and a press-fit metal-backed socket with an alumina insert. Three patients (four hips) died from unrelated causes. Four hips had revision surgery for either deep infection, unexplained persistent pain, fracture of the alumina head, or aseptic loosening of the socket. The nine-year survival rate was 93.7% with revision for any cause as the end-point and 98.4% with revision for aseptic loosening as the end-point.

The outcome in the surviving patients (50 patients, 57 hips) with a minimum five-year follow-up (mean eight years) was excellent in 47 hips (82.5%), very good in eight (14%), good in one and fair in one. A thin, partial, lucent line, mainly in zone III was present in 38% of the sockets and one socket had a complete lucency less than 1 mm thick. One stem had isolated femoral osteolysis. There was no detectable component migration nor acetabular osteolysis.

This hybrid arthroplasty gave satisfactory medium-term results in active patients. The press-fit metal-backed socket appeared to have reliable fixation in alumina-on-alumina hip arthroplasty. The excellent results using cemented fixation of the stem may be related to the low production of wear debris.

Purpose: Filling bone loss during revision total hip arthroplasty raises many problems related both to the surgical technique and to the type of bone substitute used. The purpose of this study was to report the clinical and radiographic results obtained in a series of femur reconstructions using impacted calcium phosphate ceramics.

Material and methods: The technique used here was derived from the method developed for impacted fragmentary grafts by Ling and Gie. Grains of macroporous biphasic calcium phosphate ceramic (MBCP) were impacted into the femoral shaft to obtain a stable sheath into which the stem could be cemented (Ceraver Osteal). This technique was used from March 1996 to october 2000 in 18 patients (20 hips) undergoing revision for femoral loosening in 11 (including septic loosening in eight), femoral osteolysis (one hip), pain (one hip), and instability (one hip). Mean age ate revision was 66 years (range 30–79). Most of the femoral bone defects were classed grade IV. The grains of MBCP were used alone in 13 cases, in a mixture with allografts in five cases, and in a mixture with autologous bone in two cases.

Results: Mean follow-up was 31 months (range 8–70). None of the patients were lost to follow-up. There were two intraoperative femur shaft fractures which healed without sequela. Two patients required a second revision for loosening (including one septic) 20 and 16 months after the first revision. At last follow-up, the mean PMA score had improved to 16 (12–18) (p< 0.05) and 67% of the patients achieved a good or excellent clinical result. Radiologically, there were 14 cases of good osteointegration of the MBCP grains without implant migration. Mean shortening was 3 mm (3–5) was observed in three cases and a stable incomplete lucent line was observed in one patient with no clinical impact.

Discussion: Calcium phosphate ceramic material can be useful to overcome the problem of major bone loss in RTHA. It provides an attractive alternative to the disadvantages of bone grafting and helps, in theory, improve primary implant stability. The original technique presented here has allowed us to achieve promising short-term results in young patients with an adequate femur.

Purpose: Tissue engineering offers new therapeutic perspectives with the possibility of producing cartilage tissue for a large number of patients. These structures are composed of an absorbable synthetic support and competent cells. Two types of cells can be proposed: articular chondrocytes harvested from the peripheral part of the joint, or mesenchymatous stem cells (MSC) present in the bone marrow and possessing chondrogenic potential. The purpose of this study was to determine the optimal cell source and the best supporting material for in vitro production of cartilage.

Material and methods: Isolated rabbit MSC were harvested and amplified with cell culture for 21 days. After this period, 20–40 million cells/ml were combined with polyglycolic acid sponges (3 types of sponges 1x1x0.2 cm2) and cultured in TGFß-enriched medium under specific dynamic conditions allowing gas exchange. The tissue obtained was compared with structures of identical size obtained with differentiated chondrocytes harvested from the same animals. The study included a histological analysis and immunohistochemistry for type I, II, and X collagen and biochemistry for DNA content, glycosaminoglycanes (GAG) and type II collagen.

Results: After 3 weeks in culture, the composites obtained with MSC preserved their size and had the white pearly aspect of hyalin cartilage. The histological analysis and immunohistochemistry tests for type II collagen confirmed the presence of a cartilaginous matrix throughout the thickness of the fragments. The GAG and type II collagen contents were significantly higher with MSC compared with chondrocytes, irrespective of the supporting material.

Discussion: This study demonstrated that cartilaginous tissue fragments can be obtained with MSC cultured on PGA supporting material under very specific conditions. Use of these cells offers the advantage of easy harvesting followed by in vitro amplification, and thus less harvesting morbidity. Complementary studies are needed to evaluate the behaviour of these living materials after implantation in the articulation.

Purpose: During revision of alumina-on-alumina prostheses, reimplantation of a ceramic head on the former stem raises the risk of head fracture. Furthermore, serious deformation of the metal head has been reported after failure of ceramic-on-ceramic prostheses. The purpose of this retrospective study was to evaluate the incidence of these complications and analyse clinical and radiological results of revision for alumina-on-alumina total hip arthroplasties.

Material and methods: This consectutive series included 107 patients (74 women and 33 men, mean age 65 years, age range 32–91 years) who underwent 118 revision arthroplasties from 1976 to 1997. The cause in the majority of the cases was isolated non-infected cup loosening (80%) or ceramic implant fracture (4%). There were 72 cemented alumina cups, 38 screwed cups, six press-fit metal-backed cups, and two massive alumina impacted cups. Cavitary acetabular osteolysis was present in 67% of the cases. The cup was replaced alone in 94 cases (80%). The implanted cup was a polyethylene cup in 93 cases and an alumina cup in 25. When the femoral stem was left in place, a new ceramic head was implanted in 49 cases (39 alumina, 10 zircone). The alumina head was replaced by a metal head in 18 cases.

Results: Four early dislocations and two infections were noted. Mean follow-up after revision surgery was 67 months. Fourteen patients were lost to follow-up. Sixteen patients required revision surgery, ten of them for repeated cup loosening. At last follow-up (mean 61 months), there were no failures among the 49 ceramic heads implanted on a stem left in place. No revisions were required for polyethylene cup wear or metal head wear. In all, 72 hips were evaluated at a minimum two years follow-up. The functional score at last follow-up was 15.2±3.5. Seven-year actuarial survival was 95.5% taking revision of non-infected revision as the endpoint.

Discussion and conclusion: Analysis of the results shows that acetabular loosening is the main cause of revision of alumina-on-alumina total hip arthroplasties. The femoral stem was loosened in only nine cases and could be preserved in 80% of the cases. Replacement of an alumina-on-alumina couple with a metal-on-polyethylene couple does not appear to be a contraindication in this series.

Purpose: The purpose of this work was to analyse different techniques and outcome of total hip arthroplasty for acetabular degeneration after orthopaedically or surgically treated fracture of the acetabulum.

Material and methods: This retrospective analysis of a consecutive series was conducted by an independent observer. Sixty-four arthroplasties in 63 patients performed between 1979 and 2000 were included. Twenty-eight acetabular fractures had been treated surgically and 36 orthopaedically. Five types of cups were implanted (25 cerafit, 3 cerapress, 17 cemented alumina, 11 screwed, 7 polyethylene). All patients were assessed preoperatively and at last follow-up with the Merle d’Aubigné clinical scale. The postoperative and last follow-up radiograms were assessed according to Charnley and De Lee. Operative difficulties were assessed in terms of operative time, blood loss, and analysis of the operation reports. Actuarial survival was calculated.

Results: Mean follow-up was five years two months. Six patients were lost to follow-up early. Clinical outcome was satisfactory with significant improvement in the Merle d’Aubigné score. The 10-year survival rate was 81% taking aseptic loosening as the endpoint and 74% taking surgical revision as the endpoint. Operative time and blood loss were significantly related to loss of ace-tabular bone stock and to operator experience (p < 0.05). Survival was significantly related to acetabular bone defect (p < 0.05). There was no difference between the treatment modes used for the initial acetabular fracture for peroperative difficulty or survival.

Discussion: Total hip arthroplasty for acetabular degeneration secondary to acetabular fracture has given good functional results. Long-term survival is below that for primary arthroplasty, the only unfavourable factor identified being loss of acetabular bone stock. The surgical procedure is more difficult and requires a certain experience. We did not find any difference related to the type of treatment (orthopaedic or surgical) used for the initial acetabular fracture. It was difficult to interpret the influence of cup type due to the wide range of cups used in this series.

Controversy exists with regard to the thickness of cement mantles that are necessary around the femoral components of cemented total hip arthroplasties. Conventional teaching, based on bench-top or computor models and theoretical analyses, as well as post-mortem & follow-up studies, suggests that the cement mantle should be complete and not less than 2–3mm in thickness. Mantles that are less than this are held to be at risk from mechanical failure in the long term; if they are incomplete, focal lysis may occur and progress to aseptic loosening.

However, long term experience with a number of French cemented femoral components suggests that these conventions may be erroneous. These French femoral components include the Charnley-Kerboull (stainless steel) and the Ceraver Osteal (Ti6Al4V) stems, in both of which the underlying design principle is that the stem should completely fill the femoral canal, the cement then being used purely to fill the gaps. Such a design philosophy implies that the cement mantles will be very thin, and since both of these stems are straight and the femoral medullary canal is not, the mantles may not only be thin, but also in places incomplete.

Conventional teaching would suggest that any stem utilising mantles of this type would fail from a combination of focal lysis and cement fracture. Yet the long term results of both of these stems have been outstandingly good, with extremely low levels of aseptic loosening and endosteal lysis, irrespective of the bearing combinations being used. Both these stems have a surface finish of Ra < 0.1 microns. A third French design, the Fare stem, manufactured from Ti6Al4V and based on the same principles, was associated with bad results when manufactured with a rough (> 1.5 microns) surface, and appreciably better results after the surface roughness was changed to < 0.1 microns.

These findings, that constitute the ‘French Paradox’, have profound implications for the mechanical behaviour of cement in the femur and for the mechanisms that underlie stem failure from loosening.

In order to avoid the consequences of polyethylene wear in a high-risk population, 128 alumina-alumina total hip arthroplasty were implanted in 116 consecutive patients of 40 years old or less. Osteonecrosis and sequellae of congenital hip dislocation were the main etiologies representing 71% of the hips. The same titanium alloy cemented stem was implanted in all hips. Four alumina acetabular component fixations were used: cemented plain alumina socket (41 hips), screw-in ring with an alumina insert (22 hips), a press-fit plain alumina socket (32 hips) and a press-fit titanium metal back with an alumina insert (33 hips).

Eight patients (11 hips) died during the follow-up period. Sixteen revisions were documented, 12 for ace-tabular aseptic loosening, 3 for bipolar loosening (2 were septic), and 1 for unexplained pain. Eighty-nine hips were followed radiologically for two to twenty years. No femoral nor acetabular osteolysis were observed with an average follow-up of 8.4 years. Wear was unmeasurable. Four additional sockets showed definite migration. The respective survival rate at 7 years were 91.4% for the cemented cup, 88.8% for the screw-in ring, 95.1% for cementless press-fit plain alumina socket and 94.3% for the metal-back press-fit component.

The ten-year survival rate was 88.0% for the cemented socket and 88.8% for the screw-in ring. The fifteen-year survival rate was 76.7% for the cemented socket. The occurrence of a graft was the only prognostic factor with a 62.6% survival rate at ten years for the grafted hips and a 90.1% for the non-grafted hips (p=0.004).

The alumina-alumina bearing surfaces for young patients appeared as a valuable alternative to standard metal-polyethylene system. There is a need to improve socket fixation if we want to have a survival of the arthroplasty as long as the life expectancy of this increasing and demanding population. The last design with a fully coated HA titanium shell and an alumina liner seems to fulfill the requirements.

Introduction: Complex fracture of the acetabulum are difficult to treat. If an osteosynthesis is performed difficult surgery resulted in blood loss, long operating time, high risk of sepsis and failure. Even if the fracture is well operated and ideally stabilised there is a major risk of secondary osteoarthrosis. This can be related to bone necrosis , cartilage surface damage , bone loss.

There are also intraoperative risks of neural damage: sciatic nerve as well as gluteus medius nerve. On the other hand , modern surgical technique including an alumina against alumina bearing could allow very long term survival without any activity limitation and this even in very young patients.

Secondary procedure after a failed osteosynthesis provides statistically worse functional results than primary total hip. The surgery is more difficult because of hardware retrieval, nerve dissection, bone reconstruction and remaining muscular dysfunction.

Materials and Methods: To address these issues we reviewed our results of total hip for acetabular fractures. 80 patients received a total hip for acetabular fracture. From 1980 to 1998: 58 acetabular fractures in 57 patients sustained a total hip: 39 males and 18 females. Mean age: 50 years (from 21 to 80). 35 had had a conservative treatment, 22 had had an osteosynthesis. Delay between fracture and total hip: operated: 10 years, non-operated: 6 years. All prosthesis had an alumina against alumina couple. The stem was always made of titanium alloy, it was smooth, collared and cemented. The socket was plain alumina cemented 8, cement less : 3, metal back alumlina insert: 29, screw in cup with alumina liner: 10, plain polyethylene cemented: 8.

Results: Follow-up: from 6 months to 20 years (mean 5,5years). Last Postel Merle d’Aubigne rating: 16,1(8–18) 9 revisions : 1 bipolar aseptic loosening, 8 socket loosening : 2 septic , 6 aseptic. (2 screws in , 6 cemented).

There were 22 neural disorder; 19 sciatic palsies; 13 post trauma; 4 post osteosynthesis; 2 post THR; 3 gluteus medius palsy. 7 sepsis: 4 post osteosynthesis, 3 post THR (including 2 post osteosynthesis).

Discussion: The results presented were inferior to a regular total hip if an osteosynthesis have been performed previously. Reasons for these inferior results were limp due to previous palsy of gluteus medius nerve, sciatic sequellae, complications of previous sepsis and so on. In contrast cases who had at first orthopaedic treatment followed some weeks later by a total hip experienced very good results. It is difficult to conclude from this limited series. But we are actually on the way to modify our perspectives.

Many weak results could have been avoided by doing fine primary surgery. We could expect better functional results with less complications regarding sepsis, nerve damage, muscle preservation if we perform a primary total hip in conjunctions with acetabular reconstruction. Osteosynthesis is still recommended for simple acetabular fracture with large displacement involvement of the posterior wall or one column not comminuted.

Purpose: The purpose of this retrospective study was to assess long-term clinical and radiological outcome in a continuous series of alumine-alumine total hip arthroplasties.

Material and methods: This series included 118 total hip arthroplasties performed in 106 patients (70 men and 36 women), mean age 62.2 ± 11.9 years (32–89). Primary degenerative hip disease was the main aetiology. All the arthroplasties were performed by the same operator. In all cases, the femoral piece was a titanium alloy with a Morse cone for fixation of the femoral head; an “all alumine” cup was used for all. The implants were fixed with cement for 85 hips, without cemented for 29, and with a hybrid technique for four. The Merle d’Aubigné score was used to assess clinical outcome. Classical landmarks on the AP pelvis views were used to assess implant migration. Cup wear was measured using the Livermore method. Actuarial survival curves were plotted.

Results: At mean follow-up of 20 years, 45 patients (51 hips) were still living and had not required revision. Twenty-five patients (25 hips) had undergone revision for replacement of the acetabular component and/or the femoral component. Twenty-seven patients (30 hips) had died and nine patients (12 hips) were lost to follow-up. The mean functional score was 16.2 ± 1.8 at last follow-up. Cumulated survival at 20 years was 85.6% (95%CI 72.2–99.0) for cups without cement compared with 61.2% (95%CI 46.8–75.6) for stems without cement (log rank test p = 0.0162). Cumulated survival at 20 years was 84.9% (95%CI 71.1–98.8) for stems without cement compared with 87.3% (95%CI 77.4–97.1) for cemented stems (log rank, p < 0.05). Wear was unmeasurable. Osteolytic lesions required reconstruction with an allograft in three of the 25 revisions. There were no cases with fracture of the alumine head or cup.

Discussion: The limited number of cases with osteolysis at 20 years is probably related to minimal wear of the prosthetic components. Fixation of alumine cups could still be improved.

Severe acetabular fractures are difficult to treat. Complications include blood loss, neural damage, long operating times, and a high risk of sepsis and failure. Even when the fracture is ideally stabilised, there is a major risk of secondary osteoarthritis. This can be related to bone necrosis, cartilage surface damage, bone loss.

However, even in young patients modern surgical techniques, including use of an alumina-against-alumina bearing, may facilitate long-term survival without limitation of activity.

Functionally, the results of secondary procedures after failed osteosynthesis are statistically worse than after primary total hip arthroplasty (THA). The surgery is difficult because of material retrieval difficulties, nerve dissection, bone reconstruction and remaining muscular dysfunction.

We reviewed the results of 80 THA procedures done between 1980 and 1998 to treat 58 acetabular fractures. The mean age of our 57 patients (39 men and 18 women) was 50 years (21 to 80). The mean delay between fracture and THA was 10 years in 22 patients who had undergone osteosynthesis and six years in 35 patients who had been treated conservatively. The mean follow-up period was 5,5 years (6 months to 20 years).

There were eight instances of socket loosening, two of which were septic and six aseptic. Two of these patients had screw-in prostheses and six had cemented. There were 19 sciatic palsies, 13 of which developed after trauma, four after osteosynthesis and two after THA. There were three cases of gluteus medius palsy. In two of four cases of sepsis that occurred after osteosynthesis, sepsis recurred after THA, and in one patient sepsis developed after THA.

In this limited series, patients who underwent THA after osteosynthesis did not have as good an outcome as those in whom initial orthopaedic treatment was followed some weeks later by THA. We believe many poor results could have been avoided with better primary surgery. Functional results are likely to be better, and the incidence of complications lower, if primary THA is performed in conjunction with acetabular reconstruction. Of course, for treatment of simple acetabular fracture involving major displacement of the posterior wall, one column osteosynthesis is still recommended.

Alumina-on-alumina bearings in total hip arthroplasty (THA) were introduced about 30 years ago. Theoretically, their excellent tribological properties and low debris generation provide a solution to osteolysis. The 24-year experience of the Paris group suggests that osteolysis is no longer a problem. Any need for revision was related to mechanical failure rather than to debris, except in a few cases in which a pros-thesis that had been loose for many years resulting in metal-on-ceramic impingement.

Cemented socket and screw-in ring metal-backed alumina yielded poor results. The recent improvements in alumina quality and in ceramic fixation, using cementless fully coated hydroxyapatite material, may provide a solution in active young patients. Preliminary results of the first 100 THA procedures using a cementless stem and socket and 32-mm alumina head, and alumina liner secured with a Morse taper, are very encouraging. One socket required revision because of poor initial surgery in a severe acetabular fracture. Patients ranged in age from 14 to 71 years (median 45 years).

We have carried out a prospective, randomised study designed to compare the long-term stability of the stem of cementless femoral implants with differing surface configurations. A total of 50 hips (46 patients) was randomised into two groups, according to whether the medullary stem had been grit blasted (GB) or coated with hydroxyapatite (HA). Both femoral prostheses were of the same geometrical design. We used Ein Bild Roentgen Analyse femoral component analysis (EBRA-FCA) to assess the stability of the stem. The mean follow-up was for 8.66 years.

The mean migration of the stem was 1.26 mm in the HA group compared with 2.57 mm in the GB group (Mann-Whitney U test, p = 0.04). A mixed model ANOVA showed that the development of subsidence was statistically different in the two groups during the first 24 months. After this subsidence increased in both groups with no difference between them. Our results indicate that, with the same design of stem, HA coating enhanced the stability of the femoral stem when compared with GB stems.

We compared and quantified the modes of failure and patterns of wear of 11 Mittelmeier and 11 Ceraver-Ostal retrieved alumina-alumina hip prostheses with reference to the corresponding clinical and radiological histories.

Macroscopic wear was assessed using a three-dimensional co-ordinate measuring machine. Talysurf contacting profilometry was used to measure surface roughness on a microscopic scale and SEM to determine mechanisms of wear at the submicron level.

The components were classified into one of three categories of wear: low (no visible/measurable wear), stripe (elliptical wear stripe on the heads and larger worn areas on the cups) and severe (macroscopic wear, large volumes of material lost). Overall, the volumetric wear of the alumina-alumina prostheses was substantially less than the widely used metal and ceramic-on-polyethylene combinations. By identifying and eliminating the factors which accelerate wear, it is expected that the lifetime of these devices can be further increased.

Limited success in regenerating large bone defects has been achieved by bridging them with osteoconductive materials. These substitutes lack the osteogenic and osteoinductive properties of bone autograft. A direct approach would be to stimulate osteogenesis in these biomaterials by the addition of fresh bone-marrow cells (BMC).

We therefore created osteoperiosteal gaps 2 cm wide in the ulna of adult rabbits and either bridged them with coral alone (CC), coral supplemented with BMC, or left them empty. Coral was chosen as a scaffold because of its good biocompatibility and resorbability. In osteoperiosteal gaps bridged with coral only, the coral was invaded chiefly by fibrous tissue. It was insufficient to produce union after two months. In defects filled with coral and BMC an increase in osteogenesis was observed and the bone surface area was significantly higher compared with defects filled with coral alone. Bony union occurred in six out of six defects filled with coral and BMC after two months. An increase in the resorption of coral was also observed, suggesting that resorbing cells or their progenitors were present in bone marrow and survived the grafting procedure. Our findings have shown that supplementation of coral with BMC increased both the resorption of material and osteogenesis in defects of a clinical significance.

We made a semiquantitative study of the comparative histology of pseudomembranes from 12 loose cemented ceramic-ceramic and 18 metal-polyethylene total hip replacements. We found no significant difference in cellular reaction between the two groups, but there was a major difference in the origin of the particulate debris. In the metal-polyethylene group, polyethylene of articular origin was predominant, while in the ceramic-ceramic group the cellular reaction appeared to be a response to zirconia ceramic particles used to opacify cement used for fixation.

Isolation and characterisation of the debris showed that the zirconia particles formed the greatest proportion (76%) in ceramic-ceramic hips, while alumina debris of articular origin formed only 12%.

Our study has indicated that aseptic loosening of ceramic cups is not due to a response to debris generated at the articular interface, but to mechanical factors which lead to fragmentation of the cement.