Treatment of aseptic osteonecrosis of the femoral head: Historical aspects.

The treatment of aseptic osteonecrosis (ON) of the femoral head has been the subject of numerous therapeutic and surgical proposals due to the absence of medical treatment with proven efficacy. For many years, the goal of surgical treatment was to avoid total hip replacement (THR) with uncertain survival in patients considered too young (30-50 years) for this procedure. Numerous conservative treatments were thus proposed: core decompression with numerous variants, non-vascularized and vascularized bone grafts, intertrochanteric and rotational transtrochanteric osteotomies, cementing. The lack of a common classification and a lack of knowledge of natural history complicated the interpretation of the results for a long time. Nevertheless, it appeared that these treatments were effective only in the very early stages and among these in the limited ONs, medial rather than central and especially lateral, with discrepancies according to etiologies apart from sickle cell disease recognized by all as being pejorative. For the same reason, partial arthroplasties have been attempted and abandoned in turn: femoral head total and partial resurfacing and femoral prosthesis. The most recent advances are stem-cell-enhanced core decompression and progress in total arthroplasty, whose reliability has made it possible to extend the indications to increasingly younger patients seeking treatment with guaranteed or near-guaranteed efficacy. Most of the other interventions have disappeared or almost disappeared because of their lack of effectiveness especially in extensive and post-fracture ONs, sometimes because of their complexity and the length of their post-operative management, and also because they complicate and penalize a future total arthroplasty. This argues for early detection of ON at an early stage where the "head can be saved" by stem cell augmented core decompression, a minimally invasive treatment that leaves the chances of success of a THR intact.

High rate of fracture in the cementless modular Extrême™ (Mark I) femoral prosthesis in revision total hip arthroplasty: 33 cases at more than 5 years' follow-up.

INTRODUCTION: The modular concept has been recommended in femoral revision surgery with extensive bone loss, but entails mechanical complications: disassembly and fracture. The present retrospective study assessed the Mark I Extrême™ modular prosthesis at a minimum 5 years' follow-up. HYPOTHESIS: A cementless modular femoral stem facilitates revision in case of extensive bone loss, providing satisfactory results without risk of junction failure. MATERIALS AND METHODS: Thirty-three prostheses presenting aseptic loosening, including 3 with periprosthetic fracture, in 23 female and 9 male patients, with a mean age of 65 years (range, 49-83 years), were reviewed at a mean 6.3 years' follow-up (range, 5-9 years). Bone loss was assessed on the SOFCOT (17/33 grade 3 or 4) and Paprosky classifications (19/33 grade III or IV). One patient died; another was lost to follow-up, leaving 31 hips for analysis. Clinical assessment comprised Postel Merle d'Aubigné (PMA) and Harris Hip scores (HHS); radiological assessment used the Engh score and corticomedullary index (CMI). RESULTS: There were 15 complications requiring surgery: 9 (27%) unrelated to the implant (1 hematoma, 2 infections, 2 dislocations, 1 femoral non-union, 3 asymptomatic trochanteric non unions) and 6 (18%) implant-related (four 3-level fractures and 2 epiphyseal-metaphyseal disassemblies, requiring 3 total exchanges and 3 proximal component replacements). PMA and HHS scores showed significant improvement, PMA rising from 10.4 (6-18) to 14.4 (11-18) and HHS from 50 (19-88) to 80.9 (52-100). Bone regrowth was "certain" on the Engh classification in 11 cases (44%). There was no diaphyseal component subsidence, even in case of fracture or dissociation. CMI at the 3 junctions between the 4 quarters of the stem showed no significant change: 32.9 and 32.7, 41.2 and 38.7, and 41.6 and 39.9 respectively. Six-year survivorship was 81% (95% CI: 68-94%). DISCUSSION: In other series for the same type of implant, the rates of fracture (always metaphyseal-diaphyseal) were much lower: 0.8-3.8%. This stem ensures diaphyseal fixation in case of extensive bone loss, but incurs excessive risk of disassembly and fracture.

The long-term results of press-fit cemented stems in total knee prostheses.

We evaluated the long-term fixation of 64 press-fit cemented stems of constrained total knee prostheses in 32 young patients with primary malignant bone tumours. Initial stable fixation, especially in rotation, was achieved by precise fit of the stem into the reamed endosteum, before cementation. Complementary fixation, especially in migration and rotation, was obtained by pressurised antibiotic-loaded cement. The mean age at operation was 33 years (13 to 61). No patient was lost to follow-up; 13 patients died and the 19 survivors were examined at a mean follow-up of 12.5 years (4 to 21). Standard revision press-fit cemented stems were used on the side of the joint which was not involved with tumour (26 tibial and six femoral), on this side there was no loosening or osteolysis and stem survival was 100%. On the reconstruction side, custom-made press-fit stems were used and the survival rate, with any cause for revision as an end point, was 88%, but 97% for loosening or osteolysis. This longevity is similar to that achieved at 20 years with the Charnley-Kerboull primary total hip replacement with press-fit cemented femoral components. We recommend this type of fixation when extensive reconstruction of the knee is required. It may also be suitable for older patients requiring revision of a total knee replacement or in difficult situations such as severe deformity and complex articular fractures.

Antibiotic cements in articular prostheses: current orthopaedic concepts.

The possibilities and limits of antibiotic cements (ACs) have been assessed by many researchers. ACs are now approved by many drug agencies, including the US Food and Drug Administration (approval in 2003), with widespread use in prophylaxis and curative treatments. Laboratory experiments have achieved satisfactory antibiotic delivery without impairing the mechanical properties of ACs. Implantation in large animals (e.g. sheep) showed an antibiotic concentration in the bone cortex four times the minimal inhibitory concentration (MIC) 6 months after implantation. Human pharmacokinetics during total hip replacement (THR) show antibiotic concentrations 20 times the MIC in drainage fluids. No toxic concentrations have been detected in blood or urine, and no allergies, toxic effects, mechanical failures or selection of resistant microorganisms have been observed. Antibioprophylaxis has been assessed in prospective studies in over 1600 cases. In data from the Scandinavian arthroplasty registers, with an exhaustive follow-up of more than 240000 THRs, infection rate was reduced by ca. 50% (0.9% compared with 1.9%). In prostheses with severe infection, use of AC increases the infection control rate from 86% to 93% when using two-stage prosthetic exchanges. In moderate infection, a similar infection control rate (86%) was achieved either by two-stage exchange without local antibiotic or by one-stage exchange with AC; however, one-stage exchange achieved better functional results at lower cost and with reduced pain and hospital stay. Therefore, AC prophylaxis is widely used in countries with prostheses registers (Northern Europe), and use of ACs as treatment for infected prostheses is often considered as the gold standard in the EU and North America. However, AC is only an adjuvant treatment, and excision of infected and devascularized tissues as well as systemic antibiotic treatment managed by a multidisciplinary team remain the main factors of infection control.

[Hip dysplasia and misalignment in patients aged 20-50 years]. / Dysplasie et conflits de hanche de 20 à 50 ans.

Anterior hip pain in young adult (20 to 50) has two main causes: secondary osteo-arthritis on development dysplasia of the hip, and femoro-acetabular impigement (FAI). This symposium had two parts: the first one analyses long-term results of non-prosthetic surgery (283 osteotomies and shelfs at 15 years FU). The second part concerned the different syndromes with acute anterior hip pain, especially due to FAI and to labral tears.In hip dysplasia, 56 shelf operations, 100 proximal femoral varus osteotomies associated or not with a shelf arthroplasty,and 127 Chiari osteotomies were examined with 10 years minimum follow-up. Only 15% of patients were lost at follow-up before 10 years and average follow-up was 15 years. Results were considered as satisfactory when the Merle d'Aubigne rating was 15/18 or more. The 3 main factors of good prognosis were: a complete correction of both femoral and acetabular dysplasia; age at operation under 40; a moderate arthritis (grade I or II according to De Mourgues and Patte). In single acetabular dysplasia with 3 favorable prognosis factors(no coxa valga, age under 40, arthritis 1 or 2), 85% good results were achieved at 15 years. When patients were over 40 at operation, or in arthritis grade over 2, only 55% of good results were observed. Varus osteotomies, associated or not with shelf arthroplasties, achieved also 85% goods results at 15 years when the 3 favorable prognosis factors were present. Similar good results were also obtained by Chiari osteotomy, but this operation was associated with 12% complications, and more that 25% of lasting limping. Therefore, with 85% good results at 15 years (and often over 20 years), non prosthetic surgery performed at 30-35 years, achieved better functional results than total hip arthroplasty, longer lasting, and not jeopardizing any further possibility of prosthetic surgery.As concerns acute anterior pain of the hip, the clinical and imaging patterns of the different syndromes have been precised: femoro-acetabular impigement by cam (or by pincer), labral tears in hip dysplasia. There were distinguished from the other secondary impigements, for example by acetabular malposition due to pelvis anteflexion or by other hip diseases: overuse arthritis, coxa retrorsa, etc. Several examples of typical syndromes were presented to support the recommended imaging techniques. The results of the speakers with different surgical treatments were reported as well as concerns open surgery than arthroscopic treatment (60 cases).

Long-term results of allograft composite total hip prostheses for tumors.

The functional results of standard reconstruction prostheses are impaired by instability because of poor muscular reinsertion, especially of the gluteal muscles. In 21 patients, composite hip prostheses including proximal femoral allografts were used after primary malignant tumor resection. Ten reconstructions used combined bone-tendon allografts that allowed reinsertion of the gluteal muscles to the allograft tendons. None of the 21 patients had dislocation or infection. Ten patients died within 2 years of surgery without complications requiring reoperations. The mean followup in the 11 other patients was 10 years. Eight patients had reoperation: four for loosening (two at 3 years, two at 11 and 12 years), and four had autologous graftings for nonunion of the trochanter or of the distal graft-bone interface. Evaluation of function in the 11 patients with follow-ups ranging from 4 to 15 years showed an average Musculoskeletal Tumor Society score of 77%. Satisfactory strength of the abductor muscles was achieved by reinsertion of the trochanter or by suture of the patients gluteal muscles with the combined tendon-bone allograft. At long-term, radiologically, the bony allograft showed no change in five patients, very mild resorption in five, and severe resorption in one. Stem fixation was excellent in 10 patients and fair in one. Comparison between the functional results of reconstruction prostheses versus composite prostheses showed a significant improvement with the composite prosthesis. In the authors' institution, at 10 years, the mechanical survival of composite prostheses was 81%, as compared with only 65% for reconstruction prostheses.

Trochanteric slide osteotomy in revision total hip arthroplasty for loosening.

We used a trochanteric slide osteotomy (TSO) in 94 consecutive revision total hip arthroplasties (90 with replacement of both the cup and stem). This technique proved to be adequate for removing the components, with few complications (two minor fractures), and for implanting acetabular allografts (18%) and reinforcement devices (23%). Trochanteric union was obtained in most patients (96%), even in those with septic loosening (18/19), major femoral osteolysis (32/32), or previous trochanteric osteotomy (17/18). TSO is versatile, since it can be extended by a femoral flap (four cases) or a distal femoral window (eight cases). Despite significant bone loss, in 24% of the femora and 57% of the acetabula, favourable midterm results were achieved and only six reoperations were required, Including two for trochanteric nonunion and two for loosening. It leaves the lateral femoral cortex intact so that a stem longer than 200 mm was needed in only 25% of patients. This is a considerable advantage compared with the extended trochanteric osteotomy in which the long lateral flap (12 to 14 cm) requires an average length of stem of 220 mm beyond the calcar. TSO provides an approach similar in size to the standard trochanteric osteotomy but with a rate of nonunion of 4% versus 15%. It reduces the risk of difficulties with removal of the stem, and removes the need for routine distal anchoring of long revision stems. The limited distal femoral compromise is very important in patients with a long life expectancy.

Characterisation and quantification of angiogenesis in beta-tricalcium phosphate implants by immunohistochemistry and transmission electron microscopy.

The aim of this study is the histological characterisation of angiogenesis in a macroporous biomaterial with quantification techniques used in oncology. Porous tricalcium phosphate implants were seated in the tibias of 12 rabbits. This work allows (1) morphological study with photonic microscopy, transmission electron microscopic and immunohistochemistry labelling for (2) quantification of vascularisation using anti-CD31 monoclonal antibody (3) quantification of proliferation using anti-PCNA polyclonal antibody (4) study of two angiogenic growth factors: VEGF and FGF-2. Quantification of angiogenesis revealed an outbreak kinetic with early vascular growth in first several days and a second growth phase after 4 weeks. This study reveals in macropores many isolated cells without adjacent vascular lumen, with endothelial phenotype. Expression of angiogenic growth factors reveals that all endothelial cells were VEGF-negative throughout the test period. FGF-2 expression by endothelial cells began 2 weeks post-implantation. Osteoblasts strongly expressed two markers throughout the test period. Furthermore, the procedure described here can be used to compare angiogenesis in different biomaterials or in the same biomaterial with the influence of macroporosities.

Volumetric analysis of osteonecrosis of the femur. Anatomical correlation using MRI.

We tested the accuracy of MRI for the precise quantification of the volume of osteonecrosis in 30 hips (stage III). The values were compared with direct anatomical measurements of the femoral heads obtained after total hip replacement. When the area of osteonecrosis was determined visually, and manually outlined on each slice, the accuracy of the measurement of volume was satisfactory, and the mean absolute deviation between MRI and anatomical measurements was similar to that between two MRI data sets. For ten of the hips which were measured by MRI, both before and after collapse, the volume did not appear to change significantly. Our findings suggest that the volume of osteonecrosis can be determined with accuracy by MRI, both before and after collapse.

Long-term results of hemipelvis reconstruction with allografts.

Thirteen patients underwent pelvic reconstruction by massive allografts after resection of a malignant tumor (primary in 10 patients and metastatic in three patients). In 10 patients, the tumor involved the acetabulum and iliac wing and was reconstructed by a hemipelvic allograft; this was accompanied by a hip arthroplasty in nine of the patients. In three patients, a femoral metaphyseal tumor extending to the acetabulum was reconstructed by a total acetabular allograft and a composite proximal femoral allograft prosthesis. Two patients (20%) had a local recurrence, and one patient died of massive pulmonary embolism. Postoperative complications were one infection and two dislocations. At 3 years, one cup loosening and one acetabular fatigue fracture required surgery. The functional result was excellent in two patients whose gluteal muscles could be spared, good (allowing a normal family life) in six patients, fair in two patients, and poor in two patients. Seven patients had a Musculoskeletal Tumor Society rating greater than 60% of normal (the mean rating in 12 patients was 56.4%). No evidence of long-term deterioration was seen in the patients with the longest followups (7, 8, 10, and 14 years). Reconstruction of the hemipelvis with massive allografts and arthroplasty is a rewarding but demanding procedure and should be reserved for physically active patients who are in good general health and are expected to have a response to anticancer therapy. The procedure is particularly suitable for patients with primary tumors.

Bilateral hip osteonecrosis: influence of hip size on outcome.

OBJECTIVE: To measure the volume of osteonecrosis in 30 patients with disease in both hips (one side with collapse and the other without at Ficat stage I). METHOD: The volume of the osteonecrosis was measured by magnetic resonance imaging. RESULTS: The progression to collapse was influenced by the size of the lesion in each patient. The first collapsed hip was that with the largest volume of osteonecrosis. CONCLUSION: The volume of the osteonecrotic lesion on the second hip (stage I without collapse) is a good predictor of the time to collapse of this second hip.

Decrease in the mesenchymal stem-cell pool in the proximal femur in corticosteroid-induced osteonecrosis.

We have evaluated bone-marrow activity in the proximal femur of patients with corticosteroid-induced osteonecrosis and compared it with that of patients with osteonecrosis related to sickle-cell disease and with a control group without osteonecrosis. Bone marrow was obtained by puncture of the femoral head outside the area of necrosis and in the intertrochanteric region. The activity of stromal cells was assessed by culturing fibroblast colony-forming units (FCFUs). We found a decrease in the number of FCFUs outside the area of osteonecrosis in the upper end of the femur of patients with corticosteroid-induced osteonecrosis compared with the other groups. We suggest that glucocorticosteroids may also have an adverse effect on bone by decreasing the number of progenitors. The possible relevance of this finding to osteonecrosis is discussed.

[Tricalcium phosphate, an antibiotic carrier: a study focused on experimental osteomyelitis in rabbits]. / Phosphate tricalcique, vecteur d'antibiotiques: étude sur foyer d'ostéomyélite expérimentale chez le lapin.

PURPOSE OF THE STUDY: Macroporous beta tricalcium phosphate ceramic beads were elaborated to be a resorbable bone substitute and a drug delivery system carrying gentamicin or vancomycin. The aim of this study was to evaluate this implant into a rabbit experimental osteomyelitis. MATERIAL AND METHOD: Experimentation included 24 rabbits and was performed in three stages, according to Norden's description. Induction of osteomyelitis was obtained by injection of a sclerosing agent and of Staphylococcus aureus through the lateral side of the metaphysis of the proximal tibia. Three weeks after inoculation, animals were randomly dispatched to one of the three treatment groups. After surgical debridment (to collect cinetics data), the first group received no further treatment and was considered as a control; the second group received a ceramic implant; the third group received a gentamicin-loaded ceramic implant. Euthanasia occurred between 2 days and 21 days after the debridment. Bone samples were obtained to quantify the bacterial and gentamicin bone concentrations. Gentamicin level was also measured inside the ceramic implant. Antibiotic concentration was assessed by a immunoenzymatic method. RESULTS: Osteomyelitis was obtained in 21 of the 24 animals (87.5%). Antibiotic release was early and complete (before the third day) but gentamicin still remained in the bone for 10 days. Bacterial concentration suggested an antimicrobial activity of the implant, but not a full sterilisation of the osteomyelitis. CONCLUSION: Norden's experimental osteomyelitis model with rabbit was proposed to assess the therapeutic activity of systemic antibiotics, but not to evaluate biomaterials. Therefore we have shifted for experimental evaluation of biomaterials to a metaphyseal osteomyelitis in the sheep, the patterns of which are close from those of the human disease.

[Wear and loosening of prostheses]. / L'usure et le descellement des prothèses.

In 1996, the outcome of any total joint replacement is loosening, occurring usually about 20 years after implantation. Loosening is not a mechanical failure of the bone-implant junction but the consequence of the osteolysis of the periprosthetic bone. It is due to an inflammatory pannus, a tissue constituted by macrophages, which are activated by wear particules originated by the articulating surfaces. The authors showed that this osteolysis is close from that observed with other inflammatory diseases and that it can be obtained with wear particules of many biomaterials, the polyethylene (PE) being the most common in clinical conditions. Several trends in order to reduce polyethylene wear or to replace PE by other materials are presented. Future improvements of the duration of joint prostheses depend on laboratories including surgeons involved in basic research: they are a mandatory link between the engineer and the biologist who study the mechanical and the biological aspects of the wear and of the fixation of biomaterials.