[Total hip arthroplasty after hip arthrodesis performed for septic arthritis]. / Désarthrodèse-prothèse de hanche pour séquelle d'arthrite septique: apropos d'une série de 17 cas à 6 ans de recul.

PURPOSE OF THE STUDY: Revision total hip arthroplasty (THA) after hip arthrodesis is an uncommon and challenging operation. The task would appear to be even more difficult if the arthrodesis was performed because of septic arthritis due to the theoretical risk of recurrent infection. We report our fifteen-year experience. MATERIAL AND METHODS: This retrospective study concerned 17 procedures performed in 17 patients (11 women, 6 men) between 1988 and 2003 on 5 right and 12 left hips. All of the patients had arthrodesis for sepsis: eight subsequent to tuberculosis and nine subsequent to septic arthritis (Staphylococcus aureus). We examined the impact of the initial arthrodesis (surgical technique, position, leg length) on neighboring joints and indications for de-fusion. Mean age was 53 years (range 32-74) and on average, the patients had a fixed hip for 36 years (range 7-59). Mean follow-up was six years (range 11 months to 15 years). Revision surgery was performed via a posterolateral approach for 12 hips (nine trochanterotomies) and via an anterolateral approach for five hips for implantation of nine cemented implants, six press fit implants, and two hybrid implants (cemented cup and press fit stem). Clinical assessment at last follow-up noted pain, walking capacity and joint motion. Leg length discrepancy was measured and complications were noted. RESULTS: The position of the original arthrodesis was considered satisfactory (flexion 20 degrees , adduction 0-10 degrees , external rotation 0-20 degrees ) for eight hips; leg length discrepancy was 4 cm (2-8 cm). Neighboring joints involved concerned the lumbar spine in 15 patients, the ipsilateral knee in ten patients, the contralateral knee in eight and the contralateral hip in six. The decision to remove the arthrodesis was based on functional needs related to lumbar pain (n=6), the homolateral knee (n=10, limping and leg length discrepancy), or an operation on the ipsilateral knee. After surgery, 14 hips (83%) were free of pain with improvement of the lumbar pain and pain of the homolateral knee. Six patients walked without support but 16 still had a limp. Flexion was 78 degrees . Leg length discrepancy was 2.5 cm on average and seven patients had balanced limbs. The postoperative period was uneventful for 14 of 17 patients (one paresia of the common fibular nerve, one femoral phlebitis, one early infection). Six late complications were noted: nonunion of the greater trochanter (n=2), recurrent ankylosis (n=1) and loosening (n=3). DISCUSSION AND CONCLUSION: An earlier history of infection does not appear to be a contraindication for implantation of a total hip arthroplasty after hip arthrodesis. Despite the long recovery period and the modest gain in joint motion, 80% of patients were satisfied after having had a blocked hip for 36 years on average.

[Combination of methylmethacrylate (acrylic cement) and antibiotics. Bacteriologic and mechanical study]. / Association méthacrylate de méthyle (ciment acrylique) et antibiotiques. Etude bactériologique et mécanique.

The authors report the results of a study about the association of acrylic cement with antibiotics. Three cements have been tested: Simplex, CMW, Palacos, with 14 different antibiotics. A series of experiments has been carried out in three phases: a macroscopic study of the polymerisation of the mixture; in vitro bacteriological studies; and mechanical studies (trials of resistance to traction, flexion, shock measuring the modulus of elasticity and hardness). In vivo bacteriological testings have been carried out on 10 patients. It has come out from this study that the polymerisation of cement, usually does not destroy antibiotics which remain active and that the mechanical properties of cement are modified in sundry manners. All additions of tested antibiotics modifie mechanical properties by about 25 p. 100 but some additions seem to be preferable. Improvements must still be made and confirmed by this type of research.

[Cellular culture of osteoblasts and fibroblasts on porous calcium-phosphate bone substitutes]. / Culture cellulaire d'ostéoblastes et de fibroblastes sur substituts osseux poreux en phosphate de calcium.

PURPOSE OF THE STUDY: Calcium phosphate ceramics are synthetic bone substitutes able to fill in bone destruction as a support of the bone growth. This work consisted in an in vitro assessment of osteoblasts and fibroblasts cultures on macroporous calcium-phosphate bone substitutes to analyze the interaction between cells and bone substitute. MATERIALS AND METHODS: The macroporous ceramic was composed of 70% hydroxyapatite and 30% tri-calcium phosphate with known mechanical and physico-chemical properties. Three compounds were processed with different size of macropore and with or without microporosity on their surface. Cells were seeded on discs measuring 10 mm in diameter and 2 mm in thickness. Cellular viability was evaluated by the MTT test for every stage of observation. An histological study to observe the invasion in the depth of discs was performed. Scanning electron microscopy was used to analyze the cellular comportment in contact with the surface of substitutes. RESULTS: An exponential cellular growth was effective on each substitute with the two cellular types. Cells spread on the surface of the compounds covering macropores and colonized the depth of the discs. A size of macropore of 300 microm or more seemed to support this invasion. 15 microm sized interconnections appeared to be effective to allow cell migration between macropores. The cell proliferation was similar on substitutes with or without microporosity. CONCLUSION: Biomaterials currently used as bone substitute are more or less osteoconductive but they have no osteoinductive property. A hybrid association of calcium-phosphate ceramic with osteogenic cells should promote the development of a calcium phosphate compound with osteoinductive capacity.

[Fracture of the odontoid process (author's transl)]. / Fractures de l'apophyse odontoïde (dens) de l'axis. 102 cas dont 73 fractures récentes.

102 cases of fractures of the odontoid process have been seen by the author - 73 recent cases and 29 old ones. It was important to distinguish basal fractures (29 cases), which all united after conservative treatment by reduction and skull traction for six weeks followed by a plaster cast for six to eight weeks, and fractures of the body (44 cases). 41 body fractures were treated conservatively, of which 6 died and only 20 united. The authors consider that treatment by skull traction must always be tried. An eventual indication for surgery can be made at about the 20th day if displacement is found to be present in spite of treatment. Fusion in these cases must be limited to C1-C2. It is best obtained by a combination of wiring and grafting.