Introduction. Plain radiograph underestimates the lysis extent while bone defect determines acetabular revision. We determine the multislice computed tomography (CT) efficacy with metal-artifact minimization to calculate the volume, extent and location of lytic lesions around a loose acetabular cup.

Patients and Methods. 48 hips with a loose acetabular cup were evaluated before cup revision. Multislice CT scans with metal-artifact minimization (Toshiba-MEC CT) were done. Scans were taken at 135 kV and 250 mA to maximize the resolution and bone contrast. CT slice thickness was 3 mm and reconstruction index 1.5 mm. Evidence of osteolytic lesion on these scans was compared with plain radiographs and with intraoperative findings. Bone defects were classified according to Paprosky.

Results. Acetabular lysis were found in the radiographs of 18 hips and in the CT scans of 36 hips. The most frequent locations of osteolysis were medial (32 hips) and posterior walls (23 hips). Radiographs underestimated the extent of the lysis: there were 28 hips with radiographic type 1 defects and 16 hips with CT defects; 6 and 11 with type 2; 8 and 10 with type 3A; and 6 and 11 with type 3B respectively (Wilcoxon test, p< 0.001). The mean volumetric bone loss was 35.4 cm3 . Intraoperative findings confirmed CT findings.

Conclusions. Multislice CT scans with metal-artifact minimization is more sensitive for identifying and quantifying osteolysis around the cup than are plain radiographs. Since CT scans allow us to show the extent and location of the osteolysis, they are useful to plan cup revision.

Aim: To assess the clinical results, radiographic fixation and polyehtylene wear of a second generation cementless porous coated acetabular cup for a follow-up of 9.6 years

Material and Methods: 81 Duraloc 500 (De Puy) cups with polyethylene (PE) Enduron implanted between 1992–1995 are analysed. The mean follow-up was 9.6 years. Clinical results and radiographic fixation according to Jonhston et al. and according to Engh et al. were evaluated. PE mean wear and so-called “bedding in” process was estimated with anteroposterior pelvic radiographs which were digitized and analysed using a software package with Sychterz method. X-rays were measured at 6 weeks (zero position), 6 months, 12 months and annually thereafter. In all cases a Profile (De Puy) femoral stem was used

Results: There was 1 PE exchange because of a later dislocation (Kaplan-Meier survivorship 98.67 % at 10 years). All cups were osseointegrated. There was no osteolysis (Kaplan-Meier 100% at 10 years). There were no PE liner ruptures. Zero position (PE wear at 6 weeks) for PE was 0.1651 + 1339 mm and mean wear was 0.1108 + 0.793 mm.

Conclusions: All cups, except one, improved clinical results and showed stable fixation. There was no acetab-ular osteolysis in this series. In spite of a low zero position, mean PE wear was similar to other cups.

Purpose: To analyse prolonged combinations of oral intracellular-effective antibiotics plus two-stage exchange surgery for treatment of chronic THA and TKA infections.

Materials and Methods: Definition of infected case: more than 3 months from surgery; multiple positive intraoperative cultures and/or active fistulae.

33 patients were treated from 1996 to 2002: 8 THA, 5 hip hemiarthroplasties, 20 TKA.

Bacteriology: 24 Staphylococci of which 16 were methycillin-resistant, 7 multi-resistant Gram-negative, 2 Cory-nebacteriae; 7 polymicrobian.

Antibiotic therapy: two simultaneous oral antibiotics, selected according to bacterial sensitivity and intracel-lular effectiveness (rifampin, ofloxacin, ciprofloxacin, levofloxacin, trimethoprim-sulfamethoxazole, fosfomicin, linezolid, doxiciclin), were used on an outpatient basis (between 1st and 2nd surgery, and after 2nd surgery until serological normalization). Patients received intravenous antibiotics and were in-hospital only for one week after surgery.

Surgery: two-stage exchange with 2nd stage delayed until clinical and serological normalization.

Healing of infection: absence of clinical, serological and radiological evidence of infection along all follow-up.

Prospective follow-up: 24-96 months.

Results: Healing of infection: 32/33 patients (97%).

Treatment failure: 1 patient (TKA) (3%).

THA: 8/8 infections healed: 1 Girdlestone patient (1st stage of exchange) rejected reimplantation; 7 two-stage exchange (good/excellent objective and subjective result).

Hip hemiarthroplasty: 5/5 infections healed: 3 Girdlestone (1st stage of exchange surgery, 2nd stage rejected because of hemiplegia or Alzheimer); 2 two-stage exchange (good/excellent objective and subjective result).

TKA: 19/20 infections healed: 3 resection-arthroplasty (1st stage of exchange surgery, 2nd stage rejected because of Buerger, cirrhosis or Alzheimer); 17 two-stage exchange (15 good/excellent objective and subjective results, 1 patient needed a debridement 2 months after 2nd surgery because of prolonged aseptic drainage and healed uneventfully, 1 failure described).

Conclusions: Prolonged combinations of oral intracellular-effective antibiotics associated with two-stages exchange surgery is a promising alternative for treating deep chronic THA and TKA infections. Longer follow-up and larger series are necessary.

Introduction and purpose: This is a prospective analysis of the clinical and radiographical results of two different types of PE, both associated to the same kind of prosthesis (Zimmer-Centerpulse).

Materials and methods: A total of 101 Allofit shells were analyzed; 56 had Sulene-PE (nitrogen sterilized) and 45 had Durasul highly cross-linked PE, associated to an Alloclassic stem (femoral head: 28 mm). They were all implanted between 1999 and 2002. Mean follow-up was 29.4 months for Sulene-PE and 25.3 for Durasul-PE. PE wear was assessed by means of image digitalization with special software (AutoCAD 14R) after six weeks (initial settling or position zero), after 6 and 12 months and on a yearly basis.

Results: Three cases dislocated and were thus excluded from the study. There were no infections. All cases assessed had good clinical and radiological results. There were no instances of implant loosening. There were no radiolucent lines, osteolysis, cortical hyperthrophy or proximal osteopenia. On the initial radiograph (position zero), the distance between the axes of the femoral head and those of the shell was 0.30+0.094 mm for the Sulene-PE group and 0.20+0.074 for the Durasul-PE one (p=0.029). Mean wear, taking position zero as a reference point, was 0.1035+0.0686 and 0.0819+0.078 (p=0.108) respectively.

Conclusions: In spite of the higher error rates found in the wear measurements of the Allofit cup, a greater position zero was found in Sulene-PE than in Durasul-PE. Although mean wear was higher in Sulene-PE than in Duarsul-PE, the differences found were not significant 3 years postop.

Introduction and purpose: The study analyzes the efficiency of multislice computerized tomography with metal artifact reduction to calculate the volume, extent and location of osteolysis around a loosened acetabular shell.

Materials and methods: An assessment was made of 48 hips with a loose shell before they were revised with multislice-CT with metal artifact reduction (Toshiba-MEC CT). The slices were taken at 135 kV and 250 mA in order to maximize resolution and bone contrast. Slice width was 3 mm and the reconstruction index 1.5 mm. The osteolytic lesions found on the CT were compared with simple radiographs. Bone defects were classified using Paprosky’s classification.

Results: Acetabular osteolysis was found in the radiographs of 30 hips and in the CTs of 36. Radiographs under-represented the extent of osteolysis: there were 28 hips with a type 1 radiographic defect and 18 with a type 1 CT defect; 6 and 14 with type 2; 8 and 6 with type 3A; and 6 and 10 with type 3B respectively (Wilcoxon test, p=0.004). The mean volumetric loss of bone defects was 35.4 cm3 . Intraoperative findings confirmed the CT findings.

Conclusions: Multislice CT with metal artifact reduction is more sensitive than simple radiographs when it comes to identifying and quantifying osteolysis around an ace-tabular shell. Since multislice-CT shows us the extent and location of osteolysis, it is of great help at the time of planning a revision of the acetabular shell.

Aims: internal fixation is not generally accepted as election treatment for displaced femoral neck fractures in patients older than 70. Results and risk factors are analysed in this later group of patients. Patients and Methods: 155 patients older than 70 with displaced femoral neck fractures were treated with closed reduction and parallel cannulated screws and prospectively followed for 2 years. Patients were allowed postoperative full weight bearing with aids. Quality of reduction and osteosynthesis were radiologically analysed. Results: 24 patients (15%) were lost. At the end of follow-up 52% of patients were asymptomatic, 13% had mild pain, 28% suffered a 2nd surgery (arthroplasty) and 7% were badly ill for aditional surgery. 57% presented uncomplicated consolidation, 28% non-union and 8% ischemic necrosis. Poor-quality reduction (p= 0.039) and poor-quality osteosynthesis (p=0.051) were significant risk factors for failure. A higher age (p=0.36), displacement (Eliason criteria) (p=0.26) and delay in surgery (p=0.53) were not significant risk factors. Conclusions: closed reduction and percutaneous fixation of displaced femoral neck fractures achieves good/fair results in only 65% of patients older than 70 years. Poor-quality reduction and osteosynthesis are risk factors for clinical and/or radiological failure.

Aim: Mean radiographic polyethylene wear can not distinghish between so-called Òbedding-inÒ and true wear in porous-coated cups (Sychterz 1999). Wear performance of two different generations of the same cement-less porous-coated cup are compared. Material and Methods: 83 Harris-Galante I (HGI) (32mm femoral head) and 93 Harris-Galante II (HGII) (28mm) cups are analyzed. The average follow-up was 11.5 yrs for HGPI and 6.7 years for HGPII cups. Anteroposterior pelvic radiographs (at 3 and 6 months and annually thereafter) were scanned digitally and linear wear was estimated using a software package with the Sychterz method. All radiographs were made following the same protocol. Results. Postoperative bedding-in was: 0.15±0.04 mm for HGI and 0.11±0.02 for HGII cups (p< 0.001). Femoral head penetration at the end of follow-up was: 1.50±0.28 mm for HGI and 0.85±0.01 for HGII. Mean wear excluding bedding-in was: 0.13±0.23 mm/year for HGI and 0.11±0.09 for HGII (p=0.740). The femoral head penetration rate was highest in the þrst two years and then decreased with the time and was similar in both groups. Conclusions: The digitized Sychterzñ method allows us to determine bedding-in and true polyethylene wear. The second generation cups show a decrease in the bedding-in process, but do not have a lower wear rate.

Aim: To assess the long-term results of a series of porous-coated anatomic cementless total hip prostheses. Material and Methods: A total of 91 PCA (How-medica) total hip arthroplasties performed between 1984–1988 were analyzed with a mean follow-up of 13.5 years. Clinical results were assessed according to Merle DñAubignŽ-Postel score. Radiographic þxation was assessed according to Engh et al. Results:Thigh pain (17 hips) was correlated with unstable þxation (p=0.0096). Thirty-one cups and six stems were revised. Radiographic loosening ocurred in 21 cups and 12 stems. Mean polyethylene wear was 0.16 mm/year. Cup loosening was related with an acetabular wear equal to or more than 2 mm (p=0.0018) and an small cup size (p=0.015). Stem loosening was related with poor femoral canal þlling (p=0.046). Fifty (54.9%) hips had femoral osteolysis and were related with polyethylene wear of more than 2 mm (p=0.0015) and with hips with poor femoral þlling (p=0.0285) and unstable þxation (p=0.00005). Conclusions:The PCA cup has had worse results than the stem. Cup loosening is related with the acetabular wear and cup size. The frequent proximal femoral osteolysis is associated with unstable þxation and poor femoral þlling

Introduction and Objectives: This is a prospective analysis of clinical and radiographic outcomes of total hip prosthesis with alumina-on-alumina friction coupling implants performed at two hospitals.

Materials and Methods: This study analyzes 60 prostheses with alumina-on-alumina friction coupling (Ceraver-Osteal) (May 1999-May 2002). The Cerafit cup was used in association with 32 Multicone-HAC stems and 28 Anatomic-HAC. Of these cases, 36 were male, and 24 were female, with average age being 47.05+/−12.60 years. Mean follow-up time was 2.3 years. There were no lost or revised cases. Radiographic analysis was done according to Johnston et al., and wear was assessed using the Sychterz method in a special computer program (Auto-CAD R14).

Results: All cases had good clinical and radiographic outcomes. There were no revisions or loosening of the implants. There was one dislocation and one intraoperative fracture, which were both treated by conservative means. There were no infections. The distance between the centres of the femoral head and the cup on the initial radiograph (position zero) was 2.49+/−0.70mm. This measurement stayed constant with time, and no changes were observed associated with so-called early wear or initial seating. Mean wear with respect to a reference of position zero was 0.0184+/−0.0187. This figure is below the error level of the measuring system and thus is not measurable.

Discussion and Conclusions: The alumina-on-alumina prosthesis (Ceraver) yields positive clinical and radiographic results at 4 years. Even though the alumina partially distorts the radiographic image, no evidence of early wear due to seating of the components was observed at four years of follow up using the Sychterz digitalized method.

We have analysedin the results of 24 femoral lengthenings in 23 patients operated on between 1993 and 2000, using a gradual elongation intramedullary nail (Albizzia). Of the 23 patients, 22 had femoral deficiency and one was of short stature. Their mean age was 16.9 years. Technical difficulties encountered during the procedure were mild or moderate in 18 femora and severe in six femora. Distraction was obtained by 15 ratchetings per day (1 mm/day).

There were 18 excellent results although in two patients this was achieved after the development of a pseudarthrosis which required further surgery. There were four good and two fair results in which the lengthening obtained was at least 3 cm less than had been projected. The consolidation index was 35.2 days/cm. No patient had associated long-term stiffness of the knee.

Femoral lengthening using an elongation nail gives good results and is a comfortable procedure.

Between 1972 and 1990, we performed 168 primary low-friction arthroplasties in 125 patients with acetabular protrusion. Twelve hips were lost to follow-up within eight years and eight which became infected were excluded from the final study. Of the 148 hips remaining, 62 with a mild protrusion were classified as group 1, 54 with moderate or severe protrusion as group 2 and, after 1985, 32 with moderate and severe protrusion which required bone grafts as group 3. The mean follow-up was 18.3 years (3 to 24) for group 1, 17.4 years (8 to 22) for group 2 and ten years (8 to 13) for group 3.

There were 31 revisions of the cup, 12 in group 1 and 19 in group 2. According to the Kaplan-Meier analysis the overall rates at 20 years were 21 ± 10.79% in group 1 and 37 ± 11.90% in group 2. There have been 43 radiological loosenings: 22 in group 1, 21 in group 2 and none so far in group 3, at ten years. The overall loosening rates at 20 years were 42 ± 14.76% in group 1 and 49 ± 19.50% in group 2. The grafts were well incorporated in all group-3 hips, and the bone structure appeared normal after one year.

The distance between the centre of the head of the femoral prosthesis and the approximate true centre of the femoral head was less in group 3 than in groups 1 and 2 (p < 0.01). According to the Cox proportional-hazards regression this was the single most important factor in loosening of the cup (odds ratio 1.11; 95% CI 1.05 to 1.18/mm). Better results were obtained in moderate and severe protrusions reconstructed with bone grafting than in hips with mild protrusion which were not grafted.