Rocco Paolo Pitto | PubMed Health

PubMed2006

Periacetabular bone changes after uncemented total hip arthroplasty evaluated by quantitative computed tomography.

BACKGROUND: There are few dual X-ray absorptiometry (DXA) studies on periacetabular bone density changes after cup implantation. This study was designed to analyze the load-transfer mechanism and stress pattern of periacetabular cortical and cancellous bone after implantation of a ihemispherical titanium alloy press-fit cup with alumina-alumina pairing in vivo. We introduced a novel method of computed tomography (CT)-assisted osteodensitometry. METHOD: We investigated 26 hips (26 patients) with osteoarthritis using conventional sequential CT examinations performed within the first 10 days after implantation, and after a mean period of 1.1 years postoperatively. Bone density of full, cancellous and cortical bone (mgCaHA/mL) was measured. RESULTS: At the time of follow-up, the mean bone density values of the cortical bone cranial to the cup increased by 3.6% (p = 0.03) while the cancellous bone density decreased by 18%. Cancellous bone loss was greater in the region ventral to the cup (-35%) than in the dorsal region (-30%). Cortical bone density decreased ventral to the cup (-6.4%). All these changes were statistically significant. The bone density changes in the dorsal cortical region were not significant. INTERPRETATION: The method presented is an excellent tool for detailed measurement of bone density changes around the cup after total hip arthroplasty, and allows a thorough assessment of stress shielding phenomena in vivo. The hemispherical titanium alloy press-fit cup is a rigid implant which stress shields cancellous bone and enhances load transfer to the cranial cortical bone. Further investigations will demonstrate the impact these factors have on the long-term results of the implant, and may allow a type-related predictable prognosis of the longevity of the prosthesis.

Absorptiometry, Photon↗

PubMed2005

Inter- and intraobserver assessment of periacetabular osteodensitometry after cemented and uncemented total hip arthroplasty using computed tomography.

INTRODUCTION: This study was initiated to evaluate the reproducibility of a novel method for measuring the periacetabular bone density after insertion of cemented and uncemented acetabular cups using CT in vivo. MATERIALS AND METHODS: CT scans were obtained from 20 patients after cemented polyethylene cup implantation (ZCA, Zimmer, USA) and 20 patients after uncemented titanium alloy cup fixation (Cerafit, Ceraver, France). A manual segmentation of cancellous and cortical pelvic bone ventral, dorsal and cranial to the cup was undertaken. Values are given in Hounsfield units. Inter- and intraobserver studies were conducted using a special analysis software tool. To define the reproducibility of the method, all measurements were evaluated according to Bland and Altman. RESULTS: For both cemented and uncemented acetabular cups, reproducibility of bone density measurement for cortical and cancellous bone cranial, ventral and dorsal to the cup was high. There was no significant difference between the intraobsever study (two repeated measurements) and the interobserver study (two investigators), indicating the reproducibility of the method independent of the investigator. CONCLUSION: In conclusion, the periacetabular bone density measurement as conducted in this CT study is a new reproducible method for in vivo evaluation of cortical and cancellous pelvic bone after cemented and uncemented acetabular cup implantation. In vivo CT measurements will allow a thorough assessment of periacetabular stress-shielding phenomena.

Acetabulum↗

PubMed2004

The Wagner spherical osteotomy of the acetabulum. Surgical technique.

BACKGROUND: The purpose of this study was to evaluate the long-term clinical and radiographic results of spherical acetabular osteotomy, performed with the surgical technique described by Wagner, in patients with hip dysplasia. METHODS: The results of the first twenty-two spherical osteotomies performed by one surgeon at one institution were reviewed at a minimum of twenty years (median, 23.9 years; maximum, 29.3 years) postoperatively. Preoperative and follow-up radiographic measurements included the lateral and anterior center-edge angles, acetabular index angle, and acetabulum-head index of Heyman and Herndon. Anteroposterior radiographs of the pelvis were evaluated for the presence of joint congruency, joint-space narrowing, increased sclerosis of the subchondral bone, and bone cysts. Clinical evaluation was performed with use of the Harris hip score. RESULTS: Osteotomy improved the mean lateral center-edge angle from -2 degrees to +13 degrees and the mean acetabulum-head index from 52% to 72%. The mean postoperative anterior center-edge angle was 23 degrees (range, -1 degrees to 62 degrees ). Seven (32%) of the twenty-two hips were converted to a total hip replacement. At the latest follow-up examination, the average Harris hip score of the remaining fifteen patients was 86 points (range, 50 to 100 points). The clinical result was rated good or excellent for eleven of the fifteen patients. At the latest follow-up examination, the severity grade of the osteoarthritis was unchanged in thirteen hips. Only three of the nine hips that subsequently required a total hip replacement or that showed progressive osteoarthritis had been congruent after the index operation, whereas ten of the thirteen hips that did not require total hip replacement or show progressive osteoarthritis had been congruent after the index operation. The twenty-year Kaplan-Meier survival estimate, with conversion to total hip replacement as the end point, was 86.4% (95% confidence interval, 63.4% to 95.4%). The twenty-five-year survival estimate was 65.1% (95% confidence interval, 35.6% to 83.7%). CONCLUSIONS: The Wagner spherical osteotomy prevented progression of osteoarthritis both clinically and radiographically in a high proportion of patients with residual hip dysplasia who were followed for a minimum of twenty years. Operative restoration of joint congruency is associated with a satisfactory long-term outcome in a very high proportion of cases.

Acetabulum↗

PubMed2003

Uncemented acetabular components with polyethylene or alumina liners.

Sixty consecutive patients (60 hips) were allocated in two matched-pair groups. Patients were matched for age, gender, body mass index, level of activity, and bone stock. Both groups received an uncemented total hip arthroplasty with a modular press-fit cup and an alumina femoral head. In the first group, an acetabular liner made of polyethylene was used; in the second group, an alumina liner. Both groups were followed for a minimum of 5 years. No hip required revision, and there was no radiographic evidence of aseptic loosening in either group. Mean Harris hip score was 94.7 (87.1-99) points in the polyethylene group and 93 (88.5-100) points in the alumina group.

Acetabulum↗

PubMed2003

Treatment of the dysplastic acetabulum with Wagner spherical osteotomy. A study of patients followed for a minimum of twenty years.

BACKGROUND: The purpose of this study was to evaluate the long-term clinical and radiographic results of spherical acetabular osteotomy, performed with the surgical technique described by Wagner, in patients with hip dysplasia. METHODS: The results of the first twenty-two spherical osteotomies performed by one surgeon at one institution were reviewed at a minimum of twenty years (median, 23.9 years; maximum, 29.3 years) postoperatively. Preoperative and follow-up radiographic measurements included the lateral and anterior center-edge angles, acetabular index angle, and acetabulum-head index of Heyman and Herndon. Anteroposterior radiographs of the pelvis were evaluated for the presence of joint congruency, joint-space narrowing, increased sclerosis of the subchondral bone, and bone cysts. Clinical evaluation was performed with use of the Harris hip score. RESULTS: Osteotomy improved the mean lateral center-edge angle from -2 degrees to +13 degrees and the mean acetabulum-head index from 52% to 72%. The mean postoperative anterior center-edge angle was 23 degrees (range, -1 degrees to 62 degrees ). Seven (32%) of the twenty-two hips were converted to a total hip replacement. At the latest follow-up examination, the average Harris hip score of the remaining fifteen patients was 86 points (range, 50 to 100 points). The clinical result was rated good or excellent for eleven of the fifteen patients. At the latest follow-up examination, the severity grade of the osteoarthritis was unchanged in thirteen hips. Only three of the nine hips that subsequently required a total hip replacement or that showed progressive osteoarthritis had been congruent after the index operation, whereas ten of the thirteen hips that did not require total hip replacement or show progressive osteoarthritis had been congruent after the index operation. The twenty-year Kaplan-Meier survival estimate, with conversion to total hip replacement as the end point, was 86.4% (95% confidence interval, 63.4% to 95.4%). The twenty-five-year survival estimate was 65.1% (95% confidence interval, 35.6% to 83.7%). CONCLUSIONS: The Wagner spherical osteotomy prevented progression of osteoarthritis both clinically and radiographically in a high proportion of patients with residual hip dysplasia who were followed for a minimum of twenty years. Operative restoration of joint congruency is associated with a satisfactory long-term outcome in a very high proportion of cases.

Acetabulum↗

PubMed2002

Prophylaxis against fat and bone-marrow embolism during total hip arthroplasty reduces the incidence of postoperative deep-vein thrombosis: a controlled, randomized clinical trial.

BACKGROUND: Clinical and experimental studies have suggested that the maximum risk of thrombogenesis occurs during, rather than after, total hip arthroplasty. With use of conventional cementing techniques, insertion of a femoral component results in marrow embolization of tissue thromboplastin into the veins of the proximal part of the femur, leading to activation of the clotting cascade and thrombogenesis. We hypothesized that an operative technique designed for the prevention of fat and bone-marrow embolism can also reduce the incidence of postoperative deep-vein thrombosis and pulmonary embolism. METHODS: A total of 130 consecutive patients with osteoarthritis who were to have a primary total hip arthroplasty were randomly assigned to one of two groups. One group consisted of sixty-five patients (sixty-five hips) who had the femoral component inserted with our standard cementing technique without use of a bone vacuum, and the other group included sixty-five patients (sixty-five hips) who had the femoral component cemented with use of a bone-vacuum technique. In the hips managed with the bone vacuum, suction (-800 mbar) was applied to a drainage cannula placed along the linea aspera of the femur in order to prevent an increase in intramedullary pressure during the insertion of the stem. We measured the incidence of intraoperative fat and bone-marrow embolism with use of echocardiography and a transesophageal probe and the incidence of deep-vein thrombosis with use of serial duplex ultrasonography on the day before the operation and on postoperative days 4, 14, and 45. All patients were managed with prolonged pharmacological prophylaxis (low-molecular-weight heparin) against deep-vein thrombosis. RESULTS: The control group had significantly more severe and prolonged echocardiographic embolic events than did the group managed with the bone-vacuum technique (p < 0.05). A cascade of fine echogenic particles or embolic masses with a diameter of < or =5 mm was observed during the insertion of the stem in fifty-nine hips (91%) in which our standard cementing technique was used and in ten hips (15%) in which the bone-vacuum cementing technique was used. Deep-vein thrombosis was detected on postoperative day 4 in twelve patients (18%) in the control group and in two patients (3%) in the group managed with the bone-vacuum technique; the difference was significant (p < 0.05). CONCLUSIONS: Intraoperative prophylaxis against fat and bone-marrow embolism during total hip arthroplasty with cement can reduce the incidence of postoperative deep-vein thrombosis. We now use the bone-vacuum technique routinely in all total hip arthroplasties performed with cement.

Arthroplasty, Replacement, Hip↗