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Francesco Pegreffi

Publications and source records attributed to Francesco Pegreffi.

6 recordsLinked to original sources
PubMed2007

Alendronate improves screw fixation in osteoporotic bone.

BACKGROUND: Animal studies have demonstrated the efficacy of the use of bisphosphonates to enhance screw fixation in bone. In this prospective, randomized study of pertrochanteric fractures treated with external fixation, we tested whether systemic administration of bisphosphonates would improve the fixation of hydroxyapatite-coated screws implanted in osteoporotic bone. METHODS: Sixteen consecutive patients with a pertrochanteric fracture were selected. Inclusion criteria were female gender, an age of at least sixty-five years, and a bone mineral density T-score of less than -2.5 standard deviations. Exclusion criteria included bisphosphonate treatment during the two-year period prior to the fracture. Fractures were fixed with a pertrochanteric fixator and four hydroxyapatite-coated pins. Two pins were implanted in the femoral head (pin positions 1 and 2), and two were placed in the femoral diaphysis (pin positions 3 and 4). The patients were randomized either to therapy with alendronate for a three-month postoperative period (Group A) or to no therapy (Group B). The Group-A patients received an oral dose of 70 mg of alendronate per week. The fixators were removed after three months. RESULTS: All of the fractures healed, and no loss of reduction, nonunion, or delayed union was observed. The combined mean extraction torque (and standard deviation) of the pins implanted at positions 1 and 2 (cancellous bone) was 2558 +/- 1103 N/mm in Group A and 1171 +/- 480 N/mm in Group B (p < 0.0005). The combined mean extraction torque of the pins implanted at positions 3 and 4 (cortical bone) was 4327 +/- 1720 N/mm in Group A and 4075 +/- 1022 N/mm in Group B. CONCLUSIONS: These data show that weekly systemic administration of alendronate improves pin fixation in cancellous bone in elderly female patients with osteoporosis. We observed a twofold increase in extraction torque with the pins implanted in cancellous bone. These results support the use of alendronate in the treatment of osteoporotic pertrochanteric fractures to improve screw fixation in the femoral head.

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PubMed2005

Hydroxyapatite-coated external fixation pins.

The aim of this review is to report on studies of hydroxyapatite-coated external fixation pins as a solution to enhance pin fixation. In a highly loaded animal study, three tapered pin types were compared: Type A uncoated, Type B coated with hydroxyapatite and Type C coated with titanium. There was a 13-fold increase in the extraction torque of Type B pins compared with Type A, and a twofold increase compared with Type C pins. Extraction torque was significantly lower compared with the corresponding insertion torque in both Types A (p < 0.001) and C (p = 0.003). Conversely, with the hydroxyapatite-coated pins there was no difference between extraction and insertion torque. In a clinical study of 76 external fixation pins in 19 patients treated with hemicallotasis for osteoarthritis on the medial side of the knee, pin insertion and extraction torque forces were measured. The patients were randomized to be treated with either standard tapered pins or tapered pins coated with hydroxyapatite. Extraction torque of the hydroxyapatite-coated pins was higher than the extraction torque of the standard pins in both cancellous and cortical bone (p < 0.005). In a prospective, randomized clinical study of osteoporotic wrist fractures, extraction torque of the coated pins was higher than with standard pins (p < 0.0001). These studies demonstrate that with the use of hydroxyapatite-coated pins, no deterioration of pin fixation occurs, and that there is no significant pin loosening and infection, regardless of bone type and loading conditions.

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PubMed2005

Dynamic hip screw compared with external fixation for treatment of osteoporotic pertrochanteric fractures. A prospective, randomized study.

BACKGROUND: Although the use of a sliding hip screw is considered to be the preferred treatment for pertrochanteric femoral fractures, we theorized that external fixation could produce clinical outcomes equal to, if not better than, the outcomes obtained with conventional treatment. Furthermore, because external fixation is minimally invasive, we expected a lower rate of morbidity and a reduced need for blood transfusions. Therefore, we compared the two treatments in a clinical trial of elderly patients with pertrochanteric fracture. METHODS: Forty consecutive elderly female patients who had a pertrochanteric fracture were randomized to be treated with either fixation with a 135 degrees four-hole sliding hip screw (Group A) or an external fixation device with hydroxyapatite-coated pins (Group B). The inclusion criteria were female gender, an age of at least sixty-five years, an AO/OTA type-A1 or A2 fracture, and a bone mineral density T-score of less than -2.5. There were no differences in patient age, fracture type, bone mineral density, comorbidities, length of hospital stay, or quality of reduction between the two groups. RESULTS: The average intraoperative time (and standard deviation) was 64 +/- 6 minutes in Group A and 34 +/- 5 minutes in Group B (p < 0.005). The average number of units of blood transfused postoperatively was 2.0 +/- 0.1 in Group A and none in Group B (p < 0.0001). Group B had less pain five days postoperatively (p < 0.05). Varus collapse of the fracture at six months averaged 6 degrees +/- 8 degrees in Group A and 2 degrees 1 degrees in Group B (p < 0.002). No pin-track infections occurred in Group B. The average Harris hip score at six months was 62 +/- 19 points in Group A and 63 +/- 17 points in Group B. CONCLUSIONS: This study showed that external fixation with hydroxyapatite-coated pins is an effective treatment for this fracture in this patient population. The operative time is brief, the blood loss is minimal, the fixation is adequate, and the reduction is maintained over time.

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PubMed2004

HA-coated screws decrease the incidence of fixation failure in osteoporotic trochanteric fractures.

This study was done to determine if elderly patients with trochanteric fractures and with osteoporosis could benefit from treatment with a dynamic hip screw fixed with HA-coated AO/ASIF screws. One hundred twenty patients with AO, A1, or A2 trochanteric fractures were selected. Patients were divided into two groups and randomized to receive a 135 degree-four-hole dynamic hip screw fixed with either standard lag and cortical AO/ASIF screws (Group A), or HA-coated lag and cortical AO/ASIF screws (Group B). Lag screw cutout occurred in four patients in Group A, but not in any patients in Group B. In Group A, the femoral neck shaft angle was 134 degrees +/- 5 degrees postoperatively and 127 degrees +/- 12 degrees at 6 months. In Group B, the femoral neck shaft angle was 134 degrees +/- 7 degrees postoperatively and 133 degrees +/- 7 degrees at 6 months. The Harris hip score at 6 months was 60 +/- 25 in Group A and 71 +/- 18 in Group B. The superior results of Group B can be attributed to the increased screw fixation provided by the HA-coated screws. We recommend lag screws coated with HA for dynamic hip screw fixation, especially in osteoporotic bone.

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PubMed2002

Fixation strength of tapered versus bicylindrical hydroxyapatite-coated external fixation pins: an animal study.

The purpose of this study was to comparatively measure the bone-pin interface strength in two types of hydroxyapatite-coated pins that differed in shape, diameter, and implantation technique. Both pin types are commonly used for tibia fixation. Thirty bicylindrical 5/4-mm stainless-steel pins (Group A) and 30 tapered 6/5-mm stainless-steel pins (Group B) were implanted in the left tibiae of 10 adult sheep. A monolateral fixator was mounted on the pins after implantation. A 5-mm-long bone segment was removed from the tibial mid-diaphysis to ensure high load at the bone-pin interface. Pin insertion torque was 830 +/- 446 N/mm in Group A and 3415 +/- 743 N/mm in Group B (p<0.0001, one-way ANOVA). Six weeks after surgery, the sheep were euthanized and pin extraction torque measured. Pin extraction torque was 1237 +/- 499 N/mm in Group A and 3367 +/- 1512 N/mm in Group B (p<0.0001, Mann-Whitney test). Morphological analysis performed at 60x magnification showed a direct bone-pin contact in both groups. Despite challenging biomechanical conditions, this study showed both pin types to be well-fixed and osteointegrated. Therefore, both pin types are recommended for tibial fixation. However, the tapered pins showed higher extraction torque, an important result for external fixation treatments.

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