Carlo Dall'Oca

Cement augmentation of intertrochanteric fractures stabilised with intramedullary nailing

We studied 80 patients (56 females) with an average age of 84 years (range 80-94). All patients were suffering from osteoporosis (1 or 2 Singh score) and had an unstable intertrochanteric fracture, defined as a fracture with three fragments or more. Patients were divided in group A (40 patients), treated by a cement augmentation technique and group B (40 patients) treated by Gamma Nail conventional technique. Augmentation was performed with MetilMetacrilate (Mendec Spine, Tecres) inserted through the cannulated cephalic screw at its apex. Such parameters were evaluated as the length of operating time, early functional recovery using the Harris hip score, assessment with radiography of the TAD index and development of implant related complications. The HHS average score was 48.2 and 49.31 after 1 month post-operation, 54.37 and 53.56 after 3 months, 54.71 and 56.42 after 6 months, 57.91 and 59.86 after 12 months, in groups A and B, respectively. The average drop of haemoglobin was 1.55 g/dL and 1.05 g/dL, in groups A and B, respectively. Except one joint penetration with the guide wire and some small amount of cement leakage, no other complications (infection, screw cut out and femoral head necrosis) were observed. We believe that in femoral intertrochanteric fractures cement augmentation could improve the mechanical stability of the implant, ensuring early functional recovery.

The biocompatibility of porous vs non-porous bone cements: a new methodological approach

Composite cements have been shown to be biocompatible, bioactive, with good mechanical properties and capability to bind to the bone. Despite these interesting characteristic, in vivo studies on animal models are still incomplete and ultrastructural data are lacking. The acquisition of new ultrastructural data is hampered by uncertainties in the methods of preparation of histological samples due to the use of resins that melt methacrylate present in bone cement composition. A new porous acrylic cement composed of polymethyl-metacrylate (PMMA) and β-tricalcium-phosphate (p-TCP) was developed and tested on an animal model. The cement was implanted in femurs of 8 New Zealand White rabbits, which were observed for 8 weeks before their sacrifice. Histological samples were prepared with an infiltration process of LR white resin and then the specimens were studied by X-rays, histology and scanning electron microscopy (SEM). As a control, an acrylic standard cement, commonly used in clinical procedures, was chosen. Radiographic ultrastructural and histological exams have allowed finding an excellent biocompatibility of the new porous cement. The high degree of osteointegration was demonstrated by growth of neo-created bone tissue inside the cement sample. Local or systemic toxicity signs were not detected. The present work shows that the proposed procedure for the evaluation of biocompatibility, based on the use of LR white resin allows to make a thorough and objective assessment of the biocompatibility of porous and non-porous bone cements.

Antibiotic-Loaded Spacer for Two-Stage Revision of Infected Total Knee Arthroplasty.

Abstract Infection of total knee arthroplasty (TKA) is a challenge in orthopedic surgery. In literature TKA infection is classified according to the time after surgery: acute postoperative; late chronic; acute hematogenous; positive intraoperative microbiological growth. The purpose of this study is to present the results of the use of a preformed antibiotic‐loaded spacer in TKA infections, treated by a two‐stage revision procedure. A series of 19 consecutive patients (20 knees) with a diagnosis of infected TKA were treated from January 2003 to February 2012. Two‐stage reimplantation protocols were completed only in 16 patients and these data were included in the study. We lost three patients at follow‐up. An antibiotic‐loaded preformed articulating polymethylmethacrylate spacer was applied. Patients were observed 1, 3, and 6 months postoperatively and then yearly for clinical and radiographic examination. The mean American Knee Society Score improved from 68.4 preoperatively (range, from 34 to 108) to 112.7 at final follow‐up (range, from 49 to 180). The pain was evaluated as part of clinical score. It improved from an average of 19.3 preoperatively (range, from 10 to 30) to 34.3 at final follow‐up (range, from 10 to 50). The average range of motion improved from 40.1 degrees (range, from 6 to 90 degrees) to 79.3 degrees (range, from 45 to 125 degrees). The use of the spacer allows obtaining a reduction of pain, an improvement of quality of life in the period of time between the two surgical stages and an easier reimplantation of TKA.

The biocompatibility of bone cements: progress in methodological approach

The ideal bone graft substitute should have certain properties and there are many studies dealing with mixture of polymethylmetacrilate (PMMA) and ß-tricalciumphospate (ß-TCP) presenting the best characteristics of both. Scanning Electron Microscopy (SEM), for ultra-structural data, resulted a very reliable in vivo model to better understand the bioactivity of a cement and to properly evaluate its suitability for a particular purpose. The present study aims to further improve the knowledge on osteointegration development, using both parameters obtained with the Environmental Scanning Electron Microscopy (ESEM) and focused histological examination. Two hybrid bone graft substitute were designed among ceramic and polymer-based bone graft substitutes. Based on ß-TCP granules sizes, they were created with theoretical different osteoconductive properties. An acrylic standard cement was chosen as control. Cements were implanted in twelve New Zealand White (NZW) rabbits, which were sacrificed at 1, 2, 3, 6, 9 and 12 months after cement implantation. Histological samples were prepared with an infiltration process of LR white resin and then specimens were studied by X-rays, histology and Environmental Scanning Electron Microscopy (ESEM). Comparing the resulting data, it was possible to follow osteointegration’s various developments resulting from different sizes of ß-TCP granules. In this paper, we show that this evaluation process, together with ESEM, provides further important information that allows to follow any osteointegration at every stage of develop.

Evolution of TKA design

Background and aim of the work : The international literature and analysis of the prosthetic registers highlight a significant relationship between the alignment of the components and the survival of prosthetic implants of the knee. The patient specific instrumentation (PSI) technology exploits the data obtained with the MRN for the production of cutting blocks (CB) useful to a TKA. Revisiting the recent international literature, comparing the results of the conventional method and PSI, numerous studies confirm a statistically significant difference of inliers (± 3 degrees) for HKA. The purpose of this retrospective study was to investigate whether these statistically significant difference is also present in our group. Methods : Postoperative radiographic measures of alignment based on a mechanical limb axis (hip-knee-ankle angle, HKA) of 180° were sought. A range of 180° ± 3° varus/valgus was defined as optimal for mechanical axis. Results: The percentage of knees that had a HKA within ±3° of the desired value was 92.2. Conclusion: the CB did accurately produce the desired HKA. The PS system is an effective and reproducible, whose organizational effort is fully justified.