Introduction

Acute poliomyelitis is a very rare disease in western countries, however the remnant of the pathology can be find among the adult patients. In poliomyelitis, sensation is normal and patients may suffer from painful etiologies. Total knee arthroplasty (TKA) with non-hinged or semi hinged prosthesis systems may be a good options to relief the pain in poliomyelitic patients, however the knee remains unstable. Using the hinged system implant may be the good option to resolve the late. Although the main concern in case of hinged implant usage is the mechanical stress which is directly transferred to the bone surface in contact with the implant. This may leads to implant mobilization and consequently failure.

Introduction

Wolff's Law proposes that trabecular bone adapts in response to mechanical loading and that trabeculae align with the trajectory of predominant loads. The current study is aimed to investigate trabecular orientation in the tibia in patients with osteoarthritis of the knee. Consistent with Wolff's Law, it was hypothesised that orientation would reflect the mechanical loading of the joint and hence that there would be a correlation between the trabecular orientation and the mechanical axis of the lower limb.

The Gpsystem Medacta vision system is composed of an infrared camera that produces and receives infrared rays reflected by almost 3 reflectors mounted on different rigid body devices (F=femoral, T=tibial, G=guide), in order to determine its position with an error lower than 0.35mm. Data received from this vision system are than elaborated by the Cinetique Gpsystem Version 1.0 system in order to determine the correct cutting guide positioning both for the femur and the tibia. The cutting guide is moved on different planes by 5 electric engines applied on 5 no ending screws.

The first step of this system is determining, with the F and the T rigid bodies, patient’s lower limb kinematic in order to evaluate its mechanical axis, its flexion-extension range of movement and its pathological deviations. The second step is evaluating anatomical landmarks to find out the correct degrees of tibial and femoral cuts: these landmarks are the medial and lateral tibial glena, the distal femoral condyles, the posterior femoral condyles, the anterior femoral cortex, the tibial tuberosity, the Whiteside line and the epycondilar axis (each anatomical landmark is identified by multiple points in order to decrease possible errors). The third step is applying the cutting guide and the Grigid body on the femoral clamp in order to estimate the correct level for the tibial cut than, once the tibial osteotomy is done the vision system controls its correct execution and the soft tissue balancing of the knee. The fourth step is calculating with the Gpsystem the correct orientation of the femoral cutting guide and checking its positioning and cutting execution. The last step is applying the test-prosthesis verifying the mechanical axis of the knee and than assembling the definitive prosthesis.

Since now we have applied 10 Cinetique knee prosthesis with the Medacta computer navigation system with good results and good positioning of the prosthesis

Medacta computer navigation system for Cinetique knee arthroplasty is innovative for its simple cutting guide and movement device both in their hardware than in their way of using and for a simpler software interface; these characteristics allows faster surgeon technique learning, shortening of surgical time and a better prosthesis positioning.

Compromised patellar bone stock poses significant the chnical problems in primary and revision knee arthroplasty. In these situations, traditional approaches have included: non resurfacing, patellectomy, patellar bone grafting, ‘Gull-Wing’ osteotomy. A new material (Trabecular Metal) fabricated using a tantalum metal and vapor deposition techhnique that create a metallic strut configuration with 80%porosity, and physical and mechanical properties similar to bone has been introduced. The authors studied the short-term results following patellar resurfacing using trabecular metal patella in primary and revision total knee arhroplasty (TKA).

Nine patients undergoing primary (2 cases) or revision (7 cases) TKA with the use of a trabecular metal patella were evaluated at a mean of 16 months follow-up. All patients had marked patellar bone deficiency precluding resurfacing with a standard cemented patellar button. The all polyethylene patela was cemented into the trabecular metal base and the remaining patella bone stock; additional fixation was provided by # 2 non absorbable sutures through the peripheral holes on the metal shell.

Revision TKA may be complicated by severe patellar bone loss that preclude implantantion of a standard cemented patellar component. Several options including patellectomy, non resurfacing and osteotomy or grafting of remaining bony shell have been proposed. It is rare in primary knee arthroplasty that the patella has been so eroded that resurfacing is not feasible. Trabecular metall patella may be indicate in the complex revision or even primary knee arthroplasty in which all that remains of the patella is a thin shell of anterior cortical. The short-term results of patellar resurfacing with trabecular metal have demonstrated favorable results.

The authors studied the short-term results following patellar resurfacing using trabecular metal patella. Ten patients underwent primary (2 cases) or revision (8 cases) TKA with the use of a trabecular metal patella and were evaluated at a mean follow-up of 24 months. All patients had marked patellar bone deficiency or patellar absence precluding resurfacing with a standard cemented patellar button. The all polyethylene patella was cemented into the trabecular metal base and the remaining patella bone stock; additional fixation was provided by non-adsorbable sutures through the peripheral holes on the metal shell. No intraoperative complications occurred. There was no displacement of any trabecular metal patellar component and no patellar fractures. The fixation appeared excellent at three to six months radiographic evaluation with uniform bone contact in the peripheral regions in both lateral an Merchant radiographic views. The mean Knee Society scores improved in all patients.

Introduction Total hip arthroplasty in patients affected by major dysplasia poses great surgical difficulties due to insufficient primary acetabulum, small femoral canal, excessive anteversion of the femoral neck, traction on the neurovascular structures, muscular imbalance that is difficult to restore, and marked epiphyseal rising. In this study we present our experience in lowering and arthroplasty in major hip dysplasia, obtained by shortening osteotomy achieved in a single stage, using techniques designed to diminish possible risks.

Materials and methods From 1989 to 2000 we treated 20 patients (27 operations, 7 bilateral) at our institute who were affected by the sequela (lowering of the prosthesis) of Eftekhar Grade-C (11 cases) or Grade-D (16 cases) congenital luxation of the hip. Mean follow-up was 63 months. Clinical results were assessed before and after surgery according to the Merle D’Aubigné method. We also evaluated the presence and degree of Trendelenburg position and the possible use of shoe lifts. The radiographic results of the hip prosthesis were assessed by the Gruen and Dee Lee methods for the stem and cup respectively.

Results The mean preoperative clinical score according to the Merle D’Aubigné classification was 3 ± 1 for pain, 3 ± 1 for walking, and 4 ± 2 for movement. The preoperative Trendelemburg position was very marked in all patients. In 18 cases out of 27 a shoe lift was used with a mean height of 60 mm ± 10. We performed a “Z” osteotomy in 14 cases and an oblique osteotomy in 13 cases. The postoperative mean clinical score was 6 ± 1 for pain, 6 ± 1 for walking, and 5 ± 1 for movement. Postoperative Trendelemburg position was present in 19 cases, and 9 cases out of 27 still used a shoe lift with a mean height of 30 mm ± 10. Movement of the cup and stem was observed at 84 months and 112 months’ follow-up respectively, which required revision surgery.

Conclusions The choice between oblique and Z osteotomy depends on two parameters: the surgeon’s experience and the extent of femoral resection. Z osteotomy may be more difficult to perform technically, but it enables better adaptation of the prosthesis to the femoral segments for resections over 35 mm. No significant differences in time to unite were observed between oblique and Z osteotomies.

Introduction: The aim of study was to evaluate the prevalence of microbiological isolates obtained from patients admitted to a 308-bed university-affiliated adult and children orthopaedic hospital of northern Italy (with more than 16.000 admissions per year), during a three year period (2000–2002), and, to analyze modifications during this period with regard to the prevalence of methicillin-resistant staphylococci strains.

Material and Methods: A retrospective study was conducted using laboratory records from 2000 to 2002 (2003 in progress) concerning bacterial and yeast isolates from all specimens sent to microbiological laboratory for culture. The specimens came from 8 surgical, 1 intensive care, 1 oncologie and 1 physiotherapy wards and included samples taken at surgical intervention, as like as at patient bed. Antimicrobial susceptibility testing results were also collected. All data were stored in an electronic database for statistical analysis.

Results: Between 2000 and 2002 a total of 8302 clinical specimens have been cultured and they yielded to 2978 isolates from 2653 positive samples. The prevalence of positive cultures form 24.8% in 2000 to 36.7% in 2002 and the isolated organisms are shown in table 1. Gram positive bacteria represent more than 70% of isolates and staphylococci are the most common organism (almost 50%). Staphylococcus epidermidis and other coagulase-negative staphylococci prevalence raised during the period 2000–2002 (respectively 25.4% to 33.4%, and 3.3% to 6.5%). Methicillin resistance rate resulted, 27.1% to 34.9% for Staphylococcus aureus, 37.6% to 28% for Staphylococcus epidermidis, and 33.3% to 42.1% for other coagulase-negative staphylococci. No difference in methicillin sensitivity was found between staphylococci isolated from surgical sites and other samples (urine, blood, sputum, throat swab).

Conclusions: Knowledge of the local epidemiology of pathogens in a surgical/orthopaedic hospital is critical in formulating policies on infection control. Amongst these rules the choice of antibiotic prophylaxis should be taken after analysis of bacteria prevalence and their antibiotic sensitivity.

Valgus knee is a complex deformity, characterised by varying degrees of flexion, external rotation and valgus deviation. Contracture of external ligamentous structures makes correction and soft tissue balance often difficult and may lead to persistent post-operative instability. Further problems include patellar tracking, bone defects, especially at the external femoral condyle, and the risk of external popliteal sciatic (EPS) nerve palsy after surgery. Krackow distinguished three types of valgus knee: type 1 with integral medial peripheral structures; type 2 with severe medial structure laxity and impossibility to correct passively; and type 3 which is the sequela of over-correction tibial osteotomy.

From 1996 to 2003 we performed 64 fusions due to valgus knee in 41 females and 23 males, aged between 55 and 76 years (mean 67.5). Of these, 52 deformities were type 1, nine type 2, and three type 3. For type-1 lesions we always used prostheses with posterior stabilisation (PS), and balanced the capsulo-ligamentous structures. In type-2 lesions we used a vincolo condilare prosthesis with CCK in two cases and a cerniera prosthesis in two cases, whereas in the remaining five cases we used a PS prosthesis. In type-2 deformities we used a PS prosthesis with a modular tibial component with metal augments. Mean follow up was 45 months.

Radiographically, valgus deformity fell from 22.4° (10° min – 35° max) to 5.4° (3° min – 9° max). Post-operative results, according to the HSS score, were excellent in 51 cases, fair in 11 cases, and poor in two cases, due to the need to perform revision in two stages in an infected prosthesis 6 months after surgery in one case, and aseptic loosening in another.

Valgus knee due to arthritis can be successfully treated by total knee arthroplasty using various techniques, according to the clinical severity. EPS nerve palsy has been cited as a potential problem in total knee arthroplasty. We did not observe this complication in our series, probably because we maintain the knee in continuous slight flexion for the first 18–24 h.

Patellar tracking is the most common complication observed following total knee arthroplasty. It may constitute a minor disorder or even frank dislocation. Its main cause is a rotation defect in the prosthetic components. CT is the most reliable instrumental test to assess this rotation defect, and an excellent aid for planning a possible revision operation.

From January 1999 to November 2003 we treated 33 patients with a total of 35 painful knees using TC prostheses. Ten patients were male and 33 female. Mean age was 66 years. We performed CT scanning using a modified Berger technique. The lower limbs were extended and scans were performed perpendicular to the mechanical axis of the knee from the supracondylar region of the femur to the plane passing under the distal end of the tibial component up to the anterior tibial tuberosity. Reference lines to assess the rotation of each prosthetic component were drawn electronically on the scan planes.

Adding together the rotation values of the prosthetic components, we observed that when total internal rotation was between 10° and 4°, there was subluxation or frank dislocation. When total internal rotation was between 1° and 4° the disorder was not severe, such as patellar tilt. When total internal rotation was less than 1° or when the components were externally rotated, no femorotibial compartment disorders were observed. The modified Berger technique enabled us to correlate the degree of prosthetic internal rotation with the severity of the disorder and further demonstrate the benefits of femoral component external rotation on patellar glide and ligament balance of the prosthesis.

The authors believe that using CT with the helicoidal technique, by modifying Berger’s technique, enables an accurate assessment of prosthetic component rotation, subsequent correlation with femoro-patella symptoms, and adequate pre-operative planning in case of revision surgery.