Summary

Pyogenic spondylodiscitis is an uncommon but severe spinal infection. In majority of cases treatment is based on intravenous antibiotics and rigid brace immobilization. Posterior percutaneous spinal instrumentation is a safe alternative procedure in relieving pain, preventing deformity and neurological compromise.

Pure tantalum has been proposed in orthopaedic surgery. Its chemical and physical properties have been widely studied in the past. From pure tantalum is obtained a spongy structure (Trabecular Metal Technology: TMT) that shows a full thickness porosity which is 2–3 times higher compared to other surfaces available for bone ingrowth with a three-dimensional porous arrangement in rough trabeculae. Pores (average diameter of 650 mm) are fully interconnected and represent 75–80% of the whole volume. TMT acetabular components have an elliptical shape and have an irregular external surface which both allow an optimal mechanical fit.

We retrospectively reviewed 212 cases of monoblock porous tantalum acetabular cup (Hedrocel, Stratec) implanted between 1999 and 2003 in a single centre with a minimum follow-up of 9–10 years; There were 98 men and 114 women, with an average age of 65 years. They all underwent primary or revision total hip arthroplasty or to acetabular component revision alone. In all patients a monoblock porous tantalum acetabular component with polyethylene directly compression molded into cup, with or without peripheral holes for screws, was implanted. In all primary procedures the same femoral stem (Synergy, Smith and Nephew) was implanted.

All patients were evaluated with a clinical examination (Harris Hip Score: HHS) and with standard radiographs of the pelvis preoperatively and 1, 3, 6 months and yearly postoperatively. The stability of the acetabular cup was determined by modified Engh's criteria.

The HHS score improved from 42 preoperatively to 94 after one year; at 13 years follow-up it was 95. The subjective outcome was widely satisfying, with the majority of patients experimenting good functional recovery and return to daily activities. Osteointegration of the acetabular component was present in all X-rays controls at one year after surgery. All post-operative evidence of residual bone loss (geodes, bone defects in revisions and in displasia) were no more radiographically evident after 1 year postoperatively as the host bone quickly filled these gaps. We did not observe osteolysis nor progressive radiolucent lines at the latest follow-up. None of the cups was revised, except 3 cases, revised for infection.

Both clinical and radiographic results are the same or even superior to those of coated implants. Our experience confirms that trabecular metal tantalum cups can avoid the formation of bone-implant interface membrane and consequently can avoid implant loosening. The most important advantages of TMT monoblock cups are: no potential for polyethylene backside wear, prevention of loosening and osteolysis, increased early fixation via friction, improved late biological stability, maximum bone-implant contact. High biocompatibility of porous tantalum and its elastic modulus very close to bone influence positively earlier and wider osteointegration of the implant. Larger series are needed to confirm the positive our preliminary results.

To evaluate the findings of fusion of titanium interbody cages in a sheep lumbar interbody fusion model.

Six sheep underwent lumbar discectomy and fusion at L3-L4 throught transperitoneal approach. An cervical threaded expanding and cylindrical cage packed with bone autografts was placed into intervertebral disc space. The sheeps were killed at 9, 12 and 18 months after surgery. The lumbar spines were excised, trimmed of residual musculature and underwent to plain radiographs and CT scans. The spines were dissected and sectioned using the EXAKT microgrinding device creating parasagittal and coronal sections.

Plain radiographs demonstrated no lucent lines around the implants and no change in disc height. CT scans showed mineralized bone within the cages and bone in growth wit anterior bony bridging outside of the cages. Histologic characterizations indicated the presence of mature lamellar bone with osteonic systems filling the central area of the cage. Bone in growth on the surface of the implant is present near the fenestrations alone. A membrane of fibrous tissue layer is present on the external surface of any cage separating bone from the implant.

Expanding titanium cages have shown mechanical and biological validity to achieve an optimal interbody fusion. Design of the cage showed a decisive role to provide superior endplate-to-endplate contact for unsurpassed strenght and stability and to agree the achievement of the interbody fusion across its fenestrations.

Seven patients who had malignant proximal femoral tumours were selected for resection and limb salvage with a modular megaprosthesis. Histopathological diagnosis confirmed one solitary bone metastasis from renal cell carcinoma, one dedifferentiated chondrosarcoma, two primary non-Hodgkin lymphomas non-responsive to adjuvant chemo- and radiotherapy and three low-grade chondrosarcomas. The mean age at the time of surgery was 53.5 years. Post-operative survival averaged 54.5 months. The mean functional status score was satisfactory. There was no local tumour recurrence or dislocation of the prosthesis. There were one superficial wound infection and one post-surgical haematoma. Care must be taken in selecting patients to for resection of the proximal femur and implantation of modular megaprostheses. We reserve such treatment only for tumours that, because of the histopathological diagnosis and spread, chemotherapy or radiotherapy alone is not enough. Modular megaprosthesis is currently the method of choice in the treatment of malignant proximal femoral tumours. With this implant joint function can be restored after wide resection, too, offering a valid alternative to the bony massive allografts that are characterised by a high rate of complications and failure.

Pain and kyphosis in vertebral body compression fractures (VBCF) impair quality of life. Conservative treatment has been the proposed solution up to now. Kyphoplasty is a new technique that involves the introduction of inflatable bone tamps (IBT) into the vertebral body by a trans-pedicle approach. The purpose of IBT is to restore the original height of the vertebral body while creating a cavity that can be filled with highly viscous methylmethacrylate. We prospectively evaluated the safety and efficacy of kyphoplasty in the treatment of pain related to pathological vertebral body compression fractures resulting from osteoporotic collapse, multiple myeloma, primary malignant tumours (lymphoma) and metastatic cancer. Clinical results show immediate and maintained pain relief in all patients who received this treatment and a more rapid improvement in function. Pain relief may be related to spinal realignment by restoring the weight-bearing on the anterior column and to biological factors such as damage of pain-receptors due to the high temperature of cement polymerisation.

Torsional changes in the lower limbs represent a serious clinical problem. The evaluation of the physiological development of the relationship between femur and tibia in the axial plane is necessary for final assessment.

The authors observed 940 patients aged from 4 to 15 years to identify the most important modifications of torsion of the lower limbs during paediatric age. Clinical examination includes assessment in the standing and supine position and observation of the gait features so that the physiological-pathological borderline can be defined, along with peculiar aspects of single and combined deformities, in order to identify indications for osteotomy.

The types of torsion are classified as: (1) isolated augmentation of femoral anteversion; (2) isolated reduction of femoral anteversion; (3) isolated medial tibial torsion; (4) isolated lateral tibial torsion; and (5) combined torsion (femoral anteversion combined with lateral tibial torsion).

The anatomy and the natural progression of femoral and tibial torsion can be assessed by clinical methods. Radiographic methods such as axial CT views are indicated in cases in which clinical examination does not provide clear information and, in particular, if qualitative and quantitative diagnosis is required in order to establish the therapeutic protocol.

The authors conclude by suggesting that the physiological development of torsion should be followed up to skeletal maturity in order to make a general evaluation and to decide on treatment.

The first proposal of high tibial osteotomy to align a varus knee caused by osteoarthritis was ascribed to Steindler in the 1940. The technique was followed by many surgeons because it re-established the load equilibrium in the medial and lateral compartment, reduced the progression of the osteoarthritis and improved the clinical symptoms.

However, as a result of the quick spread of total knee replacement and unicondylar arthroplasty this corrective operation was forgotten. In recent years osteotomies were resumed for two main reasons: (a) the increased diagnosis of knee osteoarthritis in patients of middle age; and (b) the improvement of the technique and improvement of long-term results.

The authors analysed the literature regarding the main techniques utilised in the correction of the axial and torsional deformities of osteoarthritic knee (linear or cuneiform osteotomies). The results of these various methods are similar. This could be due to the importance of common biological effects (early and late) related to the mechanical effect however it is obtained. In conclusion, the authors suggest that osteotomy must be resumed and applied with revised indications (patients in so-called middle age and unicondylar osteoarthritic knee).

The compressive stiffness of cartilage is primarlly determined by proteoglycan, whereas the tensile properties are determined by collagen fibres. The first alteration in cartilage structure during cartilage degeneration is the decrease in proteoglycan content and increase in interstitial water; consequently, cartilage becomes softer and cartilage stiffness decreases. The pupose of our study was to evaluate arthroscopically the compressive stiffness of cartilage in different areas of living human knee joints. Detection of softening is revealed in vivo by using an indentation instrument (artscan 200). The instrument is composed of a measurement rod joined to the handle; in the distal end of the rod, there is an inclined flat surface with a separate plane –ended cylindrical indenter. During measurement the distal end of the instrument is pressed against the articular surface while the indenter imposes constant deformation on the cartilage. The maximal indenter force, by which the tissue resists the constant deformation, is measured with strain gauge transducers. We performed indenter tests in knees joints in which cartilage was diagnosed as normal; stiffness of articular cartilage was also measured during arthroscopy in knees before ACL reconstruction, in knees with closed chondromalacia (ICRS grade 0–1) and in osteochondral lesions (ICRS OCD grade 1) and the data compared with areas of normal cartilage.

As the digital venous system in foetus has received little attention by researchers, a morphological study regarding appearance, localisation and differentation in the foetal hand during the first 3-month period of pregnancy has been conducted. Eighteen fingers from six human embryonic hands of 6, 9 and 12 weeks of gestation, derived from voluntary abortions, were the object of this study. Transverse sections obtained from the tip of the third digit to the base and perpendicular to the digital axis were alternatively stained with haematoxylin-eosin or blue of toluidine. At the sixth week a widespread presence of venous capillary vessels is masked by the mesenchymal cells. At 9 weeks a widespread presence of capillary vessels persists both on the ventral and on the dorsal part of the digit; at this stage it is possible see lacunar areas dividing the finger into compartments. At 12 weeks the neurovascular bundles are perfectly differentiated; in the anterior part there is a widespread presence of capillary vessels and in the posterior part, close to the extensor apparatus, we still see a wide venous area semicircular in shape, going from the apex of the finger till its base.

At the end of the first 3 months of intrauterine life the digital venous system is in its basic pattern already perfectly differentiated. It is possible to describe in the anterior digital part the presence of the superficial and deep venous system. In contrast, in the dorsal part we still see a wide venous lacunar area close to the extensor tendons.

The Q angle is defined as the angle formed by a line passing from the anterior-superior iliac spine and the centre of the patella and another line passing this point to the centre of the tibial tuberosity. Normal values reported in the literature for the Q angle widely range between 12.7° (± 0.72°) and 18.8° (± 4.7°). This variability depends on individual anatomical variations and method of measurement as well. In fact, several factors can affect the measurement of Q angle. The correct evaluation is carried out with a goniometer, in supine position and the knee in full extension. Q angle evaluation can be biased by standing position and quadriceps contraction, which can increase the Q angle; in contrast, knee flexion can reduce it. Furthermore, it has been demonstrated that the Q angle increases from external to internal rotation of the tibia, while it decreases from pronation to supination of the foot. Finally, patellar malalignment in the horizontal plane, such as subluxation or dislocation, causes a decrease in the Q angle, as the centre of the patella is laterally shifted. The accuracy of Q angle measurement can be also affected by an error in identifying the anatomical landmarks. An error in Q angle measurement below 5° requires an error in setting the anatomical landmarks of no greater than 2 mm. Several authors have shown that the Q angle is greater in females, as the proximal landmarks are more lateral and a greater valgus alignment is necessary to reestablish a correct mechanical axis of the limb. According to the side, there is no evidence that Q angle is symmetric.

The clinical significance of the Q angle is controversial. An increased Q angle was considered for a long time as the main cause of anterior knee pain and an important risk factor for patella subluxation or dislocation. Some authors showed a correlation between Q angle increase and symptomatic patellar chondromalacia. However, others showed no significant differences in Q angle values between symptomatic and asymptomatic patients. Presently, there is not sufficient clinical evidence that an increased Q angle predisposes to knee problems. Furthermore, it is impossible to assert that all the alterations of the extensor mechanism are exclusively due to an increase in the Q angle, as they can depend on other factors, such as: functional overloading of the knee, muscle and ligament insufficiency, bone and chondral morphological changes, malalignment or asymmetric length of the inferior limbs and foot alterations.

In conclusion, a homogeneous method of measurement and correct data interpretation are necessary to clarify the conundrum of Q angle. Moreover, it is important to understand that patellofemoral malalignment is not always the cause of knee pain and instability. This can reduce the risk of performing surgical procedures of extensor mechanism realignment that are technically perfect but potentially harmful.