Summary Statement

Patients with adolescent idiopathic scoliosis show clear signs of abnormal motor coordination between the long superficial paraspinal muscles and the deep rotators. These findings suggest an abnormal behavior of the deep rotator muscles at the concave side.

A recently developed parametric geometrical finite element model (p-FEM) was adapted to the specific hip geometric measurements of a group of patients with slipped capital femoral epiphysis (SCFE). The objective was to analyze the stress distribution in the growth plate of these patients and to evaluate differences for those patients who developed bilateral disease.

Different geometric parameters were measured in the healthy proximal femur of 18 adolescents (mean age, 12,1 yr) with unilateral SCFE and in 23 adolescents matched in age without hip disease (control group). Five patients developed SCFE in the contralateral side during follow-up. Different geometric measurements were taken from hip conventional X-ray studies. The p-FEM of the proximal femur permits modifications of different geometrical parameters, therefore the X-ray measurements taken from each patient were applied to the model obtaining a subject-specific model for each case. In each model, different mechanical situations such as walking, stairs climbing and sitting were simulated by applying loads on the femoral head corresponding to each own weight. The risk for growth plate failure was estimated by the Tresca, von Misses and Rankine stresses.

In summary, the models shows important differences between the stresses computed at the healthy femurs of patients with unilateral SCFE and femurs that further underwent bilateral SCFE. So, the 95% confidence interval of the percentage of volume of the growth plate subjected to stresses higher than 2MPa was almost similar for the control group and patients with unilateral SCFE. However, those patients who developed bilateral disease had statistically significant large physeal areas with more than 2.0 MPa (p< 0.005). Stresses were also strongly dependent on the geometry of the proximal femur, especially on the posterior sloping angle of the physis and the physeal sloping angle.

In spite of simplifications of the developed p-FEM, this tool has been able to show the influence of femur geometry in growth plate stresses and to predict the sites where growth plate starts to fail.

Hip Resurfacing (HR) is nowadays widely used as an alternative to Total Hip Replacement (THR), especially for the young and active patients. Because of the more physiological distribution of the load in the femur, this technique is particularly known to reduce bone loss due to stress shielding behaviour, a major problem encountered with THA. Different computational studies have analysed the performance of HR prostheses. Therefore, the purpose of this study is to apply a computational approach, in fact a bone remodelling analysis, in order to investigate its application to evaluate the bone structure changes postoperatively.

A Finite Element model was developed of a femur with HR prosthesis. The model was reconstructed starting with the femur medical images, and then the prosthesis was positioned in the clinical implantation angle (5° valgus). A cement mantle thickness of 1mm was included. Then a Finite Element Analysis in combination with a bone remodelling model (bone material properties) was performed. The results obtained predict as there is a certain bone loss in the superolateral and inferior medial zone. Additional bone material apposition is locally found with the aim of fixing the implant stem on the medial side, but also a remarkable distal ingrowth around the stem tip. All these findings are in good qualitative agreement with clinical observations.

We conclude that the numerical simulation used in this study is a useful tool in predicting bone remodelling inside a cemented HR prosthesis. This kind of methodologies will help on the design of devices, surgical techniques, etc.

Successful treatment of prosthetic joint infections (PJIs) requires surgical intervention and prolonged antimicrobial therapy (AT), although the most suitable management has not been clearly defined yet. The aim of the study is to review our experience in the management of AHPJIs.

From 01/01/2004 to 31/12/2006 all patients with PJIs were prospectively evaluated in 8 Spanish hospitals by the REIPI. We focused here on AHPJIs. Diagnostic of infection was based on clinical-microbiological evidence.

Forty-nine patients, 30 (61.2%) women, median age: 75.35 years (range: 31–92), were diagnosed of AHPJIs: 22 (44.8%) hips, 26 (53%) knees and 1 (2%) elbow implants. Following total joint replacement our patients had a median infection-free period of 4.9 years (range 0.3 to 18.7). The comorbidities were: 9 (18.3%) rheumatoid arthritis, 7 (14.3%) diabetes, and 6 (12.2%) chronic renal failure. Clinical features were acute in all cases: pain 100%, inflammatory signs 75.5%, and fever 70%. In 27 (55%) of the cases a distant previous infection caused by the same microorganism could be identified. The etiology was: S. aureus 18 (36.7%), streptococcal infections 13 (26.5%), coagulase-negative staphylococci 2 (4%), gram-negative bacilli 11 (22.4%), anaerobes 2 (4%), and mixed infections in 3 (6.1%) cases. Thirty (61.1%) patients underwent early drainage/debridement with retention of the implant, 11 (22.4%) two-stage replacement, 6 (12.5%) arthrodesis, 1 (2.1%) resection arthroplasty, and 1 unknown. Patients were treated with specific AT (median duration of 10.6 weeks) according to the isolated microorganism. At 1 year follow-up 25 (51%) were cured, 7 (14.3%) relapsed after a conservative approach (3 required an arthrodesis and 1 a two-stage replacement), 5 (10.2 %) died and 5 (10.2%) had a re-infection; in 7 the evolution was unknown.

AHPJs can be successfully treated in most cases with surgical debridement plus an antibiotic course. If a relapse is observed, removal of the prostheses could be necessary.

Introduction and purpose: We present a new decision-making method to assist orthopaedists and radiologists in diagnosing soft-tissue tumours. It can distinguish between benign and malignant characteristics in these lesions and classify them histologically with satisfactory efficiency. The pre-surgical diagnosis of the nature of the tumour and whether it is benign or malignant is crucial to planning surgical procedures.

Materials and methods: We reviewed our cases of soft-tissue tumours (47) studied by MRI over the past year and a half. They are part of a multicentre study involving several European hospitals (430 patients).

We analysed the clinical and MRI data: age, clinical presentation, size, shape, location, edges, image signal, calcification, intratumour fat, dependency, fibrosis, relation to fascias, bone and vessel disorders.

Results: With this method we detected 62% benign tumours and 38% malignant. The system sensitivity and specificity are 86% and 95%, respectively.

Conclusions: It is easy to distinguish between vascular, nerve and cystic lesions. The diagnosis of fibrous, synovial and fatty lesions is complex in all cases.

The method can help orthopaedists make a diagnosis before surgery, which will facilitate planning of surgical procedures.

Introduction and Objectives: Osteochondral lesions of the talus are difficult to treat due to difficult access, vascularisation, and because the head of the talus is a region with significant mechanical load. Among the therapeutic options for osteochondral lesions of the head of the talus, we present a treatment alternative using mosaicplasty with an autologous osteochondral graft taken from the knee.

Materials and Methods: We have treated 8 patients affected with osteochondral lesions of the head of the talus (7 medial and 1 lateral) of greater than 7mm diameter, younger than 45 years of age, and with no instability of the ligament. The talus was approached in all cases by means of osteotomy of the malleolus. Osteocartilaginous cores were collected from the ipsilateral lateral condyle of the ipsilateral knee with minimal arthrotomy. Rehabilitation began between days 3 and 5 with no weight bearing before the 6th week. Results were measured by means of CTscan, MRI, and pathology, and clinically using the Maryland scale.

Results: All patients presented with evidence of osteointegration of the osteochondral graft. All were classified as excellent or good on the Maryland scale. Functional results were good with flexion and extension movements of the ankle practically symmetrical with the healthy limb. There were no complications in the donor site or infections. None of the patients has required repeat treatment except in the cases in which material for osteosynthesis was removed from the malleolus.

Discussion and Conclusions: We believe that in view of the results of mosaicplasty with an autologous osteochondral graft taken from the knee, this provides a new therapeutic approach to treatment of grade III and IV osteochondral lesions of the talus. The most significant advantages of this technique include the repair of articular cartilage with type II collagen and an earlier discharge time due to osseous integration. The most important disadvantages were potential morbidity associated with the donor site and the technical difficulty in achieving convexity.

We performed a neurological and radiological study of the wrists of 58 patients with Hansen’s disease and 60 age-matched healthy control subjects. Significant differences (p < 0.01) were found between the groups in the carpal glenoid sector, the radial physeal widening index, the carpal ulnar distance, the carpal index and in distal radio-ulnar discrepancy.

Comparison of the results in three subgroups of leprous patients with sensory impairment (group A-1), motor deficit (A-2) and no neurological impairment (A-3), showed significant differences (p < 0.01) between group A-1 and the other two. This suggests that in these patients the changes in the carpus and radiocarpal joint may be caused by neuropathic arthropathy of the wrist.

Our findings are of particular interest since there are few reports of neuropathic arthropathy in non-weight-bearing joints.