Franz Burny

We designed a sensor that measures the bending moments at the articulations and the torque of the rod of a Hoffmann II® external fixation. We considered the effect of the callus formation in the stabilisation of a “fracture-fixation system.”

On the occasion of the thirty years since its inauguration, the Department of Orthopaedics and Traumatology of the University Hospital Erasme reviews the milestones of its development. Various original new techniques have been implemented: monitoring of implants using strain gauges, external fixation of the limbs, external minifixation, miniinvasive anterior approach in hip arthroplasty, knee ligamentoplasties, orthopaedic microsurgery and composite tissue allotransplantation. The care of aged patients takes place in close collaboration with the Department of Geriatrics. Two new clinical units have been created, the Unit of Hand and Peripheral Nerve Surgery, and the Centre for Sports. The Department has organized an efficient Bone Bank. The new day care hospital improves the possibilities of ambulatory surgery. The article details as well the activities of teaching and research of the members of the Department.

The history of the Orthopaedics and Traumatology Research Laboratory (LROT) is summarized during the last thirty years. The approach, initially focused on bone biomechanics and strength of materials, underwent a rapid diversification as expressed by the list of research topics: monitoring of bone healing; bone strains measurements for different level of activities including microgravity and prevention of disuse osteoporosis; biological effects of electromagnetic fields; evolution of the viscoelastic properties of the callus during bone healing; improvement of the osteoinductive properties of bone substitutes produced by the Tissues Bank of the University Hospital Erasme; Kashin-Beck disease; SICOT telediagnostic, and biomechanics of threaded implants. Those topics, event the most fundamental ones, have immediate significant clinical applications allowing a decrease of the morbidity and an acceleration of the rehabilitation of the patients. The results show the need of multidisciplinary collaborations coordinated around one autonomous laboratory, able to handle specific protocols requiring a dedicate environment.

Distraction radio-metacarpal external fixation is an excellent technique for the osteosynthesis of distal radius fractures, in particular of comminuted articular fractures. The alternative is the locked palmar plate, a more demanding technique. The published literature does not allow concluding if one method is better than the other. The other main possible indications of external fixation at the wrist are comminuted fractures of the base of the thumb metacarpal, distal radius osteotomies, and wrist arthrodeses. At the hand, external minifixation is an excellent technique of osteosynthesis. Stable bone fixation is obtained, allowing early active mobilization of the fingers. The technique is especially indicated to treat open lesions or to perform lengthening, but we use also external minifixation to treat closed fractures, to perform arthrodesis or to cure non-unions, and to maintain the length of the thumb after trapeziectomy for osteoarthrosis.

The authors present a prospective study on the potential correlations between eight footprint parameters and three radiological parameters in the study of the plantar arch. Seventy nine patients were evaluated in 2001. The eight footprint parameters were as fellows : the arch angle, the Chippaux-Smirak's index, the Quamra's contact index 2,3 and 4, the Schwartz's footprint angle, the Staheli's arch index and the arch length index. The three radiological parameters were as fellows : the Djian-Annonier's angle, the Méary's angle and the calcaneal inclination. This prospective study confirms the best correlation, found in others studies, obtained between the Djian-Annonier's angle and the Chippaux-Smirak. The use of the Méary's angle and the calcaneal inclination is not justified because they have bad correlations with footprint parameters.

The classical plaster bandage was devised in the mid 19th century. Until recently, osteoarticular trauma has been treated mostly by plaster cast immobilisation using plaster of Paris. Synthetic materials have been introduced on the market place in the seventies, but they have not superseded the traditional plaster of Paris. The more recent thermoplastic materials are used to make splints and orthoses, particularly at the wrist and hand. The present review of the literature confirms that synthetic materials present better physical and mechanical properties than the traditional plaster of Paris. In addition, they are lighter, they are more resistant to humidity, they are more radiotransparent and they generate less dust when removed. However, they are less malleable and cause higher pressure in case of limb edema. Plaster of Paris therefore remains indicated in the acute posttraumatic or postoperative period. This material is also cheaper, but the pecuniary benefit is limited for several reasons, particularly because plaster of Paris is associated with a higher rate of cast replacement.

The Department is involved in clinical and research activities. We pioneered the clinical application of "smart of Orthopaedic implants". The monitoring concept, bringing a high added value, helps in assessing fracture healing or implant fixation. The technique, featuring the 21st century, also requires advanced knowledge in biomaterials. Such implants have been used during the ESA Parabolic Flight Campaigns. These measurements are a prerequisite to establish prevention programs of the bone demineralisation during space flights but also in disuse osteoporosis. The Department is deeply involved in external fixation. In vitro studies of the mechanical insertion and holding parameters of external fixation pins have been performed to produce new implants, which efficiency has been proved by a clinical study. We defined original clinical principles of external fixation as its use in upper limb indications, to maintain microsurgery transplant, preserving devascularization and providing adequate fixation. Our biomechanical approach of the upper limb, now confirmed by others research groups, questioned old clinical concepts. The isokinetic evaluation assesses the dynamic function of articulations, i.e. after arthroplasty, and is also used for medico-legal evaluation. The clinical research touches orthopaedic (or systemic) diseases as algodystrophy, Kienböck disease, Kashing Beck. We conducted a multidisciplinary research on the effect of electromagnetic fields (EMF) on cells differentiation. In addition to possible healing properties, it helps as an objective support to analyse the exposure to the environmental EMF.

The authors present the technique and clinical results of a corrective osteotomy for malunion following extra-articular fractures of the distal radius. External fixation allows restoration of the length of the radius with minimal damage to the periosteum. It allows early mobilization of the radiocarpal joint. The position of the distal pins provides intraoperative visual control of the angular correction. The minimal invasive approach decreases the risk of iatrogenic lesion of an extensor tendon or a sensitive branch of the radial nerve. This technique is easy and reliable.

Extensive clinical experience has been built up using orthopaedic implants instrumented with strain gauges connected to a Wheatstone bridge by means of percutaneous leads. This research showed the medical relevance of the monitoring of the deformation of implants as a powerful tool to evaluate nursing and rehabilitation exercises, for tracing dangerous overloads and anticipating implant failure and also to observe the healing process. The IMPACT 3500 project focuses on the instrumentation of femoral implants with on board sensors: regular Benoist-Girard implants have been modified, to contain a 'sensing cell', and thoroughly tested in vitro and in vivo. The implant deformations are measured with resistive strain gauges, and the signal is transferred to a personal computer for processing and display, via a hard wired connection, or via a telemetry system. Two fully implantable wireless designs, called Linkstrain and Sealstrain, are powered from the outside by magnetic induction. As Sealstrain contains the whole telemetric system in its cavity, the highest miniaturization was required; this seriously deteriorates the efficiency of the inductive power link.

The fractures of the hand are frequent and represent a problem of public health. The displacement of the fracture occurs because of post-traumatic musculo-tendinous imbalance. The fractures of the hand are to be treated according to four principles: anatomical reduction, followed, when possible, by immediate mobilization, if necessary, by immobilization of the injured parts in the "protective" position (metacarpophalangeal flexion, interphalangeal extension and with the first web space under stretch), and prevention of post-traumatic edema. When an osteosynthesis is performed, the mounting should be stable enough to allow early mobilization. The most useful techniques include external minifixation, and internal fixation using one or several screws.