Radiographic evidence of migration of the femoral stem component after THA is the most important diagnostic sign of femoral implant loosening. Early detection of stem subsidence may help in deciding to perform revision surgery before severe bone destruction has occurred, at a moment when standard clinical and radiological follow-up may still be reassuring.

The aim of this study was to identify the most appropriate bone and prosthetic landmarks to study subsidence and to determine the accuracy of the Imagika® method as compared to the ‘gold standard’ EBRA-FCA® software.

256 THA in 242 patients (102 men, 140 women) with a median age of 63.8 years (range: 36–85) received 4 different cementless or cemented prosthetic stem designs. They were followed for 10.6 years (range: 6–16). CLS® stems were used in 56 patients, MS-30® in 76, Elite® in 50 and Osteal® in 74.

4 specific analysis models were created in the Imagika® software in order to evaluate several possible landmarks on the proximal femur and on the stem, and to evaluate the possibility of using a correction factor to improve the comparability of successive x-rays taken under non standardised conditions. The most accurate prosthetic landmarks were the prosthesis shoulder in CLS® and MS-30® stems and the lateral aspect of the collar in Elite® and Osteal® stems. The best bone landmark was the top of the greater trochanter in all cases.

For the whole series, the annual linear subsidence rates were 0.049+/−0.014 mm with EBRA-FCA® and 0.052+/−0.012 mm with Imagika® respectively (P = 9E-7). Migration values in the 4 different groups were respectively 0.06 +/− 0.01 mm/yr and 0.05 +/− 0.01 mm/yr in the CLS® group (P = 4.6E-6), 0.02 +/− 0.002 mm/yr and 0.06 +/− 0.09 mm/yr in the MS-30® group (P = 6.8E-4), 0.06 +/− 0.002 mm/yr and 0.04 +/− 0.003 mm/yr in the Elite® group (P = 4.2E-5), and 0.05 +/− 0.005 mm/yr and 0.06 +/− 0.004 mm/yr in the Osteal® group (P = 7.4E-7). The different prosthetic designs did not show significant differences concerning migration values when studied according both methods.

Thanks to a correction factor, the Imagika® method uses all the radiographs when EBRA-FCA® rejects incomparable radiographs.

The Imagika® method is more users friendly and provides excellent reliability thanks to an automatic edge detection device.

Since no significant difference was observed between EBRA-FCA® and Imagika® methods whatever the prosthetic stem design studied, our results authorise us to apply these analysis models within the Imagika® software to all THAs to follow their radiographic evolution and to possibly predict the clinical evolution.

Bleeding is an inevitable consequence of most surgical interventions. Total blood loss resulting from an operation can be calculated from the observed drop in haemoglobin and haematocrit levels, taking into account the amounts of blood transfused. Total blood loss is partly accounted for by the measurable external blood loss, during operation and in the drains, but there is also occult blood loss in the tissues, which is often as much as or even greater than the measurable external blood loss; occult blood loss is often underestimated; it has been found to represent on average 30% of the total blood loss after THR, and 45 to 60% after TKR.

Blood loss may be important enough to require compensatory measures. Transfusion of homologous blood has been for a long time the method of choice, but its use has been restricted for a number of reasons, among which the fear of viral transmission, although it has decreased dramatically over the past few years.

There are several possible ways to reduce the requirement for allogenic blood transfusion in surgery. They can be distributed under the following headings:

Reduce perioperative blood loss

These topics will be covered by the participants to this symposium, each of whom has been involved in major clinical studies and is a recognised expert on one or several aspects of this blood management strategy.

As we will see, transfusion of homologous blood can be avoided in a high proportion of cases through judicious use of the various possibilities available.

Before any given operation, the first step must be to evaluate the anticipated total blood loss, and to figure out whether this is higher or lower than the allowable blood loss for that specific patient. The allowable blood loss will depend on the preoperative blood volume and haematocrit of that patient, and also on the haematocrit that is to be preserved postoperatively, taking into account specific features of that patient, such as coronary heart disease. If the anticipated blood loss is greater than the allowable blood loss, some form of action is necessary in order to reverse the balance. This can be achieved by reducing blood loss and/or by improving the preoperative haematocrit of the patient, together with either autologous blood predonations – if the patient’s condition permits - and/or re-infusion of recuperated shed blood. Blood substitutes have not yet reached a stage of clinical applications.

The management of blood loss must be given appropriate consideration in all surgical procedures; it requires a customised approach, from the preoperative consultation until the postoperative period.

An informed consent document signed by a patient before surgery is supposed to provide evidence that he effectively received adequate information to be able to give informed consent. In fact, it only provides limited legal protection to the surgeon. Although the situation may vary from one country to another and, within each country, from one court to another, a standard consent form is usually considered inadequate, and a procedure-specific consent form appears as a minimal requirement. Even this will provide limited protection if a patient has presented a complication not listed. When confronted to a determined lawyer who pleads the absence of informed consent, a surgeon will most often not be able to give evidence for disclosure of some specific items to the patient.

This raises a number of questions:

- How extensive should the information be? Should compliance with a legal obligation always prevail over common sense?

In litigation cases, the burden of proof used to bear on the patient but has now more or less overtly been transferred to the surgeon, while he is not offered the possibility to face such demands in the current organisation of health care in most countries. Even though paternalistic medicine is no longer politically accepted, many patients still expect counselling rather than just information; law makers and lawyers have decided that these patients are wrong, but it is difficult for physicians who have been trained in the spirit of Hippocrates’ oath to behave merely as informers and technical care providers.

Medical activity takes place nowadays under ambiguous conditions. There is a politically accepted vision of medicine in which choices and decisions are made by the patients, as it is supposedly possible to bring all of them to a level of knowledge and understanding which makes this possible; when going in the field, things are different, and most patients are still looking for expert counselling in addition to or in lieu of information. As compared to the situation which prevailed a few decades ago, patients are much less ignorant about medicine in general, but the problem is that medicine has progressed far more rapidly than the layman’s medical knowledge.

Besides, a number of studies have shown that retention of information by patients decreases rapidly over time and is fragmentary, with potential benefits from surgery being recalled much better than possible complications. Patients have also been shown to ingenuously deny receiving information despite documented evidence; ingenuous fabrication, i.e. affirmation of an untruth, is also a classical observation

We know all too well that a number of our patients come to surgery without a proper comprehension of their pathology and therapy, and we have to pretend that we are not aware of it, otherwise we would have to deny those patients the benefit of surgery. To change this would require a major involvement not only of the medical profession but also of the almighty health care administrations and of the funds providers

Every surgical act could be considered a criminal offence, were it not for the patient’s consent. The latter formerly used to be considered implicit but it now has to be made explicit, which may include signing an informed consent document. In case of litigation, the surgeon may be required to provide evidence that the patient received full information and was in a position to give informed consent. Every adult individual is supposedly able to understand and to recall technical information on any specific operation; we know how unrealistic this is. The information should be complete, including on complications least likely to occur; it should also be made understandable to the patient. Assuming this would be possible, the surgeon may be requested later on to provide evidence that such information was provided. How to prove this remains an unsolved problem. A stereotyped informed consent document will be no obstacle to a determined lawyer. Unless every patient receives a customised information booklet written with assistance from a lawyer, the surgeon will always have difficulties in providing evidence that the patient was fully informed. Litigation will often end up with patient and surgeon presenting two irreconcilable versions. One of the reasons is poor retention of information by the patient. A number of studies all showed that retention of basic information is poor and falls down to 50 % after one week and 18 % after 6 months; besides, any “unpleasant” information will be selectively forgotten. In countries that do not have a no-fault compensation system, the only way for some patients to obtain compensation for a disability or financial harm following surgery is to sue the surgeon for malpractice. Lawyers have found out that it was easier to plead the absence of informed consent. We have no real possibility to prevent this, and the quest for absolute security would be hopeless and would result in a paranoid behaviour on the part of the surgeons. Judiciary insecurity has become part of our everyday life and we must cope with it; no-fault compensation systems may improve this but only to some extent. It is best to treat only patients with whom a confident relationship appears possible, as we know that they will usually not quite understand what is going on and will anyway forget most of the information provided.

Over the past 100 years, experimental and clinical studies have tried to accelerate fracture healing and to bring ununited fractures to union . Besides advances in surgical management, non-surgical means have been investigated. Mechanical enhancement of fracture healing using controlled micromotion has been used with some success but does not seem to have been applied to nonunions. Electrical stimulation has been found effective in hypertrophic nonunions, but less so in atrophic nonunions and in the presence of a gap; the various devices available have never gained wide acceptance for various reasons. Low-intensity pulsed ultrasound has been found effective to heal non-unions, especially hypertrophic, with a success rate around 85 % . High-energy extracorporeal shock wave therapy (ESWT) has also been found effective in non-union management, but this is still controversial and there is a need for prospective controlled studies. Biological action has also been attempted for a long time. All attempts to stimulate fracture healing using systemic drugs, diet supplementations, vitamins or hormones have been essentially unsuccessful unless when correcting a pre-existing deficiency . More recently, several molecules have demonstrated an osteoinductive capacity in animal studies; human recombinant BMP-2 is currently under investigation in clinical trials. Percutaneous injection of bone marrow into a non-union has also proved of interest, particularly following centrifugation to increase the number of osteoprogenitor cells; current research aims at selecting these cells prior to injection.

To conclude, a number of non-surgical means are currently available which may be of interest to accelerate fracture healing or to heal nonunions. Some are totally non-invasive, others are minimally invasive; early results have been encouraging for several of them, but there is still a need for clinical validation using prospective controlled studies. Some of those methods may well turn into alternate solutions to surgery in the future . Cost is currently a limiting factor, as long as it is not reimbursed by national health systems in most countries.

Aims: Most mobile-bearing knee prostheses feature bearing rotation; the benefit of also providing AP translation remains controversial. We have compared the kinematic behaviour of the CERAGYR mobile-bearing knee with two different polyethylene bearings, one with a pin-on-hole mechanism allowing only rotation, the other with a pin-on-slot also allowing 5 mm AP translation of the bearing. Methods: A computer-aided study was made on lateral knee X-rays in extension and in 90° flexion, 12 to 36 months following arthroplasty. 30 knees in each group were studied under non-weight bearing conditions (NWB) and 16 under weight-bearing conditions (WB) during a stepup test. Bearing mobility was calculated based on measured displacements between landmarks on the tibial baseplate and in the PE bearing. Results: No AP translation was noted during flexion in the pin-on-hole group; posterior translation of the base-plate during flexion was noted in the pin-on-slot group (mean values: 1.66 mm NWB, 1.37 mm WB). Bearing rotation during flexion was greater in the pin-on-slot group than in the pin-on-hole group (mean values: 6.5° vs 4.4° WB; 3.8°vs 3.3° NWB). A screw home mechanism was noted in 14/16 knees under weight-bearing conditions in the pin-on-hole group, and in 7/16 in the pin-on-slot group. Clinical evaluation showed no difference in outcome between the two groups. Conclusions: Based on these findings, the kinematics of the CERA-GYR knee prosthesis with a pin-on-hole mobile bearing appear closer to normal than with a pin-on-slot bearing, as the latter was found to exhibit reverse femoral rollback as well as reverse screw home in the majority of cases.

Condylar knee prostheses were designed over 25 years ago, as it became evident that the hinge prostheses previously developed were unsatisfactory because of their marked potential for loosening and femoropatellar problems.

There are currently several hundreds of different types and subtypes of condylar prostheses available and more are being introduced on the market place every year. Continuous technical development has become a familiar feature with high technology products; does this also apply to knee prostheses?

The basic designs of condylar knee prostheses already existed 25 to 30 years ago, with the Freeman-Samuelson knee implanted in 1970, the Total Condylar in 1974 and the Insall-Burstein posterior stabilized knee in 1978. Long term results are now available for these prostheses as well as for others that came next: overall, survival rates between 84% and 98% have been reported with follow-up from 10 to 25 years. Will newer implants do any better? It will take that long to know, as it has been repeatedly demonstrated that theoretical studies or tests on knee simulators are not really predictive of the in vivo behavior of an implant.

The wide variety of current implants evidently reflects commercial interests. Each of the current prosthetic knees represents a more or less unique combination of a number of features related to the geometry of the articulating surfaces, including the trochlea and patella, the resection, preservation or substitution of the posterior cruciate ligament, the type of fixation to bone; most have a modular fixed tibial bearing, with various types of fixation to the underlying metal baseplate, and an increasing number of others have a mobile bearing with restrained or unrestrained mobility in rotation and/or in AP translation. The introduction of new knee prosthesis should hopefully provide some improvement in terms of function, range of motion, and implant survival as compared with the existing knees. Such improvements have proved very difficult to demonstrate on an objective basis, all the more as the results achieved with a specific implant do not only reflect its design, but also a number of manufacturing and processing features, and also the way it has been implanted.

We have learned a number of lessons from past failures such as

- the importance of selecting adequate materials

Surgical technique has substantially improved over the years, not only because better instrumentations have been developed, but also because we have come to a better understanding of the anatomy and physiology of the arthritic knee before and after arthroplasty.

The rotational positioning of the femoral component has been extensively studied, and is now a regular feature of the operative technique. This, together with other technical factors such as improved design of the prosthetic trochlea, has to a large extent cleared the femoro-patellar complications which marred the results of some early designs. Techniques for ligament balancing in the varus or valgus knee have become systematized.

The issue of preservation or substitution of the posterior cruciate ligament is still a matter for debate, but we now know that it is unrealistic to expect restoring normal knee kinematics with prosthesis when both cruciate ligaments are not intact. Posterior stabilized prostheses have been shown to provide more predictable kinematics than others intended to be closer to normal physiology.

To summarize, advances have been made over the past 30 years regarding a number of elements among which implant design was probably of lesser importance than better understanding of the anatomy and physiology of the knee, better understanding of ligament balancing and operative technique in general, as well as improved manufacturing and processing of implants.