The use of navigation to achieve soft tissue balance in total knee arthroplasty - a randomised clinical study.

BACKGROUND: Achieving soft tissue balance is an operative goal in total knee arthroplasty. This randomised, prospective study compared computer navigation to conventional techniques in achieving soft tissue balance. METHODS: Forty one consecutive knee arthroplasties were randomised to either a non-navigated or navigated group. In the non-navigated group, balancing was carried out using surgeon judgement. In the navigated group, balancing was carried out using navigation software. In both groups, the navigation software was used as a measuring tool. RESULTS: Balancing of the mediolateral extension gap was superior in the navigation group (p=0.001). No significant difference was found between the two groups in balancing the mediolateral flexion gap or in achieving equal flexion and extension gaps. CONCLUSIONS: Computer navigation offered little advantage over experienced surgeon judgement in achieving soft tissue balance in knee replacement. However, the method employed in the navigated group did provide a reproducible and objective assessment of flexion and extension gaps and may therefore benefit surgeons in training. LEVEL OF EVIDENCE: Level I, RCT.

Poor results of the Freeman uncemented metal-backed acetabular component. Five-to-nine-year results.

We reviewed 120 consecutive primary total hip replacements in 109 patients in whom a Freeman uncemented metal-backed component had been used. Acetabular components were used with a Freeman neck-retaining stem in one of three configurations: cemented smooth stem, uncemented smooth stem or uncemented ridged stem. After a mean follow up of 72 months (62 to 113) there were nine cases of aseptic loosening; a survivorship at eight years of 83%. In addition, more than one-third of the remaining surviving cups showed loosening radiologically. The Freeman acetabular component demonstrated a characteristic pattern of loosening on radiographs. The high incidence of aseptic loosening can be explained by poor design and material failure.

The medium-term results of a cemented Freeman femoral neck-retaining prosthesis.

We have reviewed 202 consecutive primary hip replacements using a Freeman cemented femoral component after a mean period of follow-up of 64 months (23 to 113). There was only one revision for aseptic loosening. Retention of the femoral neck may act to reduce the torsional and shear forces at the implant-cement interface and may provide a seal against the migration of polyethylene-laden joint fluid in the potential joint space. The cemented Freeman femoral component with retention of the femoral neck was successful for up to nine years.

Avulsion of the tibial tuberosity in a litter of greyhound puppies.

Avulsion of the tibial tuberosity was diagnosed in six of seven greyhound littermates aged five and a half months. The puppies showed hindlimb lameness of varying severity. Radiological assessment of affected stifle joints revealed partial or complete avulsion of the tibial tuberosities. In four puppies the lesions were bilateral. Euthanasia of the two most severely affected puppies was performed; the changes observed on histopathological examination of their cranioproximal tibiae suggested that the underlying lesion was that of osteochondrosis. A hereditary predisposition in greyhounds to osteochondrosis of the physis between the apophysis and the cranioproximal tibial diaphysis is postulated.

Early radiological observations may predict the long-term survival of femoral hip prostheses.

We reviewed a consecutive series of 527 uninfected hip replacements in patients resident in the UK which had been implanted from 1981 to 1993. All had the same basic design of femoral prosthesis, but four fixation techniques had been used: two press-fit, one HA-coated and one cemented. Review and radiography were planned prospectively. For assessment the components were retrospectively placed into two groups: those which had failed from two years onwards by aseptic femoral loosening and those in which the femoral component had survived without revision or recommendation for revision. All available radiographs in both groups were measured to determine vertical migration and examined by two observers to agree the presence of radiolucent lines (RLLs), lytic lesions, resorption of the neck, proximal osteopenia and distal intramedullary and distal subperiosteal formation of new bone. We then related the presence or absence of these features and the rate of migration at two years to the outcome with regard to aseptic loosening and determined the predictive value of each of these variables. Migration of > or = 2 mm at two years, the presence of an RLL of 2 mm occupying one-third of any one zone, and subperiosteal formation of new bone at the tip of the stem were predictors of aseptic loosening after two years. There were too few lytic lesions to assess at two years, but at five years a lytic lesion > or = 2 mm also predicted failure. We discuss the use of these variables as predictors of femoral aseptic loosening for groups of hips and for individual hips. We conclude that if a group of about 50 total hip replacements, perhaps with a new design of femoral stem, were studied in this way at two years, a mean migration of < 0.4 mm and an incidence of < 10% of RLLs of 2 mm in any one zone would predict 95% survival at ten years. For an individual prosthesis, migration of < 2 mm and the absence of an RLL of < or = 2 mm at two years predict a 6% chance of revision over approximately ten years. If either 2 mm of migration or an RLL of 2 mm is present, the chances of revision rise to 27%, and if both radiological signs are present they are 50%. If at five years a lytic lesion has developed, whatever the situation at two years, there is approximately a 50% chance of failure in the following five years. Our findings suggest that replacements using a limited number of any new design of femoral prosthesis should be screened radiologically at two years before they are generally introduced. We also suggest that radiographs of individual patients at two years and perhaps at five years should be studied to help to decide whether or not the patient should remain under close review or be discharged from specialist follow-up.

Filaroides hirthi verminous pneumonia in a West Highland white terrier bred in Ireland.

A two-year-old West Highland white terrier, which had failed to thrive from six months of age, presented with acute onset dyspnoea. Radiography showed a diffuse pulmonary infiltrate throughout both lungs. Haematological abnormalities were an absolute neutrophilia and eosinophilia. Postmortem examination revealed uniform consolidation of both lungs which was defined histologically as a verminous granulomatous pneumonia. Metastrongyle larvae, isolated from the pulmonary tissue, had the morphological characteristics of Filaroides species. On the basis of the pathological changes and the larval morphology, a presumptive diagnosis of F hirthi pneumonia was made. This is believed to be the first report of disease due to this parasite in Ireland.

Radiological and survival comparison of four methods of fixation of a proximal femoral stem.

We compared the radiological appearances and survival of four methods of fixation of a femoral stem in 538 hips after follow-up for five or ten years. The fixation groups were: 1) press-fit shot-blasted smooth Ti-A1-V stem; 2) press-fit shot-blasted proximally ridged stem; 3) proximal hydroxyapatite (HA) coating; and 4) cementing. Survival analysis at five to ten years showed better results in the HA-coated (100% at five to six years) and cemented stems (100% at 5 to 6 years) than in the two press-fit groups. There was a higher mean rate of migration in the smooth and ridged Ti-A1-V shot-blasted press-fit groups (0.8 mm/year and 0.6 mm/year, respectively) when compared with the HA-coated and cemented prostheses (both 0.3 mm/year). More radiolucent lines and osteolytic lesions were seen in the press-fit groups than in either the HA-coated or cemented implants, with a trend for a lower incidence of both in the HA compared with the cemented group. Proximal osteopenia increased in the press-fit and cemented prostheses with time, but did not do so in the HA group. There was a higher incidence of resorption of the femoral neck with time in the cemented group than in the other three. We conclude that the HA and the cemented interfaces both provide secure fixation with a trend in favour of HA. The cemented prosthesis meets the suggested National Institutes of Health definition of 'efficacious' at ten years.

Morphometric analysis of growth retardation in fetal lambs following experimental infection of pregnant ewes with border disease virus.

The onset of growth retardation was investigated in fetal lambs following experimental infection of pregnant ewes with Border Disease virus (BDV) on day 53 of pregnancy. Fetuses from control and infected ewes were harvested at weekly intervals between day 60 and day 95 of gestation and morphometric studies were completed on tibial radiographs and tibial growth cartilage metaphyseal junctions. Mean tibial areas were significantly reduced (P < 0.01) in fetuses from infected ewes at 35 and 42 days after infection and growth cartilage metaphyseal junctions were less mature in fetuses from infected ewes at 42 days after infection. Positive immunostaining for BDV antigen was demonstrated in the brains of all fetuses from infected ewes between 14 and 42 days after infection. Attempts to demonstrate BDV antigen in bone proved unsuccessful. It is concluded that intrauterine growth retardation is an early manifestation of BDV infection in lambs and that the process is initiated shortly following infection of the fetus.

Taking suffering seriously: a new role for the medical case history.

The relief of suffering is commonly cited as a principal goal of clinical medicine. Yet suffering receives little attention in medical case histories, except for symptoms of pain or dysfunction that are useful diagnostically or in following the course of known disease and evaluating the effects of treatment. Contemporary attempts to deal more formally with suffering--the patient's personal experience of sickness or disability--by recording that information in case histories and medical records began with the problem-oriented medical record and continue with various proposals to include the "patient's perspective" or the "patient's review" in case presentations or records of medical care. Medicine's commitment to the relief of suffering is a compelling warrant to make the identification of the patient's perspective a major goal of historical inquiry and representation, beginning with a "history of present illness" that describes the patient's sickness or disability from two perspectives: that of the disease (a biomedically oriented account of the patient's sickness) and that of the illness (a description of the patient's personal situation, sufferings, perplexities, hopes, and fears). Experience with an earlier version of this reform suggests that optimal understanding and implementation of such a dual-perspective history by students and their instructors requires concomitant study of such matters as the goals of clinical medicine and the nature of suffering.

From principles to principals: the new direction in medical ethics.

Many alternatives or supplements to "principalism" seek to reconnect medical ethics with the thoughts, feelings, and motivations of the persons directly involved in ethically troublesome situations. This shift of attention, from deeds to doers, from principles to principals, acknowledges the importance of the moral agents involved in the situation-particular practitioners, patients, and families. Taking into account the subjective, lived experience of moral decision-making parallels recent efforts in the teaching of medicine to give the patient's subjectivity-his or her personal experience of being sick or disabled epistemological parity with scientific medicine's "objective," biomedically-oriented view of the person's sickness or disability. Moreover, the shift from principalism to principals signals a growing realization that ethical problems in the profession of medicine are inseparable from its practice. Philosophers and other humanists working in medicine should resist the temptation to institutionalize a professional role as solver of ethical problems, clarifier of values, or mediator of disputes and work instead to help practitioners practice medicine reflectively.

Effect of partially purified Staphylococcus aureus beta-haemolysin on the mammary gland of the mouse.

Partially purified Staphylococcus aureus Beta-haemolysin and a S. aureus strain (FGH28), isolated from a clinical case of bovine mastitis, known to produce in vitro Beta-, but neither Alpha- nor Delta-haemolysins were each injected separately into the mammary gland of mice. Relative purity and in vitro biological activities of this preparation were assessed. The effects of both the partially purified preparation and the S. aureus strain injected were assessed in terms of mortality, clinical appearance, macroscopic and microscopic changes, recovery of organisms from the inoculated glands and biological activity in supernatants from ground mammary glands. When injected alone, partially purified Beta-Haemolysin was not found to be an important virulence factor, being a diffuse infiltration of neutrophils into the alveoli the pathological effect observed following its inoculation. Vascular lesions were observed, in the most severe cases, following injection of S. aureus FGH28.