Background: High doses of local antibiotics are used to treat infected acute fractures or chronic osteomyelitis. In the U.S.A., tobramycin is one of the most commonly used antibiotics in trauma surgery. It is an aminoglycoside antibiotic with a broad spectrum of action. However, its effect on the osteogenic potential of bone marrow derived mesenchymal stem cells (MSC’s) is unknown. We hypothesised that high concentrations of tobramycin would be detrimental to the osteogenic potential of multipotent stem cells derived from the bone marrow.

Methods: MSC’s were derived in vitro from reamings obtained in patients undergoing hip hemiarthroplasties. Following subculture, these cells were exposed to various concentrations of tobramycin for 15 days, with a change of media every other day.

The amount of bone formed under each condition was assessed by solubilising the mineral content in hydrochloric acid overnight and then measuring the change in colour induced by Calcium exposed to a commercial reagent. The amount of calcium detected was then determined using a standard curve.

This experiment was repeated in cells from 3 patients.

Results: The amount of calcium formed was as follows Tobramycin concentration of 0 microg/ml

There was a statistically significant impairment in osteogenesis at a concentration of tobramycin of 400 microg/ml and above.

Conclusion: A high local dose of tobramycin affects negatively the osteogenic potential of stem cells derived from the bone marrow.

Introduction: Elderly patients with neck of femur fracture have a wide range of cognition when admitted to hospital. Following hemiarthroplasty, these patients are usually given a standard set of precautionary advice in order to prevent dislocation of their prostheses. This may constitute a loss of time and resources as patients may not recall all the advice given.

Aim: We aim to determine the relationship between mental state on admission and the ability to recollect these precautions postoperatively.

Setting: Leicester Royal Infirmary, a busy teaching hospital

Method: Over a one-month period, 26 patients, aged 70 years and above admitted with hip fracture, were recruited prospectively for this audit study. The patients’ mini-mental test score on admission was used to classify nonaphasic subjects into three groups: normal, mildly impaired and severely impaired cognition. On the 2^nd post-operative day (POD) the patients were given verbal instructions aimed at preventing dislocation of their hemiarthroplasty. Recollection of these precautions was then tested using a specially designed questionnaire (score: 1–10) on POD-6 and at 6 weeks.

Results: One patient died (3.8%). Of the remainder, 21 (84%) were female and 4 (16%) were male. The mean age was 80.4. There were 10 patients in Group-I (normal; 40%), 7 in Group-II (mildly impaired; 28%) and 8 in Group-III (severely impaired; 32%). The resulting score to the questionnaire in Group-I was 6.2 and 3.2; Group-II was 3.3 and 1.2; and Group-III was 0.3 and 0.3 on POD-6 and 6 weeks respectively.

Conclusion: 6 days following surgery, the best recollection of advice is only 2 thirds of what the patient had been told. 6 weeks following surgery, the best recollection of advice is only 1 third of the advice given. The recollection of advice in both mentally impaired groups was very poor throughout the study period. We recommend either not giving hip precautions advice to these patients or changing the way the advice is given to try to improve their recollection.

The longevity of cemented femoral components has been shown to be related to the cement used. The reason for this difference between the available commercial preparations is unclear. One mode of failure of the stem is thought to be cracking within the cement mantle. This may be secondary to residual stress resulting from shrinkage of the cement on curing. It was hypothesised that there was a difference in shrinkage on curing between the different polymethylmethacrylate cements used commonly in hip arthroplasty.

Under standardised conditions, a fixed volume of Palacos-R, Palacos-LV, Simplex, CMW1 Radio-opaque, CMW2 and CMW Endurance was mixed under vacuum and allowed to cure in a measuring cylinder of fixed volume. The cylinder was then split open 24 hours later and the block of cement removed. The final volume of cement was then determined by measuring the volume it occupied in a container filled with water using Archimedes principle.

Our results indicate that, under standardised conditions, the degree of shrinkage for each commercial preparation was Palacos-R 6.9%, CMW1 5.2%, CMW2 5.4%, CMW Endurance 5.3%, Simplex 5.8% and Palacos-LV 7.2%.

There is a difference in the amount of shrinkage on curing between the different types of bone cements in use commercially and this may account for their differences in long term outcome.

Objective: Elderly patients with femoral neck fracture have varying degrees of cognitive capabilities when admitted to hospital. Following hemiarthroplasty, these patients are given standard precautionary advice in order to prevent dislocation of their prostheses. We aim to determine the relationship between mental state on admission and the ability to recollect these precautions postoperatively.

Design: Over a one-month period, 26 patients, aged 70 years and above admitted with hip fracture, were recruited prospectively for this audit study. Mini-mental test score on admission was used to classify non aphasic subjects into three groups: normal, mildly impaired and severely impaired. On the 2^nd post-operative day (POD) the patients were given verbal instructions aimed at preventing dislocation of their hemiarthroplasty. Recollection of these precautions was then tested using a specially designed questionnaire (score: 1–10) on POD-6 and at 6 weeks.

Results: One patient died (3.8%). Of the remainder, 21 (84%) were female and 4 (16%) were male. The mean age was 80.4. There were 10 patients in Group-I (normal; 40%), 7 in Group-II (mildly impaired; 28%) and 8 in Group-III (severely impaired; 32%). The resulting score to the questionnaire in Group-I was 6.2 and 3.2; Group-II was 3.3 and 1.2; and Group-III was 0.3 and 0.3 on POD-6 and 6 weeks respectively.

Conclusion: 6 days following surgery, the best recollection of advice is only 2 thirds of what the patient had been told and 6 weeks following surgery, the best recollection of advice is only 1 third of the advice given. The recollection of advice in both mentally impaired groups was very poor throughout the study period. We recommend either not giving hip precautions advice to these patients or changing the way the advice is given to try to improve their recollection.

Implantation of allograft bone continues to be an integral part of revision hip surgery. One major concern with its use is the risk of transmission of infective agents. There are a number of methods of processing bone in order to reduce that risk. One part of that processing can be carried out immediately prior to implantation using pulsed irrigation.

We report the incidence of deep bacterial infection in a series of 138 patients undergoing 144 revision hip arthroplasty procedures who had undergone allograft bone implantation. The allograft bone used was fresh-frozen non-irradiated. Allograft femoral heads were milled following removal of any residual soft tissue and sclerotic subchondral bone. The bone chips were then placed in a standard metal sieve and irrigated with Normal Saline (pre-warmed to 60 degrees Centigrade) delivered as pulsed lavage at 7 bar pressure. No antibiotics were used in the irrigation solution. The bone chips were washed until all visible blood and marrow products had been removed.

The deep infection rate at a minimum one year follow-up was 0.6%. This method of secondary processing appears to be consistent with a very low risk of allograft related bacterial infection.