Aim

Identifying the optimal agent for irrigation for periprosthetic joint infection remains challenging as there is limited data. The ideal solution should have minimal cytotoxicity while maintaining bactericidal activity. We developed a novel activated-zinc solution containing zinc-chloride (ZnCl₂) and sodium-chlorite (NaClO₂). The purpose of this study was 1.) to investigate the antimicrobial efficacy of 2 concentrations (“CZ1”, “CZ2”) against Staphylococcus aureus and Pseudomonas aeruginosa and 2.) to evaluate untoward effects of the solution on local wound tissue 24 hours after solution exposure in pig wound models.

Introduction and Objective

The continued effectiveness of antibiotic loaded bone cements is threatened by antibiotic resistance. The common antiseptic, chlorhexidine (CHX), is a potential alternative to antibiotics in bone cements, but conventional salts are highly soluble, causing burst release and rapid decline to subinhibitory local CHX concentrations. Here, chlorhexidine triphosphate (CHX-TP), a low solubility CHX salt, is investigated as an alternative antimicrobial in PMMA bone cements. The aim was to assess duration of antimicrobial release and antimicrobial efficacy, along with handling, setting and mechanical properties of CHX-TP loaded cements, compared with an existing cement formulation containing gentamicin.

We report the largest multicentre series analysing the use of bone scans investigating painful post-operative Total Knee Replacements (TKR). We questioned the usefulness of reported scintigraphic abnormalities, and how often this changed subsequent management. 127 three-phase bone-scans were performed during a two-year period. Early and late flow phases were objectively classified. Reported incidences of infection and loosening were determined. Reports were subjectively summarised and objectively analysed to establish the usefulness of this investigation. Eight cases were excluded.

Scans were classified as: 33% (39) normal, 53% (63) as possibly abnormal, 6% (7) probably abnormal, and 8% (10) as definitely abnormal. Thirteen patients (11%) underwent revision TKR surgery. Intra-operative analysis revealed loosening of one femoral component, and massive metallosis of the patella in another. Cultures were negative in all cases. The sensitivity and specificity of a definitely abnormal investigation in predicting need for revision surgery was 23% and 82% (respectively). High instances of ambiguously reported abnormalities were observed.

This investigation has no role to play in the routine investigation of a painful TKR. It is unnecessary in investigation of periprosthetic infection and should not be used in a routine assessment of a painful TKR. If used it should be limited until an experienced revision surgeon has made a full assessment.

Sledging related minor and major injuries represent a significant workload at ski-area medical centers across the world. Although safety rules exist, they are seldom obeyed or enforced. We set out to determine the incidence of sledging related injuries, identifying trends and causative factors at a busy New Zealand Ski resort.

All sledging related injuries presenting during a 70-day period were prospectively reviewed. Patient demographics, mechanism, diagnosis, and treatment were recorded. Sixty patients were identified, mean age 10 years, range 4-30 years. Injuries comprised; collisions with sledgers (21), collision with wall (14) and falling from sledge (14). Site of injury included head (36), lower limb (18), spine (9), upper limb (7), and abdomen (2). Fractures included; femur (1), tibia (1), fibula (1), ankle (2), cuboid (1), clavicle (2), scaphoid (1). One 9-year-old patient sustained a serious intracranial haemorrhage, with subsequent permanent neurological sequelae.

Sledging related injuries are mostly minor, however significant major injuries do occur requiring intervention at a secondary center. The potential for serious morbidity is evident. Recommendations supporting safety improvement measures does exist, however most were not implemented by the study cohort examined. The use of basic cycling helmets would seem an appropriate minimum level of protection, and greater sledging safety awareness should be encouraged.

Brace correction based upon mechanical action requires appropriate interface pressure between the body and the brace.

A smart orthotic was developed to record how much time (quantity) a brace was used, how well (quality) it was used and maintain the interface pressure to the prescribed level. Six subjects were recruited and they all used Boston style braces. Each subject used the system for two weeks without the force maintenance system activated to serve as the control period, and the remaining two weeks with the force maintenance system activated. During the automatic feedback mode, the pressure maintenance system was activated only during the daytime (8:00–22:00hrs) to avoid disturbing the patients during sleep. The subject could either return the system to us after one month or continue to use the system until the next clinic.

The time that the pressure level was in the target level range during the study period was increased from 53 +/− 9% to 68 +/− 14% with the feedback activated. The average brace wear time for the study period was 72 +/− 15% (12.6hr/day) of the prescribed time (17.5 +/− 3.8 hours). The curve severity of all subjects on the following clinical visit was the same (within measurement error) as the first visit (32 +/− 5 vs 31 +/− 5 degrees). Compliance was not affected when wearing the monitor.

The smart orthotic was able to improve the efficiency of a conventional brace by maintaining the prescribed interface pressure automatically. This proposed work helps brace candidates wear their braces more effectively and gets the most benefit from the brace treatment. As a result, all participated subjects maintained their Cobb angle within ± two degrees during the study period.

The efficiency of brace treatment for adolescent idiopathic scoliosis is correlated to how the brace has been worn. A smart orthosis was developed to maintain the interface pressure between the brace and the body within the prescribed range during daily activity. Six patients with scoliosis, with Cobb angles of 31 +/− 5 degrees, who were new brace candidates were recruited. They used the system for four weeks: two weeks with monitoring only and two weeks with an automatic feedback activated. The time that the pressure level was in target level range during the study period was increased from 53 +/− 9% to 68 +/− 14% with the feedback activated. This work helps brace candidates wear their braces more effectively and receive the most benefit from the brace treatment. As a result, all subjects who participated in the study maintained their Cobb angles within + two degrees during the study period.

Brace correction based upon mechanical action requires appropriate interface pressure between the body and the brace. A smart orthosis was developed to record how much time (quantity) a brace was worn, how well (quality) it was used and how well the interface pressure was maintained to the prescribed level. Six subjects were recruited and they all were fitted with Boston style braces. Each subject wore the brace for 2 weeks without the force maintenance system activated to serve as the control period, and the remaining 2 weeks with the force maintenance system activated. During the automatic feedback mode, the pressure maintenance system was activated only during the daytime hours (8:00–22:00hrs) to avoid disturbing the patients during sleep. The subject could either return the system to us after 1 month or continue to use the system until the next clinic.

The time that the pressure level was in the target level range during the study period was increased from 53 +/− 9% to 68 +/− 14% with the feedback activated. The average brace wear time for the study period was 72 +/− 15% (12.6hr/day) of the prescribed time (17.5 +/− 3.8 hours). The curve severity of all subjects on the following clinical visit was the same (within measurement error) as the first visit (32 +/− 5 vs 31 +/− 5 degrees). Compliance was not affected when wearing the monitor.

The smart orthosis was able to improve the efficiency of a conventional brace by maintaining the prescribed interface pressure automatically. This project helps brace candidates wear their braces more effectively and gets the most benefit from the brace treatment. As a result, all participating subjects maintained their Cobb angle within +/− 2 degrees during the study period.

To determine the pattern of brace wear compliance over time in both day and night time wear by using objective force measurements within the brace.

Twenty subjects who were diagnosed of AIS, age between nine and fifteen years, and new to brace treatment were recruited in this study. To use the data for analysis, only subjects who used the brace for five hours continuously either in daytime or nighttime were considered. For daytime wear, the selected five hour intervals had to begin with an initial spike in force after a period of non-activity as recorded by the transducer, which would indicate that they had just put on the brace. At night, the measurements began at one am and ended at six am.

Among the twenty subjects, only nine subjects’ data were used for daytime and eleven subjects’ data were used in nighttime. The average wear period was 11.4 ± 4.3 days for the day group, 11.6 ± 3.9 days for the night group. There was a statistically significant decrease in force within the first five hours of consecutive brace wear during daytime hours. The decrease was from 1.4 ± 0.6 (140% of prescribed force) in the first hour to 1.0 ± 0.6 in the fifth hour, a difference of 0.4, which is a 29% drop from the initial force. Most of the drop in force happened between hour one and hour two, as the difference in those two hours is 0.2 ± 0.1 (p = 0.001); between hours two and five the difference did not reach statistical significance. The observed difference between hours one and five for the night group was 0.2 ± 0.2, p = 0.06, which did not reach significance as well. Daytime forces in a Boston Brace tend to decrease over a period of time, but the nighttime forces seem to be maintained at the same level. These results show that daily adjustment of the brace tightness may be required to maintain the tightness level and the efficiency of brace treatment.

Recent studies have shown that scoliotic deformity can be estimated accurately from deformity of the full three hundred and sixty degrees torso shape. However, acquisition of these data requires an expensive multi-scanner system. If it was possible to estimate accurately scoliosis from the back surface shape alone, a single scanner and simplified analysis methods could be used. Here, we estimated the Cobb angle within ten degrees in 84% of forty-six patients from back surface data, compared to 99% within ten degrees for a previous, larger study using the entire torso shape. These results suggested that both back-surface and full-torso models for Cobb angle estimation should be pursued for their potential merits.

The surface deformity of scoliosis, often the primary patient complaint, progresses non-linearly with the underlying spinal deformity. If it was possible to estimate reliably the degree of scoliosis from the surface, adolescent patients with non-progressing scoliosis could be spared harmful X-ray radiation. Some of us have previously estimated the scoliotic Cobb angle from three hundred and sixty degrees torso surface deformity. Here, we tested how accurately the Cobb angle could be estimated from back surface data alone, which are easier and less expensive to obtain than full-torso data.

A genetic algorithm selected the clinical parameters to be used by a neural network to estimate scoliosis deformity from back surface deformity. We had forty-six consecutive patients with right-thoracic curves (Cobb angles eleven to ninety-seven degrees), in whom fifteen indices were available including age, height, bracing status, scoliometer reading, back surface rotation, and cosmetic score of landmark asymmetry. Those data were used by a neural network to estimate the Cobb angle within ten degrees in 84% of patients, a 30% improvement over regression-model accuracy, though less accurate than use of the three hundred and sixty degrees torso shape which estimated up to 99% of curves within ten degrees in a previous study.

Neural network predictive accuracy was better when using the full three hundred and sixty degrees torso shape, but the simpler and more economical acquisition of back surface data alone also gave promising results. This pilot comparison study suggested that both models (using back surface data alone vs. using three hundred and sixty degrees torso data) should continue to be developed in attempts to optimize surface estimation of scoliosis.

We have investigated the contaminating bacteria in primary hip arthroplasty and their sensitivity to the prophylactic antibiotics currently in use. Impressions (627) of the gloved hands of the surgical team in 50 total hip arthroplasties were obtained on blood agar. The gloves were changed after draping, at intervals of 20 minutes thereafter, and before using cement. Changes were also undertaken whenever a visible puncture was detected. The culture plates were incubated at 37°C for 48 hours. Isolates were identified and tested for sensitivity to flucloxacillin, which is a recognised indicator of sensitivity to cefuroxime. They were also tested against other agents depending upon their appearance on Gram staining.

We found contamination in 57 (9%) impressions and 106 bacterial isolates. Coagulase-negative staphylococci were seen most frequently (68.9%), but we also isolated Micrococcus (12.3%), diphtheroids (9.4%), Staphylococcus aureus (6.6%) and Escherichia coli (0.9%). Of the coagulase-negative staphylococci, only 52.1% were sensitive to flucloxacillin and therefore to cefuroxime. We believe that it is now appropriate to review the relevance of prophylaxis with cefuroxime and to consider the use of other agents.

We conducted a randomised, controlled trial to determine whether changing gloves at specified intervals can reduce the incidence of glove perforation and contamination in total hip arthroplasty. A total of 50 patients were included in the study. In the study group (25 patients), gloves were changed at 20-minute intervals or prior to cementation. In the control group (25 patients), gloves were changed prior to cementation. In addition, gloves were changed in both groups whenever there was a visible puncture. Only outer gloves were investigated.

Contamination was tested by impression of gloved fingers on blood agar and culture plates were subsequently incubated at 37°C for 48 hours. The number of colonies and types of organisms were recorded. Glove perforation was assessed using the water test. The incidence of perforation and contamination was significantly lower in the study group compared with the control group. Changing gloves at regular intervals is an effective way to decrease the incidence of glove perforation and bacterial contamination during total hip arthroplasty.

Objectives: To determine the correlation between brace treatment and the brace tightness and treatment compliance

Design: A monitoring device [1] was designed to measure and record the time and temporal profile of the loads on the pressure pad imposed on the trunk during daily activity. The device consists of a programmable digital data acquisition system and a force transducer. Three light emitted diodes (LEDs) were used to indicate the tightness level below 80%, between 80 to 120%, and above 120% of the load level prescribed. Each subject used the indicator on the device to adjust the tightness of the brace so as to achieve the prescribed pad load. The prescribed pad load had been set by his/her physician after the transducer was installed.

Subjects: Eighteen brace candidates, 3 males and 15 females age 13.6 ± 1.8 years, who had worn their braces from 6 months up to 1 year were recruited. All subjects gave their informed consent to participate in this study. The selection criteria were 1) diagnosis of idiopathic scoliosis, 2) ages between 9 – 15 years and 3) prescribed brace treatment. The exclusion criteria were anyone who 1) had other musculoskeletal or neurological disorders, 2) refused to wear the brace, 3) was being weaned from treatment, or 4) was a surgical candidate. Twelve of eighteen subjects have completed their brace treatment. Loads were measured one sample per minute. These twelve subjects used the systems from 3 to 14 days (9.4 ± 4.9 days). All subjects reported that the time they wore their braces was not influenced by wearing the monitor.

Outcome measures: The quality of the brace wear was assessed by how often the brace was worn with zero force (i.e., not worn), below 80%, between 80 to 120%, and above 120% of the load level prescribed in the clinic. The quantity of brace wear was determined by how many hours per day they wore their braces. Three treatment outcomes were defined: improvement, no change, and deterioration. Improvement was defined as a reduction of the Cobb angle, compared to the pre-brace measurement, by more than 5 degrees after weaning; no change was defined as a Cobb angle change of ± 5 degrees after weaning, and deterioration was defined as a Cobb increase greater than 5 degrees after weaning.

Results: One subject had curve improvement, 7 subjects had no change and 4 subjects had curve deterioration. The improvement subject was 84% compliant and wore her brace above or in the target load range 62% of prescribed time. No change subjects were 70 ± 12.5% compliant and wore their braces above or in the target load range 40 ± 24% of prescribed time. Deterioration subjects were 64 ± 10% compliant and wore their braces above or in the target load range only 26 ± 9% of prescribed time.

Conclusions: It appears that tightening the straps to the prescribed level and wearing the brace as much as the prescribed time is important for successful brace treatment. Simply wearing a brace is not enough; it has to be worn tightly and often.

Introduction: Braces are the most generally accepted form of non surgical treatment for adolescent idiopathic scoliosis (AIS). Despite decades of usage controversy still exists regarding the efficacy of this treatment. We believe this controversy continues in part because there are few studies describing the mechanical effect of bracing and linking mechanically effective bracing to changes in the natural history of AIS. If braces are effective, is it because they apply significant mechanical support to a collapsing spine or are they effective for other reasons? A first step towards answering this question is to document the mechanical action of braces during activities of daily living. This would enable researchers to examine the effect of mechanical support on progression of the scoliosis. The objective of this study was to determine the temporal pattern of forces exerted by the pressure pad in Boston braces prescribed for the treatment of AIS.

Methods and results: A force transducer and a programmable data logger were designed to measure loads exerted by the pressure pad over extended periods of time. The loads were recorded at one minute intervals. Braces were adjusted to a prescribed load level and the patients were asked to set the brace tightness to match this target any time the brace was donned. Brace wear data were stratified into: not worn, worn at less than 80% of target, 80–120% of target and greater than 120% of target. Bracing was considered mechanically effective if the load was at least 80% of the prescribed level. Patients were aware of the study and consented to participate.

Thirteen patients were followed from 1 to 16 days, average was 9±5 days. Nine patients were asked to wear their braces 23 hours per day, two for 20 and two for 16 hours per day. Braces were not worn 34±27% of the time logged. When they were worn, patients adjusted the tightness of the brace such that it was < 80% of the target 29±20% of the time, within 20% of target 19±19% and over 120% of target 18±13% of the time. Patients wore their braces at or above the target levels 33% of the time logged or 8 hours in a typical day. Subjects had no difficulties using the data logger and none complained that it interfered with brace wear. Reviewing individual histories suggested that subjects did not alter their brace wear pattern because of the data logger.

Conclusion: The mechanical effectiveness of the brace varies considerably over the normal course of wear but seldom does it provide the support intended. While patients wear their braces for about 16 hours per day, it is mechanically effective for 8 hours only.