Automated surgical screwdriver: automated screw placement.

The use of power screwdrivers and drills for tapping and screw insertion in surgery is becoming more common. It has been established from clinical observations that the use of a small air drill for inserting self-tapping screws provides improved coaxial alignment and precision, and that the drill should be stopped before the screw head is completely seated on the plate, presumably to reduce the risk of over-tightening. The risk of overrun and over-tightening during tapping and screw insertion is increased with the use of power tools. Prevention of over-tightening is dependent upon when the surgeon detects the onset of tightening, both visually and from the feel of the rapid increase in torque. If detection is too late, then over-tightening or stripping can occur. This study is concerned with using a mechatronic screwdriver to control the tapping depth and to prevent the over-tightening of screws. The effects of various parameters upon the torque profile during tapping and screw insertion have been investigated in synthetic bone and sheep tibia. An automated system is proposed for preventing over-tightening of pre-tapped and self-tapping screws when attaching a surgical plate to a sheep tibia in vitro. The system was used to attach a plate to a sheep tibia using self-tapping screws. The mean torque of the screws inserted using the automated system was 35 per cent of the stripping torque.

Brief exposure of 0.05% chlorhexidine does not impair non-osteoarthritic human cartilage metabolism.

Jet lavage with chlorhexidine 0.05% is an effective means of wound decontamination with 99% of bacteria removed or killed after 1min. Reports of chondrolysis following exposure to concentrations of >0.05% or prolonged exposure to chlorhexidine have curtailed its use in orthopaedic practice. Using radiolabelled sulphur uptake to measure cartilage metabolism, we quantitatively assessed the in-vitro effect of osteoarthritic and non-osteoarthritic human cartilage exposure to chlorhexidine 0.05% for 1min and 1h. The metabolism of non-osteoarthritic cartilage was not significantly affected by a 1min exposure to chlorhexidine 0.05% whereas that of osteoarthritic cartilage was markedly impaired. Prolonged exposure for 1h markedly affected both types of cartilage. These results are encouraging in that 0.05% chlorhexidine may have a role in the decontamination of contaminated open joint injuries in patients with no signs of osteoarthritis. Until there is further understanding of the mechanism underlying reported incidents of chondrolysis following its use, however, it cannot be recommended for the irrigation of 'clean' articular cartilage.

X-ray-based machine vision system for distal locking of intramedullary nails.

In surgical procedures for femoral shaft fracture treatment, current techniques for locking the distal end of intramedullary nails, using two screws, rely heavily on the use of two-dimensional X-ray images to guide three-dimensional bone drilling processes. Therefore, a large number of X-ray images are required, as the surgeon uses his/her skills and experience to locate the distal hole axes on the intramedullary nail. The long-term effects of X-ray radiation and their relation to different types of cancer still remain uncertain. Therefore, there is a need to develop a surgical technique that can limit the use of X-rays during the distal locking procedure. A robotic-assisted orthopaedic surgery system has been developed at Loughborough University to assist orthopaedic surgeons by reducing the irradiation involved in such operations. The system simplifies the current approach as it uses only two near-orthogonal X-ray images to determine the drilling trajectory of the distal locking holes, thereby considerably reducing irradiation to both the surgeon and patient. Furthermore, the system uses robust machine vision features to reduce the surgeon's interaction with the system, thus reducing the overall operating time. Laboratory test results have shown that the proposed system is very robust in the presence of variable noise and contrast in the X-ray images.

Doxycycline inhibits bone resorption by human interface membrane cells from aseptically loose hip replacements.

Matrix metalloproteinases (MMPs) may have a role in the process of aseptic loosening. Doxycycline has been shown to inhibit MMPs. Our aim was to investigate the potential pharmacological effect of doxycycline on aseptic loosening. We used radiolabelled mouse calvariae cultured with human interface membrane cells from aseptically loosened hips. Bone resorption was confirmed in this model. The effect of doxycycline was assessed by culturing dead radiolabelled bone discs with cells from the interface membrane with doxycycline. The control group consisted of the same culture system without doxycycline. Supernatant 45calcium and the total 45calcium remaining in the bone discs at the completion of the culture were used to measure osteolysis. We found that doxycycline can inhibit osteolysis at the interface membrane of aseptically loosened hips. This may have therapeutic implications for the treatment of patients with aseptic loosening of total joint replacements.

Body-exhaust suit versus occlusive clothing. A randomised, prospective trial using air and wound bacterial counts.

We randomly allocated 50 total knee replacements to scrub teams wearing body-exhaust suits (BES) or Rotecno occlusive clothing. The effectiveness of the clothing was assessed using air andwound bacterial counts. Bacteria were recovered from 62% of wounds (64% BES, 60% Rotecno). The mean air count was 0.5 CFU/ m3 with BES and 1.0 CFU/m3 with Rotecno (p = 0.014). The mean wound counts were 14 bacteria/wound with BES and eight bacteria/wound with Rotecno (p = 0.171). There was no correlation between the air and wound counts (r = -0.011, Spearman's). The higher air counts suggest that Rotecno occlusive clothing is less effective than BES, but wounds were equally contaminated with both types of clothing suggesting that at very low levels of air contamination the contribution of bacteria to the wound from the air is irrelevant. Even doubling the air counts from 0.5 to 1.0 CFU/m3 had no detectable effect on the wound. This allows a reassessment to be made of other sources of contamination the effect of which would previously have been overwhelmed by contamination from air.

A randomised prospective comparison of Rotecno versus new Gore occlusive surgical gowns using bacterial air counts in ultraclean air.

Ultraclean air (UCA) in operating theatres is defined as <10 colony-forming units (cfu)/m(3). The current European standards for surgical gowns are contained in EN13795 but these do not include containment of bacterial dispersal as a standard test. A trial in 2003 found that there were bacterial air counts of 1 cfu/m(3) with Rotecno gowns and 0.5 cfu/m(3) with body exhaust suits in total knee arthroplasty (TKA). This study compared bacterial air counts using Rotecno gowns with a new type of occlusive gown made from Gore liquid-proof fabric, which were superior to the Rotecno gowns on standard EN13795 laboratory testing. Fifty-six joint replacements were allocated randomly either to Rotecno or to Gore gowns with stratification into TKA, total hip arthroplasty (THA) or revision THA. Airborne bacteria were collected from within 30 cm of the wound for the first 10 min of surgery using a Casella slit sampler. The new gowns were associated with higher air counts (3.7 cfu/m(3)) than the Rotecno gowns (1.2 cfu/m(3)) (P<0.001). Three of the Gore samples exceeded the clean air standard of 10 cfu/m(3). In TKA patients, the existing Rotecno gowns, now many years old, had higher air counts (2.0 cfu/m(3)) than in the 2003 trial (0.8 cfu/m(3)) (P<0.001). The new gowns were superior in standard laboratory tests but not superior at preventing airborne bacterial dispersal. Rotecno gowns, although many years old, were still effective. This study highlights the importance of testing new materials in a clinical environment with UCA; in-vitro testing alone is probably not an adequate assessment.

Displaced intra-articular calcaneal fractures: 15-year follow-up of a randomised controlled trial of conservative versus operative treatment.

AIM: To report the 15-year follow-up of displaced intra-articular calcaneal fractures from a randomised controlled trial of conservative versus operative treatment published in 1993. PATIENTS AND METHODS: Of the initial study, 46 patients (82%) were still alive at a mean of 15 years post injury and 26 patients (57%) agreed to review. The patients had been randomly allocated to either conservative or operative treatment in the original study. Clinical [American orthopaedic foot and ankle society hindfoot scale (AOFAS), foot function index (FFI) and calcaneal fracture score] and radiological (Böhler's angle and calcaneum height) outcome measures were used. The grade of osteoarthritis was also assessed at long-term follow-up. RESULTS: At long-term follow-up, the clinical outcomes were not different between conservative versus operative treatment. AOFAS hindfoot scale: conservative=78.5 and operative=70, p=0.11; FFI: conservative=24.4 and operative=26.9, p=0.66; calcaneal fracture score: conservative=70.1 and operative=63.5, p=0.41. The radiological outcomes were also not different between both groups. Böhler's angle: conservative=10.4 degrees and operative 16.9 degrees , p=0.07; height of calcaneum: conservative=37.2mm and operative=38.2mm, p=0.57; grade of osteoarthritis of the sub-talar joint: p=0.54. There was no correlation between Böhler's angle and the outcome measures in either group. CONCLUSION: The results of this 15-year follow-up of displaced intra-articular calcaneal fracture randomised controlled trial were equivalent between conservative and operative treatment and demonstrate similar findings to those at one year follow-up.

Trauma rapid review process: efficient out-patient fracture management.

INTRODUCTION: Our hospital operates a consultant-led, rapid review process of X-rays and case notes of all musculoskeletal injury patients on a daily basis. This compares with other centres where patients are reviewed in out-patient fracture clinics soon after injury. The aim of this study was to evaluate the effectiveness of this consultant-led, rapid review process compared to standard consultant fracture clinics. PATIENTS AND METHODS: A prospective study of the rapid review process over 4 weeks of all musculoskeletal injury patients was conducted. The total number of patients referred per day, time taken to review these patients X-rays and case notes, number of recalls and reason for recall were documented. This was compared to consultant-led fracture clinics, which included time taken to review patients. RESULTS: A total of 797 patients were processed through the rapid review over 4 weeks: 53 (6%) patients were recalled, 32 (4%) for a change of management and 21 (2.6%) because of lack of information. The mean number of patients referred per day was 28 taking a mean of 28 min; thus the mean time to review one patient was 1.0 min. The mean number of patients recalled per day was two. The mean time taken to review a patient in a standard fracture clinic was 11 min. Therefore, the total time that would have taken to review 28 patients in a standard fracture clinic would be 308 min. CONCLUSIONS: A consultant-led, rapid review process of all patients with musculoskeletal injury is a very efficient process. The rapid review process saves clinic time and resources, minimises delays in clinical decision-making and saves the patient an unnecessary visit to the outpatient department.

Adhesive capsulitis of the shoulder: the rate of manipulation following distension arthrogram.

To determine the rate of manipulation under anaesthesia (MUA) following distension arthrogram for adhesive capsulitis of the shoulder. Thirty-nine patients (42 shoulders) between 1998 and 2004 were treated with distension arthrogram for adhesive capsulitis diagnosed by the clinical picture of progressive pain and stiffness. Capsular disruption into the subscapular bursa was demonstrated in 40 of the 42 shoulders (95%). Thirty-seven of 42 (88%) shoulders were painfree following distension arthrogram. 15 of 42 (36%) shoulders underwent MUA following distension arthrogram for stiffness although 10 of these (67%) were painfree. Prior to distension arthrogram, the range of external rotation (ER) was no different between those that had MUA and those that did not (P = 0.36). The improvement in ER was 33% (P = 0.28) in those that had MUA and 50% (P = 0.001) in those that did not. The only complication was a vasovagal episode during the procedure. Distension arthrogram can be used as a therapeutic procedure for achieving symptomatic pain relief in the majority of adhesive capsulitis and decrease the rate of MUA of the shoulder.