Purpose:

To develop a method for depth-wise analysis of subchondral bone that considers the gradient of bone volume, density and organization between the articular surface and the marrow cavity.

Method: Since 30% of patients fail microfracture for contained chondral lesions, our hypothesis was that early subchondral sclerosis increases compaction of bone around microfracture holes, leading to failed cartilage repair. Human osteochondral segments from the knee joint were characterized macroscopically using the Outerbridge score, then imaged at 45 micron resolution using microCT. Regions of interest (ROI) were chosen under normal cartilage and abnormal cartilage (Outerbridge Score=1). Routine Bone mineral density (BMD) analysis was performed on each ROI using GE MicroView™ analysis software. Additional depth-wise analysis of BMD was done by exporting each ROI was a density map, and calculating the mean, standard deviation and rate of change of BMD by slice in the vertical (coronal) plane. Plots of normal and early OA data by depth were compared. Microfracture holes were made in normal and sclerotic subchondral bone, and depth-wise measurements of subchondral compaction around the holes were made were made.

Results: Bone under normal versus OA cartilage was very subtly different in microCT images, but ROI microCT analysis showed that the OA samples were more mineralized and contained more bone. Using the depth-wise analysis algorithm, automated detection and measurement of the subchondral bone plate and other discrete structures was possible. The depth-wise analysis confirmed that the osteoarthritic subchondral bone plate had a higher BMD and bone volume fraction, but also showed that the rate of change (gradient) in BMD was greater. Horizontally orientated trabeculae and other anomalies were found in OA bone that contributed a more variable BMD in trabecular bone at up to 5 mm from the articular surface. Bone with early sclerotic changes had significantly (p< .01) more bone volume fraction and BMD (p< .05) around microfracture holes in this ex vivo experiment.

Conclusion: An enhanced picture of subchondral bone plate and trabecular bone anomalies can be appreciated using a depth-wise approach to image analysis. Both sclerosis and osteopenia have been reported in OA and models of OA, but this analysis shows that variability and gradient of BMD change adjacent to the articular cartilage is a significant feature of OA. This is consistent with some theories of OA progression that implicate stress concentration between the cartilage and subchondral bone plate leading to cartilage degeneration. More importantly, bone sclerosis has a direct effect on the amount of compaction around microfracture holes, so improvements in microfracture technique are needed to avoid this.

There has been concern over the safety of the upright position for shoulder surgery from anaesthetists uncomfortable with the risk of reduced cerebral blood flow (CBF). Because there are no studies documenting what happens to CBF during upright surgery we aimed to measure CBF through an indirect and non-invasive method using recently available Ultrasound monitoring equipment.

This study randomised patients into awake (interscalene block alone) and GA with block, and indirectly measured the CBF by using a validated Doppler technique on carotid flow both before and during the shoulder procedure. Non-invasive and invasive measurements of mean arterial pressure were made throughout the procedure, together with doppler measurement of carotid flow following preoperative measurement of carotid contribution to cerebral flow in the radiology department by an experienced sonographer. All measurements recorded in real time and charted independently.

This study has shown that CBF in both groups were consistent with the expected values, and CBF remained proportionate in supine to upright. CBF values in the block alone group were generally lower than the GA group. In the GA group the MAP dropped lower, requiring use of adrenergic drugs to bring the pressure up. Despite the significant drop in MAP, the CBF was still high. This could signify cerebral autoregulation is a significant factor in the upright position.

We have shown the feasibility of use of DOppler to indirectly measure CBF during upright surgery. Despite the predicted drop in MAP in this position with GA, we could NOT show a concurrent drop in CBF, demonstrating that much more complex factors regulate the CBF in these patients. Clearly, monitoring is the key to safe administration of anaesthetic in the upright position.

A generic measure of health related quality of life was used to evaluate outcome following ACL reconstruction. This study quantifies the domains of poorer health-related quality of life and provides pre- and postoperative SF-36 scores for patients with ACL deficient knees. Pre-operative Sf-36 scores in ACL deficient knees were significantly lower than age matched normals in the physical domains of physical functioning, role-physical and bodily pain (p< 0.001). Post-operatively, SF-36 scores were significantly improved (p< 0.001) in all domains except general health and social functioning.

Evaluation of the ACL injured knee and the success of reconstructive surgery has traditionally focused on an assessment of knee function. These have proven to be poor indicators of general functional outcome and health related quality of life. The purpose of this study was to use the SF-36 survey to determine whether health related quality of life in patients with ACL deficient knees differed from that of healthy individuals and whether SF-36 scores improved after undergoing ACL reconstruction.

Sixty patients with ACL deficient knees underwent ACL reconstruction using arthroscopically assisted patellar tendon insertion. Prior to surgery and a minimum of two- years post-operatively, patients completed the SF-36 general Health Survey questionnaire. Pre- and post-operative SF-36 scores were compared to each other and to standard scores obtained from a healthy population of a similar age.

Pre-operative Sf-36 scores in ACL deficient knees were significantly lower than age matched normals in the physical domains of physical functioning, role-physical and bodily pain (p< 0.001). Post-operatively, SF-36 scores were significantly improved (p< 0.001) in all domains except general health and social functioning. Comparison between age matched normals were significantly higher in the domains of role-emotional, vitality, mental health and general health

A generic measure of health related quality of life was used to evaluate outcome following ACL reconstruction. This study quantifies the domains of poorer health-related quality of life and provides pre- and post-operative SF-36 scores for patients with ACL deficient knees.

Our finding indicates that ACL reconstruction using patellar tendon autograft with arthroscopically assisted technique improved ling term health related quality of life.

Metallic implants are used frequently in the operative repair of joints and fractures in orthopaedic surgery. Orthopaedic implant infection is chronic and biofilm based. Present treatment focuses on removing the infective substratum and implant surgically as well as prolonged anti-microbial therapy. Biofilms are up to 500 times more resistant than planktonic strains of bacterial flora to antibiotics. Silver coatings on polymers and nylon (catheters, heart valve cuffs, burn dressings) have shown inhibition of this biofilm formation in its adhesion stage. Our aim was to deposit effective, minute, antibacterial layers of silver on orthopaedic stainless steel and titanium K-wires and to investigate the effect of these coatings when exposed to Staphylococcus Aureus biofilms in an in vitro and in vivo environment.

Combining magnetron sputtering with a neutral atom beam (Saddle Field) plasma source at 10⁻⁴ mbar in argon gas at temperatures of 60°C, a silver coating of 99.9% purity was deposited onto stainless steel and titanium orthopaedic K-wires. Coating thickness measurements were obtained using glancing angle x-ray diffraction of glass slides coated adjacent to wires. Magnetron parameters were modified to produce varying thickness of silver. Adhesiveness was examined using Rockwell punch tests. Silver leaching experiments were carried out in phosphate buffered saline at 37°C for 48 hours and using inductive coupled plasma spectrometry to assess leached silver ions. Surface microscopy visualised physical changes in the coatings.

Biofilm adhesion was determined by exposing wires to Staphylococcus Aureus ATCC 29213 – NCTC 12973 for 15 minutes to allow biofilm initiation and adhesion. Wires were then culturing for 24 hours at 37°C in RPMI. Subsequently, wires were sonicated at 50Hz in ringer’s solution and gently vortexed to dislodge biofilm. Sonicate was plated out by log dilution method on Columbia blood agar plates. Bacterial colonies were then counted and changes expressed in log factors.

K-wires were coated with 1 to 50 nm of silver by running the magnetron sputtering at low currents. These coatings showed excellent adhesive properties within the 48 hours exposed with only 3.7% of silver leaching in buffered saline. The silver coated stainless steel wires showed a log 2.31 fold reduction in biofilm formation as compared to control wires (p< .001), Student t-test), the silver coated titanium wires showed a log reduction of 2.06, (p< .001, Student t-test). Animal studies demonstrated enormous difficulty in reproducing biofilm formation and showed a 0.49 log fold reduction in the titanium group when exposed to Staph Aureus (p< .01, Student t-test), the other groups showed no statistically significant reduction.

We have perfected a method of depositing tiny layers of anti-bacterial silver onto stainless steel and titanium, which is anti-infective in vitro but not in vivo. Further studies involving other metal coatings such as platinum and copper are warranted.