Each year more than 70 billion standard units of antibiotic are prescribed to treat bacterial infections worldwide. In addition, at least 63,000 tons of antibiotics are consumed by livestock for growth promotion and disease prevention. The result of this overuse of antibiotics is a spiraling increase in resistance. In the United States and Europe, antibiotic resistant bacteria are responsible for more than 4 million infections and approximately 50,000 deaths annually. In addition, bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) have increased in prevalence in hospitals over the last three decades. Such bacteria are particularly problematic in postoperative infections, exacerbating treatment through the development of biofilms, especially on medical implants which are virtually impossible to treat without removal and replacement of the device.

This presentation will show how non-invasive preclinical imaging (optical, PET and CT) is being used to better understand the establishment and development of bacterial infections in vivo, and how best to treat them. In particular, data will be shown as to how preclinical imaging can be used to monitor bacterial infections on orthopaedic implants, and how this technology might be translated into the clinic.

The natural history of gait pattern change in children with spastic diplegia is a transition from toe walking to progressive hip and knee flexion with eventual crouch gait. This has been attributed to the adolescent growth spurt, progressive lever arm dysfunction, and iatrogenic weakening of the soleus with isolated tendo achilles lengthening (TAL). The relative contribution of TAL to the development of crouch gait is uncertain. The purpose of this study was to identify the frequency of crouch gait in spastic diplegic patients with and without history of prior TAL.

Patients with spastic diplegia greater than 10 years of age with instrumented gait analysis were reviewed. Exclusion criteria included diagnosis other than cerebral palsy, prior dorsal root rhizotomy, or incomplete past surgical history. Patients were divided into three groups: Group 1, no prior orthopaedic surgical intervention; Group 2, prior orthopaedic surgery without TAL; Group 3, prior orthopaedic surgery with TAL. Instrumented gait analysis data was analysed. Gait data were analysed using a single randomised limb from each patient.

One hundred and seventy-eight patients were identified: 39 in Group 1, 49 in Group 2, and 90 in Group 3. Mean time from TAL to gait analysis was 7.5 years (range 1.0–14.6 years). Mean age at TAL was 6.3 years (range 1.2–17.5 years). There was no significant difference in age, BMI, walking speed, or cadence between groups. Kinematic analysis showed no significant difference in mean stance phase maximum knee or ankle flexion between groups. There was no significant difference in frequency of increased mid stance knee flexion between groups (Group 1, 53.8%; Group 2 46.9%; Group 3, 43.3%, p=0.546). There was a trend towards increased frequency in excessive stance phase ankle dorsiflexion in Group 3 (60% Group 3 vs 46.2% Group 1, and 40% Group 2, p=0.071). Crouch gait (stance minimum hip flexion > 30, mid stance minimum knee flexion > 200, and stance maximum ankle dorsiflexion > 150) was seen with similar frequency in all groups (Group 1, 23.1%; Group 2, 18.4%; Group 3, 26.7%; p=0.544).

There is a trend towards increased frequency of excessive stance phase ankle dorsiflexion in spastic diplegic patients with prior TAL. However, no significant difference in frequency of crouch gait between patients with and without history of TAL was identified. Crouch gait is part of the natural history of gait pattern change in spastic diplegic patients independent of prior surgical intervention.