Dynamic ultrasound assessment of the effects of knee and ankle position on Achilles tendon apposition following acute rupture.

BACKGROUND: Previous reports have suggested that knee flexion improves tendon edge apposition following acute rupture of the Achilles tendon. The aim of the present study was to determine, with use of ultrasonography, the effects of knee and ankle position on the Achilles tendon gap distance in patients with an acute rupture. METHODS: Twenty-six patients with a unilateral acute complete Achilles tendon rupture that had been confirmed with ultrasonography were recruited within a week after the injury. The mean age at the time of presentation was forty-one years. Ultrasound measurements included the location of the rupture and the gap distance between the superficial tendon edges with the ankle in neutral and the knee extended. The gap distance was sequentially measured with the foot in maximum equinus at the ankle and with 0°, 30°, 60°, and 90° of knee flexion. RESULTS: The mean distance of the rupture from the calcaneal enthesis was 52 mm (range, 40 to 76 mm). The mean gap distance with the ankle in neutral and the knee extended was 12 mm (95% confidence interval, 10 to 13 mm). This distance decreased to 5 mm (95% confidence interval, 4 to 7 mm) when the foot was placed in maximum ankle equinus with 0° of knee flexion and to 4 mm (95% confidence interval, 3 to 5 mm) with 30° of knee flexion, 3 mm (95% confidence interval, 2 to 4 mm) with 60° of knee flexion, and 2 mm (95% confidence interval, 1 to 2 mm) with 90° of knee flexion. Expressing the reduction in gap distance with each successive position as a percentage of the gap distance with the knee extended and the ankle in neutral revealed a mean reduction of 55.7%, 64.4%, 75.4%, and 84.8% with maximum ankle equinus and 0°, 30°, 60°, and 90° of knee flexion, respectively. The difference in gap distance between each of these positions was significant (p < 0.05). CONCLUSIONS: Maximum ankle equinus alone significantly reduces the gap distance after acute Achilles tendon rupture. Increasing knee flexion further reduces the gap distance by small increments that, although significant, may not be clinically important.

Magnetic resonance imaging assessment of spinal inflammation in ankylosing spondylitis: standard clinical protocols may omit inflammatory lesions in thoracic vertebrae.

OBJECTIVE: Radiologic assessment of spinal inflammation in patients with ankylosing spondylitis (AS) relies primarily on magnetic resonance imaging (MRI), although little is known about the distribution of inflammatory lesions within the structures of the spine. Our objective was to compare the distribution of inflammatory lesions centrally and laterally within the thoracic and lumbar spine vertebral bodies. METHODS: We studied 49 patients with AS who were scanned with STIR and T1-weighted spin-echo MRI of the whole spine. Scans were read by 2 musculoskeletal radiologists, with a third reader as the arbitrator. Controls included 6 age-matched individuals. We recorded bone marrow edema on STIR images from each vertebral body, separately identifying central and lateral slices. The latter were defined as images that included or were lateral to the pedicle. Interreader reproducibility was assessed by kappa statistics. RESULTS: Inflammation was present in 263 (45%) of 588 thoracic and 86 (35%) of 245 lumbar vertebrae; the mean number of affected thoracic and lumbar vertebrae per patient were 5.4 and 1.8, respectively. Inflammation was present in the lateral aspect of 219 (37%) of 588 thoracic vertebrae and 45 (18%) of 245 lumbar vertebrae (P < 0.001). Lesions were more common laterally than centrally for all thoracic vertebrae except for T7. Involvement of only the lateral slices was observed in as many as 19.6% of thoracic vertebrae. CONCLUSION: Evaluation of spinal inflammation by MRI may omit lesions in up to 20% of inflamed thoracic vertebrae if both scanning and image assessment do not include sagittal slices that extend to the lateral edges of all vertebrae.