Post-operative longitudinal monitoring of osteochondral defects of the talus with ultrasound after bone marrow stimulation.

The separation of a fragment of cartilage and its subchondral bone in a joint
is named an osteochondral defect (OCD). OCDs are mostly caused by a traumatic
event and can involve all joints, but in practice the knee, the ankle and the
elbow are most frequently damaged1-3. These OCDs cause impairment because of
deep joint pain and may contribute to premature development of
osteoarthritis3-5. The latter is a major cause of disability and represents a
high socioeconomic burden to society.

Diagnosis takes place with MRI- or CT-scan. Bone marrow stimulation is the
first-line treatment option where loose cartilage pieces are removed and holes
are drilled in the underlying bone to stimulate an intrinsic healing process.
Although the treatment is quite successful, the results are fair to poor for
about 10% of the patients. This can only be partially explained by factors such
as defect size. Additionally, little is known about the true nature of the
healing process in vivo in patients. So, there is a need for in vivo monitoring
of the regeneration to optimize treatment of osteochondral defects. A previous
pilot patient study showed that ultrasound can visualize OCDs in the anterior
part of the talar dome. Ultrasound is desired as monitoring tool because it is
truly noninvasive and relatively cheap, which allows an increased sample
frequency to monitor in vivo cartilage regeneration.

The aim of this study is to visualize and to quantitatively document the
regeneration process of osteochondral defects in the human ankle following bone
marrow stimulation by longitudinal monitoring at short intervals in time with
ultrasound.

In total, 5 patients with a CT confirmed anterior OCD of the talus
(Berndt-Hardy-Loomer grade II-V) are recruited. Patients should be older than
18 years, competent and scheduled for a BMS treatment of the OCD.
Preoperatively, a 3D ultrasound sweep will be acquired to collect a 3D volume
of the entire visible talar surface including the OCD. Postoperatively the
patients are imaged with the 3D ultrasound sweep executed at 2, 3, 4, 5 and 6
weeks. After that there will be an ultrasound at 8, 10 and 12 weeks.
Furthermore, 2 more echo sweeps will take place at 6 months and one year at
regular follow up appointments. These 3D ultrasound volumes will all be
registered to MRI- or CT-data as part of the routine diagnostic protocol,
which serve as reference. A routine control CT scan will also be performed at
one year.

Patients that participate in the study could benefit from the additional
imaging with ultrasound as it might assist in achieving adequate diagnosis. As
ultrasound is a truly noninvasive imaging modality, no additional risks or
complications are expected. The disadvantage for patients is that they have to
be present longer than the time scheduled for a follow up appointment to
execute the ultrasound. This will take approximately 30 minutes per ultrasound
sweep. Next to the standard care appointments there will also be 6 additional
appointments for an ultrasound sweep. In total, patients will undergo 11
ultrasound sweeps. This correlates with 5 * hours of additional time needed
divided over a period of 12 months.