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20 patients having received an AO large external fixator at the tibia will be equipped with a data logger device (AO Fracture Monitor) attached post-operation to a connection rod of the external fixator. The device continuously measures deformation of the fixator frame due to weight bearing for up to 6 months by means of a strain gauge. Several parameters are calculated from the recorded change in the strain signal and are stored at a regular interval.
Maturation of fracture callus leads to unloading of the fracture fixation hardware due to an increased load-share of the repair tissue. A novel data logger device (AO Fracture Monitor) continuously measures the decline in fixation hardware deflection under physiological loading as indirect indicator for the healing progress. Parameters obtained from the data logger device carry potential to significantly improve the assessment of fracture healing in the future. Meaningful interpretation of measurements requires a set of clinical reference data.
20 patients having received an AO large external fixator at the tibia will be equipped with a data logger device (AO Fracture Monitor) attached post-operation to a connection rod of the external fixator. The device continuously measures deformation of the fixator frame due to weight bearing for up to 4 months by means of a strain gauge. Several parameters are calculated from the recorded change in the strain signal and are stored at a regular interval. Data is collected from the AO Fracture Monitor at follow-up visits of the patient by wireless data transfer. Together with additional variables such as treatment details, fracture healing and pain reported by the patient, the collected data is used to build up a database. Data from the AO Fracture Monitor will be correlated with patient data to investigate the relevance and reliability of the data derived from the AO Fracture Monitor.
In this phase, the study does not imply changes on the operational treatment, nor does it allow for therapeutic consequences based on the derived data.
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| SmartFix | Device | AO Fracture Monitor attached postoperatively to a connection rod of the external fixator. The device continuously measures deformation of the fixator frame due to weight bearing for up to 4 months by means of a strain gauge. |
| Measure | Description | Time Frame |
|---|---|---|
| Changes in Parameters derived from the AO Fracture Monitor during bone healing | AO Fracture Monitor:
| Discharge, 1 month, 2 months, 3 months, 4 months, 5 months, 6 months |
| Measure | Description | Time Frame |
|---|---|---|
| Change in Pain during bone healing | Pain measured with visual analog scale (VAS) | Preoperative, Discharge, 1 month, 2 months, 3 months, 4 months, 5 months, 6 months (after surgery) |
| Change in weight-bearing during bone healing |
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Inclusion Criteria:
Age 18 years and older
Diagnosis of Femoral or tibial fracture (AO 41-43)
External fracture fixation with AO large external fixator
Capable of at least partial weight-bearing
Informed consent obtained, i.e.:
Exclusion Criteria:
Preoperative exclusion criteria:
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Patients with Tibia shaft fracture and external fracture fixation (AO large external fixator).
Patients capable of at least partial weight-bearing (or expected to do so in the course of healing).
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| Name | Affiliation | Role |
|---|---|---|
| Dankward Höntzsch, Professor | Berufsgenossenschaftliche Unfallklinik Tübingen | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Berufsgenossenschaftliche Unfallklinik | Tübingen | Baden-Wurttemberg | 72076 | Germany |
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| ID | Term |
|---|---|
| D013978 | Tibial Fractures |
| ID | Term |
|---|---|
| D050723 | Fractures, Bone |
| D014947 | Wounds and Injuries |
| D007869 | Leg Injuries |
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Documentation of allowed weight-bearing
| Discharge, 1 month, 2 months, 3 months, 4 months, 5 months, 6 months (after surgery) |
| Repeated reference deformation at a load of 20 / 30 kg | Two reference deformation values are measured under a load 20 kg and 30 kg respectively. The patient steps with his injured leg on a bathroom scale and loads it first with the reference load of 20 kg. The investigator then starts the measurement of the corresponding deformation value. After an acoustic signal indicates the end of the measurement, the procedure is repeated with a reference load of 30 kg. If the patient is not able to put the required load on his leg (e.g. due to pain), the reference value should be measured at a lower load with a note of the actually applied load in the patient record. | Discharge, 1 month, 2 months, 3 months, 4 months, 5 months, 6 months (after surgery) |
| Patient information |
| Up to 4 weeks before surgery |
| Treatment information |
| Discharge |
| Development of the radiological healing assessment: RUST system | The Radiographic Union Score for Tibial fractures (RUST score) is a reliable score to assess the healing of tibial fractures. Each of the four cortices (anterior, posterior, medial and lateral) is given a value from 1 to 3, depending on the presence of a callus and the visibility of the fracture line. The sum of the individual cortical scores results in a RUST value between 4 (definitely not healed) to 12 (definitely healed). To investigate, whether patient activity as measured by the AO Fracture Monitor correlate with the radiological assessed course of healing. | Discharge, 1 month, 2 months, 3 months, 4 months, 5 months, 6 months (after surgery) |