Clinical feasibility of fracture healing assessment through continuous monitoring of implant load.

Current fracture fixation follow-up is based on subjective radiological and clinical examination. Efforts to objectify the procedure have been undertaken since decades. Assessment of implant load as an indirect predictor of callus maturity has so far failed to enter clinical routine due to limited practicability, technical obstacles and its snap-shot nature. We recently introduced the concept of continuous implant load monitoring to aid in diagnosing fracture healing progression. This study aimed at investigating the feasibility of the system in a clinical context. Ten patients treated with Taylor-Spatial-Frame external fixators following pathological tibia fractures were equipped with a Fracture Monitor device attached to a fixator-strut and were monitored until hardware removal. Two patients were excluded due to technical issues. Implant load and fracture activity was continuously and autonomously measured for 139 ± 89 days (mean ± SD). Data was wirelessly collected with consumer smartphones. Relative implant load initially rose for 34.1 ± 22.2 days and finally declined to a level of 45.0 ± 33.8% of the maximum implant load. In five patients the load dropped below 50% of the maximum load. These patients underwent hardware removal according to the clinical assessment. In three patients, whose external fixators were exchanged to internal fixation at the end of the study, implant load did not drop below the 50% margin. The continuous measurement principle allows resolving implant load progression and appears indicative for the bone healing status. Data can be acquired in a homecare setting and is believed to provide valuable information to support timely healing assessment and enable patient specific after-care.