Indications and results for the Exogen™ ultrasound system in the management of non-union: A 59-case pilot study.

INTRODUCTION:
This pilot series sought to assess the use of external ultrasound stimulation (Exogen™) in the treatment of femoral or tibial non-union.
MATERIALS AND METHODS:
A continuous retrospective study was conducted from 2004 to 2009. It included patients with a non-united fracture or osteotomy at 6 months or more post-surgery, with less than 10mm inter-fragment gap. Daily 20-min ultrasound sessions were continued until bone healing was achieved or for a maximum 6-month duration. Radio-clinical control was performed at months 3 and 6; treatment compliance and transmitter positioning were checked at each follow-up visit.
RESULTS:
Sixty non-unions were included in the series. One patient was excluded for early material breakage. Mean fracture-to-surgery interval was 271 days. The 6-month consolidation rate was 88%. There was no loss to follow-up. Mean ultrasound treatment duration was 151 days (range, 90-240 days). Bone healing correlated significantly with stability of the internal fixation assembly (P=0.01). The seven cases of failure included four fixations,considered unstable at inclusion, one femoral non-union associated with BMI 45 and one inadequate subchondral roughening (at the time of arthrodesis). There was a significant difference in delay to non-union treatment start between the groups with (251 days) and without (420 days) bone healing.
DISCUSSION:
The present results are in line with the literature. The main prognostic factors were fracture fixation stability, short time to treatment, and inter-fragment gap less than 10mm. Bone healing rates in the literature are around 80% for non-union treated at around 6 months, versus 60% for more than 12 months' delay. Factors such as gender, bone site, smoking, numbers of previous operations or type of osteosynthesis do not impact consolidation. External treatment offers an alternative to traditional surgery (graft, or bone-marrow concentrate or bone morphogenetic protein injection), provided that the fracture fixation is stable. Bone healing rates are better, and the procedure is non-invasive. External treatment results using ultrasound are similar to those using electromagnetic fields; the main difference lies in treatment session duration, which is 20min for ultrasound, versus 3hours for electromagnetic fields. Active patient commitment is vital, as the treatment is delivered at home, although the machine is equipped with a monitor to count treatment cycles.
CONCLUSION:
The 88% bone healing rate supports advocating first-line implementation in non-union of less than 10mm with stable osteosynthesis. This rate is higher than in traditional surgery, with a unit cost at least 60% lower: €1772 for external therapy, versus €4480 for decortication with or without fracture fixation exchange (itemized 08c50 under the French healthcare treatment coding system).
LEVEL OF EVIDENCE:
Level IV. Retrospective therapeutic study.
Copyright © 2012. Published by Elsevier Masson SAS.
PMID: 22424956