Session IX - Tibia

Low-Intensity Ultrasound and Healing of Intramedullary Fixed Tibial Fractures

Sune Larsson, MD, PhD; Abbas Emami, MD, PhD; Marianne Petrén-Mallmin, MD, PhD; Anders Larsson, MD, PhD, Department of Orthopaedics, Uppsala, Sweden

Introduction: During the last decades several experimental and some clinical studies have described that low-intensity ultrasound applied daily at a fracture site will accelerate the bone healing in both nonunions and fresh fractures. In the last years two placebo-controlled clinical studies have been published describing a reduced healing time for cast-treated diaphyseal tibial fractures (Heckman et al. JBJS 1994;76-A:26-34) as well as for fractures of the distal radius (Kristiansen et al. JBJS 1997;79-A:961-973) following daily use of low-intensity ultrasound.

Purpose: In the present study we wanted to find out whether low-intensity ultrasound will accelerate the healing of fresh tibial fractures when treated with intramedullary fixation.

Patients and Methods: 32 adult patients with a diaphyseal closed or open grade I tibial fracture treated with a reamed and statically locked intramedullary nail (AO Universal) were included. Patients were excluded if radiographs showed severe comminution, if the patient had sustained multiple fractures or other injuries. The study was prospective, randomized, double-blind and placebo-controlled. All patients were equipped with a coded ultrasound (US) device. US started within three days after surgery consisting of 20 minute sessions every day for 75 days. All devices were identical except that only half of the devices emitted an active ultrasound signal. Neither the patient nor the investigator was aware of the status of the device. Codes were not broken until all radiographic reviews had been completed. After surgery the patients were followed every third week until healing and at 26 and 52 weeks. At each visit standardized radiographs were taken. Furthermore, at each visit serum samples were obtained for analysis of serum markers for bone resorption (ICTP) and bone formation (bALP and osteocalcin).

Results: All fractures healed. The average time until the first callus could be seen on the radiographs was 39f3 days for the ultrasound group and 37f3 days for the placebo group. The average healing time defined as bridging of three cortices was 155f22 days (median 112 days) in the ultrasound group while 125f11 days (median 114 days) in the placebo group. The shorter healing time in the placebo group was not significant.

All three serum markers increased for all patients with ICTP reaching a maximum at 1-4 weeks and bALP and osteocalcin at 10-16 weeks. At 1 week the level of ICTP was significantly lower in the ultrasound group compared with placebo. There was no significant difference in the levels of bALP and osteocalcin at any time point between patients treated with ultrasound and placebo.

Discussion: The present study did not show any reduced healing time following ultrasound stimulation. Our findings are not in accordance with previous studies reporting considerable reduction of the healing time of nonoperatively treated fractures. The serum bone markers indicated that ultrasound might slow down early bone resorption while there was no effect of ultrasound on bone formation as given by serum markers. Considering the disagreement in results when compared with the previous study on cast-treated tibial fractures by Heckman et al. the most obvious difference between the studies is the type of treatment. Intramedullary fixation as applied in the present study includes several steps, such as reaming, that might influence the healing process. It is interesting to note that both the placebo- and ultrasound-treated fractures in the present study had an average healing time that was close to the healing time of the ultrasound-treated fractures in Heckmans study, while the placebo group in their study had a significantly longer healing time.

Conclusion: Ultrasound did not shorten healing time in fresh tibial fractures treated with a reamed and statically locked intramedullary nail. Considering the results with reduced healing time of cast-treated fractures in two previous studies, it is important to limit the conclusion of the present study to the specific type of fracture studied and to the specific surgical treatment used.