Kenji Uehara

Effects of timing of low-intensity pulsed ultrasound on distraction osteogenesis

We investigated the effects of low‐intensity pulsed ultrasound (LIPUS; 30 mW/cm2 spatial and temporal average) on the timing of LIPUS treatment in distraction osteogenesis. Lengthening of the right tibia was performed in 75 male Japanese white rabbits using unilateral fixators (waiting period, 7 days; distraction rate, 1.5 mm/day; distraction period, 7 days). Rabbits were divided into four groups according to the timing of the LIPUS treatment. Control group had no stimulation. Waiting group was treated with a daily 20‐min session of LIPUS during a 7‐day latency period. Lengthening group was treated during the lengthening period. Maturation group was treated for the first 7 days after completion of distraction. We evaluated the distraction site by radiography and histology every week for 4 weeks. Bone mineral density (BMD) and mechanical strength were tested and microfocus X‐ray computed tomography was performed on specimens 2 weeks after completion of distraction. The lengthening group had greater BMD and mechanical strength than the other groups, bone regeneration was enhanced more in the maturation group than in the control or waiting groups. Histologically, endochondral bone formation in the lengthening and the maturation groups occurred earlier than in the control or waiting groups. These results suggest the LIPUS effect is mediated via endochondral pathways. We concluded that LIPUS stimulates bone formation in distraction osteogenesis and is most effective during the lengthening phase.

Deformity correction followed by lengthening with the Ilizarov method.

Deformity combined with shortening of 18 lower limb segments of 17 patients was treated with the Ilizarov method. Limb lengthening was done at the same treatment (monofocal treatment) or a separate osteotomy (bifocal treatment) was done after acute or gradual correction of the deformity using the Ilizarov hinge system. The external fixation time, amount of deformity correction, length gained, and incidence of complications were examined. Results were compared between monofocal versus bifocal treatment groups and between femoral versus tibial procedures. The average deformity corrected was 22.3°, and the average lengthening was 44.4 mm. The external fixation index was 49.3 days/cm on average, ranging from 24.4 to 90 days/cm, and the mean duration of external fixation was 198 days, ranging from 77 to 352 days. Major complications requiring surgical treatment, such as premature consolidation and fracture, were seen in four patients. There were no statistically significant differences between the results for monofocal and bifocal treatment or treatment indices for femoral and tibial operations. The Ilizarov method was very effective for treatment of limb deformity combined with shortening. Monofocal treatment might be better if the total amounts of lengthening required are short to reduce surgical invasion. Longer treatment indices for tibial operations could not be verified from the current study.

Cannulation of simple bone cysts

We describe a consecutive series of 26 patients with simple bone cysts who were treated by curettage, multiple drilling and continuous decompression by the insertion of either a cannulated screw or a pin. In the first 15 patients we used titanium cannulated screws (group 1) and in the next 11 a cannulated hydroxyapatite pin (group 2). Satisfactory healing was achieved in 12 patients in group 1 (80%) and in all in group 2. This technique seems to be a promising option for the treatment of simple bone cysts. The cannulated hydroxyapatite pin is recommended because of its higher success rate and the fact that it does not need to be removed.

Minimal curettage, multiple drilling, and continuous decompression through a cannulated screw for treatment of calcaneal simple bone cysts in children.

This report concerns a series of 12 patients with simple bone cysts of the calcaneus, who were treated between 1988 and 2000 by a minimal surgical intervention of curettage, multiple drilling and continuous decompression through insertion of a cannulated screw. Inserted screws were made of titanium in 8 cases and ceramics in 4 cases. The mean operative time was 58.8 ± 25.4 minutes, and complete healing was achieved in 11 cases after 9.2 ± 6.4 months. One patient needed an additional surgery for replacement of a titanium screw. Final results were excellent after a mean follow up of 91 ± 52.1 months. This series of patients represents one of the largest reported series of calcaneal simple bone cyst in conjunction with long-term follow-up. Our technique of minimal curettage, drilling and continuous decompression with a cannulated screw insertion is considered to be a good option for management of simple bone cysts of the calcaneus.