Background: Heel valgus and flattening of arch are common in rheumatoid arthritis (RA). The progression of hindfoot valgus deformity results in pain and debilitating disability, and causes the excessive stress on the ankle joint. Subtalar arthrodesis is often indicated in these cases to reduce the pain and to correct the talocalcaneal alignment. However, accurate correction is not easy without bone grafting, because bone defect often appears after correction. Bone grafting is necessary for accurate correction in these cases, but we have avoided it because of following reasons; donor site problem like insufficiency fractures of pelvis, supply limitation of autograft for possible multiple operations during long term disease progression of RA and the lack of bone graft substitutes, which possesses enough osteoconductivity. Now we have developed the interconnected porous calcium hydroxyapatite (IP-CHA) which possesses good osteoconductivity and achieves major incorporation with host bone much more rapid than the other porous calcium hydroxyapatite. So, we evaluated the usefulness of the packing with the newly developed IP-CHA in bone defect after correction of pes planovalgus deformity of RA patients.
Methods: The best possible correction of talonavivular alignment and fixation is performed using one cubic hydroxyapatite block (1x1x1cm), staple and Kirschner wire. Then granular IP-CHA is implanted in bone defect existing mainly in talar body, gap of talonavicular joint and sinus tarsi. Six planovalgus feet were treated with subtalar arthrodesis in 4 female RA patients (3; triple arthrodesis, 3; subtalar and talonavicular arthrodesis). The average age was 56.8 years. Angle of internal arch (IA), tibiocalcaneal (TC) angle in modified Cobey’s method, talocalcaneal height (TCH) in standing position were assessed on the basis of the radiographies at just before operation and final follow-up (average 17.5 months, range 7 to 25 months).
Results: Mean IA angle was 138.9 degrees pre-operatively and 132.4 at the last follow-up. Mean TC angle was 14.9 degrees pre-operatively and 7.2 at the last follow-up. No collapse or deformity of hydroxyapatite implanted in the bone defect was observed.
Conclusion: Our original technique using IP-CHA was shown to prevent from initial sinking or loss of correction. This technique could make it quit easy to correct the malalignment of talocalcaneal joint with regaining of TCH in painful planovalgus deformity of RA patients.
