Limb lengthening in congenital posteromedial bow of the tibia

Abstract

Congenital posteromedial bowing of the tibia (PMBT) is a rare condition affecting one lower limb. The bowing of the tibia usually resolves; however, there is associated limb length discrepancy (LLD), which often persists and can cause functional deficits. Advances in limb lengthening techniques allow this issue to be addressed, often with concomitant angular deformity correction. This study examined eleven patients who have had limb lengthening procedures with mean pre-operative LLD of 3.7 cm (range 1.5–5 cm), mean increase in length was 3.9 cm (range 1.5–5.8 cm), and mean LLD at last follow-up was less than 0.6 cm (range 0–2.0 cm). The main complications were minor or moderate grades, such as pin site infection. Greater LLD was found than previously reported, and we believe that the tertiary referrals were those of a severe form of PMBT. The authors conclude that in view of deformity with discrepancy, in select cases, correction and lengthening would be an option rather than only contralateral epiphysiodesis.

Congenital Posteromedial Bowing of the Tibia: A Single Center Experience

“…Bowing was located more frequently in the distal than in the middle third, and posterior angulation was of a greater magnitude than medial bowing. Those findings are similar with other reports (1,2,5). Bowing of tibia is almost uniformly accompanied with calcaneovalgus of various degree (2,7,11).…”

“…Those findings are similar with other reports (1,2,5). Bowing of tibia is almost uniformly accompanied with calcaneovalgus of various degree (2,7,11). Severe calcaneovalgus foot deformity was present in all six of our patients.…”

“…Occasionally, it is diagnosed prenatally by ultrasound as early as at 20 weeks of gestation (1), but in most cases it is diagnosed at birth (2). Etiology and pathogenesis of the anomaly still remains unclear (3).…”

“…However, no relation between shortening and extent of posterior bowing could be demonstrated (6,7). Initial treatment usually consists of a series of the above knee casts, followed by stretching exercises (2,4,8). Correction is maintained by splints or orthosis.…”

“…For a long time, this was the only suggested equalization procedure for CPMBT (4). Later on, limb lengthening procedures that used distraction osteogenesis emerged and gained popularity, regardless of utilized distraction devices (2,5). Persisting angulations of tibia greater than 35 degrees should be surgically corrected with simultaneous limb lengthening procedure, via single or multilevel osteotomies (10).…”