Posteromedial bowing of the tibia: a benign condition or a case for limb reconstruction?

Lengthening in congenital posteromedial bowing of tibia: a follow-up series at skeletal maturity

PURPOSE

Congenital posteromedial bowing (CPMB) of tibia is a rare, usually self-resolving condition that is present at birth. The data on the long-term outcome of lengthening, choice of fixator, outcome in early and late age groups, and complications is sparse, hence the need for this study.

METHODS

This retrospective study included 93 patients with 94 affected legs from 1991 to 2023. The patients were categorized into early (under 10 years) and late (10 years or above) intervention groups. Eighteen patients with nineteen lengthening episodes who attained skeletal maturity made the basis of this study and will be discussed in detail.

RESULTS

The outcome for the lengthening group at maturity was satisfactory, with 5.53 cm of average length gained per lengthening episode, a mean LLD of 0.31 cm at final follow-up, a mean age of 23.63 years (range 14-38 years), and an average follow-up of 12.51 years (range 3-28 years) post-lengthening, but the procedure was associated with difficulties like ankle stiffness, tibial valgus, pin tract infections, and fractures through regenerate.

CONCLUSION

This study represents a large single-centre series on CPMB. We recommend that surgery for lengthening should be done at an older age, close to skeletal maturity, wherever possible to reduce the risk of repeat lengthening procedures. Based on our experience, we recommend the use of a circular fixator. Uniplanar distractors should have an adequate number and spread of Schanz screws in each segment to reduce the risk of valgus malalignment of distracting segments of bone.

Is the High Healing Index a Complication of Progressive Long Bone Lengthening? Observations from a Cohort of 178 Children Treated with Circular External Fixation for Lower Limb Length Discrepancy

The use of external fixators (EFs) for lower limb lengthening is common for treating lower limb length discrepancy (LLD) in children. The concern at present revolves around extended treatment times, with some suggesting a healing index (HI) > 45 days/cm as a major complication. The aim of this study is to assess the factors affecting bone healing and treatment duration in children who undergo limb lengthening for LLD using circular EFs. A total of 240 lengthening procedures on 178 children affected by congenital or acquired LLDs (mean age at surgery 13.8 ± 2.8 years) were retrospectively evaluated. Complications according to Lascombes' classification and treatment duration factors were analyzed. Mean HI was 57 ± 25 days/cm for the femur and 55 ± 24 days/cm for the tibia, with an HI > 45 days/cm in 64% of the procedures. A total of 189 procedures (79%) reported complications; 85 had an HI > 45 days/cm as the sole complication. While reducing the frame time is crucial, revising the classifications is necessary to avoid the overestimation of complications.

Congenital Posteromedial Bowing of Tibia: Comparison of Early and Late Lengthening

BACKGROUND

Congenital posteromedial bowing of tibia (CPMBT), a rare anomaly, is characterized by a decreasing deformity and a gradually increasing limb shortening. Lengthening in CPMBT has not been studied extensively. Our series compares the duration and complications of lengthening in younger versus older children to determine early lengthening safety and benefits.

METHODS

We studied 28 tibial lengthenings performed by a single surgeon in 23 patients, divided into 2 equal groups of 14 segments: group A 5 years or younger (preschool) and group B above 5 years. All were lengthened with circular external fixators, of which 3 were lengthened over a nail. We measured preoperative (bo) and postoperative (po) sagittal, coronal, and oblique plane deformities, initial limb length discrepancy (LLD), percentage LLD (% LLD), amount of lengthening (AmtL), percentage lengthening (%L), external fixator duration (EFD), and external fixator index (EFI). We graded complications by Lascombes' criteria, results by Association for the Study and Application of the Methods of Ilizarov bone score.

RESULTS

The mean age was 8.8±7.1 years; the mean follow-up was 7.9 years. Group A had significantly greater bo-sagittal, coronal, and oblique plane deformities. Mean LLD (3.4 cm in group A vs. 4.1 cm in group B) was similar in both. Expected LLD at maturity (LLDM) using the multiplier method was greater than previously reported (mean, range in group A: 7.2 cm, 4.4 to 9.5 cm; group B: 5 cm, 2.5 to 9.7 cm). Though AmtL (3.5 and 4.1 cm) was similar in both, %L was 24% in group A and 15.7% in group B (P=0.002). EFD (116.6 days) and EFI (33.7 days/cm) were lesser in group A compared with group B (200.3 days, P=0.001; 50.2 days/cm, P=0.01). Lascombes' triple contract was fulfilled in 11/14 lengthenings in group A versus 3/14 in group B. Association for the Study and Application of the Methods of Ilizarov bone score was good and excellent in both groups (P=0.44).

CONCLUSIONS

In a large series of lengthenings in CPMBT, we found younger children presenting with large deformities and large projected length discrepancies could be safely lengthened with significantly lesser EFD and complications than in older children.

LEVEL OF EVIDENCE

Level IV-therapeutic study.

Posteromedial tibial deformity: Radiological evolution and treatment of the discrepancy

INTRODUCTION

Postero-medial deformity (DMPT), unlike other congenital forms that affect the tibia, presents a good evolution spontaneously correcting the important misalignments that present at birth based on the classic orthopedic laws of Wolff and Hueter-Volkmann, leaving slight residual angulations and variable limb length discrepancy.

MATERIAL AND METHODS

Authors carry out a retrospective review of cases diagnosed with DPMT, the evolution of the tibial angulation and the discrepancy in the length of fourteen patients (11 males and 3 females) followed and treated between the years 2003 and 2018. Seven of these were treated by callus distraction. We have considered: PA and lateral of the tibia and stand-up entire limbs x-ray during age growth, along with the clinical records of the patients.

RESULTS

The medial diaphyseal radiological deformity of the newborn or neonatal period was 34° and the final 10°. The posterior deformity evolved from 46° to a final angulation of 11°. The physeal angulation in the initial AP projection was 34° and the end view was 8° and in the lateral projection from 44 to 6°. The mechanical axis of the limb was correcting towards a neutral axis in relation to the aforementioned physeal and diaphyseal correction in all cases except two. In five of the cases, although the mechanical axis was normal-aligned, at the tibial level it ran eccentrically and externally to the tibial cortex. The length relationship between the short tibia and the healthy tibia maintains a constant proportion throughout the growth of 89%, that is, the inhibition of growth is 11%. We observe that 80% of the discrepancy is found in the tibia and that the remaining 20% ??was exposed from the height of the tarsus. Two patients presented a traumatic and accidental diaphyseal fracture of the tibia. The difference in the length of the tibia was compensated to seven patients by callus distraction of 5.4cm using the callotasis method with a Healing Index of 34.5 days/cm.

CONCLUSIONS

DPMT improves substantially during the first years of life. Joint alignment of the knee and ankle is achieved before the correction of diaphyseal deformity. The tibia length discrepancy increases with the growth of the child since there is an 11% growth inhibition that will cause a skeletal maturity discrepancy between 4-7cm. Callus distraction before skeletal maturity is the method chosen to compensate this discrepancy.

Limb lengthening in the treatment of posteromedial bowing of the tibia

PURPOSE

Posteromedial bowing of the tibia is an uncommon but recognized congenital lower extremity deformity in children that can lead to limb length discrepancy (LLD) and residual angulatory deformity. The purpose of this study is to report a series of children at a single institution with posteromedial bowing treated by lengthening.

METHODS

A retrospective review was carried out at our institution identifying 16 patients who were treated with limb lengthening for posteromedial bowing of the tibia and followed to skeletal maturity. Projected LLD was a mean of 7.7 cm (range 5.0 cm to 14.2 cm). Three patients were treated in a staged fashion with lengthening and deformity correction at age three to four years and subsequent definitive tibial lengthening. The remaining 13 patients were treated with limb lengthening approaching adolescence using circular external fixation.

RESULTS

All patients were pain free and ambulated without a limp at final follow-up. The mean final LLD was 0.3 cm short. In spite of correction of distal tibial shaft valgus in 11 of the 16 patients, eight of the 16 (50%) required later correction of persistent, symptomatic ankle valgus by either hemiepiphyseodesis (seven patients) or osteotomy (one patient).

CONCLUSIONS

Children with posteromedial bowing of the tibial with projected LLD over 5cm can be effectively treated with lengthening. Patients with severe valgus of more than 30° of shaft valgus and difficulty ambulating at age three years can be successfully treated with a two-stage lengthening procedure. Attention should be paid in patients with posteromedial bowing to ankle valgus.

LEVEL OF EVIDENCE

IV.

Deformity progression in congenital posteromedial bowing of the tibia: a report of 44 cases

BACKGROUND

congenital posteromedial bowing of tibia (CPMBT) is a very rare birth defect, characterized by shortened bowed leg and ankle deformity. We described a single institution experience in the management of CPMBT.

METHODS

we identified 44 CPMBT in 44 children. The age at presentation was 5.5 ± 5.6 years and the mean age at the final review was 10.1 ± 4.8 years. Radiographic evaluation included the antero-posterior and lateral inter-physeal angle (AP-IPA and L-IPA), the limb length discrepancy (LLD), the morphology of the distal tibia and the lateral distal tibial angle (LDTA). During the study period, 26 children underwent surgical treatment.

RESULTS

the estimated curves showed a progressive spontaneous correction of both AP-IPA and L-IPA during growth, but a progressive increase of the LLD. The L-IPA showed a more predictable behaviour while the AP-IPA showed a scattered correction, with a wider variation of the estimated final angle. The final LDTA was 85.3° ± 4.2° and was correlated with the L-IPA (r = 0.5; p = 0.02). Among the 26 children who underwent surgical treatment, 23 cases had limb lengthening, 1 case had contralateral epiphysiodesis, 1 child underwent tibial osteotomy, 1 patient was treated by hemiepiphysiodesis of the distal tibia to correct ankle valgus deformity.

CONCLUSIONS

our study described the largest case series of CPMBT. A combination of surgical treatments, in a staged surgical process, should be tailored to the developmental characteristics of this abnormality. An experience-based algorithm of treatment is also proposed. Further studies are needed to understand which is the best strategy to correct this deformity during childhood.

LEVEL OF EVIDENCE

level IV prognostic study.