Recurrence of axial malalignment after surgical correction in congenital femoral deficiency and fibular hemimelia.

Purpose: Recurrent genu valgum deformity complicates treatment of congenital femoral deficiencies (CFD) and fibular hemimelia (FH). We analysed factors influencing recurrence.
Methods: Patients who underwent limb lengthening or deformity correction for CFD and/or FH were reviewed. Radiographs after surgery and after a minimum of a further six months were analysed. Change in parameters of mechanical axis deviation per month (∆ MAD/month) and of angle per month were calculated. These parameters were tested against cofactors patient age, baseline MAD, type of CFD and FH, severity of ball-and-socket joints, ankle-joint stiffness, absence of cruciate ligaments and resection of the fibular anlage.
Results: Recurrent valgus deformity was found in 23 of the 42 limbs included with a mean change of MAD of 23.4 mm (5-60 mm). There was no significant difference between patients with ∆ MAD/month <0.5 mm versus >1 mm regarding MAD in the first radiograph and patient age. CFD cases Pappas types VII and VIII showed a ∆ MAD/month of 1.6 mm, whereas milder cases of Pappas IX showed a ∆ MAD/month of 0.8. Mild FH (type Ia) showed a mean ∆ MAD/month of 0.39 mm, whereas mean ∆ MAD/month for FH type Ib/II was 0.72 mm. In FH type II cases, mean ∆ MAD/month was 0.79 mm after resection of the fibular anlage compared with 1.98 mm in those without resection.
Conclusions: Recurrence in FH and CFD was not dependent on patient age but partly on FH and CFD type. Limbs with more severe ball-and-socket knee joints showed more recurrence. Overcorrection depending deformity type should be performed.