Miserable malalignment syndrome associated knee pain: a case for infra-tubercle tibial de-rotation osteotomy using an external fixator

Abstract

Introduction: Miserable malalignment syndrome is a complex torsional lower limb deformity with limited consensus on surgical treatment. We present the outcome of de-rotation of the tibia alone using an external fixator.

Methods: Fifteen patients (22 segments) were operated on between 2012 and 2020; 13 presented with anterior knee pain, and two presented with out-toeing. Gait analysis was done in nine patients, and CT scan rotational profile, including tibial tubercle-trochlear groove distance, femoral version, and tibial torsion, were calculated. Kujala knee pain score and visual analogue pain score (VAS) were recorded. All underwent infra-tubercular osteotomy of the tibia and midshaft osteotmy of the fibula and application of a hexapod circular frame to gradually internally rotate the tibia until the foot aligned with the patella.

Results: There was no preoperative clinical or radiographic evidence for patellar instability, femoral anteversion 30° (21°-54°), and external tibial torsion 50° (37-70). The mean age at surgery was 21 years (12-37) with a mean follow-up of 20 months (9-83). All osteotomies healed, and the frames were removed at a mean of 111 days (80-168). The mean VAS score improved from 8(5-9) to 1(0-4) postoperatively (P < 0.001). The mean Kujala knee pain score increased from 53 (30-75) to 92 (54-100) postoperatively (P < 0.001). The mean preoperative foot progression angle (FPA) was 37° (20°-50°), with 13 postoperatively walking with neutral FPA. One patient walked with symmetrical + 10° and the other with - 5° FPA. All patients reported relief of knee pain and were satisfied with the alignment.

Conclusion: Gradual correction of severe external tibia torsion with a hexapod external fixator and an infra-tubercle tibial osteotomy could provide an optimum method to eliminate knee pain and improve limb alignment in miserable malalignment syndrome.

Keywords: Anterior knee pain; External fixator; Femoral anteversion; Miserable malalignment syndrome; Tibia de-rotation; Tibia torsion.