Miscorrection in coronal plane osteotomies around the knee-Current concepts

This review seeks to clarify and enhance our current understanding around miscorrection following osteotomy surgery around the knee. Whilst many of the principles described also extend to surgery performed for axial and sagittal plane deformity they are mainly predicated on the larger scientific and experiential base which exists in osteotomy for varus and valgus deformity. Miscorrection is not, however, simply the failure to achieve an accurate correction target in the coronal plane but also incorporates a large, interrelated matrix of factors some of which have greater effect than others. Scrutiny of the scientific literature and expert consensual information from two recent European projects facilitates a comprehensive overview of multiple factors in planning, surgical technique and rehabilitation with the current methods employed towards the prevention of miscorrection. The relevance of factors in planning including the level(s) of correction, Joint Line Convergences Angle and Joint Line Obliquity are analysed. Techniques which have evolved to reduce miscorrection include comparison between computer assisted navigation (CAS) and patient-specific instrumentation (PSI) technologies. The use of hinge wire protection in tibial and femoral osteotomy and fixation techniques is considered. The article attempts to clarify the various definitions around the subject with specific attention to the concepts of target, surgical accuracy, accuracy range and tolerance. The realisation that no one target for coronal correction befits all disease processes is mirrored by an understanding that individualised planning is relevant for every patient and depends on many parameters of which some await scientific investigation. The article therefore highlights areas where greater research is required and endorses the growth of Artificial Intelligence and its various domains which may help to 're-process' historic research in addition to helping to design and direct future investigation. LEVEL OF EVIDENCE: Level V.