title: Malrotation deformities of the lower extremity and implications on total knee arthroplasty: a narrative review.
abstract: BACKGROUND
  Total knee arthroplasty (TKA) is a successful procedure for the management of osteoarthritis (OA) of the knee. Axial plane deformities are more common than suspected in patients presenting with osteoarthritis of the knee joint. Recent research has indicated that torsional deformities could play an important role in the development of anterior knee pain (AKP).
  
  
  METHODS
  In a narrative review of the literature, the aetiology of maltorsion deformity of the lower extremity in both, childhood and adulthood, as well as the development of postoperative femoral axial plane deformities are examined. This includes the numerous surgical interventions that have been described for the treatment of maltorsion syndrome, and the role of patient-specific instrumentation. Finally, correcting for maltorsion deformity during and its potential implications for the current clinical care pathway, in terms of both pre- and perioperative practices is discussed.
  
  
  CONCLUSIONS
  Axial plane alignment is considered the 'third dimension' in TKA. Correct axial alignment the lower extremity and of prosthetic components is deemed an important prerequisite for a postoperatively stable and painless knee. Identification of and, where appropriate, adjustment for any pre-existing maltorsion deformities is thought to significantly reduce the proportion of patients with residual complaints following TKA. Well-designed and well-conducted clinical studies are required to support our hypotheses.
authors.affiliation: Department of Orthopaedic Surgery, Ziekenhuis Netwerk Antwerp, Campus Stuivenberg, Antwerp, Belgium. geert.peersman@telenet.be.
authors.forename: Geert
authors.initials: G
authors.lastname: Peersman
authors.affiliation: Department of Orthopaedic Surgery, Ziekenhuis Netwerk Antwerp, Campus Stuivenberg, Antwerp, Belgium.
authors.forename: Kim
authors.initials: K
authors.lastname: Taeymans
authors.affiliation: Department of Orthopaedic Surgery, Ziekenhuis Netwerk Antwerp, Campus Stuivenberg, Antwerp, Belgium.
authors.forename: Christophe
authors.initials: C
authors.lastname: Jans
authors.affiliation: Department of Orthopaedic Surgery, Ziekenhuis Netwerk Antwerp, Campus Stuivenberg, Antwerp, Belgium.
authors.forename: Philippe
authors.initials: P
authors.lastname: Vuylsteke
authors.affiliation: AMR Advanced Medical Research, Hofenstrasse 89b, 8708, Männedorf, Switzerland.
authors.forename: Peter
authors.initials: P
authors.lastname: Fennema
authors.affiliation: Department of Orthopedics and Rheumatology, University Hospital Marburg, 35043, Marburg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Heyse
mesh_terms: D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D017760:Bone Malalignment / Q000175:diagnosis / Q000601:surgery*; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D035002:Lower Extremity / Q000601:surgery*; D011184:Postoperative Period; D011859:Radiography
keywords: Anterior knee pain; Malrotation; Osteoarthritis; Patient-specific instrumentation; Total knee arthroplasty