Osteotomies around the knee lead to corresponding frontal realignment of the ankle

European Journal of Orthopaedic Surgery & Traumatology https://doi.org/10.1007/s00590-021-03016-x ORIGINAL ARTICLE Osteotomies around the knee lead to corresponding frontal realignment of the ankle Christian Konrads1 · Alexander Eis1 · Sufian S. Ahmad1,2 · Ulrich Stöckle2 · Stefan Döbele1 Received: 22 March 2021 / Accepted: 21 May 2021 © The Author(s) 2021 Abstract Introduction Despite the fact that osteotomies around the knee represent well-established treatment options for the redistribution of loads and forces within and around the knee joint, unforeseen effects of these osteotomies on the ankle are still to be better understood. It was therefore the aim of this study to determine the influence of osteotomies around the knee on the coronal alignment of the ankle. We hypothesize that osteotomies around the knee for correction of genu varum or valgum lead to a change of the ankle orientation in the frontal plane by valgisation or varisation. Materials and methods Long-leg standing radiographs of 154 consecutive patients undergoing valgisation or varisation osteotomy around the knee in 2017 were obtained and utilized for the purpose of this study. Postoperative radiographs were obtained after union at the osteotomy site. The hip knee ankle angle (HKA), the mechanical lateral distal femur angle (mLDFA), the mechanical medial proximal tibia angle (mMPTA) and five angles around the ankle were measured. Comparison between means was performed using the Wilcoxon-Mann–Whitney test. Results One hundred fifty-four patients (96 males, 58 females) underwent osteotomies around the knee for coronal realignment. The mean age was 51 ± 11 years. Correction osteotomies consisted of 73 HTO, 54 DFOs, and 27 double level osteotomies. Of all osteotomies, 118 were for valgisation and 36 for varisation. For valgisation osteotomies, the mean HKA changed from 5.8° ± 2.9° preoperatively to − 0.9° ± 2.5° postoperatively, whereas the mMPTA changed from 85.9° ± 2.7° to 90.7° ± 3.1° and the malleolar-horizontal-orientation-angle (MHA) changed from 16.4° ± 4.2° to 10.9° ± 4.2°. For varisation osteotomies, the mean HKA changed from − 4.3° ± 3.7° to 1.1° ± 2.2° postoperatively, whereas the mLDFA changed from 85.7° ± 2.2° to 89.3° ± 2.3° and the MHA changed from 8.8° ± 5.1° to 11.2° ± 3.2°. Conclusion Osteotomies around the knee for correction of coronal limb alignment not only lead to lateralization or medialization of the weight-bearing line at the knee but also lead to a coronal reorientation of the ankle. This can be measured at the ankle using the MHA. When planning an osteotomy around the knee for correction of genu varum or valgum, the ankle should also be appreciated—especially in patients with preexisting deformities, ligament instabilities, or joint degeneration around the ankle. Keywords Deformity · Osteotomies · Realignment · Valgisation · Varisation Abbreviations aLDTA Anatomic Lateral Distal Tibia Angle AMA Anatomic Mechanical Angle of the femur HKA Hip Knee Ankle angle JLCA Joint line conversion angle mTFA Mechanical tibio-femoral angle * Christian Konrads 1 Department for Trauma and Reconstructive Surgery, BG Klinik, University of Tübingen, Tübingen, Germany 2 Center for Musculoskeletal Surgery, Charité - University Medical Center Berlin, Berlin, Germany mLDFA Mechanical Lateral Distal Femoral Angle mLPFA Mechanical Lateral Proximal Femoral Angle mMPTA Mechanical Medial Proximal Tibial Angle aLDTA Anatomic Lateral Distal Tibia Angle mLDTA Mechanical Lateral Distal Tibia Angle mMA Mechanical Malleolar Angle MHA Malleolar Horizontal Orientation Angle SD Standard Deviation TPHA Tibia Plafond Horizontal Orientation Angle TTTA Tibio Talar Tilt Angle 13 Vol.:(0123456789) European Journal of Orthopaedic Surgery & Traumatology Introduction Osteotomies around the knee represent powerful modalities for the treatment of bony deformities and degenerative joint disease [1–4]. The intended effects of these osteotomies act on joints by redistributing loads and force vectors [5, 6]. Despite the fact that osteotomies around the knee represent well-established treatment options for the redistribution of loads and forces within and around the knee joint, unforeseen effects of these osteotomies on the ankle are still to be better understood. Although osteotomies around the knee are successful orthopaedic standard procedures, it is not known to what extent coronal ankle alignment might be intentionally or unintentionally altered. It was therefore the aim of this study to determine the influence of osteotomies around the knee on the coronal alignment of the ankle. We hypothesize that osteotomies around the knee for correction of genu varum or valgum lead to a change of the ankle orientation in the frontal plane by valgisation or varisation. This new knowledge would help to treat patient better by improving the planning of osteotomies and avoiding unwanted effects on the adjacent ankle joint. Patients and methods The patient cohort included 154 knees of 154 patients undergoing osteotomies around the knee due to bony malalignment and corresponding symptoms. The mean age was 51 ± 11 years. There were 96 male and 58 female patients. All osteotomies performed were around the knee and included 73 high tibial osteotomies (HTO), 54 distal femur osteotomies (DFO) and 27 double level osteotomies. Of all osteotomies, 118 were valgisation osteotomies and 36 were varisation osteotomies. All consecutive patients were treated in a single center in the year 2017. Patients were excluded, if a multiple plane correction was performed, no magnification device was present on the postoperative radiograph, or image quality was inferior. Considering the above criteria, 154 knees of 154 patients undergoing osteotomy were considered eligible for retrospective data retrieval and inclusion in the study (Fig. 1). Ethical approval was received for the conduction of this study (421/2020BO). All osteotomies were planned using a landmark based deformity analysis [7, 8]. A high tibial osteotomy was performed as described by Staubli and Lobenhoffer using a TomoFix MHT plate fixator (DePuy Synthes, Solothurn, Switzerland) [9–11]. Distal femoral osteotomy was performed using a medial subvastus approach and the technique described by Lobenhoffer [12–14]. For fixation, a TomoFix MDF plate (DePuy Synthes, Solothurn, Switzerland) 13 Fig. 1  Flowchart demonstrating inclusion was used [15]. Double level osteotomy was performed as described by Schröter et al. [16]. Long-leg weight-bearing radiographs were obtained in accordance with Paley using a 1.3 m cassette (Global Imaging Baltimore, MD) [7]. Long leg antero-posterior standing radiographs were obtained with the patient standing in a bipedal stance in front of the long film cassette. The radiography tube was positioned in a distance of 305 cm. The selected film cassette was of sufficient length to include the hips, knees, and ankles. The magnification with this setu (...truncated)