Medial patellofemoral ligament reconstruction combined with biplanar supracondylar femoral derotation osteotomy in recurrent patellar dislocation with increased femoral internal torsion and genu valgum: a retrospective pilot study

(2021) 22:990 Deng et al. BMC Musculoskeletal Disorders https://doi.org/10.1186/s12891-021-04816-2 Open Access RESEARCH Medial patellofemoral ligament reconstruction combined with biplanar supracondylar femoral derotation osteotomy in recurrent patellar dislocation with increased femoral internal torsion and genu valgum: a retrospective pilot study Xiangtian Deng1,2,3, Lingzhi Li2,3, Peng Zhou2,3, Fuyuan Deng2,3, Yuan Li2,3, Yanwei He2,3, Ge Chen2,3, Zhong Li2,3* and Juncai Liu2,3* Abstract Background: The purpose of this study was to evaluate the clinical and radiographic outcomes after medial patellofemoral ligament (MPFL) reconstruction combined with supracondylar biplanar femoral derotation osteotomy (FDO) in recurrent patellar dislocation (RPD) with increased femoral anteversion angle (FAA) and genu valgum. Methods: Between January 2017 to December 2020, a total of 13 consecutive patients (13 knees, 4 males and 9 females, mean age 18.7 (range, 15–29 years) with RPD with increased FAA (FAA > 25°) and genu valgum (mechanical axis deformity of ≥5°) who underwent supracondylar biplanar FDO using a Tomofix-locking plate combined with MPFL reconstruction in our institution were included. Preoperative full-leg standing radiographs, lateral views, and hip-knee-ankle computed tomography (CT) scans were used to evaluate the mechanical lateral distal femoral angle (mLDFA), anatomical femorotibial angle (aFTA), mechanical axis, patellar height, tibial tubercle-trochlear groove (TTTG) distance, and torsional angle of the tibial and femoral in the axial plane. Patient reported outcomes were evaluated using the International Knee Documentation Committee (IKDC) score, Kujala score, Lysholm score, visual analog scale (VAS), and Tegner score preoperatively and postoperatively. Postoperative CT scans were used to evaluate the changes of FAA and TT-TG, and full-leg standing radiographs was used to evaluate the changes of mLDFA, aFTA, and mechanical axis. Results: A total of 13 patients (13 knees) were included with an average follow-up period of 26.7 months (range 24–33). No cases developed wound infection, soft tissue irritation, and recurrent patellar dislocation during the followup period after surgery. Bone healing at the osteotomy site was achieved in all cases, and all patients regained full extension and flexion. Clinical outcomes (VAS, Kujala, IKDC, Lysholom, and Tegner scores) improved significantly at the *Correspondence: ; 3 Sichuan Provincial Laboratory of Orthopaedic Engineering, Department of Bone and Joint Surgery, The Affiliated Hospital of Southwest Medical University, Lu Zhou 646000, Sichuan Province, People’s Republic of China Full list of author information is available at the end of the article © The Author(s) 2021. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativeco mmons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Deng et al. BMC Musculoskeletal Disorders (2021) 22:990 Page 2 of 8 final follow-up after surgery (p < 0.05). The mean mLDFA, aFTA, mechanical axis, and TT-TG distance showed statistically significant improvement following the combined surgery (p < 0.05), while the CDI did not change significantly after surgery (p>0.05). Conclusion: MPFL reconstruction combined with supracondylar biplanar FDO showed satisfactory clinical outcomes and radiographic results in the short-term follow-up period. Keywords: Recurrent patellar dislocation, Genu valgum, Femoral anteversion angle, Femoral derotation osteotomy, Biplanar, Medial patellofemoral ligament reconstruction, Alignment correction Background Recurrent patellar dislocation (RPD) is a complex condition, and multiple contributing factors for patellar instability have been identified, including patella alta, genu valgum, disrupted or weaken medial soft tissue, trochlear dysplasia, increased tibial tuberosity and the trochlear groove (TT-TG) distance, and rotational malalignment of the femur or tibia [1–5]. Specially, osseous deformities in the coronal and axial plane, such as genu valgum and torsional deformities of the lower extremity, are now considered to be associated with adverse effects on patellofemoral instability [6, 7]. Herein, the increased femoral anteversion angle (FAA) and genu valgum are thought to create a sustaining lateralizing force vector applied on the patella, which might increase excessive loading forces on the reconstructed graft and even lead to patellar redislocation [8, 9]. At present, there is still much controversy in the surgical techniques of RPD combined with knee valgus deformity. In recent years, various surgical techniques for addressing RPD with genu valgum have been described [10–12]. Generally, the MPFL is the major stabilizer which restricts lateral patellar displacement from zero to thirty of knee flexion, and MPFL reconstruction has been validated as a reliable surgical procedure for treating recurrent patellar instability. Nevertheless, isolated MPFL reconstruction might not be sufficient in patients with increased femoral anteversion and genu valgum, as it does not address the underlying lateralizing force vector acting on the patella [13]. Although it has been shown that genu valgum combined with excessive femoral internal torsion are primary risk factors for RPD, it is rarely corrected by surgery simultaneously. Despite studies that confirm the association between mechanical malalignment of multi-plane and patellar instability, there is a paucity of studies published regarding clinical and radiographic results after MPFL reconstruction combined with supracondylar biplanar FDO procedure in this population. The purpose of this study was to a) analyze the clinical and radiographic results of the MPFL reconstruction combined with biplanar supracondylar FDO procedure, b) to evaluate the differences between pre- and post-operative knee function and radiographic results including effects on patellar parameters and alignment correction, c) to assess complications associated with bone healing, soft tissue irritation, w (...truncated)