Open AccessThe ischiofemoral space of the hip is influenced by the frontal knee alignment
Author(s) -
Ahmad Sufian S.,
Kerber Vincent,
Konrads Christian,
Ateschrang Atesch,
Hirschmann Michael T.,
Stöckle Ulrich,
Ahrend Marc D.
Publication year - 2021
Publication title -
knee surgery, sports traumatology, arthroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.806
H-Index - 125
eISSN - 1433-7347
pISSN - 0942-2056
DOI - 10.1007/s00167-021-06589-6
Subject(s) - lesser trochanter , medicine , pelvis , femur , ischium , osteotomy , ischial tuberosity , ankle , tibia , greater trochanter , orthodontics , radiography , reduction (mathematics) , anatomy , surgery , mathematics , geometry
Purpose The ischiofemoral distance (IFD), defined as the distance between the ischial tuberosity and the lesser trochanter of the femur, is gaining recognition as an extra‐articular cause of hip pain. It is unknown whether the IFD is influenced by the frontal knee alignment. The aim of this study was to determine the influence of realignment surgery around the knee on the IFD. It was hypothesized that valgisation osteotomy around the knee is associated with reduction of the IFD. Methods A consecutive series of 154 patients undergoing frontal realignment procedures around the knee in 2017 were included in this study. Long‐leg standing radiographs were obtained before surgery and postoperatively. The IFD was measured between the ischium and the lesser trochanter at three different levels (proximal, middle and distal margins of the lesser trochanter parallel to the horizontal orientation of the pelvis) on standardized long‐leg radiographs with the patient in upright standing position. The knee alignment was determined by measuring the hip knee ankle angle, mechanical lateral distal femur angle and the medial mechanical proximal tibia angle. Linear regression was performed to determine the influence of the change of frontal knee alignment on the IFD. Results Linear regression showed a direct influence of the overall change in frontal knee alignment on the IFD of the hip, regardless of the site of the osteotomy (β‐0.4, confidence‐interval − 0.5 to − 0.3, p < 0.001). Valgisation osteotomy around the knee induced a significant reduction of the ipsilateral IFD ( p < 0.001), while varisation osteotomy induced a significant increase ( p < 0.001). The amount of ISD change was 0.4 mm per corresponding degree of change in frontal knee alignment. Conclusion These findings are relevant to both the hip and knee surgeons when planning an osteotomy or arthroplasty procedure. Correction of a malalignment of the knee may resolve an ischiofemoral conflict in the hip. The concept deserves inclusion in the diagnostic workup of both the hip and knee joints. Level of evidence IV.