Computer-assisted analysis of lower limb geometry: higher intraobserver reliability compared to conventional method

Exact radiographic evaluation of lower limb alignment, joint orientation and leg length is crucial for preoperative planning and successful treatment of deformities, fractures and osteoarthritis. Improvement of the accuracy of radiographic measurements is highly desirable. To determine the intraobserver reliability of conventional analysis of lower extremity geometry, 59 long leg radiographs were randomly analyzed 5 times by a single surgeon. The measurements revealed a standard deviation between 0.36° and 1.17° for the angles mLPFA, mLDFA, MPTA, LDTA, JLCA and AMA (nomenclature according to Paley), and 0.94 mm and 0.90 mm for the MAD and leg length, respectively. Computer-assisted analysis with a special software significantly reduced the standard deviation of the mLDFA, MPTA, LDTA, JLCA (each p < 0.001), AMA (p = 0.032) and MAD (p = 0.023) by 0.05–0.36° and 0.14 mm, respectively. Measuring time was reduced by 44% to 6:34 ± 0:45 min (p < 0.001). Digital calibration by the software revealed an average magnification of conventional long leg radiographs of 4.6 ± 1.8% (range: 2.7–11.9%). Computer-assisted analysis increases the intraobserver reliability and reduces the time needed for the analysis. Another major benefit is the ease of storage and transfer of digitized images. Due to the varying magnification factors on long leg radiographs, the use of magnification markers for calibration is recommended.

[1]  K S Conn,et al.  A simple guide to determine the magnification of radiographs and to improve the accuracy of preoperative templating. , 2002, The Journal of bone and joint surgery. British volume.

[2]  D. Paley,et al.  Mechanical axis deviation of the lower limbs. Preoperative planning of uniapical angular deformities of the tibia or femur. , 1992, Clinical orthopaedics and related research.

[3]  P. Aichroth,et al.  Radiological study of alignment after total knee replacement , 1991, International Orthopaedics.

[4]  C. Mazel,et al.  [Value of preoperative planning in total hip arthroplasty]. , 2002, Revue de chirurgie orthopedique et reparatrice de l'appareil moteur.

[5]  C. Jiang,et al.  Effect of rotation on the axial alignment of the femur. Pitfalls in the use of femoral intramedullary guides in total knee arthroplasty. , 1989, Clinical orthopaedics and related research.

[6]  G. Engh,et al.  Radiographic assessment of knee alignment after total knee arthroplasty. , 1988, The Journal of arthroplasty.

[7]  S. Goodman,et al.  Preoperative templating for the equalization of leg lengths in total hip arthroplasty. , 1992, Contemporary orthopaedics.

[8]  R. Teitge,et al.  Preoperative planning for the treatment of nonunions and the correction of malunions of the long bones. , 1990, The Orthopedic clinics of North America.

[9]  A R Feinstein,et al.  Measurement of lower limb alignment using long radiographs. , 1991, The Journal of bone and joint surgery. British volume.

[10]  C. Krettek,et al.  Accuracy of intramedullary templates in femoral and tibial radiographs. , 1996, The Journal of bone and joint surgery. British volume.

[11]  E Y Chao,et al.  Biomechanics of malalignment. , 1994, The Orthopedic clinics of North America.

[12]  D I Rowley,et al.  Computerised measurement of tibiofemoral alignment. , 2001, The Journal of bone and joint surgery. British volume.

[13]  J. Wright.  Heterotopic ossification about the hip after intramedullary nailing for fractures of the femur. , 1991, The Journal of bone and joint surgery. American volume.

[14]  J. Moreland,et al.  Radiographic analysis of the axial alignment of the lower extremity. , 1987, The Journal of bone and joint surgery. American volume.

[15]  F. Noyes,et al.  Preoperative planning for high tibial osteotomy. The effect of lateral tibiofemoral separation and tibiofemoral length. , 1992, Clinical orthopaedics and related research.

[16]  M. Dahl.  Preoperative planning in deformity correction and limb lengthening surgery. , 2000, Instructional course lectures.

[17]  K. Swanson,et al.  Does Axial Limb Rotation Affect the Alignment Measurements in Deformed Limbs? , 2000, Clinical orthopaedics and related research.

[18]  T. Young,et al.  Determination of accuracy of preoperative templating of noncemented femoral prostheses. , 1995, The Journal of arthroplasty.

[19]  J. Lonner,et al.  Effect of Rotation and Knee Flexion on Radiographic Alignment in Total Knee Arthroplasties , 1996, Clinical orthopaedics and related research.

[20]  S. Stricker,et al.  Radiographic measurement of bowleg deformity: variability due to method and limb rotation. , 1994, Journal of pediatric orthopedics.

[21]  N. Kadakia,et al.  Inter- and intraobserver variability of radiographic measurements of knee alignment. , 2001, The American journal of knee surgery.

[22]  R H Wade,et al.  Pre-operative planning in orthopaedics: a study of surgeons' opinions. , 1998, Injury.

[23]  FRCSC Dror Paley MD,et al.  Principles of Deformity Correction , 2002, Springer Berlin Heidelberg.