Can the use of femoral notch view alone decrease measurement error of distal interlocking screws after retrograde femoral nailing
Introduction
Knee pain following intramedullary nailing of the femur is not uncommon with its incidence as high as 86% and 37% with retrograde and antegrade approach respectively [[1], [2], [3], [4], [5], [6], [7], [8]]. The most common causes of knee pain from retrograde intramedullary nailing are related to soft tissue irritation often resulting from the protrusion of distal interlocking screws [3,6,7]. This often leads to additional surgical procedures to remove symptomatic implants leading to a significant healthcare and economic burden [9].
The posteroanterior (PA) view of the knee is often used to confirm final distal interlocking screw position. This technique is fraught with difficulties due to the trapezoidal shape of the distal femur, with the anterior surface being narrower than the posterior surface. As a result, screws that appear to be of appropriate length are in fact prominent. Imaging techniques other than PA imaging may help improve the accuracy of measurement however, little work has been conducted to assess alternative imaging. [10]
Improvement in the accuracy of screw placement has potential to decrease rates of symptomatic implant removal after retrograde femoral nailing. The purpose of this study was to determine if different fluoroscopic views of the knee (Notch or Tangential) could improve the accuracy of radiographic screw length assessment.
Section snippets
Cadaver preparation
Four cadaveric lower limb specimens (2 left, 2 right) were used to simulate retrograde femoral nailing surgical procedures. Cadaveric specimens were free from any history of trauma or deformity of the bony structure and soft tissues in the lower extremity. Using manufacturer recommended techniques, 4 retrograde femoral nails (T2 Retrograde Femoral Nail, Stryker, Kalamazoo, MI, USA) were inserted. Only the most distal interlock was utilized to ensure that the distal interlocking screw was placed
Results
Not all participants completed the survey. The resident cohort answered on average more questions than faculty, 33.91 ± 5.15 questions vs faculty 29.82 ± 11.81 questions (P < 0.016).
Respondents were able to detect overall screw length discrepancies most accurately using the femoral notch view compared to using the PA view (Odds Ratio [OR] 1.26; 95% confidence interval [CI]: 1.07–1.47; P < 0.005) (Table 2). When the images were stratified according to their corresponding screw length, our cohort
Discussion
Despite knee pain from prominent hardware in retrograde nailing being common, little research has focused on ways to prevent this complication. This is surprising, considering that up to 12–37% of patients elect to undergo hardware removal [8,13]. One would hope that good surgical technique with proper measurement and radiographic confirmation would help prevent this complication. However, measurement utilizing depth gauges can be confounded by interposed soft tissue. Intraoperatively
Conflict of interest statement
Boshen Liu, David Zuelzer, Jerad Allen, Shea Comadoll, and Eric Swart have nothing to disclose.
Joseph Hsu was a paid presented/speaker for Smith and Nephew. He is also a board or committee member of the Limb Lengthening Research Society. The terms of these arrangements have been reviewed and approved by Carolinas Medical Center in accordance with its policy on objectivity in research.
Paul Matuszewski receives research support from Stryker. The terms of this arrangement have been reviewed and
Acknowledgements
Cadavers and nails utilized in this investigation were provided in-kind by Stryker Orthopaedics.
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