ORIGINAL ARTICLE Haydar A. J. Al Hussainy Æ Asem Deeb Awani K. Choudhary Æ Charles R. Merrill Can we obtain an accurate sagittal plane bony entry point in the assessment of tibial intramedullary nailing radiographs? Received: 23 March 2005 / Accepted: 6 June 2005 / Published online: 1 September 2005 Ó Springer-Verlag 2005 Abstract The objective of this invitro study is to test and describe a new method of obtaining accurate sagittal plane bony entry point after tibial nailing using lateral projection radiograph without having to standardise the radiographic technique. Radiopaque markers were fixed to the anterior oblique facet of the proximal tibial me- taphysis of ten synthetic tibiae between the articular surface and the tibial tubercle to simulate the intrame- dullary nailing bony entry point. Controlled standar- dised lateral radiographs were obtained in three different axial rotations. The 30 resultant radiographs were scrutinised for precise bony entry points: ‘C’ which represents the percentage of ratio of the distance be- tween articular surface and the radio opaque marker ‘A’, to the distance between the articular surface and the tibial tubercle ‘B’. The Mean deviation in ‘C’ values from the true lateral was 0.4% in 15 ° internal rota- tion, 0.6% in 15 ° external rotation. None was statis- tically significant. Axial rotation has no significant effect on accuracy of sagittal plane bony entry point mea- surement in lateral radiographs. Precise bony entry point can be obtained using the method described without having to standardise lateral projection radio- graphs. Keywords Invitro Æ Bony entry point Æ X-ray Æ Intramedullary nailing Æ Tibial shaft Æ Fracture Radiographie de profil du point d‘entre´e de l’enclouage du tibia Re´ sume´ Le but de ce travail in vitro est de tester et de de´crire une nouvelle me´thode pour obtenir la visualisa- tion de profil du point d’entre´e d’un clou tibial. Des repe`res radioopaques ont e´te´ place´s sur 10 os synthe´- tiques entre la surface articulaire et la tube´rosite´ tibiale ante´rieure pour simuler le point d’entre´e du clou. Les radiographies de profil ont e´te´ re´alise´es dans 3 rotations diffe´rentes. A partir des 30 radiographies ont e´te´ obte- nues les valeurs de A (distance entre la surface articulaire et le point d’entre´e), de B (distance entre la surface ar- ticulaire et la tube´rosite´ tibiale ante´rieure) et C (rapport A/B en%). Par rapport a` la valeur du profil strict, la valeur de C sur les cliche´s en rotation interne est de 0,4% et sur les cliche´s en rotation externe de 0,6%. Ces diffe´rences ne sont pas statistiquement significatives. Les auteurs concluent que la rotation n’a pas d’effet sur le repe´rage du point d’entre´e de profil et qu’il n’est donc pas ne´cessaire de recourir a` une technique radiologique standardise´ e. Mots cle´s Invitro Æ point d’entre´ e Æ radiographie Æ enclouage centrome´ dullaire Æ diaphyse tibiale Æ fracture Introduction Extra-articular tibial shaft fractures are commonly treated by intramedullary nailing [1, 5, 7, 8, 14, 20, 21]. The high frequency of chronic anterior knee pain [1, 7, 9–13, 15, 17, 22, 24] following this procedure has led many to search for the possible aetiology [16, 18, 19, 23]. H. A. J. Al Hussainy Department of Trauma & Orthopaedic surgery, Northern General Hospital, The University of Sheffield, Herries Road, Sheffield, UK A. K. Choudhary Æ A. Deeb Department of Trauma & Orthopaedic Surgery, Bassetlaw District General Hospital, Worksop, Nottinghamshire, UK C. R. Merrill Department of Radiology, Bassetlaw District General Hospital, Worksop, Nottinghamshire, UK H. A. J. Al Hussainy (&) 18 Siskin Court, Gateford, Worksop, Nottinghamshire, S81 8UE, UK E-mail: haydaralhussainy@rcsed.ac.uk Tel.: +44-793-1811213 Eur J Orthop Surg Traumatol (2006) 16: 24–29 DOI 10.1007/s00590-005-0017-4