2025 ISAKOS Biennial Congress ePoster
Posterior Tibial Slope In The Paediatric Population - What Is Normal And How Reliable Is Radiographic Measurement?
Dominic Patrick O'Dowd, MBChB, BSc(SEM), MSc(SEM), FRCS(Tr&Orth), Sheffield UNITED KINGDOM
Robert Alex Fawdry, MBChB, MRCS, Sheffield UNITED KINGDOM
Rizwan Arshad, MBChB, FRCS(Tr&Orth), Sheffield UNITED KINGDOM
Kai Sampson, Pending MBChB, Hinckley, Leicestershire UNITED KINGDOM
Sheffield Children's Hospital, Sheffield, South Yorkshire, UNITED KINGDOM
FDA Status Not Applicable
Summary
Posterior tibial slope correction during ACL reconstruction is gaining popularity within the adult literature but at present we have no data within the paediatric population to determine normal tibial slope or justify potential correction
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Abstract
Background
Increased posterior tibial slope (PTS) is associated with a higher risk of anterior cruciate ligament (ACL) injury, including ACL re-rupture. ACL injury in the paediatric population is a common injury with an increasing incidence. PTS is routinely measured on plain radiographs and in the adult population there are established normal ranges from large population studies. In the paediatric population, data is much more limited. A few studies in the skeletally immature have associated increased PTS with tibial spine fractures and ACL ruptures. However, normal ranges for PTS do not appear within the literature for the paediatric population. This poses two key questions; is PTS the same in the skeletally immature population and can the PTS be reliably measured on radiographs in the skeletally immature?
Methods
146 skeletally immature patients between the ages of 3 and 17 years old with knee radiographs were reviewed. Key demographic data including age, gender and laterality was recorded. Those with underlying medical conditions that may affect development of the knee or lower limb were excluded. Radiographs were reviewed by the lead investigator to determine an appropriate image for measurement. PTS angle was measured using the posterior cortex method by 3 investigators who were blinded to each other’s results. PTS angles for each age were calculated and inter-observer reliability was assesed.
Results
Knee radiographs of 146 patients underwent initial review, with 30 subsequently excluded. The mean PTS angle was 6.25° (SD 3.85°, range -8.1°–17.4°). Comparing PTS angle across ages 3-17 years of age we found a positive correlation (R2 0.2652). This reduced to a smaller positive correlation between the ages of 5-17 years old (R2 0.0310). In patients aged 3-7 years old, measurement of PTS angle demonstrated poor inter-observer reliability (ICC 0.389504). Good inter-observer reliability occurred when measuring PTS angle in patients between 8-17 years old (ICC 0.809556).
Conclusion
Posterior tibial slope is an important consideration in knee injuries. Our study reports PTS angle in skeletally immature patients to be similar to that reported in the literature for the adult population. We found poor inter-observer reliability when measuring PTS angle on radiographs in patients aged 7 years old and younger. MRI may be a more reliable tool for measuring PTS angle in younger patients where limited ossification has occurred.