Femoral tunnel enlargement after medial patellofemoral ligament reconstruction is common and can be monitored using plain radiographs

Tobias Roberts; Laura Casey; Diego Abelleyra Lastoria; Samuel Walters; Toby Smith; Caroline Hing

doi:10.1016/j.jcot.2024.102835

Femoral tunnel enlargement after medial patellofemoral ligament reconstruction is common and can be monitored using plain radiographs

J Clin Orthop Trauma. 2024 Nov 27:60:102835. doi: 10.1016/j.jcot.2024.102835. eCollection 2025 Jan.

Authors

Tobias Roberts¹, Laura Casey¹, Diego Abelleyra Lastoria¹, Samuel Walters¹, Toby Smith², Caroline Hing¹

Affiliations

¹ St. George's University Hospitals NHS Foundation Trust, London, SW17 0QT, UK.
² University of Warwick, Coventry, CV4 7AJ, UK.

PMID: 39720345
PMCID: PMC11665615 (available on 2025-11-27)
DOI: 10.1016/j.jcot.2024.102835

Abstract

Introduction: medial patellofemoral ligament reconstruction (MPFLr) is a common surgical procedure for treating patellar instability. Grafts can be fixed to the femur using a bone-tunnel technique with an interference screw. However, this may lead to femoral tunnel enlargement (FTE) post-operatively. The aim of this study was to assess the correlation between time after MPFLr and FTE, to evaluate factors that might influence FTE and to determine if FTE can be reliably evaluated with plain radiographs.

Methods: we conducted a single-surgeon series, retrospective review of 70 MPFLr (52 female; 18 male) between 2014 and 2022. We assessed change in femoral tunnel area compared with original tunnel area (TP0), on lateral radiographs at two time points. Time point one (TP1): mean 34 days (standard deviation (SD): 25); and Time Point 2 (TP2): mean 490 days (SD: 333). We analysed the relationship between surgical characteristics to FTE, and assessed inter- and intra-rater reliability of FTE.

Results: tunnel area significantly increased from TP0 to TP1 and TP2 (p < 0.001). Mean percentage increase in cross-sectional tunnel area (CTA) between TP0 and TP1 was 113 % (SD: 49 %). Mean percentage increase in CTA between TP0 and TP2 was 139 % (SD: 64 %). There were 25 cases (36 %) of tunnel malposition. There was no significant correlation between distance from the isometric point and FTE at TP1 (r = 0.05; 95 % confidence intervals (CI): -0.19 to 0.29) or TP2 (r = 0.17: 95 % CI: -0.068 to 0.39). There were no other significant correlations with FTE. Inter-rater reliability for FTE at TP1 was moderate (Inter-Class Coefficient (ICC): 0.67; 95 % CI: 0.47 to 0.80; p < 0.001), with intra-rater reliability being excellent (ICC: 0.94; 95 % CI: 0.90 to 0.96; p < 0.001).

Conclusion: FTE after MPFLr is common. Plain radiographs can be used reliably to monitor tunnel enlargement in clinical practice.

Keywords: Femoral tunnel enlargement; MPFL; Medial patellofemoral ligament reconstruction; Patellofemoral instability.