Radiographic images are inapplicable for a precise evaluation of the femoral tunnel position following MPFL reconstruction
- 19 Downloads
In medial patellofemoral ligament (MPFL) reconstruction, it remains controversial whether more accurate femoral tunnel positioning is correlated with improved clinical outcomes. The purpose was to verify the accuracy of methods for evaluating tunnel positioning, one of which is the use of postoperative radiographs, in determining the femoral tunnel position following MPFL reconstruction and to compare the variability of tunnel positions to the intraoperatively documented positions on a true-lateral view.
Seventy-three consecutive MPFL reconstructions were prospectively enrolled. Femoral tunnel positions were intraoperatively determined using fluoroscopy to obtain true-lateral radiographs. Postoperatively, lateral radiographic images were taken. Seven independent radiologists and seven independent orthopaedic knee surgeons evaluated the femoral tunnel position and amount of malrotation for each radiograph. Deviations from the Schoettle’s point were measured and repeated after 4 weeks. Intraobserver and interobserver analyses of variance were calculated to determine the reliability of measurements on both intraoperative and postoperative radiographs.
Fifty-six patients were included in the final analysis. Tunnel positions were unable to be identified on postoperative radiographs in 14% of cases on average, independent of the degree of radiograph rotation. Intraoperative images showed mean deviations from the tunnel position to the centre of Schoettle’s point of 1.9 ± 1.4 mm and 1.6 ± 1.0 mm in anterior–posterior and proximal–distal direction, respectively. Postoperative radiographs showed mean anterior–posterior and deviations of 7.4 ± 4.4 mm and 8.9 ± 5.8 mm assessed by orthopaedic surgeons and 10.6 ± 6.3 mm and 11.6 ± 7.1 mm assessed by radiologists at first and repeated measurement, respectively. The mean proximal–distal deviations were 4.8 ± 4.4 mm and 6.5 ± 6.0 mm and 7.2 ± 6.3 mm and 8.1 ± 7.1 mm, respectively. Measurement of tunnel position on intraoperative fluoroscopic images was significantly different compared to postoperative radiographs for each of the 14 observers (p < 0.05). Significant intraobserver and interobserver differences between the first and repeat measurements for both orthopaedic surgeons and radiologists were observed (p < 0.05).
Measurement of the femoral tunnel position on postoperative lateral radiographs is not an accurate or reliable method for evaluating tunnel position after MPFL reconstruction due to exposure, contrast, and malrotation of the radiograph from a true-lateral image. In contrast, intraoperative fluoroscopic control allows for a precise lateral view and correct tunnel positioning. Thus, postoperative radiographic images may be unnecessary for the evaluation of femoral tunnel positions, particularly when intraoperative fluoroscopy has been used.
Level II, prospective cohort study.
KeywordsMPFL reconstruction Femoral tunnel position Radiographic images Intraoperative fluoroscopy
VJ participated in the design of the study, collected data, performed the statistical analysis, and drafted the manuscript. VJ, LN, SS, and PK have methodically been involved in evaluating radiographic images. LN, SS, PK, AK, and TT have been involved in drafting the manuscript and revising it critically. SS performed all surgeries and intraoperative documentation of tunnel position. TT coordinated the study. AK performed final language editing. All authors have given final approval of the version to be published.
No external source of funding was used.
Compliance with ethical standards
Conflict of interest
All authors declare that there is no conflict of interests.
Ethical approval was obtained from the ethics committee of the University of Witten/Herdecke, Germany (IRB 146/2014). All procedures involving human participants were in accordance with the 1964 Helsinki declaration and its later amendments .
- 9.Gravesen KS, Kallemose T, Blond L, Troelsen A, Barfod KW (2018) High incidence of acute and recurrent patellar dislocations: a retrospective nationwide epidemiological study involving 24.154 primary dislocations. Knee Surg Sports Traumatol Arthrosc 26:1204–1209Google Scholar
- 15.McCarthy M, Ridley TJ, Bollier M, Wolf B, Albright J, Amendola A (2013) Femoral tunnel placement in medial patellofemoral ligament reconstruction. Iowa Orthop J 33:58–63Google Scholar
- 16.McNeilan RJ, Everhart JS, Mescher PK, Abouljoud M, Magnussen RA, Flanigan DC (2018) Graft choice in isolated medial patellofemoral ligament reconstruction: a systematic review with meta-analysis of rates of recurrent instability and patient-reported outcomes for autograft, allograft, and synthetic options. Arthroscopy 34(4):1340–1354CrossRefGoogle Scholar
- 20.Schneider DK, Grawe B, Magnussen RA, Ceasar A, Parikh SN, Wall EJ et al (2016) Outcomes after isolated medial patellofemoral ligament reconstruction for the treatment of recurrent lateral patellar dislocations: a systematic review and meta-analysis. Am J Sports Med 44:2993–3005CrossRefGoogle Scholar
- 28.Stupay KL, Swart E, Shubin Stein BE (2015) Widespread implementation of medial patellofemoral ligament reconstruction for recurrent patellar instability maintains functional outcomes at midterm to long-term follow-up while decreasing complication rates: a systematic review. Arthroscopy 31:1372–1380CrossRefGoogle Scholar