Association between tibiofemoral rotation and patellofemoral alignment before and after surgical realignment for lateral patellar instability
4 affiliations
- 1Department of Orthopaedic and Trauma Surgery, University Medical Centre Mannheim, Medical Faculty Mannheim University of Heidelberg Mannheim Germany
- 2Arcus Kliniken Pforzheim Pforzheim Germany
- 3Department of Trauma, Hand and Reconstructive Surgery, Departments and Institutes of Surgery Saarland University Homburg Germany
- 4Department for Orthopaedics and Trauma Surgery, BG Klinik Ludwigshafen University of Heidelberg Ludwigshafen Germany
Abstract
Purpose: To evaluate the relationship between tibiofemoral rotation (TFR) and patellofemoral alignment parameters before and after surgical stabilisation for patellar instability and to determine whether correction of extensor mechanism (apparatus) alignment is associated with a reduction in TFR.
Methods: A total of 141 patients (99 females; mean age 24.5 ± 8.2 years) treated for recurrent patellar instability were included. Medial patellofemoral ligament reconstruction and thin‐flap trochleoplasty were performed, with tibial tubercle osteotomy (TTO) added when indicated. Pre and postoperative parameters, including trochlear bump, patellar tendon–trochlear groove angle (PT‐TGA), sagittal tibial tubercle–trochlear groove distance (sTTTG), tibial tubercle–trochlear groove distance (TT‐TG), lateral trochlear inclination (LTI), bisect offset and Caton‐Deschamps index (CDI), were assessed alongside TFR. Associations were analysed using Pearson/Spearman coefficients and multivariable linear regression models. Intra and interobserver reliability were assessed using intraclass correlation coefficients (ICC).
Results: Significant postoperative improvements were observed across all alignment parameters (p < 0.001). The largest reductions were recorded for trochlear bump (−3.74 mm), PT‐TGA (−10.02°) and sTTTG (−4.57 mm). TFR also decreased significantly (−1.55°, 95% CI: 0.86–2.23°, p < 0.001). Preoperatively, TFR was most strongly correlated with PT‐TGA (r = 0.52) and bisect offset (r = 0.445), while no associations with trochlear bump or CDI were found. Postoperatively, TFR remained associated with PT‐TGA (r = 0.305), sTTTG (r = 0.258) and bisect offset (r = 0.237). Changes in TFR (Δ TFR) were primarily correlated with PT‐TGA (Δ PT‐TGA) and bisect offset (Δ bisect offset). In multivariable models, PT‐TGA was identified as the sole independent predictor of preoperative TFR (β = 0.33) and Δ TFR (β = 0.376). Postoperatively, TFR was independently predicted by PT‐TGA (β = 0.289), sTTTG (β = 0.247) and CDI (β = −0.225). Intraobserver reliability was excellent (ICC: 0.947–0.992) and interobserver reliability was good to excellent (ICC: 0.877–0.956).
Conclusion: TFR was significantly associated with axial patellofemoral alignment, most consistently with PT‐TGA and decreased significantly following surgical realignment of the extensor mechanism, although rotation was not addressed directly. The parallel changes in TFR and PT‐TGA indicate that rotational alignment is related to extensor mechanism alignment and should be interpreted in conjunction with it rather than as an isolated, fixed parameter.
Level of Evidence: Level IV.
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BibTeX
@article{schmidt2026association,
title = {{Association between tibiofemoral rotation and patellofemoral alignment before and after surgical realignment for lateral patellar instability}},
author = {Sebastian Schmidt and Abd El Nasser Oudeh and Emmanouil Liodakis and Felix Zimmermann and Peter Balcarek},
journal = {Journal of Experimental Orthopaedics},
year = {2026},
month = nov,
doi = {10.1002/jeo2.70979},
url = {https://doi.org/10.1002/jeo2.70979},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Association between tibiofemoral rotation and patellofemoral alignment before and after surgical realignment for lateral patellar instability
AU - Sebastian Schmidt
AU - Abd El Nasser Oudeh
AU - Emmanouil Liodakis
AU - Felix Zimmermann
AU - Peter Balcarek
PY - 2026
DA - 2026/11/05
JO - Journal of Experimental Orthopaedics
DO - 10.1002/jeo2.70979
UR - https://doi.org/10.1002/jeo2.70979
AB - Purpose: To evaluate the relationship between tibiofemoral rotation (TFR) and patellofemoral alignment parameters before and after surgical stabilisation for patellar instability and to determine whether correction of extensor mechanism (apparatus) alignment is associated with a reduction in TFR. Methods: A total of 141 patients (99 females; mean age 24.5 ± 8.2 years) treated for recurrent patellar instability were included. Medial patellofemoral ligament reconstruction and thin‐flap trochleoplasty were performed, with tibial tubercle osteotomy (TTO) added when indicated. Pre and postoperative parameters, including trochlear bump, patellar tendon–trochlear groove angle (PT‐TGA), sagittal tibial tubercle–trochlear groove distance (sTTTG), tibial tubercle–trochlear groove distance (TT‐TG), lateral trochlear inclination (LTI), bisect offset and Caton‐Deschamps index (CDI), were assessed alongside TFR. Associations were analysed using Pearson/Spearman coefficients and multivariable linear regression models. Intra and interobserver reliability were assessed using intraclass correlation coefficients (ICC). Results: Significant postoperative improvements were observed across all alignment parameters (p < 0.001). The largest reductions were recorded for trochlear bump (−3.74 mm), PT‐TGA (−10.02°) and sTTTG (−4.57 mm). TFR also decreased significantly (−1.55°, 95% CI: 0.86–2.23°, p < 0.001). Preoperatively, TFR was most strongly correlated with PT‐TGA (r = 0.52) and bisect offset (r = 0.445), while no associations with trochlear bump or CDI were found. Postoperatively, TFR remained associated with PT‐TGA (r = 0.305), sTTTG (r = 0.258) and bisect offset (r = 0.237). Changes in TFR (Δ TFR) were primarily correlated with PT‐TGA (Δ PT‐TGA) and bisect offset (Δ bisect offset). In multivariable models, PT‐TGA was identified as the sole independent predictor of preoperative TFR (β = 0.33) and Δ TFR (β = 0.376). Postoperatively, TFR was independently predicted by PT‐TGA (β = 0.289), sTTTG (β = 0.247) and CDI (β = −0.225). Intraobserver reliability was excellent (ICC: 0.947–0.992) and interobserver reliability was good to excellent (ICC: 0.877–0.956). Conclusion: TFR was significantly associated with axial patellofemoral alignment, most consistently with PT‐TGA and decreased significantly following surgical realignment of the extensor mechanism, although rotation was not addressed directly. The parallel changes in TFR and PT‐TGA indicate that rotational alignment is related to extensor mechanism alignment and should be interpreted in conjunction with it rather than as an isolated, fixed parameter. Level of Evidence: Level IV.
SN - 2197-1153
ER -