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Anatomic Factors Influencing a Persistent J-Sign After Medial Patellofemoral Ligament Reconstruction and Distal Tibial Tubercle Osteotomy in Patients With Recurrent Patellar Dislocations and Patella Alta: A Retrospective Cohort Study.

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Title: Anatomic Factors Influencing a Persistent J-Sign After Medial Patellofemoral Ligament Reconstruction and Distal Tibial Tubercle Osteotomy in Patients With Recurrent Patellar Dislocations and Patella Alta: A Retrospective Cohort Study.
Authors: Vial Irarrazaval, Raimundo, Turkula, Stefan, Tompkins, Marc, Agel, Julie, Arendt, Elizabeth
Source: American Journal of Sports Medicine; Jun2025, Vol. 53 Issue 7, p1554-1562, 9p
Subject Terms: TIBIA surgery, ARTICULAR ligaments, T-test (Statistics), DATA analysis, RECEIVER operating characteristic curves, LOGISTIC regression analysis, FISHER exact test, TIBIA, TREATMENT effectiveness, RETROSPECTIVE studies, MAGNETIC resonance imaging, DESCRIPTIVE statistics, CHI-squared test, OSTEOTOMY, KNEE joint, LONGITUDINAL method, ODDS ratio, MEDICAL records, ACQUISITION of data, STATISTICS, PATELLA dislocation, DISEASE relapse, PATELLA, PLASTIC surgery, DATA analysis software, CONFIDENCE intervals, PATELLAR tendon, RANGE of motion of joints
Abstract: Background: The J-sign is a marker of abnormal patellar tracking and is associated with bony abnormalities. When patella alta is present, distal tibial tubercle osteotomy (dTTO) can enable the patella to engage in a more distal/deeper groove, often eliminating the J-sign. Purpose: To determine which anatomic findings are associated with a persistent J-sign after medial patellofemoral ligament reconstruction (MPFL-R) and dTTO in patients with recurrent lateral patellar dislocations and patella alta. Study Design: Cohort study; Level of evidence, 4. Methods: A retrospective cohort study of 93 knees (77 patients) with recurrent lateral patellar dislocations and the J-sign, treated by a single surgeon with MPFL-R and dTTO without trochleoplasty, was conducted. Demographic, imaging, and surgical data were obtained from medical records. The following measurements were obtained: Caton-Deschamps index (CDI), patellotrochlear index, tibial tubercle–trochlear groove (TT-TG) distance, patellar tendon–lateral trochlear ridge (PT-LTR) distance, lateral patellar tilt, tibiofemoral joint rotation (TFJR), lateral trochlear inclination (LTI), trochlear depth, sulcus angle, and sagittal bump height. The postoperative J-sign was assessed. Patients were categorized into the resolved J-sign group or persistent J-sign group. Binary logistic regression was performed to identify significant predictors of a postoperative J-sign. Cutoff values were determined by receiver operating characteristic curve analysis using the Youden index. The Fisher exact test was used to compare frequencies. Results: The J-sign was not observed postoperatively in 56 cases (60.2%) and was thus considered resolved. Preoperative characteristics revealed differences between the resolved J-sign and persistent J-sign groups for mean lateral patellar tilt, PT-LTR distance, TFJR, sulcus angle, trochlear depth, TT-TG distance, sagittal bump height, and LTI. The mean amount of distalization, patellotrochlear index, and preoperative and postoperative CDI were similar between the groups. Logistic regression identified TFJR, PT-LTR distance, and LTI as significant predictors of a persistent J-sign. An increased risk of a persistent J-sign was found for a TFJR ≥6° (odds ratio [OR], 14.9 [95% CI, 5.4-41.6]), PT-LTR distance ≥13 mm (OR, 12.3 [95% CI, 4.3-35.5]), and LTI ≤10° (OR, 4.1 [95% CI, 1.6-10.4]). The frequency of a persistent J-sign was 3.8% for cases with no risk factors above the threshold value, 10.5% with 1 risk factor, 63.0% with 2 risk factors, and 87.5% with all 3 risk factors present. Conclusion: A persistent J-sign was associated with imaging measurements of a more lateralized extensor mechanism (greater PT-LTR distance), trochlear dysplasia (lower LTI), and increased external TFJR. [ABSTRACT FROM AUTHOR]
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Abstract:Background: The J-sign is a marker of abnormal patellar tracking and is associated with bony abnormalities. When patella alta is present, distal tibial tubercle osteotomy (dTTO) can enable the patella to engage in a more distal/deeper groove, often eliminating the J-sign. Purpose: To determine which anatomic findings are associated with a persistent J-sign after medial patellofemoral ligament reconstruction (MPFL-R) and dTTO in patients with recurrent lateral patellar dislocations and patella alta. Study Design: Cohort study; Level of evidence, 4. Methods: A retrospective cohort study of 93 knees (77 patients) with recurrent lateral patellar dislocations and the J-sign, treated by a single surgeon with MPFL-R and dTTO without trochleoplasty, was conducted. Demographic, imaging, and surgical data were obtained from medical records. The following measurements were obtained: Caton-Deschamps index (CDI), patellotrochlear index, tibial tubercle–trochlear groove (TT-TG) distance, patellar tendon–lateral trochlear ridge (PT-LTR) distance, lateral patellar tilt, tibiofemoral joint rotation (TFJR), lateral trochlear inclination (LTI), trochlear depth, sulcus angle, and sagittal bump height. The postoperative J-sign was assessed. Patients were categorized into the resolved J-sign group or persistent J-sign group. Binary logistic regression was performed to identify significant predictors of a postoperative J-sign. Cutoff values were determined by receiver operating characteristic curve analysis using the Youden index. The Fisher exact test was used to compare frequencies. Results: The J-sign was not observed postoperatively in 56 cases (60.2%) and was thus considered resolved. Preoperative characteristics revealed differences between the resolved J-sign and persistent J-sign groups for mean lateral patellar tilt, PT-LTR distance, TFJR, sulcus angle, trochlear depth, TT-TG distance, sagittal bump height, and LTI. The mean amount of distalization, patellotrochlear index, and preoperative and postoperative CDI were similar between the groups. Logistic regression identified TFJR, PT-LTR distance, and LTI as significant predictors of a persistent J-sign. An increased risk of a persistent J-sign was found for a TFJR ≥6° (odds ratio [OR], 14.9 [95% CI, 5.4-41.6]), PT-LTR distance ≥13 mm (OR, 12.3 [95% CI, 4.3-35.5]), and LTI ≤10° (OR, 4.1 [95% CI, 1.6-10.4]). The frequency of a persistent J-sign was 3.8% for cases with no risk factors above the threshold value, 10.5% with 1 risk factor, 63.0% with 2 risk factors, and 87.5% with all 3 risk factors present. Conclusion: A persistent J-sign was associated with imaging measurements of a more lateralized extensor mechanism (greater PT-LTR distance), trochlear dysplasia (lower LTI), and increased external TFJR. [ABSTRACT FROM AUTHOR]
ISSN:03635465
DOI:10.1177/03635465251336162