Radiographic Evaluation of Pediatric Patients with Patellofemoral Instability

Orellana, Kevin J.; Batley, Morgan G; Lawrence, J. Todd R.; Nguyen, Jie C.; Williams, Brendan A.

doi:10.1007/s12178-022-09780-5

Cited by 10 publications

(9 citation statements)

References 123 publications

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“…Similarly, our results suggest age‐dependent maturation with a normal adult value of 12.3 mm for TT‐TG distance. This is consistent with the pooled value of 12.85 mm on CT [32] and is 2–4 mm higher than the previously reported MRI measurement [7, 24, 27]. In a recent meta‐analysis, the TT‐TG distances measured on CT are substantially larger than those measured on MRI (9.83 mm) [32].…”

Section: Discussionsupporting

confidence: 91%

Impact of sex and age on the lateralisation of the tibial tubercle in normal paediatric and adolescent populations

Chen,

Sha,

Zhang

et al. 2024

Knee surg. sports traumatol. arthrosc.

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PurposeNumerous methods have been proposed to characterise tubercle lateralisation. However, their normal values and related changes remain unclear. Accordingly, it was aimed to determine the potential sex and age effects and determined the optimal individualised method of diagnosing lateralisation of the tibial tubercle in patients with recurrent patellar dislocation (RPD).MethodsMeasurements included the tibial tubercle–trochlear groove (TT‐TG) distance, tibial tubercle‐posterior cruciate ligament (TT‐PCL) distance and tibial tubercle lateralisation (TTL); and the proximal tibial width (PTW), trochlear width (TW) and trochlear dysplasia index (TDI), for adjustment. A two‐way analysis of variance was used to determine the effect of age, sex and their interaction within the normal group. When the age effect was statistically significant, a nonlinear regression was created. Areas under the receiver‐operating characteristic curve (AUCs) were calculated to assess diagnostic accuracy.ResultsA total of 277 normal participants (mean [SD] age, 13.5 [2.6] years; 125 [45.1%] female) and 227 patients with RPD (mean [SD] age, 13.5 [2.6] years; 161 [58.1%] female) were analysed. It was found that in the normal group, in patients aged 7–10, TT‐PCL distance (p = 0.006), TTL (p = 0.007) and TT‐PCL/PTW (p < 0.001) were significantly larger in females than in males. A significant sex effect was also detected on TT‐TG/TW (p = 0.014). TT‐TG distance, TT‐PCL distance, TTL and TT‐PCL/PTW (in male patients) approached an established normal adult value of 12.3 mm, 20.9 mm, 0.64 and 0.28, respectively, with increasing age (p < 0.001). The AUC was greater for TT‐TG/TDI and TT‐TG/TW (p ≤ 0.01) and TT‐TG/TDI outperformed TT‐TG/TW in patients aged 15–18 (p = 0.004).ConclusionsTubercle lateralisation increased with age and was affected by sex, with the exception of TT‐TG distance and TT‐TG/TDI. TT‐TG/TDI is the optimal method of diagnosing a lateralized tibial tubercle in patients with RPD. These findings assist with the evaluation of tubercle lateralisation in that they provide a proper protocol for paediatric and adolescent populations with RPD; and thus, will help determine whether medial tubercle transfer should be included among the tailored surgical procedures considered for the treatment of patients with RPD.Level of EvidenceLevel III.

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Section: Discussionsupporting

confidence: 91%

Impact of sex and age on the lateralisation of the tibial tubercle in normal paediatric and adolescent populations

Chen,

Sha,

Zhang

et al. 2024

Knee surg. sports traumatol. arthrosc.

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“…In addition to gait alteration and pain, genu valgum contributes to patellar instability due to an increased laterally directed force on the patella [7]. Additional anatomic factors that contribute to patellar instability include hyperlaxity, patella alta, increased tibial tubercle-trochlear groove (TT-TG) distance, patellar tilt, rotational deformity, and trochlear dysplasia [8][9][10][11][12][13]. Patellar instability may present with pain or may manifest as recurrent patella dislocations [14].…”

Section: Introductionmentioning

confidence: 99%

Mid-term outcomes of temporary medial distal femoral hemiepiphysiodesis with and without medial patellofemoral ligament repair for recurrent patellar instability in skeletally immature patients with genu valgum

Tomasevich,

Kantor,

Metz

et al. 2023

Journal of Pediatric Orthopaedics B

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Genu valgum contributes to patellar instability, though outcomes following temporary hemiepiphysiodesis via eight plating are less understood. The purpose of this study was to evaluate the outcomes and need for additional procedures following temporary hemiepiphysiodesis for the treatment of pediatric genu valgum and patellar instability, as well as evaluating the utility of a concurrent medial patellofemoral ligament (MPFL) repair. Patients who underwent medial distal femoral epiphysiodesis for the treatment of genu valgum and recurrent patellar instability were identified. Inclusion criteria were minimum 1-year follow-up and lack of concurrent ligamentous reconstruction. Patients were contacted to complete a questionnaire which included the International Knee Documentation Committee (IKDC) form and questions pertaining to knee function and patient satisfaction. Thirty-one patients aged 12.0 ± 1.9 years underwent 47 guided growth procedures and were included in final analysis. Seventeen knees (36%) required subsequent surgery for patellar instability. All patients requiring subsequent surgery were female, compared with 70% of patients not requiring subsequent surgery (P = 0.017). The MPFL repair group underwent fewer subsequent procedures to address instability, though this difference was NS (17 vs. 46%, P = 0.318). Mean IKDC score at 5.3 years follow-up among 18 survey respondents was 78.6. Medial distal femoral hemiepiphysiodesis may partially address recurrent patellar instability in skeletally immature patients with genu valgum. Concurrent MPFL repair may minimize the need for subsequent procedures to address recurrent instability. While correcting alignment may be helpful, patients should be aware of the potential need for further patellar instability surgery. Level of evidence: IV, case series.

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“…All evaluations were performed at the axial levels of the greatest patellar width and the trochlear groove, where the most proximal CT slice allowed visualisation of the intact classic Roman arch and posterior femoral condyles [5, 20, 21, 35]. The posterior condylar axis was the line connecting the most posteriorly projecting part of both the medial and lateral condyles.…”

Section: Methodsmentioning

confidence: 99%

Patellar shift ratio (PSR) is the optimal measurement for characterising lateral patellar shift and a reliable predictor of recurrent patellar dislocation

Chen

et al. 2022

Knee Surg Sports Traumatol Arthrosc

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PurposeTo propose a new measurement, the patellar shift ratio (PSR), for characterising lateral patellar shift; to determine its diagnostic accuracy in predicting recurrent patellar dislocation (RPD); and to identify the effect of patellar tilt and morphology on shift measurements. MethodsVariables including the PSR, bisect offset (BSO), BSO adjusted by trigonometric analysis, linear patellar displacement (LPD) distance and congruence angle were measured on axial computed tomography (CT). Furthermore, PSR was classified into grades determined by the threshold generated by receiver operating characteristic (ROC) curves. Youden’s index was used to identify the ideal threshold on the curve. The area under the ROC curve (AUC) values and likelihood ratios were calculated to assess diagnostic performance in predicting RPD. Correlation analysis was conducted to identify the effects of lateral tilt and the Wiberg index on lateral shift. Intra‐ and interobserver reliability were evaluated using the intraclass correlation coefficient. ResultsThe study included 54 RPD patients and 54 controls matched by sex and age. The threshold for PSR was 24.3% (sensitivity, 96.30%; specificity, 85.19%). AUCs were categorised as excellent for all protocols (P < 0.001). The positive likelihood ratio of the PSR for predicting RPD was 6.50. PSR was categorised in terms of lateral trochlear quadrants consisting of 25% increments. Lateral patellar tilt showed a strong positive correlation with BSO (P < 0.001); moderate correlations with PSR, LPD distance and adjusted BSO (P ≤ 0.001); and a weak correlation with congruence angle (P = 0.034). The Wiberg index presented a positive moderate correlation with BSO (P < 0.001), while no correlation was found with PSR, LPD distance, or congruence angle (n.s.). All parameters showed good repeatability (intraobserver) and reproducibility (interobserver). ConclusionsThe PSR showed excellent diagnostic performance as indicated by likelihood ratios, measurement accuracy (being relatively resistant to the effects of tilt and the Wiberg index), and intra‐ and interobserver reliability. The optimal PSR threshold for predicting RPD risk was 24.3%, and the grade of PSR (normal, 1–4) was also a reliable and easily calculated predictor of RPD. This quantifying method to characterise lateral patellar shift is an alternative useful method for clinical assessments of RPD patients and for research on patellofemoral congruence. Level of evidenceLevel III

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Radiographic Evaluation of Pediatric Patients with Patellofemoral Instability

Cited by 10 publications

References 123 publications

Impact of sex and age on the lateralisation of the tibial tubercle in normal paediatric and adolescent populations

Impact of sex and age on the lateralisation of the tibial tubercle in normal paediatric and adolescent populations

Mid-term outcomes of temporary medial distal femoral hemiepiphysiodesis with and without medial patellofemoral ligament repair for recurrent patellar instability in skeletally immature patients with genu valgum

Patellar shift ratio (PSR) is the optimal measurement for characterising lateral patellar shift and a reliable predictor of recurrent patellar dislocation

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