scholarly journals The Role of Abnormal Tibiofemoral Rotation in Pediatric and Adolescent Patellar Instability

2018 ◽  
Vol 6 (7_suppl4) ◽  
pp. 2325967118S0007
Author(s):  
David Bernholt ◽  
Joseph D. Lamplot ◽  
Eric Eutsler ◽  
Jeffrey J. Nepple
Keyword(s):  
Patellar Instability ◽  
External Rotation ◽  
Interobserver Reliability ◽  
Cruciate Ligament ◽  
Tibial Tubercle ◽  
Case Group ◽  
Trochlear Groove ◽  
Retrospective Case ◽  
Femoral Trochlea ◽  
Tibiofemoral Rotation

Objectives: Abnormal patellofemoral tracking has been implicated in patellar instability and can be influenced by the bony anatomy and alignment of the femoral trochlea, patella, and tibial tubercle. Tibiofemoral joint rotation has been recently suggested to play a role in patellofemoral kinematics but there has been little investigation of its contribution to patellar instability, including in pediatric and adolescent patients. Methods: A retrospective case-control design was utilized. 30 patients aged 9-18 with a prior patellar dislocation and an MRI of the involved knee were included. Cases were matched for age and gender with controls without patellar instability. Patients with ACL tears, tibial eminence or tubercle fractures, or prior surgery in the involved extremity were excluded. There was no difference in gender, age, height, but BMI was higher in the case group. MRI images taken with knee in extension were analyzed. Tibial tubercle-trochlear groove (TT-TG), tibial tubercle-posterior cruciate ligament (TT-PCL), and tibiofemoral rotation were measured. All measurements were performed by a single reader with excellent intra and interobserver reliability for tibiofemoral rotation (ICC-intra > .954 and ICC-inter > .905) demonstrated in a subset of patients. Results: The TT-TG was increased in patients with patellar instability at 16.3 mm compared to 10.9 mm in controls (p <.001) as was also the TT-PCL at 19.4 mm cases versus 17.6 mm (p=0.02). Tibiofemoral rotation was increased in patients with patellar instability with a mean 6.9° of tibial external rotation compared to 0.8° of tibial internal rotation in controls (p < .001). Overall, 30/41 (75.6%) of patients with patellar instability had tibiofemoral rotation >5° external rotation versus only 3/41 controls (7.3%). There was a strong correlation between TT-TG and tibiofemoral rotation (PCC = 0.776) and a moderate correlation between TT-TG and TT-PCL (PCC = .661). There was only a weak correlation between tibiofemoral rotation and TT-PCL. Conclusion: Increased tibiofemoral rotation is present in patients with patellar instability and may play a role in the pathophysiology of patellar instability. Increased tibiofemoral rotation can lead to an increased TT-TG even when TT-PCL is normal.

scholarly journals INCREASED TIBIOFEMORAL ROTATION WITH INCREASING SEVERITY OF PATELLAR INSTABILITY

2020 ◽  
Vol 8 (4_suppl3) ◽  
pp. 2325967120S0023
Author(s):  
Kenneth M. Lin ◽  
Evan W. James ◽  
Lindsay Schlichte ◽  
Grace Wang ◽  
Daniel Green
Keyword(s):  
Patellar Instability ◽  
External Rotation ◽  
Intraclass Correlation ◽  
Mpfl Reconstruction ◽  
Tibial Tubercle ◽  
Tibial Rotation ◽  
Trochlear Groove ◽  
Clinical Effects ◽  
Tibiofemoral Rotation ◽  
The Relationship

Background: Tibiofemoral rotation (TFR), specifically external tibial rotation, has been recently identified as a potential contributing factor to patellar instability. However, no previous studies have explored the clinical effects of differing degrees of TFR in relation to patellar instability. Purpose and Hypothesis: The purpose of this study is to investigate the relationship between severity of instability with degree of TFR. Our hypothesis is that fixed or obligatory dislocators (FOD) are more likely to have increased external TFR (tibial external rotation compared to femur) than standard patellar instability (SPI) patients requiring medial patellofemoral ligament (MPFL) reconstruction, who will have similar or slightly increased external TFR compared to normal controls. Methods: A retrospective study was performed with patients from 3 cohorts from April 2009 to February 2019: FOD, SPI, and controls with normal magnetic resonance imaging (MRI) of the knee. All FOD patients from the study time frame were analyzed, while controls and SPI patients were randomly selected. Patients were included for age under 18 years and diagnosis corresponding to one of the three cohorts, and excluded for outside institution MRI, and previous MPFL reconstruction or tibial tubercle osteotomy. TFR was measured on preoperative axial MRI using the posterior femoral and tibial condylar lines (Figure 1). Tibial tubercle to trochlear groove distance (TT-TG) was measured. Intraclass correlation coefficient (ICC) was calculated among 3 measurers. Statistical analysis using ANOVA and t-test was performed with significance set at α=0.05. Results: A total of 57 patients were included, 19 in each cohort. Average age was 13.2 years (range 10-17 years), with 31 females (54%). ICC for TT-TG and TFR were 0.90 and 0.72, respectively. TT-TG differed between the controls and SPI patients (both P<0.001), and controls and FOD patients (P<0.001), but not between SPI and FOD patients (P=0.12). TFR differed among the three groups: 8.4° (SD 16.7°) external TFR in FOD, 1.6° (SD 5.4°) external TFR in SPI, and 2.5° (SD 5.8°) internal TFR in controls (P=0.0089). FOD patients had significantly greater external tibial rotation than the SPI group (P=0.047). Conclusions: The degree of TFR is correlated with severity of patellar instability, with greater external tibial rotation seen in FOD than SPI patients, while TT-TG was not different. Further information on the relationship of TFR and patellar instability will not only improve understanding of pathogenesis and prognosis, but may also direct surgical treatment strategies in refractory or severe cases. [Figure: see text][Figure: see text]

scholarly journals Increased Tibiofemoral Rotation with Increasing Severity of Patellar Instability in the Pediatric Population

2020 ◽  
Vol 8 (7_suppl6) ◽  
pp. 2325967120S0048
Author(s):  
Evan James ◽  
Alexandra Aitchison ◽  
Lindsay Schlichte ◽  
Grace Wang ◽  
Daniel Green ◽  
...  
Keyword(s):  
Patellar Instability ◽  
External Rotation ◽  
Intraclass Correlation ◽  
Mpfl Reconstruction ◽  
Tibial Tubercle ◽  
Tibial Rotation ◽  
Trochlear Groove ◽  
Clinical Effects ◽  
Tibiofemoral Rotation ◽  
The Relationship

Objectives: Tibiofemoral rotation (TFR), specifically external tibial rotation, has been recently identified as a potential contributing factor to patellar instability. However, no previous studies have explored the clinical effects of differing degrees of TFR in relation to patellar instability. The purpose of this study is to investigate the relationship between severity of instability with degree of TFR. Our hypothesis is that fixed or obligatory dislocators (FOD) are more likely to have increased external TFR (tibial external rotation compared to femur) than standard patellar instability (SPI) patients requiring medial patellofemoral ligament (MPFL) reconstruction, who will have similar or slightly increased external TFR compared to normal controls. Methods: A retrospective study was performed with patients from 3 cohorts from April 2009 to February 2019: FOD, SPI, and controls with normal magnetic resonance imaging (MRI) of the knee. All FOD patients from the study time frame were analyzed, while controls and SPI patients were randomly selected. Patients were included for age under 18 years and diagnosis corresponding to one of the three cohorts, and excluded for outside institution MRI, and previous MPFL reconstruction or tibial tubercle osteotomy. TFR was measured on preoperative axial MRI using the posterior femoral and tibial condylar lines (Figure 1). Tibial tubercle to trochlear groove distance (TT-TG) was measured. Intraclass correlation coefficient (ICC) was calculated among 3 measurers. Statistical analysis using ANOVA and t-test was performed with significance set at α=0.05. Results: A total of 57 patients were included, 19 in each cohort. Average age was 13.2 years (range 10-17 years), with 31 females (54%). ICC for TT-TG and TFR were 0.90 and 0.72, respectively. TT-TG differed between the controls and SPI patients (both P<0.001), and controls and FOD patients (P<0.001), but not between SPI and FOD patients (P=0.12). TFR differed among the three groups: 8.4° (SD 16.7°) external TFR in FOD, 1.6° (SD 5.4°) external TFR in SPI, and 2.5° (SD 5.8°) internal TFR in controls (P=0.0089). FOD patients had significantly greater external tibial rotation than the SPI group (P=0.047). Conclusions: The degree of TFR is correlated with severity of patellar instability, with greater external tibial rotation seen in FOD than SPI patients, while TT-TG was not different. Further information on the relationship of TFR and patellar instability will not only improve understanding of pathogenesis and prognosis, but may also direct surgical treatment strategies in refractory or severe cases.

scholarly journals SPONTANEOUS CORRECTION OF EXTERNAL TIBIOFEMORAL ROTATION AND TIBIAL TUBEROSITY-TROCHLEAR GROOVE DISTANCE OCCURS AFTER MEDIAL PATELLOFEMORAL LIGAMENT RECONSTRUCTION IN FIXED OR OBLIGATORY DISLOCATORS

2021 ◽  
Vol 9 (7_suppl3) ◽  
pp. 2325967121S0013
Author(s):  
Alexandra H. Aitchison ◽  
Kenneth M. Lin ◽  
Daniel W. Green
Keyword(s):  
Patellar Instability ◽  
Ligament Reconstruction ◽  
Medial Patellofemoral Ligament ◽  
Extensor Mechanism ◽  
Tibial Tubercle ◽  
Trochlear Groove ◽  
Medial Patellofemoral Ligament Reconstruction ◽  
Force Vector ◽  
Tibiofemoral Rotation ◽  
The Mean

Background: Tibial tubercle to trochlear groove distance (TT-TG) and external tibiofemoral rotation (TFR) through the knee joint have been identified potential contributing factors to patellar instability. In patients with a fixed or obligatory lateral patella dislocation (FOD), the normal force vector of the extensor mechanism is altered, so instead of a direct axial pull to cause extension, it exerts a lateralizing and external rotatory force on the tibia via the tibial tubercle. Hypothesis/Purpose: The purpose of this study is to investigate postoperative changes in TT-TG and TFR after medial patellofemoral ligament reconstruction (MPFLR) in two clinical cohorts: standard traumatic patellar instability (SPI) patients and FOD patients. We hypothesized that by surgically relocating the patella in the trochlea, and re-establishing medial sided soft tissue tension, the increased medializing force vector on the patella may exert enough force to alter resting rotation of the tibia in relation to the femur in the FOD group. Methods: A retrospective study was performed from April 2009 to February 2019. FOD and SPI patients under 18 years with available magnetic resonance imaging (MRI) of the knee before and after MPFLR were eligible. All FOD patients in the time frame were analyzed and SPI patients were randomly selected. Exclusion criteria were outside institution MRI, concomitant alignment procedures done at the time of MPFLR, and prior MPFLR or tibial tubercle osteotomy. TT-TG and TFR (using the posterior femoral and tibial condylar lines) were measured blindly on initial axial MRI. Statistical analysis using a paired sample t-test was performed with significance set at p<0.05. Results: A total of 30 patients were included, 14 in the FOD group and 16 in the SPI group. The mean age at time of surgery was 13.9 years (range 10-17 years), 53% of the cohort was female, and the mean time from surgery to follow-up MRI was 2.0 years. Demographics by group are shown in Table 1. TT-TG and TFR were not significantly different preoperatively versus postoperatively in the SPI group (Table 2). In the FOD group, both TT-TG (17.7 vs 13.7, P=.019) and TFR (8.6 vs 3.1, P=.025) decreased significantly on postoperative MRI. Conclusion: The postoperative decrease in TT-TG and TFR in the FOD group suggests that MPFLR in fixed or obligatory dislocators can improve the external rotation deformity through the level of the joint, and thus may help normalize the forces acting through the extensor mechanism. Tables/ Figures [Table: see text][Table: see text]

scholarly journals Utility of Merchant View Radiographs for Assessment of TT-TG: A Comparison to MRI

2018 ◽  
Vol 6 (7_suppl4) ◽  
pp. 2325967118S0007 ◽  
Author(s):  
David Bernholt ◽  
Joseph D. Lamplot ◽  
Eric Eutsler ◽  
Jeffrey J. Nepple
Keyword(s):  
Patellar Instability ◽  
Interobserver Reliability ◽  
Pearson Correlation ◽  
Tibial Tubercle ◽  
Power Calculation ◽  
Trochlear Groove ◽  
Pearson Correlation Coefficient ◽  
Strongly Correlated ◽  
Radiographic Assessment ◽  
Bony Landmarks

Objectives: Lateralization of the tibial tubercle plays a significant role in the pathophysiology of patellar instability and is most often assessed by the tibial tubercle to trochlear groove distance (TT-TG) measured on CT or MRI with the knee in extension. However, tracking of the patella in 30 to 45 degrees of flexion has been suggested to be of greater clinical significance. Merchant radiographs can demonstrate the position of the tibial tubercle relative to the trochlear groove in this range of flexion and thus may serve as a valuable tool in the assessment of patellar tracking. The purpose of the current study was (1) to validate radiographic assessment of the merchant view TT-TG and (2) to determine the correlation with MRI-based measurements. Methods: To validate Merchant TT-TG as a marker of the position of the tibial tubercle, 41 patients between the ages of 10-18 had standardized Merchant radiographs in 45 degrees flexion yielding imaging of 82 knees. Lead markers were placed upon the skin centered over the tibial tubercle based on palpation. Radiographs were collected and analyzed. The TT-TG was measured as the distance between lines centered over the deepest point of the trochlear groove and the center of the tibial tubercle and perpendicular to the anterior condylar axis. In order to correlate Merchant TT-TG to MRI TT-TG, 16 additional patients were added to reach a total of 30 patients with a Merchant radiograph and MRI, as power calculation determined 29 knees needed to detect a Pearson correlation coefficient (PCC) of .500. There was excellent interobserver reliability between two readers for Merchant TT-TG with and without use of a radiographic marker (ICC = .975 and .923 respectively). Results: The tibial tubercle could be identified on Merchant radiograph in 67 images (81.7%). Merchant TT-TG measured with use of a marker was very strongly correlated measurement based on bony landmarks alone (PCC = .848). The Merchant TT-TG measured with bony landmarks alone was strongly correlated to MRI TT-TG (PCC = .602). The strength of this correlation was increased by standardizing TT-TG by patellar width (PCC = .710). MRI TT-TG was increased in patients with patellar instability at 13.9 mm compared to 10.5 mm (p <.01); Merchant TT-TG was also increased in patients with patellar instability at 9.1 mm compared to 1.9 mm (p < .001). Conclusion: Standardized Merchant radiographs without radiographic markers allow for assessment of TT-TG in the majority of patients. Merchant TT-TG strongly correlates with MRI TT-TG but measured 5-8 mm smaller than MRI TT-TG.

scholarly journals Arthroscopic assessment of patellofemoral tracking predicts patellar instability

2017 ◽  
Vol 5 (5_suppl5) ◽  
pp. 2325967117S0018
Author(s):  
Ritwik Kejriwal ◽  
Peter Annear
Keyword(s):  
Patellar Instability ◽  
Estimation Error ◽  
Interobserver Reliability ◽  
Patellofemoral Instability ◽  
Low Flow ◽  
Initial Assessment ◽  
Tibial Tubercle ◽  
P Value ◽  
Trochlear Groove ◽  
Intra Class Correlation

Objectives: Surgical management of patellar instability includes proximal realignment procedure such as MPFL reconstruction. The decision to add a distal realignment procedure of tibial tubercle transfer is based on severity of patellar instability judged on either TTTG distance or arthroscopic patellofemoral tracking. We set out to validate our use of arthroscopic patellofemoral tracking for patellar instability management algorithm by analyzing its reproducibility and whether it correlates with patellar instability. Methods: A prospective observational study was carried out at Perth Orthopaedic and Sports Medicine Centre. Patient clinical presentations were divided into three groups - patellofemoral instability, patellofemoral pain, and no patellofemoral symptoms. Standard technique included low flow arthroscopy with single anterolateral viewing portal. Height of the fluid bag and presence of a knee holder was recorded. Knee flexion angle where patella first centrally engages in the trochlear groove was defined as Patellofemoral Congruent Angle (PCA). PCA was estimated by the primary surgeon and the angle was confirmed using a sterile goniometer. A second surgeon, blinded to the initial assessment, then repeated the measurements. Surgeon estimation error, interobserver reliability, and correlation with clinical presentation was analysed. Results: 57 knees were assessed for interobserver reliability. Intra-class correlation was 0.994 between surgeon’s estimate and goniometer reading. Intra-class correlation was 0.992 between the two surgeon’s readings suggesting a very high correlation. 157 patients had their PCA recorded and compared with their diagnosis. Mean PCA was 40 degrees in normal patients, and 118 degrees in patellar instability (p-value <0.001). Conclusion: Arthroscopic assessment of patellofemoral tracking is reproducible and correlates with patellar instability. A cut-off value of 40 degrees is recommended to differentiate normal tracking from abnormal.

scholarly journals Radiologic Measurements in the Assessment of Patellar Instability: A Systematic Review and Meta-analysis

2021 ◽  
Vol 9 (5) ◽  
pp. 232596712199317
Author(s):  
Alex E. White ◽  
Peters T. Otlans ◽  
Dylan P. Horan ◽  
Daniel B. Calem ◽  
William D. Emper ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Systematic Review ◽  
Patellar Instability ◽  
Cruciate Ligament ◽  
Meta Analysis ◽  
Tibial Tubercle ◽  
Trochlear Groove ◽  
Resonance Imaging ◽  
Control Groups ◽  
And Control

Background: Numerous diagnostic imaging measurements related to patellar instability have been evaluated in the literature; however, little has been done to compare these findings across multiple studies. Purpose: To review the different imaging measurements used to evaluate patellar instability and to assess the prevalence of each measure and its utility in predicting instability. We focused on reliability across imaging modalities and between patients with and without patellar instability. Study Design: Systematic review; Level of evidence, 4. Methods: We performed a systematic review of the literature using the PubMed, SCOPUS, and Cochrane databases. Each database was searched for variations of the terms “patellar instability,” “patellar dislocation,” “trochlear dysplasia,” “radiographic measures,” “computed tomography,” and “magnetic resonance imaging.” Studies were included if they were published after May 1, 2009, and before May 1, 2019. A meta-analysis using a random effects model was performed on several measurements, comparing instability and control groups to generate pooled values. Results: A total of 813 articles were identified, and 96 articles comprising 7912 patients and 106 unique metrics were included in the analysis. The mean patient age was 23.1 years (95% CI, 21.1-24.5), and 41% were male. The tibial tubercle–trochlear groove (TT-TG) distance was the most frequently included metric (59 studies), followed by the Insall-Salvati ratio and Caton-Deschamps index (both 26 studies). The interobserver intraclass correlation coefficients were excellent or good for the TT-TG distance and Insall-Salvati ratio in 100% of studies reporting them; however, for the Caton-Deschamps index and Blackburne-Peel ratio, they were excellent or good in only 43% and 40% of studies. Pooled magnetic resonance imaging values for TT-TG distance ( P < .01), Insall-Salvati ratio ( P = .01), and femoral sulcus angle ( P = .02) were significantly different between the instability and control groups. Values for tibial tubercle–posterior cruciate ligament distance ( P = .36) and Caton-Deschamps index ( P = .09) were not significantly different between groups. Conclusion: The most commonly reported measurements for evaluating patellar instability assessed patellar tracking and trochlear morphology. The TT-TG distance was the most common measurement and was greater in the patellar instability group as compared with the control group. In addition, the TT-TG, tibial tubercle–posterior cruciate ligament, and patellar tendon–trochlear groove distances were highly reproducible measurements for patellar tracking, and the Insall-Salvati ratio had superior reproducibility for assessing patellar height.

scholarly journals Arthroscopic assessment of patellofemoral tracking predicts patellar instability

2017 ◽  
Vol 5 (5_suppl5) ◽  
pp. 2325967117S0019
Author(s):  
Ritwik Kejriwal ◽  
Peter Annear
Keyword(s):  
Patellar Instability ◽  
Estimation Error ◽  
Interobserver Reliability ◽  
Patellofemoral Instability ◽  
Low Flow ◽  
Initial Assessment ◽  
Tibial Tubercle ◽  
P Value ◽  
Trochlear Groove ◽  
Intra Class Correlation

Objectives: Surgical management of patellar instability includes proximal realignment procedure such as MPFL reconstruction. The decision to add a distal realignment procedure of tibial tubercle transfer is based on severity of patellar instability judged on either TTTG distance or arthroscopic patellofemoral tracking. We set out to validate our use of arthroscopic patellofemoral tracking for patellar instability management algorithm by analyzing its reproducibility and whether it correlates with patellar instability. Methods: A prospective observational study was carried out at Perth Orthopaedic and Sports Medicine Centre. Patient clinical presentations were divided into three groups - patellofemoral instability, patellofemoral pain, and no patellofemoral symptoms. Standard technique included low flow arthroscopy with single anterolateral viewing portal. Height of the fluid bag and presence of a knee holder was recorded. Knee flexion angle where patella first centrally engages in the trochlear groove was defined as Patellofemoral Congruent Angle (PCA). PCA was estimated by the primary surgeon and the angle was confirmed using a sterile goniometer. A second surgeon, blinded to the initial assessment, then repeated the measurements. Surgeon estimation error, interobserver reliability, and correlation with clinical presentation was analysed. Results: 57 knees were assessed for interobserver reliability. Intra-class correlation was 0.994 between surgeon’s estimate and goniometer reading. Intra-class correlation was 0.992 between the two surgeon’s readings suggesting a very high correlation. 157 patients had their PCA recorded and compared with their diagnosis. Mean PCA was 40 degrees in normal patients, and 118 degrees in patellar instability (p-value <0.001). Conclusion: Arthroscopic assessment of patellofemoral tracking is reproducible and correlates with patellar instability. A cut-off value of 40 degrees is recommended to differentiate normal tracking from abnormal.

scholarly journals Comparing the Tibial Tuberosity–Trochlear Groove Distance Between CT and MRI in Skeletally Immature Patients With and Without Patellar Instability

2021 ◽  
Vol 9 (1) ◽  
pp. 232596712097366
Author(s):  
Zhen-Zhen Dai ◽  
Lin Sha ◽  
Zi-Ming Zhang ◽  
Zhen-Peng Liang ◽  
Hao Li ◽  
...  
Keyword(s):  
Patellar Instability ◽  
Intraclass Correlation ◽  
Mean Difference ◽  
Tibial Tubercle ◽  
Control Group ◽  
Trochlear Groove ◽  
Skeletally Immature ◽  
Bony Landmarks ◽  
The Difference ◽  
Ct And Mri

Background: The tibial tubercle–trochlear groove (TT-TG) distance was originally described for computed tomography (CT), but it has been measured on magnetic resonance imaging (MRI) in patients with patellar instability (PI). Whether the TT-TG measured on CT versus MRI can be considered equivalent in skeletally immature children remains unclear. Purpose: To investigate in skeletally immature patients (1) the effects of CT versus MRI imaging modality and cartilage versus bony landmarks on consistency of TT-TG measurement, (2) the difference between CT and MRI measurements of the TT-TG, and (3) the difference in TT-TG between patients with and without PI. Study Design: Cross-sectional study; Level of evidence, 3. Methods: We retrospectively identified 24 skeletally immature patients with PI and 24 patients with other knee disorders or injury but without PI. The bony and cartilaginous TT-TG distances on CT and MRI were measured by 2 researchers, and related clinical data were collected. The interrater, interperiod (bony vs cartilaginous), and intermethod (CT vs MRI) reliabilities of TT-TG measurement were assessed with intraclass correlation coefficients. Results: The 48 study patients (19 boys, 29 girls) had a mean age of 11.3 years (range, 7-14 years). TT-TG measurements had excellent interrater reliability and good or excellent interperiod reliability but fair or poor intermethod reliability. TT-TG distance was greater on CT versus MRI (mean difference, 4.07 mm; 95% CI, 2.6-5.5 mm), and cartilaginous distance was greater than bony distance (mean difference, 2.3 mm; 95% CI, 0.79-3.8 mm). The TT-TG measured on CT was found to increase with the femoral width. Patients in the PI group had increased TT-TG distance compared with those in the control group, regardless of landmarks or modality used ( P > .05 for all). Conclusion: For skeletally immature patients, the TT-TG distance could be evaluated on MRI, regardless of whether cartilage or bony landmarks were used. Its value could not be interchanged with CT according to our results; however, further research on this topic is needed.

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