Trochlear Groove Angle Research Articles

Medial orientation of the trochlear groove is a strong indicator of high-grade trochlear dysplasia.

The objective is to evaluate the orientation of the trochlear groove in patients with objective patellar instability (OPI) compared to a control group. The hypothesis is that the trochlear groove angle (TGA) is correlated with the severity of the trochlear dysplasia. From 2019 to 2023, magnetic resonance imaging of 82 knees with OPI were compared with 82 control knees. TGA quantified the angle between the femoral anatomical axis and the trochlear groove. The intraclass correlation coefficient for TGA was evaluated. Central spur in the sagittal plane (CSSP) and cranial trochlear orientation (CTO) angle were also measured. TGA, CSSP and CTO were compared between the two groups. A TGA subgroup analysis separating the OPI group into low-grade (CSSP < 5 mm or negative CTO) and high-grade dysplasia (CSSP ≥ 5 mm or positive CTO) was also performed. A significant difference (p < 0.001) was found between the TGA of the OPI group (mean [SD], 11.3 [3.7]°) and the control group (4.2 [2.5]°). TGA for patients with high-grade dysplasia (11.9 [3.8]°) was significantly higher than patients with low-grade dysplasia (9.6 [3.9]°). Patients with OPI have a TGA of 11°, compared to the control group, which exhibits a TGA of 4°. The femoral mechanical axis can be considered an appropriate threshold for separating these two groups. Furthermore, TGA is correlated with the severity of dysplasia. Case-control study. Level III.

The Morphologic Patella Entry Point Into the Proximal Trochlea Is More Lateral in Recurrent Dislocators Than Controls as Measured by Entry Point–Trochlear Groove Angle

PurposeThe purpose of this work is to create a metric for evaluating the degree of laterality of the patella’s entry into the trochlea, the entry point-trochlear groove (EP-TG) angle, and to evaluate if this laterality is associated with recurrent patella instability. MethodsThe time frame of the study was January 2020 to February 2023. The inclusion criteria were patients treated by the senior author (JPF) (with the exception of two patients who were treated by another provider at the institution who was aware of the study) who have been diagnosed with recurrent atraumatic patellar dislocations. Controls without knee pathology were selected from the New Mexico Decedent Imaging Database (NMDID). Simpleware ScanIP was used to create three-dimensional (3D) models of the distal femurs from CT scans. AP images of these 3D models were uploaded to a custom EP-TG angle measuring tool. Three measurers used the tool to measure the EP-TG angle of the distal femurs. Results28 patients were included for the recurrent dislocator group. 24 decedents from NMDID were selected for the control group, each with a left or right knee chosen randomly for measurement. A one-sided Mann-Whitney U test, used to evaluate whether the recurrent dislocators had higher EP-TG angle values, yielded a p value <0.001, demonstrating a high level of significance. A Bayesian mixed effect model, used to determine how different the EP-TG angles are between the two groups, gave a posterior predictive interval (PPI) of [11.93, 19.12] degrees for the EP-TG angle shift of dislocators. The intraclass correlation coefficient was 0.648. ConclusionsThe morphological entry point of the patella into the proximal trochlea is more lateral in recurrent patella dislocators than in controls. This increased laterality can be measured by EP-TG angle, which may be useful information for optimizing treatment of recurrent patella instability. Level of EvidenceLevel III Case Control Study

Morphometric Findings in Medial Patellofemoral Ligament Rupture Compared to Individually-Matched Controls

BACKGROUND&#x0D; The purpose of the present study was to evaluate patellar height and trochlear groove angle in individuals with and without medial patellofemoral ligament rupture for surgical reconstruction and possible clinical use.&#x0D; METHODS&#x0D; The study had a retrospective design, and included 149 people (53 females, 96 men) who were between the ages of 18 and 36 admitted to the Orthopedic Clinic of Bartın State Hospital with various complaints in knee joints and different preliminary diagnoses between January 2005 and December 2020. The study population was examined as two groups, those with and without medial patellofemoral rupture. The study included 61 patients with medial patellofemoral ligament rupture and 88 patients without medial patellofemoral ligament rupture. Patellar morphology, patellar height, trochlear morphology, and patellar alignment were measured from digital MRI images.&#x0D; RESULTS&#x0D; As a result of the study, while significant differences were detected in trochlear groove angle, there wasn’t significant differences in patella elevation (patellar height) between the groups (with and without medial patellofemoral ligament rupture).&#x0D; CONCLUSIONS&#x0D; Our study has versatile evaluation parameters, it will make a significant contribution to the literature.

Patellar Tilt and Patellar Tendon–Trochlear Groove Angle Present the Optimum Magnetic Resonance Imaging Diagnostic Reliability for Patients With Patellar Instability

To describe, in controls and in a population with patellar instability, magnetic resonance imaging values of measurements representing major associated factors for patellar instability (patellar height, trochlear dysplasia, and extensor mechanism alignment), as well as their cutoff values. In total, 323 knee magnetic resonance imaging scans, 142 with patellar instability and 181 controls without patellofemoral complaints (anterior cruciate, medial collateral ligament, meniscus ruptures or normal) were evaluated. Means, normality values in the control population, ideal cutoff values through receiver operating characteristic curves analysis, and interobserver reliability (intraclass correlation coefficient) were described for a series of measurements. All measurements were statistically different in control and instability patients, except for the patellotrochlear index and tibial tuberosity to posterior cruciate ligament distance. The interobserver intraclass correlation coefficient was good or excellent (above 0.75) only for the patellotrochlear index, patellar tendon-trochlear groove (PTTG) angle, and patellar tilt. The optimal cutoff value for each measurement was: PTTG angle ≥25.3o with sensitivity (S) of 70% and specificity (E) of 89%, patellar tilt ≥16o (S: 69% and E: 84%), trochlear sulcus angle ≥153o (S: 75% and E: 76%), Carrillon ≤12.8o (S: 62% and E: 87%), PTTG distance ≥11mm (S: 71% and E:78%), Caton-Deschamps index ≥1.23 (S: 72% and E: 76%) and trochlear bump ≥3.95 mm (S: 76% and E: 65%). Caton-Deschamps index (≥1.23), trochlear sulcus angle (≥153o), ventral prominence of the trochlea (≥3.95 mm), PTTG distance (≥11 mm), PTTG angle (≥25.3o), Carrillon angle (≤12.8o), and patellar tilt (≥16o) presented better diagnostic performance for patellar instability. Patellotrochlear index and tibial tuberosity to posterior cruciate ligament distance were not related to patellar instability. The interobserver reliability of the factors related to patellar instability was excellent only for the PTTG angle and lateral patellar tilt. III, retrospective case-control study.

Patellar Tendon–Trochlear Groove Angle Measured on a Single Computed Tomography Slice of the Distal Femoral Trochlear Groove Is a Reliable Measurement for the Evaluation of Patellar Instability

To verify the reliability of patellar tendon-trochlear groove angle (PTTG-A) measured by computed tomography (CT) and the clinical significance in evaluation of patellar instability. A retrospective study of hospitalized patients with knee pain or injury and had knee CT from January 2017 to June 2021 was performed. PTTG-A and tibial tuberosity-trochlear groove (TT-TG) distance were measured on CT. Spearman correlation analysis was analyzed between the 2 measurements. The intraclass correlation coefficient was determined for inter- and intraobserver reproducibility. The capacity of PTTG-A and TT-TG to predict patellar instability was evaluated by the receiver operating characteristic curve. Data from the control group were used to determine the pathologic thresholds and logistic regression analysis. Included were 113 patients. There were 60 patients with the history of at least 2 episodes of patellar dislocation (study group) and 53 patients without a history of patellar dislocation (control group). The respective PTTG-A and TT-TG distances in the study group (35.2 ± 8.4° and 19.6 ± 4.6 mm) were significantly greater than those of the controls (20.8 ± 5.8° and 13.3 ± 4.5 mm) (P < .001). The correlation between the 2 measurements was strong (r= 0.730, P < .001). The inter- and intraobserver reliability of the PTTG-A were better than TT-TG distance in both groups. The AUC of PTTG-A was greater than that of the TT-TG distance (0.895 vs 0.769, respectively). With the cutoff value of PTTG-A and TT-TG being 26.3° and 16.3 mm, the value of the pathologic threshold of PTTG-A was 30.0°, with a dominance ratio of 16.88 (95% confidence interval 2.88-98.89, P= .002). The PTTG-A measured on a single CT slice of the distal femoral trochlear groove is a more reliable measurement than TT-TG distance for the prediction of patellar instability. III; A retrospective cohort study.

Computed tomographic measurements of the femoral trochlea in dogs with and without medial patellar luxation.

To determine cutoff values in small (SB) and medium/large (MLB) breed dogs with and without medial patellar luxation (MPL) for identifying abnormal femoral trochlea morphology. Original research. A total of 80 computed tomographic (CT) scans from client-owned dogs METHODS: Four groups of 20 dogs were created: (1) control SB, (2) control MLB, (3) MPL-SB, and (4) MPL-MLB. Two authors measured the femoral trochlear groove angle (FTGA), femoral trochlear angle (FTA), and femoral trochlear ridge inclination angle (FTRIA) in two points with CT. ANOVA and ROC-analysis were tested to the control and MPL groups to assess sensitivity, specificity, and cutoff values. Statistical significance was set to p < .05. Intraclass correlation coefficients evaluated the inter-rater agreement. FTGA (± SD) in control SB (128.8° ± 4.7°) and control MLB (119.2° ± 5.6°), was smaller (p < .0001) than in MPL-SB (139.4° ± 4.4°) and MPL-MLB (133.7° ± 5.1°). FTA and FTRIA were decreased (p=.12, p=.23) in MPL-SB (2.1° ± 6.8; -0.3° ± 3.3°) and MPL-MLB (3.8° ± 5.6°; 1.7° ± 4.5°) compared to control SB (0.2° ±4.1; -0.1° ± 2.6°) and control MLB (5.3° ± 2.8°; 3.1° ± 1.3°). Cutoff values for FTGA, FTA, and FTRIA were > 134°, < -5.9°, < -2 ° (SB), and > 128.3°, < -0.4°, < -0.4° (MLB). Sensitivity, specificity, and inter-rater agreement were superior for FTGA than FTA and FTRIA. Dogs without MPL had a deeper femoral trochlear groove than MPL dogs. SB had a shallower groove than MLB. The measurement of FTA and FTRIA was not reliable. A FTGA <134° (SB) and < 128° (MLB) may be considered as a cutoff for trochleoplasty decision-making.

Modified particle swarm optimization based magnetic resonance imaging analysis for identification of risk factors tissue damage incidence

AbstractThis study was to analyse the risk factors of unstable patella and the incidence of tissue damage (TD) with magnetic resonance imaging (MRI) image under the modified particle swarm optimization (MPSO). In this study, 45 patients with patella instability who visited hospital from 1 November 2018 to 28 September 2020 were selected as the experimental group (group E), and 45 volunteers with healthy knee joints were recruited as the control group (group C). MRI images under MPSO were to evaluate the four groups of related indicators (trochlear groove angle, trochlear groove depth, trochlear surface ratios, and Insall‐Salvati index) of unstable patella in the two groups and count the incidence of TD caused by unstable patella. Comparison of four indicators revealed that there was an obvious difference in the data of the two groups. The abnormal rate of patients with unstable patella in the group E was much higher than that of the group C, and the difference was statistical (p &lt; 0.05). The incidences of trochlea dysplasia and high patella accounted for 88.9% and 57.8% in group E and accounted for 4.4% and 3.2% in the group C, respectively, showing statistically obvious differences (p &lt; 0.05). The incidence of patella cartilage TD, thigh cartilage TD, lateral meniscus TD, medial meniscus TD, patella medial retinaculum TD, patella lateral retinaculum TD, patellar ligament damage, and joint effusions were 14.5%, 11.45%, 50.38%, 49.62%, 10.69%, 16.03%, 9.16%, and 79.39%, respectively in the patients with unstable patella in the group E. In short, trochlear dysplasia and high patella were risk factors for unstable patella, and unstable patella was one of the risk factors for multiple TDs of the knee joint. This study provided a new research basis for the early treatment of unstable patella.

Magnetic Resonance Imaging Evaluation of Patellofemoral Joint.

Patellofemoral pain is the leading cause of knee pain in young adults. Magnetic resonance imaging plays an important role in early diagnosis of patellofemoral joint pathology. This study was carried out to evaluate the patellofemoral joint using magnetic imaging resonance and describe various predisposing factors for patellofemoral instability. The study was carried in Department of Radiology, BPKIHS over a period of six months from February 2020 to August 2020. All patients with clinical diagnosis of patellar instability were included and Magnetic resonance imaging was done using standard knee protocol and findings were noted on structured proforma. Analysis was done using statistical package for the social sciences version 20 applying simple descriptive statistical methods. A total of 60 patients who underwent MRI knee were analyzed, out of which 28(46.7%) patients were male while 32(53.3%) patients were female. 44 patients (58.3%) had various predisposing factors for patellar instability. The commonest predisposing factor was patellar subluxation (73.3%) followed by abnormal trochlear groove angle (58.3%) and patellar translation (increased tibia tubercle trochlear groove distance) (53.3%). Various MRI findings in our study were bone contusion (28 cases,46.7%), joint effusion (36 cases,60%), medial patellofemoral ligament injury (11cases ,18.3%), erosion of patellar cartilage (5 cases,8.3%), femoral cartilage erosion (3 cases,5%),loose bodies (2 cases,3.3%), subchondral edema (3 cases,5%) and meniscus injury (18 cases,30%). Magnetic resonance imaging is not only useful in assessing lesions of the bone, cartilage and ligaments of patellofemoral joint but also enables detection of various predisposing factors for patellofemoral instability.

Anatomical Risk Factors for Anterior Cruciate Ligament Injury Are Not Important As Patellar Instability Risk Factors in Patients with Acute Knee Injury.

To compare in magnetic resonance imaging the anatomical risk factors for anterior cruciate ligament (ACL) injury and patellar dislocation among patients who suffered acute knee injury, 105 patients with acute knee injury resulting in 38 patellar dislocations (patella group), 35 ACL injuries (ACL group), and 32 meniscus or medial collateral ligament injuries (control group) were included. These groups were compared for risk factors for patellar dislocation (patellar height, trochlear dysplasia, and quadriceps angle of action) and for ACL injury (intercondylar width, posterior inclination of tibial plateaus, and depth of the medial plateau). Univariate analysis found statistically significant differences (p < 0.05) between the patella and ACL groups in patellar height (Caton-Deschamps [CD] 1.23 vs. 1.07), trochlear facet asymmetry (55 vs. 68%), PTTG (13.08 vs. 8.01 mm), and the patellar tip and trochlear groove (PTTG) angle (29.5 vs. 13.71 degrees). The patella group also differed from control in medial plateau inclination (4.8 vs. 1.87 degrees), patellar height (CD 1.23 vs 1.08), trochlear facet asymmetry (55 vs. 69%), lateral trochlear inclination (17.11 vs. 20.65 degrees), trochlear depth (4.1 vs. 6.05 mm), PTTG (13.08 vs. 9.85 mm), and the PTTG angle (29.5 vs. 17.88 degrees). The ACL and control groups were similar in all measures. Multivariate analysis found the following significant determinants between the Patella and Control groups: patellar height (CD index, odds ratio [OR]: 80.13, p = 0.015), trochlear anatomy (asymmetry of facets M/L, OR: 1.06, p = 0.031) and quadriceps action angle (PTTG angle, OR: 1.09, p = 0.016); between the ACL and control groups: PTTG angle (OR: 0.936, p = 0.04) and female gender (OR: 3.876, p = 0.032); and between the patella and ACL groups, the CD index (OR: 67.62, p = 0.026), asymmetry of the M/L facets (OR: 1.07, p = 0.011) and PTTG angle (OR: 1.16, p < 0.001). In conclusion, in patients with acute knee injury, the anatomical factors patellar height, trochlear dysplasia, and quadriceps angle of action were related to the occurrence of patellar dislocation. None of the anatomical factors studied was related to the occurrence of anterior cruciate ligament injury.

Preoperative planning of tibial tubercle medialisation according to the trochlear groove angle

The tibial tubercle-trochlear groove distance (TT-TG) was first described four decades ago. Since then, a considerable body of research has become available on the pathophysiology of chronic patellar instability, whose diagnosis and treatment remain challenging. Tibial tubercle medialisation can correct an abnormal TT-TG. Preoperative planning based on the TT-TG and trochlear angle may avoid both under-correction inducing persistent instability and overcorrection responsible for pain. Preoperative planning should be patient-specific. With appropriate preoperative planning, compensation for moderate trochlear dysplasia can be achieved without any additional procedure.

Lateral retinacular release via a prolonged incision versus arthroscopic lateral retinacular release in osteofascial medial patellofemoral ligament reconstruction for recurrent patellofemoral dislocation

Objective To compare the short-term outcomes between lateral retinacular release (LRR) via a prolonged incision versus arthroscopic LRR in osteofascial medial patellofemoral ligament reconstruction (MPFL-R) for recurrent patellofemoral dislocation. Methods From May 2012 to March 2015, 51 patients with recurrent patellofemoral dislocation were treated at the Department of Joint Surgery, The Third Affiliated Hospital to Hebei Medical University. They were 16 males and 35 females, aged from 20 to 36 years (mean 27.2 years). Of them, 28 underwent LRR via a prolonged incision in MPFL-R (incision group) and 23 did arthroscopic LRR in MPFL-R (microscopic group). Imaging changes were assessed by comparing preoperative and postoperative values of patella extensibility, patellar tilt angle, trochlear groove angle and tibial tuberosity-trochlear groove spacing (TT-TG); the knee joints were scored with Kujala and Lysholm functional rating systems at the last follow-ups. Results The 2 groups were compatible due to insignificant differences in the general data between them preoperatively (P>0.05). The 51 patients were followed up for 10 to 32 months (average, 20 months). The rate of dislocation in the incision and microscopic groups were 0 and 8.7% (2/23), respectively. There were no such complications in either group as patellar fracture, deep venous thrombosis of the lower extremity or limited joint extension or flexion. The last follow-ups revealed that no patients in either group were inflicted with patellofemoral re-dislocation. In the incision group, the patella extensibility, patellar tilt angle, Kujala score and Lysholm score were, respectively, 19.65%±0.75%, 12.39°±0.76°, 56.37±2.94 points and 51.64±6.22 points preoperatively, and 10.34%±0.60%, 8.83°±0.89°, 92.68±2.75, and 90.71±1.91 points postoperatively; in the microscopic group, the patella extensibility, patellar tilt angle, Kujala score and Lysholm score were, respectively, 19.56%±0.62%, 12.35°±0.66°, 57.46±3.08 points and 52.20±6.94 points preoperatively, and 10.24%±0.66%, 8.78°±0.92°, 92.53±3.32 points and 90.41±2.90 points postoperatively. There were significant differences between the preoperative and postoperative values in both 2 groups (P 0.05). There were no significant differences between the 2 groups in all the above preoperative and postoperative values (P>0.05). Conclusion In MPFL-R for recurrent patellofemoral dislocation, both LRR via a prolonged incision and arthroscopic LRR can improve the patellofemoral joint alignment and stability of the tibia, leading to good short-term outcomes. Key words: Arthroscopy; Patellar ligament; Patellar dislocation; Lysis

The TT-TG Distance 40 Year-Old Anniversary

Tibial tuberosity medialization could be proposed as a treatment for chronic patellar instability associated with an increased tibial tuberositytrochlear groove distance (TT-TG). TT-TG is 40 year old as it was first described by Goutallier et al. [1]. According to his further clinical researches, TT-TG should not be considered by itself when planning a tibial tuberosity medialization but correlate to the trochlear groove angle. This correlation allowed an optimization of the tibial tuberosity medialization technique by limiting the risk of persistent instability (TT not enough medialized) or pain (TT too medialized).

Tibial tubercle-trochlear groove distance and angle are higher in children with patellar instability.

The purpose of this study was to assess the variations in tibial tubercle-trochlear groove distance and angle as a function of age and gender in a population of children without patellar instability (PI) compared with those with PI. A retrospective review of 869 children's knee MRIs, ages 5 to 15years, were evaluated using a control group (792 children) without evidence of PI and a group with PI (77 children). Tibial tubercle-trochlear groove distance (TT-TGd) and angle (TT-TGa) were measured twice by two readers to assess intra- and inter-observer reliability and compared between PI and control groups. In both groups, functions of age and gender on TT-TGd and TT-TGa values were evaluated. Both TT-TGd and TT-TGa measurements showed excellent intra- and inter-observer reliability. The mean TT-TGd for the PI group was 17.2mm (SD 6.6) and significantly higher than the mean TT-TGd for the control group (10.4 SD 3.8mm, P = 0.001). The mean TT-TGa for the PI was 20.8° (SD 8.3°), which was also significantly higher than the mean TT-TGa for the control group (12.5° SD 4.6°, P < 0.001). Control group revealed a positive correlation between age and TT-TGd measurements (r = 0.243, P < 0.001). The mean TT-TGa for girls (13.3° SD 4.7°) was higher than the mean TT-TGa for boys (11.9° SD 4.4°) in the control group (P < 0.001). TT-TGa and TT-TGd are reliable and can be used for the evaluation of the extansor mechanism alignment in children with and without PI. However, it must be considered that TT-TGd is increasing in growing patients. Soft-tissue procedures may be prone to failure, since bony procedures for patellar alignment cannot be done until skeletal maturity. III.

Ultrasonography findings and physical examination outcomes in dancers with and without patellofemoral pain

ABSTRACTObjectives: To identify whether a physical examination for patello-femoral pain (PFP) is related to ultrasonography findings at the knee, and to identify possible factors related to PFP in young dancers.Methods: Sixty-seven young female dancers (7th grade, aged 12.8 ± 0.5) from three schools with identical special dance programs were included in the study. All the dancers were interviewed for demographic details, dance background, and training intensity; were evaluated for anthropometric measurements; underwent physical examination of both knees for PFP and for knee range of motion (ROM); and, had ultrasonography assessment for pathologies and of anatomical parts of their knees.Results: PFP was found in 54.5% of the 134 knees physically examined. In ultrasonography assessment, infra-articular effusion was found in 46.2% of the knees examined. H/week of dance practice was significantly higher among dancers with PFP (in both knees) compared with dancers with no PFP (p < .05). Knees with PFP had a significantly higher prevalence of intra articular effusion (p = .018) and higher prevalence of genu-recurvatum (p = .042). Knees with PFP had significantly greater growth plate width-anterior tibial tuberosity (p = .022) and a greater bony trochlear groove angle (p = .048).Conclusion: This study describes the relationship between physical examination for PFP and the sonographic findings, and the factors related to knee injuries. The results showed a high prevalence of PFP and intra articular knee effusion among young dancers at the age of 12–13 years; and, that the number of hours of practice and anatomical structure are related to PFP. Our results should alert physicians, physiotherapists, athletic trainers and dance teachers to the need for devising modifications of training and injury prevention strategies from a young age (<12 years old).

PATELLOFEMORAL ARTHROPLASTY CHANGES THE TROCHLEAR GROOVE ANGLE

High early failure rates occur in the treatment of isolated symptomatic patellofemoral arthritis with commercially available patellofemoral arthroplasty (PFA) prostheses. We postulate that PFA changes the trochlear groove angle, thereby causing patellar maltracking, catching and pain. We examined the extent of this change in trochlear groove angle by virtually implanting five commercially available patellofemoral prostheses into two 3D reconstructed knees, one with a normal and the other with a dysplastic trochlea. The axial and coronal trochlear groove angles were measured pre- and post PFA for the five different prostheses in both the normal and the dysplastic knee. Post PFA, the trochlear groove angle changed from the original in both the axial and coronal planes for all the prostheses in both the normal and the dysplastic knee. The trochlear groove change is dependent on the design of the specific prosthesis. To avoid excessive changes post PFA, both the wide variation of changes between different generic PFA prostheses, as well as the wide variation in patient femoral anatomy should be considered.

Patellar Tendon-Trochlear Groove Angle Measurement: A New Method for Patellofemoral Rotational Analyses.

Background:The tibial tubercle–trochlear groove (TT-TG) is used as the gold standard for patellofemoral malalignment.Purpose:To assess 3 patellar tendon–trochlear groove (PT-TG) angle measurement techniques and the PT-TG distance measurement (tendinous cartilaginous TT-TG) as predictors of patellar instability.Study Design:Cohort study (diagnosis); Level of evidence, 3.Methods:Three PT-TG angle measurements and the PT-TG distance were measured in 82 participants with patellar instability and 100 controls using magnetic resonance imaging (MRI). Measurement landmarks were the line tangent to the posterior femoral condyles, the deepest point of the trochlea, the transepicondylar line, and the patellar tendon center. All measurements were recorded once by 1 examiner, and the measurements were recorded twice by 2 examiners in a random group of 100 knees. Mean values and standard deviations (SDs) were obtained. Normality cutoff values were defined as 2 and 3 SDs above the mean in the control group. The sensitivity, specificity, and positive likelihood ratio (LR+) were calculated. Inter- and intrarater reliability were assessed based on the intraclass correlation coefficient (ICC).Results:The measurements from the patellar instability and control groups, respectively, for angle 1 (16.4° and 8.4°), angle 2 (31° and 15.6°), angle 3 (30.8° and 15.7°), PT-TG distance (14.5 and 8.4 mm), and patellar tilt (21.1° and 7.5°) were significantly different (P < .05). The angle measurements showed greater sensitivity, specificity, and LR+ than the PT-TG distance. Inter- and intrarater ICC values were >0.95 for all measurements.Conclusion:The PT-TG angle and the PT-TG distance are reliable and are different between the patellar instability and control groups. PT-TG angles are more closely associated with patellar instability than PT-TG distance.Clinical Relevance:PT-TG angle measurements show high reliability and association with patellar instability and can aid in the assessment of extensor mechanism malalignment. A more sensitive and specific evaluation of extensor mechanism malalignment can improve patient care by preventing both redislocation and abnormal tracking of overlooked malalignment and complications of unnecessary tibial tuberosity medialization.

Ultrasound measurements for patellofemoral pain syndrome: An inter-operator reliability study

BackgroundRadiological and ultrasound measurements are commonly used in the diagnosis of patellofemoral pain syndrome (PFPS), as no clinical tests have yet demonstrated good reliability or validity. We studied the degree of agreement between two examiners for the qualitative and quantitative criteria used for the diagnosis of PFPS.MethodologyForty-one adults with chronic anterior knee pain for over 2 months were selected consecutively in a hospital's orthopaedic department. They were referred to one junior and to one senior radiologist, who evaluated the positive or negative nature of three ultrasound criteria: the presence of a dysplasia, the distance between patellar tip and trochlear groove (PTTG) during maximal quadriceps contraction, and the cartilaginous trochlear groove (CTG) angle. Each sonographic examination was performed with the radiologist blinded to the clinical details and to the other radiologist's findings.ResultsThe Cohen's Kappa and prevalence and bias adjusted Kappa (PABAK) values were poor for the ultrasound CTG angle criterion (PABAK = 0.55; kappa = 0.52) and moderate for the ultrasound PTTG distance criterion (PABAK = 0.35; kappa = 0.36). It was not possible to calculate Kappa or PABAK values for the dysplasia criterion because of very low prevalence.ConclusionQuantitative ultrasound criteria for PFPS can be reliable if performed in a standardized manner and by trained practitioners. Only the PTTG distance criterion showed a clinically acceptable inter-operator reliability level.

Displasia da tróclea e instabilidade patelar em pacientes com síndrome de Down

ObjectiveTo analyze occurrences of trochlear dysplasia in patients with Down syndrome in the presence and absence of femoropatellar instability. MethodsEleven knees with stable patellae and thirteen with unstable patellae in patients with Down syndrome were compared. Radiographs were produced to evaluate patellar height, trochlear angle and femoropatellar congruence angle. ResultsThe prevalence ratio for a high patella between the unstable and the stable patients was 1.01 using the Insall‐Salvati index and 0.68 using the Caton‐Deschamps index. For an abnormal congruence angle, the prevalence ration was 2.04. An increased congruence angle was only found in four cases, all presenting instability. ConclusionsTrochlear dysplasia was only found in cases of instability. The trochlear groove angle and the femoropatellar congruence angle correlated with the presence of patellar instability.

Use of computed tomography to determine the risk of patellar dislocation in 921 patients with patellar instability.

The purpose of this research was to identify reliable tomographic measurements that can detect patellofemoral abnormality and allow quantification of the risk of patellar dislocation in patients with potential patellar instability. A cross-sectional study in 921 patients with anterior pain or knee instability of at least 6 months’ duration was conducted from July 2001 to December 2009. All subjects were clinically evaluated and underwent radiography and computed tomography of their knees. According to their degree of dislocating patellar dysplasia, the subjects were classified into groups for statistical comparison. There was a statistically significant difference in all measurements when the groups were compared, except for external tibial torsion angle. The most sensitive and specific measurements for determining patellar instability were the trochlear groove angle, tibial tubercle-trochlear groove distance, average patellar tilt, and average patellar height. Patients with potential patellar instability, increased tibial tubercle-trochlear groove distance, and patellar height, tilt, and deviation measurements had a greater risk for patellar dislocation. The clinical relevance of this study is to determine measurements that are able to tell us about patellar dislocation risk.

Trochlear dysplasia and patellar instability in patients with Down syndrome

ObjectiveTo analyze occurrences of trochlear dysplasia in patients with Down syndrome in the presence and absence of femoropatellar instability. MethodsEleven knees with stable patellae and thirteen with unstable patellae in patients with Down syndrome were compared. Radiographs were produced to evaluate patellar height, trochlear angle and femoropatellar congruence angle. ResultsThe prevalence ratio for a high patella between the unstable and the stable patients was 1.01 using the Insall–Salvati index and 0.68 using the Caton–Deschamps index. For an abnormal congruence angle, the prevalence ratio was 2.04. An increased congruence angle was only found in four cases, all presenting instability. ConclusionsTrochlear dysplasia was only found in cases of instability. The trochlear groove angle and the femoropatellar congruence angle correlated with the presence of patellar instability.