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Journal of Orthopaedics 2020Patellar dislocations are a significant injury with the potential for long term problems. Little work has been done on establishing the mechanism by which this injury... (Review)
Review
BACKGROUND
Patellar dislocations are a significant injury with the potential for long term problems. Little work has been done on establishing the mechanism by which this injury occurs.
OBJECTIVES
To determine the mechanism of injury of a patella dislocation based on the available published literature and compare them to already proposed theories.
METHODS
A systematic review of the literature was conducted following searches performed on MEDLINE, EMBASE and ProQuest from the earliest year of indexing using the following search terms in any combination: "patella", "dislocation", "mechanism of injury", "anatomy", "biomechanical" and "risk factor". A broad inclusion criteria was used that included studies that looked at patellar dislocations and instability with respect to the patellofemoral joint (PFJ) kinematics or altered kinematics of the PFJ. Studies that did not address the kinematics or biomechanics of the PFJ were excluded. Studies were appraised based on their methodology using a combination of the Critical Appraisal Skills Programme tool and the Quality Appraisal for Cadaveric Studies.
RESULTS
113 studies were identified from a search of MEDLINE, EMBASE and ProQuest databases. Following application of our inclusion criteria, a total of 23 studies were included in our review. 18 of these studies were cadaveric biomechanical studies. The remaining studies were anatomical, imaging based, and a computer simulation based study.
CONCLUSIONS
These biomechanical and kinematic studies provide some evidence that a dislocation is likely to occur during early knee flexion with external rotation of the tibia and contraction of the quadriceps. There is limited evidence to support other elements of proposed mechanisms of dislocation.
PubMed: 32042233
DOI: 10.1016/j.jor.2019.11.018 -
The Journal of Knee Surgery Apr 2022Knee dislocations, aka multiligamentous injuries, are uncommon but devastating injuries often following high-energy trauma. Tears of the major knee stabilizers are well... (Review)
Review
Knee dislocations, aka multiligamentous injuries, are uncommon but devastating injuries often following high-energy trauma. Tears of the major knee stabilizers are well documented; however, injuries of the knee extensor mechanism are less commonly reported. The extensor mechanism is comprised of the patella, patellar tendon, and quadriceps tendons. Magnetic resonance imaging (MRI) is the preferred imaging modality of internal derangements of the knee due to its excellent soft tissue contrast. In this article, we will discuss the normal imaging findings of the extensor mechanism and review abnormalities following knee dislocation.
Topics: Humans; Knee Dislocation; Knee Injuries; Knee Joint; Patella; Patellar Ligament; Tendon Injuries
PubMed: 35226944
DOI: 10.1055/s-0042-1743224 -
Indian Journal of Orthopaedics Apr 2021Habitual dislocation of patella is an uncommon pathological condition. Though numerous techniques have been described in the literature for the treatment of patellar...
AIM
Habitual dislocation of patella is an uncommon pathological condition. Though numerous techniques have been described in the literature for the treatment of patellar dislocations, none of the single procedure is fully effective in the surgical treatment of habitual dislocation of patella. We described our experience with a two in one procedure for habitual dislocation of patella in ten children.
PATIENTS AND METHOD
Ten children having habitual dislocation were reviewed prospectively for twelve months following surgical procedure. The age ranged between 5 and 9 years. We performed graded lateral soft tissue release and patellar tendon transposition as described by Roux Goldthwait. Clinical results were evaluated using Kujala score, ability to do straight leg raise, knee range of motion and visual analogue scale.
RESULT
There has been no recurrence of dislocation. The mean Kujala score before surgery was 48 which improved to 97.8 at 12 months follow-up after the surgical procedure. At 12 months follow-up all patients were able to do straight leg raise and had almost full range of motion.
CONCLUSION
We conclude that extensive proximal lateral release along with Goldthwait Roux procedure helps in treating the habitual dislocation in patella in children. Decision for the extent of lateral release must be taken intra-operatively. Our method of treatment is simple, cost effective and reproducible with excellent functional outcome.
PubMed: 33912326
DOI: 10.1007/s43465-020-00114-6 -
Journal of Personalized Medicine Aug 2023The patellofemoral joint (PFJ) is a complex articulation between the patella and the femur which is involved in the extensor mechanism of the knee. Patellofemoral...
The patellofemoral joint (PFJ) is a complex articulation between the patella and the femur which is involved in the extensor mechanism of the knee. Patellofemoral disorders can be classified into objective patellar instability, potential patellar instability, and patellofemoral pain syndrome. Anatomical factors such as trochlear dysplasia, patella alta, and the tibial tuberosity-trochlear groove (TT-TG) distance contribute to instability. Patellofemoral instability can result in various types of dislocations, and the frequency of dislocation can be categorized as recurrent, habitual, or permanent. Primary patellar dislocation requires diagnostic framing, including physical examination and imaging. Magnetic resonance imaging (MRI) is essential for assessing the extent of damage, such as bone bruises, osteochondral fractures, and medial patellofemoral ligament (MPFL) rupture. Treatment options for primary dislocation include urgent surgery for osteochondral fragments or conservative treatment for cases without lesions. Follow-up after treatment involves imaging screening and assessing principal and secondary factors of instability. Detecting and addressing these factors is crucial for preventing recurrent dislocations and optimizing patient outcomes.
PubMed: 37623475
DOI: 10.3390/jpm13081225 -
Acta Orthopaedica Et Traumatologica... Sep 2022Videos uploaded to YouTube do not go through a review process, and therefore, videos related to patellofemoral instability may have little educational value. The purpose...
OBJECTIVE
Videos uploaded to YouTube do not go through a review process, and therefore, videos related to patellofemoral instability may have little educational value. The purpose of this study was to assess the educational quality of YouTube videos regarding patellofemoral instability.
METHODS
A standard search was performed on the YouTube database using the following terms: "unstable kneecap," "patellar instability," "patellofemoral instability," "kneecap dislocation," and "patellar dislocation," and the top 50 videos based on the "relevance" assignment of the YouTube algorithm were included for analysis. The properties, content, and source of each video were recorded. The educational quality of videos was analyzed according to scores obtained using DISCERN, the criteria of Journal of the American Medical Association, Global Quality Score, and Patellofemoral Instability Specific Score, and the quality of the videos was evaluated according to the groupings of these scoring systems.
RESULTS
A total of 250 videos were identified, of which 89 were included in the study for analysis. The mean video duration was 11.72 ± 22.03 minutes. The median number of views was 4516.5 (range, 3-6 044 971). The content of the videos was disease-specific in 60%, 20% were related to surgical technique or approach, and 14.1% were exercise videos. Most of the videos were uploaded by physicians (33.7%). The Global Quality Score and DISCERN scores were significantly correlated with video duration. The Patellofemoral Instability Specific Score was significantly correlated with video duration, number of views, view rate, likes, and Video Power Index. According to the DISCERN classification, 69.9% of the videos were very insufficient or insufficient. According to the Patellofemoral Instability Specific Score, 65.2% of videos were evaluated as very low or low. According to the Global Quality Score, 60.7% of videos were rated as poor quality.
CONCLUSION
The quality of YouTube videos about Patellofemoral instability is insufficient. It was found that viewers tend to watch short and low-quality videos.
Topics: United States; Humans; Social Media; Information Dissemination; Video Recording; Joint Instability; Patellofemoral Joint; Reproducibility of Results
PubMed: 36250878
DOI: 10.5152/j.aott.2022.22005 -
Patellar Height Correlates Modestly With Trochlear Dysplasia: A Magnetic Resonance Imaging Analysis.Arthroscopy, Sports Medicine, and... Jun 2022To evaluate whether there is a correlation between the position of the patella and trochlear morphology in patients with and without patellar instability using...
PURPOSE
To evaluate whether there is a correlation between the position of the patella and trochlear morphology in patients with and without patellar instability using exclusively MRI measurements.
METHODS
MRI scans of knees in patients with patellofemoral instability and knees of patients with an ACL (anterior cruciate ligament) tear as a control group were reviewed. Measurements of patellar position (Canton-Deschamps ratio, Patellar Trochlear Index, and lateral patellar inclination) and trochlear morphology (lateral trochlear inclination and sulcus angle) were obtained from each scan. Bivariate and multivariate analysis was performed to identify correlations between study group, demographics, and patellofemoral joint measurements.
RESULTS
There were 70 knees in the patellofemoral instability group and 60 knees in the control group. Bivariate analysis showed a significant difference in all measurements between the patellar instability group and the control group. Multivariate analysis showed modest correlations between patellar position and trochlear morphology. The Caton-Deschamps (CD) ratio correlated with patellar trochlear index ( < .001) and lateral trochlear inclination ( < .001). The respective R-square goodness of fit was 41.1%. Patellar trochlear index correlated with CD ratio ( < .001), lateral trochlear inclination ( < .001), lateral patellar inclination ( < .001), and patellar instability group ( = .011). The R-sq goodness of fit was 37.3%. Lateral patellar inclination correlated with patellar trochlear index ( < .001), Lateral trochlear inclination ( < .001), and age at first dislocation or injury ( = .02). The R-sq goodness of fit was 68.56%.
CONCLUSIONS
Using MRI-based measurements of the patellofemoral joint, we identified modest, but significant, correlations between measures of patellar height (patellar trochlear index, CD ratio, and lateral patellar inclination) and trochlear dysplasia. This correlation is unclear and is likely multifactorial, but on the basis of this work, a causal relationship between trochlear dysplasia and patella alta cannot be established.
CLINICAL RELEVANCE
Radiographic evaluation of the patella and how it relates to the surrounding boney anatomy provides important information regarding our understanding of patella instability and its treatment.
PubMed: 35747649
DOI: 10.1016/j.asmr.2022.02.009 -
Maedica Jun 2020Recurrent patellofemoral dislocation (RPD) is a disabling condition with a variety of anatomical risk factors. Its management remains difficult and controversial....
Correlation between Patellar Tilt Angle, Femoral Anteversion and Tibial Tubercle Trochlear Groove Distance Measured by Computer Tomography in Patients with non-Traumatic Recurrent Patellar Dislocation.
Recurrent patellofemoral dislocation (RPD) is a disabling condition with a variety of anatomical risk factors. Its management remains difficult and controversial. Patients with RPD are known to have increased femoral anteversion (FA) and tibial tubercle trochlear groove (TT-TG) distance, but their effect on the patellar tilt angle (PTA) is less studied. The aims of this study are to compare PTA, TT-TG distance and FA between RPD patients and healthy controls and to establish a relation between these parameters and the type of surgery indicated for this pathology. A total of 63 knees (57.1% females, 28.1±6.2 years), of which 33 from subjects with RPD and 30 from healthy controls, were assessed by computed tomography (CT) scan under supine position, with the measurement of TT-TG distance, FA and PTA. The values of PTA, FA and TT-TG distance were significantly higher in the RPD group compared to the control group (CI 95% 9.52-11.64, CI 95% 5.87-11.8, CI 95% 6.44-9.72, respectively, with p value <0.0001 in all cases). In the RPD group, PTA significantly correlated to the FA (r=.53, p=0.001) and TT-TG (r=.39, p=0.02), while TT-TG correlated to FA (r=.53, p=0.001) too. Further analysis in the RPD group showed a significant correlation of PTA, FA and TT-TG (r=.96, r=.89, respectively, p=0.0001) when FA >25 degrees, but no significant correlation between TT-TG and FA or PTA when FA<25 degrees. Moreover, higher values of PTA and FA positively correlated with TT-TG distance (r=.44, r=.74, r=.20, p=0.03) when TT-TG was >20 mm, but no correlations were found between TT-TG and FA on less than 20 mm. In patients with RPD, FA, TT-TG and PTA have significantly higher values than controls. Higher PTA, TT-TG and FA are associated with an anteversion angle greater than 25 degrees and a TT-TG distance more than 20 mm, which might indicate a derotational femoral osteotomy to these patients in order to correct this pathology.
PubMed: 32952681
DOI: 10.26574/maedica.2020.15.2.174 -
Orthopaedic Journal of Sports Medicine Dec 2022Patellar dislocation is a common injury in children and adolescents. There is a lack of information about concomitant osteochondral lesions in these patients.
BACKGROUND
Patellar dislocation is a common injury in children and adolescents. There is a lack of information about concomitant osteochondral lesions in these patients.
HYPOTHESIS
We hypothesized that the likelihood of chondral or osteochondral lesions would increase with each prior patellar dislocation and that the appearance of lesions in surgically treated children and adolescents would be influenced by age, sex, injury mechanism, and body mass index (BMI).
STUDY DESIGN
Case-control study; Level of evidence, 3.
METHODS
Inclusion criteria were (1) age <18 years, (2) surgical treatment with diagnostic arthroscopy of the knee including description of chondral and osteochondral lesions, and (3) maximum time period between the last patellar dislocation and presentation in our department of 6 weeks and maximum of 4 weeks between presentation and surgery. A total of 153 children (173 knees) with a mean age of 13.0 ± 2.1 years were included. All surgical reports and intraoperative arthroscopic imaging were analyzed retrospectively for the location and severity of lesions. The likelihood of lesions was calculated with multiple stepwise regression models regarding injury mechanism, number of dislocations, sex, age, physeal closure, and BMI.
RESULTS
The regression model to predict femoral lesions was statistically significant (χ[5] = 26.55; < .001) and identified male sex, BMI ≥25, traumatic injury mechanism, and physeal closure as independent factors associated with the appearance of femoral lesions. The second regression model predicting the appearance of patellar lesions was also statistically significant (χ[4] = 26.07; < .001) and identified the traumatic injury mechanism as a single independent predictor for patellar lesions.
CONCLUSION
BMI ≥25, male sex, and physeal closure were factors significantly associated with femoral chondral and osteochondral lesions in our cohort. In case of traumatic lateral patellar dislocation (LPD), the likelihood of patellar and femoral chondral and osteochondral lesions is significantly higher than in nontraumatic LPD. Early magnetic resonance imaging and surgical treatment should be considered in obese patients, male patients, and patients with physeal closure and after traumatic LPD.
PubMed: 36504671
DOI: 10.1177/23259671221134102 -
Journal of ISAKOS : Joint Disorders &... Dec 2023To assess the inter- and intra-rater reliability of the classification of the J-sign as "large" versus "small or none" as compared to another two-level system ("present"...
OBJECTIVES
To assess the inter- and intra-rater reliability of the classification of the J-sign as "large" versus "small or none" as compared to another two-level system ("present" versus "absent") and a three-level system ("large," "small," or "none") and to identify anatomical and patient factors associated with the presence of a large J-sign.
METHODS
Forty patients (40 knees) with recurrent patellar instability were prospectively enrolled and recorded on video actively extending their knee while seating. Four raters classified patellar tracking on two separate occasions using three systems: 1) two groups: J-sign versus no J-sign; 2) three groups: large J-sign, small J-sign, or no J-sign; and 3) two groups: large J-sign versus small or no J-sign. The intra- and inter-rater reliability of each system was assessed using kappa statistics. Anatomical (trochlear dysplasia, tibial tubercle-trochlear groove (TT-TG) distance, patellar height) and patient (Beighton score) factors as well as Knee Injury and Osteoarthritis Outcome Score (KOOS) subscales were compared between patients with a large J-sign and patients with a small or no J-sign.
RESULTS
Inter- and intra-rater reliability were found to be highest with the two-level classification system of a large J-sign versus a small or no J-sign (inter-rater kappa = 0.76, intra-rater kappa = 0.75). Patients with a large J-sign had more severe trochlear dysplasia as assessed with the sulcus angle (p = 0.042) and were more likely to have a tight lateral retinaculum (p = 0.032) and an elevated Beighton score (p = 0.009). No significant differences in KOOS subscales were noted based on the presence of a large J-sign versus a small J-sign or no J-sign.
CONCLUSION
Qualitative visual assessment of patellar tracking with the J-sign demonstrates substantial inter- and intra-rater reliability, particularly when utilizing a two-group classification system to identify knees with a large J-sign. Patients with a large J-sign demonstrate an increased incidence of a tight lateral retinaculum, generalized ligamentous laxity, and trochlear dysplasia.
LEVEL OF EVIDENCE
Level III - cross-sectional study.
Topics: Humans; Patellar Dislocation; Patellofemoral Joint; Joint Instability; Reproducibility of Results; Cross-Sectional Studies
PubMed: 37499874
DOI: 10.1016/j.jisako.2023.07.006 -
Orthopaedic Journal of Sports Medicine Jan 2021Lateral patellar dislocation can become a recurrent problem after the first episode. Identifying those patients who are at increased risk of redislocation is important...
BACKGROUND
Lateral patellar dislocation can become a recurrent problem after the first episode. Identifying those patients who are at increased risk of redislocation is important for the treatment decision-making process.
PURPOSE
To identify clinical and radiologic risk factors for recurrence of patellar dislocation after a first episode.
STUDY DESIGN
Case-control study; Level of evidence, 3.
METHODS
The study included patients with lateral patellar dislocation and a 1-year minimum follow-up who were seen between 2011 and 2018. Patients aged 10 to 65 years were included. Patient characteristics, physical examination (patellar apprehension, J sign), and radiographs were reviewed. The Caton-Deschamps and Insall-Salvati ratios were used to evaluate patella alta. High-grade trochlear dysplasia was defined as Dejour types B, C, and D.
RESULTS
A total of 130 patients (139 knees) with primary lateral patellar dislocation were included. Recurrent dislocation was seen in 83 knees (59.71%). Stepwise logistic regression analysis demonstrated that Caton-Deschamps ratio ≥1.15 (OR, 2.39; 95% CI, 1.09-5.22; = .029), age <21 years (OR, 2.53; 95% CI, 1.11-5.77; = .027), and high-grade trochlear dysplasia (OR, 4.17; 95% CI, 1.90-9.17; < .001) were significantly associated with patellar redislocation. Based on the presence of these factors, the probability of dislocation after a first lateral patellar dislocation was 31.2% with no factors present, 36.6% with any 1 factor present, 71.7% with any 2 factors present, and 86.2% if all 3 conditions were present.
CONCLUSION
The results of this study indicated that patella alta, high-grade trochlear dysplasia, and age <21 years were independent risk factors for patellar redislocation after a first episode, with an additive effect when they were present together. This may help to guide the type of treatment for these patients.
PubMed: 33614800
DOI: 10.1177/2325967120981636