Patellofemoral Dislocation Research Articles

Combined medial patellofemoral and patellotibial reconstruction with soft tissue fixation in recurrent patellar dislocation

IntroductionThe medial patellofemoral and patellotibial ligaments (MPFL and MPTL) are the main passive restraints to lateral patellar translation. When nonoperative management of patellofemoral dislocations fails, surgical options can be considered to restore patellofemoral stability. Several reconstruction procedures of the MPFL with semitendinosus, gracilis, quadriceps tendon, and synthetic grafts have been described. No clear superiority of one surgical technique over another is evident. Materials and methodsPatients who suffered at least two documented episodes of unilateral patellar dislocation, confirmed radiographically and at clinical examination, underwent combined MPFL and MPTL reconstruction. Patients were regularly followed-up postoperatively at 2, 4, 8, 12, and 24 weeks, and then annually for a minimum of 2.5 years. Clinical and functional evaluations were performed using the modified Cincinnati rating system and the Kujala score, while anthropometry values including thigh volume and cross-sectional area of the thigh were measured before the operation and at the latest follow-up bilaterally. ResultsThere were 7 males and 27 females with a mean age of 26.5 ± 10.7 years (range, 13–39 years). The mean follow-up was 3.1 years (range, 2.5–4 years). The mean modified Cincinnati score Increased from 51 ± 22 preoperatively to 90 ± 19 (P = .001). The mean Kujala scores increased from 47 ± 17 preoperatively to 82 ± 17 (P = .02), with no significant differences between patients with or without osteochondral lesions (P ≥ .05), and between male and female patients (P ≥ .08). The Insall-Salvati index was 1.1 preoperatively and remained within normal range (P = .05) at the latest follow-up. ConclusionCombined reconstruction of MPFL and MPTL using an ipsilateral autologous gracilis tendon is satisfactory and effective and can be considered as suitable management option to treat recurrent dislocation of the patella. However, randomized studies are needed to compare different techniques. Study designCase series.

Moment arm function dictates patella sagittal height anatomy: Rabbit epiphysiodesis model alters limb length ratios and subsequent patellofemoral anatomical development.

Patellofemoral anatomical dysplasia is associated with patellofemoral instability and pain. The closure of the knee physis occurs at the same age as the peak incidence of patellofemoral dislocation. This study determined the effect on the patellofemoral anatomical development in a rabbit epiphysiodesis model. Twenty-four skeletally immature New Zealand White rabbits were divided into three groups (a) distal femur epiphysiodesis (FE) (b) proximal tibia epiphysiodesis (TE) (c) control; no epiphysiodesis (C) performed at 6 weeks of age. The primary endpoint was shape analysis using three-dimensional reconstructions of micro-computed tomographys (CTs) performed at 30 weeks of age. The limb length ratios (femur:tibia) were significantly different for both FE (mean 0.72, SD 0.0381, P < .001) and TE (mean 0.91, SD 0.0383, P < .001) treatment groups compared to control (mean 0.81, SD 0.0073). Patella height, as measured from the most distal point of the patella to the tibial joint surface (modified Caton-Deschamps measurement), was lower (baja) in the FE and higher (alta) for the TE, compared with the control group. Our findings suggest femoral and tibial shortening can influence the development of the patellofemoral joint, which may be dictated by moment arm function and is potentially responsible for the etiology of patella alta. Future studies are warranted to explore this association further with the view for the development of treatment options for patella alta in human patients.

Physical examination of the patellofemoral joint

Patients with a patellofemoral pain are either in an acute state after a patellofemoral dislocation or are suffering from a chronic anterior knee pain (AKP), whereas AKP might be accompanied by patellar instability without dislocation. Whereas the acute state after a dislocation is mostly clear and its examination limited, the examination of a AKP is much more complex. A profound knowledge of the anatomy, the painful structures and patellofemoral biomechanics is essential in order to find the underlying pathology within the heterogeneous and diverse etiologies. Furthermore, a meticulous and precise examination is key to find the adequate treatment for AKP.

Physical examination of the patellofemoral joint

Patients with a patellofemoral pain are either in an acute state after a patellofemoral dislocation or are suffering from a chronic anterior knee pain (AKP), whereas AKP might be accompanied by patellar instability without dislocation. Whereas the acute state after a dislocation is mostly clear and its examination limited, the examination of a AKP is much more complex. A profound knowledge of the anatomy, the painful structures and patellofemoral biomechanics is essential in order to find the underlying pathology within the heterogeneous and diverse etiologies. Furthermore, a meticulous and precise examination is key to find the adequate treatment for AKP.

High failure rate 10.8years after vastus medialis transfer and lateral release (Green's quadricepsplasty) for recurrent dislocation of the patella.

In adolescent patients with recurrent patellar dislocation, the Green's quadricepsplasty stabilizes the patella in a combination of a lateral release, a transfer of the medial head of the quadriceps onto the lateral part of the patella and an imbrication of the medial patellar retinaculum and joint capsule. This study aimed to evaluate the long-term performance, considering re-dislocations and functional outcomes. We hypothesized a high failure rate in the long term. In this single surgeon and single center study 26 knees in 23 patients (mean age 14.2years; 4-22years, 18 females) with recurrent patellofemoral dislocation underwent a vastus medialis transfer, medial reefing and lateral release as it was described by Green in 1965 with a mean follow-up 10.8years (6-24years). Clinical assessment was carried out with an IKDC-score (international knee documentation committee) and a self-assessment for each knee separately. The radiologic evaluation included measurement of the patella height, the grade of trochlear dysplasia and the sulcus angle. In 12 of 26 cases (46.2%) the patella did not re-dislocate after vastus medialis transfer and lateral release. In 11 of 26 cases (42.3%), the patients described the function of their knees as normal or nearly normal according to IKDC after the surgical treatment without any re-dislocation. In 14 of 26 cases (53.8%), the patella re-dislocated. 7 of these 14 cases underwent a revision operation. Re-dislocations occurred after a mean interval of 21months after the index procedure. In only 2 of 26 cases (7.7%) the patients returned to sports. Green's procedure to stabilize patellofemoral instabilities results in a high failure rate on the long-term and low subjective assessments. We do not recommend performing vastus medialis transfer, medial imbrication and lateral release as a standalone technique. IV.

Increasing hospital admissions for patellar instability: a national database study from 2004 to 2017

ABSTRACT Objectives Epidemiology of patellar instability is not fully characterized, as some studies have produced conflicting information or been drawn from limited populations. In this study, we used the Pediatric Health Information System (PHIS) database to examine trends in admissions for patellar instability throughout the United States. We hypothesized that there would be an increasing rate of patellar instability admissions in recent years. Secondarily, we examined how demographic factors and insurance status relate to admissions for patellar instability. Methods This study queried the Pediatric Health Information System (PHIS). Patients with ICD 9 & 10 codes 8363, 8364, 71,785, M221.0, S83.001, S83.002, S83.003, S83.004, S83.005, and S83.006, were abstracted from PHIS. We included all patients admitted with patellofemoral dislocations that were reported in the PHIS database between 1 January 2004 and 30 April 2017. The rate of patellar instability admissions was examined as well as demographic factors and insurance status. Results An estimated total of 25,413 admissions for patellar instability were identified by the search of the PHIS database; 15,444 (60.8%) were female patients and 9,966 (39.2%) were male. The adjusted number of admissions per reporting hospital significantly increased over the years studied (r = 0.775, p < 0.001), from 14.5 admissions per reporting hospital in 2004 to 86.0 admissions per reporting hospital in 2016. Of all patellar instability admissions, 55.0% were white, 20.4% were black, 1.7% were Asian, and 22.9% were unknown race. A larger number of admissions occurred in patients with insurance status other than Medicaid in every year data were collected. Conclusions Based on a PHIS database search, pediatric hospital admissions for patellar instability are steadily increasing. The majority of patients admitted for patellar instability are female, white, and have insurance other than Medicaid. Males admitted for patellar instability tended to be older than females admitted for the same. Level of evidence II

Compared outcomes 16 and 25 years after lateral wedge augmentation trochleoplasty: Rate of recurrent dislocation and progression to osteoarthritis

BackgroundLateral wedge augmentation trochleoplasty (LWAT) was the earliest described trochleoplasty technique but was gradually replaced by other methods for the treatment of patello-femoral instability with trochlear dysplasia. Data on the outcomes of this procedure in adults are limited. We therefore performed a retrospective study in patients managed by LWAT to assess (1) clinical (recurrent instability and functional scores), (2) and radiological (patello-femoral osteoarthritis) outcomes. HypothesisLWAT is associated with a low long-term rate of recurrent patello-femoral dislocation and with no risk of progression to severe patello-femoral osteoarthritis. Material and methodsBetween 1988 and 1995, LWAT was performed on 66 knees in 58 patients to treat patello-femoral instability with trochlear dysplasia. Among them, 17 knees in 13 patients were re-evaluated 16 then 25 years after surgery and were included in the study. At both time points, the following were recorded: stability, pain, the Lille patello-femoral function score, and changes in radiographic and computed tomography findings. In addition to LWAT, Insall's realignment vastus medialis advancement was performed in 4 cases, sartorius muscle transposition in 9 cases, and anterior tibial tubercle osteotomy in 10 cases. ResultsNo episodes of patello-femoral dislocation were recorded during the 25-year follow-up. The mean Lille patello-femoral function score (0 worst to 100 highest) was 90±15 (range, 48–99) after 16 years and 86±23 (range, 33–94) after 25 years. After 16 years, 8/17 knees had evidence of patello-femoral osteoarthritis, which was Iwano stage 1 in 7 cases and Iwano stage 2 in 1 case. Patello-femoral osteoarthritis was noted in 12 of 13 knees after 25 years but was mild (Iwano stage 1 or 2) in 8 cases. After 25 years, arthroplasty had been performed for 4 of the 17 knees, with 2 cases each of patello-femoral arthroplasty and total knee arthroplasty. ConclusionLWAT is a reliable procedure that provides sustained protection against patello-femoral dislocation and good functional scores when used to treat patello-femoral instability due to trochlear dysplasia. Our results do not support claims that LWAT may be associated with high rates of severe osteoarthritis even after more than 20 years. Level of evidenceIV, retrospective observational study with no control group.

The Outcomes of Isolated Lateral Release in Patellofemoral Instability: A Systematic Review and Meta-Analysis.

There have been conflicting reports regarding the outcomes of lateral release when used in the management of patellofemoral instability. This systematic review and meta-analysis therefore aims to evaluate the outcomes of isolated lateral release in the management of patellofemoral instability. The review was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. All studies that reported the outcomes of isolated lateral release for recurrent patellofemoral dislocations were included. A total of 10 publications were included, with 204 knees. All studies consistently reported a decrease in the rates of patellofemoral dislocation (odds ratio [OR] < 0.01; 95% confidence interval [CI]: <0.01-0.01) and an increase in the odds of having a good outcome (OR 0.01; 95% CI: <0.01-0.02) after lateral release. All studies also consistently reported a similar number of patients participating in sports postoperatively as compared with preinjury (OR 2.78; 95% CI: 0.53-14.68). A total of 28 (14.1%) out of 198 patients had postoperative dislocation. Of these patients, 15 required a secondary procedure for patellofemoral realignment; however, all patients who had their eventual outcomes reported still had a good outcome postoperatively. Isolated lateral release can lead to good short- to middle-term outcomes when used in the management of recurrent patellofemoral dislocations. The procedure can lead to a significantly decreased rate of recurrence of patellofemoral dislocations, a significantly increased rate of good outcomes, and a similar number of patients being able to participate in sports as compared with the number of patients participating in sports prior to having patellofemoral dislocations. An isolated lateral release could therefore potentially serve as a simple and relatively low-risk procedure that could be performed as a first-line surgical management in selected patients with patellofemoral instability, allowing them to possibly avoid a more complex and major operation. This is a Level IV study.

Distal alignment procedures for patellofemoral instability: comprehensive review of the literature.

Patellofemoral disorders are a common cause of complaint in adolescent patients. Several distal realignment procedures performed in isolation or combination with proximal alignment have been described. To clarify the role of distal alignment for patellofemoral instability, a systematic review of the literature was conducted. Two independent reviewers accessed the following databases: PubMed, Medline, CINAHL, Cochrane, EMBASE and Google Scholar. A total of 1478 patients with a mean age of 22.78years were included. The mean follow-up was 86.53 months. The average Kujala score improved from 57.66 to 82.73. The average Lysholm score improved from 63.25 to 87.87, and the average Tegner score from 3 to 4.16. VAS score improved from an average 8 to 2.56. We account a total of 46 major complications, 45 minor complications and 95 recurrences. The risk of a recurrence is 6.42%. A total of 122 additional surgeries were performed during the follow-up. This systematic review of literature suggests the importance to identify the pathological background that predisposes patients for developing patellofemoral instability and its implications for the decision-making process. The optimal treatment for patellofemoral instability should be individualized to address the specific anatomical abnormalities that contribute to patellofemoral dislocations. Distal alignments are a feasible solution to restore correct patellar biomechanics and tracking, leading to an improvement of patients' quality of life.

INCREASING HOSPITAL ADMISSIONS FOR PATELLAR INSTABILITY: A NATIONAL DATABASE STUDY FROM 2004-2017

Background: Patellar instability refers to subluxation or dislocation of the patella out of the trochlear groove of the femur. Patellar instability is classically thought to be most common in adolescent girls. Risk factors for patellar instability described in the literature include female sex, race, sports participation, personal or family history of patellar instability, ligamentous laxity, trochlear dysplasia, and other anatomic factors. However, the epidemiology of patellar instability is not fully characterized, as some studies have produced conflicting information or been drawn from limited populations. In this study, we used the Pediatric Health Information System (PHIS) database to examine trends in admissions for patellar instability throughout the United States. We believe that a national pediatric hospital database will help to illustrate trends in the epidemiology of patellar instability. We hypothesized that there would be an increasing rate of patellar instability admissions in recent years. Secondarily, we examined how demographic factors and insurance status relate to admissions for patellar instability. Methods: This study used Pediatric Health Information System (PHIS) which is a comprehensive administrative database in which more than 45 pediatric hospitals participate, including not-for-profit, freestanding, and tertiary care pediatric centers associated with the Children’s Hospital Association. Patients with ICD 9 &amp; 10 codes 8363, 8364, 71785, M221.0, S83.001, S83.002, S83.003, S83.004, S83.005, and S83.006, were abstracted from PHIS. We abstracted patient characteristics such as age, sex, race, primary source of payment, and discharge year, as well as hospital characteristics such as hospital city. We included all patients admitted with patellofemoral dislocations that were reported in the PHIS database between January 1, 2004 and April 30, 2017. A Shapiro-Wilk test was conducted to determine normality of the dataset, along with a subsequent Pearson correlation to examine the relationship between number of patellar dislocation admissions over the years studied, adjusted for number of hospitals in the study. The relationship between age at admission and sex was examined using a two sample T-test and a linear regression analysis. All statistical analyses were performed using IBM SPSS Statistics Software Version 23.0 (IBM Corp, Armonk, NY, USA). Statistical significance was set at p &lt; 0.05. Results: An estimated total of 25,413 admissions for patellar instability were identified by the search of the PHIS database; 15,444 (60.8%) were female patients and 9,966 (39.2%) were male. The adjusted number of admissions per reporting hospital significantly increased over the years studied (r=0.775, p&lt;0.001), from 14.5 admissions per reporting hospital in 2004 to 86.0 admissions per reporting hospital in 2016. Males were admitted for patellar instability at a significantly older age than females in the data extracted from the PHIS database (14.36 ± 0.23 vs. 13.58 ± 0.20 years, p&lt;0.001). Of all patellar instability admissions, 55.0% were white, 20.4% were black, 1.7% were Asian, and 22.9% were unknown race. A larger number of patellar instability admissions occurred in patients with insurance status other than Medicaid in every year that data was collected. Conclusions/Significance: Based on a PHIS database search, pediatric hospital admissions for patellar instability are steadily increasing. The majority of patients admitted for patellar instability are female, white, and have insurance other than Medicaid. Males admitted for patellar instability tended to be older than females admitted for the same. [Table: see text][Figure: see text][Figure: see text][Figure: see text][Figure: see text]

Plaster, splint, brace, tape or functional mobilization after first-time patellar dislocation: what's the evidence?

With an incidence of 5.8 per 100,000 per year, patellar dislocations are commonly seen in the emergency department. Surprisingly, there are only a few studies available that focus on the results of the different non-surgical treatment options after first-time patellar dislocation. The aim of this review is to provide an overview of the most recent and relevant studies on the rationales and results of the non-surgical treatment for first-time patellar dislocation.Patellar instability mainly affects young and active patients, with a peak incidence of 29 per 100 000 per year in adolescents. The medial patellofemoral ligament, a main passive restraint for lateral translation of the patella, is torn in lateral patellofemoral dislocations. Treatment of first-time patellar dislocation can be either conservative or surgical.There are two options in conservative management of first-time patellar dislocation: immobilization using a cylinder cast or removable splint, or, second, functional mobilization after applying a brace or patellar tape.The current available literature of conservative treatment after a first-time patellar dislocation is little and of low quality of evidence. Conclusions should be drawn with care, new research focussing on non-surgical treatment is therefore strongly needed.Cite this article: EFORT Open Rev 2019;4:110-114. DOI: 10.1302/2058-5241.4.180016

Magnetic Resonance Imaging Features of Traumatic Patellofemoral Dislocation

Acute traumatic patellar dislocations are encountered with relative frequency, making up 3% of all knee injuries. Typically witnessed in younger patients following sporting injuries, this injury can be debilitating, potentially leading to recurrent dislocation, pain, reduction in activity and patellofemoral osteoarthritis.Management of this injury remains controversial, and as such detailed magnetic resonance imaging (MRI) is increasingly recommended to help illustrate the exact nature of osteochondral and soft tissue injury, with a view to assessing the anatomical sequelae of patellar dislocation as well as the potential of recurrence and dictating the need for either conservative or surgical management in the acute setting. As such, awareness of the typical MRI findings in traumatic patellar dislocations may potentially aid in pursuing appropriate intervention for this pathology.This case describes a 33-year-old gentleman presenting to the emergency department following patellar dislocation. After failed departmental closed reduction, this patient progressed on to definitive anatomical MRI assessment followed by acute surgical intervention in the form of medial patellofemoral ligament (MPFL) repair. This case allows for both illustration and discussion of typical radiological features associated with traumatic patellar dislocation.

Patellar Tendon–Lateral Trochlear Ridge Distance: A Novel Measurement of Patellofemoral Instability

Background: Abnormalities in the trochlea-patella-tibia relationship have been shown to be risk factors for recurrent patellofemoral instability, although no current measurements quantify patellar containment in the trochlea. Standard measurements, such as tibial tubercle–trochlear groove (TT-TG) distance, do not account for the containment of the patella by the trochlea. Our goal was to develop a measurement to assess how well the trochlea contained the extensor mechanism. Hypothesis: A novel measurement describing the amount of the patellar tendon lateral to the lateral trochlear ridge (PT-LTR) would be a reliable measurement and significantly greater among patients with patellofemoral instability. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: The authors analyzed radiology records from 2005 to 2014 for patients aged 5 to 18 years with and without patellofemoral dislocations who had knee magnetic resonance imaging (MRI). Two blinded reviewers evaluated 215 MRI studies. Standard and novel morphology measurements were calculated for each knee and compared in a case-control design. Interobserver reliability of each measure was assessed by the intraclass correlation coefficient. Predictability for patellofemoral dislocation was calculated with 2-tailed independent-samples Student t tests. Discriminative capacity was calculated with receiver operating characteristic analyses and area under the curve (AUC). An optimal measurement cutoff with resultant sensitivity and specificity was calculated. Results: Standard measurements of TT-TG distance, tangential axial width of the patella (TAWP), and tangential axial trochlear width (TATW) had excellent agreement between raters; lateral femoral condyle length had good agreement; and the novel measurement—width of the tendon beyond the lateral femoral condyle (PT-LTR)—also had excellent agreement. These underwent predictability and discriminative capacity analyses. TT-TG, TAWP, TATW, and PT-LTR were significant predictors of patellofemoral instability. In receiver operating characteristic analysis, TAWP had an AUC of 0.65, below the 0.8 threshold. TATW had an AUC of 0.814 and, when <32.5 mm, was 76% sensitive and 77% specific for dislocations. TT-TG demonstrated an AUC of 0.806. TT-TG ≥13.5 mm was 76% sensitive and 76% specific for dislocations. PT-LTR demonstrated an AUC of 0.876 and, when ≥5.55 mm, was 73% sensitive and 89% specific for patellofemoral dislocation. Conclusion: PT-LTR is reliable, predictable, and discriminative for patellofemoral dislocations. This measurement had sensitivity similar to that of TT-TG but with higher specificity.

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

Effects of knee flexion and extension on the tibial tuberosity\u2013trochlear groove (TT\u2013TG) distance in adolescents

BackgroundMeasurement of the tibial tubercle–trochlear groove (TT–TG) distance is used to assess patellofemoral instability and rotation. Since patellofemoral instability and acute patellar dislocation are common among adolescents, it is important to clarify the relationship between TT–TG distance and various flexion and extension angles in asymptomatic children. The purpose of the present study was to determine how knee flexion and extension influence TT–TG-distance values measured using 3D imaging in an anatomic axial plane among asymptomatic adolescents.MethodsWe performed magnetic resonance imaging (MRI) of 26 knees in 13 adolescents (8 boys and 5 girls) of 11–17 years of age, with no known patellofemoral disorders. Imaging was performed with 3.0 T MRI with the knee at four separate angles of flexion between 0° and 30°. Measurements were made by two independent blinded raters.ResultsThe mean TT–TG distance in millimetres was 11.1–0.29 × the angle in degrees. TT–TG distance decreased with greater flexion, showing a mean decrease of 0.29 mm (SD, 0.04) per degree of increased flexion (p < 0.001). We found significant inter-observer (Pearson’s r = 0.636, p = 0.03) and intra-observer (Pearson’s r = 0.792, p ≤ 0.001) correlations. TT–TG values were not significantly correlated with age, length, weight, or body mass index. The rate of TT–TG change (change between consecutive TT–TG values/change between consecutive angles) was significantly negatively correlated with length (p = 0.014), weight (p = 0.004), and body mass index (p = 0.025).ConclusionsOur data revealed that TT–TG distance assessed in the anatomic axial plane decreased with greater flexion in adolescent. Moreover, this effect of knee angle was stronger in smaller subjects. These findings support the need for a standardized protocol for TT–TG distance measurement in adolescents.

Patellar position in patients with patellofemoral syndrome as characterized by anatomo-radiographic study

ObjectivesTo determine the prevalence of high patella in adult patients with knee pain, and to correlate patellar height with symptoms of patellar instability, episode of patellofemoral dislocation and anterior pain in the knee; and also verify the concordance correlation between the Insall-Salvati and Caton-Deschamps indices. MethodCross-sectional study analyzing the medical records of patients with knee pain, using lateral view knee radiographs with 30° degrees of flexion and computed tomography. The values of the Insall-Salvati index and the Caton-Deschamps index were used to determine the patellar height. ResultsA total of 756 records were analyzed, resulting in 140 knees studied, 39% men and 61% women. Both indices produced statistically significant associations for the occurrence of high patella and signs of instability and episodes of dislocation, but there was no significant association for anterior knee pain. The Kappa index obtained when analyzing the concordance correlation between the Insall-Salvati index and Caton-Deschamps index points to a regular association between them. ConclusionPatients with high patella present a higher prevalence of instability. Having a high patella has no significant relationship with the presence of anterior knee pain. The Insall-Salvati and Caton-Deschamps indices demonstrate a regular agreement on the presentation of patellar heights results.

Impact of five different medial patellofemoral ligament-reconstruction strategies and three different graft pre-tensioning states on the mean patellofemoral contact pressure: a biomechanical study on human cadaver knees

BackgroundThe medial patellofemoral ligament (MPFL) is the main stabiliser of the patella and thus mostly reconstructed in the surgical treatment of patellofemoral dislocation. The aims of this study were to gain a better understanding of the influence of altered MPFL graft-fixation locations and different graft pre-tensions on patellofemoral contact pressure.MethodsSix human cadaveric knee joints were placed in a six-degree-of-freedom knee simulator. Mean PFCP (mPFCP) was evaluated in knee flexion of 0, 30 and 90° using a calibrated pressure-measurement system. After data assessment of the native knee joint, five MPFL reconstruction conditions were conducted: Anatomical double bundle; non-anatomical proximal patellar; non-anatomical distal patellar; non-anatomical proximal femoral; non-anatomical ventral femoral. The gracilis graft was fixed at a defined knee flexion of 30° and pre-tensioned to 2, 10 and 20 N.ResultsKruskal-Wallis testing resulted in no mPFCP differences between the native and anatomical reconstruction states.Comparing the native and anatomical reconstruction states with the non-anatomical reconstruction states, no difference in the mPFCP both in knee extension (0°) (p>0.366) and in 30° knee flexion (p>0.349) was found. At 90° knee flexion, the following differences were identified: compared to the native knee state, the mPFCP increased after non-anatomical proximal femoral and non-anatomical ventral femoral reconstruction by 257% (p=0.04) and 292% (p=0.016), respectively. Compared to the anatomical reconstruction state, the mPFCP increased after non-anatomical proximal femoral reconstruction by 199% (p=0.042).Discussion and ConclusionsWith respect to all study findings and to restore a physiological PFCP, we recommend using the anatomical footprints for MPFL reconstruction and a moderate graft pretensioning of 2-10 N.

Patterns in Outcomes Reporting of Operatively Managed Pediatric Patellofemoral Instability: A Systematic Review and Meta-analysis

Background: Traumatic patellofemoral dislocation is a common injury in pediatric patients, and surgical treatment is often recommended. Increasingly, it has been recognized that clinical studies need to report age-appropriate treatment outcomes. However, the variability and appropriateness of outcomes reporting in the youth patellar instability literature are unknown. Purpose: To analyze the patterns of outcomes reporting in studies published in high-impact orthopaedic journals after operative management of pediatric patellar instability. Study Design: Systematic review; Level of evidence, 4. Methods: Six high-impact orthopaedic journals were searched using PubMed and EMBASE to identify studies reporting outcomes of operative management of pediatric patellar instability. Studies containing adults were excluded. Clinical and radiographic outcomes were recorded from included articles. Descriptive statistics were calculated for overall instability recurrence rates, return-to-activity rates, and changes in Kujala and Tegner scores. Results: Of 545 identified articles, 8 studies met the inclusion criteria. These studies encompassed 213 patients and 230 knees (mean age, 13.2 years; range, 4.5-18.3 years). Seven of 8 studies reported patients’ physeal status, but only 4 studies limited their outcomes reporting to patients with open physes. Two studies reported postoperative radiographic measures, and 5 studies reported preoperative radiographic findings. Six studies reported patient-reported outcome measures (PROMs). Seven unique PROMs were reported. All but one study reported complication rates and types of complications. The mean postoperative change in Tegner scores was −0.07 (range, −0.6 to 1.0). Among studies examining medial patellofemoral ligament reconstruction with adequate data, the mean return-to-activity rate was 86% (range, 81%-92%), the instability recurrence rate was 3% ± 20%, and the mean improvement in Kujala scores postoperatively was 22.1 (range, 19.9-26). Conclusion: There is a need for more pediatric-specific outcomes studies regarding operatively managed traumatic patellofemoral instability. Of the outcomes reported, both radiographic outcomes and PROMs should be standardized. Among radiographic outcomes, there is a need for more studies that report tibial tubercle–trochlear groove distances and use Caton-Deschamps and/or Blackburne-Peel indices to assess patellar height. Among PROMs, there is a need for studies that use PROMs validated in pediatric populations, such as the International Knee Documentation Committee Pediatric Form or the Hospital for Special Surgery Pediatric Functional Activity Brief Scale.

Predictors of Recurrent Patellar Instability in Children and Adolescents After First-time Dislocation.

Patellar dislocations are one of the most common knee injuries in children and adolescents and are challenging to treat. Recurrence rates are relatively high and many patients have functional limitations, even in the absence of a recurrent instability episode. The purpose of this study was to examine the risk factors in patients with first-time patellofemoral dislocations to develop a prediction model of recurrence. A single institution retrospective review of all patients with a first-time patellofemoral dislocation from 2002 to 2013 was performed. Demographic risk factors (age, sex, laterality, mechanism of injury, and history of contralateral patellar dislocation) and radiographic risk factors (increased patella height, trochlear dysplasia, and skeletal immaturity) were examined. Patella height was measured using Caton-Deschamps index (CDI). Trochlear dysplasia was assessed using the 2-grade Dejour classification and skeletal immaturity was assessed based on the distal femur and proximal tibia physis (open, closing, or closed). In total, 266 knees in 250 patients were included in the study. Of these, 222 (83.5%) were treated nonoperatively and 44 (16.5%) were treated surgically. Of the knees treated nonoperatively, 77 (34.7%) had a recurrence. Significant risk factors for recurrence on univariate analysis were age 14 years and below, history of contralateral patellar dislocation, trochlear dysplasia, skeletal immaturity, and a CDI>1.45. Multivariate analysis was performed and trochlear dysplasia and skeletal immaturity were the most significant factors with odds ratios of 3.56 and 2.23, respectively. The presence of all 4 multivariate risk factors (CDI>1.45, history of contralateral patellar dislocation, trochlear dysplasia, and skeletal immaturity) had a predicted risk of recurrence of 88%. The presence of any 3 risk factors had a predicted risk of about 75% and the presence of any 2 risk factors had a predicted risk of about 55%. Trochlear dysplasia, skeletal immaturity, CDI>1.45, and a history of contralateral patellar dislocation were all significant risk factors for recurrence in patients with first-time patellar dislocations. A predictive model for calculation of recurrence risk was developed for any combination of the different risk factors. This information is useful when counseling patients and their families after first-time patellar dislocation about prognosis and potential outcomes. Level IV-retrospective case series.

Caracterização por estudo anatomorradiográfico da posição patelar em pacientes portadores de síndrome femoropatelar

ObjectivesTo determine the prevalence of high patella in adult patients with knee pain, and to correlate patellar height with symptoms of patellar instability, episode of patellofemoral dislocation and anterior pain in the knee; and also verify the concordance correlation between the Insall‐Salvati and Caton‐Deschamps indices. MethodCross‐sectional study analyzing the medical records of patients with knee pain, using lateral view knee radiographs with 30̊ degrees of flexion and computed tomography. The values of the Insall‐Salvati index and the Caton‐Deschamps index were used to determine the patellar height. ResultsA total of 756 records were analyzed, resulting in 140 knees studied, 39% men and 61% women. Both indices produced statistically significant associations for the occurrence of high patella and signs of instability and episodes of dislocation, but there was no significant association for anterior knee pain. The Kappa index obtained when analyzing the concordance correlation between the Insall‐Salvati index and Caton‐Deschamps index points to a regular association between them. ConclusionPatients with high patella present a higher prevalence of instability. Having a high patella has no significant relationship with the presence of anterior knee pain. The Insall‐Salvati and Caton‐Deschamps indices demonstrate a regular agreement on the presentation of patellar heights results.