Patellar Height Ratios Research Articles

Radiographic Assessment of Anatomic Risk Factors Associated with Acute, Lateral Patellar Dislocation in the Immature Knee.

Acute patellar dislocation remains a common injury in both adult and pediatric patients. Non-operative management has been advocated for patients without a history of recurrent instability. Although pathologic thresholds for consideration of operative management have previously been reported in adults, it is largely unknown in children. A retrospective review of all skeletally immature patients diagnosed with acute lateral patellar dislocation who had MRI imaging were included for analysis. An age-based control group was also identified. Six radiographic measurements were compared: lateral trochlear inclination (LTI), trochlear facet asymmetry (TFA), trochlear depth (TD), tibial tuberosity–trochlear groove (TT–TG), sulcus angle (SA) and patellar height ratio. A total of 178 patients were included for analysis (study: n = 108, control: n = 70). The mean age of patients in the study and control groups was 13.7 and 12.1 years respectively (p ≤ 0.001). Study group patients had significant differences in all radiographic measurements including a decreased LTI (p < 0.001), increased TFA (p < 0.001) and SA (p < 0.001). The mean trochlear depth was 3.4 mm and 5.6 mm for patients in the study and control groups respectively (p < 0.001). Study group patients had an increased patellar height ratio (p < 0.001) and TT–TG distance (p < 0.001). Morphologic abnormalities may predispose skeletally immature patients to an increased risk of acute lateral patellar instability.

Standardization of patellofemoral morphology in the pediatric knee.

Our understanding of osseous morphology and pathology of the patellofemoral joint continues to improve with the use of magnetic resonance imaging (MRI), but a paucity of data currently exists in the pediatric population. We aim to formulate a reproducible means of quantitative assessment of patellofemoral morphology in children using MRI and to describe morphological changes based on sex and age. We identified 414 children presenting between 2002 and 2014 who obtained a knee MRI to evaluate for knee pain or clinically suspected knee pathology. After application of inclusion criteria, 144 "normal" MRIs in 131 children (71 boys, 60 girls) were included in the analysis. The following MRI measurements were recorded: lateral trochlear inclination, trochlear facet asymmetry, trochlear depth, tibial tuberosity-trochlear groove distance, sulcus angle and patellar height ratio. To assess intraobserver reliability, measurements in 30 randomly selected children were repeated. Differences between patient age and sex were assessed using independent t-tests and adjusted regression analysis. All recorded measurements had strong to very strong inter- and intraobserver reliability: lateral trochlear inclination (0.91/0.82), trochlear facet asymmetry (0.81/0.83), trochlear depth (0.83/0.90), tibial tuberosity-trochlear groove distance (0.97/0.87), sulcus angle (0.84/0.78) and patellar height ratio (0.96/0.83). When age and sex were mutually adjusted, statistically significant differences between males and females were observed in trochlear depth (P = 0.0084) and patellar height ratio (P = 0.0035). However, statistically significant age differences were found on all measurements except for lateral trochlear inclination. As expected, mean measurement values approached adult norms throughout skeletal maturation suggestive of age-dependent patellofemoral maturation. Our data verify the development of patellofemoral morphology with advancing age. We found that six of the most commonly used patellofemoral measurements in adults can be accurately reproduced regardless of age.

The effects of a dynamic patellar realignment brace on disease determinants for patellofemoral instability in the upright weight-bearing condition.

BackgroundPatellar stabilizing braces are used to alleviate pain and prevent subluxation/dislocation by having biomechanical effects in terms of improved patellar tracking. The purpose of this study is to analyze the effects of the dynamic patellar realignment brace, Patella Pro (Otto Bock GmbH, Duderstadt, Germany), on disease determinants in subjects with patellofemoral instability using upright weight-bearing magnetic resonance imaging (MRI).MethodsTwenty subjects (8 males and 12 females) with lateral patellofemoral instability were studied in an open-configuration magnetic resonance imaging scanner in an upright weight-bearing position at full extension (0° flexion) and 15° and 30° flexion with and without the realignment brace. Disease determinants were defined by common patellofemoral indices that included the Insall–Salvati Index, Caton–Deschamps Index, and the Patellotrochlear Index to determine patella height and patella tilt angle, bisect offset, and tuberositas tibiae–trochlear groove (TT–TG) distance to determine patellar rotation and translation with respect to the femur and the alignment of the extensor mechanism.ResultsAnalyses of variance revealed a significant effect of the brace with reduction of the three patellar height ratios, patella tilt angle, and bisect offset as well as TT–TG distance. Post hoc pairwise comparisons of the corresponding conditions with and without the realignment brace revealed significantly reduced patella height ratios, patella tilt angles, and bisect offsets at full extension and 15° and 30° flexion. No significant differences between the TT–TG distances at full extension but significant reductions at 15° and 30° flexion were observed when using the realignment brace compared to no brace.ConclusionsThis study suggests that the dynamic patellar realignment brace is capable of improving disease determinants in the upright weight-bearing condition in the range of 0° to 30° flexion in patients with patellofemoral instability.

The reliability of four widely used patellar height ratios.

The objective of this study was to evaluate the inter-observer reliability and the intra-observer reliability of four patellar height ratios: Insall-Salvati (IS), modified Insall-Salvati (MIS), Blackburne-Peel (BP) and Caton-Deschamps (CD). The patellar height ratios were assessed by four independent examiners using weight-bearing lateral knee radiographs in 30° flexion. Intra-class correlation coefficients and Fleiss' kappa's were determined. The inter-observer reliability was excellent for the IS and moderate for the other ratios. When the ratio values were categorized, the inter-observer reliability was strong for the IS, moderate for the MIS and BP, and poor for the CD. The intra-observer reliability was excellent for the IS, MIS and CD, and strong for the BP. When the ratio values were categorized, the intra-observer reliability was strong for the IS and MIS, and moderate for the other ratios. Although the IS showed best reliability, we advise to use the MIS as it showed the second best reliability but is, according to the literature, associated with better validity.

Effect of patient position on measurement of patellar height ratio.

Patient position is an important factor which can affect the accuracy of patellar height ratio measurement. Varying degree of knee flexion angles and action of quadriceps muscle while supine or standing positions are the most concerning factors. Forty healthy subjects had radiographs taken of their knees at 0°, 30°, and 60° of flexion in the supine (non-weight-bearing) and standing (weight-bearing) positions. Patellar height was assessed by five different measurement methods including Insall-Salvati (IS), Modified Insall-Salvati (MIS), Caton-Deschamps (CD), Blackburne-Peel (BP), and Knee triangular ratio (KT). The mean and standard deviation (SD) in the supine/standing position of each method were IS 1.0 (0.1)/1.05 (0.1), MIS 1.6 (0.2)/1.8 (0.3), CD 1.0 (0.2)/1.2 (0.2), BP 0.9 (0.2)/1.0(0.2), and KT 1(0.1)/1(0.1). Significant differences were found between supine and standing positions using all of the methods except for KT ratio. Comparisons between the various knee flexion angles were found to be statistically significant by most of the measurement methods, although the differences between the means were less than their SD. Quadriceps action had a significant influence on the mean values obtained by the MIS, CD, and BP methods. In clinical practice, interpretation for patella alta or patella baja of these measurement methods should be normalized according to the patient position. Varying the degree of knee flexion did not produce clinically important effects in any of the five patellar height measurement methods.

Imaging characteristics of contralateral asymptomatic patellofemoral joints in patients with unilateral instability.

To test the hypothesis that in patients with unilateral patellofemoral instability ( PI patellofemoral instability ), the contralateral asymptomatic joints have abnormal morphology and imaging features of osteoarthritis ( OA osteoarthritis ) at four-dimensional ( 4D four-dimensional ) computed tomography (CT). The institutional review board approved this HIPAA-compliant retrospective study. Informed consent was waived. Radiology records were reviewed to identify 25 patients (male-female ratio, 0.56; median age, 20 years; range, 13-43 years) with unilateral PI patellofemoral instability undergoing 4D four-dimensional CT and 25 age- and sex-matched control patients undergoing multidetector CT. Trochlear groove depth ( TGD trochlear groove depth ), tibial tuberosity-trochlear groove ( TT-TG tibial tuberosity-trochlear groove ) distance, and patellar height ratio ( PHR patellar height ratio ) were determined to compare morphology, and bisect offset ( BO bisect offset ) measurements were obtained to compare lateral displacement of the patella between the two groups by using the Wilcoxon rank-sum test. All images were interpreted by trained observers. Tracking patterns of the patellae were determined by obtaining BO bisect offset measurements at various flexion angles with 4D four-dimensional CT. In the contralateral asymptomatic joints, TGD trochlear groove depth (median, 3.0 mm; 95% confidence interval [ CI confidence interval ]: 2.5, 4.6; P < .0001), TT-TG tibial tuberosity-trochlear groove (median, 15 mm; 95% CI confidence interval : 12.7, 18; P = .008), PHR patellar height ratio (median, 1.17; 95% CI confidence interval : 1.09, 1.2; P = .002), and patellar lateral displacement ( BO bisect offset , 85%; 95% CI confidence interval : 76.2%, 98.2%; P < .0001) were different from measurements obtained in the control group: TGD trochlear groove depth median, 5.0 mm (95% CI confidence interval : 2.2, 7.6); TT-TG tibial tuberosity-trochlear groove median, 10.9 mm (95% CI confidence interval : 3.4, 20.7); PHR patellar height ratio median, 0.92 (95% CI confidence interval : 0.67, 1.36); and BO bisect offset median, 63% (95% CI confidence interval : 59%, 68.4%). OA osteoarthritis was detected in 40% of asymmetrical contralateral joints (10 of 25). By using 4D four-dimensional CT data, multiple regression analysis demonstrated that TGD trochlear groove depth (P = .026) and BO bisect offset measurements obtained at 30° of knee flexion (P = .047) had an association with the presence of OA osteoarthritis . Abnormal morphology and imaging features of OA osteoarthritis are relatively common in contralateral asymptomatic joints of young patients with unilateral PI patellofemoral instability .

A new reference line in diagnosing a high-riding patella on routine digital lateral radiographs of the knee

To propose a new reference line in diagnosing a high-riding patella (patella alta) on routine digital lateral radiographs of the knee. On 64 routine digital lateral radiographs of adult knees with no bone pathology or surgery and over the range of knee flexion between 1.6° and 79.1° (34.4°± 16.6°), the long axis of the superimposed egg-shaped femoral condyles was drawn and moved upward to pass through the point where the posterior contours of the femoral diaphysis and the femoral condyles meet-the posterior reference point-to become a new reference line. Any part of the patella crossing the new reference line indicated a high-riding patella. The new reference line was compared with the four most common patellar height ratios (Insall-Salvati, Grelsamer-Meadows or the modified Insall-Salvati, Caton Deschamps, and Blackburne-Peel) for the drawing time, accuracy, and reproducibility (intra- and interobserver agreement). The new reference line required approximately one-third to one-half of the drawing time compared to the most common patellar height ratios, with equal accuracy and complete reproducibility. On the contrary, the reproducibility of the most common patellar height ratios ranged from poor to moderate, with the best results for the Insall-Salvati ratio. The new reference line proved to be a very simple, accurate, and reproducible tool in diagnosing a high-riding patella. We believe that our preliminary results are an encouraging impetus to more complex research.

Assessment of the Patellar Height Ratios in Normal Adult Nigerians

Background: Patella bone is the largest sesamoid bone in the human body, it lies in the quadriceps tendon. The height of the Patella has been found to vary in some disease conditions. Ratios are therefore formulated to determine the normal values using various parameters related to the Patella bone. The aim of this study was therefore to determine the normal Patella height ratios in Nigerians from the different methods. Method:A total of 500 normal radiographs of the knee joint from different regions of Nigeria were utilized for this study. The ratios calculated were from:- (a) The Blumensaat’s line method (LP / WCBL) (b) The Install and Salvati method (LT / LP) (c) The Blackburn Peel method (A / B) Results: The mean Male Patella height ratios for the three different methods were as follows: LP / WCBL (0.97± 0.01), LT / LP (1.04 ± 0.07), A / B (0.87 ± 0.01) while that of the females were as follows: LP / WCBL (0.97± 0.01), LT / LP (1.04 ± 0.08), and A / B (0.87 ± 0.02). There was no significant differences in all the ratios (P>0.05). Conclusion: The study has re-evaluated the different methods at arriving at Patella height ratios in Nigerians. The findings are in keeping with earlier authors that irrespective of sex and race, the normal Patella height ratios do not vary and can be used for restoring knee function and kinematics in diseased states.

The patellofemoral joint: do age and gender affect skeletal maturation of the osseous morphology in children?

The osseous morphology of the patellofemoral joint is an independent factor that affects the biomechanics of patellofemoral instability. The purpose of this study is to determine age- and gender-related differences in the osseous morphology of the patellofemoral joint in children during skeletal maturation. This study was approved by the institutional review board and was HIPAA-compliant. We included 97 children and young adults (age range 5-22years; 51 girls and 46 boys, mean ages 14.3years and 13.7years, respectively). We studied 1.5-T knee MR exams, measuring the osseous morphology of the patellofemoral joint (lateral trochlear inclination, trochlear facet asymmetry, trochlear depth, patellar height ratio, tibial tubercle-trochlear groove distance, and lateral patellofemoral angle) for each MR exam. We compared measurements to published values for patellofemoral instability. Physeal patency (open or closing/closed) was determined on MR. We assessed the associations between MR osseous measurements and gender, age and physeal patency using Wilcoxon rank sum test and least square means regression models. The osseous patellofemoral joint morphology measurements were all within a normal range. There were no significant correlations between MR osseous measurements and age, gender or physeal patency. During skeletal maturation, age and gender do not affect the osseous morphology or congruency of the patellofemoral joint.

The intra- and inter-rater reliability of X-ray radiological measurements for patellar instability

AimPatellar instability is a complex, multi-factorial disorder. Radiological assessment is regarded as an important part of the management of this population. The purpose of this study was to determine the intra- and inter-rater reliability of common radiological measurements used to evaluate patellar instability. Methods and materialsOne hundred and fifty X-rays from 51 individuals were reviewed by five reviewers, two orthopaedic trainees, a radiological trainee, a consultant radiologist and an orthopaedic physiotherapist. Radiological measurements assessed included patellar shape, sulcus angle, congruence angle, lateral patellofemoral angle, lateral patellar displacement (LPD), lateral displacement measurement (LDM), boss height, and patellar height ratios. All assessors were provided with a summary document outlining the method of assessing each measurement. No further formal teaching was provided. Bland–Altman analyses were adopted to assess intra- and inter-rater reliability. ResultsThe results indicated generally low measurement error on intra-rater reliability assessment, particularly for LPD, LDM and boss height measurements. Whilst the inter-rater reliability between assessors indicated a low mean difference for assessments of patellar height measurements, patellar angle, lateral patellar dislocation and lateral displacement, wide 95% limits of agreement for all measurements indicated poor precision. ConclusionMany of the standard measurements used to assess the patellofemoral joint on plain radiographs have poor precision. Intra-rater reliability may be related to experience but it seems likely that to achieve good inter-rater reliability, specific training may be required to calibrate observers. More formal training in the technique of radiological measurement for those who were inexperienced might have improved the inter-rater reliability.

Multimodality correlations of patellar height measurement on X-ray, CT, and MRI

To investigate whether the universally accepted range of normal patellar height ratios derived from radiography for the Insall-Salvati (IS) and Blackburne-Peel (BP) methods could be similarly applied to both CT and MRI. Institutional review board approval was obtained with waiver of informed consent for this HIPPA-compliant study. A total of 45 knees in 42 patients (15 men, 27 women; age range 11 to 75 years, mean age 39 ± 20 years) who underwent tri-modality (radiograph, CT, and MRI) examinations were selected. All patients had knee imaging obtained for a variety of reasons and measurements were performed by two independent readers who were blinded to each other's measurements or the respective measurements derived from each of the methods. Paired t test was used to compare the mean values among the modalities. Inter-observer and inter-method agreements were assessed using intra-class correlation coefficients. Statistically significant, but small quantitative differences are noted between tri-modality patellar height ratios. For comparable results, the small addition of 0.13 and 0.10 are needed for the Insall-Salvati measurements on MRI and CT respectively, compared with radiographs. For the Blackburne-Peel ratio, an additional adjustment of 0.09 is needed between radiographs and MRI, but not between radiographs and CT. These adjustments are independent of gender. The interobserver reproducibility was excellent (ICC ≥ 0.94) for both the Insall-Salvati and Blackburne-Peel methods for all modalities. The results indicate that cut-off values for patella alta and baja derived from radiographs should not be directly transposed to CT and MRI; however, the adjustments are relatively minor. These measurements show excellent reproducibility for all modalities currently used for patellar height measurements.

Is Superolateral Hoffa Fat Pad Edema a Consequence of Impingement between Lateral Femoral Condyle and Patellar Ligament?

To evaluate whether knee extensor mechanism features are associated with superolateral Hoffa fat pad edema at magnetic resonance imaging. Institutional review board approval and written consent from all patients were obtained. Patients with superolateral Hoffa fat pad edema (n = 30) and a control group without edema of the fat pad (n = 60) were evaluated prospectively with magnetic resonance (MR) imaging. Demographic data and extensor mechanism features were compared, including trochlear depth, lateral trochlear inclination, patellar tilt angle, patellar height ratio, distance between patellar ligament and lateral trochlear facet, distance from the tibial tubercle to the trochlear groove, patellar facet asymmetry, and patellar ligament abnormalities. The following variables were associated with superolateral Hoffa fat pad edema in the multivariable models: patellar height ratio (P = .023), shortest distance between patellar ligament and lateral trochlear facet (P < .001), and distance from the tibial tubercle to the trochlear groove (P = .046). Of all demographic and degenerative variables, only age was significantly associated, with younger patients more likely to have superolateral Hoffa fat pad edema (P < .009). A high-riding patella, a short distance between the patellar ligament and the lateral trochlear facet, and an increased distance from the tibial tubercle to the trochlear groove are associated with superolateral Hoffa fat pad edema at MR imaging. These results are suggestive of impingement between the lateral femoral condyle and the posterior aspect of the patellar ligament in these patients.

Novel method of measuring patellar height ratio using a distal femoral reference point

Patellar height is an important factor in patellar tracking and alters the force of the patellofemoral joint reaction. Several methods for measuring patellar height ratio have been described, with no single method recognised as a gold standard. This study developed a new measurement method using a distal femoral reference, where the normal values of measurement are unaffected by varying angles of knee flexion. Eighty-five volunteers had radiographs taken of their knees at 0°, 15°, 30°, 45° and 60° of flexion in a supine position. Patellar height was assessed by five different measurement methods: Insall-Salvati (IS), modified Insall-Salvati (MIS), Caton-Deschamps (CD), Blackburne-Peel (BP) and our new method. Three independent examiners sequentially conducted all measurements under identical conditions. The normal value obtained with the method reported here was 1 ± 0.1 standard deviation (SD) (IS 1.1 ± 0.2, MIS 1.8 ± 0.25, CD 1.08 ± 0.2, BP 0.9 ± 0.2). IS and the new method tended to have better reliability in the face of varying knee-flexion angles than did CD, BP or MIS. All methods had good to excellent levels of interobserver variation (IS 0.969, new method 0.811, MIS 0.768, CD 0.735, BP 0.708). The new patellar height ratio measurement method proved to be accurate and reproducible for evaluating a normal population. This method offered the benefit of using the distal femur as a reference landmark, and, thus, the resulting measurements were not altered by varying degrees of knee flexion.

Analysis of failed surgery for patellar instability in children with open growth plates

Many surgical procedures have been proposed to treat recurrent patellar dislocation in children. In recent years, a more tailored approach considering the underlying pathology has been advocated. The aim of the study was to analyze a group of patients with recurrent patellofemoral instability after unsuccessful operative stabilization (Roux-Goldthwait procedure, lateral release, medial reefing or in combination) in childhood and adolescence. A total of 37 children and adolescents with recurrent patellofemoral instability despite previous surgery were analyzed retrospectively. Radiographic examination included AP and lateral views to assess patella alta and limb alignment. MRI was performed to evaluate trochlear dysplasia and tibial tubercle-trochlear groove (TTTG) distance. As a control group, 23 age- and sex-matched adolescents that were treated with a favorable outcome after medial reefing alone or combined with a Roux-Goldthwait procedure were analyzed. Severe trochlear dysplasia (type B-D according to Dejour) as detected on MRI scans was found significantly more often in the study group (89%) than in the control group (21%). No statistical difference of patellar height ratio (Insall-Salvati index) and TTTG distance between the two groups could be found. Of the measured parameters, only the incidence of trochlear dysplasia was increased. Trochlear dysplasia therefore seems to be a major risk factor for failure of operative stabilization of recurrent patellofemoral instability in children and adolescents. The results in children are in consensus with the literature in adults that a more tailored operative therapy including reconstruction of the MPFL and trochleaplasty has to be considered. Retrospective study, Level III.

The relationship between trochlear dysplasia and medial patellofemoral ligament rupture location after patellar dislocation: An MRI evaluation

The medial patellofemoral ligament (MPFL) and the native trochlear geometry represent two of the most critical components of patellofemoral stability. We sought to define the relationship between trochlear dysplasia and MPFL rupture location in patients with documented patellar dislocations. We hypothesized that patients with lower grades of trochlear dysplasia would have patellar based MPFL ruptures, while patients with higher grade dysplasia would have femoral-sided ruptures. We reviewed post-injury MRIs of 59 patients with documented patella dislocation. Information gathered included: type of trochlear dysplasia in the axial plane MRI, location of MPFL rupture, patellar height ratio, tibial tuberosity to trochlear groove distance (TTTG), number of dislocations prior to MRI, and time between the latest patella dislocation and the MRI. Statistical calculations utilized the Chi-Square-Test. We classified 11 cases as a dysplasia type A, 35 as a type B, 11 as a type C, and 2 cases as a trochlear dysplasia type D. In 7 patients (12%) the MPFL rupture was patella based, in 18 patients (31%) intra-ligamentous, in 33 cases (56%) femoral sided and in one case no MPFL could be identified. In contrast to our original hypothesis, the type of trochlear dysplasia does not appear to be related to the rupture location of the MPFL after patellar dislocation. According to our results, it is not possible to presume the location of the MPFL rupture based on assessment of the trochlear morphology. Therefore, a MRI is mandatory for final indication of any surgery.

Avaliação comparativa da altura patelar pós-artroplastias totais do joelho com e sem preservação do ligamento cruzado posterior

OBJETIVO: Avaliar possíveis alterações na altura da patela, pós-artroplastias totais do joelho com e sem preservação do ligamento cruzado posterior (LCP). MÉTODO: Foram analisadas radiografias pré e pós-operatórias, de 120 pacientes submetidos a artroplastias totais do joelho, realizadas no Instituto Nacional de Traumatologia e Ortopedia, no período compreendido entre janeiro de 2003 e janeiro de 2005, com implantes do tipo Johnson de plataforma rotatória. A amostra foi dividida em dois grupos, correspondendo o grupo I a exames radiográficos pré e pós-artroplastias totais do joelho com preservação do LCP (n = 60) e o grupo II, a exames radiográficos pré e pós-artroplastias sem preservação do LCP (n = 60). Para a mensuração dos valores pré e pós-operatórios foi utilizado o método de Blackburne-Peel, cujo valor normal é igual a 0,8 (± 0,2), variando, portanto, entre 0,6 e 1. RESULTADOS: O índice patelar médio pré-operatório do grupo I foi igual a 0,874 e, no grupo II, a média foi igual a 0,857. O índice médio de altura patelar pós-operatório do grupo I foi igual a 0,849, variando entre 0,54 e 1,03. No grupo II, o menor índice foi igual a 0,48, o maior igual a 0,94, sendo o índice médio igual a 0,79. A comparação dos valores pós-operatórios nos dois grupos apresentou diferença estatisticamente significativa (p < 0,05). Conclusões: Foi observada tendência à diminuição da altura patelar em ambos os grupos estudados, sendo esta mais evidente no grupo em que houve sacrifício do LCP.

Evaluation of patellar height and measurement methods after valgus high tibial osteotomy

Several controversies exist regarding the surgical difficulties and the results of total knee arthroplasty performed after failed valgus high tibial osteotomy (HTO), and the main subject is the change in patellar height that results as patella baja or infera. The purpose of this retrospective study was to evaluate patellar height after valgus HTO and the measurement methods that were actually used. Eighty-five knees that were subjected to valgus HTO were evaluated both preoperatively and postoperatively according to the Insall-Salvati Index (ISI), Blackburne-Peel Index (BPI), and Caton Index (CI) to assess any alteration of patellar tendon height that was present. All cases underwent closing wedge osteotomy with three staples or plate internal fixation and were allowed early range of motion. Significant decrease in mean patellar height ratios was detected according to all three indexes at 85 months of mean follow-up. The percentages of the decrease were 8.26% in ISI, 9.08% in BPI, and 6.34% in CI. Two knees showed patella infera according to ISI, one according to BPI and three according to CI. There were no significant correlations between the indexes and clinical status of the patients. Elevation of patella relative to the femur in closing wedge valgus HTO procedure due to the shortening of the segment between tibial tuberosity and joint line is normally expected. A significant decrease in patellar height according to ISI suggests that there should be patellar tendon shortening as patellar height cannot be changed. BPI and CI for determining patellar height in valgus HTO do not accurately measure the alteration of patella because they may affect the tibial inclination and antero-posterior translation of the proximal fragment. Another measuring system based on femoral reference points should be proposed to determine the exact change of patellar height in the valgus HTO procedure.

Patellar Height Ratios in Children

Patellar Height Ratios in Children

Patellar Height Ratios in Children

Several indices for patellar height measurement have been described to relate patellofemoral instability and maltracking. No known study has proved interobserver reliability of these indices when applied to growing knees. This study included comparisons of three of these indices: Caton-Deschamps, Blackburne-Peel, and Koshino. Three observers measured patellar height on 36 lateral radiographs of children's knees. The best interobserver agreement was achieved by the Caton-Deschamps method, a simple, reliable, and reproducible index that is not affected by skeletal maturation.

Shortening of the patellar tendon after anterior cruciate ligament reconstruction

In this prospective study, patellar height changes were investigated after anterior cruciate ligament (ACL) reconstruction with a mean follow-up of 22.4 months. A total of 114 patients were included. Fifty- two patients (group A) were treated by multiple suture repair, 27 patients (group B) underwent acute ACL reconstruction, and 35 patients (group C) underwent ACL reconstruction > or =6 weeks after injury with a patellar tendon graft. The patellar vertical height ratios (VHR) were evaluated preoperatively (VHR 1), 6 months postoperatively (VHR 2), and at follow-up (VHR 3). For the studied questions, the following answers were obtained: (1) The change of the patella height was the same in all three groups (i.e., disregarding the different surgical procedures). (2) The time elapsed between injury and ACL reconstruction did not influence the shortening of the patellar tendon. (3) Women showed a more pronounced shortening of the patellar tendon than did men. (4) A significant shortening of the patellar tendon occurred in 30% of our patients, and the process of shortening was finished 6 months postoperatively. (5) Anterior knee pain was present in 27.2% of our patients and occurred significantly more often after patellar tendon graftings. (6) Age had no influence on the changes of the patellar height. Arthroscopy 1998 Sep;14(6):592-6