Plateau-patella Angle Research Articles

Evaluation of the Tibial Plateau-Patella Angle (TPPA) in Dogs.

Estimating a dog's patellar position involves various methods, which categorize it as norma, alta (high), or baja (low). However, they require various calculations. We aimed to evaluate the clinical applicability of a new method, the tibial plateau-patella angle (TPPA). This could aid in planning patella luxation surgery, estimating the patella position after TPLO and various osteotomies. We conducted a two-step study: first, on 15 stifles without pathologies from nine canine cadavers, and second, using 100 patient X-rays from the archive. Three stifle angle positions (45 ± 5°, 90 ± 5°, and 135 ± 5°) and three weight groups (S, M, and L) were evaluated in the first part of this study. Based on these results, the second part of this study was conducted using 100 pathology-free radiographs at the optimal stifle angle (90 ± 5°) from the archive. All radiographs were measured by three observers with varying levels of experience. Our results indicate that the stifle angle significantly impacted the TPPA, whereby lower values were detected with higher stifle angles, which remained consistent within the weight groups. High inter- and intra-observer agreement was achieved. The physiological TPPA values ranged from 26.7° to 48.8°, remaining consistent within the various weight groups. Observer 3 in Group S exhibited a 20% (insignificant) deviation, possibly due to challenges in determining the caudal point of the tibial plateau. In contrast with humans, TPPA values in dogs are negatively correlated with stifle angles, independent of weight. Our reliable and reproducible protocol suggests the potential benefits of training on small-breed dogs stifles.

A new and simple method for patellar height measurement: Fibula-condyle-patella angle.

This study aims to evaluate the inter-observer reliability of fibula-condyle-patella angle measurements and to compare it with other measurement techniques. Between January 01, 2023 and January 31, 2023, a total of 108 patients (20 males, 88 females; mean age: 47.5±12.0 years; range, 18 to 72 years) who underwent X-rays using the fibula-condyle-patella angle, Insall-Salvati, Caton-Deschamps, Blackburne-Pell, and plateau-patella angle (PPA) methods were retrospectively analyzed. Knee lateral radiographs taken in at least 30 degrees of flexion and appropriate rotation were scanned. All measurements were made by two orthopedic surgeons who were blinded to measurement methods. Right knee patellar height measurements were conducted in 56 patients, while left knee patellar heights were assessed in 52 patients. The highest inter-observer concordance was found in the fibula-condyle-patella angle. The second highest concordance was found in the Insall-Salvati. The highest concordance correlation was found with PPA in the measurements of both researchers. The fibula-condyle-patella angle is a reliable technique with a good inter-observer reliability for measuring patellar height. We believe that this study will inspire future research to establish comprehensive reference values for clinical applications.

Evaluation of modified and newly applied patella height indices in primary total knee arthroplasty

ObjectiveThe aim of this radiological study was to compare several relevant modified and newly applied patella height indices (PHI) in navigated primary total knee arthroplasty (TKA) to determine intra- and interobserver reliability in order to give a recommendation for clinical application in measuring patella height (PH) in primary TKA.Materials and methodsA retrospective data analysis assessing different PHI (modified Insall-Salvati index (mISI), Caton-Deschamps index (mCDI), Blackburne-Peel index (mBPI), Plateau-Patella Angle (mPPA); Miura-Kawaramura index (MKI), Knee-Triangular index (KTI)) on lateral knee radiographs was performed by two blinded observers using the same software three months pre- and postoperatively. Concordance correlation coefficient and Pearson’s correlation respectively were determined for intra- and interobserver rating as well as a categorization according to Landis and Koch and Cohen.ResultsA total of 337/291 patients of a 5-year period could be analyzed pre-/postoperatively. Excellent postoperative interrater results according to the categorization of Landis and Koch were achieved for the mBPI (Pearson 0.98) > mPPA (0.90) > KTI (0.86), good results for the MKI (0.79) and the mCDI (0.69), and moderate results for the mISI (0.52) with a predominantly strong Cohen correlation in almost all cases. Preoperatively, the mBPI and the KTI were the best interrated PHI. No PH changes could be found postoperatively for the mISI, KTI, MKI, and mPPA.ConclusionThe mBPI, the mPPA, and the KTI can be recommended for PH assessment in TKA. The mPPA might be the easiest one to use in a daily clinical set-up.

Variables affecting patellar height in patients undergoing primary total knee replacement

BackgroundAlteration of patellar height is commonly encountered in total knee arthroplasty (TKA), and failure to address patella baja can result in suboptimal functional outcomes. It may therefore be prudent to evaluate pre-operative patellar height (PPH) and to seek risk factors for patella baja.MethodsTwo hundred eighty-five patients who underwent TKA were included. Patient’s age, gender, body mass index (BMI), and history of prior arthroscopy were recorded. PPH was measured using plateau-patella angle (PPA) as well as the Blackburn-Peel (BP), Caton-Deschamps (CD), and Insall-Salvati (IS) ratios.ResultsThe average patients’ age was 71 years with a mean BMI of 30.45. There were 191 female and 94 male patients. One-fourth of the cases had at least one prior knee arthroscopy. Multivariate linear regression analysis identified gender and BMI as variables significantly affecting the IS ratio (p: < 0.05). Gender also had a significant correlation with PPA. Male patients were likely to have lower PPA (p: < 0.03). Though increasing age had a positive correlation with patellar height, this was not statistically significant. History of prior arthroscopy had no significant effect on any of the four PPH measurements.ConclusionLower patellar height is significantly correlated to male gender and high BMI. We suggest that obese male patients be screened for pre-operative patella baja. This can help in surgical planning and optimizing results in TKA.

Literature review of acquired patella baja

Patella baja is one of the complications after total knee arthroplasty (TKA). It refers to an abnormal location of patella occurred secondary to shortening of the patellar tendon or distal positioning of the patella relative to the femoral trochlea. Clinically, it can be classified into congenital, acquired, and a combination of the above two types. Acquired patella baja is the most common type and usually occur as a result of trauma or surgery. Acquired patella baja is also caused by elevation of the joint line after TKA, which refers to pseudo-patella baja. Presently, its etiology is still uncertain. Some studies report the following causes of patella baja, including extending of quadriceps femoris, contracture of patella tendon or patellar fat pad, and fibrosis of joint. The diagnosis is mostly based on the lateral roentgenogram. The following parameters, including Insall-Salvati ratio, Modified Insall-Salvati ratio, Blackburne-Peel ratio, Caton-Deschamps ratio and Plateau-Patella angle, are used to assist diagnosis for patella baja. With the progress of imageology, some literatures describe several methods based on magnetic resonance imaging (MRI). However, the diagnostic methods of patella baja are not entirely precise. Patella baja can lead to decreased range of motion (ROM), a decreased lever arm, impingement of the patella against the tibial polyethylene or tibial plate, which may result in anterior knee pain, rupture of the patellar or quadriceps tendons. The treatment of patella baja depends on determining the cause and distinguishing between patella baja and pseudo-patella baja. Patients with severe symptom or failed for conservative treatment should receive surgery. The corrective measures for patella baja include lengthening of the patellar tendon and proximalize osteotomy of tibial tuberosity. In addition, the therapies for pseudo-patella baja include reestablishing the joint line by use of distal femoral augment, replacement of the patellar implant or polyethylene insert.

Tourniquet application during TKA did not affect the accuracy of implant positioning: a randomized clinical trial.

The accuracy of the identification of anatomical landmarks with versus without tourniquet application and its effect on implant positioning remained unknown. Therefore, the hypothesis of the present study was that tourniquet application did not affect the accuracy of the reconstruction of the mechanical leg alignment, the joint line level, and the patellar height. The prospective randomized monocentric trial (Clinical-Trials.gov NCT02475603) included a total of 86 patients scheduled to undergo primary TKA. The patients were allocated to receive TKA with (Group A, n = 43) or without tourniquet (Group B, n = 43). The mechanical leg alignment, the joint line level (modified Kawamura), and the patellar height (Plateau-patella angle, Insall Salvati index, and modified Insall Salvati index) were measured pre- and postoperatively on standardized calibrated digital radiographs. Mean, SEM, median, range, and p value were calculated for each parameter. There was no statistical difference between the groups with regard to demographics, preoperative deformity, implant design, and surgical technique (n.s.). The mechanical leg alignment, the joint line level, and the patellar height revealed, in both groups, similar results pre- and postoperatively (n.s.). The mechanical leg alignment, the joint line level, and the patellar height could be accurately reconstructed with and without tourniquet use. With respect to clinically relevant surrogate parameters of implant positioning, TKA can safely be performed without a tourniquet. Available data do not support a routine use of tourniquet during TKA and might justify a change of the clinical pathway. Level I.

Plateau–patella angle: An option for the evaluation of patellar height in patients with patellar instability

BackgroundPatellar instability is a debilitating disease. An important factor related to recurrent dislocation is patellar height. A new method of patellar height measurement, the plateau–patella angle (PPA), was proposed in 2011. However, to date, there is no study evaluating the use of this method in patients with patellar instability. The aim of this study was to evaluate the PPA in patients with recurrent patellar dislocation. MethodsThis was a retrospective evaluation of the radiographs of 78 knees with patellar instability. Patellar height was measured using the Insall–Salvati (I/S), Caton–Deschamps (C/D) and Blackburne–Peel (B/P) indices and the PPA. The qualitative and quantitative correlations between the various methods and between observers were calculated. ResultsThe PPA had a Pearson correlation of 0.76 (P<0.001) with the I/S index, 0.78 (P<0.001) with the C/D index and 0.90 (P<0.001) with the B/P index. In the qualitative correlation using the Spearman coefficient, the PPA had a correlation of 0.52 (P<0.001) with the I/S index, 0.72 (P<0.001) with the C/D index and 0.70 (P<0.001) with the B/P index. The correlations between the conventional methods were as follows: 0.57 (P<0.001) between the I/S and C/D indices; 0.61 (P<0.001) between the I/S and B/P indices; and 0.73 (P<0.001) between the C/D and B/P indices. ConclusionThe determination of the PPA is a reproducible method that is consistent with the methods currently used to measure patellar height in patients with recurrent patellar dislocation.

PLATEAU-PATELLA ANGLE: AN OPTION FOR ASSESSING PATELLAR HEIGHT ON PROXIMAL TIBIA OSTEOTOMY

ABSTRACTObjective: To compare the plateau-patella angle method to the methods already established for patellar height measurement in patients undergoing high tibial osteotomy.Methods: This is a retrospective study of 13 patients undergoing medial opening tibial osteotomy. The patellar height was measured in pre and post-operative radiographs by the methods from Insall-Salvati, Caton-Deschamps, Blackburne-Peel and patella-plateau angle, as well as the tibial slope and length of the patellar tendon. Measurements were performed by two knee surgeons at two different times.Results: The mean age was 41.33 ± 01.09 years old. The average rates of Caton-Deschamps, Blackburne-Peel, Insall-Salvati and plateau-patella angle were, respectively, 1.00; 0.89; 1.10; and 23.15° preoperatively, and 0.89; 0.78; 1.11; and 20.46°, postoperatively. The correlation of Caton-Deschamps, Blackburne-Pell, and Insall-Salvati indexes and plateau-patellar angle interobserver was 0.72 (p <0.001), 0:54 (p <0.001), 0.65 (p <0.001), and 0.67 (w <0.001), respectively.Conclusion: The plateau-patella angle method undergoes changes that are correlated with changes in tibial slope after osteotomy, unlike the classical methods. This fact may lead to overestimate the reduction of patellar height after osteotomy. Level of evidence IV. Case Series.

Comparative evaluation of patellar height methods in the Brazilian population

ObjectiveThe methods most used for patellar height measurement were compared with the plateau–patella angle method. MethodsA cross-sectional study was conducted, in which lateral-view radiographs of the knee were evaluated using the three methods already established in the literature: Insall–Salvati (IS), Blackburne–Peel (BP) and Caton–Deschamps (CD). These were compared with the plateau–patella angle method. One hundred and ninety-six randomly selected patients were included in the sample. ResultsThe data were initially evaluated using the chi-square test. This analysis was deemed to be positive with p<0.0001. We compared the traditional methods with the plateau–patella angle measurement, using Fisher's exact test. In comparing the IS index with the plateau–patella angle, we did not find any statistically significant differences in relation to the proportion of altered cases between the two groups. The traditional methods were compared with the plateau–patella angle with regard to the proportions of cases of high and low patella, by means of Fisher's exact test. This analysis showed that the plateau–patella angle identified fewer cases of high patella than did the IS, BP and CD methods, but more cases of low patella. In comparing pairs, we found that the IS and CD indices were capable of identifying more cases of high patella than was the plateau–patella angle. In relation to the cases of low patella, the plateau–patella angle was capable of identifying more cases than were the other three methods. ConclusionsThe plateau–patella angle found more patients with low patella than did the classical methods and showed results that diverged from those of the other indices studied.

High Tibial Valgus Osteotomy: Closing, Opening or Combined? Patellar Height as a Determining Factor

BackgroundAccording to the literature, closing and opening wedge high tibial valgus osteotomies can raise or lower the patella, and diffèrent methods of patella height measurement show similarly conflicting results. Clarification of this was thought to be important because there is much literature describing morbidity secondary to patella alta or patella infera (baja). Effects on tibial slope and patellar tendon length are not well delineated and the influence of sex and age is unknown.Questions/purposeA group of patients who underwent high tibial valgus osteotomy was investigated to determine how surgical technique influenced postoperative (1) patellar height and (2) tibial slope and patellar tendon length, and (3) whether age or gender independently influenced postoperative patellar height. To eliminate the often conflicting results seen when several ratio methods are used, patellar height was measured by one method, before and after surgery, shown previously to be reliable.MethodsPatellar height was measured on radiographs using the plateau-patella angle in a retrospective case series consisting of three cohorts: 18 patients with closing wedge osteotomies, 26 with opening wedge osteotomies, and 32 with combined osteotomies. The indication for surgery in all three cohorts was medial osteoarthritis with secondary varus. Before surgery there were no significant differences in patellar height, femorotibial angle, age, or gender among the three groups, and no patients were lost to followup during the 8-week study period after surgery. Seven of the 76 patients (9.2%), all in the opening wedge cohort, had concomitant ACL reconstruction at the time of the tibial osteotomy. No other surgery, except arthroscopy, was performed at the time of osteotomy. Patellar tendon length was assessed by the Insall-Salvati index and tibial slope by the angle between the posterior tibial cortex and the medial tibial joint line. Postoperative measurements were made between 6 and 8 weeks. The influence of sex and age was calculated using patellar height measurements made before any surgery.ResultsAll closing wedge osteotomies produced patellar ascent by an average of 13% (p < 0.001), all opening wedges produced descent by an average of 21% (p < 0.001), and the combined osteotomy mean showed minimal change (p = 0.0034). The absolute consistency of the changes and their direction allow suggested guidelines for selection of osteotomy type. There were only slight changes in tibial slope. A significant change in patellar tendon length was seen in seven knees of the opening wedge cohort that had concomitant ACL reconstruction. All had a mean reduction of the Insall-Salvati index of 0.05 (approximately 5%), p = 0.0002. New findings showed higher patellae in female and older patients, unrelated to the surgery.ConclusionsIf it is accepted that patella baja and patella alta should be avoided, then closing wedge osteotomies should be performed only when the patella is low riding, and opening wedge osteotomies should be done only for patients with preexisting patella alta. The combined osteotomy minimizes changes in patellar height. Patellar tendon contractures and tibial slope changes can be avoided. The plateau-patella angle should be measured preoperatively to help decide the type of osteotomy.Level of EvidenceLevel III, therapeutic study. See the Instructions for Authors for a complete description of levels of evidence.

Plateau-patella angle in evaluation of patellar height in osteoarthritis

BackgroundThe plateau-patella angle (PPA), recently introduced as a new and simpler method of measuring patellar height from the lateral radiograph, has the advantage of simplicity over previously described methods as it involves a single angular measurement without the need for calculations. The purpose of this study was to validate the use of the PPA as a measurement for patellar height in knees with moderate to severe osteoarthritis. MethodsA total of 331 patients who underwent total knee arthroplasty at our institution with radiographs prior to surgery were evaluated. Of those, 297 (89.2%) were felt to be adequate for review. Three observers with different levels of orthopedic training measured PPA, Insall–Salvati, Caton–Deschamps, and Blackburne–Peel indices on a subset of 50 consecutive patients. Interobserver agreement for each of the four measurements was calculated and correlation between each of the measurements within each observer was calculated. The measurement of the PPA was repeated. Intraobserver agreement for the PPA was determined and a normal range and distribution was defined for this population. ResultsFor the three observers, the mean PPA for the entire cohort was 25.55, 25.31, and 24.42. The intraclass correlation coefficient (ICC) was 0.81, The ICC and intraobserver assessment were the highest for the PPA compared with the other ratios. The PPA was found to correlate most strongly with the Blackburne–Peel method. ConclusionsThe plateau-patella angle is a reliable way to evaluate patellar height in the osteoarthritic population. The measurement demonstrated a higher interobserver reliability compared with previously described methods. Level of evidenceRetrospective Level IV.

Plateau–Patella Angle in Evaluation of Patellar Height After Total Knee Arthroplasty

The plateau–patella angle (PPA) has been proposed as a new and simpler method to describe patellar height. This method has not been used or validated in knees following total knee arthroplasty (TKA). A modified PPA (mPPA) was developed for use in this population. The method was validated by determining the interobserver and intraobserver reliability of the technique in 50 consecutive patients compared to three well-described methods of describing patellar height after TKA. Three observers then evaluated the mPPA of 297 post-operative radiographs to describe a normal range after TKA for a given technique and implant. The interobserver reliability was the highest for the mPPA compared to the other methods. The mean mPPA for the entire cohort was 21.06, 20.49, and 19.94 for the three observers. The modified plateau–patella angle is a reliable way to evaluate patellar height in patients who have undergone total knee arthroplasty.

Does Medial Patellofemoral Ligament Reconstruction Decrease Patellar Height? A Preliminary Report

The purpose of this study was to evaluate the hypothesis that medial patellofemoral ligament (MPFL) reconstruction for patellar instability decreases patellar height. Preoperative and postoperative lateral knee radiographs of 38 adolescents who underwent MPFL reconstruction between 2005 and 2011 were reviewed. The Insall-Salvati index, Blackburne-Peel index, Caton-Deschamps index, and plateau-patella angle were measured on all radiographs to identify differences in patellar height. These patellar height indices were also measured on lateral knee radiographs of 25 adolescents (control group) who were treated conservatively for osteochondritis dissecans of the knee. The 2 groups were compared to account for patellar height changes secondary to growth and ossification. Intrarater reliability was measured for all patellar height indices at 1-month interval. Preoperatively, patients who underwent MPFL reconstruction had significantly greater patellar height on all indices compared with the control group before and after controlling for age and sex. The patients who underwent MPFL reconstruction showed a significantly greater decrease in patellar height on the Blackburne-Peel or Caton-Deschamps indices over time compared with the control group such that postoperatively there was no difference between groups in these patellar height indices. Furthermore, the change in patellar height indices after MPFL reconstruction did not differ between patients with less than or more than 1-year follow-up. All indices demonstrated good to excellent intrarater reliability. The present study showed a decrease in patellar height in the postoperative period in patients after MPFL reconstruction for patellar instability. Further investigation is necessary to determine the long-term effects of MPFL reconstruction on patellar height. Level III--therapeutic, case series.

Outcomes After Operative Fixation of Complete Articular Patellar Fractures: Assessment of Functional Impairment

Patellar fractures are debilitating injuries that compromise the knee extensor mechanism and are frequently associated with poor outcomes. The purpose of this study was to quantify the functional outcomes of operative treatment of patellar fractures. Functional outcome data on thirty patients with an isolated unilateral patellar fracture were prospectively obtained at three, six, and twelve months postoperatively. All fractures healed. There were two complications (7%) related to the surgery (wound dehiscence and refracture), and eleven patients (37%) underwent removal of symptomatic implants. The tibial plateau-patella angle demonstrated patella baja in seventeen (57%) of the patients. Anterior knee pain during activities of daily living was experienced by twenty-four (80%) of the patients. Clinical improvement occurred over the first six months. However, functional impairment persisted at twelve months, with objective testing demonstrating that the knee extensor mechanism on the injured side had deficits in strength (-41%), power (-47%), and endurance (-34%) as compared with the uninjured side. Despite advances in surgical protocols and acceptable radiographic outcomes, functional impairment remains common after treatment of patellar fractures. Rehabilitation strategies following surgical stabilization of these injuries will be a fruitful area for future clinical research.

The Evaluation of Patellar Height: A Simple Method

Patellar height is evaluated with ratios that have been derived from measurements made on lateral radiographs of the knee. The importance of using a ratio is that magnification, physical size, and flexion angle are eliminated as factors that affect the values. The Insall-Salvati index was the first ratio to be described. It remains the most popular, possibly because normal values are easy to remember. As all of the currently accepted methods are cumbersome to use because they require two measurements as well as a calculation, a single angular measurement was devised (the plateau-patella angle) to offer a simpler alternative. The purpose of this study was to introduce the new method and to assess its validity by comparing it with three classic, commonly used ratios. In two groups of patients, after exclusions, 269 lateral radiographs of the knee were evaluated. All measurements required for the Insall-Salvati, the Blackburne-Peel, and the Caton-Deschamps indices plus the plateau-patella angle were recorded, along with basic demographics. For validation, the new method was compared with the established methods, and interobserver and intraobserver reliability were computed. There was excellent correlation between the proposed angle and the three selected indices, especially with the Blackburne-Peel index. Interobserver and intraobserver reliability was high and compared favorably with that reported in the literature for the three classic ratios. The calculated ratios were in line with those described in the literature. The mean plateau-patella angle was 25°. Ninety percent of the measurements fell between 20° and 30°, and one standard deviation above and below was 21° to 29°. The plateau-patella angle, a new method of evaluating patellar height, can be measured rapidly with use of either a goniometer or digital software. Its range is easy to remember, it is reliably reproduced, and it correlates well with traditional methods. It is thus a valid and easy alternative method for the evaluation of patellar height.