Patellar Tracking Research Articles

The Orientation of the Prosthetic Trochlear Angle Is Predictable in Kinematically Aligned Total Knee Arthroplasty

Abstract: Objective: This study aimed to predict the orientation of the prosthetic trochlear angle (PTA) relative to the quadriceps line of force (QLF) in kinematically aligned total knee arthroplasty (KA-TKA) by using preoperative radiographic parameters. Methods: This study included 144 patients who underwent KA-TKA with a femoral component designed for mechanical alignment (MADFC), with a PTA of 6°. Radiographic parameters, including the lateral distal femoral angle (LDFA) and the QLF^FMA (quadriceps line of force–femoral mechanical axis angle), were measured pre- and postoperatively. We developed and validated a formula to predict PTA orientation based on these values: “X = QLF^FMA−(PTA−(90°−LDFA))”, where values of x > 0° predict a lateral PTA orientation, while x < 0° predicts a medial PTA. Results: The formula accurately predicted PTA orientation in 100% of the cases, with a difference between the predicted and actual PTA values of <0.5° in 75% of the cases. Patients with an LDFA < 86° and lower QLF^FMA values were identified as at risk for medial PTA orientation, which can affect patellar tracking. Conclusions: Our formula offers a reliable preoperative tool for predicting PTA orientation in KA-TKA, aiding in component selection and alignment strategies to improve patellofemoral function and patient outcomes.

Patients with jumping sign exhibit rotational and bony structural abnormalities consistent with high-grade J-sign in recurrent patellar dislocation.

To propose a new sign of patellar maltracking in recurrent patellar dislocation (RPD) and compare the differences in lower limb rotational and bony structural abnormalities among the different signs. A retrospective study included 279 patients (mean age: 22 years; female: 81%) who underwent primary surgery for RPD over the past 4 years was performed. The patients were grouped based on the characteristics of patellar tracking: low-, moderate- and high-grade J-sign. Patients were further divided into 'jumping' and 'gliding' subgroups based on whether the patella exhibited a 'jumping' sign during flexion-extension motion. All patients received bilateral standard hip-knee-ankle CT scans. The rotational and bony structural parameters of affected knees were measured, and the differences in these variables among the groups were described and analyzed. Reliability analysis was performed to test the consistency of J-sign grading and measurements. There were 92, 100 and 87 patients in the low-, moderate- and high-grade J-sign, respectively. The overall incidence of the jumping sign is 37%. The incidence of the 'Jumping sign' in the high-grade J-sign was significantly higher than in the other two groups (82% vs. 32% vs. 0, p < 0.001). Compared to those with the gliding sign, patients with the jumping sign have higher proportions of increased femoral anteversion (40.8% vs. 24.4%, p = 0.004), excessive knee torsion (61.2% vs. 15.3%, p < 0.001), trochlear dysplasia (95.1% vs. 69.3%, p < 0.001), pronounced supratrochlear spur (73.1% vs. 32.3%, p < 0.001), increased tibial tuberosity-trochlear groove distance (68% vs. 43.3%, p < 0.001), flatter lateral trochlear inclination (81.3% vs. 27.5%, p < 0.001) and excessive sulcus angle (68.7% vs. 35.3%, p = 0.003). No significant morphological differences were found in various bony structural parameters between knees with jumping sign and high-grade J-sign (all p > 0.05). The inter-observer reliability kappa values were 0.65 for the quadrant classification and 0.83 for the new patellar sign. In RPD patients, the rotational and bony structural abnormalities in the jumping sign are highly consistent with the high-grade J sign. This finding may assist the surgeon and their patients in making informed decisions about further imaging tests and osteotomy procedures in the treatment of RPD. Level IV, cross-sectional study.

Intraoperative Patellofemoral Kinematic Acquisition: The Design, Testing, and Validation of a Setup for Clinical Studies.

Background/Objectives: Abnormalities in patellar tracking, often overlooked in surgical planning, have been identified as a contributing factor to total knee arthroplasty (TKA) complications, including anterior knee pain, patellar subluxation, and dislocation. This study aims to evaluate the repeatability of a novel intraoperative setup for assessing patellofemoral kinematics and its interaction with prosthesis design and positioning during surgery. This setup may support personalized alignment techniques in TKA, potentially improving surgical outcomes. Methods: Kinematic data were collected under both native and post-TKA conditions, and the Repeatability Coefficient (RC), Intraclass Correlation Coefficient (ICC), and Limits of Agreement of the Mean were calculated to assess measurement reliability. Results: RC values indicated high repeatability, with patellar flexion averaging an RC of 1°. Rotation and tilt demonstrated an RC below 1° post-mid-flexion, while patellar shift maintained an RC of approximately 1.6 mm. ICC and the extended Bland and Altman analysis showed an excellent agreement (ICC > 0.9) and an expected mean difference of zero for all the measured parameters. Measurements were consistent across both flexion and extension, and between native and post-TKA conditions. Conclusions: The proposed setup for intraoperative patellofemoral kinematic assessment demonstrated high repeatability and practical utility. The approach was found to be non-intrusive to patellar motion tracking and can be robustly integrated into the intraoperative workflow. This method provides a reliable approach for real-time patellar tracking, which may contribute to more personalized and precise TKA procedures, potentially reducing post-surgical dissatisfaction and complications.

Mid-term Outcomes of Patella Resurfacing During Total Knee Arthroplasty (TKA): Clinical, Functional, and Radiographic Insights.

Aim The primary objective of the study was to evaluate the mid-term implant survivability, rate of revisions, and clinical and functional outcomes following patella resurfacing during total knee arthroplasty (TKA) utilizing posterior stabilized (PS) total knee system (TKS). Methods A prospective, single-arm, multi-center, post-marketing surveillance encompassed patients with end-stage primary knee osteoarthritis (OA) or inflammatory arthritis. The time points of the study included baseline, six weeks, six months, one year, and three years post-operatively. Clinical outcomes included Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, Short Form-36 questionnaire (SF-36), and Knee Society Score (KSS) for quality of life (QoL). Radiographs assessed loosening, patella tracking, and implant longevity. Functional outcomes were assessed by range of motion (ROM). Result The study included 74 patients undergoing patella resurfacing during TKA with a PS all-poly component TKS at 10 centers in India. Among the study population, 85% were female, and the average age of the population was 65.13±7.20 years. End-stage OA (70 patients) and inflammatory arthritis (four patients) were the prevalent conditions. Patella sizes used were: 25 mm (n=1), 28 mm (n=29), 31 mm (n=40), and 34 mm (n=4). Primary outcomes showed implant survival was 100% with no revisions after three years. Local soft tissue infections and discomfort affected 3.2%, with no additional adverse events. Radiographs showed well-implanted patellar components with no misalignment or wear after three years. Secondary outcomes showed a significant three-year increase in mean ROM from 85.50°±15.02° to 122.45°±2.44°. After three years, clinical and functional KSS improved to 90.36±3.72 (baseline: 21.11±14.49) p<0.001 and 97.95±3.67 (baseline: 27.16±13.22) p<0.001, respectively. WOMAC values for pain, stiffness, and difficulty decreased significantly (p<0.001) over the three-year duration. SF-36 evaluating QoL showed substantial improvements (physical functioning, role limitation, and general health). Conclusion The study highlights the success of patella resurfacing during TKA, demonstrating excellent implant survival, improved functional outcomes, and QoL over a three-year period.

Three-dimensional automated measurements of femoral angles for the preoperative planning in dogs with patellar luxation.

To report the surgical outcomes of treating patellar luxation (PL) in dogs with surgical planning based on three-dimensional (3D) automated measurement of femoral angles. Multicenter retrospective study. Forty-one dogs with PL underwent preoperative computed tomography (CT). Three-dimensional femur models were exported as stereolithographic files, and imported into computer-aided design (CAD) software where 3D measurements were performed. The anatomical laterodistal femoral (aLDFA), femoral neck (FNA), and femoral torsion (FTA) angles were recorded. Surgical records, complications, radiographic femoral postoperative alignment, preoperative and postoperative lameness evaluation, and patellar position were reviewed. The success of the surgical outcome was based on the presence of normal patellar tracking at the last clinical recheck. Forty-seven limbs were included; 46% of the cases (22/47) were affected by grade 3 PL. Mean (±SD) 3D aLDFA, FNA, and FTA measurements were 101.4° (±3.6), 132.5° (±2.6), and 17.6° (±4.3) in dogs with medial patellar luxation (MPL) and 89.3° (±7.6), 134.8° (±2.9), 36.9° (±5.3) with lateral patellar luxation (LPL), respectively. Based on the 3D preoperative planning, corrective osteotomies were performed in 34 of 47 cases. The mean radiographic follow-up was 4.7 months. At the final follow-up, PL was successfully treated in 45 of 47 cases. Patella reluxated in five cases. In three of five cases, the 3D automated plan was not followed by the surgeon. Surgical treatment of PL based on 3D femoral measurements successfully corrected PL in 45 of 47 cases (96%). This is the first study reporting the use of 3D automated femoral angle measurement in clinical cases affected by PL.

Optimizing the patellofemoral compartment in total knee arthroplasty: Is it time for dynamic assessment?

Despite improvements in implant design, surgical techniques and assistive technologies for total knee arthroplasty (TKA), anterior knee pain (AKP) remains frequently reported, even by satisfied patients. This persistent problem calls for better understanding and management of the patellofemoral or anterior compartment during surgery, just as the techniques and strategies deployed to optimize the flexion and extension spaces through personalized alignment, bone cuts and ligament balancing. Assistive technologies such as navigation and robotics provide new tools to manage this 'third space' through precise pre-operative planning and dynamic intra-operative assessment. Such endeavors must start with clear definitions of the 'third space', how it should be measured, what constitutes its 'safe zone', and how it affects outcomes. There are yet no established methods to evaluate the patellofemoral compartment, and no clear thresholds to define over- or under-stuffing. Static assessment using lateral radiographs provides a limited understanding and depends considerably on flexion angle, while dynamic evaluation at multiple flexion angles or using intra-operative computer or robotic-assistance enables a broader perspective and solutions to manage patellar tracking and anterior offset. Future studies should investigate the impact of variations in anterior offset in TKA, define its safe zone, and understand the effects of of thresholds for over- or under-stuffing. Experimental methods such as in-vivo motion analysis and force sensors could elucidate the influence of anterior offset on flexion and extension biomechanics.

Double-Level Torsional Osteotomy in Severe Torsional Malalignment: A Surgical Technique

Background: Torsional malalignment of the femur and/or tibia is associated with patellar maltracking, and torsional osteotomies have shown to improve clinical symptoms. In patients with severe torsional malalignment, a double-level torsional osteotomy may be necessary. Indications: Symptomatic torsional malalignment leading to patellofemoral maltracking associated with anterior knee pain and/or patellofemoral instability. Technique Description: A double-level torsional osteotomy correcting both increased internal femoral torsion and increased external tibial torsion, is described. Meticulous preoperative deformity analysis and planning of the osteotomy is mandatory. An arthroscopy of the knee is performed first to evaluate the patellofemoral joint and patellar tracking. Tibial torsional correction is performed by a lateral approach. A biplanar osteotomy is performed, and the amount of torsional correction is controlled by 2 Schanz screws. Osteosynthesis can be done via a bended 5-hole DC-Plate or an angle-stable plate. The femoral osteotomy is performed by a medial approach. A uniplanar osteotomy is performed perpendicular to the mechanical axis of the femur. The amount of torsional correction is controlled by 2 Schanz screws. Osteosynthesis is achieved by an angle-stable plate. Results: Double-level torsional osteotomy has been shown to be an effective treatment for patients with patellar dislocation or subluxation associated with severe torsional malalignment. In a series of 18 patients, double-level osteotomy led to improved patellofemoral stability, decreased pain, and increases subjective outcome scores. Discussion/Conclusion: In patients with patellofemoral problems caused by a combined increased tibial external torsion and increased femoral internal torsion, a double-level torsional osteotomy is able to correct torsional angles to normal. Available clinical data on this procedure are promising. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Internal rotational patellar resection and patella alta induced patellar maltracking in total knee arthroplasty: intraoperative measurement of the patellofemoral pressure

BackgroundAnterior knee pain due to patellar maltracking following total knee arthroplasty (TKA) reduces patients’ satisfaction. This study aimed to determine the patellofemoral pressure (PFP) in patients with favorable patellar tracking (FT) and impaired patellar tracking (IT) following TKA, the factors causing patellar maltracking, and the effect of lateral retinacular release (LRR) on patients with IT.MethodsForty-four patients with varus knee osteoarthritis undergoing cruciate-retaining TKA were enrolled. After component implantation, patients with a separation of ≥ 2 mm of the patellar medial facet from the medial femoral trochlea throughout knee range of motion were classified into the IT group; meanwhile, the others were classified into the FT group. PFP was measured intraoperatively in three phases: (1) with the resurfaced patella (RP); (2) with the resurfaced patella and knee (RPK); and (3) when LRR was performed in IT (post-LRR). The PFPs at 0°, 90°, 120°, and 135° knee flexion were compared between FT and IT using the Mann–Whitney U test. Pairwise comparison of the PFP in IT between RPK and post-LRR was performed using the Wilcoxon signed-rank test. Correlations between PFP and pre- and postoperative radiographic parameters, such as hip–knee–ankle angle, lateral distal femoral angle, medial proximal tibial angle, anterior femoral offset, Insall–Salvati ratio (ISR), patellar tilt, and patellar resection angle (PRA), were evaluated using Spearman’s rank correlation coefficients.ResultsHigh lateral PFP in the knee flexion position led to patellar maltracking. Patients with IT (n = 24) had higher lateral and lower medial PFP than did patients with FT (n = 20) at 90°, 120°, and 135° knee flexion in RP and RPK. LRR in IT reduced the lateral PFP in the knee flexion position. PRA and ISR were correlated with the lateral PFP at no less than 90° in RP and RPK.ConclusionsThis study demonstrated that internal rotational patellar resection, which resulted in a thick medial patellar remnant and a thin lateral counterpart, and patella alta were the causative factors of high lateral PFP, which induced patellar maltracking after TKA. Surgeons should avoid internal rotational patellar resection to achieve FT and perform LRR in patients with patellar maltracking.

Poster 249: Distal Femoral Coronal Realignment Osteotomies Alter CT-Measured Tibial Tuberosity to Trochlear Groove (TT-TG) Distance in Addition to Mechanical Axis Deviation – A Cadaveric Study

Objectives: Patellar tracking has been shown to be affected by limb alignment. Many patients with underlying valgus deformity with patellar instability have elevated tibial tuberosity–trochlear groove (TT-TG) measurements. Correction of limb alignment improves Q-angle, however, its effect on TT-TG as measured by computed tomography (CT) has yet to be demonstrated. We hypothesize that changing the limb alignment as measured by mechanical axis deviation (MAD) through a distal femoral osteotomy (DFO) would also cause a change in TT-TG distance as measured by CT. Methods: Lateral distal femoral osteotomies were performed on 5 cadaveric specimens (10 limbs) and fixed with an external fixator. The native MAD and baseline TT-TG were measured using a CT scanogram. Subsequent scans were then performed altering the MAD using calibrated radiolucent wedges in 5 mm increments (0-25 mm) on a single side, using the contralateral limb as the control. Repeat measurements of MAD and TT-TG were obtained, and once completed, original alignment was restored, and the contralateral limb was taken through the same protocol with the opposite limb serving as the control. Measurements were performed by two independent observers and averages obtained. Linear regression models were created, and statistical analysis of variance was performed. Results: A CT-scanogram that measured TT-TG distances were significantly altered by changes in limb alignment. According to our linear regression model, each 1° of MAD alteration resulted in TT-TG change of approximately 0.4 mm. With every 5° change in limb alignment, the TT-TG changed by approximately 2 mm (Figure 1). Altering MAD from 6° valgus to 7° varus decreased the TT-TG mean from 14.3 mm to 7.7 mm, p &lt; 0.05. Conclusions: Changes in coronal limb alignment through a distal femoral corrective osteotomy produce significant changes in TT-TG in addition to correcting MAD in a cadaveric model. These findings should be considered when determining appropriate corrective procedures for patients with valgus alignment and patellar instability. [Figure: see text]

Kinematical alignment better restores native patellar tracking pattern than mechanical alignment.

The purpose of this study was to assess whether kinematic alignment (KA) outperforms mechanical alignment (MA) in restoring patellar tracking to native patterns by using a clustering algorithm. Twenty cadavers (40 knees) were evaluated. For each cadaver, one knee was randomly assigned to KA and the other to MA. KA total knee arthroplasty (TKA) procedures were performed using a caliper-verified technique, while MA TKA procedures utilized a measured resection technique. Subsequently, all specimens were mounted on a customized knee-testing system, and patellar tracking was measured using a motion analysis system. All patellar tracking data were clustered using the density-based spatial clustering of applications with noise algorithm. Differences in patellar tracking patterns and the restoration of native patellar tracking were compared between the two alignment strategies. Patellar tracking patterns following KA were considerably different from MA. Pre- and post-TKA patellar tracking patterns following MA were grouped into separate clusters, whereas a substantial proportion of patellar tracking patterns following KA were grouped into the pre-TKA dominant cluster. Compared to MA, a greater proportion of patellar tracking patterns following KA showed similar patterns to native knees (p < 0.05) and more patellar tracking patterns following KA paired with preoperative patterns (p < 0.01). KA restored native patellar tracking patterns more closely compared to MA. Level I, therapeutic study.

Robotic assessment of patella tracking in total knee arthroplasty

Robotic tools have been developed to improve planning, accuracy and outcomes in total knee arthroplasty (TKA). The purpose of this study was to describe and illustrate a novel technique for assessing the patellofemoral (PFJ) in TKA using an imageless robotic platform. A consecutive series of 30 R-TKA was undertaken by a single surgeon utilising the described technique. A technique to dynamically assess the PFJ intra-operatively, pre- and post-implantation was developed. A full set of data from 9 cases was then collected and reviewed for analysis. A series of dynamic PFJ tracks collected intra-operatively pre- and post-implantation are presented. Furthermore, a full assessment of PFJ over and under-stuffing through a 90° arc of flexion is illustrated. Finally, a pre- and post-centre of rotation for the PFJ was defined and measured. The described technique was defined over a series of 30 R-TKA using the described robotic platform. Nine cases were analysed to determine what data could be measured using the robotic platform. Intra-operative real-time data allowed a visual assessment of PFJ tracking through a range of motion of 0°-90° flexion pre- and post-implantation. PFJ over and under-stuffing was also assessed intra-operatively through a range of motion of 0°-90° flexion. Post-operative analysis allowed a more detailed study to be performed, including defining a pre- and post-implantation centre of rotation (COR) for the patella. Defining the COR allowed the definition of a patella plane. Furthermore, patella mediolateral shift in full extension, and end flexion could be measured. Intra-operative assessment of the PFJ in TKA is challenging. Robotic tools have been developed to improve measurement, accuracy of delivery and outcomes in TKA. These tools can be adapted in novel ways to assess the PFJ, which may lead to further refinements in TKA techniques.

Assessment of average femoral component rotation for balancing functionally aligned total knee replacement in varus deformity: Robotic image guidance study

Ensuring proper femoral component alignment post-Total Knee Arthroplasty (TKA) is crucial for normal patellofemoral (PF) kinematics. However, the customary 3° external rotation relative to the Posterior Condylar Axis (PC Axis) may not universally apply, and the expected final femoral component rotation remains unclear in functionally aligned knees. This study examines the relation between the Transepicondylar Axis (TEA) and PC axis, known as Posterior Condylar Angle (PCA) in Indian patients along with factors influencing PCA, and the feasibility of reproducing patient-specific PCA using image-guided Cuvis joint robot. Forty patients (52 Knees) with primary osteoarthritis and varus deformity were prospectively evaluated. Native PCA was determined using CT-based J planner. Pre-operative patellar shape, PF tilt, PF shift, final femoral component rotation (representing post-operative PCA), final patellar tracking, and post-operative functional and radiological assessment at 3 months were recorded. Study participants averaged 64.3 years of age, with a female-to-male ratio of 23 to 17. Varus deformities varied, with IA2 being most prevalent, and sagittal plane deformities included fixed flexion (34.6%) and hyperextension (44.2%). The average PCA was 1.9° (range: 0°-7.3°), with most knees (41 out of 52) below 3°. The majority had Wiberg type 1 patellae, with pre-operative patellar tilt averaging 5.63°, reducing post-operatively to 4.43°. Most patients (37 out of 40) achieved excellent Knee Society functional scores at the 3-month mark. Complications included one case of delayed wound healing and one femoral array pin breakage. Notably, our study revealed a significant deviation in PCA from the commonly reported 3° in Western literature, underscoring the need for region-specific considerations in TKA planning. PCA of our population is statistically different from customary 3° followed with jig system. Image guided Robotics helps to identify patients specific PCA and reproducing the same was more commonly possible in patients with reducible Varus deformity.

Trochlea Dysplasia as the Major Anatomic Risk Factors for Patellofemoral Joint Instability: An Infographic as a Visual Learning Tool.

Patellofemoral instability (PFI) is a common condition in children and adolescents, ranging from mild discomfort and mal-tracking to lateral patellar dislocation [1]. A number of anatomical risk factors have been described in the literature, such as trochlear dysplasia, patella alta, excessive tibial tuberosity to trochlear groove (TT-TG) distance, patellar tilt and soft tissue alterations [2]. Among them, TD has been identified as the main anatomical risk factor with the strongest association with PFI [1, 2]. In the study by Dejour et al. [2] radiographically observed TD was identified in 96% of patients with a history of patellofemoral dislocation [1, 2]. Patients with Dejour Type D dysplasia are characterized by a prominent and convex lateral facet with a vertical connection to a hypoplastic medial facet (Figure 1), which provides inadequate tracking of the patella in the trochlea during flexion leading to patella subluxation [2]. Non-operative treatment of lateral patellar dislocation presents a rate of re-dislocation up to 70% within 24 months of the first episode [3]. Sulcus deepening trochleoplasty is indicated for Type B and D dysplasia, in order to improve patella tracking, reduce the rate of re-dislocation and achieve good functional outcomes [2, 4]. Trochlea dysplasia is defined as a shallow or flattened groove with decreased resistance to lateral patellar translation. TD can be assessed on computed tomography (CT) and magnetic resonance imaging (MRI) with the use of overlapping axial images and are able to show perfectly the global shape of the femoral trochlea [2]. The thresholds for identifying trochlear dysplasia are established based on the sulcus angle ≥ 145°, medial/lateral trochlea facet asymmetry < 40%, trochlear depth < 3 mm and lateral trochlear inclination ≤ 11° and therefore it can be used in young adolescents [4, 5]. A deep knowledge of anatomic variations and abnormalities of the patellofemoral joint, which may predispose to PFI, is crucial in order to choose the appropriate treatment for each patient.

A Sensorized 3D-Printed Knee Test Rig for Preliminary Experimental Validation of Patellar Tracking and Contact Simulation.

Experimental validation of computational simulations is important because it provides empirical evidence to verify the accuracy and reliability of the simulated results. This validation ensures that the simulation accurately represents real-world phenomena, increasing confidence in the model's predictive capabilities and its applicability to practical scenarios. The use of musculoskeletal models in orthopedic surgery allows for objective prediction of postoperative function and optimization of results for each patient. To ensure that simulations are trustworthy and can be used for predictive purposes, comparing simulation results with experimental data is crucial. Although progress has been made in obtaining 3D bone geometry and estimating contact forces, validation of these predictions has been limited due to the lack of direct in vivo measurements and the economic and ethical constraints associated with available alternatives. In this study, an existing commercial surgical training station was transformed into a sensorized test bench to replicate a knee subject to a total knee replacement. The original knee inserts of the training station were replaced with personalized 3D-printed bones incorporating their corresponding implants, and multiple sensors with their respective supports were added. The recorded movement of the patella was used in combination with the forces recorded by the pressure sensor and the load cells, to validate the results obtained from the simulation, which was performed by means of a multibody dynamics formulation implemented in a custom-developed library. The utilization of 3D-printed models and sensors facilitated cost-effective and replicable experimental validation of computational simulations, thereby advancing orthopedic surgery while circumventing ethical concerns.

The effect of high-intensity laser therapy on pain and lower extremity function in patellofemoral pain syndrome: a single-blind randomized controlled trial

Patellofemoral pain syndrome (PFPS) is a set of symptoms that negatively affect the daily life activities of the individual, leading to functional disability and significant loss of labor, especially in young adults. PFPS is usually due to weakness of the vastus medialis obliquus (VMO) resulting in abnormal patellar tracking and pain. Our study aims to compare the efficacy of high-intensity laser therapy (HILT) on pain and lower extremity function in the treatment of PFPS with different electrophysical agents (EPAs). The study was designed as a single-blind randomized controlled trial. Forty-five people with PFPS (aged 25–45 years) were included in the study. The patients were randomly divided into three groups and a total of ten sessions of treatment were administered to all three groups for 2 weeks, 5 days a week. High-intensity laser (HILT) and exercise program were applied to group 1. Ultrasound (US), transcutaneous electrical nerve stimulation (TENS), and exercise program were applied to group 2. In group 3, US, interferential current (IFC), and exercise program were applied. Both groups underwent three evaluations: pre-treatment, post-treatment, and 12 weeks after treatment. Outcome measures included the visual analog scale for pain severity (VAS), knee flexion range of motion (FROM), Q angle, pain threshold, muscle strength of quadriceps and hamstring, Kujala patellofemoral scoring, lower extremity functional scale (LEFS), and Timed Up and Go Test (TUG). The ANOVA was used for comparing the data of the groups, and two-way repeated measure ANOVA was used to compare at the pre-post and post-intervention 3rd month. The LSD and Bonferroni post hoc tests were also used to identify the between-group differences. Groups 2 and 3 were statistically effective in pain and functionality (p < 0.05). Group 1 was found to be statistically more effective than other groups in reducing pain (95% confidence interval (CI), 0.000/0.000; p = 0.000), increasing knee flexion angle (95% CI, 127.524/135.809; p = 0.000), and increasing lower extremity function (95% CI, 75.970/79.362; p = 0.000). This study indicated that high-intensity laser therapy was found to be a more effective method in the treatment of patellofemoral pain syndrome after 3 months of follow-up compared to US-TENS combination and US-interferential current combination treatments. Also, HILT can be used as an effective method in combination with an appropriate exercise program including vastus medialis strengthening to reduce pain and increase functionality in the patients with PFPS.

Prevalence of Anterior Knee Pain and Its Associated Risk Factors in Professional Badminton Players

Background :Badminton is a sport which need repetitive lunging, squatting and running which causes Patella to move on femur and causing posterior compressive force and causing anterior knee pain .The patellofemoral joint can undergo very high stresses during typical activities .The patellofemoral joint reaction (contact) force is influenced by both the quadriceps force and the knee angle. As the knee flexes and extends, the patella is pulled by the quadriceps tendon superiorly and simultaneously by the patella tendon inferiorly. The combination of these pulls produces a posterior compressive force of the patella on the femur and cause anterior pain Methods :We performed a study with the help of google form, cluster sampling is done. The prevalence of anterior knee pain is studied with kujala questionnaire and ,its associated risk factors are being noted Results :In this study 50 players participated in that 31 are male and 19 are female. 32 players complains of anterior knee pain in that 23 players complains on single knee pain and 8 players complain of both knee pain .increased in number of hours of practice and and years of training can cause in over use injury of anterior knee and pain. With the help of Kuajal questionnaire players are being assessed and condition of knee is being determined. Associated risk factors are also being noted in the players in that 8% players were identified with genu valgum,4% with abnormal patellar tracking patelar ,2%foot misalignment Conclusion :Anterior knee pain is a prevalent issue among badminton players, influenced by various intrinsic and extrinsic factors. Understanding the prevalence and associated risk factors of anterior knee pain in this population is critical for developing targeted prevention strategies and optimizing athlete health and performance. Future research should continue to investigate the complex interplay of biomechanical, training-related, and environmental factors contributing to anterior knee pain in badminton players, with the ultimate goal of reducing injury burden and enhancing athlete well being

Three-Dimensional Imaging of the Patellofemoral Joint Improves Understanding of Trochlear Anatomy and Pathology and Planning of Realignment

Three-dimensional (3D) modeling using digital or printed models provides a unique perspective that caters to cognitive spatial ability in a way that can add to our understanding and mental representations of human anatomy. This is particularly useful in the setting of trochlear dysplasia, where the morphology of the groove can exhibit substantial variability and complexity. Using 3D reformatted images and models, a pragmatic understanding of how morphology influences patellofemoral pathology can be gleaned. Further, this perspective facilitates cognition of what patellar tracking may look like after realignment procedures. Using 3D modeling, concepts such as patella alta, trochlear depth, lateralization of the patellar entry point, trochlear curvature, and the presence of a proximal trochlear spur can help afford a better understanding of how trochlear anatomy may influence tracking while also providing insight as to the ideal tracking path. The use of 3D has recently emerged as a useful tool in multiple surgical subspecialties, particularly in situations involving surgical planning or complex anatomy. Given the complexity and variation in trochlear morphology in patients with trochlear dysplasia who develop either patellar instability or focal overloading, 3D modeling is well-suited to provide a perspective that can add to our understanding of trochlear dysplasia, and potentially even how we diagnose and treat it. LEVEL OF EVIDENCE: Level V, expert opinion.

Use of patellofemoral digital twins for patellar tracking and treatment prediction: comparison of 3D models and contact detection algorithms.

Introduction: Poor patellar tracking can result in painful contact pressures, patella subluxation, or dislocation. The use of musculoskeletal models and simulations in orthopedic surgeries allows for objective predictions of post-treatment function, empowering clinicians to explore diverse treatment options for patients. Although a promising approach for managing knee surgeries, the high computational cost of the Finite Element Method hampers its clinical usability. In anticipation of minimal elastic deformations in the involved bodies, the exploration of the Multibody Dynamics approach emerged as a viable solution, providing a computationally efficient methodology to address clinical concerns related to the knee joint. Methods: This work, with a focus on high-performance computing, achieved the simulation of the patellofemoral joint through rigid-body multibody dynamics formulations. A comparison was made between two collision detection algorithms employed in the simulation of contact between the patellar and femoral implants: a generic mesh-to-mesh collision detection algorithm, which identifies potential collisions between bodies by checking for proximity or overlap between their discretized mesh surface elements, and an analytical contact algorithm, which uses a mathematical model to provide closed-form solutions for specific contact problems, but cannot handle arbitrary geometries. In addition, different digital twins (3D model geometries) of the femoral implant were compared. Results: Computational efficiency was considered, and histories of position, orientation, and contact force of the patella during the motion were compared with experimental measurements obtained from a sensorized 3D-printed test bench under pathological and treatment scenarios. The best results were achieved through a purely analytical contact detection algorithm, allowing for clinical usability and optimization of clinical outcomes.

Patellar tilt, congruence angle, and tibial tubercle-trochlear groove distance are correlated with positive J-sign in adolescents

ABSTRACT Purpose The J-sign is a clinical evaluation tool that assesses for patellar maltracking and is considered positive if lateral translation of the patella in extension, in the pattern of an inverted J is observed. This study aims to determine the association of clinical J-sign with imaging features noted on dynamic kinematic computed tomography (DKCT). Methods A retrospective review was conducted by reviewing the clinical records of all patients aged 18 years or younger who had a CT patellar tracking scan done between 1 January 2005 to 31 December 2016 in a single institution. Patients who had the presence or absence of a ‘J-sign’ evaluated clinically were included. Radiographic parameters evaluated using the axial cuts include the patellar tilt angle, congruence angle, Dejour’s classification, femoral sulcus angle, trochlear groove depth, and Wiberg’s classification. Patients were then divided into two groups based on the presence or absence of J-sign on clinical examination. The radiographic measurements were then analyzed for association with the presence or absence of J-sign on clinical examination. Results Patients with a positive J-sign had an increased patellar tilt of 23.3° ± 14.2° and an increased congruence angle of 47.1° ± 28.5° when measured in extension as compared to a patellar tilt of 18.3° ± 10.8° and a congruence angle of 32.1° ± 20.8° in patients with a negative J-sign (p = 0.024 and 0.004, respectively). Comparisons of the change in congruence angles with the knee in full extension and at 20° flexion also yielded significantly higher change of 28.0° ± 20.4° in patients with a positive J-sign as compared to 11.9° ± 17.5° in patients with a negative J-sign. Patients with a positive J-sign also had an increased TT-TG distance of 17.6 ± 5.6 mm as compared to a TT-TG distance of 14.7 ± 6.9 mm in patients with a negative J-sign (p = 0.01). Conclusion Patients with a positive J-sign had an increased patellar tilt and an increased congruence angle when measured in extension. Increased TT-TG distance was also significantly associated with positive J-sign. Patients with a positive J-sign also had a greater change in their congruence angle when measured with the knee in full extension and at 20° of flexion.

Robot-Assisted Patellofemoral Arthroplasty.

Patellofemoral arthroplasty is indicated in patients with isolated patellofemoral arthritis in whom nonoperative treatment has failed2. The goal of the presently described procedure is to provide relief from patellofemoral arthritis pain while maintaining native knee kinematics2. Patient radiographs are carefully reviewed for isolated patellofemoral arthritis in order to determine the appropriateness of robotic-assisted patellofemoral arthroplasty. Magnetic resonance imaging can be performed preoperatively to help confirm isolated patellofemoral arthritis. We perform this procedure with use of the MAKO Surgical Robot (Stryker). Preoperative computed tomography is performed to plan the bone resection, the size of the implant, and the positioning of the device. The steps of the procedure include (1) medial parapatellar arthrotomy, (2) intraoperative inspection to confirm isolated patellofemoral arthritis, (3) patellar resurfacing, (4) placement of optical arrays and trochlear registration, (5) trochlear resection, (6) trialing of implants, (7) removal of the optical array, (8) impaction of final implants, (9) confirmation of appropriate patellar tracking, and (10) closure. Alternatives to patellofemoral arthroplasty include standard nonoperative treatment, bicompartmental arthroplasty, total knee arthroplasty, tibial tubercle osteotomy, partial lateral facetectomy, and arthroscopy2. Patellofemoral arthroplasty is indicated in patients with isolated patellofemoral arthritis in whom nonoperative treatment has failed2. Patellofemoral arthroplasty may be superior to total knee arthroplasty because it helps treat pain that affects patient quality of life and activities of daily living while also preserving greater tibiofemoral bone stock2. We recommend against performing patellofemoral arthroplasty in patients with arthritis of the tibiofemoral joints2. In properly selected patients, outcomes include improvement in patient pain and function1. One study found that robotic-assisted patellofemoral arthroplasty may result in improved patellar tracking compared with non-robotic-assisted patellofemoral arthroplasty1; however, functional outcomes were found to be similar between procedures, and data for all non-robotic-assisted controls were retrospectively captured1. Confirm isolated patellofemoral arthritis on radiographs and/or magnetic resonance imaging.Review the preoperative plan for appropriate positioning of the trochlear implant.○ Confirm coverage of the trochlear groove.○ Avoid medial overhang.○ Avoid lateral overhang.○ Avoid anterior femoral notching.○ Avoid impingement of the trochlear component into the notch.○ Avoid excessive prominence of the trochlear component on the anterior femoral cortex.○ General principles are to place the trochlear component in 0° to 6° of flexion and 0° to 2° of external rotation.Robotic-assisted trochlear resurfacing is accurate and efficient. CT = computed tomography.