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Lateral patellar tilting can also result in cartilage lesions of tibial plateau - the characteristic features of excessive lateral pressure syndrome: a retrospective study of 141 cases

BMC Musculoskeletal Disorders volume 26, Article number: 443 (2025) Cite this article

Abstract

Background

To comprehensively summarize the characteristics of cartilage and other knee joint lesions associated with excessive lateral pressure syndrome (ELPS).

Methods

Patients diagnosed with ELPS and admitted to our department between October 1, 2015, and September 30, 2023 were retrospectively included in this study. Prior to undergoing arthroscopic examination and surgery, all included patients underwent knee MRI evaluation. The lesion regions and corresponding lesion grading of each knee joint were meticulously documented, and the concordance between imaging and arthroscopic evaluation was quantified. All patients were categorized based on age and gender, and further comparison of each group was made.

Results

There were 82 male participants and 59 female participants included. No significant differences in age or side distribution were observed. Regarding gender comparison, there were no statistically significant differences in imaging observations (P = 0.940) and arthroscopic examinations (P = 0.237). There were no significant differences observed in radiographic incidences among all three groups divided by age, while during arthroscopic examination, a significantly higher incidence was found in over 50 group compared to both those under 20 and those aged between 20 and 50. The incidence of Graded that both radiographic evaluation and arthroscopic observation demonstrated a significantly higher incidence in the > 50 years old group compared to the other two groups.

Conclusions

In addition to patellofemoral joint cartilage lesions, excessive lateral pressure syndrome (ELPS) of the patella can also cause cartilage lesions in the central region of the medial tibial plateau and posterior region of the lateral tibial plateau. These specific sites of lesion are not influenced by gender or age. The incidence of full-thickness cartilage defects gradually increases with age.

Trial registration

The Ethics Committee of the Third Hospital of Peking University approved this study. (No.: IRB00006761-M2021002)

Level of evidence

IV Case series.

Peer Review reports

Background

The patellofemoral pain syndrome (PFPS) accounts for 25 to 40% of all knee disorders [1,2,3], and the excessive lateral pressure syndrome (ELPS) of the patella is the main cause of PFPS. This condition is characterized by a tightened lateral retinaculum and an excessive lateral tilting of the patella, resulting in reduced medial patellar mobility and abnormally high pressure on the lateral facet of the patella and the lateral trochlea of the femur [2]. The lateral retinaculum serves as the primary static stabilizer during early flexion(0°-30°) before engaging with the trochlea, and a tightened or thickened lateral retinaculum would lead to excessive lateral tilting of the patella [4]. Patients with ELPS commonly present with diffuse anterior knee pain in early stages, which progresses to localized and severe pain as the lesion advances. Ultimately, chronic lateral patellar tilt can lead to degeneration of the cartilage [5].

It is widely accepted that patellar lateral tilting contributes to the degeneration of the patellofemoral facet cartilage, subsequently resulting in anterior knee pain [6]. The patient presented with anterior knee pain after exercising, exacerbated during squatting or stair climbing. A positive outcome was observed during the patellar grinding test [7]. Place posteriorly directed pressure on the patella, and the knee joint is flex and extend actively and passively to see whether there is crepitation and pain at any point in the flexion arc. However, in addition to the patellofemoral facet cartilage lesions, are there any additional cartilage lesions within other regions of the knee joint? There is a lack of relevant research in this area.

Due to the lack of specific manifestations, ELPS is often misdiagnosed as anterior knee pain, patellofemoral pain syndrome, or chondromalacia. While this classification has some validity, it is not entirely accurate and hinders early diagnosis and treatment. ELPS represents an abnormality in patellar tracking and alignment at a particular stage [1, 8]. Current studies have reported on its clinical manifestations, physical signs, and imaging features [6, 9, 10]. However, there are no significant differences between ELPS and chondromalacia or patellar instability in terms of clinical manifestations and physical signs [11,12,13,14,15]. Radiographic studies typically focus on measuring the position of the patella [5, 16, 17], with no clear reports on characteristic cartilage lesions associated with ELPS [13, 18].

Therefore, this case series study aimed to investigate 141 patients, analyzing their imaging and arthroscopic findings in order to comprehensively summarize the characteristics of cartilage and other knee joint injuries associated with excessive lateral pressure syndrome (ELPS). The ultimate goal is to provide enhanced clinical guidance for diagnosis and treatment at different stages.

Methods

Patients diagnosed with ELPS and admitted to our department between October 1, 2015, and September 30, 2023 and underwent surgical treatment by a single surgeon, were retrospectively included in this study. All patients provided informed consent prior to surgery, and the study protocol was approved by the Ethics Committee of our hospital (batch number: IRB00006761-M2021002). The diagnostic criteria for ELPS were defined as follows:

  1. 1.

    The persistent patellofemoral pain, lasting for over 3 months, exhibited no improvement following conservative treatment.

  2. 2.

    The lateral retinaculum exhibited tightness and tenderness, while the patella demonstrated a medial displacement of less than 1/4th of the trochlea width when the knee was in an extended position and the patella was pushed medially.

  3. 3.

    The imaging revealed lateral tilting of the patella.

  4. 4.

    MRI showed cartilage lesions of knee joint.

  5. 5.

    Arthroscopic observation showed lateral tilting of the patella(the lateral patellofemoral joint space is significantly wider than the medial joint space), and the patella could not return to the normal position when the knee flexed 30°.

The criteria for lateral patellar tilting were: Patellar tilt angle(PTA) > 16°, Patellofemoral Index(PFI) > 1.6. The angles were measured using axial X-ray imaging of the patellofemoral joint, specifically employing the Merchant view technique, with the knee flexed at an angle of 30° [19].

As for lateral retinaculum tightness, we introduced a grading evaluation method:

With the patient in a supine position, the knee joint fully extended and the quadriceps femoris relaxed, the examiner applied horizontal medial pressure to the patella along its lateral border with the thumb.

Grade 0: The patella can be pushed medially by more than 2 cm. This indicates a normal lateral retinaculum.

Grade 1: The patella can be pushed medially by less than 2 cm. This indicates a mild tightened lateral retinaculum.

Grade 2: The patella can be pushed medially only to the extent that the lateral border of the femoral trochlea can be palpated. This indicates a moderate tightened lateral retinaculum.

Grade 3: The thumb is unable to reach the lateral border of the trochlea when the patella is pushed medially. This indicates a severe tighten lateral retinaculum.

It is important to note that this grading evaluation method is currently utilized solely for preliminary clinical assessment, and this study does not include a detailed discussion of the grading system for this test. Future research will focus on conducting an in-depth analysis of this grading system.

Conservative treatment encompasses cryotherapy, patellar taping, analgesics (oral or topical nonsteroidal anti-inflammatory drugs), quadriceps strengthening exercises, and exercises targeting hip abduction and external rotation [3, 20, 21].

After the above criteria, 200 patients were selected for further screening. Exclusion criteria were as follows:

  1. 1.

    Previous history of knee surgery.

  2. 2.

    Cruciate ligament or collateral ligament ruptures.

  3. 3.

    Neoplastic diseases of the knee, such as pigmented vil-lonodular synovitis, etc.

  4. 4.

    Patellar instability, such as recurrent/habitual dislocation of the patella.

  5. 5.

    History of knee fracture.

  6. 6.

    Varus or valgus of the knee joint, or Q angle > 20°.

After further screening based on exclusion criteria, a total of 141 patients (162 knees) were ultimately included in the study (Fig. 1). The age range of the participants varied from 12 to 77 years, with a distribution of 82 males and 59 females. Prior to undergoing arthroscopic examination and extra-capsule lateral retinacular release surgery [22], all included patients underwent magnetic resonance imaging (MRI) examination (3.0-T, uMR 880, United Imaging, 12-channel receiver knee coil) and the images were evaluated by two senior surgeons within our group. Both imaging and surgical procedures focused specifically on the patellofemoral joint, tibiofemoral joint cartilage, and menisci in the affected knee joint.

The MRI images were segmented into specific regions. In the axial plane, the patella was divided into medial (1), central crest (2), and lateral (3) regions. Similarly, in the coronal view, the femur and tibia were divided into medial (M) and lateral (L) regions, delineated by the central point of the femoral trochlear groove and the central ridge of the tibial plateau. Furthermore, both femoral and tibial surfaces were further subdivided into anterior (1), central (2), and posterior (3) regions. The region (1) of the femur corresponds to patellofemoral joint while region (2) represents its weight-bearing surface; only in extreme flexion does region (3) denote a posterior convex surface of this joint. Additionally, region [2] on the tibial surface corresponds to a centrally uncovered part between anterior and posterior horns of meniscus along with its surrounding area covered by meniscus body as depicted in Fig. 2. The same regional division for arthroscopic observation was employed as that used for MRI evaluation.

Regarding lesion grading, the criteria are as follows: (a) Only subchondral bone sclerosis in the T1 phase was considered. In the T2 phase, if there was uneven signal in the cartilage or rough and fissured cartilage surface without a depth exceeding 1/2 of the cartilage thickness, it was classified as (b). Lesions with a depth greater than 1/2 of the cartilage thickness but without full-thickness involvement or exposure of subchondral bone were categorized as (c). A complete defect of cartilage and subchondral bone exposure was recorded as (d). The arthroscopic evaluation followed similar grading standards to those used for MRI assessment (Figs. 3, 4, 5 and 6).

Fig. 1
figure 1

Flowchart of patient inclusion

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Fig. 2
figure 2

Regional division of knee joint lesions A: Schematic illustration of cartilage regions of the knee joint. B: Regional division in the sagittal view of MRI. C: Regional division in the axial view of MRI. D: Regional division in the coronal view of MRI

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Fig. 3
figure 3

Grade (a) lesion in MRI evaluation and arthroscopic observation. A: merely T1 phase subchondral bone sclerosis. B: chondromalacia was found with a probe, but no fissures on the surface of the cartilage

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Fig. 4
figure 4

Grade (b) lesion in MRI evaluation and arthroscopic observation. A: in phase T2, if there was uneven signal in the cartilage, or the cartilage surface was rough and fissured, but the depth did not reach 1/2 of the cartilage thickness, then was recorded as (B). B: fissures on the surface of the cartilage was found

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Fig. 5
figure 5

Grade (c) lesion in MRI evaluation and arthroscopic observation. A: the depth of the cartilage lesion was greater than 1/2 of the thickness of the cartilage, but there was no full-thickness lesion of the cartilage, and the subchondral bone was not exposed, was recorded as (c). B: cartilage lesion was found greater than 1/2 of the thickness of the cartilage, subchondral bone was not exposed

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Fig. 6
figure 6

Grade (d) lesion in MRI evaluation and arthroscopic observation. A: full-thickness cartilage defects with subchondral bone exposure were recorded as (d). B: full-thickness cartilage defects were found under arthroscopic observation, subchondral bone was exposed

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The lesion regions and corresponding lesion grading of each knee joint were meticulously documented, and the concordance between imaging and arthroscopic evaluation was quantified. The overall incidence of lesions in each region was recorded. Based on gender, patients were stratified into male and female groups, allowing for a comparison of lesion distribution between the two groups. Furthermore, all patients were categorized based on age: <20 years old, 20–50 years old, > 50 years old; enabling a comparison of lesion distribution among these three age groups. The frequency distribution across different regions will be thoroughly described and compared.

Statistical analysis

The statistical analysis was performed using SPSS 24.0 software. The normal distribution of data was assessed using the Kolmogorov-Smirnov test, with (x ± s) representing measurement data that followed a normal distribution and M (QR) representing non-normally distributed measurement data. Descriptive statistics were reported as means, standard deviations, counts, or proportions. Categorical variables were compared using the chi-square test, while numerical values between groups were compared using the student t-test. Statistical significance was defined as p < 0.05.

Results

Demographic statistics

Among all the included patients, there were 82 male participants with an average age of 34.87 ± 13.70 years and 59 female participants with an average age of 35.46 ± 16.55 years. In the male group, there were 42 left knees and 52 right knees, while in the female group, there were 34 left knees and 34 right knees. No significant differences in age or side distribution were observed between the two groups (Table 1).

Table 1 Groups categorized by gender and comparison
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According to age, the enrolled patients were categorized into three groups: <20 years old, 20–50 years old, and > 50 years old. There were no statistically significant differences observed among these three groups in terms of gender or affected side (Table 2).

Table 2 Groups categorized by age and comparison
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The incidence of lesions in each region of the knee joint

The MRI imaging and arthroscopic observations were conducted on all 141 patients (162 knees) based on the aforementioned partitions, with detailed recording of lesion occurrences and calculation of lesion incidences in each region. In MRI imaging, the highest incidence happened in the central part of medial tibial plateau (93.80%), the second highest incidence was in the posterior region of lateral tibial plateau (89.5%), the third highest incidence was in the central crest of patella (74.10%). These regions had significantly higher incidences than other regions. In the arthroscopic observation, the highest incidence happened in the central part of medial tibial plateau and the posterior region of lateral tibial plateau, they had the same incidences (both 80.90%). The second highest incidence was in the lateral facet of patella (59.20%), and the third highest incidence was in the central crest of patella (56.20%). The results are presented in Tables 3 and 4. The reliability between radiographic and arthroscopic incidences was assessed, yielding an ICC value of 0.979 (95% CI: 0.948–0.992, P = 0.071), indicating excellent agreement.

Table 3 Overall MRI evaluation incidence of lesions for each region
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Table 4 Overall arthroscopic incidence of lesions for each region
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The incidence of males and females was recorded separately. Out of a total of 162 knees, 94 were male and 68 were female. Table 5 presents the incidence of radiographic observations, while Table 6 displays the incidence of arthroscopic observations. In MRI imaging, for male group, the highest incidence happened in the central part of medial tibial plateau (92.60%), the second highest incidence was in the posterior region of lateral tibial plateau (90.40%), and the third highest incidence was in the central crest of patella (71.30%). In the female group, the highest incidence happened in the central part of medial tibial plateau (95.60%), the second highest incidence was in the posterior region of lateral tibial plateau (88.20%), and the third highest incidence was in the central crest of patella (77.90%). Both in male group and female group, there were similar incidence distributions for MRI imaging. As for arthroscopic observation, for male group, the highest incidence happened in the posterior region of lateral tibial plateau (81.90%), the second highest incidence was in the central part of medial tibial plateau (79.80%), the third highest incidence was in the lateral facet of patella (57.40%), and the fourth highest incidence was in the central crest of patella (52.10%). In the female group, the highest incidence happened in the central part of medial tibial plateau (95.60%), the second highest incidence was in the posterior region of lateral tibial plateau (88.20%), the third highest incidence was in the central crest of patella and the lateral facet of patella (61.80%). All these regions had significantly higher incidences than other regions. Regarding gender comparison, there were no statistically significant differences in imaging observations (P = 0.940). Similarly, no statistically significant differences were observed under arthroscopic examinations (P = 0.237).

Table 5 MRI evaluation incidence of lesions for each region in comparison of genders
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Table 6 Arthroscopic incidence of lesions for each region in comparison of genders
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According to age, the patients were categorized into three groups: <20 years old group, 20–50 years old group, and > 50 years old group. The numbers of cases in each group were 27, 103, and 32, respectively. The incidence of radiographic and arthroscopic lesions was documented for each group, with the results presented in Tables 7 and 8. In MRI imaging, for < 20 years old group, the highest incidence happened in the central part of medial tibial plateau(92.60%), the second highest incidence was in the central crest of patella(88.90%), and the third highest incidence was in the posterior region of lateral tibial plateau (85.20%), the fourth highest incidence was in the lateral facet of patella (81.50%). For 20–50 years old group, the highest incidence happened in the central part of medial tibial plateau (93.20%), the second highest incidence was in the posterior region of lateral tibial plateau (92.20%), and the third highest incidence was in the central crest of patella (72.80%). For > 50 years old group, the highest incidence happened in the central part of medial tibial plateau (96.90%), the second highest incidence was in the posterior region of lateral tibial plateau (84.40%), and the third highest incidence was in the medial facet of patella (71.90%), and the fourth highest incidence was in the central crest of patella (65.60%). As for arthroscopic observation, for < 20 years old group, the highest incidence happened in the central part of medial tibial plateau (85.20%), the second highest incidence was in the lateral facet of patella (81.40%), and the third highest incidence was in the posterior region of lateral tibial plateau (74.10%). For 20–50 years old group, the highest incidence happened in the posterior region of lateral tibial plateau (83.50%), the second highest incidence was in the central part of medial tibial plateau (79.60%), and the third highest incidence was in the lateral facet of patella (54.40%). For > 50 years old group, the highest incidence happened in the central part of medial tibial plateau (81.30%), the second highest incidence was in the posterior region of lateral tibial plateau (78.10%), and the third highest incidence was in the medial facet of patella and central crest of patella (both 62.50%). All these regions had significantly higher incidences than other regions.

There were no statistically significant differences observed in radiographic incidences among all three groups. However, during arthroscopic examination, a significantly higher incidence was found in individuals aged over 50 compared to both those under 20 and those aged between 20 and 50 (P = 0.015, P = 0.018). Conversely, there were no significant differences detected between individuals under 20 and those aged between 20 and 50 (P = 0.198).

Table 7 MRI evaluation incidence of lesions for each region
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Table 8 Arthroscopic incidence of lesions for each region
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The incidence of different grades of lesions in each region of the knee joint

According to age, the patients were categorized into three groups: <20 years old group, 20–50 years old group, and > 50 years old group. The numbers of cases in each group were 27, 103, and 32, respectively. We recorded the incidence of different grades of lesions in each region through both radiographic observation and arthroscopic observation using Grades a to d as previously described. The detailed results are presented in Fig. 7A-H.

Fig. 7
figure 7

Radiographic and arthroscopic incidence of different grades of lesions for each region. A-D: Radiographic incidence for each region from grade a to d respectively. E-H: Arthroscopic incidence for each region from grade a to d respectively

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Discussion

The excessive lateral pressure syndrome (ELPS) of the patella was initially reported by Ficat et al. [6, 10]. It has been postulated that the contracture of the lateral retinaculum of the patella leads to lateral tilting, resulting in a series of anterior knee pain and patellofemoral articular cartilage lesions [11]. Subsequently, numerous studies have focused on its diagnosis, imaging techniques, and surgical interventions. However, there is currently no existing literature reporting on the characteristics of cartilage lesions in ELPS. Biomechanical studies have demonstrated a correlation between patellar mal-tracking and lower limb rotation, which in turn leads to alterations in tibiofemoral joint facet pressure [2, 23,24,25,26]. Based on this premise, we postulate that the presence of tibiofemoral articular cartilage lesions is associated with changes in both tibiofemoral joint stress and excessive lateral patellar tilt (ELPS). Consequently, our aim is to validate these findings by providing a comprehensive analysis of the characteristics of ELPS-related lesions within this study.

After screening, a total of 141 patients and 162 knees were included in this study. Among them, there were 82 male and 59 female patients. No significant differences were observed between the two groups in terms of side or age. The included patients were categorized into three groups based on age: <20 years old, 20–50 years old, and > 50 years old. There were no statistically significant differences among these three age groups regarding gender or side.

The overall incidence of cartilage injury showed good consistency between MRI evaluation and arthroscopic observation (ICC = 0.979, 95% CI 0.948–0.992, P = 0.071). Notably, both MRI evaluation and arthroscopic observation consistently identified the patella, central region of the medial tibial plateau, and posterior region of the lateral tibial plateau as having the highest incidence of cartilage injury. Specifically, the incidence in the central region of the medial tibial plateau was found to be 93.80% (MRI evaluation) and 80.90% (arthroscopic observation). The incidence of the posterior region of the lateral tibial plateau was 89.50% (MRI evaluation) and 80.90% (Arthroscopic observation). As observed, the incidence in specific regions exhibited discrepancies between MRI evaluation and arthroscopic observation. However, the ICC demonstrated high consistency because our comparison focused on the overall frequency rather than on specific individual regions. Our primary goal for consistency comparisons was to validate the assessments and not to seek a point-to-point correspondence between MRI findings and arthroscopic findings in each region. For early-stage cartilage lesions, MRI has a lower sensitivity than arthroscopy [27, 28]. To solve this problem, we conducted a stratified comparison of different stages of cartilage lesions to reduce the influence of this difference, so as to not affect the accuracy of the overall results.

In the comparison of gender groups, the incidence of lesions in the central region of the medial tibial plateau and posterior region of the lateral tibial plateau was found to be significantly higher, with no statistically significant difference observed between the two groups (P > 0.05). Similarly, when comparing different age groups, it was observed that these two regions also had the highest incidence of lesions across all three age groups, without any significant variation among them (P > 0.05). These cartilage lesions in specific regions of the tibial plateau may be associated with internal tibial rotation. Patellar mal-tracking and lower limb rotation may significantly influence the contact area and pressure of patellofemoral and tibiofemoral joint [29, 30]. Typically, cartilage lesions in the tibial plateau are predominantly located in the central region, which corresponds to the weight-bearing area. However, in patients with ELPS, the lesion on the lateral tibial plateau is notably more posterior. Therefore, we hypothesize that the lateral tilting of the patella induces internal tibial rotation, leading to this distinct pattern of cartilage injury. We plan to validate this hypothesis through future biomechanical studies using finite element analysis or cadaveric study.

The central crest of the patella exhibited the highest incidence of patellar cartilage lesions in both the < 20 years old group and 20–50 years old group, with no significant gender difference observed. However, in the > 50 years old group, the medial region of the patella showed the highest incidence of patellar cartilage injury. Based on these findings, we hypothesized that under conditions of lateral patellar tilt, different regions of patellar cartilage are exposed to distinct types of stress. The central crest of the patella is subjected to a higher concentration of shear stress within the patellofemoral joint, leading to an elevated risk of cartilage degeneration in younger or early-stage patients. The lateral facet underwent high vertical stress, leading to cartilage lesion; however, this process progresses more slowly compared to the effects of shear stress. Regarding the medial facet, the lateral tilting of the patella resulted in stress deprivation, which gradually led to cartilage degeneration. However, this process progresses more slowly compared to the other two regions. These hypotheses require further biomechanical studies for confirmation.

For cartilage lesion grading, we adopted the Outerbridge classification of cartilage lesions [31, 32], excluding Grade 0 as our study did not include normal cartilage. Additionally, we referred to the ICRS grading system [33], but omitted subchondral bone edema from consideration since it can only be observed via MRI and is difficult to confirm during arthroscopy, thereby precluding reliable consistency comparisons. In the comparison of lesion grading, younger or early patients predominantly exhibited Grade a and Grade b lesions, whereas older patients (> 50 years old) primarily presented with Grade c and Grade d lesions. We conducted an analysis on the incidence of Grade d and observed that both radiographic evaluation and arthroscopic observation demonstrated a significantly higher incidence in the > 50 years old group compared to the < 20 years old group and 20–50 years old group (P < 0.05). However, there was no significant difference between the < 20 years old group and 20–50 years old group (P = 0.055, 0.118). It was evident that the prevalence of full-thickness cartilage defects significantly increased with advancing age.

We did not include analyses of body-mass index (BMI) and exercise habits in our study for several reasons. Primarily, the objective of this study was to investigate the relationship between patellar lateral tilting and excessive lateral pressure syndrome, as well as the associated cartilage lesions in specific regions of the tibial plateau, and to summarize the characteristics of cartilage lesions in cases of excessive lateral pressure syndrome. This study was not designed to comprehensively examine all potential pathogenic factors for osteoarthritis. Consequently, BMI and exercise habits were excluded from the analyses. Secondly, this study aimed to uncover a direct association between lateral patellar tilt and tibial plateau cartilage lesions, a relationship that remains underexplored in prior research. While the effects of BMI and exercise habits on knee cartilage damage have been extensively investigated [34, 35], we concentrated our analysis on the primary anatomical and pathological characteristics to ensure the depth and focus of the study. Finally, given the retrospective nature of this study, the data were extracted from pre-existing medical records, which lacked information on BMI and exercise habits. Consequently, while these factors might have influenced the study outcomes, they could not be incorporated into the analysis owing to the absence of relevant data.Furthermore, we observed a coexistence of horizontal tears in the posterior horn of the meniscus among patients with EPLS, which exhibited no correlation with age or gender and lacked any apparent history of knee trauma. It has been reported that knee joint line obliquity can result in changes to the contact area of the tibiofemoral joint, potentially leading to meniscus injury [36]. However, this study excluded patients with abnormal knee alignment. Further investigation is warranted to explore potential biomechanical alterations within the knee joint contributing to this injury occurrence.

There is a lack of literature reporting on the biomechanical effects of excessive lateral pressure syndrome on the tibial plateau. However, prior studies have demonstrated a direct relationship between tibiofemoral joint kinematics and patellofemoral joint contact pressure [37]. Additionally, tibial posterior displacement and rotation have been shown to be associated with changes in patellofemoral joint contact pressure [29]. Furthermore, it has been documented that lower limb rotational alignment significantly influences the contact pressure within the medial tibiofemoral compartment of the knee joint [16]. Based on these reports, we hypothesize that the lateral tilting of the patella influences both the contact area and stress distribution within the tibiofemoral joint. Future studies, including cadaveric analyses and animal experiments, will be conducted to validate this hypothesis and elucidate the biomechanical implications of patellar lateral tilt on the tibiofemoral joint.

Currently, finite element analysis of the knee joint has reached a relatively advanced level; however, research on lateral patellar tilt and excessive lateral pressure syndrome remains scarce. Numerous finite element models have been developed to simulate the changes in pressure and contact area of the patellofemoral and tibiofemoral joints during the flexion and extension of both normal and abnormal knee joints [38, 39]. Additionally, finite element analyses have explored the effects of lateral retinacular release on patellofemoral joint stress [40]. Nevertheless, the impact of excessive lateral pressure syndrome on tibiofemoral joint stress remains largely unexplored and underreported. In future studies, we aim to investigate the biomechanical effects of excessive lateral pressure syndrome on the tibiofemoral joint using MRI-based modeling combined with finite element analysis.

Conclusions

In addition to patellofemoral joint cartilage lesions, excessive lateral pressure syndrome (ELPS) of the patella can also cause cartilage lesions in the central region of the medial tibial plateau and posterior region of the lateral tibial plateau. These specific sites of lesion are not influenced by gender or age. The incidence of full-thickness cartilage defects gradually increases with age. Further biomechanical studies are needed to determine the specific mechanisms underlying these conditions.

Limitations

This study had limitations. No control group was established in this study, precluding the possibility of conducting a case-control study. Given that arthroscopic evaluation was required for this study, patients who only received conservative treatment were excluded, which may introduce potential bias. Future research will aim to conduct prospective cohort studies, which provide a higher level of evidence.

Data availability

No datasets were generated or analysed during the current study.

Abbreviations

PFPS:

patellofemoral pain syndrome

ELPS:

excessive lateral pressure syndrome

MRI:

magnetic resonance imaging

PTA:

patellar tilt angle

PFI:

patellofemoral Index

References

  1. Kasitinon D, Li WX, Wang EXS, Fredericson M. Physical examination and patellofemoral pain syndrome: an updated review. Curr Rev Musculoskelet Med. 2021;14(6):406–12. https://doiorg.publicaciones.saludcastillayleon.es/10.1007/s12178-021-09730-7.

    Article  PubMed  PubMed Central  Google Scholar 

  2. Boden BP, Pearsall AW, Garrett WE Jr., Feagin JA. Jr. Patellofemoral instability: evaluation and management. J Am Acad Orthop Surg. 1997;5(1):47–57. https://doiorg.publicaciones.saludcastillayleon.es/10.5435/00124635-199701000-00006.

    Article  CAS  PubMed  Google Scholar 

  3. Barton C, Balachandar V, Lack S, Morrissey D. Patellar taping for patellofemoral pain: a systematic review and meta-analysis to evaluate clinical outcomes and Biomechanical mechanisms. Br J Sports Med. 2014;48(6):417–24. https://doiorg.publicaciones.saludcastillayleon.es/10.1136/bjsports-2013-092437.

    Article  PubMed  Google Scholar 

  4. Dandu N, Trasolini NA, DeFroda SF, Darwish RY, Yanke AB. The lateral side: when and how to release, lengthen, and reconstruct. Clin Sports Med. 2022;41(1):171–83. https://doiorg.publicaciones.saludcastillayleon.es/10.1016/j.csm.2021.07.007.

    Article  PubMed  Google Scholar 

  5. Grelsamer RP, Klein JR. The biomechanics of the patellofemoral joint. J Orthop Sports Phys Ther. 1998;28(5):286–98. https://doiorg.publicaciones.saludcastillayleon.es/10.2519/jospt.1998.28.5.286.

    Article  CAS  PubMed  Google Scholar 

  6. Ficat P, Ficat C, Bailleux A. [External hypertension syndrome of the patella. Its significance in the recognition of arthrosis]. Rev Chir Orthop Reparatrice Appar Mot. 1975;61(1):39–59.

  7. Larson RL, Cabaud HE, Slocum DB, James SL, Keenan T, Hutchinson T. The patellar compression syndrome: surgical treatment by lateral retinacular release. Clin Orthop Relat Res. 1978;134:158–67.

  8. Ficat RP, Philippe J, Hungerford DS. Chondromalacia patellae: a system of classification. Clin Orthop Relat Res. 1979;144:55–62.

  9. Cancienne JM, Christian DR, Redondo ML, Huddleston HP, Shewman EF, Farr J, et al. The Biomechanical effects of limited lateral retinacular and capsular release on lateral patellar translation at various flexion angles in cadaveric specimens. Arthrosc Sports Med Rehabilitation. 2019;1(2):e137–44. https://doiorg.publicaciones.saludcastillayleon.es/10.1016/j.asmr.2019.09.002.

    Article  Google Scholar 

  10. Ficat P. [The syndrome of lateral hyperpressure of the patella]. Acta Orthop Belg. 1978;44(1):65–76.

    CAS  PubMed  Google Scholar 

  11. Fulkerson JP. Evaluation of the peripatellar soft tissues and retinaculum in patients with patellofemoral pain. Clin Sports Med. 1989;8(2):197–202.

    Article  CAS  PubMed  Google Scholar 

  12. Fulkerson JP. Diagnosis and treatment of patients with patellofemoral pain. Am J Sports Med. 2002;30(3):447–56. https://doiorg.publicaciones.saludcastillayleon.es/10.1177/03635465020300032501.

    Article  PubMed  Google Scholar 

  13. Fulkerson JP, Gossling HR. Anatomy of the knee joint lateral retinaculum. Clin Orthop Relat Res. 1980;153:183–8.

  14. Grelsamer RP, Weinstein CH, Gould J, Dubey A. Patellar Tilt: the physical examination correlates with MR imaging. Knee. 2008;15(1):3–8. https://doiorg.publicaciones.saludcastillayleon.es/10.1016/j.knee.2007.08.010.

    Article  PubMed  Google Scholar 

  15. Insall J, Salvati E. Patella position in the normal knee joint. Radiology. 1971;101(1):101–4. https://doiorg.publicaciones.saludcastillayleon.es/10.1148/101.1.101.

  16. Kenawey M, Liodakis E, Krettek C, Ostermeier S, Horn T, Hankemeier S. Effect of the lower limb rotational alignment on tibiofemoral contact pressure. Knee Surg Sports Traumatol Arthroscopy: Official J ESSKA. 2011;19(11):1851–9. https://doiorg.publicaciones.saludcastillayleon.es/10.1007/s00167-011-1482-4.

    Article  Google Scholar 

  17. Kramer PG. Patella malalignment syndrome: rationale to reduce excessive lateral pressure. J Orthop Sports Phys Ther. 1986;8(6):301–9. https://doiorg.publicaciones.saludcastillayleon.es/10.2519/jospt.1986.8.6.301.

    Article  CAS  PubMed  Google Scholar 

  18. Fulkerson JP, Tennant R, Jaivin JS, Grunnet M. Histologic evidence of retinacular nerve injury associated with patellofemoral malalignment. Clin Orthop Relat Res. 1985;197:196–205.

  19. Merchant AC, Mercer RL, Jacobsen RH, Cool CR. Roentgenographic analysis of patellofemoral congruence. J Bone Joint Surg Am Volume. 1974;56(7):1391–6.

    Article  CAS  Google Scholar 

  20. Manojlović D, Kozinc Ž, Šarabon N, Trunk. Hip and knee exercise programs for pain relief, functional performance and muscle strength in patellofemoral pain: systematic review and Meta-Analysis. J Pain Res. 2021;14:1431–49. https://doiorg.publicaciones.saludcastillayleon.es/10.2147/jpr.S301448.

    Article  PubMed  PubMed Central  Google Scholar 

  21. Nakagawa TH, Muniz TB, Baldon Rde M, Dias Maciel C, de Menezes Reiff RB, Serrão FV. The effect of additional strengthening of hip abductor and lateral rotator muscles in patellofemoral pain syndrome: a randomized controlled pilot study. Clin Rehabil. 2008;22(12):1051–60. https://doiorg.publicaciones.saludcastillayleon.es/10.1177/0269215508095357.

    Article  PubMed  Google Scholar 

  22. Minghao L, Zhenxing S, Qiang L, Guoqing C. Lateral retinacular release for treatment of excessive lateral pressure syndrome: the Capsule-Uncut immaculate (CUI) technique. Arthrosc Techniques. 2023;12(11):e1991-e6. https://doiorg.publicaciones.saludcastillayleon.es/10.1016/j.eats.2023.07.018.

    Article  Google Scholar 

  23. Merchant AC. Classification of patellofemoral disorders. arthroscopy: the journal of arthroscopic & related surgery: official publication of the arthroscopy association of North America. Int Arthrosc Association. 1988;4(4):235–40. https://doiorg.publicaciones.saludcastillayleon.es/10.1016/s0749-8063(88)80037-9.

    Article  CAS  Google Scholar 

  24. Merchant AC, Mercer RL. Lateral release of the patella. A preliminary report. Clin Orthop Relat Res. 1974;10340–5. https://doiorg.publicaciones.saludcastillayleon.es/10.1097/00003086-197409000-00027.

  25. Wünschel M, Leichtle U, Obloh C, Wülker N, Müller O. The effect of different quadriceps loading patterns on tibiofemoral joint kinematics and patellofemoral contact pressure during simulated partial weight-bearing knee flexion. Knee surgery, sports traumatology, arthroscopy. Official J ESSKA. 2011;19(7):1099–106. https://doiorg.publicaciones.saludcastillayleon.es/10.1007/s00167-010-1359-y.

    Article  Google Scholar 

  26. Kolowich PA, Paulos LE, Rosenberg TD, Farnsworth S. Lateral release of the patella: indications and contraindications. Am J Sports Med. 1990;18(4):359–65. https://doiorg.publicaciones.saludcastillayleon.es/10.1177/036354659001800405.

    Article  CAS  PubMed  Google Scholar 

  27. Figueroa D, Calvo R, Vaisman A, Carrasco MA, Moraga C, Delgado I. Knee Chondral lesions: incidence and correlation between arthroscopic and magnetic resonance findings. Arthroscopy: J Arthroscopic Relat Surg: Official Publication Arthrosc Association North Am Int Arthrosc Association. 2007;23(3):312–5. https://doiorg.publicaciones.saludcastillayleon.es/10.1016/j.arthro.2006.11.015.

    Article  Google Scholar 

  28. Danieli MV, Guerreiro JP, Queiroz A, Pereira H, Tagima S, Marini MG et al. Diagnosis and classification of Chondral knee injuries: comparison between magnetic resonance imaging and arthroscopy. Knee surgery, sports traumatology, arthroscopy: official journal of the ESSKA. 2016;24(5):1627–33https://doiorg.publicaciones.saludcastillayleon.es/10.1007/s00167-015-3622-8

  29. Lee TQ, Morris G, Csintalan RP. The influence of tibial and femoral rotation on patellofemoral contact area and pressure. J Orthop Sports Phys Ther. 2003;33(11):686–93. https://doiorg.publicaciones.saludcastillayleon.es/10.2519/jospt.2003.33.11.686.

    Article  PubMed  Google Scholar 

  30. Pohlig F, Lenze U, Lenze FW, Lazic I, Haug A, Hinterwimmer S, et al. Arthroscopic lateral retinacular release improves patello-femoral and femoro-tibial kinematics in patients with isolated lateral retinacular tightness. Knee Surg Sports Traumatol Arthroscopy: Official J ESSKA. 2022;30(3):791–9. https://doiorg.publicaciones.saludcastillayleon.es/10.1007/s00167-021-06434-w.

    Article  Google Scholar 

  31. Outerbridge RE. The etiology of chondromalacia patellae. J Bone Joint Surg Br Volume. 1961;43–b:752–7. https://doiorg.publicaciones.saludcastillayleon.es/10.1302/0301-620x.43b4.752.

  32. Slattery C, Kweon CY. Classifications in brief: outerbridge classification of Chondral lesions. Clin Orthop Relat Res. 2018;476(10):2101–4. https://doiorg.publicaciones.saludcastillayleon.es/10.1007/s11999.0000000000000255.

    Article  PubMed  PubMed Central  Google Scholar 

  33. Pritzker KP, Gay S, Jimenez SA, Ostergaard K, Pelletier JP, Revell PA, et al. Osteoarthritis cartilage histopathology: grading and staging. Osteoarthr Cartil. 2006;14(1):13–29. https://doiorg.publicaciones.saludcastillayleon.es/10.1016/j.joca.2005.07.014.

    Article  CAS  Google Scholar 

  34. Dong Y, Yan Y, Zhou J, Zhou Q, Wei H. Evidence on risk factors for knee osteoarthritis in middle-older aged: a systematic review and meta analysis. J Orthop Surg Res. 2023;18(1):634. https://doiorg.publicaciones.saludcastillayleon.es/10.1186/s13018-023-04089-6.

    Article  PubMed  PubMed Central  Google Scholar 

  35. Godziuk K, Hawker GA. Obesity and body mass index: past and future considerations in osteoarthritis research. Osteoarthr Cartil. 2024;32(4):452–9. https://doiorg.publicaciones.saludcastillayleon.es/10.1016/j.joca.2024.02.003.

    Article  Google Scholar 

  36. Wang D, Willinger L, Athwal KK, Williams A, Amis AA. Knee joint line obliquity causes tibiofemoral subluxation that alters contact areas and meniscal loading. Am J Sports Med. 2021;49(9):2351–60. https://doiorg.publicaciones.saludcastillayleon.es/10.1177/03635465211020478.

    Article  PubMed  PubMed Central  Google Scholar 

  37. Li G, DeFrate LE, Zayontz S, Park SE, Gill TJ. The effect of tibiofemoral joint kinematics on patellofemoral contact pressures under simulated muscle loads. J Orthop Research: Official Publication Orthop Res Soc. 2004;22(4):801–6. https://doiorg.publicaciones.saludcastillayleon.es/10.1016/j.orthres.2003.11.011.

  38. Kothurkar R, Lekurwale R, Gad M, Rathod CM. Finite element analysis of a healthy knee joint at deep squatting for the study of tibiofemoral and patellofemoral contact. J Orthop. 2023;40:7–16. https://doiorg.publicaciones.saludcastillayleon.es/10.1016/j.jor.2023.04.016.

    Article  PubMed  PubMed Central  Google Scholar 

  39. Yan M, Liang T, Zhao H, Bi Y, Wang T, Yu T, et al. Model properties and clinical application in the finite element analysis of knee joint: A review. Orthop Surg. 2024;16(2):289–302. https://doiorg.publicaciones.saludcastillayleon.es/10.1111/os.13980.

    Article  PubMed  PubMed Central  Google Scholar 

  40. Chen YF, Lu C, Zhao Y, Cheng YZ, Qiao F, Hou CZ, et al. [Finite element analysis on stress concentration improvement in patellofemoral joint by releasing lateral patellar retinaculum with stiletto needle based on the theory of Jinshugu()]. Zhongguo Gu shang = china. J Orthop Traumatol. 2021;34(2):126–30. https://doiorg.publicaciones.saludcastillayleon.es/10.12200/j.issn.1003-0034.2021.02.006.

    Article  Google Scholar 

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Acknowledgements

I would like to express my sincere gratitude to Dr. Zhang Hua for his invaluable assistance and guidance throughout this study.

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Author notes

  1. Li Minghao is the first author of this article.

Authors and Affiliations

  1. Department of Sports Medicine, Peking University Third Hospital, Institute of Sports Medicine of Peking University, Beijing, China

    Li Minghao, Liu Qiang & Cui Guoqing

  2. Beijing Key Laboratory of Sports Injuries, Beijing, China

    Li Minghao, Liu Qiang & Cui Guoqing

  3. Engineering Research Center of Sports Trauma Treatment Technology and Devices, Ministry of Education, Beijing, China

    Li Minghao, Liu Qiang & Cui Guoqing

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  1. Li Minghao
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  3. Cui Guoqing
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Contributions

C.G: Methodology, Project administration and Supervision. L.Q: Review and editing. L.M: Writing the original draft, Formal analysis, Data curation and Visualization.

Corresponding authors

Correspondence to Liu Qiang or Cui Guoqing.

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The Ethics Committee of the Third Hospital of Peking University approved this study. (No.: IRB00006761-M2021002)

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Minghao, L., Qiang, L. & Guoqing, C. Lateral patellar tilting can also result in cartilage lesions of tibial plateau - the characteristic features of excessive lateral pressure syndrome: a retrospective study of 141 cases. BMC Musculoskelet Disord 26, 443 (2025). https://doiorg.publicaciones.saludcastillayleon.es/10.1186/s12891-025-08686-w

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Keywords

BMC Musculoskeletal Disorders

ISSN: 1471-2474

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