Arthroscopic lateral retinacular release improves patello-femoral and femoro-tibial kinematics in patients with isolated lateral retinacular tightness

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

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.

Partial LRR over complete LRR: a preferable option - an FEA study of A - B trochlear dysplasia with critical abnormalities of patella alta and TT - TG value

Objective

This study analyzed the effects of medial patellofemoral ligament (MPFL) injury and varying degrees of lateral retinacular release (LRR) on patellofemoral joint (PFJ) contact pressure using finite element analysis (FEA).

Methods

A PFJ FE model was developed and validated at four knee flexion angles (0°, 30°, 60°, and 90°) using imaging data from a patient with A-B trochlear dysplasia and critical abnormalities of patella alta and tubercle-trochlear groove (TT-TG) value. MPFL injury was simulated by inhibiting its function, while LRR was modeled by adjusting the stiffness of the lateral retinaculum. Changes in PFJ contact pressure were systematically analyzed.

Results

At 0° flexion, LRR led to increased PFJ pressure with an intact MPFL, whereas it resulted in a reduction with a ruptured MPFL. At 30° flexion, partial LRR didn't elevate PFJ pressure when MPFL was intact, while complete LRR did with both intact and ruptured MPFL. At 60° flexion, partial LRR effectively reduced PFJ pressure, but complete release reversed this effect. At 90° flexion, PFJ pressure increased with the extent of LRR, irrespective of MPFL integrity. Specifically, complete LRR led to an increase in medial pressure, resulting in a shift of the pressure center from lateral to medial at 30° and 60° flexion.

Clinical Implications

This study provides new theoretical basis for the expected outcomes of varying degrees of LRR, which helps clinicians better conduct preoperative planning, especially in avoiding over - aggressive LRR procedures which may not yield improved outcomes.

Conclusion

In patients with A- B trochlear dysplasia and critical abnormalities, excessive LRR does not consistently lower PFJ pressure but rather increases medial compartment pressure, suggesting that partial release may be a more effective and precise surgical approach in these patients.

The patellar compression angle: a new, accurate diagnostic angle for lateral patellar compression syndrome

BACKGROUND

Lateral patellar compression syndrome (LPCS) is a common cause of anterior knee pain. Early diagnosis of LPCS using an accurate radiological examination is, therefore, important. However, the currently used radiological examinations for detecting LPCS are poor diagnostic indicators. Therefore, the aim of this study was to establish a new diagnostic imaging examination for LPCS and evaluate its accuracy in comparison with conventional examinations.

METHODS

From June 2020 to May 2023, a retrospective analysis was conducted on 72 patients in the LPCS group and 140 patients in the Control group, all of whom underwent axial radiographs of the patella and knee MRI. The patellar compression angle (PCA), Tilting angle (TA), Congruence angle (CA), Grelsamer angle (AG), and Lateral patellofemoral angle (LPA) were used and compared statistically for their accuracy in terms of diagnosing LPCS.

RESULTS

The area under the receiver operating characteristic curve (ROC) for the PCA was 0.87, which was the highest among the five examinations. ROC analysis revealed that a smaller PCA, less than 14.7°, was associated with LPCS, with the highest sensitivity (80.6%), specificity (82.9%), accuracy (82.1%), positive predictive value (PPV, 70.7%), negative predictive value (NPV, 89.2%), positive likelihood ratio (PLR, 4.71), and lowest negative likelihood ratio (NLR, 0.23) compared with the other four examinations. The interobserver reproducibility of the PCA was good, with an intraclass correlation coefficients (ICCs) of 0.85.

CONCLUSIONS

The PCA can detect LPCS with a moderate diagnostic performance and could, therefore, might be a new angle for the diagnosis of LPCS in clinical settings.