The synovial fold of the distal tibiofibular joint: A morphometric study

The tibiofibular mortise - anatomical controversies and their clinical importance: a historical and pictorial essay

INTRODUCTION

During 280 years of studies of the anatomy of the distal tibiofibular articulation, there have arisen many unclear issues regarding the description of individual structures and their terminology. These historical inaccuracies were subsequently reflected in the clinical practice.

MATERIALS AND METHODS

A literature search of original publications and historical sources was performed.

RESULTS

The distal tibiofibular articulation is a synovial joint, rather than a syndesmosis, as it is an integral part of the ankle joint. The interosseous tibiofibular ligament (ITFL), described for the first time by a French anatomist Bichat in 1801, is the strongest ligament of the tibiofibular mortise. Unfortunately, this clinically important ligament is not recognized by the current international anatomical nomenclature. The terms anterior inferior (AITFL) and posterior inferior tibiofibular ligaments (PITFL) are historical remnants "reimported" from the American/British literature and should not be used, because the analogous superior ligaments do not exist. The intermalleolar ligament, first described by Weitbrecht in 1742, is a variable, but constant, structure reinforcing the posterior capsule of the ankle joint. The term inferior transverse ligament (IFT) denoting in the English literature the inferior part of the posterior tibiofibular ligament was originally used for the intermalleolar ligament. The IFT ligament is a part of the posterior tibiofibular ligament and there is no reason to stress its importance.

CONCLUSION

The chaos in the anatomy, terminology and depiction of the articulation of the distal tibia and fibula, unparalleled in any other joint of the human body, is the result of historical development. A certain negative role was, in this respect, played also by Basiliensia Nomina Anatomica (1895), that eradicated ITFL and called the distal tibiofibular joint a syndesmosis.

Anatomical variants of the medial synovial fold of the posterior cruciate ligament: morphological classification based on magnetic resonance imaging of the knee

PURPOSE

The medial synovial fold of the posterior cruciate ligament is one of the synovial plicae of the knee joint. The objective of this study was to assess the necessity of reporting the appearance of the medial synovial fold of the posterior cruciate ligament on magnetic resonance imaging of the knee joint and its correlation with side and sex.

METHODS

Patients with normal knee structure on magnetic resonance imaging (MRI) scans between 2018 and 2023 were included in this retrospective study. MRI scans of the knee joints were retrospectively reviewed by two musculoskeletal radiologists independently. The medial synovial fold of the posterior cruciate ligament was divided into three types according to the imaginary line drawn between the lateral border of the medial femoral condyle and the medial tibial intercondylar tubercle.

RESULTS

The study included 1147 patients, of whom 478 (41.7%) were female and 669 (58.3%) were male. Among these patients, 580 (50.6%) had a right knee scan, and 567 (49.4%) had a left knee scan. The age range was 15-35 years for both sexes. The frequency of the medial synovial fold types in all patients was as follows: Type A (30.1%), Type B (55.4%) and Type C (14.5%). There was a high level of agreement between the observers. There was a statistically significant difference in the frequency of medial synovial fold types between sexes, with men exhibiting a greater prevalence.

CONCLUSION

Magnetic resonance imaging (MRI) of the knee joint revealed the medial synovial folds of the posterior cruciate ligament (PCL). The most common was Type B (55.4%), followed by Type A (30.1%) and Type C (14.5%) among the MSF types. No statistically significant difference was found between the right and left knees for any of the MSF types.

Medial Synovial Fold of the Posterior Cruciate Ligament on Knee Magnetic Resonance Imaging and Arthroscopy: Retrospective Investigation of Impingement

OBJECTIVE

The purpose of this study was to classify the types of medial synovial fold of the posterior cruciate ligament (PCL) on magnetic resonance imaging (MRI) and to identify the relationships between fold type and impingement of the PCL on arthroscopy.

SUBJECTS AND METHODS

Ninety-nine patients who underwent knee MRI and arthroscopy were included. All MRIs were retrospectively and independently assessed by 2 radiologists. Medial synovial folds of the PCL on MRI were categorized into 3 types. Type A showed no medial synovial fold. Type B showed a small synovial protrusion that did not extend beyond an imaginary line drawn from the medial tibial spine to the lateral aspect of the medial femoral condyle. Type C had a long enough fold to extend beyond the imaginary line. The presence of a tear in the anterior cruciate ligament, PCL, or menisci and impingement of the PCL were obtained from arthroscopic records.

RESULTS

Intraobserver agreement in the classification of medial synovial folds was nearly perfect (κ = 0.850). Interobserver agreement was substantial (κ = 0.759). Of 99 cases, 34 were type A, 41 were type B, and 24 were type C folds on MRI. Thirty-nine impingements of the PCL (39.4%) were identified on arthroscopy. Multivariable analysis revealed that type C folds were 40.60 times more likely to have impingement than type A folds (odds ratio, 40.60; 95% confidence interval, 8.73-188.93; P < 0.001).

CONCLUSIONS

Of the 3 types of medial synovial folds, type C was significantly associated with impingement of the PCL on arthroscopy. Therefore, type C folds may be a cause of internal derangement of the knee.