Anterior Cruciate Ligament (ACL) Mucoid Degeneration
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Anterior Cruciate Ligament Mucoid Degeneration[edit | edit source]
Anterior Cruciate Ligament is an important structure of the knee joint. Anatomically, it is arranged in a crossed pattern to the Posterior Cruciate Ligament, therefore, it is also known as cruciform ligament. The ligament conists of two fibers, mainly, the anterio-medial and postero-lateral fibers, respectively.The cruciate ligament have mechanoreceptors, which are responsible to detect any change in position of the knee, direction, speed and tension. The ligament is mainly responsible for restraning anterior translation of knee. Along with that, it also controls the internal rotation. Therefore, Anterior Cruciate Ligament tear is more susceptible during any injury to the knee.
What is Anterior Cruciate Ligament Mucoid Degeneration?[edit | edit source]
This is a rare pathological condition, in which there is increased signal from within the ligament. Mucoid degeneration, is irreversible degeneration of the tissue with the infiltration of mucin within the fibers[1]. Multiple theories have been put forth that explains the pathological disorganisation in the collagen fibers of the Anterior Cruciate Ligament, such as synovial, traumatic, and degenerative,“Synovial” theory- states that there is accumulation of synovial fluid inside the substance of ACL in a herniated pouch of synovium.“Traumatic” theory - post injury, ACL fibroblasts secrete glycosaminoglycans, the mucin substance within the ACL. Other theories include “Degenerative” theory- MD could occur due to ageing.[2]
Clinical Findings[edit | edit source]
No extension block[2]
Joint line tenderness[2]
Painful terminal knee flexion[3]
Stiffness[3]
Posterior knee pain
No instability[3]
Causes[edit | edit source]
Trauma
Ageing
Primary condition- Osteoarthritis
Complications[edit | edit source]
Impingement
Ganglionic cyst
Tendon tear/ Tendon rupture
Radiological Findings[edit | edit source]
ULTRASOUND:[edit | edit source]
Hypoechoic foci are seen,within the fibrillar architecture of tendons or ligaments.
ARTHROSCOPY:[edit | edit source]
Arthroscopically ACL is intact but fibrillated, yellowish and hypertrophied, with interspersed yellowish mucinous material along the fibers, lack of synovial linning of the ACL and absent ligamentum mucosum.
MRI:[edit | edit source]
Characteristic:"celery stalk" appearance.
Ligaments and tendons affected by mucoid change might display a thickened and/or ill-defined appearance characterized by nonspecific linear or globular increase in signal intensity.
It is mislead as ACL tear on MRI findings, hence requires probing and histopathology for definitive diagnosis.
Differential Diagnosis[edit | edit source]
Conditions that resembles the clinical findings are:
- Ligament tear
- Ligament rupture
- Fatty infiltration
- Ligament sprain
- Ganglion cyst
Treatment[edit | edit source]
References[edit | edit source]
- ↑ Palmer, W., Bancroft, L., Bonar, F. et al. Glossary of terms for musculoskeletal radiology. Skeletal Radiol 49, 1–33 (2020). https://doi.org/10.1007/s00256-020-03465-1
- ↑ 2.0 2.1 2.2 Pandey, Vivek et al. “Mucoid degeneration of the anterior cruciate ligament: Management and outcome.” Indian journal of orthopaedics vol. 48,2 (2014): 197-202. doi:10.4103/0019-5413.128765
- ↑ 3.0 3.1 3.2 Khalid Ibn el Kadi et al. Mucoid degeneration of the anterior cruciate ligament: a case report. Pan African Medical Journal. 2013;15:59. [doi: 10.11604/pamj.2013.15.59.2534]
