Degenerative vs traumatic
Lateral Meniscus
There seems to be uncertainty in my medical notes as to whether the lateral meniscus tear was degenerative or traumatic. This must be expected since the fellows don't actually know what happened. I was asked what was the main problem, so I started with the pain in the lateral side of my knee...
After the arthroscopy, there seems to be confusion as to whether the damage that was found was degenerative, that's damage that resulted in either, or both:
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a radial tear in the lateral meniscus,
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chondromalacia of the patella in the medial compartment.
Cartilage cracking, fragmentation and erosion over time has resulted in full-thickness loss of your weight-bearing (articular) cartilage, often altering the alignment of your lower extremity towards bowing (bow-legged). This condition is osteoarthritic in nature.
http://www.healthline.com/health/chondromalacia-patella#Diagnosis&Grading5:
Grade IV, the most severe grade, indicates exposure of the bone with a significant portion of cartilage deteriorated. Bone exposure means bone-to-bone rubbing is likely occurring in the knee.
I know that the injury to my lateral meniscus was traumatic because it happened when I was jogging. I was told that the violent, violent, violent pain that I felt in the lateral side of my knee was very likely my lateral meniscus tearing.
In athletes, a meniscus tear usually is a traumatic origin. They result or abnormally high forces that fail the substance of the meniscus. While these are often the result of forceful twisting or pivoting movements, they can also occur with seemingly innocuous activities such as squatting or jogging...
In older patients, a meniscus tear may not be of traumatic origin but rather part of degenerative changes in the knee. These tears are often accompanied by some arthritic changes in the knee and are referred to as “degenerative” tears.
And the fact that the tear was 'radial' is also suggestive of a traumatic origin. However, the injury had happened about 7½ years before the arthroscopy. So it may be likely that degenerative processes have been underway in the mean time. But this should not distract from assessing the injury as that of 'trauma', despite my age.
http://www.orthop.washington.edu/?q=patient-care/articles/sports/torn-meniscus.html
Degenerative meniscal tears are thought to occur as part of the aging process when the collagen fibers within the meniscus start to break down and lend less support to the structure of the menicus. Degenerative tears are usually horizontal in the meniscus producing both an upper and lower segment of meniscus. These segments usually don't move out of place and therefore are less likely to produce mechanical symptoms of catching or locking. Traumatic meniscal tears are usually radial or vertical in the meniscus and are more likely to produce a moveable fragment that can catch in the knee and therefore require surgical treatment...
Most traumatic meniscal tears occur as a result of a twisting injury when the knee rotates but the foot stays fixed in position. The meniscus can also tear from extreme bending of the knee. The combination of bend, rotation, and sudden kick that occurs in some forms of martial arts is associated with lateral meniscal tears.
"... a result of a twisting injury when the knee rotates but the foot stays fixed in position..."
The most common cause is abnormal “wear and tear” of the weight-bearing (articular) cartilage layer within the medial (inner) weight-bearing compartment exposing bare bone. This may have evolved from an unrecognized, high-impact injury, excessive weight or prolonged weight-bearing on hard surfaces. It often results after injury or loss of the shock-absorbing fibrocartilage (meniscus) within the inner (medial) compartment.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3781854/
(2010)
The main functions of the menisci are tibiofemoral load transmission, shock absorption, lubrication of the knee joint,17–21 and congruity improvement between the femoral and tibial articular surfaces in all knee flexion and rotation angles, since the menisci follow the motion of the opposing joint surfaces.1,22 30%–55% of the load in a standing position is transmitted by the knee menisci.19 Meniscectomy may determine decrease in contact area up to 50%–70%. The resulting increase in contact stresses on the tibial plateau are regarded as the main reason for the frequent bone and cartilage changes found after meniscectomy.1,23
So what happened?
The PMTL [Popliteus muscle-tendon-ligament unit] is made up of the popliteus muscle, the popliteofibular ligament (PFL), the femoral insertion of the popliteus tendon, the popliteomeniscal fascicles and soft tissue attachments to the lateral meniscus, and the proximal tibia...
The popliteus tendon and PFL are the most important elements of this unit in terms of providing stability to the knee. These structures aid the FCL and posterolateral capsule to prevent excessive external tibial rotation and varus rotation. [That is, they keep the bones stable in that corner of the knee.]...
The popliteus muscle originates at the back of the tibia and proceeds around the side and up (lateral and proximal) to insert on the lateral femoral condyle. Its tendon proceeds on proximally through a gap in the coronary ligament of the lateral meniscus, then passes deep to the FCL to ultimately insert in front of and below (anterior and distal) to the insertion of the FCL.
The PFL originates at the musculotendinous junction of the popliteus and attaches to the medialaspect of the fibular head, where it lies deep to the fabellofibular ligament.
(2008)
Biomechanically, the combined structures of the PLC have greater tensile strength than any of the other major knee ligaments and are subjected to significant tensile forces during normal gait (Figure ). The PLC acts in concert with the PCL in providing stability by resisting posterior translation and external and varus rotation of the tibia on the femur. 4,14 The PLC serves as the primary restraint to both varus and external rotation forces, with the PCL acting as a secondary restraint.1,15–17 The LCL plays the greatest role in resisting varus stress, while the other components of the PLC play a larger role in resisting external rotation of the lateral side of the tibia on the femur. The popliteus and popliteofibular ligament, in particular, have been shown to be the most important structures in resisting external rotation. 11,15,16,18–21 Therefore, repair or reconstruction of the PLC typically attempts to recreate the LCL for varus stability and the popliteus and/or popliteofibular ligament for stability in external rotation (Figure ). The PLC also acts as a restraint to posterior translation of the tibia on the femur, secondary to the PCL. Therefore, disruption of the PLC with an intact PCL results in increased varus and external rotation of the knee, most pronounced at 30° of knee flexion, while disruption of the PCL with an intact PLC results in increased posterior translation of the tibia, most pronounced at 90° of knee flexion. Disruption of both the PLC and PCL causes increased varus angulation, external rotation, and posterior translation at all angles of knee flexion. 1,14 PLC and PCL disruption also increases medial, lateral, and patellofemoral compartment pressures that can lead to early degenerative joint disease in these compartments if the biomechanical integrity of these structures is not restored.
I find this difficult to read because PCL, posterior cruciate ligament, and PLC, posterolateral corner, are very similar. So when I read it I insert the words 'ligament' and 'corner' where appropriate and break down the content into smaller sections:
The corner ... acts as a restraint to posterior translation of the tibia on the femur, secondary to the ligament.
Therefore, disruption of the corner with an intact ligament results in increased varus and external rotation of the knee, most pronounced at 30° of knee flexion,
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increased varus angulation,
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external rotation most pronounced at 30° of knee flexion.
while disruption of the ligament with an intact corner results in increased posterior translation of the tibia, most pronounced at 90° of knee flexion.
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increased posterior translation of the tibia most pronounced at 90° of knee flexion.
Disruption of both the corner and ligament causes increased varus angulation, external rotation, and posterior translation at all angles of knee flexion.
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increased varus angulation,
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external rotation,
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posterior translation at all angles of knee flexion.
Corner and ligament disruption also increases medial, lateral, and patellofemoral compartment pressures that can lead to early degenerative joint disease in these compartments if the biomechanical integrity of these structures is not restored.
Questions:
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My LCL is intact...???
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My PCL is intact...???
So... xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Chondromalacia
The following quote is taken from a Q&A forum, and this answer clearly explains Grade 4 chondromalacia as being just before getting bone on bone contact:
http://www.kneeguru.co.uk/KNEEtalk/index.php?topic=25194.0
Chondromalacia actually means a thinning of the articular cartilege. This is the tough cartilege that coves the ends of the bones, not the meniscus (which is what most people think of when they say "cartilege"). Chondromalacia is graded in four steps, with I being mild (showing some softening) and IV being the worst before getting right to bone on bone. There is no way to "cure" the defects, but you can hope to stop the degeneration.
The question is why do you have chondromalacia? It isn't really a diagnosis in itself. In fact, different doctors use it to mean different things. If I were you, I'd try to get the OS to give you more details about your condition. You won't be able to stop the degeneration unless you know what is causing it in the first place.
http://www.wheelessonline.com/ortho/chondromalacia_of_the_patella
Chondromalacia of the Patella
- Clinical Features and Exam:
- pts may report anterior knee pain, esp. while climbing stairs;
- compression of patella may cause pain along medial & lateral retinacula & patellar ligament;
- compression of the patella during flexion & extension of knee may elicits crepitation and discomfort;
- patellar tracking
- best seen when examiner is seated in front of pt & takes knee through full passive and active ROM.
- crepitus:
- may be a normal finding in young people;
- misc signs:
- excessive tibial rotation
- foot pronation
Fig
Diagram of different types of meniscal tears, taken from http://www.drallenfanderson.com/knee/meniscal-injuries
Fig
Table showing some structures of the posterolateral corner and the function that they fulfil.