Chondromalacia Patellae

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Original Editors - Francky Petit

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Key Words

• Chondromalacia

1. Patellae
2. Therapy
3. Orthoses
4. Physiotherapy
5. Anatomy
6. Ice Application

• Chondropathie
• Patellofemoral Pain Syndrome

1. Therapy
2. Anatomy
3. Physiotherapy

• McConnell Tape
• Ice Application

Definition/Description

Chondromalacia patellae (CMP) is referred as anterior knee pain due to physical and biomechanical changes. It manifests as’ softening, swelling, fraying, and erosion of the hyaline cartilage overlying the patella and sclerosis of underlying bone’.
Simplified, it means that the articular cartilage o the posterior surface of the patella is going though softening and degenerative changes.
CMP is one of the main illnesses of “Patellofemoral pain syndrome" (PFPS)”, or is a synonym for PFPS (3A) and is also known as “Runner’s Knee”.

Clinically Relevant Anatomy

The knee exist of 4 major components/ bones: the femur, the tibia, the fibula and the patella. The femur has a trochlear groove which is

crucial for the patella because in this way it articulates with the femur. (5E) The articular cartilage, on the underside of the patella, provides the patella to glide over the femoral groove. This is necessary for an excellent motion in the knee joint. (5F) If there's pressure on the lateral side during turn, there will be a negative effect on the nutrition of the articular cartilage. More specifically in the medial and central area of the patella, where degenerative change will occur more readily. (5E)

On the patella inserts an important group of muscles: the quadriceps. The quadriceps femoris is divided into four different muscles with the same insertion on the patella: the rectus femoris (RF), the vastus lateralis (VL), the vastus intermedius (VI) and the vastus medialis (VM). The VM has oblique fibres , which is referred to the vastus medialis obliques (VMO)

These muscles are active stabilizers during knee extension, especially the VL (on the lateral side) and the VM (on the medial side). The VMO is active during knee extension but doesn't extend the knee. Its function is to keep the patella centered in the trochlea. This muscle is the only active stabilizer on the medial facet, so it's important to notice that the timing and amount of activity is critical to the patellofemoral function. Even the smallest changes will have significant effects on the position of the patella.
Not only the quadriceps will influence the patella position, but also the passive structures. “The passive structures are more extensive and stronger on the lateral side than they are on the medial side, with most of the lateral retinaculum arising from the iliotibial band (ITB). If the ITB is tight, excessive lateral tracing and/ or lateral patellar tilt can occur.” (5E)

Other anatomical structures we should pay attention to, are:

• The femoral anteversion (2C): or medial torsion of the femur is a condition which changes the
  
  alignment of the bones at the knee. This may lead to overuse injuries of the knee caused by malalignment of the femur in relation to the patella and tibia. (5E)
  
• The Q-angle: or 'quadriceps angle' can be defined as the geometric relationship between the pelvis, the tibia, the patella and the femur. (5E) (2C)
  
  

Epidemiology /Etiology

The etiology of CMP is poorly understood, although most authorities believe that the causes of chondromalacia are injury, generalized constitutional disturbance and patellofemoral contact, or a result of trauma to the chondrocytes in the articular cartilage (leading to proteolytic enzymatic digestion of the superficial matrix). Some authorities believe that chondromalacia is caused by instability or maltracking of the patella that softens the articular cartilage. (1B) Chondromalacia patella is usually described as an overload injury (overuse, misuse), caused by malalignment of the femur to the patella and the tibia. (5F)

Sometimes, a muscular imbalance between the VL en VM lies underneath. Weakness of the VM causes the patella to be pulled too far laterally. The patella will grind onto the condylus lateralis, which causes the degenerative disease.

Degenerative changes of the articular cartilage can be caused by (5F):

• Trauma: instability caused by a previous trauma or misuse during recovery
  
• Repetitive micro trauma and inflammatory conditions
  
• Postural distortion: causes malposition or dislocation of the patella in the trochlear groove
  

Some authors will use the term “patellar pain syndrome” instead of “chondromalacia” in order to describe “anterior knee pain”. (5E)

Stages of disease
In an early stage, chondromalacia shows areas of high sensitivity on fluid sequences. This can be associated with the increased thickness of the cartilage and may also cause oedema. In a later stage, there will be a more irregular surface with focal thinning that can expand to and expose the subchondral bone. (5E)
Chondromalacia patella is graded based on the basis of arthroscopic findings, the depth of cartilage thinning and associated subchondral bone changes. MRI is able to visualize this condition for moderate to severe forms. (5E)

• Stage 1: softening and swelling of the articular cartilage due to broken vertical collagenous fibres. The cartilage is spongy on arthroscopy.
  
• Stage 2: blister formation in the articular cartilage due to the separation of the superficial from the deep cartilaginous layers. Cartilaginous fissures affecting less than 1,3 cm2 in area with no extension to the subchondral bone.
  
• Stage 3: fissures ulceration, fragmentation, and fibrillation of cartilage extending to the subchondral bone but affecting less than 50% of the patellar articular surface.
  
• Stage 4: crater formation and eburnation of the exposed subchondral bone more than 50% of the patellar articular surface exposed, with sclerosis and erosions of the subchondral bone. Osteophyte formation also occurs at this stage.
  

Articular cartilage does not have any nerve endings, thus the CMP should not be considered as the true source of anterior knee pain. Actually chondromalacia is a pathological or surgical finding that represents areas of articular cartilage trauma or divergent loading. (5F)
In 2013, a retrospective review showed that there is significant association between subcutaneous knee fat thickness with the presence and severity of chondromalacia patellae. This could explain why women suffer more from the condition chondromalacia than men (Kok et al;, 2013). (2B)

Characteristics/Clinical Presentation

There are important distinguishing features between chondromalacia patellae and Osteoarthritis. But chondromalacia patellae affects just one side of the joint, the convex patellar side. (E) Excised patellas show localized softening and degeneration of the articular cartilage. (C) The main symptom of chondromalacia patellae is anterior knee pain. The pain is exacerbated by common daily activities that load the patellofemoral joint, such as running, stair climbing, squatting, kneeling, or changing from a sitting to a standing position (D). The pain often causes disability which affects short term participation as daily and physical activities. Other symptoms are tenderness when you palpate under the medial or lateral border of the patella (E); crepitation, this may be demonstrated with motion (B); minor swelling (E); a weak vastus medialis muscle, and a high Q-angle (E). The vastus medialis is functionally divided into two components: the vastus medialis longus (VML) and the vastus medialis obliquus (VMO). The VML extends the knee, with the rest of the quadriceps muscle. The VMO doesn’t extend the knee, but this muscle is also active throughout the knee extension. This component keeps the patella centered in the trochlea of the femur. (5E) The Q-angle is defined as the angle between the first line from the anterior superior iliac spine to the center of  the patella and the second line from the center of the patella to the tibial tuberosity (3B).
This condition fits within the general category of PFP (E) also causes a deficit in strength of the quadriceps muscle. Therefore, quadriceps strengthening exercises is often part of the revalidation plan. A significant number of individuals are asymptomatic, but crepitation in flexion or extension is mostly present. (E) Chondromalacia is common by adolescents and females. Idiopathic chondromalacia is mostly seen by young children and adolescents. Degenerative chondromalacia is common by middle-aged people and old age population. (5E)

Medical Management

If conservative measures fail, though, there are a number of possible surgical procedures. These procedures take place when the symptoms remain the same after the conservative measures. (5E)

The first option is called shaving, also known as chondrectomy. This treatment includes shaving down the damaged cartilage, just to the not-damaged cartilage underneath. The success of this treatment depends on the severity of the cartilage damage.
Drilling is also a method that is frequently used to heal the damaged cartilage. However, this procedure has not so far been proved to be effective. More localized degeneration might respond better to drilling small holes through the damaged cartilage. This facilitates the growth of the healthy tissue through the holes, from the layers underneath.

The most severe surgical treatment is a full patellectomy. This operation is only used when no other procedures were helpful. A big consequence is that the quadriceps will weaken very hard. Two potential treatments may be successful: (5F)

• Replacement of the damaged cartilage : The damaged cartilage is replaced by a polyethylene cap prosthesis. Early results have been good, but eventual wearing of the opposing articular surface is inevitable.
  
• Autologous chondrocyte transplantation under a tibial periosteal patch. (5F)
  

Simply removing the cartilage is not enough to cure chondromalacia patellae. The biomechanical problem needs addressing and there are various procedures to aid re-alignment :
1. Thightening of the medial capsule (MC) : If the MC is lax, it can be tightened by pulling the patella back into its correct alignment.
2. Lateral release : A very tight lateral capsule will pull the patella laterally. Release of the lateral patellar retinaculum allows the patella to track correctly into the femoral groove.
3. Medial shift of the tibial tubercle : Moving the insertion of the quadriceps tendon medially at the tibial tubercle, allows the quadriceps to pull the patella more directly. It decreases also the amount of wear on the underside of the patella.
4.Removal of a portion of the patella

Although there is no agreement of the treatment of chondromalacia, there is a general consensus that the best treatment is a non-surgical one.

Physical Therapy Management

Tests:

First of all the hardest task for the physiotherapist is to ascertain the disease. At first it is necessary to inspect the position and posture of the patient. Look at eventual asymmetries, like the limb alignment in standing, internal femoral rotation, anterior or posterior pelvic tilt, hyperextended or ‘locked back’ knees, genu varum or valgum and abnormal pronation of the foot. When there are asymmetries or abnormal positions in one of these anatomic structures, it will affect the patients gait pattern. (5E)

Next you have to test the mobility / range of motion (ROM) of the joint. With chondromalacia there is very often a limitation in the ROM. When there is a bursitis present, a passive flexion or active extension will be painful. You can also test the isometric power of the muscles, here especially the quadriceps. The affected leg will show a loss of power, according to the non-injured leg. There are also some specific test to diagnose anterior knee pain syndrome, of which CMP is a part: (5)

• Patellar-grind test a.k.a. Clarke’s sign
  
• Compression tes
  
• Extension-resistance test
  
  

Note that it is still possible to diagnose wrong, these test may help in determine chondromalacia but it is best to rule out other diagnoses. (3A)

Exercise Program:

The most common way to treat chondromalacia patellae is by strengthening the quadriceps muscle, because it has a very significant role in the movement of the patella. Stretching of the vastus lateralis and strengthening of the vastus medialis is often recommended, but they are difficult to isolate because they have the same innervation and insertion. Therefore, it’s easier to strengthen the whole quadriceps.

In this aspect of the therapy, make sure to give strength exercises, resistance exercises and coordination exercises of the quadriceps. Here is an example of an exercise program:

Coordination Exercises

1. Sit with the IL on a rolled towel under the fossa popliteum with no weight on the leg.
   1.JPG
   
   Extend the leg fast an relax slowly 50x
   
   
   
2. stand on one leg (IL) with the knee slightly bent. Tap the foot of the HL
   2.JPG
   
   in front, left, right and behind you on the floor
   
   
   
3. Jumping: from left to right, from the back to the front, in a square and
   3.JPG
   in a diamond.

Strength Exercises

1. Extend the IL for 10 seconds.
   4.JPG
   
   
   
   
   
2. Make a big step with the IL in front. You can make the exercise harder by
   5.JPG
   
   raising the distance, bending the knee moreand by jumping on the IL.
   

Resistance Exercises

1. sit at the front of a chair with both legs extended just above the floor.
   6.JPG
   
   Push the heel of the healthy leg(HL) against the heel of the injured leg(IL).
   Make sure there is no movement in both legs. Hold for 7 seconds.
   
   
   
2. Sit with the IL on a rolled towel under the fossa popliteum,
   7.JPG
   
   with a weight on the leg
   
   
   
3. stand with the IL, slightly bent, in front of the extended HL. Bend the IL
   8.JPG
   
   slowly. Make sure the knee never passes the foot. Move your
   weight to the IL. When you feel pain, quit immediately.
   
   
4. stand with the IL on a step. Touch with the HL the floor by bending the
   9.JPG
   
   IL, first with the toes, then with the foot, then with the heel of the foot.
   

Not only do you have to strengthen the quadriceps, stretching is also an important. And hereby you can also stretch the hamstrings and the iliotibial band. (5F) It is proven that patients with patellofemoral pain syndrome have shorter hamstrings than asymptomatic controls. Also are their hamstrings less flexible. It is recommended to stretch this tissues because it seems to improve the flexibility and knee function. Though it doesn’t improve pain or function by stretching alone. Including stretching in the therapy, in addition to active treatments, gives positive outcomes. (1A)

Ice & Drugs:

Ice is sure to decrease pain, but is more frequently used to treat acute injuries. The efficacy of ice is questioned and the exact effect isn’t clear too. Therefore, more studies are required to create evidence based guidelines.
The benefit of anti-inflammatory drugs (NSAID’s) has not yet been proved. Although a lot of treatments for CMP aren’t proved either, the potential side effects of NSAID’s may be more severe than the side effects of ice and exercise. Therefore, a judicious trail may be worthwile.

Tapies and braces:

Taping the patella into a certain position may be helpful, but the scientific evidence is varied. A commonly used technique is the ‘McConnell taping’. When taped properly, the McConnell tape may have a short-term pain relief.

Every form of supporting the patella and knee joint has proven that it can possibly reduce pain and symptoms but it is also possible it will change the tracking of the patella. Though it can be helpful because during the rehabilitation, patients will avoid certain movements to reduce the pain. This can cause a less functioning of the quadriceps. So using a brace or every form of support, that relieves the patient from pain, may aid in the recovery, as they will dare to use their quadriceps. This can be used for patients preoperatively as well as postoperatively. However there is suggested to use a brace which allows variation in the medial patellar pull and pressure.

Foot Orthoses

Foot orthoses may be helpful in the pain relief of the knee, but only if the patient has signs of an excessive foot pronation, or a lower extremity alignment profile that includes excessive lower extremity internal rotation during weight bearing and increased Q-angle at the same time as he suffers from chondromalacia. When made properly, the orthotics will cause biomechanical changes (for example: a reduction in the Q-angle and internal rotation) in the lower leg by preventing overpronation in pes planus and providing a better support for normal feet and Pes cavus. (5E)