Introduction:

Chondromalacia (runner's knee) is the affliction of hyaline cartilage coating of the articular surface of the bone. Most commonly it is recognized as involving the extensor mechanism of the knee and accordingly is often referred to as Chondromalacia of the patellae, patellofemoral syndrome or runner's knee. Chondromalacia patellae is referred to as anterior knee pain due to physical and biochemical changes. The articular cartilage of the posterior surface of the patellae is going through degenerative changes which manifest as softening, swelling, fraying and erosion of hyaline cartilage underlying the patellae and the underlying bone.

Prevalence: More women than men are affected. There does not appear a hormonal cause of variation. Active young adults who participate in running sports and workers who increase stress in their patellofemoral joint by repeated stair climbing and/ or kneeling have higher incidence of chondromalacia.

Causes: It is believed that the causes of chondromalacia are:

·       Injury

·       Generalized constitutional disturbance and patellofemoral contact.

·       Or as a result of trauma to chondrocytes in the articular cartilage (Leading to proteolytic enzymatic digestion of the superficial matrix.

·       Instability or malt racking of patellae which softens the articular cartilage.

·       Chondromalacia patellae, an overload injury is caused by malalignment of the femur to patellae and tibia.

Clinical presentation:

·       Chondromalacia patellae (CMP) affects just one side of the joint, the convex patellar side with excised patella’s show localized softening and degeneration of articular disc.

·       The main symptom of CMP is anterior knee pain, which is exacerbated by common daily activities that load the patellofemoral joint such as running, stair climbing, squatting, kneeling, or changing from a standing to sitting position.

·       The pain often caused the disability affecting the short-term participation of daily and physical activities.

·       Tenderness on palpitation on the medical and lateral border of patella

·       Crepitations felt on motion.

·       Minor swelling.

·       A weak vastus medialis muscle and a high Q angle which leads to weakness in quadriceps. Therefore, quadricep strengthening is essential.

Differential diagnosis:

·       Patellar subluxation

·       Osteoarthritis

·       Rheumatoid arthritis

·       Anterior knee pain

·       Patellofemoral pain syndrome.

Diagnosis:

Examination; Examination of knee is 4-fold;

·       Observation: joint appearance is usually normal but there appears to be slight effusion.

·       Mobility: passive movements are usually painless and free, but repeated extension of knee from flexion will produce pain and a grating feeling underneath the patella, especially if the articular surfaces are compressed together.

·       Feel: pain and crepitus will be felt if the patellae is compressed against the femur, either vertically or horizontally, with the knee in full extension. By displacing the patellae medially or laterally, the patellar margins and their articular surfaces may be felt. Resisting a static quadriceps contraction will generally produce a sharp pain under the patella.

·       X-rays: In most of the cases there is no convincing radiological change. In the later stages, patellofemoral joint space narrows and osteoarthritic changes begin to appear.

Tests: There are specific tests for anterior knee pain syndrome;

·       Patellar grind test or Clark’s sign – The test detects the presence of patellofemoral joint disorder. A positive sign on this test is pain in patellofemoral joint.

·       Extension- resistance test – This test is used to provide a maximal provocation on the muscle-tendon mechanism of the extensor muscles and is positive when the affected knee demonstrates less power when trying to maintain pressure.

·       Compression test

·       The critical test – This is done in patient with high sitting and performing isometric quadriceps contractions at 5 different angles (0°,30°,60°, 90°, and 120°) while the femur is externally rotated, sustaining the contractions for 10 seconds. If pain is produced then the leg is positioned in full extension. The lower leg of the patient is supported by therapist so that the quadriceps can be fully relaxed. When the quadriceps is relaxed, the therapist bus able to glide the patellae medially. This glide is maintained while the isometric contractions are again performed. If this reduces the pain and the pain is of patellofemoral in origin, then there is high chance of favorable outcome.

Management:

1.    Surgical intervention:

·       Cordectomy also known as shaving, includes shaving done in damaged cartilage to the non-damaged cartilage underneath.

·       Drilling- more localized degeneration might respond better to drilling small holes through the damaged cartilage. This facilitates the growth of healthy tissue through the holes from the layers underneath.

·       Full patellectomy – most severe surgical treatment, it’s only used when no other procedures were helpful, but a significant consequence is the weakening if quadriceps.

·       Other treatments that may be successful are replacement of the damaged cartilage and autologous chondrocyte transplantation.

 

2.    Physical therapy management:

·       Exercise program –

- Isometric quadriceps strengthening and stretching exercises.

- Hamstring stretching exercise

- Temporary modification of activity

-  Patellar taping

-  Foot orthoses

-Hip strength and stability training

-  Hip abductor strengthening

-  Patellar realignment brace.

 

·       Ice medication - may be used for reducing pain in an acute flare-up, but not as a long-term treatment protocol.

·       Taping and braces- Taping if patella is done to influence bits movement. It may provide short term relief.

·       Supporting the patella and the knee joint by bracing is a further way to reduce pain and symptoms, but will alter patella tracking and reduce active function of quadriceps. Bracing may be useful in short term to offer patients some support and pain relief.

·       Foot orthosis – used only in cases where lower limb mechanics are expected to contribute to knee pain, which may be due to

-          Poor pronation control.

-          Excessive lower limb internal rotation during weight-bearing.

-          An increased Q angles.

·       Foam roller – It is useful for relieving tight musculature and reducing pressure over patella.

References:

·       Handbook of Physical Medicine and Rehabilitation, 2nd edition, Susan J. Garisson

·       Kisner, kolby 2007,Apr., therupatic exercise.