Summary

Chondromalacia Patellae (literally "Soft Cartilage of the Kneecap") is the pathological softening of the articular cartilage on the undersurface of the patella. It is the end-stage finding of Patellofemoral Pain Syndrome (PFPS). The root cause is usually Maltracking: the patella is pulled laterally by a tight IT Band/Retinaculum and a weak VMO (Vastus Medialis Obliquus). This causes it to grind against the lateral femoral condyle instead of gliding centrally in the trochlear groove. Management is overwhelmingly conservative (Physiotherapy). [1,2,3]

Key Facts

• The "Movie-goer's Sign" (Theatre Sign): Pain after sitting for a long time with knees bent. This position compresses the patella into the femur (Patellofemoral Joint Reaction Force). Extension relieves it.
• The "J Sign": As the patient extends the knee from 90° to 0°, the patella "jumps" laterally at the end (forming an inverted J shape).
• Q-Angle: Increased Q-angle (Valgus knees, wide hips) increases the lateral vector force on the patella.

Clinical Pearls

"Don't Squat Deep": Patellofemoral contact pressure skyrockets past 30-45 degrees of flexion. Rehab should be "Short Arc Quads" (0-30 degrees) to build muscle without grinding the bone.

"It's a Track Problem, not a Train Problem": The problem is rarely the patella itself (the train), but the alignment of the hips and feet (the track). Weak Gluteus Medius causes internal femoral rotation -> apparent lateral patella tracking.

"Stairs are Hell": Going DOWN stairs is worse than going UP (Eccentric load on quads maximizes comprehensive force).

                 ANTERIOR KNEE PAIN
                        ↓
                  HISTORY & EXAM
            (Exclude Meniscus / Tendon)
                        ↓
              PFPS / CHONDROMALACIA
                        ↓
             CONSERVATIVE (The Mainstay)
           ┌────────────┼─────────────┐
        ACTIVITY      PHYSIO        TAPING
       (No Squats)  (VMO/Glutes)  (McConnell)
                        ↓
                  3-6 MONTHS FAIL?
                        ↓
             IMAGING (MRI / CT Protocol)
             (Check Trochlear Dysplasia)
                        ↓
                     SURGERY
             (Lateral Release / TTO)

1. Physiotherapy (Gold Standard)

• VMO Strengthening: Straight Leg Raises, Short Arc Quads. (Avoid deep squats).
• Gluteal Strengthening: Clamshells. (Controls femoral rotation).
• Stretching: IT Band and Hamstrings.
• Taping: McConnell Taping pulls the patella medially to offload the lateral facet during exercise.

2. Surgical (Last Resort)

• Lateral Retinacular Release: Cutting the tight lateral tissue. (Only if tight tilt demonstrated).
• Tibial Tubercle Osteotomy (Fulkerson): Moving the tibial insertion Medially (to correct Q-angle) and Anteriorly (to offload the joint).
• MPFL Reconstruction: If frank instability/dislocation is the issue.

The Heintjes Review (Cochrane)

• Exercise therapy reduces pain and improves function in PFPS.
• Combined hip (gluteal) and knee (quads) exercises are superior to knee exercises alone.

Lateral Release Controversy

• Lateral release was once common. It is now rarely done in isolation as it can lead to medial instability (iatrogenic dislocation) and doesn't fix the underlying Q-angle.

The Train Track Analogy

The kneecap (Train) runs in a groove on the thigh bone (Track). The muscles are the ropes pulling the train. If the outer rope (Thigh muscle) is tight and the inner rope (VMO) is weak, the train gets pulled off the tracks and grinds against the side rail.

Why does it hurt to sit?

When you bend your knee, the kneecap gets pressed hard against the thigh bone. If the cartilage is soft/bruised, this constant pressure causes an ache. Straightening the leg takes the pressure off.

Will Physiotherapy work?

Yes, but it takes time (3-6 months). We need to build the inner muscle (VMO) big enough to pull the kneecap back into the center of the groove.

Q1: What is the Q-Angle? A: The Quadriceps Angle. Drawn from ASIS to Patella Centre, and from Patella Centre to Tibial Tuberosity. Normal is 14° (Men) and 17° (Women). An increased Q-angle creates a lateral vector force on the patella, predisposing to maltracking and dislocation.

Q2: Describe Clarke's Test and why it is controversial. A: The examiner presses the patella distally while the patient contracts the quadriceps. This grinds the articular surfaces together. Positive = sharp pain. It is controversial because it is painful even in normal knees (high false positive) and distressing to the patient.

Q3: What exercises should be avoided in Chondromalacia? A: Open Kinetic Chain extension (e.g., Leg Extension Machine) from 90 to 0 degrees, and Deep Squats (>60 degrees). Both generate massive patellofemoral reaction forces (up to 7x body weight). Rehab focuses on Closed Kinetic Chain in safe ranges (0-30°).

(End of Topic)