{"id":11587,"date":"2025-05-09T06:00:04","date_gmt":"2025-05-09T05:00:04","guid":{"rendered":"https:\/\/blogs.bmj.com\/bjsm\/?p=11587"},"modified":"2025-05-08T12:40:55","modified_gmt":"2025-05-08T11:40:55","slug":"the-msk-playbook-chondromalacia-part-1","status":"publish","type":"post","link":"https:\/\/blogs.bmj.com\/bjsm\/2025\/05\/09\/the-msk-playbook-chondromalacia-part-1\/","title":{"rendered":"The MSK Playbook: Chondromalacia Part 1"},"content":{"rendered":"

Introduction<\/span><\/h3>\n

Anterior knee pain or \u201crunner\u2019s knee\u201d is a common presenting complaint in the MSK clinic. In active individuals, progressive overload of the patellofemoral joint, and disruption of the under surface of the hyaline cartilage of the kneecap, can cause significant disability, pain and impact training. We discuss the key risk factors for chondromalacia, the sports and biomechanical risk factors, imaging findings and the latest cartilage therapies to preserve and treat this condition.<\/span><\/p>\n

The knee consists of the patellofemoral joint and medial and lateral tibiofemoral joint. Though chondromalacia can also occur in joints such as the hip and shoulder, damage to the cartilage located on the posterior aspect of the patella that articulates with the trochlear groove of the femur, is the most common manifestation of the condition in MSK clinics (1).\u00a0<\/span><\/p>\n

Figure 1: Diagram of the knee joint<\/strong><\/p>\n

\"\"<\/p>\n

Chondromalacia patella is a <\/span>radiological finding (2).<\/span> It sits on a spectrum from normal physiological loading to positions where the kneecap is unstable or misaligned. <\/span>The challenge for MSK clinicians is to work up the patient, understand why the radiological changes have occurred and treat the reversible biomechanical, structural and ortho biological risk factors.\u00a0<\/span><\/p>\n

Presentation pattern<\/span><\/h3>\n

Patients usually present with symptoms after undertaking exercises that increase joint loading forces at the patella. These typically include ascending or descending stairs, squatting or running that cause (1, 3):<\/span><\/p>\n

    \n
  • Anterior knee pain<\/span><\/li>\n
  • Gradual onset of vague, non-specific retro patellar or prepatellar pain<\/span><\/li>\n
  • Retro patellar crepitus, effusion or wasting of quadriceps (<\/span>4)<\/span><\/li>\n<\/ul>\n

    It is important to remember that chondromalacia patella rarely occurs by itself and sits along a spectrum of other tendon and soft tissue conditions that cause patellofemoral pain syndrome (PFPS) or \u201crunner\u2019s knee\u201d (5).<\/span><\/p>\n

    Who is affected?<\/span><\/h3>\n
      \n
    1. Women are disproportionately affected<\/b>: The Q angle is the angle formed between the lateral line of the pull of the quadriceps and the patella, measured from the centre of the anterior superior iliac spine (ASIS) to the tibial tuberosity. The average Q angle for men is 14 degrees, and 17 in women, due to a broader pelvis. A higher mean Q angle value is said to contribute to patellofemoral pain (<\/span>6). <\/span>\u00a0<\/span><\/li>\n
    2. Active young adults: <\/b>Those engaged in running sports or individuals who frequently subject their patellofemoral joints to stress through repetitive stair climbing or kneeling are at a higher risk for developing chondromalacia. <\/span><\/li>\n<\/ol>\n

      Figure 2: Diagrammatic representation of the Q angle with respect to the patella and ASIS<\/strong>
      \"\"
      <\/p>\n

      Diagnostic difficulties<\/span><\/h3>\n
        \n
      • Determining the exact prevalence of chondromalacia is challenging due to its overlap with patellofemoral joint syndrome, variations in diagnostic criteria, and that it is rarely seen alone without other pathology.<\/span><\/li>\n
      • A recent systematic review estimated that the annual prevalence of patellofemoral pain in the general population is approximately 22.7%, rising to 28.9% among adolescents (7).<\/span><\/li>\n
      • In the general population, the prevalence of chondromalacia can be as high as 36.2%, with rates reaching up to 50% in middle-aged individuals between 30 and 40 years of age (8).<\/span><\/li>\n<\/ul>\n

        Figure 3: Risk factors associated with chondromalacia patella<\/b><\/p>\n

        \"\"

        Risk factors<\/h3>\n

        Table 1: Risk factors for chondromalacia patella<\/b><\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
        Category<\/b><\/td>\nRisk Factor<\/b><\/td>\nDescription<\/b><\/td>\n<\/tr>\n
        Intrinsic Factors<\/b><\/td>\nBiomechanical Alignment Issues<\/b><\/td>\n\u00a0<\/b><\/td>\n<\/tr>\n
        \u00a0<\/b><\/td>\nPatellar Malalignment<\/span><\/td>\nMisalignment of the patella in the femoral groove increasing stress on the cartilage<\/span><\/td>\n<\/tr>\n
        \u00a0<\/b><\/td>\nQ-Angle<\/span><\/td>\nAn increased Q-angle predisposing individuals to patellar tracking problems\u00a0<\/span><\/td>\n<\/tr>\n
        \u00a0<\/b><\/td>\nRotational malalignment of lower limbs<\/span><\/td>\nConditions leading to improper alignment and movement patterns, putting extra stress on the knee joint – including femoral anteversion or tibial torsion, flat feet or overpronation<\/span><\/td>\n<\/tr>\n
        \u00a0<\/b><\/td>\nValgus alignment<\/span><\/td>\nThe misalignment shifts load disproportionately onto certain areas of the knee cartilage, increasing wear and tear. Over time, this uneven stress can lead to softening and breakdown of the cartilage, as the patella may not track smoothly<\/span><\/td>\n<\/tr>\n
        <\/td>\nRotational malrotation of lower limbs<\/span><\/td>\nExcessive internal or external rotation of the femur or tibia disrupts normal knee mechanics and patellar tracking, causing the patella to move unevenly within the trochlear groove.<\/span><\/td>\n<\/tr>\n
        <\/td>\nTrochlear dysplasia<\/span><\/td>\nCauses patellar instability. This instability leads to uneven pressure, abnormal shear forces, and repeated trauma on the cartilage, wearing it down over time.<\/span><\/td>\n<\/tr>\n
        <\/td>\nMuscle Imbalances<\/b><\/td>\n\u00a0<\/span><\/td>\n<\/tr>\n
        <\/td>\nGluteal Weakness<\/span><\/td>\nPredisposes to relying excessively on the tensor fasciae late (TFL) which pulls on the iliotibial band (ITB) causing lateral maltracking of the patella<\/span><\/td>\n<\/tr>\n
        \u00a0<\/b><\/td>\nQuadriceps Weakness<\/span><\/td>\nWeakness, particularly in the vastus medialis obliquus (VMO), resulting in poor patellar tracking<\/span><\/td>\n<\/tr>\n
        \u00a0<\/b><\/td>\nTight Hamstrings or Iliotibial (IT) Band<\/span><\/td>\nTightness in these areas altering knee mechanics and increasing patellofemoral joint stress<\/span><\/td>\n<\/tr>\n
        \u00a0<\/b><\/td>\n\u00a0<\/span><\/td>\n\u00a0<\/span><\/td>\n<\/tr>\n
        \u00a0<\/b><\/td>\nPrevious Knee Injuries<\/b><\/td>\n\u00a0<\/b><\/td>\n<\/tr>\n
        \u00a0<\/b><\/td>\nHistory of Knee Injuries<\/span><\/td>\nInjuries such as fractures, ligament tears, or dislocations contributing to abnormal patellar movement<\/span><\/td>\n<\/tr>\n
        \u00a0<\/b><\/td>\n\u00a0<\/span><\/td>\n\u00a0<\/span><\/td>\n<\/tr>\n
        \u00a0<\/b><\/td>\nAge and Gender<\/b><\/td>\n\u00a0<\/b><\/td>\n<\/tr>\n
        \u00a0<\/b><\/td>\nAdolescents and Young Adults<\/span><\/td>\nMore commonly affected, particularly those active in sports<\/span><\/td>\n<\/tr>\n
        \u00a0<\/b><\/td>\nFemales<\/span><\/td>\nHigher risk due to wider pelvis and larger Q-angle<\/span><\/td>\n<\/tr>\n
        \u00a0<\/b><\/td>\n\u00a0<\/b><\/td>\n\u00a0<\/b><\/td>\n<\/tr>\n
        Extrinsic Factors<\/b><\/td>\nPhysical Activity<\/b><\/td>\n\u00a0<\/b><\/td>\n<\/tr>\n
        \u00a0<\/span><\/td>\nRepetitive Stress<\/span><\/td>\nHigh-impact sports or activities involving repetitive knee bending<\/span><\/td>\n<\/tr>\n
        \u00a0<\/span><\/td>\nSudden Increases in Activity Level<\/span><\/td>\nAbrupt changes in exercise intensity or duration stressing the knee joint excessively<\/span><\/td>\n<\/tr>\n
        \u00a0<\/span><\/td>\n\u00a0<\/span><\/td>\n\u00a0<\/span><\/td>\n<\/tr>\n
        \u00a0<\/b><\/td>\nFootwear<\/b><\/td>\n\u00a0<\/b><\/td>\n<\/tr>\n
        \u00a0<\/span><\/td>\nImproper Shoes<\/span><\/td>\nWearing shoes that do not provide adequate support or are unsuitable for the specific sport<\/span><\/td>\n<\/tr>\n
        \u00a0<\/span><\/td>\n\u00a0<\/span><\/td>\n\u00a0<\/span><\/td>\n<\/tr>\n
        \u00a0<\/b><\/td>\nTraining Errors<\/b><\/td>\n\u00a0<\/span><\/td>\n<\/tr>\n
        \u00a0<\/span><\/td>\nPoor Technique<\/span><\/td>\nIncorrect form or technique during physical activities increasing the risk<\/span><\/td>\n<\/tr>\n
        \u00a0<\/span><\/td>\nInadequate Warm-Up or Cool-Down<\/span><\/td>\nSkipping warm-up or cool-down exercises making muscles and joints more susceptible to injury<\/span><\/td>\n<\/tr>\n
        \u00a0<\/b><\/td>\n\u00a0<\/b><\/td>\n\u00a0<\/b><\/td>\n<\/tr>\n
        \u00a0<\/b><\/td>\nEnvironmental Factors<\/b><\/td>\n\u00a0<\/b><\/td>\n<\/tr>\n
        \u00a0<\/b><\/td>\nSurface Type<\/b><\/td>\nRunning or exercising on hard or uneven surfaces increasing the impact on the knees and contributing to cartilage wear<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

         <\/p>\n

        What causes Chondromalacia Patella?<\/span><\/h3>\n
          \n
        • Overuse: Repeated stress on the knee joint, often due to high-impact sports or activities that involve frequent knee bending, such as running, jumping, or cycling.<\/span><\/li>\n
        • Injury: Direct trauma to the knee, such as a blow or fall, can damage the patellar cartilage.<\/span><\/li>\n
        • Malalignment: Anatomical abnormalities like patellar maltracking, where the patella does not move smoothly within the trochlear groove, can cause uneven pressure and wear on the cartilage.<\/span><\/li>\n
        • Muscle Imbalance: Weakness or imbalance in the muscles around the knee, particularly the quadriceps, can alter patella’s tracking and increase stress on specific areas of cartilage.<\/span><\/li>\n
        • Degeneration: Age-related wear and tissue senescence can lead to breakdown of cartilage.<\/span><\/li>\n<\/ul>\n

          Figure 4: Theories on the development of chondromalacia patella<\/b><\/p>\n

          \"\"

          <\/p>\n

          Theories on Development and Who Is Affected<\/span><\/h3>\n
            \n
          • Mechanical Theory: Suggests that abnormal patellar tracking or alignment issues lead to increased stress on specific areas of the cartilage, causing degeneration.<\/span><\/li>\n
          • Biochemical Theory: Proposes that changes in the biochemical environment of the knee joint, such as inflammation or enzyme activity, contribute to cartilage breakdown.<\/span><\/li>\n
          • Overload Theory: Emphasises repetitive overloading of the patellofemoral joint, often seen in athletes or individuals with high physical activity levels.<\/span><\/li>\n
          • Tissue senescence: over time cartilage tissue loses its ability to regenerate\/ generate healthy tissue and recover to injury<\/span><\/li>\n<\/ul>\n

            Chondromalacia patella is common among young athletes, particularly runners, cyclists, and those involved in sports requiring repetitive knee movements. However, it can also affect older adults due to degenerative changes in the cartilage.<\/span><\/p>\n

            Figure 5: Overview of forces through the patellofemoral joint<\/b><\/p>\n

            \"\"

            <\/p>\n

            Forces in the Patellofemoral Joint<\/span><\/h3>\n

            To treat chondromalacia patella effectively, the clinician must understand the contributing forces at play in the joint.<\/span><\/p>\n

            Figure 6: Diagrammatic representation of forces through the patellofemoral joint<\/b><\/p>\n

            \"\"
            The patella has the quadricep attachment superiorly and the patellar tendon attachment inferiorly. As the tibiofemoral (knee) joint is flexed, the pulling forces on either end of the patella increases. This in turn increases the patellofemoral joint reaction force (yellow arrow). This force increases with knee flexion angles. For example, at 90\u00b0 of knee flexion, the patellofemoral joint reaction force can be several times body weight.<\/span><\/p>\n

            In cases of chondromalacia patella, this high compressive force leads to greater friction and pressure on the damaged cartilage, accelerating cartilage wear and pain.<\/span><\/p>\n

            A systematic review by Harvi F Hart et al. (2022) showed that activities with greater knee flexion (e.g., squats, stairs) generate higher patellofemoral joint reaction forces (PFJR) than those with smaller knee flexion (e.g., walking) (9).<\/span><\/p>\n

            PFJRF in Everyday Activities<\/b>: Average peak PFJRFs in healthy individuals are:<\/span><\/p>\n