Prevention Better Than Cure?
WE DO BOTH!
18 Stepney Rd,
Scarborough,
YO12 5BN
01723 363332
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Prevention Better Than Cure? WE DO BOTH!
18 Stepney Rd, Scarborough, YO12 5BN 01723 363332 |
Anterior Knee Pain - Runners Knee
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Anterior knee pain is a common injury seen in the clinical setting. The condition can be related to inflammation, muscle imbalance and or instability. It can affect 60% of the athletic population. Once present it can soon turn into a chronic problem forcing the athlete to stop sport and other activities. Classification can be difficult and confusing as anterior knee pain can be present in many clinical conditions. There can also be a number of contributing causes, the longer the injury is present the harder it may be to find the cause/s. The most common conditions seen in the clinical setting which have symptoms of anterior knee pain include;
This article will specifically look at PFPS which is associated with abnormal loading of the patellofemoral joint. The patellofemoral (PF) joint consists of the femur (thigh) bone and the patella (knee cap). The patella can move in many directions controlled by several forces which provide stability and smooth tracking.
Because bending the knee increases the pressure between the patella and its various points of contact with the femur, patellofemoral pain syndrome is often classified as an overuse injury. However, a more appropriate term may be "overload," because the syndrome can also affect inactive patients. Repeated weight-bearing impact may be a contributing factor, particularly in runners. Once the syndrome has developed, even prolonged sitting can be painful ("movie-goer's sign") because of the extra pressure between the patella and the femur during knee flexion. Patellofemoral syndrome is a name used to describe Pain in and around the patella. The issue of cause and which structures are involved in PFPS is largely still unanswered. Movement At full extension the patella sits lateral to the trochlea. During flexion the patella moves medially to lie within the intercondylar notch until 130 degrees when its starts to move laterally again. The position of the patella is controlled by the quadriceps particularly the inner and outer segements. With increasing flexion a greater area of the patella aricular surface comes into comtact with the femur. loaded flexion activities subject the patellofemoral joint to loads many times the body weight. Anatomically the lateral structure are much stronger than the medial structures, so any imbalance in forces will cause the patella to drift laterally. Causes A number of factors predispose to patellofemoral syndrome and their role must be assessed as some can be corrected. Simple Causes include mal-tracking of the patella which stress the joint. It is often due to abnormalities in lower limb alignment (Q angle). Abnormal loading can develop from intrinsic or extrinsic factors. Intrinsic factors predisposing to PFPS include patella alta or baja (a patella which is positioned unusually high of low respective to the surrounding structures), deficiency of the lateral femoral condyle and quadriceps muscle atrophy. Extrinsic factors incorporate muscle imbalances and prolonged or inappropriate training leading to micro-trauma. Detailed Many individuals with PFPS will have internally rotated femurs showing either a squinting patella or secondary compensation from other areas. This can also be present with tibial rotation which is secondary to subtalar pronation of the feet. The hip structures (anterior capsule, short adductors, tensor fascia latae, iliopsoas and rectus femoris) can be stiff, restricting movement at the knee. Tightness in the iliotibial band (ITB) results in over activity of the tensor fascia lata and diminished activity in the posterior fibres of the gluteus medius. The muscle imbalance persists because shortened muscles are readily recruited and are strong whereas elongated muscles are difficult to recruit and are weak. A subject with a short ITB demonstrates excessive medial rotation of the hip during the stance phase of the walking gait which means the pelvis drops on the opposite side. Soft tissue tightness is most prevalent in growth spurts. Lateral structures are frequently tight restricting the medial glide of the patella. If the hamstring and gastrocnemius are tight it increases lateral tracking of the patella. This is because both muscles restrict how straight the leg can go and how much the ankle can bend. Restriction here will cause the foot to pronate as movement must come form somewhere to allow the body to pass over the planted foot. This in turn causes tibial rotation and knee pain. Pain is hard to localise but is usually felt behind the whole knee cap. It can vary from an ache to sharp pain depending on the activity. Going down stairs can be very painful and squatting when eccentric knee extensor activity is required. Decelerating activities being more painful than acceleration which requires concentric activity. It can sometimes feel like the knee is going to give way or lock. Assessment will show poorly controlled lower limb rotation during a variety of functional activities (step ups/downs; walking; running). For example performing a simple one leg squat may show that the knee can not stay central but falls inwards (excessive hip internal rotation), the hip may drop downwards (lateral pelvis displacement) excessive pronation of the foot may also be present (flat arches), when running its important for pronation to take place but the timing is important. The quadriceps muscles are always affected and are vitally important to retrain. The quadriceps help to control the position of the patella. It is usually found that the medial (inner) Quad be inhibited and weak. Short tight lateral (outside) structures can pull the patella out of smooth tracking as the inner quad has lost its function to pull it back to the middle. Other muscle which can contribute are hamstrings, rectus femoris (hip flexors), iliotibial band, gastrocnemius/soleus. Patella mobility can become restricted medially and caudally (towards the feet) this can lead to stiffness due to reduced range on motion. (If its not used it will lose its function). The mobility of the patella is best tested in 20-30 degrees of knee flexion as it enters the groove. A full postural and gait analyses is needed to help identify the contributing factors. If there is a muscle imbalance it means the body will compensate by altering posture. This in turn can lead to a fixed state of pain. Footwear is also vital in treatment, sometimes it may only take a change in trainers to ease the problem. It is advised to seek advice first before any changes are made. Treatment Correcting the alignment problems is of primary importance. Strengthening of the muscles showing weakness, stretching and massage for those that are shortened. One important question the therapist should be able to answer after the evaluation is whether the malalignment of the PF joint (if present) is caused by muscular structures or by static structures (retinaculum, bony confirmations, ligaments). Examining the PF joint with and without the quadriceps contracting is a good way to determine this. About 50% of PFPS patient sonly show abnormal tracking when contracting the quads. Patella taping can bring about significant reduction in pain and allow much greater function and higher levels of muscle re-training. For PF joint malalignment that is present when the quads are relaxed it is evident the problem is caused by non-muscular structures. If a bony abnormality is thought to be causing the problem then a radiograph is needed to confirm as conservative treatment is not likely to work. If any of the non-muscular soft structures are thought to be causing pain then careful palpation is needed looking for any signs of apprehension. In case of hypersensitivity ice, and gentle frictions can be applied. A tight retinaculum will need stretching manually done by the therapist. A brace may also help a tight retinaculum or a hyper mobile patella. References http://www.aafp.org/afp/991101ap/2012.html http://www.physioroom.com/injuries/knee/patellofemoral_maltracking_full.php http://emedicine.medscape.com/article/308471-overview Soft tissue differential diagnosis, diagnosis and management of anterior knee pain. Lee Herrington MCSP; SportEx Rehabilitation focus; patellofemoral joint pain; Lee Herrington MCSP; SportEx Diagnosis; evaluation and classification of patellofemoral pain syndrome; Erik Witvrouw PT, PhD; SportEx P,Brukner; K, Khan; Clinical sports medicine; (rev 2nd ED); pages 464-491; McGraw Hill.
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Clinical assessments Muscle strength Quadriceps Many PFPS sufferers will have atrophy of the quadriceps resulting in loss of strength and pain during eccentric quadriceps contractions (descending stairs). This can be measured by using a one leg squat and/or hop, looking at stability and alignment. If weakness is present than strengthening is required but which kind? Research suggests that closed kinetic chain (CKC) exercises are safer and place minimal stress on the patellofemoral joint in the functional range of motion. But most activities require open kinetic chain (OKC) strength and function. Combing the two with attention to the range of motion seems to be the best approach. For example squatting (CKC) from straight leg to 50 degrees and leg extension exercises (OKC) from 90-50 degrees to straight leg. As pain decreases the squat can be lowered but the knee extensions stay the same and should never change. As it is the eccentric contraction that causes pain it only seems functional to train the muscles in this way when pain permits. Vastus Medialis (VM) The inner quad is most frequently seen with PFPS. Its function is medial pull of the patella. This movement is crucial for proper alignment of the knee cap with respect to the femur. If weakness of this muscle is substantial it can easily be observed (patella is pulled outward and muscle bulk). It may require contraction of the inner quad to see function. With this you can see the balance or imbalance between the inner and outer quads. VM Strengthening is difficult as research shows there is no one exercise that isolates the inner and outer quad. Electrical stimulation has shown great results but isn't available to everyone. I get the patient to perform shallow squats and straight leg seated knee push downs with a towel under the knee. During these I get the patient to feel both the outside and inside quad and concentrate on the contraction of the inner quad. Also taping can help as sensory feedback. This also helps with the timing of the contraction. Neuromuscular coordination In addition to strength problems the timing of the quadriceps activation is important. The VM muscle should activate first when performing a squat I.E. descending stairs, followed by the outer quad. Sometimes this is lost but it can be hard to clinically assess. The previous paragraph explains the best approach. Gluteus medius strength The gluteus medius is mainly a hip abductor (takes the leg outwards). It also helps stabilise the pelvis, when weakness is present it can cause the pelvis to drop on the opposite side automatically causing alignment problems. Strengthening includes hip hiking lying and progress to standing. Muscle flexibility Loss of flexibility in any of the muscles surrounding the knee/hip/ankle can cause create abnormal patellofemoral stresses. Muscles mainly affected include hip flexors, piriformis, iliotibial band, hamstrings, calves. Stretching is needed to combat this. It may be a lack of stretching that has caused the knee pain to start. Stretching allows the muscles to recover and return to a normal state. Not stretching can lead to increased tone in the muscles and consequently injury. Lower limb alignment Static and dynamic evaluation of the limb is essential. Observation should be done with the patient barefoot. The lower limb is watched for causes of any compensatory mechanisms e.g. muscle weakness, muscle tightness, patellar hyper mobility. Attention should be placed on any leg length discrepancies, increased femoral and tibial rotation and intrinsic imbalances of the foot. Patellofemoral joint alignment This looks at the patella and evaluates its glide; medio-lateral tilt; antero-posterior tilt and rotation. This looks at non muscular soft structures of which can be tight or hyper mobile. |
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