Expert therapist and author of Postural Correction Jane Johnson gives advice on how to prevent and treat knee hyperextension for hypermobile populations.
Hyperextension of the knee, or if you want the scientific name Genu Recurvatum is when your knee is pushed past its normal range of motion from a straightened position. Knee hyperextension can cause serious damage and injury to the anterior cruciate ligament (ACL) or posterior cruciate ligament (PCL) and cartilage.
Expert physiotherapist, Jane Johnson gives her insight into treating and how to avoid knee hyperextension.
The book Jane refers to in this video is Postural Correction and she has pulled the information out from page 144 from the book.
Consequences of knee hyperextension
Adults who stand in knee hyperextension may have pain in the popliteal space (Kendall et al. 1993) and patellofemoral pain. People with hypermobility have laxity in knee ligaments and stand in the genu recurvatum posture. The knee is the most painful joint in people with knee hypermobility and patellofemoral pain syndrome is a common problem (Tinkle 2008).
Additionally, the normal kinematics of the knee are affected by alteration of tibiofemoral mechanics. In normal weight bearing, the femur rolls anteriorly and glides posteriorly on the fixed tibia, but in knee hyperextension the femur tilts forward, resulting in anterior compression of the femur and tibia. In weight bearing, capsular and ligamentous structures of the posterior knee are at risk of injury and this, in turn, may lead to functional gait deficits. Patients with genu recurvatum posture walk more slowly than normal and many have higher knee extensor torque values than those with normal knee posture (Kerrigan et al. 1996).
It doesn’t stop at the knee
Other joints are also affected. There is increased hip extension and decreased ankle dorsiflexion, both of which are likely to affect gait and impair sporting performance that relies on lower-limb agility. At the hip there can be excessive anterior tilt. This posture results in gait deviation and requires greater effort to maintain forward momentum (Fish and Kosta 1998).
The quadriceps and soleus muscles are shortened and knee extensor muscles are lengthened. The imbalance between knee flexors and extensors compromises the function and stability of both the knee and hip joints. Stretching of popliteus reduces its ability to rotate the leg medially on the thigh and flex the knee and therefore affects optimal knee function. There may be proprioceptive deficit near the end of range of extension (Loudon 1998). Patients may feel the sensation of knee instability.
Female athletes and swimmers
A positive correlation between genu recurvatum and anterior cruciate ligament injury in female athletes has been found (Loudon 1998). Genu recurvatum posture may predispose female athletes to overuse injuries of the knee (Devan et al. 2004). Knee hyperextension may be prevalent in some swimmers and it has been postulated that this is the result of overstretching of the cruciate ligaments due to repetitive kicking. This posture gives a greater range of anterior-to-posterior motion at the knee, but it is not clear whether genu recurvatum is advantageous to swimmers (Bloomfield et al. 1994).
What therapists can do to treat knee hyperextension
- Instruct your client in good postural alignment, helping them to identify those times when they stand with their knees locked out in the hyperextended posture.
- Apply tape to the posterior knee. Rather than prevent hyperextension, the purpose of taping is to provide sensory feedback in order to help your client identify when he/she has a tendency to hyperextend. This may be particularly useful when treating dancers with hypermobility syndrome (Knight 2011). Ultimately, self-correction of the posture is preferable to reliance on tape, which should be used only in the short term whilst your client is learning to avoid hyperextension. Tape can be applied in a variety of ways, such as a single wide strip, two narrower strips or a cross (examples of these can be found in the book). Whichever method you choose, apply the tape to the knee in a neutral position. Rather than attempt this with your client standing, ask them to lie face down, where the knee usually rests in a neutral position.
- Passively stretch quadriceps. There are many ways to do this, such as in the prone position, which stabilises the pelvis to prevent anterior tilt and lumbar extension, which otherwise reduces the effectiveness of the stretch and can be uncomfortable.
- Apply deep tissue massage to relax and lengthen quadriceps.
- If you think it falls within your professional remit, provide exercises to strengthen knee flexors. These could include regular hamstring and calf strengthening or asking your client to perform small amounts of knee flexion against the gentle resistance of your hands placed just beneath the knee within a small range of motion. Take care of your own posture when facilitating this exercise, perhaps by asking your client to stand on a raised platform so that you do not have to stoop so much.
- Consider referral to a physiotherapist for proprioceptive training and gait training.
- Consider referral to a podiatrist who may have suggestions for treatment to limit the extent of hyperextension during daily activities. For example, using a small elevated heel creates knee flexion during walking, which slows gait but can be helpful in preventing hyperextension. Use of orthotics under the medial border of the foot can help limit subtalar pronation, a posture associated with genu recurvatum. AFOs, rigid ankle and foot boots, are sometimes prescribed to help correct genu recurvatum whilst walking; although these reduce the energy requirement of walking, they do not always reduce extensor movement at the knee (Kerrigan et al. 1996).
- Consider referral to a sport therapist for sport-specific drills. This will help your client master a flexed knee position during fast, dynamic movements.
What clients can do to treat knee hyperextension
- Become conscious of knee postures during everyday activities.
- Practice good knee alignment in static postures. For example, take particular care with standing postures by avoiding locking out the knee; avoid placing the ankles on a footstool when seated because this allows the knee to sag into extension, stretching posterior tissues.
- Practice good knee alignment during dynamic functions such as standing up from a sitting position and stair climbing.
- To improve proprioception, practice single-leg balancing with the knee in proper alignment.
- Perform exercises to improve the strength ratio between knee flexors and extensors. Whilst balance between quadriceps and hamstrings may be crucial to the prevention of knee injury, unfortunately, it is difficult to state the ideal strength ratio between these muscle groups because it depends not only on the sport but also on the angle of other joints (Alter 2004).
- Consider protecting the knees against hyperextension during sporting activities, especially those involving impact such as jumping.
- Avoid exercises and stretches that force the knee into extension. For example, take care with standing hamstring and calf stretches.
- Discuss which forms of sporting activity may be most suitable for someone with genu recurvatum posture. Prevention of knee hyperextension requires focused control of the joint and could be aggravated by sports involving fast movements. This posture may be disadvantageous to participation in field sports such as rugby, football, hockey and lacrosse (Bloomfield et al. 1994). It is likely to be disadvantageous for participation in jumping sports and sports that involve excessive loading of the lower limb. Clients with hyperextended knees would be better suited to activities such as tai chi, where movements are slow and controlled. High-impact sports involving frequent changes of direction, such as racquet sports could cause more damage. Simple balancing exercises are beneficial to these clients because they adopt the neutral knee position and attempt to maintain it.
About the author
Author Jane Johnson, MSc, is co-director of the London Massage Company, England. As a chartered physiotherapist and sports massage therapist, she has been carrying out postural assessments for over 30 years. Jane has also written four other books for Human Kinetics, take a look:
If you liked this blog check out Postural assessment of the pelvis also by Jane Johnson.
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