Just want to share my post on a recent discussion the class was having!
Genu recurvatum, Knee, Gait Cycle
Genu recurvatum appears to be more common in females than males and may exist due to postural habit, increased joint laxity, or knee injury. There can be several causes of genu recurvatum and include plantarflexion contracture, spasticity of the triceps surae, quadriceps weakness, limb-length discrepancy, and hip extensor weakness. The actual beginning of this type of deformity also may be influenced by any postural adjustment to achieve limb stability and prevent anterior knee collapse. I would also like to note that Genu Recurvatum can be congenital; this is usually due to increased intraamniotic pressure and excessive estrogens at the time of birth. Congenital genu recurvatum is an uncommon condition that can happen in three different forms: congenital hyperextension, congenital hyperextension with anterior subluxation of the tibia on the femur, and congenital hyperextension with anterior dislocation of the knee joint on the tibia. (1)(3)
Genu recurvatum of the knee is a position of the tibiofemoral joint in which the range of motion occurs beyond neutral or 0 degrees of extension (1)(2). It can be divided into constitutional physiological and acquired pathological. Constitutional genu recurvatum is generally bilateral, symmetric, < 15º. Acquired genu recurvatum usually is unilateral, > 15º. (7)
With regards to anatomy, the posterior structure of the knee is likely to be stressed in an individual who displays genu recurvatum in the knee joint complex. The stability of the posterolateral compartment of the knee is provided by both capsular and noncapsular soft tissue structures, including the arcuate complex (arcuate ligament, lateral collateral ligament, popliteus muscle/ tendon, and the lateral head of the gastrocnemius), posterior capsule, lateral meniscus, fabellofibular ligament, and biceps femoris muscle.
What I found to be informative to me was how the gait cycle can be affected by genu recurvatum. During the loading response in gait, an individual with genu recurvatum transfers body weight directly from the femur to the tibia without the usual muscle energy absorption and cushioning a flexed knee provides. This may lead to pain in the medial tibiofemoral joint and posterolateral ligamentous structures. In individuals with quadriceps weakness, compensation may occur by hyperextending the knee to provide greater knee stability. Decreased step length, stride length, velocity, and cadence are primary functional gait deviations associated with this deformity. Increased lateral trunk displacement and increased energy costs also are likely to be noted.(5)
Individuals may have a history of an injury that forced them into hyperextension, examples include landing from a jump on an extended knee, a blow to the anteromedial aspect of the proximal tibia forcing the knee into hyperextension, or a noncontact external rotation hyperextension injury. Some individual may have no history of injury but may have developed knee pain over a period of time.(6)
(1) Brownstein B, Noyes FR, Mangine RE, Kryger S: Anatomy and biomechanics. In: Mangine RE (ed), Physical Therapy of the Knee, pp 1-30. New York: Churchill Livingstone, 1988
(2) Brownstein B, Noyes FR, Mangine RE, Kryger S: Anatomy and biomechanics
(6) Gait analysis By Jacquelin Perry. http://tinyurl.com/mp5eob (Google books)
(7) Genu Recurvatum Presenting as PCL Insufficiency, The Journal of Knee Surgery Vol 17 Number 4 http://www.journalofkneesurgery.com/view.asp?rID=1956
American Journal of Sports Medicine, Knee Hyperextension Galt Abnormalities in Unstable Knees http://ajs.sagepub.com/content/24/1/35.abstract