Joint hypermobility is the ability of a joint to move beyond its “normal” range of motion (ROM), typically due to reduced stiffness of anatomical joint structures such as the joint capsule, tendons, and/or ligaments. Joint hypermobility is an attribute of a joint and not an individual. For example, an individual may have a hypermobile elbow but not a hypermobile knee. When people think of joint hypermobility they may think of the contortionist. Contortionists typically carry generalized joint hypermobility (GJH). GJH defines the ability of an individual to extend multiple joints. GJH is more common is women and children.
Joint hypermobility and GJH are closely related terms but will often manifest with different clinical symptoms. Joint hypermobility is established by comparing the ROM of a joint to established normative data. GJH is typically assessed using the Beighton Scale (Figure 1). The Beighton Scale is based on nine movements. A score of 5 or more in adults, and 6 or more in children indicates GJH. The Beighton Scale is a tool to establish whether an individual has GJH, it is not a scale of severity. It is important to emphasize that joint hypermobility and GJH are signs and not diagnoses. Their existence does not always imply clinical consequences.
Figure 1: The Beighton Scale
Joint hypermobility and GJH may increase the risk of sustaining certain lower limb sporting injuries. A literature review conducted in 2010 found GJH was associated with a 2.5 times greater risk of knee joint injuries in all sports, and a 4.5 times greater risk of knee joint injuries in contact sports. In a study of elite-level professional soccer players, there was a greater incidence of knee injuries in hypermobile players than non-hypermobile players. During the course of one season, 9 severe knee injuries were sustained in a group of 18 hypermobile players. In a study of young female athletes, a positive measure of knee hypermobility increased the odds of anterior cruciate ligament (ACL) injury 5-fold. For athletes that underwent ACL reconstruction, re-rupture rate in the hypermobile group was 24.4% versus 7.7% in the non-hypermobile group.
Fortunately, evidence is building to support the effectiveness of specific lower limb exercises to reduce the incidence of knee injuries. Often referred to as “prehab”, these exercises target lower limb strength, balance, proprioception and correcting movement faults. Research has shown that supervised lower limb specific exercises can reduce the risk of ACL injury and increase knee joint proprioception.
In conclusion, whilst hypermobility can often be a benign condition, it may also be a clinically relevant finding. Joint hypermobility may be a considered a contributing factor in the presence of knee injuries. Adolescents and women may be at a higher risk of sustaining a knee injury if they are also hypermobile. Hypermobility also has implications for the risk of subsequent knee injury and how injuries are managed. If you feel you may be hypermobile, are looking for ways to reduce your injury risk, or have suffered a knee injury previously contact your physiotherapist at Restore Function to find out more.
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