Ligaments

Ligaments transmit tensile forces across the joint, define the motion limits of the bones with respect to each other and guide the relative movements of bones within the motion limits. Their ultra structure is similar to that of tendons, the principal difference being that they have a higher elastin content which ensures that joint stability is not entirely rigid. The principles of examination of an injured ligament can be applied to any joint that is readily palpable by direct com­parison with the uninjured limb:

grade 0          — normal ligament, normal joint stability;
grade 1          — tenderness at the site of ligament injury, no
                          detectable increase in joint laxity whilst            `                         loading the ligament;
grade 2          — increase in joint laxity but with a solid end point;
grade 3          — significant increase in joint laxity with no end point.

   Arthometers have been developed to quantify the amount of joint laxity and are most commonly used after cruciate ligament injury in the knee. However, as they only measure the static stability and do not take into account the dynamic stabilisers of a joint, the correlation between arthrometric estimation of joint stability and the functional instability remains poor.

    The stability of joints varies enormously from one individual to the next. Women’s joints tend to be more lax than men’s and all joints become stiffer as we grow older. Connective tissue disorders such as Ehlers—Danlos syndrome or Marfan’s syndrome should be excluded in patients with hyperlaxity. A patient should be assessed for generalised ligamentous laxity using the criteria of Wynne-Davies:

elbow hyperextension;

knee hyperextension;

foot dorsiflexion of more than 45degree

thumb can be bent back to touch volar forearm surface;

fingers can be hyperextended to parallel forearm.

    The principles of treatment for ligament injuries are as for tendon injuries. However, ligament injuries are quite commonly multiple, and because of their close proximity to joints the effect on joint motion is more pronounced.