The hip joint is a ball and socket joint which offers a large amount of surface area and so has a lot of inherent stability. Other factors contributing to hip stability include the “Labrum” which is a lip around the edge of the socket (acetabulum) which not only extends the concavity of the socket but also acts as a seal with the ball of the hip joint. The capsule, ligaments and muscles surrounding the hip joint are also responsible for giving added stability. Damage or malformation of any of these structures can lead to Hip Instability.
Probably the most important contributing factor is alteration or malformation of the articular surfaces. Traumatic injury causing fractures to the ball and acetabulum (the cup ) of the hip will alter the mechanics of the joint giving a sensation of the hip “giving way”.
Conditions causing malformation of the joint which may predispose to instability include Congenital Dislocation of the Hip (Hip Dysplasia), Femoroacetabular Impingment, Avascular Necrosis and Osteoarthritis are a few examples.
Damage to the labrum is usually caused by trauma such as a dislocation of the hip. The labrum splits away from it’s attachment which reduces the concavity of the acetabulum and so weakening the stability.
Capsule and Ligaments
The capsule and ligaments are the second line of defence against hip instability and can be damaged by both traumatic and non traumatic means. Laxity in the capsule and ligaments are frequently caused by sports in which sudden changes of direction with rotational torsion such as ice hockey, gymnastics, dancing, football and tennis.
Damage to the capsule, ligaments and labrum will usually need surgery to correct the instability such as tennis player, Andy Murray underwent recently. This surgery is most often performed under arthroscopy which is the least invasive form of surgery.
Instability of the hip causes the sufferer to experience feelings of the hip giving way or a sensation of not being able to trust your weight through the leg. There is often a sharp pain felt during a particular range of movement. Jumping and running increases a feeling of insecurity and may not be possible all. Standing on one leg (on the affected side) may prove unstable.
Alteration of the bony anatomy can usually be diagnosed on X Ray however an MRI would be required to fully assess damage and laxity of the capsule, ligaments and labrum.
Physical examination will involve the hip being put through a range of movements to check for slackness and crepitus (which is a sandpaper like grinding sensation in the joint) some of these manoeuvres may cause some discomfort to the patient.
Snapping Hip Syndrome
As the name describes this problem causes a “snap” or “pop” when a length of tendon is too tight to pass smoothly over a bony prominence.
When felt on the outside of the hip it is known as External Snapping Hip and is caused by the Ilio Tibial Tract (a long length of sinew which contains the muscles of the thigh) passing over a bony protuberance called the Greater Trochanter (which gives attachment to the large muscles of the bottom … the Glutei)
Internal Snapping Hip Syndrome is when the tendon of the Iliopsoas muscle tendon gets caught on the ball of the hip joint.
Internal and External Snapping Hip Syndrome are also examples of instability of the hip. Normally these conditions can be managed conservatively with physiotherapy and anti/inflammatory medication with frequent home ice treatment.
Should this syndrome prove to be so persistent that it causes pain, inflammation and a giving way of the leg on weight bearing, then arthroscopic surgery can be performed to ease the tension of the tendon. When combined with physiotherapy treatment (which will include passive stretching, cryotherapy, deep tissue massage and possibly ultra-sound if deemed required) there is a very good success for return to all activities although a regular home stretching regime will also be necessary.
By Tracey Evans – The Physiotherapy Centre
+34 609 353 805 – firstname.lastname@example.org