Page 36 - ISAKOS 2019 Newsletter Volume 1
P. 36

Microinstability of the Hip: Diagnosis and Treatment
Clinical Presentation
Patients presenting with hip microinstability typically complain of vague anterior groin pain. Females are more commonly affected than males. While the patient may describe a subjective feeling of instability or giving-way, these symptoms are uncommon. Mechanical symptoms, such as catching and locking, may be present. The patient might experience pain when walking, especially when the hip is extended, which levers the femoral head anteriorly. Lateral hip pain is frequently reported and is usually attributed to an overload of the gluteal tendons trying to compensate for an unstable joint. Moreover, the hip may exhibit audible clicking and snapping caused by the psoas tendon, which is also over- activated in an attempt to stabilize the joint. This condition typically is associated with participation in sports involving forceful external rotation of the hip, such as ballet, diving, gymnastics, and cheerleading. Repetitive external rotation leads to stretching of the anterior hip capsule, especially the iliofemoral ligament, causing increased micromotion of the femoral head relative to the acetabulum. Even though microinstability is more frequently observed in association with these rotational sports, it can occur in association with any sport activity and as well as in sedentary patients. It is important to look for signs of generalized ligamentous laxity. Patients frequently present with looseness of other joints and may report previous shoulder and / or patellar dislocations; however, many patients with generalized looseness of the joints do not have hip instability and not all patients with hip instability have generalized ligamentous laxity.
Physical Examination
Physical examination begins with an evaluation of hip range of motion. It is important to compare any side-to-side differences and discomfort during movement. The anterior impingement sign (pain with flexion, adduction, and internal rotation) is usually positive, suggesting an intra-articular cause of hip pain such as a labral tear. The most frequently used instability tests are the abduction-hyperextension- external rotation test, the prone instability test, and the hyperextension-external rotation test (Fig. 1). The goal of these tests is to stretch the anterior hip capsule to reproduce the pain. A recent study demonstrated that when these three tests were positive, there was a 95% chance that the patient had intraoperative signs of microinstability1. The Beighton scale is another useful test and includes dorsiflexion of the little finger beyond 90°, passive dorsiflexion of the thumb to the flexor aspect of the forearm, hyperextension of the elbows beyond 10°, knee hyperextension beyond 10°, and forward flexion of the trunk with the knees extended while the palms and hands rest flat on the floor. Assessment of soft-tissue tenderness is important to confirm possible tendinopathies associated with microinstability, such as adductor and gluteal tendinopathy.
Leandro Ejnisman, MD, PhD
University of São Paulo São Paulo, BRAZIL
Marc R. Safran, MD
Stanford University
Thomas G. Sampson, MD
Post Street Orthopaedics and Sports Medicine
San Francisco, CA, UNITED STATES
The past decade has seen a great increase in the comprehension regarding the mechanics and pathology of the non-arthritic hip. The concept of femoroacetabular impingement (FAI) changed how orthopaedic surgeons look at the hip joint. Moreover, the development of hip arthroscopy made access to the joint easier and led to an exponential increase in the number of hip arthroscopies performed worldwide. However, hip specialists soon realized that the osseous architecture was not the only factor responsible for hip pathology. The function of the acetabular labrum and the concept of the “suction seal” responsible for the negative pressure inside the joint demonstrated the need to preserve the labrum whenever possible.
Even so, some patients still present with hip pain even after correction of the osseous anatomy and repair of the labrum. New research has demonstrated the importance of the hip capsule in joint stability. These advances have led to the development of the concept of microinstability of the hip. This new entity, which may present by itself or in conjunction with FAI and / or hip dysplasia, is an evolving and exciting new field of research in hip sports medicine. The goal of this article is to describe its diagnosis and treatment.

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