We hear a lot of talk about how important the rotator cuff of the shoulder is, but we don’t often hear about the deep rotators of the hip. Similar to the shoulder joint, the hip is also a ball and socket joint. This type of joint is great in that it allows for a large degree of multidirectional range of motion. However, because of this the inherent nature of the joint is less stable than say a hinge joint like the knee. To increase stability the hip joint relies on the labrum (a fibrous ring that increases the depth of the socket) and the tiny, deep muscles that surround the joint – the rotators. Similar to the shoulder, the hip is really only attached to the body via soft tissue. Because of this reason, maintenance of a healthy balance between strength, structural stability, and flexibility is important to the overall health of the joint and surrounding structures.
For today, I will focus on the hip external rotators and the internal rotators. There are 6 external rotators of the hip – piriformis, gemellus superior, obturator internus, gemellus, inferior, obturator externus, and quadrates femoris. My guess is that most of you reading this have not heard of most of these. Okay, maybe you have heard mention of the piriformis muscle from friends or loved ones with sciatica (a whole separate topic for another day!). This small group of 6 muscles is responsible for laterally rotating the hip/leg and keeping the hip in the socket. On the opposite side of the joint lie the internal rotators – gluteus minimus, gluteus medius, and tensor fascia lata. You guessed it, these oppose the external rotators and help with activities requiring internal rotation. Individually, these muscles (both internal and external rotators) also assist with other motions in the hip, but let’s just talk about the contribution to rotation, stabilization, and possible links to low back and sacroiliac dysfunction for today.
In addition to their contribution to the rotation of the hip, these muscle groups when contracted TOGETHER provide tremendous joint stabilization. When the larger, “bulkier” muscles are doing the heavy/big work as with running, climbing, skating, kicking a ball, etc, the rotators are concurrently at work on the smaller joint motions required to allow the body to perform these activities. Since most people would probably agree that these rotators are often overlooked, I think it’s safe to assume that most of you have not focused on maintaining a balance of strength and flexibility of these muscles. Research has linked hip strength and rotation deficits with signs and symptoms suggestive of low back pain and sacroiliac joint dysfunction. In many cases, these patients present with one-sided low back and/or buttock pain and asymmetrical external and internal rotation. Long term dysfunction of these rotators can also increase compressive forces within the hip joint, leading to development or worsening of arthritic changes in the hip. If you have had persistent low back, buttock, or hip pain it might be worth a physical therapy consultation. There are many exercises, stretches and manual techniques to address these concerns and prevent further deterioration.