TABLE 1: MUSCLE LAYERS OF THE LATERAL HIP Layer
Muscles 1. Deep Gluteus minimus
Function
n Primary stabiliser functioning to control femoral head within acetabulum
n Proprioceptive role 2. Intermediate
Gluteus medius, piriformis
3. Superficial n Significant torque producers
n Secondary stabiliser n Low load control of pelvis on femur
Tenor fascia lata (TFL), n Primary torque producers gluteus maximus, vastus lateralis
n High load control of pelvis on femur
The gluteus medius has three distinct layers (7) each with a separate nerve supply. Although the gluteus medius is often considered the primary hip stabiliser and targeted by clam shell type actions, physiologically it is unable to stabilise the pelvis on the femur in single-leg standing by itself. It has been calculated (8) that the abduction forces responsible for this are divided between the gluteus medius (70%) and the muscles attaching to the ITB (30%). The upper portion of gluteus maximus and the tensor fascia lata (TFL) both attach into the ITB and the vastus lateralis may also be considered through its fascial attachment (9).
Of the hip lateral rotator group it is actually the quadratus femoris (QF) which is of significant interest in terms of joint stability. It shows a greater reduction in muscle volume, wasting by 18% after 6 weeks bed-rest, compared to only 4% for the gluteus medius (10).
The lateral muscles are separated from each other and underlying structures by four main bursae (Table 2) each with deep, superficial and/or secondary portions.
Iliotibial band The deep fascia of the lower limb is collectively called the fascia lata. It attaches to the outer lip of the iliac crest along its full length, and throws branches to the sacrotuberous ligament, the ischial tuberosity and the pubis, effectively surrounding the upper thigh. On the lateral aspect of the thigh, this fascia is thickened to form the iliotibial band (ITB). The gluteus maximus and gluteus medius muscles insert into the ITB posteriorly and the TFL muscle inserts anteriorly. As the ITB travels down the lateral side of the thigh its deep fibres attach to the linea aspera of the femur, forming the medial and lateral intermuscular septa. The superficial
TABLE 2: BURSAE AROUND THE GREATER TROCHANTER (GT)* Name of bursa
n Gluteus maximus n Lateral n Gluteofemoral n Gluteus medius
n Caudal n Anterior to apex n Gluteus minimus n Anterolateral
Position relative to GT Approximate size (cm2 n 10–15 n 10–15 n 1.0–1.7
n 2.7–4.4 *Data modified from Woodley et al., 2008 (26) and Williams and Cohen, 2009 (2) 16 )
fibres of the ITB continue downwards to attach to the lateral femoral condyle, lateral patellar retinaculum and anterolateral aspect of the tibial condyle (Gerdy’s tubercle). A large amount of the lateral retinaculum of the patella actually arises from the ITB to form the iliopatellar band (11) having a direct effect on patellar tracking.
Contraction of the gluteus medius and TFL is transmitted
by the ITB to control and decelerate adduction of the thigh (12). Where the gluteus medius shows poor endurance and control, gait alteration may occur leading to lateral pain. In a study of distance runners (14 male, 10 female) with ITBS, significant weakness of the gluteus medius was found on the symptomatic side. Strengthening the muscle over a 6-week period resulted in 92% of the runners being pain free (13). Muscle balance tests for the lower limb (4,14) often show a reduction in abduction endurance by the gluteus medius compensation by over activity of the tightening of the TFL- ITB. Although both the gluteus medius and the TFL are able to abduct the femur, the TFL will also medially rotate the hip while the postural posterior portion of the gluteus medius is a lateral rotator (15S). As a consequence, dependence on the TFL alone for abduction power during gait causes excessive medial rotation and adduction of the hip increasing the valgus stress on the limb and therefore increasing passive tension in the ITB.
REHABILITATION Assessing lumbo-pelvic alignment The Trendelenburg test is often used in the clinic to assess control of the pelvis on the femur in single-leg standing, so is perhaps the test most relevant to lateral hip pain. With a positive test, as body weight is taken through one leg, the pelvis dips downwards away from the weight-bearing leg (Figure 2). This is known clinically as an uncompensated positive result. A compensated positive result occurs if the body is tilted (side flexed) towards the weight-bearing leg (Figure 3). A further modification of the test is to ask the client to elevate the non-weight-bearing side of the pelvis (Figure 4) and to hold this position for 30 seconds. This modification assesses the postural endurance of the lateral hip muscles. The test is positive if the client is unable to maximally elevate the pelvis or maintain the elevation for the 30 seconds (16). The Trendelenburg test is not muscle-specific but it does
give information about the client’s self-selected movement pattern that will be influenced by factors such as pain, habit and energy expenditure as well as muscle performance. Where subjects habitually hang on the hip (single-leg dominant swayback posture) the hip abductors muscles will lengthen, meaning that the Trendelenburg test cannot be held in optimal alignment. Clinically, then, it is useful to check that your client can firstly perform the test, but secondly hold the test position.
Exercise therapy
Rehabilitation (described in 3 phases) aims to correct the movement dysfunction that may be considered as a major factor in the development of lateral hip pain. Initially, our treatment aim is to lengthen the tight lateral structures and
sportEX dynamics 2012;34(October):15-23
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