CHAPTER 8 The hip and thigh
The hip joint
The femoral neck makes an angle (the angle of inclination) with the shaft of 120–130° in the adult, representing the adaptation of the femur to the parallel position of the legs in gait (Fig. 8.1A). This changes from 150° in the newborn to 142° by age 5, 133° by age 15, and 125° in the adult (Reid, 1992; Palastanga, Field and Soames, 1994). Greater angles than these are termed coxa valga, lesser angles as coxa vara.
Craig’s test may be used to assess the angle of anteversion; it compares the angle of the femoral neck to that of the femoral condyles at the knee. The patient lies prone on a couch with the knee flexed to 90°. The therapist palpates the greater trochanter (posterior aspect), and the femur is medially and laterally rotated until the trochanter is parallel with the horizontal plane. The angle of anteversion is estimated from the angle of the lower leg to the vertical, and angles greater than 15° are considered abnormal (Sahrmann, 2002). Interestingly, this test has been found to be more reliable than radiological assessment (Ruwe et al., 1992).
Weight bearing
In standing, each hip takes roughly 0.3 times bodyweight, increased to 2.4 times body weight when standing on one leg. Weight-bearing forces of up to 4.5 times bodyweight may be taken on the hip in running (Magee, 2002). In order to take weight most effectively, bony trabeculae line up in the direction of imposed stress. Two major systems exist within the femur (Fig. 8.2). The medial trabecular system travels from the medial cortex of the upper femoral shaft to the superior aspect of the head. This system takes vertically aligned forces created by weight bearing, and is aligned with the superior aspect of the acetabulum, the main weight-bearing region. The lateral trabecular system begins from the lateral cortex of the upper femoral shaft, crosses the medial system, and terminates in the cortical bone on the inferior aspect of the head. The lateral system is aligned to take oblique forces created by contraction of the hip abductors during gait.

Figure 8.2 Bony trabeculae of the upper femur.
After Norkin, C.C. and Levangie, P.K. (1992) Joint Structure and Function, 2nd edn. FA Davis, Philadelphia. With permission of the publisher FA Davis.
Hip ligaments
The hip joint is strengthened by three capsular ligaments: the iliofemoral ligament and the pubofemoral ligament are on the anterior aspect of the joint, while the ischiofemoral ligament is on the posterior aspect (Fig. 8.3). As the hip is flexed, all three ligaments relax. However, in extension all three ligaments are tight, with the inferior band of the iliofemoral ligament being placed under greatest tension as it runs almost vertically. It is this ligamentous band which limits posterior tilt of the pelvis (Palastanga, Field and Soames, 1994).

Figure 8.3 Capsular ligaments of the hip joint.
After Palastanga, Field and Soames (1994), with permission.
Screening examination
Muscle imbalance around the hip
The concept of muscle imbalance was covered in Chapter 5. In the hip region, the Thomas test and the Ober manoeuvre are used to assess for muscle tightness of the hip flexors (rectus femoris and iliopsoas) and hip abductors (tensor fascia lata and iliotibial band – TFL/ITB). Inner range holding ability of the gluteus medius is assessed with side-lying hip abduction and of the gluteus maximus with the prone-lying hip extension movement described below. Segmental control tests include standing hip flexion, standing hip abduction and the hip hinge (Table 8.1). All tests are described in Chapter 5.
Table 8.1 Muscle imbalance around the hip
Muscle injuries
Quadriceps
In cases of MOT, calcification is slow, with fibroblasts beginning to differentiate into osteoblasts about 1 week after injury. Radiographic evidence of bone formation is usually visible after 3 weeks (Fig. 8.4). By 6–7 weeks after injury, the calcified mass generally stops growing. Total reabsorption may occur with minor lesions, but more major conditions may continue to show remnants of the mass. The mass rarely interferes with muscle contraction, so excision is not normally required (Estwanik and McAlister, 1990).
Rectus femoris
Stretching must involve both knee flexion and hip extension and can be carried out in a side-lying position by the athlete, or by the therapist. When performing a rectus femoris stretch in standing (Fig. 8.5B), the abdominal muscles must be tightened to stabilize the pelvis before the hip stretch is applied. Failure to do so will increase the apparent range of motion by anterior tilt of the pelvis with stress thrown on the lumbar spine. Lunging actions are also useful, for both general flexibility and eccentric control (Fig. 8.5C).
The hamstrings
Biomechanics and hamstring injury
The ratio of the strength of the hamstrings to that of the quadriceps muscles (HQ ratio) is important. Normally, the quadriceps is the stronger of the two muscle groups (Table 8.2), as demonstrated by its greater volume. However, any disturbance to this natural balance may leave the weaker muscle group open to injury. The optimum value of the HQ ratio varies from 50% to 80% (Kannus, 1989), with average values in the region of 60%. After knee injury, quadriceps wasting may result in the two muscle groups producing the same power, giving an HQ ratio of 100% (Burnie and Brodie, 1986a).
Table 8.2 Percentage of strength relative to quadriceps at 100%
Hamstrings | 50–60% |
Adductors | 90% |
Abductors | 60% |
Hip flexors | 55% |
From Reid (1992).
Strength measures comparing quadriceps to hamstrings are traditionally carried out with an isometric dynamometer. However, the disadvantages of joint specificity and lack of movement make isokinetic testing more desirable. During isokinetic testing the speed of movement should match the speed of the sport as closely as possible. The speed must be quoted, as the absolute value of the HQ ratio increases as velocity of movement increases (Burnie and Brodie, 1986b). Slow speeds (45°/s) have been shown to give ratios of 60% and high speeds (300°/s) ratios of 80% (Sutton, 1984). Isokinetic testing in the standard sitting position does not allow hip motion, and movement of the limb does not occur in a closed kinetic chain, so testing is not ideal.
Aetiology of hamstring injury
A systematic review of the causation of hamstring injuries in sport (Foreman et al., 2006) was not able to reveal a single factor to be consistently associated with hamstring injury due to the wide variety of research methodologies used in studies. However six common themes were identified (Table 8.3).
Table 8.3 Factors associated with hamstring injury causation
Factor | Implication |
---|---|
Muscle strength & imbalance | Reduced hamstring strength may not be able to counteract quadriceps force during knee extension in swing phase |
Muscle control | Poor neuromuscular control may affect interaction of thigh muscles |
Flexibility | Reflects on ability of muscle to absorb shock |
Previous injury | Rehabilitation may have been inadequate or risk factors still present |
Anthropometry | Age, race, number of type II fibres and anterior pelvic tilt all implicated |
Muscle fatigue | Injuries more common while athletes fatigued, running gait change suggested |
From Foreman et al. (2006).
Exercise therapy following hamstring injury
Strength
Eccentric training
Eccentric training of the hamstrings is an important component of rehabilitation. At the end of the swing phase of gait, the hamstrings decelerate the limb by eccentric action, and so preparing the athlete for this action is essential. Eccentric training has been shown to favourably affect the length−tension curve of the hamstrings measured on an isokinetic dynamometer (Clark et al., 2005). Subjects showed a 19.4% change in the position of peak force creation towards the extended knee which may protect against eccentric overload at the end of the swing phase. Eccentric hamstring training of this type has been shown to reduce the incidence of injury in elite soccer (Arnason et al., 2008), and to successfully rehabilitate Australian rules football players (Brughelli, Nosaka and Cronin, 2009). Eccentric exercises include box drops, negative lunges and eccentric leg extension from high kneeling (Nordic hamstring exercise) (Fig. 8.8).
Closed chain actions
Closed chain exercises may be performed by modifying many common exercises. Leg rowing (Fig. 8.9A) is a useful exercise. The athlete sits on a towel (on a wooden floor) or plastic tray (on a carpeted floor) with the feet fixed. The action is to pull the body forwards by hamstring action, mimicking a rowing position. Sitting astride a gym bench or ‘form’ (Fig. 8.9B), the athlete digs the heels into the ground and again pulls the body forwards using leg strength alone. Both of these actions may be performed unilaterally or bilaterally. The slide trainer may also be used for sagittal leg pumping actions with the knees straight or bent (Fig. 8.9C). The sitting leg press weight training apparatus may be used for the sprint kick exercise (Fig. 8.9D). Instead of sitting on the bench, the athlete turns around and places the shoulder against the chair back, and the ball of the foot on the machine pedal. The action is to press the machine pedal with a combined hip and knee extension action.