Hip Disorders
Matthew D. Milewski
Pablo Castañeda
• Introduction
Many different conditions can affect the hip of the growing child; some occur in childhood and some can be detected at birth with findings specific for developmental dysplasia of the hip (DDH) or congenital hip deficiencies. Examples of hip problems in older children include developmental pathology (Perthes disease), neurologic manifestations (eg, hip contractures for cerebral palsy), inflammatory (infection), and neoplastic conditions. Adolescents can present with pain and lack of hip function as a result of late sequela from DDH or Perthes. The older child and adolescent can have pain and decreased function from slipped capital femoral epiphysis (SCFE) or from trauma and overuse injuries. The physical examination of the hip is crucial for any child presenting with low back, hip, or knee pain. The major innervating nerves for the hip originate in the lumbosacral region that can make it difficult to distinguish between primary hip pain and radicular lumbar pain, especially in older children. It is also crucial to examine the hip in patients presenting with a limp, leg length discrepancy, or rotational abnormality such as in-toeing or out-toeing.
• Anatomy
The hip joint is a ball and socket synovial joint designed to allow polyaxial motion while transferring load between the upper and lower body. The acetabular rim is lined by a special fibrocartilage called the labrum that adds depth and stability to the femoral acetabular joint; when this is torn, patients can complain of pain and popping. The articular surfaces are covered by hyaline cartilage that dissipates shear and compressive forces during load-bearing and hip motion.
The hip joint’s wide range of motion is second only to that of the glenohumeral joint and is enabled by the large number of muscle groups that surround the hip. The flexor muscles include the psoas, rectus femoris, pectineus, and sartorius muscle. The gluteus maximus and hamstring muscle groups allow for hip extension. The major abductor muscles such as the gluteus medius and minimus, the piriformis obturator externus and internist and quadratus femoris muscles insert around the greater trochanter. Major muscles that adduct the hip include the gracillis, adductors longus, brevis, and magnus.
There are several important growth centers in the pelvis including the triradiate cartilage that separate the ilium, ischium, and pubis bones, and this cartilage is responsible for deepening of the socket with growth. There are multiple sites of tendon and muscle attachments that originate from (or insert on) apophyseal growth centers; these areas can be subject to chronic tension and develop symptoms of tendonitis. These sites of muscle attachments can also be subject to acute severe muscle strain, and avulsion fractures can also occur (Figures 16.1,16.2,16.3). Potential sites of apophyseal injury in the hip region include the ischium (hamstring origin), anterior superior iliac spine (sartorius origin), anterior inferior iliac spine (rectus femoris origin), iliac crest (external oblique origin), lesser trochanter (psoas tendon insertion), and greater trochanter (gluteus medius insertion). The apophysis of the superior iliac spine is the last to fuse and is susceptible to injury up to 25 years old.
 FIGURE 16.1 This soccer player has an avulsion of his ischial tuberosity as a result of powerful hamstring contraction during sprinting. |
• History
Infection, inflammatory autoimmune disorders, and benign or malignant tumors can present at any age and should be considered in the differential diagnosis for hip pain or hip dysfunction; yet age can narrow the differential diagnosis and can direct the history. Perinatal, family, and birth history are important for infants who may be at higher risk for DDH. Most children have a 1/1000 chance of developing a dislocated hip. Yet other factors can increase this incidence; a firstborn female born breech into a family with a positive family history has a 1/100 chance of hip dislocation. Interestingly, infants and toddlers
with congenital hip dislocation rarely if ever complain of hip pain. In prepubescent children, history should focus on decreases in function, pain, and presence of a limp. A comprehensive review of systems (ROS) will be important and should include a history of trauma, determining the presence of fever and other systemic symptoms. Adolescent patients with hip pain should be asked about antecedent trauma or inciting activity, factors that increase or decrease pain, mechanism of injury, and time of onset questions. Other questions should document altered functions such as the ease of getting in and out of the car, putting on shoes, running, walking, and going up and down stairs. SCFE, apophyseal avulsion fractures should be considered for those adolescents with acute onset of a painful limp. In the more skeletally mature, hip pain can be the result of residual hip deformity (from old trauma, DDH, Perthes disease, or SCFE), musculotendinous strain, ligamentous sprain, contusion, or even bursitis. Degenerative osteoarthritis can occur from residual deformity but is uncommon in the childhood and early adolescent population.
with congenital hip dislocation rarely if ever complain of hip pain. In prepubescent children, history should focus on decreases in function, pain, and presence of a limp. A comprehensive review of systems (ROS) will be important and should include a history of trauma, determining the presence of fever and other systemic symptoms. Adolescent patients with hip pain should be asked about antecedent trauma or inciting activity, factors that increase or decrease pain, mechanism of injury, and time of onset questions. Other questions should document altered functions such as the ease of getting in and out of the car, putting on shoes, running, walking, and going up and down stairs. SCFE, apophyseal avulsion fractures should be considered for those adolescents with acute onset of a painful limp. In the more skeletally mature, hip pain can be the result of residual hip deformity (from old trauma, DDH, Perthes disease, or SCFE), musculotendinous strain, ligamentous sprain, contusion, or even bursitis. Degenerative osteoarthritis can occur from residual deformity but is uncommon in the childhood and early adolescent population.
 FIGURE 16.2 This hurdler has an avulsion of the anterior inferior iliac spine (AIIS) from rectus femoris contraction noted on x-ray and confirmed with MRI. |
 FIGURE 16.3 This wrestler developed acute right iliac crest pain during a match and has an iliac apophysis fracture that is noted when the pelvis x-ray is magnified. |
Key Point
Location of the pain is important because the layperson may localize “hip pain” to basic anatomical regions that may not be a sign of true hip joint pathology. Although the anterior hip and groin pain is suggestive of hip joint pathology, other common locations of “hip pain” may not be. This includes the anterior thigh (femur pathology), the posterior aspect of the hip and buttock (referred pain from the spine or SI joint), and the lateral aspect hip (trochanteric pain or abductor muscle weakness).
• Ability to Walk and Observational Gait Analysis
In children of walking age, special attention should be paid to the ambulatory status and the quality of their gait. Pain and a limp do not necessarily always coexist; for example, children with Perthes will often limp without complaining of pain. On the other hand, a refusal to bear weight in a child who was walking previously should raise the concern for a traumatic or septic origin. It can be difficult to determine the precise location of pain, and younger children may just hold the hip in a position of comfort in flexion and external rotation (the hip joint has more room for swelling when it is flexed and externally rotated). Older patients commonly express their pain localized to one of three anatomical regions: the anterior hip and groin, the posterior hip and buttock, and the lateral hip. It should also be noted that pain along the medial aspect of the distal thigh and knee can be referred pain from hip pathology.
The examination of the hip begins as the child walks to the examination room and can be further observed in shorts in the clinic hallway. It is best to examine the child’s gait from in front and behind the patient. It can also be useful to ascertain whether they are able to jog or do light running. Having the child perform toe walking, heel walking, and repetitive single leg hopping is also useful to ascertain whether a gross functional or strength limitation is present. (Please see Chapter 4 on Observational Gait Analysis.)
Patients who have pain in one of their limbs will have decreased time in stance relative to swing phase; they try to get off of the painful limb as soon as possible and transfer weight to the nonaffected
side. This is termed an antalgic gait and can be due to pathology anywhere in the limb; yet a hip source is suspected when other alterations are noted. For instance, hip pathology should be suspected in the antalgic child (decreased stance phase) with a Trendelenburg gait. By shifting the body over the affected side (Trendelenburg gait), the child decreases the force (and pain) across the affected hip. Similarly, if an adolescent has an antalgic gait with a positive foot progression angle (because their hip is externally rotated), hip pathology such as a SCFE should be considered.
side. This is termed an antalgic gait and can be due to pathology anywhere in the limb; yet a hip source is suspected when other alterations are noted. For instance, hip pathology should be suspected in the antalgic child (decreased stance phase) with a Trendelenburg gait. By shifting the body over the affected side (Trendelenburg gait), the child decreases the force (and pain) across the affected hip. Similarly, if an adolescent has an antalgic gait with a positive foot progression angle (because their hip is externally rotated), hip pathology such as a SCFE should be considered.
Stance assessment is also useful to determine if there is a limb length discrepancy as noted with asymmetry in the height of the iliac crest, or buttocks. It should be followed by a Trendelenburg test, which is a single leg stance whereby the gluteus medius of the limb in stance is tested while the contralateral limb is taken off the ground. After examination of gait, consideration should always include cursory examination of the lumbar spine, knee, and ankle bilaterally, as pathology in these areas could impact hip function. These examinations will be covered in other chapters.
• General Physical Examination of the Hip
In this chapter, we will present a general approach for examination of the hip regardless of suspected pathology and will follow with consideration of examination specific for common pathology.
General hip examination is ideally performed in a systematic manner.
Assessment of Leg and Hip Asymmetry is crucial to measure and is done with the patient in the standing (if able) and supine position. In the supine position, limb atrophy can signal a longstanding hip problem. Palpation of the muscles can identify masses. In the standing position, pelvic height asymmetry can also be used to detect a limb length discrepancy. Yet remember that hip pathology can present as a functional limb length discrepancy even though the lengths of the femur or tibia may be equal. For instance, a patient with a severe hip flexion contracture will be functionally shorter on that side. In addition, pelvic obliquity can be a result of asymmetric hip joint contracture (see below) and can also present with a functional discrepancy in length. Pelvic obliquity in the standing position can also be a result of rigid spine conditions such as lumbosacral scoliosis.
Palpation for Tenderness and Ecchymosis can signal traumatic injuries. Avulsions fractures around the pelvis are common in adolescent athletes and manifest as bruising and or tenderness to palpation along the anterior pelvic brim (for ASIS or AIIS avulsions) (Figure 16.4A and B), posteriorly along the ischial tuberosity in the gluteal fold (for ischial/hamstring avulsions) along with less commonly about the proximal femur (for greater or lesser trochanteric avulsions) (Figure 16.4C;
Video 16.1).
Detection of Hip Joint Effusion, as opposed to other joints; a hip effusion cannot be directly palpated but can be suspected based on the presence of hip that lies in a flexed, abducted, and externally rotated position (Figure 16.5).
It is in this position that accommodates the most intra-articular volume. If the leg is held in a flexed and adducted position, the examiner should be alert to the possibility of iliopsoas irritation or infection such as with a psoas abscess.
Documentation of Hip Motion is important to refine the potential differential diagnosis for hip pathology.
FIGURE 16.4 A, An athlete who avulses his anterior superior iliac spine (ASIS) as a result of severe sartorius contracture would have pain and tenderness at the examiner’s left finger. His right finger is on the iliac crest. B, A hurdler with an avulsion of the anterior inferior iliac spine (AIIS) as a result of his extreme contraction of his rectus femoris will have pain in the anterior groin with palpation and with attempted hip flexion. C, A child with greater trochanter avulsion will have severe pain over his trochanter (examiner’s right hand) and will likely not be able to walk well.
Measuring the hip range of motion has consistently been shown to be highly reliable and can be useful in identifying pathology. Hip flexion, abduction, and adduction are usually assessed in the supine position (Figures 16.6,16.7,16.8).
Hip extension and internal and external rotation are best assessed in the prone position (Figures 16.9,16.10,16.11).
Assessing pain during range of motion can be helpful in identifying inflammatory conditions, in general a hip with pathology will have limited abduction and internal rotation. Pelvic obliquity and a functional limb length discrepancy can be noted in patients with a unilateral adduction contracture. It is further important to record the range of motion at each visit and compare it with prior past measurements; there are many conditions that manifest increasing disease severity through decreasing abduction over time. For example, a child with Perthes disease and worsening loss of motion may have progressive extrusion of the hip.
FIGURE 16.5 This boy with a left septic hip lays with his hip abducted, flexed, and externally rotated. The large collection of fluid within the hip is best accommodated in this position.
FIGURE 16.6 Hip flexion.
FIGURE 16.7 Hip abduction.
The degree of femoral anteversion can also be estimated on physical exam using the technique described by Ruwe and Deluca1 by palpating the greater trochanter in the prone position and the maximum lateral trochanteric prominence was related to the degree of internal rotation of the hip (Figure 16.12).
FIGURE 16.8 Hip adduction.
FIGURE 16.9 Hip extension.
FIGURE 16.10 Hip internal rotation is best documented in the prone (hip extended) position. Any decrease in the hip internal rotation is a sign of hip pathology.
FIGURE 16.11 Hip external rotation. In general, children will have a total of 90° of hip rotation in the prone position. If there is a 60° of internal rotation, one should expect 30° of external rotation.
FIGURE 16.12 A, The examiner is palpating the greater trochanter with his right hand while the left hand internally rotates the hip. The point at which the greater trochanter is maximal is measured from vertical, and this angle is considered an estimate of femoral anteversion.
Strength Testing is done in both the supine and the prone position. Standard 5-point manual muscle strength testing should be done for flexion, extension, adduction, abduction, and internal and external rotation. Assessment of the hip muscle strength has been shown to be reliable, but appears to be less helpful in identifying specific tendinous pathological conditions. For instance, pain is nonspecific especially when it comes from the gluteus minimus or medius. Posterior pain when performing a squat can be useful in identifying gluteus medius pathology. Special tests that should be considered in this young population include the Trendelenburg test to assess for hip abduction weakness or altered hip mechanics as a result of hip varus or trochanteric overgrowth. The child should be asked to stand on a single leg for about 30 seconds without leaning to one side. The pelvis should be observed from behind to see if it dips to the opposite side (positive test) or elevates (negative test) (Figure 16.13). Again, a positive test is indicated if the pelvis drops toward the unsupported side during a single-leg stance. In children, a useful way of doing this is by having them balance by putting their hands on the examiner’s hands and determining if there is a subtle difference in the amount of force needed to maintain balance (
Video 16.2).Related posts:
Differences Between Pediatric and Adult Musculoskeletal Systems
Common Pediatric Orthopedic Nomenclature
Diagnostically Directed Examination for Infectious, Inflammatory, and Neoplastic Conditions
Evaluation for Nonaccidental Trauma
Chest and Shoulder Deformity
Pediatric Elbow and Forearm Conditions
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