CHAPTER 7

Hip and Thigh

EPIDEMIOLOGY OF HIP PAIN

HIP PAIN IN THE GENERAL POPULATION

Prevalence

•  ~3% of adult population has nonspecific hip pain

Osteoarthritis (OA)

•  Most common (MC) cause of the hip pain in the elderly

•  Symptomatic hip OA: increases with age, 2% to 10% in age >45 years (1)

•  Similar in both genders (vs symptomatic knee OA, higher in female)

HIP PAIN IN CHILDREN

•  Physis or apophysis injuries: MC cause

•  Other common causes: fracture, subluxation/dislocation, infection, and avulsions

HIP PAIN IN ATHLETES (2,3)

Prevalence

•  2.5% of all sports-related injuries and 5% to 9% of injuries in high school athletes, 0.5% to 6.2% in professional athletes

•  Higher prevalence of groin pain in some sports (eg, adult soccer players: 5%–18% and ice hockey)

      Controversial in runners (4,5)

Risk factors

•  Hip adductor muscle weakness, decreased hip range of motion (ROM), previous injuries, and muscle tightness in soccer players

•  Activities: quick cutting, accelerations, decelerations, and directional changes

•  Hip OA prevalence: higher in athletes (5.6% in athletes vs 2.8% in control subjects)

•  Risk higher in elite soccer players (up to 14%), rugby players, javelin throwers, high jumpers, track and field sports participants, National Football League players (55.6% in survey) (6)

Other common problems

•  Strain or sprain (especially adductor and gluteus), labral tear (often unclear correlation with clinical management), femoroacetabular impingement, and contusion

HIP PAIN AT WORK (1)

•  Occupational workload correlated with hip pain in men, but not in women

•  Relative risk is four to eight times higher in physically demanding job.

Higher-risk groups for hip OA

•  Male farmers and construction workers, firefighters, food-processing workers, metal workers, and forestry workers

•  Workers doing regular heavy lifting, kneeling, and crawling; limited evidence

DIFFERENTIAL DIAGNOSIS

DIFFERENTIAL DIAGNOSIS OF HIP PAIN BASED ON LOCATION (6,7)

Working definition for hip region: below iliac crest anteriorly (groin)/laterally (hip), posteriorly; thigh (below the buttock) (Flowcharts 7.1 and 7.2)

Surface anatomy (Figure 7.1)

•  Groin triangle: anterior superior iliac spine (ASIS), pubic tubercle, and midline between the ASIS and superior pole of patella

      Midline: femoral artery

•  Femoral triangle: inguinal ligament, medial border of adductor longus (not brevis), and medial border of sartorius

      Femoral vein (most medial), artery, and nerve (laterally), then iliopsoas (midline between femoral artery pulsation and ASIS)

      Underneath of iliopsoas: hip joint at the level of inguinal ligament

      Anterior recess (intracapsular) superficial to femoral neck

FLOWCHART 7.1

Differential diagnosis of musculoskeletal hip pain.

Fx, fracture; ITB, iliotibial band; MSK, musculoskeletal; OA, osteoarthritis.

FLOWCHART 7.2

Differential diagnosis of neuropathic hip pain.

MSK, musculoskeletal; N, nerve; SI, sacroiliac.

Source: Adapted from Ref. (9). Martinoli C, Miguel-Perez M, Padua L, et al. Imaging of neuropathies about the hip. Eur J Radiol. 2013;82(1):17–26.

FIGURE 7.1

Surface anatomy of the hip and groin.

Source: Adapted from Ref. (8). Falvey EC, Franklyn-Miller A, McCrory PR. The groin triangle: a patho-anatomical approach to the diagnosis of chronic groin pain in athletes. Br J Sports Med. 2009;43(3):213–220.

FIGURE 7.2

Nerve innervation in the groin area: border nerve (iliohypogastric, ilioinguinal, and genitofemoral nerves).

ASIS, anterior superior iliac spine; N, nerve.

ITB, iliotibial band; OA, osteoarthritis; TFL, tensor fascia lata.

Differential diagnosis of medial groin pain (11)

Extrinsic causes of groin pain (12)

•  Upper lumbar roots (L1–2), plexus pathologies, or superior cluneal neuropathy

•  Myofascial pain referral pattern: quadratus lumborum or paraspinal muscles

•  Vascular or ischemic pathologies: aneurysm, arterial pseudoaneurysm, or compartment syndrome

•  Intra-abdominal disorders: appendicitis, diverticulosis, or inflammatory bowel disorders

•  Genitourinary abnormalities: urinary tract infections, lymphadenitis, prostatitis, scrotal and testicular abnormalities (epididymitis), gynecological abnormalities/cysts, endometriosis, or nephrolithiasis

SNAPPING HIP (COXA SALTANS) (13)

Differential diagnosis based on the location

•  External: more common

      Friction or subluxation of the iliotibial band or gluteus maximus muscle on the greater trochanter with hip flexion

      Friction of rectus femoris on iliopsoas tendon (14)

      Pathologic (rare)

  Iliotibial band impingement on a femoral osteochondroma

  Venous hemangioma of the gluteus maximus muscle

•  Internal

      Iliopsoas tendon impingement on the iliopectineal eminence, anteroinferior iliac spine, and superior pubic ramus

  Between the two components of a bifid psoas major tendon

      Friction of the iliofemoral ligament on the femoral head

      Pathologic

  Iliopsoas tendon snapping on an anterior paralabral cyst or a protruding acetabular component of total hip arthroplasty (THA)

•  Intra-articular: loose body, labral tear or redundant synovial fold, chondromatosis, joint instability, or ruptured ligamentous teres

•  Posterior (underrecognized)

      Subluxation of the tendon of the long head of the biceps femoris muscle

      Ischiofemoral impingement with abnormalities of the quadratus femoris muscle

Prevalence: varies depending on population (up to 44% of ballet dancers), often not related to the pain

DIFFERENTIAL DIAGNOSIS OF GROIN MASS (15)

•  Hernia (direct inguinal or indirect hernia) or lymphadenopathy (Figure 7.3)

•  Iliopectineal or iliopsoas bursal effusion/ganglion cyst

In femoral triangle

•  Neuroma, aneurysm, vein (deep vein thrombosis [DVT], saphena varix), lymphadenopathy, femoral hernia, skin and subcutaneous tissues (lipoma and sebaceous cyst), psoas abscess, hematoma, or bursal effusion

      Saphena varix: reducible swelling (positional) in the groin below the inguinal ligament; differential diagnosis from femoral hernia

FIGURE 7.3

Mass in the groin region.

DIFFERENTIAL DIAGNOSIS OF HIP INSTABILITY

•  Giving way ± clicking, locking, and catching

Atraumatic instability

•  Hip pain elicited by position (hip OA)

•  Developmental hip dysplasia

•  Femoroacetabular impingement (± labral injury)

•  Down syndrome, Ehlers-Danlos syndrome, Marfan syndrome

•  Ligamentous laxity (idiopathic, congenital, acquired, iatrogenic) and generalized hypermobility of joints

Traumatic instability

•  Fracture–dislocation of the acetabulum and femoral head

•  Dislocation/subluxation of the hip (± osseous or labral injury)

•  Repetitive microtrauma

ANATOMY

BONE AND JOINT

Hip Joint

Acetabulum (adult): angled forward about 15° (anteversion) and covers two-thirds of femoral head

Labrum

•  Fibrocartilage, deepen the acetabular fossa promoting hip joint congruency, increase acetabular volume by 20%

•  Seal the articular cartilage surfaces and acetabulum

•  Essentially avascular structure; blood vessels penetrate the labrum to a depth of only 0.5 mm

•  Innervated by obturator nerve and branch to quadratus femoris (posteriorly)

Capsuloligamentous tension at the hip joint

•  Maximum articular contact of the head of the femur

      Femur in flexed, abducted, and laterally (externally) rotated position. Correction in Legg–Calvé–Perthes disease (LCPD) diagnosis used in congenital dislocation

•  Minimal intra-articular pressure with the hip in moderate flexion, slight abduction, and minimal rotation; preferred position by patient with effusion (less pain) (16)

Cartilage on femoral head consists of type II collagen and a high concentration of hydrophilic glycosaminoglycans that trap water in the substance of the cartilage and accentuate the stress-shielding properties of the joint surface

Femur

Neck of femur

•  Angled at 12° to 15° anterior to the long axis of the shaft (axial plane) (Figure 7.4)

      Increased angle (anteversion) internal rotation of femur

      Decreased angle or posterior (increased retroversion) external rotation; toe out (mild retroversion seen in slipped femoral epiphysis)

•  Femoral neck–shaft angle: (coronal plane) normal, 120° to 135°; coxa vara <120°, coxa valga >135°

•  Femoral neck is intracapsular (used as hip joint injection site) vs. greater and lesser trochanters are extracapsular

FIGURE 7.4

Alignment of the hip joint: (A) normal, (B) anteversion, (C) retroversion with position of foot (toeing).

N, nerve.

Blood supply to the femoral head and neck

•  Retinacular branches of the medial (dominant posteriorly) and lateral circumflex arteries (anterior groin) from the profunda femoris; the lateral epiphyseal vessels (main)

•  Obturator artery from ligament teres; variable in adults; 30%

Structural elements of the proximal femur

•  Trabecular pattern: facilitate load transmission through the formation of three distinct arcades arranged at 60º orientations to manage the tensile and compressive forces experienced by the femoral head and neck

      Medial trabecular system for the vertical compressive forces to the cortical bone

      Lateral system will transmit shear forces of body weight and ground-reaction force to the cortical bone

  Lateral pattern: The lateral forces will go laterally and up into the pelvis

•  The cortical structure of the femoral neck is thicker at the inferior margin as an adaptation to these loads

LIGAMENT

Anterior (Figure 7.5)

•  Iliofemoral ligament: anterior inferior iliac spine to intertrochanteric line of the femur

      Superior band: thickest and strongest; prevents hyperextension, and resists anterior translation

      Medial (vertical) and lateral; Y ligament of Bigelow

  Restrict external rotation in both flexion and extension and internal rotation in flexion

•  Pubofemoral ligament: inferiorly located; prevents excessive abduction

•  Ligament teres: conduit for the secondary blood supply from the obturator artery and for nerves to travel along the ligament

      In childhood, primary retinacular artery cannot travel through epiphysis

Posterior

•  Ischiofemoral ligament: ischium to the neck of the femur, tightened by flexion

FIGURE 7.5

Ligaments in the hip joint.

ASIS, anterior superior iliac spine.

NERVE

Cutaneous nerves (see Figure 7.2)

Femoral nerve: L2–4, posterior division, runs between iliacus and psoas muscle femoral nerve lateral to artery (vein medial to artery), but not contained in the femoral sheath, traverses midline of inguinal ligament

•  Motor branches: sartorius, pectineus, and quadriceps

•  Sensory branches: intermediate and medial femoral cutaneous nerves

Obturator nerve: L2–4, anterior division, formed within the psoas major muscle

•  Runs over the pelvic brim the obturator foramen (posterior to ramus), then between superior and inferior pubic ramus (posteior to anterior) either anterior or posterior to obturator externus/adductor brevis (entrapment site)

•  Anterior branch (more common pain generator): motor to adductor longus, brevis, and gracilis muscles and sensory fibers to the skin (distal two-thirds of the medial thigh) and fascia of the medial aspect of the mid-thigh, articular branch to the hip joint)

•  Posterior branch: pierces and innervates the obturator externus motor branch (adductor magnus) and sensory branch to knee joint (articular capsule, cruiciate ligaments, and synovial membrane)

Sciatic nerve

•  Runs between medial and lateral hamstring muscles

      Lateral to the semimembranosus under the biceps femoris tendon at the level of the ischial tuberosity: chronic tendinopathy causes sciatic nerve irritation at this level (17)

•  Tibial nerve: semimembranosus, semitendinosus, and biceps femoris long head

•  Peroneal nerve: biceps femoris short head (only muscle innervated by peroneal nerve above the fibular head)

MUSCLE (FIGURE 7.6)

BIOMECHANICS

KINEMATIC AND KINETIC (18,19)

Hip joint movement

•  Multiaxial ball-and-socket joint, mostly rotational movement, no detectable translational movement

•  Depth of acetabulum deciding absolute limit of range (in addition to other factors)

•  Retro and anteversion; angle between the posterior intercondyles (at the knee) and femoral neck (see Figure 7.4)

      Affects rotation of the femur, knee, tibia pronation or supination, location of patella on the intercondylar groove, and can cause leg-length discrepancy

•  Muscles across the joint: gluteal muscle, iliopsoas, adductor, rectus femoris, and hip external rotator muscles; stability and tightness affect movement

      Tight hip flexor with iliopsoas tightness (common in office workers, wheelchair ambulators)

      Tight rectus femoris/iliopsoas (anterior tilting of the pelvis) versus hamstring (posterior tilting); affects the spine’s sagittal alignment

      Hip retroversion or hyperpronation; external rotation of the femur; shortened hip external rotator

•  Extension reserve concept: the range of hip extension from the standing position: up to ~15°

      Pelvic retroversion (to decrease the lumbar lordosis) hip constantly extended and hamstring shortened in this position mechanical disadvantage in shortened hamstring affects the sagittal alignment of the spine

Hip joint motion in activities of daily living (ADLs) (20)

•  Tying shoe with foot on floor 124° on the same side, 110° on the opposite side in sagittal plane

•  Squatting 122°, sitting down and rising 104° in sagittal plane

FIGURE 7.6

Muscles in the hip region.

•  Ascending stairs versus descending: 67° versus 36° in sagittal plane

•  Running: ~140° of flexion/extension range, but slow-paced jogging only requires 40°

•  Jogging: propelled forward moment through hip flexion and knee extension rather than pushing off from ankle plantar flexion

Center of gravity (COG): within the pelvis, anterior to 2nd sacral vertebra, midline (medial to the hip joint)

•  Fulcrum in the hip joint; hip abductor (short lever arm) counterbalancing body weight (opposite longer lever arm of the fulcrum)

Kinetics of the hip joint (at the center of femoral head)

•  Joint reaction force (reflecting force on the joint): result of the need to balance the moment arms of the body weight and abductor tension

      Bipedal stance: support two-thirds of the body weight (upper body and trunk); each hip supports one-third of the body weight

      Unipedal stance: support five-sixths of body weight (2/3+ 6/1; one lower limb)

•  Joint reaction force on the hip with different activity

      Walking: 2.5 × body weight, jogging: 5 × body weight, some athletic activity (stumbling) >8 × body weight

      Further increase in single stance during kicking, jumping, or cutting in

•  Therapeutic implication: to decrease joint reaction force

      Lever arm from the midline (center of mass to the hip joint; fulcrum)

      Shift body weight over the affected hip or weak hip abductor

      Decrease hip joint moment: (upper body weight + one lower leg weight) × lever arm (body weight)

  Trendelenburg and use of cane (shorten the lever arm for body weight by shifting the COG laterally)

           –  Use of cane contralaterally; decreased muscle activity (EMG) of hip abductor by 40%

HIP STABILITY (21)

Stabilizers

•  Bony stabilizer: acetabulum

      170° of femoral head coverage

      Orientation: anterior tilt; anteversion ~20° more posterior coverage; allowing more flexion than extension

      Hip: most stable in full extension

•  Soft tissue stabilizer

      Labrum: extend acetabular coverage and ensure negative intra-articular pressure

      Ligaments: iliofemoral, pubofemoral, ischiofemoral, and ligamentum teres (unclear function, free nerve ending, but hypertrophy can cause instability)

      Iliopsoas and muscles around hip joint (gluteus, hip external rotator, etc); dynamic stabilizer

PHYSICAL EXAMINATION

INSPECTION

On standing: check the posture, leveled pelvis (posterior iliac crest), and exaggerated/diminished lumbar lordosis

Observation of gait: antalgic gait pattern (Trendelenburg, hip lurch, or slight hip flexion)

Pelvic tilt (lateral) and anterior (exaggerated lordosis) and posterior tilt (flat back)

Gross atrophy of quadriceps and hamstring muscles

Alignment of femur: coxa vara or valgum, ante-/retroversion (affecting direction of patellar facing)

•  Coxa vara with genu valgum and anteversion (patellar or intercondylar groove facing medially)

•  Ante-/retroversion; hip internal/external rotation on prone

      Check foot angle (tibial torsion) and forefoot deformity (metatarsus adductus) in addition to hip anteversion for toeing in

Leg-length discrepancy (22)

•  Compare the length of ASIS (or umbilicus) to medial malleolus and Galeazzi sign with hip and knee flexion; height of the patella (can be affected by pelvic rotation; check the ASIS height)

•  Causes: developmental hip dysplasia, previous fracture, dislocation, tumor, osteomyelitis, and functional discrepancies

•  Up to half inch; well tolerated by the patient (therefore, no need for lift)

PALPATION

Anterior

•  ASIS: start from lateral iliac crest and palpate the prominence anteriorly

•  Femoral artery: midline between the pubic tubercle and ASIS

•  Pubic symphysis palpation on supine (at the midline) for tenderness, gap, or overriding

Lateral

•  Greater trochanter: lateral side, bony prominence on lateral or standing, a hand breadth below the ASIS

Posterior

•  Ischial tuberosity: at the level of greater trochanter on 90° hip flexion

RANGE OF MOTION

Varies depending on the examination position, age, and gender: check for symmetricity

Flexion: tightness of hip flexor muscle/capsule; common in person sitting all day or in wheelchair

Hamstring-popliteal angle for hamstring tightness (hip 90° flexion, then extend the knee gradually)

•  Useful to follow up the progression

SPECIAL EXAMINATION

ASIS, anterior superior iliac spine; FABER, flexion, abduction, external rotation; FADIR, flexion, adduction, and internal rotation; ITB, iliotibial band; SI, signal intensity; TFL, tensor fascia lata.

DIAGNOSTIC STUDIES

FLOWCHART 7.3

Diagnostic approach and management of hip pain.

AVN, avascular necrosis; CBC, complete blood count; CRP, C-reactive protein; ESR, erythrocyte sedimentation rate; FU, follow-up; PO, per os (oral); POC, point-of-care; PT, physical therapy; US, ultrasound; W/U, work up.

PLAIN RADIOGRAPHS (28)

Indications

•  Chronic pain (>3 months): degenerative joint disease or inflammatory joint disease

•  History of trauma or any red flags

Technique (29)

•  Anteroposterior (AP): standing including pelvis (see Figure 7.7)

•  Frog lateral view (abduct the hip): proximal femur, leg length, degenerative (better for osteophyte evaluation in femoral head than AP view), or dysplastic changes or bony lesion (30)

      Cross table lateral (in trauma or acute pain, no need for hip abduction), Dunn view (to check femoral head spericity or femoral neck anteversion)

      Other fractures: pelvic trauma (inlet/outlet view), acetabular fracture (Judet view)

FIGURE 7.7

X-rays of (A) adult hip and (B) pediatric hip.

Common findings

•  Hip OA: osteophytes, joint space narrowing, sclerosis, and subchondral cyst formation

•  Hip femoroacetabular impingement; pistol grip in cam type and cross-over (crossing of anterior and posterior wall outline medially rather than superiorly/laterally) in pincer type (common in asymptomatic young populations)

•  Hip dysplasia: the center-edge angle, the femoral neck–shaft angle, and the vertical-center-anterior angle

      Limited reliability

•  Stress fracture: cortical thickening, possible lucent line in fatigue fracture, ill-defined linear sclerosis in insufficiency fracture. Plain radiograph is not sensitive

POINT-OF-CARE ULTRASONOGRAPHY (31,32,33)

Indications

•  Tendon and muscle injuries, effusion or synovitis within the hip joint or adjacent bursa

      Dynamic evaluation for snapping (especially external)

•  Interventional: guidance for intra-articular hip joint injection (anterior recess or intracapsular) or bursal injection, or ultrasound (US)-guided nerve block (lateral femoral cutaneous nerve)

Setting

•  Frequency: 12 MHz for superficial nervous structures; muscle: 8 to 12 MHz, and hip joint: 5 to 9 Hz

•  Depth: depending on the patient’s body habitus, 3 to 7 cm

Protocol

•  Modified from the American Institute of Ultrasound in Medicine (AIUM) guidelines

•  Anterior: oblique sagittal and transverse (with slight hip abduction)

      Femoral head, neck, joint, capsule, labrum (part)

  Joint effusion: distension >5 mm indicates >5 to 10 mL of fluid (2.7 mL in asymptomatic group)

  Synovitis with increased vascularity, intra-articular loose body

  Paralabral cyst

  Cortical disruption in femoral neck

      Tensor fascia lata, iliopsoas, rectus femoris (direct and reflected head), and sartorius

  Enthesopathy (calcific tendinopathy), avulsion, tear

      Bursa: iliopectineal and iliopsoas bursal effusion

      Femoral nerve, saphenous or possibly anterior femoral cutaneous nerve

      Dynamic view for snapping, anteriorly iliopsoas bursa (iliopectineal eminence)

•  Medial: hip external rotation with 45° knee flexion, sagittal oblique

  Adductor muscle (adductor longus, gracilis), pubic tubercle (osteitis pubis)/symphysis

•  Lateral hip: lateral decubitus, transverse and longitudinal

      Greater trochanter, gluteal tendon, and bursa

      Snapping iliotibial band (ITB) (thickened TFL/ITB over the greater trochanter) during flexion and extension

      Morel-Lavallée lesion (posttraumatic seroma)

•  Posterior: hip flexed (to tighten the hamstring) and extension to follow sciatic nerve

      Hamstring tendon, ischial tuberosity, and ischiogluteal bursal space

MRI/MRA (34)

Indications

•  Gold standard test for intraosseous and intra-articular (labral or ligament) abnormalities; better anatomic overview because of larger field of view than ultrasonography

      Stress/insufficiency fracture when plain imaging is negative or to evaluate tumor/infection (if + red flags)

•  More sensitive in deeper/proximal muscle pathologies (psoas and iliacus muscle) and tendon injury (hamstring and gluteal muscle) than US and may be more predictive of injury

•  Evaluation of hernia (direct, indirect, and sports hernia), stress injury of symphysis pubis (osteitis pubis)

•  Bursal effusion (iliopsoas bursa) in relation to hip joint capsule effusion

Technical considerations

•  MR arthrography for intra-articular lesion (labral tear) better than MRI

      Relatively low sensitivity and high specificity in cartilaginous pathologies (delamination tears)

•  MRI of pelvis often required (for adductor strain, osteitis pubis, sports hernia, or posterior hip rotator muscles)

TREATMENT

NONOPERATIVE MANAGEMENT

Patient education

•  Use cane on the contralateral side to decrease the workload of hip abductors (gluteal muscle) to decrease joint reaction force (35)

•  Avoid irritation of superficial nerve (eg, lateral femoral cutaneous nerve) by clothing, tight belt, and so on

•  Education of training errors or external factors

•  Weight loss as well as good rest, nutrition in the athletic population (for energy balance, nutritional balance with calcium and vitamin D supplementation)

•  Stay active

      Exercise in a pool when available if in significant pain; well tolerated

      Continue upper body exercise (eg, using upper body ergometer/bike)

•  Use a high chair (avoid deep squatting) although ROM a few times a day is strongly recommended despite pain unless there is contraindication

Physical therapy (PT) and home exercise program

•  Strengthening exercise of the gluteal and core muscles education

•  Stretching

      Hip external rotator; piriformis, obturator internus/gemelli muscles

      Adductor, flexor, hip abductor (ITB band), hamstring, and knee extensor

      Manual therapy technique can be utilized: counter strain, myofascial release, and so on

•  Joint proprioceptive exercise and balance exercise

•  Modalities: US (deep heating) or cold modalities usually provide temporary pain relief

•  One session of PT occasionally for proper assistive device use education

Orthosis

•  Bracing: articulated hip orthotic (abductor brace)

      Rarely used in general outpatient clinic except postsurgical, such as hip arthroplasty or developmental hip dysplasia (for Pavlik abduction harness)

•  Heel lift (up to 0.5-inch) or shoe lift for leg-length discrepancy; no intervention up to 0.5-inch difference; check and address pelvic malalignment (rotation)

Injection

•  Soft tissue injection (bursa, tendon and ligament, etc)

      Injectate: steroid (for bursitis), prolotherapy, and platelet-rich plasma (PRP) (chronic pain with tendon/ligament injury)

•  Joint injection

      Positive response to intra-articular injection; good indicator of the pain source from intra-articular pathologies (eg, labral injury as source of pain)

      Steroid injection: either fluoroscopy guided (obese population) or US guided (36)

      Viscosupplementation and PRP injection can be considered in patients who do not respond to steroid injection

•  Nerve block (used with US guidance and/or nerve stimulator)

      Lateral femoral cutaneous nerve for meralgia paresthetica: slightly distal to the ASIS, under/deeper to the fascia iliaca (vs femoral nerve, which is above/superficial to fascia iliaca) then over the fascia distally

      Iliopsoas and ilioinguinal nerve between internal oblique and transverse abdominis near ASIS (cephalad-medial to ASIS)

      Obturator nerve for medial thigh/groin pain; anterior division between adductor longus/brevis (or pectineus/adductor longus, a few cm distal to pubic symphysis with hip abduction position

      Medial femoral cutaneous nerve for anterior thigh pain

SURGERY

Arthroscopy (37)

Indications

•  Failed conservative treatment with persistent pain for femoroacetabular impingement, labral pathology (labral tear, capsular laxity)/snapping, other intra-articular pathologies; chondral lesion or loose bodies

Positions and approaches: supine or lateral position on a distraction table

•  Portal placement: anterolateral portal (anterior superior to greater trochanter), anterior (bisection of the vertical line from ASIS and horizontal line from greater trochanter) and posterolateral (2–3 cm posterior to greater trochanter) portals

Complications (38)

•  Heterotopic ossification (MC reported), nerve injury (pudendal and sciatic or others) by traction, portal placement, or scuffing

•  Iatrogenic chondrolabral injury, iatrogenic instability resulting in subluxation/dislocation, extravasation of fluid into the intra-abdominal cavity, femoral neck fracture, hematoma, thromboembolic disease

Total Hip Arthroplasty (THA) (39)

Indications

•  Advanced OA or failed conservative treatment for disabling pain from OA

Surgical approaches (40)

•  Direct anterior: less commonly done than other approaches, muscle sparing, earlier restoration of gait, low rate of dislocation

•  Direct lateral: adequate exposure to proximal femur and acetabulum, low dislocation rate

•  Posterior (posterolateral) approach: spare the abductor muscle, extensive exposure, posterior dislocation: more commonly done

Complications

•  Pain

      MC cause: aseptic loosing and infection

      Extrinsic factors: heterotopic ossification, stress fractures, spinal pathology, vascular lesions, referred pain from the retroperitoneum and abdomen, and soft tissue inflammation such as tendinopathies or bursitis

•  Wound infection: suspicious for infection if drainage more than 4 days (also can be fat necrosis)

      Either immediate postoperative or delayed infection

      Delayed infection: presents with pain usually, methicillin-resistant Staphylococcus aureus (MRSA) (MC cause)

  X-ray: radiolucency or new bone formation fine needle aspiration

  Urgent surgical referral (needs excision, temporary implant with local antibiotic therapy and intravenous [IV] antibiotic; then reimplant of new prosthetic)

•  Dislocation depending on the surgical approach, abductor insufficiency, and fracture

•  Heterotopic ossification

      Persistent pain, swelling, and warmth for 2 to 3 weeks

      Postoperative irradiation for prevention

•  Peripheral nerve injury

      Risk factors: revision surgery, limb lengthening, female gender, congenital hip dislocation, increased blood loss, and increased surgical time

      Good prognosis. MC persistent complaints: dysesthetic pain

•  DVT prophylaxis (up to 4 weeks) because it develops usually late in THA

      Lower-molecular-weight heparin is better than Coumadin

Perioperative rehabilitation

•  Preoperative exercise

      About 12 weeks of aerobic exercise or resistance exercise

      Supervised PT focusing on strengthening, ROM exercises, and functional training for 12 weeks

      Joint protection technique and energy conservation principle

      Psychological impairment intervention

•  Postoperative exercise

      Hip abductor strengthening, stair climbing exercise, and use of armchair (markedly reduce forces across the hip)

      Exercise after THA

  Cycling is the least stressful. Diving, golfing, and bowling are acceptable sports after THA.

  Running, waterskiing, football, baseball, and basketball are discouraged

      Crutches: reduce the lateral hip force by 30%

•  Patient education and precaution

      Dislocation

  Posterior approach: 6 weeks in uncomplicated and 12 weeks in complicated dislocation

  In high-risk patients: hip spica or hip abductor with knee ankle foot orthosis (KAFO; hip flexion stop at 80°, abduction 20°, and external rotation 10°)

      Weight bearing usually cleared by surgeon. Generally, full weight bearing in all cemented or proximally fitting uncemented THA implants, unless there is the presence of a trochanteric osteotomy, fracture, bone grafting, significant acetabular or femoral bone loss, or other unusual occurrence

      Driving after THA

  About 1 to 6 weeks after operation: left THA within 1 week of operation, and right THA 4 to 6 weeks postoperation

      Leg-length discrepancy after THA

  Functional: pelvic obliquity from muscle imbalance, abductor contracture, tight capsular structures, knee flexion contracture, or spine abnormality

  Do not correct the discrepancy for 6 months after surgery

JOINT AND BONE PATHOLOGY

OA OF HIP

Introduction

•  Epidemiology

      Prevalence: 7% to 17% (varies depending on different studies); higher with increasing age

  Radiologic findings of hip OA: up to 27% (41)

      Female > male, White and African American > Asian, unilateral (especially with history of [h/o] trauma) > bilateral (obesity) (42)

      MC cause of chronic hip pain in elderly patients

•  Risk factors

      Age (>50 years), obesity, genetics, childhood hip disorder (hip dysplasia and slipped capital femoral epiphysis), femoroacetabular impingement, labral tears, and sequel of avascular necrosis

      Sports with high loads or sudden irregular impacts; repetitive injuries are likely; soccer and track

  Running: equivocal, may be increased in the subgroup with biomechanical abnormalities (vs protective of cartilage)

History and physical examination

•  Insidious pain in the groin (buttock; underrecognized) and morning stiffness (<1 hour)

•  Decreased range ± pain, especially internal rotation

      The position of the femoral condyle being deeper in the acetabulum with internal rotation

      Capsular pattern of restricted ROM: first internal rotation loss followed by decrease in abduction and flexion

Diagnosis

•  Clinical diagnosis supplemented by imaging study

•  Differential diagnosis

      Inflammatory arthropathy

  Pain worse in the morning, prolonged stiffness, systemic involvement, enthesopathy, skin or bowel symptoms

  Elevated erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), white blood cells (WBC) in joint fluid; 2,500 to 50,000/mm³

      Femoroacetabular impingement, labral tear, or protrusio acetabuli

      Avascular necrosis (especially with risk factors)

      Septic arthritis (younger individuals, especially with risk factors, red flags)

      Synovial chondromatosis, pigmented villonodular synovitis

      H/O trauma: acetabular fracture or femur fracture (proximal femur)

      Trochanteric tendinobursitis (snapping hip syndrome, adductor strain); often concomitant

      Referred pain to hip (L2–3 radiculopathy/plexopathy, SI joint dysfunction or coccydynia)

•  Imaging studies

      X-ray (AP, frog leg lateral): joint line narrowing, osteophyte, subchondral sclerosis, and cyst

      MRI: not necessary for diagnosis, but for differential diagnosis for intra-articular and intracortical lesion if atypical presentation or red flags present

Treatment

•  Patient education (weight loss, cane use), pain medication (acetaminophen, nonsteroidal anti-inflammatory drug [NSAID] weak opioid (eg, tramadol if not responsive to NSAID or acetaminophen)

•  Physical therapy (PT) (43,44)

      Stretching of iliopsoas, rectus femoris, iliotibial band, and hamstring muscles; dynamic-balance exercise, and gluteal/quadriceps muscle strengthening

      Adaptive equipment evaluation, avoid low-seat chair, and so on

      Cane to decrease pull of hip abductor muscle (28,45)

•  Injection

      Corticosteroid: cautious about steroid-induced bone disease

      Hyaluronic acid (46) under US or fluoroscopy guidance (47)

      Consider platelet-rich plasma injection and prolotherapy if steroid and viscosupplementation fail

•  Surgical referral (48)

      Hip replacement: advanced OA after failed conservative treatment

  Resurfacing: metal on ceramic rather than metal on metal

  Minimally invasive versus conventional incision; no significant difference in outcomes

LABRAL TEAR

Introduction (49,50)

•  The most common form of intra-articular pathology, often asymptomatic, may be related to early hip OA

•  Anatomy of labrum: thin fibrocartilaginous structure; enhance the congruity and stability of the femoroacetabular joint

•  Classification

      Location: anterior (antero-superior more common) and posterior tear

      Morphological: radial flap, radial fibrillated, longitudinal peripheral, and unstable tears

•  Etiology

      Femoroacetabular impingement, hip dysplasia, trauma/dislocation, capsular laxity, and joint degeneration

      Increased incidence with developmental dysplasia of the hip and LCPD

      Trauma and overuse: repetitive cutting, jumping, and twisting during sports

  Anterior: hyperextension, pivoting injury, and external rotation: most symptomatic (golfer)

  Posterior: axial loading in a flexed position

History and physical examination

•  Often asymptomatic

•  Groin pain (deep aching) ± painful clicking, transient locking and “giving way” of the hip

      Pain with Buddha position

•  Physical examination: provocative tests; low sensitivity

      Pain with anterior impingement position (flexion, adduction, and internal rotation [FADIR]) or (flexion, abduction and external rotation [FABER] to extension, adduction, and internal rotation [IR])

      Posterior impingement (hyperextension, abduction, and external rotation)

Diagnosis

•  Clinical suspicion confirmed by imaging study or arthroscopy

•  X-ray to rule out (R/O) OA, dysplasia, and loose body

•  MRI/MR arthrogram

      Normal labrum: a triangular structure of homogeneously low signal intensity (SI) on all pulse sequences

      Typical findings: linear hyperintense T2 SI contacting the labral surface

      Associated findings

  Subchondral bone marrow edema and/or cystic changes

  Osseous fragmentation at the superior acetabulum

  Paralabral cyst: highly specific finding

•  Differential diagnosis: similar to hip OA, avascular necrosis (AVN), stress fracture, referred pain from L2 to L3 radiculopathy, intra-abdominal or gynecologic disorder, or snapping hip syndrome

Treatment

•  Nonoperative treatment: activity modification, NSAIDs/pain medication, gluteal muscle strengthening, dynamic-balance exercise, and cane or crutches

•  Injection (51) for pain relief

      Steroid: limited clinical benefit as therapeutic modality (average duration of benefit 10 days) in femoroacetabular impingement (FAI) with labral tear

      Good indicator for response to surgical procedure

•  Surgical referral for arthroscopic debridement if failed conservative management

•  Return to play: 6 weeks (golf) to 12 weeks (baseball or soccer); intervention to bony abnormalities: longer

FEMOROACETABULAR IMPINGEMENT

Introduction (52)

•  Hip joint damage because of abnormal mechanical contact of the acetabular rim and the proximal femur (head–neck junction)

      May cause labral tears, cartilage lesions, and eventually premature OA

•  Epidemiology: unknown incidence, high prevalence of asymptomatic morphologic abnormalities (15%–25%) (53)

      Cam lesion: more common in young active males and pincer lesion: more common in middle-aged active women

•  Classification based on the location of the morphologic abnormalities (see Figure 7.8)

      Cam impingement: abnormality in the anterior femoral head–neck junction

  Pistol-grip deformity: the prominence of the femoral head–neck junction can be seen as an overall decreased offset at the femoral head–neck junction

  Often associated with anterior superior labral lesion: chondrolabral junction

      Pincer impingement: retroverted acetabulum

  Associated with posterior inferior labral lesion, intrasubstance labral tear

      Mixed cam and pincer: MC

FIGURE 7.8

Femoroacetabular impingement: cam and pincer type.

•  Risk factors

      H/O slipped capital epiphysis, LCPD, osteonecrosis, and malunited femoral neck fracture (cam type)

      Supraphysiologic flexion or rotational movements, repetitions, and forceful motions

History and physical examination

•  History; similar to hip OA

      Gradual onset of mild groin pain (less commonly buttock pain) with activities involving hip flexion (crouching, sitting) and weight bearing

  Significant limping is unusual. If pain is significant, consider other etiologies

      Stiffness or start-up pain and limited ROM (eg, “difficulty with tying shoe”)

      ± Symptoms from concomitant findings (labral tear)

•  Physical examination

      C sign: patient holds the hip when asked of the location of the pain (hip pathologies, not specific)

      Limited flexion <90°, decreased passive external rotation more than internal rotation ± anterior impingement test, pain with FADIR (or internal/external rotation)

Diagnosis

•  Clinical suspicion confirmed by imaging finding

•  Differential diagnosis

      Developmental dysplasia of the hip (eg, acetabular abnormality)

      Decreased acetabular anteversion or coxa profunda (deep acetabular socket)

      Acetabular protrusion (displacement of acetabulum and femoral head medially); primary or secondary (rheumatoid arthritis [RA], metabolic disease, or postsurgical)

      Coxa vara

      AVN, stress fracture (sacral), ischiofemoral impingement, plica lesion, synovial chondromatosis, and so on

•  Imaging (54)

      X-ray: AP and modified Dunn view (hip flexed 90° and abduction 20°)

  Other lateral views: cross table lateral and false-profile view, often missing deformity

  Acetabular retroversion

           –  Center-edge angle: vertical line drawn through the center of the femoral head and a line drawn from the anterior edge of acetabulum to the center of femoral head; abnormal if >40º more coverage of the anterior rim of the acetabulum compared with the posterior rim

           –  Crossover sign; anterior rim over coverage (55)

  Flattened head–neck junction, pistol grip deformity (cam) in AP and lateral view

      MRI

  The alpha angle (aspherical shape); cam impingement ≥55° (Figure 7.8)

           –  Axial plane, between two lines from the center of the femoral head through the middle of the femoral neck and a line from the center of femoral head to where the contour of the femoral head–neck junction exceeds the radius of the femoral head

           –  False positive: abnormality of the shape of the femoral head–neck junction such as a wide femoral neck, osteophytes, or posterior displacement of the femoral head

Treatment

•  Nonoperative management: activity modification, NSAID, exercise to prevent deconditioning

      PT: increase passive range of motion (PROM) and stretching (may exacerbate symptoms), strengthening and neuromuscular training

•  Injection: diagnostic (positive response is good indicator for intra-articular hip pathology and response to surgery) and symptom relief

•  Surgery (48)

      Open and arthroscopic procedure to debride the labrum, remove some of the femur (femoral osteoplasty) and/or acetabular osteotomy

      Complications: peripheral nerve injury, trochanteric nonunion, osteonecrosis of the femoral head and femoral neck fracture

      Postop: protected weight-bearing precautions for at least 4 to 6 weeks (56)

  Return to full activity as early as 3 months. Premature return to activity: concern for femoral neck fracture

AVASCULAR NECROSIS OF HIP

Introduction (57)

•  Epidemiology: ~15,000 cases per year, male ≥ female (equal or higher depending on different studies), peak incidence between 2nd and 5th decades, and 40% to 80% bilateral

•  Etiology (58)

      Risk factors: multifactorial, genetic, variation of vascular anatomy (absence or hypoplasia of the superior capsular artery), trauma, radiation, sickle cell disease (trait, caisson disease, myeloproliferative disease, etc), steroid (high dose, >20 mg/d, >2 g of prednisone within 2–3 months), alcohol, coagulation abnormalities, and smoking

      Idiopathic: 10% to 20%

History and physical examination

•  Insidious onset of groin pain with possible radiation to the buttock or knee

•  Physical examination (not specific)

      Pain with hip motion, particularly with internal rotation ± limited ROM

Diagnosis

•  Clinical diagnosis (high index of suspicion) confirmed by imaging finding

•  Differential diagnosis: similar to hip OA

•  Imaging

      Plain radiographs: the Arlet–Ficat staging

  Other criteria (Steinberg/University of Pennsylvania); further grading with A (mild) to C (severe)

      MRI: sensitivity high as 88% to 100%, helpful in early stages and for differential diagnosis

Treatment (59)

•  In early stages of the disease

      Nonoperative treatment, including limited weight bearing and weight bearing with assistance to prevent head deformation and limit pain

      Address underlying coagulation disorder with anticoagulation, bisphosphonates (to prevent resorption of necrotic bone), and statin (hyperlipidemia predispose to osteonecrosis) in patients taking steroids (52)

      Optional surgical treatment: core decompression, 70% to 95% success rate for Stage I

•  Referral to surgery in Stage II or III disease: bone grafting using vascularized fibula. Stage IV: THA

STRESS FRACTURE

Femoral Neck Stress Fracture

Introduction (60)

•  Infrequent (5% of all stress fracture in athletes) but highly morbid condition

•  Classification

      Tension type: superior lateral cortex, distraction by weight-bearing axial force

  Older population, high risk for nonunion and displacement

      Compression type: inner aspect, weight-bearing cause compression, younger population

•  High-complication rates 20% to 86%: complete fracture, malunion with impingement, nonunion, avascular necrosis, and arthritic change

•  Anatomy

      Femoral neck exposed to tensile (superior aspect) and compressive force (inferior aspect)

•  Etiology and risk factors: an intense impact-loading training (young population) or osteoporosis (elderly)

      History of a recent change in activity, duration, or frequency

      Female, hormonal/menstrual disorder, poor nutrition (vitamin D and calcium deficiency), smoking, and other risk factors for osteoporosis

      Biomechanical factors: leg-length discrepancy, coxa vara, pes cavus, worn-out shoe, and so on

      Long-distance runners, ballet dancers, and military personnel

      Training hours: if ≥8 hr/wk two times higher for stress fracture than ≤4 hr/wk in female athletes (61)

History and physical examination

•  Gradual onset of activity-related groin pain, often pain at night

•  Physical examination: not specific

      Pain on extreme range (especially internal rotation), active straight leg raise, log rolling, and hopping

      Usually not tender on palpation

      Fulcrum test

  The patient is seated on the examination table with his lower legs dangling. The examiner places one of his arms under the symptomatic thigh (fulcrum). The arm moves toward the proximal thigh with other hand pushing down the knee. Test is positive if this reproduces pain or discomfort.

      Hop test: reproduction of pain with one-legged hop

Diagnosis

•  Clinical suspicion confirmed by imaging study

•  Imaging

      Plain x-ray: may be normal (can occur without cortical break), a visible fracture line, a visible break in the trabeculae, or callus formation

      MRI: more sensitive and specific; study of choice when plain x-ray is normal in suspicious case and for differential diagnosis

•  Differential diagnosis: other sources of groin pain

Treatment (62,63)

•  Nonoperative treatment for medial side, nondisplaced fracture: 6 weeks weight-bearing restriction with crutches or limited weight bearing for 3 to 6 months

      Bone scan at the end of the treatment (optional): to confirm healing

      Address underlying etiologies: nutritional, footwear, training errors, and/or smoking cessation

•  Referral to surgery for lateral side: because of poor healing (nonunion and AVN), displaced, or diastasis open reduction internal fixation (ORIF)

•  Return to play: asymptomatic full weight bearing, negative physical examination, and imaging study consistent with healed fracture

Pubic Ramus Stress Fracture

Introduction (64)

•  Rare; stress fracture of the pelvis (~1%–2% of all stress fractures)

•  Common in military recruits, and in female runners (in part to increase in female participation in marathon and partly because of anatomical configuration)

•  Common location: inferior ramus because of tensile force (adductor magnus and gracilis pulling on the lateral aspect of the pubis ramus and ischium during hip extension) rather than compressive force

History and physical examination

•  Groin pain worsening with weight bearing (not specific) and nonspecific physical examination

Diagnosis

•  Clinical suspicion confirmed by imaging study

•  Imaging study

      X-ray: 2 to 4 weeks lag and 50% never show any changes in plain film

      MRI rather than bone scan (poor specificity and poor anatomical detail; false positive up to ~30% because of high osteoblastic activity in the area, periosteitis, adductor tendonitis, and avulsion fracture)

•  Differential diagnosis: periosteitis, adductor strain/tendonitis, and avulsion fracture

Treatment

•  Protected weight bearing rather than non–weight bearing (not common)

Femoral Shaft Stress Fracture

Introduction (65)

•  3% to 20% of stress fracture (depending on studies and populations), underrecognized, athletes (proximal femur), and military recruits (distal femur)

•  Common location: proximal one-third, posteromedial cortex by compressive force (medial side greater than lateral side)

History and physical examination

•  Insidious onset of pain, often nonspecific, localized in the groin, thigh, or knee

•  Specific tenderness: less likely given the overlying muscle bulk of the thigh

•  Hop and fulcrum test reproducing pain

Diagnosis

•  Clinical suspicion confirmed by imaging study

•  X-ray (30%–70% positive) and MRI (especially to differentiate neoplasms)

•  Comprehensive assessment of risk factors

•  Differential diagnosis similar to femoral neck fracture

Treatment

•  Relative rest with gradual return to play

      Four phases, each lasting 3 weeks: at the end of the phase, hop and fulcrum test; if negative then advance

  Walk with crutches, non–weight bearing in symptomatic side normal walking, swimming, and exercise upper body and contralateral side partial weight and run in straight line every other day return to play

•  Referral to surgery if displaced or persistent pain despite conservative treatment

OSTEITIS PUBIS

Introduction (66)

•  Chronic, painful injury of pubic symphysis and parasymphyseal bone

•  Common in athletes: 14% of groin pain in athletes (small study), male > female

•  Etiology

      Repetitive trauma, abnormal motion, and subtle pubic instability

  Running, sprinting, soccer, football, and hockey

  Repeated activities of cutting, kicking, and jumping

      Iatrogenic: status post (s/p) urological and obstetrical procedures

History and physical examination

•  Pain in the medial groin (midline) ± referred pain to the medial thigh, abdomen, or perineum

      Pain on striding and pivoting

•  Point tenderness over the pubic symphysis and painful range with passive abduction and resisted adduction

Diagnosis (67)

•  Clinical diagnosis confirmed by imaging study

•  Imaging study

      X-ray: widening of symphysis, sclerosis, cyst, irregularity, and bone resorption

  Flamingo view (stork view) for instability: AP with alternating unilateral lower-extremity weight bearing

           –  Positive if symphysis widens >7 mm or superior ramus displaces >2 mm

      MRI: bone edema (debate regarding clinical significance), secondary cleft sign (abnormal inferior extension of the cleft in the symphyseal fibrocartilage), and to differentiate other pathologies (68)

•  Differential diagnosis

      Adductor tendon dysfunction, injury to the prepubic aponeurotic complex, and sports hernia

      Hip pathology (OA, femoroacetabular impingement), stress fracture, iliopsoas tendon dysfunction, referred pain from lumbar spine or SI joint, rarely direct inguinal hernia, and osteomyelitis

Treatment

•  Nonoperative treatment: biomechanical assessment and improvement of mechanical imbalance and pain medication (NSAIDs) as needed

      PT: water-based exercise initially (if available), stretching exercise of hip adductor, iliopsoas, isometric exercise of abdominal muscle, core, pelvis- and hip-stability exercises

      Steroid injection (small volume), platelet-rich plasma injection, and prolotherapy

•  Surgery is rarely needed

•  Progressive return to sport: up to 3 months

AVULSION FRACTURE AND APOPHYSEAL INJURIES

Introduction (69)

•  Peak incidence in adolescent/young athletes (14–25 years of age) by injury or displacement of unfused apophysis at the site of tendon attachment

•  Etiologies

      Apophyseal injuries: similar to musculotendinous junction injury in mature athletes

      Inherent weakness in the unfused apophyseal growth plate

      Forceful contraction of the muscle; usually associated with jumping, sprinting, or running

  Football and soccer players, cheerleaders, and gymnasts

•  Common locations of apophyseal injuries in adolescents

      Ischium: hamstring, MC location of apophyseal avulsion injury in the pelvis

      ASIS: sartorius and tensor fascia lata; can be confused with anterior inferior iliac spine (AIIS) avulsion fracture if avulsion fragment is retracted distally

      AIIS: rectus femoris

      Iliac crest apophysis: ossification between 15 to 18 years old, abdominal muscles, hip pointers, often bilateral, anterior third of the growth plate of the iliac crest

      Symphysis pubis and inferior pubic ramus: adductor of the hip, associated with overuse injury of excessive twisting and turning of the abdomen and pelvis, athletic pubalgia

      Lesser trochanter: iliopsoas, uncommon, adolescent soccer players before closure of the apophyseal growth plate (28,29)

•  Location in adult avulsion injury

      Adductor insertion avulsion syndrome: at the insertion of adductor longus and brevis (medial thigh), female athletes in track or long-distance running, military recruits

      Abductor tendon avulsion syndrome: elderly >65 years of age, repetitive microtrauma from hyperadduction, falls; usually comes with gluteus tendinopathy or after THA

      Lesser trochanter avulsion: often minimal (not excessive) amount of force in elderly

History and physical examination

•  Pain (sudden onset and severe) at the location of avulsion, difficulty walking ± popping sensation, often not specific, aggravated by activity

•  Tenderness and swelling, pain on stretching of the tendon or muscle involved

      Reproduction of pain with contraction of the muscle involved

Diagnosis

•  Clinical suspicion confirmed by imaging

•  X-ray: often subtle if the displacement is minimal. In chronic cases: extensive callus or new bone production

•  US and MRI if radiographs are indeterminate (minimally displaced or nondisplaced)

      MRI: fluid or edema signal (increased T2 SI) in the growth plate

•  Differential diagnosis: metastatic disease in adults with no significant trauma

Treatment

•  Nonoperative management: rest, return to full weight bearing, and passive ROM exercise, great success with nonoperative management

      In lesser trochanter avulsion in elderly: non–weight bearing with crutches initially for symptomatic treatment

•  Return to play after full strength regained and full ROM without pain

•  Surgery: ORIF in competitive athletes and if avulsed segment >2 cm in diameter. Timing of the surgery: controversial

HIP POINTER

Introduction (30)

•  Iliac crest or surrounding soft tissue contusion, apophyseal injury of iliac crest

•  Common injury in contact sports, football, hockey, and rugby

      11% of total hip injuries and 35% of total hip contusions in National Football League

      MC cause: direct trauma

•  Sequels: if untreated, it can lead to periostitis or the formation of new bone (exostosis)

History and physical examination

•  Pain over the iliac crest or ASIS, difficulty walking ± fluctuating mass (hematoma) ± tingling/pins/needles with irritation of iliohypogastric, ilioinguinal, and lateral femoral cutaneous nerve

•  A fluctuant mass over the area, resulting from hematoma

Diagnosis

•  Clinical diagnosis ± confirmed by imaging study

•  X-ray to R/O fracture or apophyseal avulsion in the skeletally immature patient

Treatment

•  Rest, ice, compression and elevation (RICE), NSAIDs starting at 48 hours. Crutches if gait difficulty present

•  If a large hematoma is present, consider immediate aspiration followed by ice and compression

•  PT for ROM, stretching (TFL, sartorius, abdominal muscle, and iliopsoas), and strengthening

•  Steroid injection to the iliac crest if the pain persists despite PT

•  Return to play if full ROM and full strength achieved. Padding over the injured area to prevent recurrence or exacerbation

HIP DISLOCATION

Introduction (31)

•  Etiology: severe injury from high-energy trauma; motor vehicle accident (MC causes), alpine skiing, football, and wrestling

•  Posterior dislocation: MC, 80% to 85% (posteriorly directed force on flexed knee, dashboard injury)

•  Complications

      Acetabular and femoral head fracture, sciatic nerve injury: 10% to 20% (traction or direct trauma), ligaments injury and other associated fracture

      Long-term complications: AVN (1%–17%), posttraumatic OA

History and physical examination

•  Severe pain, decreased ROM with pain, and difficulty walking/impaired weight bearing

•  Posterior: hip is held in flexion, adduction, and IR

•  Anterior: hip is held in extension, abduction, and external rotation

•  If this injury is suspected, a careful neurological and vascular exam is needed

Diagnosis

•  Clinical diagnosis (high index of suspicion in children and adolescents in subtle cases), confirmed by imaging study

•  AP pelvis and lateral view

•  Investigation for concomitant avulsion of ligament teres, femoral neck fracture, and other lower extremity fracture, intra-abdominal/pelvic injuries, chest trauma, and head injury (concussion)

Treatment

•  Urgent/emergent orthopedic consultation (referral to ER) is recommended

      AVN of the femoral head is directly related to time from dislocation to reduction

      A closed reduction should be attempted only after radiographs have been obtained

TUMOR OR TUMORLIKE LESION

Classification (32)

•  Common osseous tumors

      Primary osseous tumors of the pelvis in decreasing order of frequency; chondrosarcoma, Ewing sarcoma, osteosarcoma, and fibrosarcoma

      Primary benign osseous tumors or pseudotumors of the proximal femur: fibrous dysplasia, solitary bone cyst (proximal humerus > proximal femur), aneurysmal bone cyst (proximal femur), and osteoid osteoma

  Fibrous dysplasia (proximal femur 22%, pelvic 6%, mixed lysis and sclerosis, shepherd’s crook deformity)

•  Tumorlike lesions: trauma, infection, cysts, Langerhans cell histiocytosis, Paget disease (differential diagnosis with diffuse metastatic disease)

Common presentation

•  Usually asymptomatic, rest pain or night pain, systemic symptoms, or palpable mass

•  High index of suspicion with red flags

•  Imaging study: x-ray (often insensitive), then MRI with/without contrast, especially for soft tissue tumors

Pediatric Tumors

Benign tumors: bone cysts, fibrous dysplasia

•  Usually asymptomatic, but mechanical pain if it compromises the structural integrity of the bone

•  Night pain and pain with weight bearing: benign aggressive neoplasms such as osteoid osteoma or chondroblastoma

Leukemia is the most common malignancy in childhood

•  The hip can be the most frequent site of musculoskeletal (MSK) pain (33)

      May present like infectious etiology (septic arthritis or osteomyelitis) initially

•  Labs: elevated ESR with associated anemia, neutropenia, or thrombocytopenia

      Often x-rays are normal, but MRI scans show the marrow replacement

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