AUTHOR AND EDITOR INFORMATION

Section 1 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

INTRODUCTION

Section 2 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Background

Hip and pelvis injuries represent 2-5% of all sports injuries. Among these injuries, groin pain is the most common finding. The most common sports-related injuries in the hip, pelvis, and thigh area are musculotendinous, (eg, quadriceps strain, adductor tendinitis) and, less commonly, iliopsoas tendinitis. Iliopsoas tendinitis and iliopsoas bursitis are closely interrelated because inflammation of one inevitably causes inflammation of the other, due to their close proximity. Therefore, these 2 conditions are essentially identical in terms of presentation and management.

In basic terms, iliopsoas tendonitis is an inflammation of the tendon or area surrounding the tendon. Major causes of iliopsoas tendinitis are acute trauma and overuse resulting from repetitive hip flexion.

Frequency

United States

No data on prevalence of iliopsoas tendinitis exists. Despite this, it is a relatively uncommon and poorly recognized cause of anterior hip or groin pain. Iliopsoas tendinitis is noted to affect young adults more commonly, with a slight female predominance.

Functional Anatomy

The pelvis links the trunk and lower extremities. The hip, a ball and socket joint, allows for 3 degrees of freedom. Range of motion (ROM) of the hip includes approximately 120° of flexion, 20° of extension, 40° of abduction, 25° of adduction, and 45° each of internal rotation and external rotation. The resting position of the hip is considered to be 30° of flexion and 30° of abduction.

The psoas and iliacus muscles originate from the lumbar spine and pelvis, respectively, and are innervated by the upper lumbar nerve roots (ie, L1, L2, L3). These muscles converge to form the iliopsoas muscle, which inserts onto the lesser trochanter of the proximal femur as the iliopsoas tendon. The psoas major tendon exhibits a characteristic rotation through its course, transforming its ventral surface into a medial surface. The iliac portion of this tendon has a more lateral position, and the most lateral muscle fibers of the iliacus muscle insert onto the lesser trochanter without joining the main tendon.

The iliopsoas muscle passes anterior to the pelvic brim and hip capsule in a groove between the anterior inferior iliac spine laterally and iliopectineal eminence medially. The musculotendinous junction is consistently found at the level of this groove. The iliopsoas muscle functions as a hip flexor and external rotator of the femur.
 
An ilio-infratrochanteric muscular bundle has been described, which likely relates to the iliopsoas tendon. This muscular bundle arises from the interspinous incisure and anterior inferior iliac spine (above the origin of the rectus femoris muscle), courses along the anterolateral edge of the iliacus muscle, and inserts without a tendon onto the anterior surface of the lesser trochanter. The iliopsoas bursa lies between the musculotendinous junction and the pelvic brim. This bursa is the largest in the body and may extend proximally into the iliac fossa or distally to the lesser trochanter. Communication between this bursa and the hip joint occurs in approximately 15% of all adults.

A variety of terms have been used to describe and classify tendon injuries. Tendonitis is typically associated with an acute injury through which failure of the tendon fibers and disruption of the vascularized peritendinous connective tissue produces an acute inflammatory response within the tendon. Tendinitis may be acute, subacute, or chronic, depending on the duration of symptoms.

Peritendinitis is a condition in which an acute injury produces an inflammatory response in only the soft tissue surrounding a tendon, without disruption of the tendon fibers. On the other hand, tendinosis is often associated with chronic microtrauma to the tendon, such as repetitive overload. In the case of tendinosis, fiber failure tends to be characterized by intrasubstance failure, compared with peritendinous disruption, which occurs in tendinitis. Microscopic findings in tendinosis include fibrillar degeneration, angiofibroblastic proliferation, myxoid degeneration, fibrosis, and, occasionally, chronic inflammation.

Sport Specific Biomechanics

Acute injury and overuse injury are the 2 main causes of iliopsoas tendinitis. The acute injury typically involves an eccentric contraction of the iliopsoas muscle, but also may be due to direct trauma. Overuse injury may occur in activities involving repeated hip flexion or external rotation of the thigh. Activities that may predispose to iliopsoas tendinitis include dancing, ballet, resistance training, rowing, running (particularly uphill), track and field, soccer, and gymnastics.

During the adolescent growth spurt, the hip flexors tend to become relatively inflexible. This inflexibility can lead to problems in younger athletes because stress placed on the iliopsoas musculotendinous unit increases and general biomechanics are altered. Tightness of the iliopsoas, tensor fascia lata, or rectus femoris can lead to inhibition of the gluteus maximus, allowing for an anterior pelvic tilt. This in turn leads to adverse affects on the kinetic chain. Excessive anterior tilt can lead to increased lumbar lordosis with resultant stress on the lower lumbar discs, facet joints, and sacroiliac joints and may result in increased knee flexion at heel strike and during midstance phases of the gait cycle. The subsequent increase in eccentric load across the knee extensor mechanism may result in patellar tendon injuries. With increased knee flexion, compressive forces at the patellofemoral contact surface increase and may predispose to patellofemoral problems.

CLINICAL

Section 3 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

History

Patients often present with complaints of an insidious onset of anterior hip or groin pain. As in other cases of tendinitis, initially the patient may note pain after onset of aggravating activity with resolution soon thereafter. This condition may progress to pain that persists during activity but subsides with rest, and eventually to pain during activity and at rest. The average time from initial onset of symptoms to diagnosis has been noted to range from 32-41 months.

• At presentation, patients may note pain with specific sports-related activities, such as jogging, running, or kicking. Pain with simple activities, such as putting on socks and shoes, rising from a seated position with the hips flexed for some time, walking up stairs or inclines, or brisk walking may be reported.
• Pain may radiate down the anterior thigh toward the knee.
• Reports of an audible snap or click in the hip or groin commonly are reported and associated with internal snapping hip syndrome.
• Patients may report anterior knee pain consistent with patellar tendinitis or patellofemoral dysfunction, which may be the result of a tight iliopsoas muscle.

Physical

Physical examination should focus on complete examination of the abdomen, hip, and groin. In females, a complete pelvic examination also should be considered.

• Inspection
• • The hip may be held in slight flexion and external rotation to ease tension on the musculotendinous unit.
  
  
  
  • Gait may demonstrate a shortened stride length on the affected side and increased knee flexion in the heel strike and midstance phases.
     
• Palpation
• • An anterior pelvic tilt may be appreciated due to subsequent tightening of the iliopsoas muscle.
  
  
  
  • Direct deep palpation to the area of the femoral triangle, which is bordered superiorly by the ilioinguinal ligament, medially by the adductor longus muscle, and laterally by the sartorius muscle, results in direct palpation of the iliopsoas musculotendinous junction.
  
  
  
  • Tenderness over the iliopsoas tendon's insertion may be noted by palpating the lesser trochanter under the gluteal fold with the patient lying in a prone position.
     
• Functional testing
• • Functional testing includes resisted hip flexion at 15° with palpation of the psoas muscle below the lateral half of the inguinal ligament.
  
  
  
  • The patient also may be asked to sit with knees extended and subsequent elevation of the heel on the affected side. Pain caused by this maneuver (a positive Ludloff sign) is consistent with an iliopsoas tendinitis because the iliopsoas is the sole hip flexor activated in this position.
  
  
  
  • The snapping hip sign or extension test also may be performed. Start with the affected hip in a flexed, abducted, and externally rotated position (knee is flexed for ease of testing), and passively move the hip into extension. This may result in an audible snap or palpable impulse over the inguinal region. Pain associated with this maneuver is highly suggestive of iliopsoas tendinitis or bursitis.

Causes

The 2 most common causes of iliopsoas tendinitis are acute injury and overuse injury. The acute injury often involves eccentric contraction of the iliopsoas muscle or rapid flexion against extension force/resistance but may less commonly result from direct trauma. The overuse phenomenon may occur in any activity resulting in repeated hip flexion or external rotation of the femur.

• Among dancers, a narrow bi-iliac width, greater abduction, decreased lateral rotation, and greater strength in the lateral rotators have been described more commonly with snapping hip syndrome, which is related to iliopsoas tendinitis.



• Rheumatoid arthritis may be a cause of iliopsoas bursitis.

DIFFERENTIALS

Section 4 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Other Problems to be Considered

Appendicitis (right groin)
Arthritis
Avulsion of the lesser trochanter
Chondral defect
Gynecologic pathology
Hernia
Intra-articular loose bodies
Labral Tear
Obturator nerve entrapment
Pelvic stress fracture
Synovitis

WORKUP

Section 5 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Lab Studies

• Laboratory studies rarely are indicated if diagnosis of iliopsoas tendinitis is certain.



• If the diagnosis is unclear, a CBC count, erythrocyte sedimentation rate or C-reactive protein, rheumatoid factor, anticyclic citrullinated peptide antibody, antinuclear antibody, and urinalysis are helpful ancillary tests for distinguishing among several other causes of groin pain.

Imaging Studies

• Plain radiographs
• • Hip radiographs often are the initial imaging study obtained because diagnosis of iliopsoas tendinitis may not be demonstrated clearly.
  
  
  
  • A pelvic anteroposterior radiograph and frog leg lateral radiograph of the affected hip often are adequate initial studies.
  
  
  
  • Radiographs typically are normal in cases of iliopsoas tendinitis, but may demonstrate other bony pathology, which may contribute to the patient's symptom complex.
     
• Ultrasonography
• • Ultrasonography has been used more frequently as a noninvasive diagnostic adjunct in the diagnosis of muscle-tendon injuries. Demonstration of a thickened tendon is the usual finding.
  
  
  
  • Ultrasonography may demonstrate an excessive amount of fluid in the iliopsoas bursa consistent with iliopsoas bursitis, which may be either a primary or secondary problem.
  
  
  
  • Remember that ultrasonography is highly user-dependent and may not be the optimal test at institutions with personnel who are unfamiliar with ultrasonography use for this type of examination.
     
• MRI
• • MRI currently is the criterion standard in the ancillary evaluation of painful conditions of the hip and pelvis, particularly because many anatomical structures may be the origin of the pain. In a recent study of 19 endurance athletes with groin pain and an established clinical diagnosis, MRI was shown to reclassify 32% of the hips to a different etiology for the groin pain. These diagnoses included iliopsoas muscle tears and iliopsoas tendinitis.
  
  
  • In evaluating musculotendinous injury, the spin-echo T2-weighted images demonstrate increased signal intensity associated with swelling and inflammation. However, in hemorrhage associated with a more severe musculotendinous injury, both the T1-weighted images and T2-weighted images depict a high-signal intensity.
  
  
  
  • In peritendinitis evaluation, increased fluid in the peritendinous tissue is detected on the spin-echo T2-weighted images or short T1 inversion recovery (STIR) sequence as a focus of high-signal intensity surrounding a normal tendon.
  
  
  
  • On the other hand, tendinosis is demonstrated on the spin-echo T1-weighted images as an area of higher signal intensity within the tendon associated with myxoid degeneration or angiofibroblastic proliferation. The spin-echo T2-weighted images may show an abnormal signal (usually less than that seen on the T1-weighted images) or a normal signal.

Procedures

• Lidocaine challenge test
• • Lidocaine challenge test may be performed in a challenging case of iliopsoas tendinitis where cause of pain is unclear.
  
  
  
  • Utilizing an anterior approach through the femoral triangle, and under ultrasonographic guidance, an interventional radiologist or orthopedic surgeon attempts to bath the iliopsoas tendon with 1% lidocaine. In general, 10 mL of lidocaine administered via a 25-gauge spinal needle is adequate for local anesthesia.
  
  
  
  • Relief of symptoms after injection confirms diagnosis.

TREATMENT

Section 6 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Acute Phase

Rehabilitation Program

Physical Therapy

The primary objective of the acute rehabilitation phase is to alleviate pain, spasm, and swelling. A secondary issue, if necessary, is to return the patient to activities of daily living (eg, walking unassisted). A combination of medication, ice, rest, and gentle stretching assists these goals in coming to fruition. A pack of crushed ice in a damp cloth-covered ice bag applied for 20 minutes every 1-2 hours also can provide the patient with relief of pain, spasm, and inflammation.

In addition to relative rest (avoidance of activities that stress the iliopsoas muscle), a gentle stretching regimen can assist in reduction of spasm in the iliopsoas complex. Note that stretching must not immediately follow icing, when the sensitivity to pain is lessened, because a potential to overstretch exists. A gentle stretch for the iliopsoas muscle is demonstrated in Media File 1. Hold the stretch for a count of 20 seconds, relax for 30 seconds, and repeat the stretch 5 times. Caution patients to not hold their breath while maintaining a pain-free stretch.

If a normal gait is not present at the time of diagnosis, the patient needs to begin ambulation exercises with the assistance of crutches, gradually moving to partial weight bearing, progressing to full weight bearing, and, finally, walking without an antalgic gait and without assistance. The patient can practice walking in front of a full-length mirror to ensure that ambulatory rhythm and techniques are correct.

Medical Issues/Complications

The average time from onset of symptoms to diagnosis typically ranges from months to years; therefore, most patients may present in the subacute or chronic phases of the condition. Despite this, medical treatment during the acute phase consists of relative rest and avoidance of activities that cause pain. Rarely, crutches may be necessary if sufficient pain is associated with ambulation or activities of daily living. The application of ice for 20 minutes every 1-2 hours for the first 1-3 days is recommended in addition to a short course (eg, 5-14 d) of nonsteroidal anti-inflammatory drugs (NSAIDs) in order to potentially limit inflammation and assist with analgesia.

Recovery Phase

Rehabilitation Program

Physical Therapy

The purpose of this rehabilitation phase is to return the patient to normal ROM, strength, endurance, and activity specific to the patient’s sport. Normal ROM can be accomplished by sustaining normal gait mechanics, maintaining a stretching regimen, and practicing good warm-up and cool-down techniques with exercise.

Stretching exercises that facilitate full ROM for the iliopsoas complex are demonstrated in Media Files 1-2. In addition to stretching for ROM, certain stretches can allow an anteriorly over-rotated pelvis to return to a more anatomical position. Stretching the rectus femoris (see Media File 3) promotes a neutral pelvic position and diminishes strain or spasm of the iliopsoas muscles. Instruct patients to hold the stretch as instructed in the Acute Phase of physical therapy.

In addition to stretching for return of normal pelvic alignment, strengthening the hamstrings provides a posterior force on the pelvic girdle and combats the stress of the iliopsoas pull on the anterior pelvis. See Media Files 5-8. Iliopsoas muscle injury can cause lumbar lordosis and anterior pelvic tilt, both of which can be corrected by strengthening specific counteracting muscle groups.

Strengthening the abdominal musculature by performing sit-ups addresses both issues. Sit-ups performed by hooking ankles under an object or having them held fast can aggravate the lumbar lordosis and iliopsoas strain. Sit-ups or crunches executed with knees and hips flexed at 90° allows the iliopsoas to relax, with the effort concentrated on the rectus abdominus muscle, and preserves a neutral pelvic position (see Media File 9). Exercises that strengthen the gluteus maximus also augment the ideal pelvic status (see Media File 10).

Begin all strengthening exercises at a weight that the patient can comfortably lift or with an elastic band resistive device with which the patient controls the tension. Exercises should be pain-free and performed daily in 4 sets of 10-15 repetitions. As the weight becomes easier to lift, increase the resistance.

Endurance is gained through movement with low resistance over time. Exercises requiring repeated hip flexion or femoral external rotation can improve iliopsoas function if resistance is low. Examples of these exercises are cycling with low resistance, stair climbing on a machine with the setting on the lowest resistance, or walking. The workout should not produce pain but could fatigue the iliopsoas muscle. Use caution so that the musculature has time to recuperate prior to the next bout of endurance training. As the muscle recovers, endurance exercises can be performed daily, and resistance gradually can be increased with time of activity.

Recreational Therapy

As tolerance to activity increases, the patient can begin easy resistance cycling, walking, and jogging (without terrain). In the recovery phase, the patient intends to gradually return to sport-specific activities, leading to full pain-free participation.

Medical Issues/Complications

Intermittent episodes of pain may be experienced as the patient slowly starts to return to the activities of daily living and progresses in the strengthening program. At these times, short courses of analgesics may be required, in addition to activity modification.

Surgical Intervention

Surgical intervention is not commonly used for iliopsoas tendinitis; however, it is considered for those patients in whom typically prolonged nonsurgical management and a lidocaine injection trial fail.

The 2 surgical techniques that have been described are (1) complete release of the iliopsoas tendon and (2) partial release by transection of the posteromedial aspect of the iliopsoas tendon. Each approach has produced generally good results in terms of pain relief, with little documentation of significant residual weakness. Gruen et al reported 73% of patients returned to previous athletic activities, with 45% also returning to their previous level of athletic participation following surgery. Hoskins et al reviewed their experience with surgical correction by iliopsoas tendon fractional lengthening in 92 cases. Complications were noted in one third of patients and mostly included persistent hip pain, sensory deficits, and hip flexor weakness.

Dobbs et al recently reported outcomes for surgical fractional lengthening of the iliopsoas tendon in adolescents (mean age 15 y). At 4-year mean follow-up, all patients had returned to their preoperative level of activity without subjective weakness.

More recently, Byrd et al described releasing the iliopsoas tendon arthroscopically.

Consultations

Peritendinous injections generally are performed by either an interventional radiologist or orthopedic surgeon. For physicians unfamiliar with diagnosis and management of iliopsoas tendinitis/bursitis, a referral to primary care sports medicine, orthopedic surgery, or physiatry is appropriate.

Other Treatment (injection, manipulation, etc)

A peritendinous corticosteroid injection may be performed under ultrasonographic guidance with a combination of a local anesthetic (eg, 1% lidocaine) and a corticosteroid (eg, betamethasone, triamcinolone).

Maintenance Phase

Rehabilitation Program

Physical Therapy

The goal of the maintenance phase of rehabilitation for iliopsoas injury is to challenge the muscles involved to continue to perform their work. Stretching the iliopsoas and rectus femoris must continue (see Media Files 1-3), and strengthening should be increased to meet the demands of the recovered iliopsoas and perform at an optimal level. Exercises moving away from those depicted in the Recovery Phase can be initiated in a gym, although the same results can occur by gradually increasing resistance to the exercises in Media Files 5-8.

Refer to Media Files 11-13 for demonstrations of advanced strengthening exercises for the iliopsoas and hamstrings. These pain-free exercises should gradually progress in resistance by increasing either the repetitions or weight every third or fourth workout, as tolerated. The advanced move of the lunge (see Media File 14) allows for many muscles (ie, iliopsoas, hamstrings, gluteus maximus, groin) to work together to return strength and balance to the athlete. Lunges are intended to be slow gentle exercises, with fluid movement as the back knee lowers toward the ground. This position is held for 5-7 seconds prior to returning to a more upright position to end the exercise.

Recreational Therapy

Recreational activities that facilitate the recovered iliopsoas muscle to maintain its strength and function include rollerblading, cycling, dancing, skating, horseback riding (especially English riding), and rowing. Other sports, such as soccer, competitive cycling, running, and gymnastics, all have a high demand of hip flexion combined with trunk flexion, which shortens the iliopsoas and can cause stress when the body demands hip flexion independent of trunk flexion. Maintaining a stretching and strengthening program is crucial and the patient should consider cross-training for lower extremity sports that allow for a more upright trunk.

MEDICATION

Section 7 of 11  

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• Miscellaneous
• Multimedia
• References

The drugs of choice for treatment of iliopsoas tendonitis and most other tendinopathies are NSAIDs. This class of drugs provides good analgesia and possible anti-inflammatory properties.

Drug Category: Nonsteroidal anti-inflammatory drugs (NSAIDs)

This class of drugs has analgesic and antipyretic activities and possibly also anti-inflammatory activities. Their mechanism of action is not known, but they may inhibit COX activity and prostaglandin synthesis. Other mechanisms may also exist, such as inhibition of leukotriene synthesis, lysosomal enzyme release, lipoxygenase activity, neutrophil aggregation, and various cell membrane functions.

Drug Category: Cyclooxygenase-2 (COX-2) inhibitors

Cox-2 inhibitors operate as non-steroidal anti-inflammatory drugs with the potential for less fatal GI bleeding due to ulceration and possibly enhanced analgesic properties. Ongoing analysis of cost avoidance of GI bleeds will further define the populations that will find COX-2 inhibitors the most beneficial.

Drug Category: Analgesics

Useful for patients in whom NSAIDs are contraindicated. Analgesics are potentially useful for patients who require a more prolonged use of analgesics.

FOLLOW-UP

Section 8 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Return to Play

Return to play is allowed once the patient is free of pain and has demonstrated adequate flexibility and strength of the hip flexors and antagonist muscle groups. Performance of pain-free, sports-specific activities should be required.

Complications

Recurrence of tendinitis is a potential complication. Possibility of residual weakness in individuals selected to receive surgical management is another potential complication.

Prevention

As in most cases of musculotendinous injury, the best prevention is a focused flexibility and strengthening program, which should include, at a minimum, the hip flexors, hip extensors, knee flexors, knee extensors, and abdominal musculature.

Education

For excellent patient education resources, visit eMedicine's Foot, Ankle, Knee, and Hip Center, Sports Injury Center, and Arthritis Center. Also, see eMedicine's patient education articles Tendinitis and Bursitis.

MISCELLANEOUS

Section 9 of 11  

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• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Medical/Legal Pitfalls

• The primary complication in treatment and management of an iliopsoas tendinitis is misdiagnosis and failure to consider other, more urgent causes of groin pain in the athlete. Remembering to include a full abdominal, groin, pelvic, and neurological examination on all patients should help to avoid this pitfall.

MULTIMEDIA

Section 10 of 11  

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• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Media file 1:  Iliopsoas stretch.
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Media file 2:  Iliopsoas stretch in external rotation.
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Media file 3:  Rectus femoris stretch.
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Media file 4:  Hamstring curl with cuff weight for strengthening.
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Media file 5:  Iliopsoas strengthening with cuff weight.
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Media file 6:  Hip flexion (straight-leg raising) strengthening with cuff weight.
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Media file 7:  External rotation strengthening with cuff weight.
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Media file 8:  External rotation strengthening with elastic band resistive device.
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Media file 9:  Sit-ups with hips and knees in 90° of flexion.
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Media file 10:  Standing hip extension strengthening with elastic band resistive device.
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Media file 11:  Four-way hip marching (standing hip flexion).
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Media file 12:  Prone hamstring curls.
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Media file 13:  Seated hamstring curls.
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Media file 14:  Lunges.
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REFERENCES

Section 11 of 11

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

• Byrd JW. Hip arthroscopy. J Am Acad Orthop Surg. Jul 2006;14(7):433-44. [Medline].
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• Dobbs MB, Gordon JE, Luhmann SJ, Szymanski DA, Schoenecker PL. Surgical correction of the snapping iliopsoas tendon in adolescents. J Bone Joint Surg Am. Mar 2002;84-A(3):420-4. [Medline].
• Fredberg U, Hansen LB. Ultrasound in the diagnosis and treatment of iliopsoas tendinitis: a case report. Scand J Med Sci Sports. Dec 1995;5(6):369-70. [Medline].
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• Geraci MC. Rehabilitation of the hip, pelvis, and thigh. In: Kibler WB, Herring SA, Press JM, eds. Functional Rehabilitation of Sports and Musculoskeletal Injuries. Philadelphia, Pa: Lippincott Williams & Wilkins; 1998:226-243.
• Gruen GS, Scioscia TN, Lowenstein JE. The surgical treatment of internal snapping hip. Am J Sports Med. Jul-Aug 2002;30(4):607-13. [Medline].
• Hoskins JS, Burd TA, Allen WC. Surgical correction of internal coxa saltans: a 20-year consecutive study. Am J Sports Med. Jun 2004;32(4):998-1001. [Medline].
• Jacobs M, Young R. Snapping hip phenomenon among dancers. Am Correct Ther J. May-Jun 1978;32(3):92-8. [Medline].
• Jacobson T, Allen WC. Surgical correction of the snapping iliopsoas tendon. Am J Sports Med. Sep-Oct 1990;18(5):470-4. [Medline].
• Janzen DL, Partridge E, Logan PM, Connell DG, Duncan CP. The snapping hip: clinical and imaging findings in transient subluxation ofthe iliopsoas tendon. Can Assoc Radiol J. Jun 1996;47(3):202-8. [Medline].
• Johnston CA, Wiley JP, Lindsay DM, Wiseman DA. Iliopsoas bursitis and tendinitis. A review. Sports Med. Apr 1998;25(4):271-83. [Medline].
• Khan K, Cook JL, Maffulli N. Tendinopathy in the active person: Separating fact from fiction to improve clinical management. Am J Med Sports. 2000;2(2):89-99.
• Reid DC. Prevention of hip and knee injuries in ballet dancers. Sports Med. Nov 1988;6(5):295-307. [Medline].
• Renström P, Peterson L. Groin injuries in athletes. Br J Sports Med. Mar 1980;14(1):30-6. [Medline].
• Shin AY, Morin WD, Gorman JD, Jones SB, Lapinsky AS. The superiority of magnetic resonance imaging in differentiating the causeof hip pain in endurance athletes. Am J Sports Med. Mar-Apr 1996;24(2):168-76. [Medline].
• Tatu L, Parratte B, Vuillier F, Diop M, Monnier G. Descriptive anatomy of the femoral portion of the iliopsoas muscle. Anatomicalbasis of anterior snapping of the hip. Surg Radiol Anat. 2001;23(6):371-4. [Medline].
• Taylor GR, Clarke NM. Surgical release of the 'snapping iliopsoas tendon'. J Bone Joint Surg Br. Nov 1995;77(6):881-3. [Medline].

Article Last Updated: Aug 29, 2006