J. W. Thomas Byrd and MaCalus V. Hogan
DEFINITION
Coxa saltans is a term popularized by Allen and various coauthors.1
Initially they described an internal type (iliopsoas tendon) and an external type (iliotibial band).
More recently, they proposed an intra-articular type, which is simply a catch-all for numerous intra-articular lesions.
Snapping hip syndrome most clearly represents an extraarticular dynamic tendinous phenomenon of either the iliopsoas tendon or iliotibial band.
ANATOMY
The iliopsoas complex, a powerful hip flexor, is formed from the psoas major and iliacus muscles (FIG 1A).
The psoas major originates from the lumbar transverse processes and the sides of the vertebral bodies and intervertebral discs from T12 to L5; the iliacus originates from the superior two thirds of the iliac fossa, the sacral ala, and the anterior sacroiliac ligaments.
The tendon forms first from the psoas proximal to the inguinal ligament and then rotates such that its anterior surface comes to lie medial and its posterior surface lateral.
The tendon then spreads out to insert over the lesser trochanter.
It is joined by an accessory tendon from the iliacus, and the tendons then fuse together before forming the enthesis of the iliopsoas. Some muscle fibers of the iliacus remain separate, attaching directly to bone.
In the sagittal plane, as the iliopsoas exits the pelvis, it is redirected 40 to 45 degrees over the pectineal eminence toward its insertion site.
Iliotibial band (FIG 1B): The fascia lata covers the entire hip region, encasing its three superficial muscles, ie, the tensor fascia lata, sartorius, and gluteus maximus.
A confluence of the tensor fascia lata and gluteus maximus forms the iliotibial band.
The gluteus maximus also partly inserts into the proximal femur at the gluteal tuberosity.
This fibromuscular sheath was described by Henry7 as the “pelvic deltoid,” reflecting on the fashion in which it covers the hip, much as the deltoid muscle covers the shoulder.
PATHOGENESIS
The snapping occurs as the iliopsoas tendon subluxes from lateral to medial while the hip is brought from a flexed abducted, externally rotated position into extension with internal rotation (FIG 2A,B).
It is variously proposed that the anterior aspect of the femoral head and capsule, or pectineal eminence, is responsible for transiently impeding the tendon and creating the snapping.
FIG 1 • A. Depicted on the right, the proximal portion of the iliospoas has been cut away, revealing the lumbar plexus, embedded in its posterior portion. Distally, the femoral neurovascular structures are noted coursing over the iliospoas, which forms the lateral floor of the femoral triangle. On the left, the tendon is formed first from the psoas, which is then joined by the iliacus prior to its insertion on to the lesser trochanter. B. Superficial muscle layer of the hip. (A: Courtesy of J. W. Thomas Byrd, MD; B: Courtesy of Delilah Cohn.)
FIG 2 • The iliopsoas tendon flipping back and forth across the anterior hip and pectineal eminence. A. With flexion of the hip, the iliospoas tendon lies lateral to the center of the femoral head. B. With extension of the hip, the iliospoas shifts medial to the center of the femoral head. C. As the iliotibial band snaps back and forth across the greater trochanter, the tendinous portion may flip across the trochanter with flexion and extension, or the trochanter may move back and forth underneath the stationary tendon with internal and external rotation. (Courtesy of J. W. Thomas Byrd, MD.)
Incidental asymptomatic snapping of the iliopsoas tendon is estimated to be present in at least 10% of a normal, active population.
Painful snapping may be precipitated by macrotrauma or repetitive microtrauma in patients with a predilection for certain activities such as ballet.
The exact structural alteration that occurs when symptomatic snapping develops has not been defined.
The snapping occurs as the iliotibial band flips back and forth across the greater trochanter, and often is attributed to a thickening of the posterior part of the iliotibial tract or anterior border of the gluteus medius (FIG 2C).
The thickened portion lies posterior to the trochanter in extension and flips forward as the hip begins to flex.
Coxa vara and reduced bi-iliac width have been proposed as predisposing anatomic factors.
Tightness of the iliotibial band also may be an exacerbating factor.
Like snapping of the iliopsoas tendon, snapping of the iliotibial band may be an incidental finding without precipitating cause or symptoms.
Painful snapping may occur following trauma, but is more commonly associated with repetitive activities, classically being described in the downhill leg of runners training on a sloped roadside surface.
It also has been reported as an iatrogenic process following surgical procedures that leave the greater trochanter more prominent, or reconstructive procedures around the knee that alter the iliotibial band.
NATURAL HISTORY
For most people, the snapping hip remains asymptomatic, never requiring treatment.
In patients in whom the snapping hip is symptomatic, the course is variable, but there are no apparent long-term consequences of a chronic snapping hip.
Spontaneous resolution may occur but is uncommon.
PATIENT HISTORY AND PHYSICAL FINDINGS
Iliopsoas Tendon
The history of onset of symptoms is variable and may be insidious, owing to specific repetitive maneuvers or an acute injury.
The patient typically describes a clicking sensation emanating from deep within the anterior groin, which often is audible enough to be characterized as a “clunk.”
Although the symptoms typically are referred to the anterior groin, some patients may describe flank or sacroiliac discomfort, reflecting irritation around the origin of the psoas and iliacus muscles.
The characteristic examination maneuver is performed with the patient lying supine, bringing the hip from a flexed, abducted, externally rotated position down into extension with internal rotation, creating the snap.
Sometimes this is a dynamic process that the patient can demonstrate actively better than the examiner can produce passively. Although often prominent, it may be subtle, and may occur more as a sensation experienced by the patient rather than one that the examiner can observe objectively.
Applying pressure over the anterior joint can block the tendon from snapping and assist in confirming the diagnosis.
Variously, patients may be able to demonstrate this best lying, sitting, or standing, or with walking. However, regardless of the position, the snapping uniformly occurs as the hip goes from a flexed toward an extended position.
Iliotibial Band
As with the iliopsoas tendon, patients may describe the onset of symptoms as being insidious, due to specific repetitive activities, or in response to acute trauma.
Whereas snapping of the iliopsoas tendon often can be heard from across the room, snapping of the iliotibial band can be seen from across the room.
Patients describe a sense that the hip is subluxing or dislocating. This is termed “pseudosubluxation,” because the visual appearance may suggest that the hip is subluxing but radiographs uniformly demonstrate that the hip remains concentrically reduced.
The patient always relates a snapping or subluxation-type sensation. The symptoms are located laterally, and patients typically can illustrate this while standing.
As with the iliopsoas, this often is a dynamic process, better demonstrated by the patient than produced by passive examination. It may be detected with the patient lying on the side and then passively flexing and extending the hip.
The snap can be palpated over the greater trochanter, and its origin is confirmed by applying pressure, which can block the snap from occurring.
The Ober test evaluates for tightness of the iliotibial band, which may accompany symptomatic snapping.
IMAGING AND OTHER DIAGNOSTIC STUDIES
The diagnosis of a snapping iliopsoas tendon is based primarily on the history and physical examination.
Iliopsoas bursography and ultrasonography may be helpful to rule in, but not rule out, the diagnosis (FIG 3).
These imaging modalities are technically limited because of a significant rate of false-negative interpretation.
Similarly, snapping of the iliotibial band is based on the clinical assessment, and investigative studies offer little aid in substantiating or discounting the diagnosis.
Nonetheless, plain radiographs remain an essential tool in the assessment of any hip problem, and other investigative studies such as MRI and magnetic resonance arthrography may be important to evaluate for associated conditions such as intra-articular pathology.
DIFFERENTIAL DIAGNOSIS
Snapping iliotibial band
Hip instability
Snapping iliopsoas tendon
Intra-articular pathology
Pelvic instability (eg, sacroiliac joint or symphysis pubis)
Osteochondroma
NONOPERATIVE MANAGEMENT
Treatment often involves little more than establishing the diagnosis and assuring the patient that the snapping is not harmful or indicative of future problems.
Oral anti-inflammatory medications may be helpful in addition to a flexibility and stabilization exercise program.
For recalcitrant cases:
A period of activity modification to diminish symptoms may be necessary.
Judicious use of corticosteroid injections may be appropriate, with the goal of providing transient improvement to supplement the effect of other therapeutic modalities.
SURGICAL MANAGEMENT
Iliopsoas Tendon
Various open procedures have been described for releasing the tendinous portion of the iliopsoas, with generally favorable results.1,5,6,12
However, superior results have been reported with endoscopic methods.4,9 These superior results are due only partly to the less invasive nature of the technique.
Most cases with a painful snapping iliopsoas tendon also were found to have associated intra-articular pathology, which also was addressed.
FIG 3 • Iliopsoas bursography silhouettes the iliopsoas tendon (arrows) with contrast. A. In flexion, the iliopsoas tendon lies lateral to the femoral head. B. In extension, the iliopsoas tendon moves medial. (Courtesy of J. W. Thomas Byrd, MD.)
Failure to inspect the interior of the hip joint and address associated pathology may be a significant contributing factor to less optimal results with traditional open techniques.
Iliotibial Band
Various techniques have been described for correcting snapping of the iliotibial band.
One complex procedure is a Z-plasty lengthening, the results of which have ranged from poor to good.2,10,11
Several techniques have employed a simpler approach, creating a relaxing incision in the portion of the iliotibial band over the greater trochanter, and these have shown to be effective at eliminating the snapping in most cases.3,15Violation of the tendon structure is minimized, which diminishes the morbidity of the procedure and facilitates the postoperative recovery.
Endoscopic methods have been developed that may accomplish this same goal.8
Preoperative Planning
Clinical assessment of the snapping iliopsoas tendon and iliotibial band is relatively straightforward.
However, careful assessment is necessary to ensure that the snapping is clearly the source of the patient's symptoms and also to evaluate other associated conditions, especially concomitant intra-articular pathology.
Perhaps most important is a careful assessment of the patient's motivation, understanding, and goals of recovery.
It is important to bear in mind that coxa saltans often is encountered in asymptomatic individuals.
Surgery is considered only if the patient has exhausted efforts at conservative treatment and demonstrates sufficient motivation for the postoperative recovery.
Positioning
Iliopsoas tendo.
Endoscopic release of the iliopsoas tendon is performed in conjunction with routine arthroscopy of the joint.
Arthroscopy can be performed with the patient in either the supine or lateral position.
The supine position may provide better access to these structures, and is the method described.
Iliotibial ban.
Open procedures employ the lateral decubitus position, and this also has been the preferred orientation for endoscopic methods.
Approach
Iliopsoas tendo.
Most endoscopic reports have described releasing the tendon from its insertion on the lesser trochanter within the iliopsoas bursa.4,9
This is the endoscopic counterpart to the open method described by Taylor and Clarke.12 For the occasional case of a snapping iliopsoas tendon associated with a total hip arthroplasty, it clearly is the preferred approach.
Another endoscopic technique, in which the iliopsoas tendon is approached from the peripheral compartment, seems to provide a comparable effect of releasing the tendon.14 The method is analogous to the open method described by Allen et al.1 Theoretically, it may have an advantage of reduced morbidity.
Iliotibial ban.
The various open approaches use a common, lateral, longitudinal incision over the greater trochanter.
Endoscopic methods employ laterally based portals, approaching the tendon from its superficial subcutaneous surface.
TECHNIQUES
ENDOSCOPIC ILIOPSOAS RELEASE
Lesser Trochanter (Iliopsoas Bursa)
After completing routine hip arthroscopy, including intra-articular and peripheral compartments, the leg is repositioned in 20 degrees of flexion and full external rotation.
Slight flexion partially relaxes the tendon but maintains some tension.
External rotation brings the lesser trochanter more anterior for access from the laterally based portals (TECH FIG 1A).
A portal is established distal to the standard anterolateral hip portal at the level of the lesser trochanter, using fluoroscopic guidance (TECH FIG 1B).
This exposes the tendon within the iliopsoas bursa, which is the largest bursa in the body.
Another portal is then placed distally, converging toward the lesser trochanter (TECH FIG 1C).
The arthroscope and instruments are switched between these two portals for thorough visualization and instrumentation of the iliopsoas tendon (TECH FIG 1D).
Adhesions within the bursa can be cleared, providing excellent visualization of the iliopsoas tendon.
The tendinous portion of the iliopsoas is transected adjacent to its insertion on the lesser trochanter.
This is facilitated with the use of a flexible radiofrequency device.
For safest technique, the medial side of the tendon is fully visualized, and the tendon is then released from medial to lateral. Its fibers will separate 1 to 2 cm.
Muscular attachments of the iliacus muscle are preserved.
Peripheral Compartment
After completing arthroscopy of the intra-articular compartment with a standard supine technique, the traction is released, the hip is flexed 45 degrees, and standard portals are established in the peripheral compartment (TECH FIG 2).
The iliopsoas tendon can be exposed in line with the medial synovial fold, proximal to the zona orbicularis.
Occasionally, a communication is present at this location between the joint and the iliopsoas bursa.
If no communication is present, a capsular window can be created with a shaver.
The capsule in this location is thin, and often the tendon is visible or palpable through the thin capsule.
TECH FIG 1 • Release of right iliopsoas tendon from lesser trochanter. A. The hip is flexed approximately 20 degrees and externally rotated. B. Initial portal established at level of lesser trochanter. C.Ancillary portal is established distally under direct arthroscopic visualization. D. The arthroscope has been switched to the more distal portal with a flexible radiofrequency (RF) device introduced proximally. E. Arthroscopic illustration shows release of the tendinous portion of the iliopsoas. (Courtesy of J. W. Thomas Byrd, MD.)
TECH FIG 2 • Arthroscopic view from the peripheral compartment of a right hip. A. A window (arrows) has been created through the thin medial capsule, exposing the iliopsoas tendon (*) anterior to the femoral head (FH). B. The tendinous portion is released with a basket. C. The final fibers are débrided with a power shaver. D. Through the capsular window (arrows) the tendon has been completely released, preserving the muscular fibers (*). The relation between the capsular window and the acetabular labrum (AL) and femoral head (FH) is identified. (Courtesy of J. W. Thomas Byrd, MD.)
If the glistening tendon is not immediately visible, it should come into view after the capsular window is extended laterally.
At the level of the joint, the tendon fibers of the iliopsoas lie on the posterior surface of its muscular portion.
The muscular portion separates the tendon from the femoral nerve, which is the most lateral of the femoral neurovascular structures.
The tendon can be transected with a combination of hand biter instruments, power shaver, and thermal device.
TENDOPLASTY OF THE ILIOTIBIAL BAND
Open Technique
A straight, lateral longitudinal incision is centered over the greater trochanter (TECH FIG 3).
The length is dictated by the amount of exposure needed to precisely accomplish the tendoplasty.
A smaller incision is more cosmetic and can be accomplished with dissection of the subcutaneous tissues and selective retraction but should not compromise visualization for the procedure.
Several authors have described variations of a similar method for relaxing the tendon. These are based on an 8to 10-cm longitudinal incision just posterior to the mid part of the greater trochanter in the thickest portion of the iliotibial band.
Relaxation of the tendon is completed with paired or staggered 1to 1.5-cm transverse incisions.
The field is relatively bloodless, but meticulous hemostasis should be maintained and the subcutaneous tissues closed in layers to avoid formation of a hematoma.
Endoscopic Technique
Two portals are used: one 3 cm proximal to the tip of the greater trochanter and one 3 cm distal.
The arthroscope is placed from the distal portal site down to the subcutaneous surface of the iliotibial band.
Then, with arthroscopic visualization, the proximal portal is established for dissection to release the subcutaneous tissue from the superficial surface of the tendon (TECH FIG 4).
A 4- to 5-cm longitudinal incision within the tendon is created using a shaver and a radiofrequency (RF) probe.
An anteriorly based transverse incision is then made and the flaps resected, creating a long, obtuse triangle.
This provides better visualization to determine the relation of the iliotibial band and the underlying greater trochanter.
Portions of the trochanteric bursa can be resected as necessary for treatment and clearing the field of view.
Lastly, a posterior transverse incision is made and the flaps excised, creating a diamond-shaped pattern of resection.
Hemostasis should be meticulously maintained and a compressive dressing applied to minimize the formation of a hematoma.
TECH FIG 3 • Our preferred approach includes an 8to 10-cm longitudinal incision, posterior to the midpoint of the greater trochanter, with two pairs of 1to 1.5-cm transverse incisions. This relaxes the iliotibial band, eliminating the snapping, without creating any suture repair lines that would necessitate prolonged convalescence. A. Incision pattern. B. Relaxing response to incision. C. Appearance at surgery. (Courtesy of J. W. Thomas Byrd, MD.)
TECH FIG 4 • Endoscopic method of iliotibial band tendoplasty, shown in the right hip. A. After creating the longitudinal incision, the anterior limb is created by a perpendicular incision. B. Resecting the edges creates a triangle that aids in visualization of the underlying structures. C. The posterior limb is then created, and resection completes the diamond pattern of the tendoplasty. (Adapted from Ilizaliturri VM Jr, Martinez-Escalante FA, Chaidez PA, et al. Endoscopic iliotibial band release for external snapping hip syndrome. Arthroscopy 2006;22:505–510.)
POSTOPERATIVE CARE
After these procedures, the patient is capable of full weight bearing, but crutches are used for about 2 weeks until the gait pattern is normalized.
Gentle range-of-motion, closed-chain, and stabilization exercises are introduced as symptoms allow.
For iliopsoas release, aggressive hip flexion strengthening is avoided for the first 6 weeks; for the iliotibial band, aggressive stretching generally is not necessary.
The patient should not anticipate returning to vigorous activities for at least 3 months.
OUTCOMES
For endoscopic release of the iliopsoas tendon, several studies have reported highly predictable results in terms of eliminating the snapping and patient satisfaction.4,9
However, we have observed two cases of heterotopic ossification that occurred following release of the iliopsoas tendon from the lesser trochanter.
These observations are consistent with reports in the literature on open techniques of the iliopsoas tendon that have noted a propensity for heterotopic bone formation.13
For snapping of the iliotibial band, tendon-relaxing procedures that maintain the structural integrity of the abductor mechanism, whether performed open or endoscopically, have predictably corrected the snapping with minimal morbidity.3,8,15
COMPLICATIONS
No reports have been published of complications with endoscopic release of the iliopsoas tendon.
We have observed two cases of heterotopic ossification, for which the use of pharmacologic prophylaxis is recommended.13
Potential complication due to damage to surrounding structures (eg, femoral neurovascular bundle)
No complications have been reported in conjunction with the less extensive tendon-relaxing procedures for a snapping iliotibial band. Careful attention to the precision of the release can help avoid inadequate or excessive tendoplasty. Inadequate release could result in residual symptoms, whereas excessive release could result in a virtually unsalvageable compromise of the abductor mechanism.
REFERENCES
1. Allen WC, Cope R. Coxa saltans: the snapping hip revisited. J Am Acad Orthop Surg 1995;3:303–308.
2. Brignall CG, Stainsby GD. The snapping hip, treatment by Z-plasty. J Bone Joint Surg Br 1991;73B:253–254.
3. Byrd JWT. Snapping hip. Oper Tech Sports Med 2005:13:46–54.
4. Byrd JWT. Evaluation and management of the snapping iliopsoas tendon. Instr Course Lect 2006;55:347–355.
5. Dobbs MB, Gordon JE, Luhmann SJ, et al. Surgical correction of the snapping iliopsoas tendon in adolescents. J Bone Joint Surg Am 2002;84A:420–424.
6. Gruen GS, Scioscia TN, Lowenstein JE. The surgical treatment of internal snapping hip. Am J Sports Med 2002;30:607–613.
7. Henry AK. Extensile Exposure, ed 2. New York: Churchill Livingstone, 1973.
8. Ilizaliturri VM Jr, Martinez-Escalante FA, Chaidez PA, et al. Endoscopic iliotibial band release for external snapping hip syndrome. Arthroscopy 2006;22:505–510.
9. Ilizaliturri VM Jr, Villalobos FE Jr, Chaidez PA, et al. Internal snapping hip syndrome: treatment by endoscopic release of the iliopsoas tendon. Arthroscopy 2005;21:1375–1380.
10. Kim DH, Baechler MF, Berkowitz MJ, et al. Coxa saltans externa treated with Z-plasty of the iliotibial tract in a military population. Military Medicine 2002;167:172–173.
11. Provencher MT, Hofmeister EP, Muldoon MP. The surgical treatment of external coxa saltans (the snapping hip) by Z-plasty of the iliotibial band. Am J Sports Med 2004;32:470–476.
12. Taylor GR, Clarke NMP. Surgical release of the “snapping iliopsoas tendon.” J Bone Joint Surg Br 1995;77B:881–883.
13. Velasco AD, Allan DB, Wroblewski BM. Psoas tenotomy and heterotopic ossification after Charnley low-friction arthroplasty. Clin Orthop Relat Res 1993;291:93–95.
14. Wettstein M, Jung J, Dienst M. Arthroscopic psoas tenotomy. Arthroscopy 2006;22:907.e1–4.
15. White RA, Hughes MS, Burd T, et al. A new operative approach in the correction of external coxa saltans: the snapping hip. Am J Sports Med 2004:32:1504–1508.