Coxa Saltans: The Snapping Revisited

William C. Allen, MD, and Ray Cope, MD

Abstract that it comes to lie anterior to the Coxa saltans, or “snapping hip,” has several causes. These can be divided into three greater trochanter. types: external, internal, and intra-articular. Snapping of the external type occurs The has two major when a thickened area of the posterior iliotibial band or the leading anterior edge of musculotendinous attachments the snaps forward over the greater trochanter with flexion of the proximally, the tensor lata hip. The internal type has a similar mechanism except that it is the musculotendi- anteriorly and the gluteus maximus nous that snaps over structures deep to it (usually the femoral head and posteriorly. There is also an indirect the anterior capsule of the hip). Intra-articular snapping is due to lesions in the attachment to the joint itself. Diagnosis of the external and internal types is usually made clinically. through its overlying aponeurosis.7 Radiography can be useful in confirming the diagnosis, particularly when bursog- These muscles pull on the iliotibial raphy shows the iliopsoas tendon snapping with hip motion. Other radiologic tract, making it taut whether the hip modalities, such as computed tomography, magnetic resonance imaging, and is flexed or extended. The iliotibial arthrography, may also be helpful, especially when there is an intra-articular cause. tract is firmly attached on its deep Most cases of snapping hip are asymptomatic and can be treated conservatively. surface to the linea aspera and the However, if the snapping becomes symptomatic, surgery may be necessary. There posterior femur. Through this may also be a role for arthroscopy in the treatment of intra-articular lesions. broad-based attachment, the three J Am Acad Orthop Surg 1995;3:303-308 muscles gain an indirect insertion into the femur. Distally, the thick- ened posterior border of the iliotibial Coxa saltans, or “snapping hip,” is musculotendinous iliopsoas as it tract crosses the anterolateral aspect characterized by an audible snap- snaps over the structures located of the and inserts on the lateral ping, usually with flexion and behind it, the most common site at Gerdy’s tubercle. The ante- extension of the hip during exercise being the femoral head.1,2 Intra-artic- rior portion of the tract flares out into or simply with normal activities of ular lesions may be due to a variety the lateral retinaculum, with some daily living. It is often accompanied of causes, such as synovial chondro- fibers attaching to the lateral patella. by . Most cases involve slip- matosis, loose bodies, fracture frag- Because the iliotibial tract ping of the gluteus maximus or the ments, and labral tears, which may remains taut throughout motion of iliotibial tract over the greater present a diagnostic problem for the the hip, not only does it act as a ten- trochanter. However, there are clinician. sion band on the lateral , but other causes, and confusion can arise when symptoms are due to one External Type of these. The external type of snapping is Dr. Allen is Professor of Orthopaedic Surgery, commonly caused by the iliotibial School of Medicine, University of Missouri, tract sliding over the greater Columbia. Dr. Cope is Professor of Radiology and Orthopaedic Surgery, School of Medicine, Causes trochanter. A thickening of the pos- University of Missouri, Columbia. terior part of the iliotibial tract or the The causes of coxa saltans can be anterior border of the gluteus max- Reprint requests: Dr. Allen, University of Mis- classified as external, internal, and imus enhances the snapping.1,3-6 The souri Hospital, One Hospital Drive, M562, intra-articular. The external type of thickened band lies posterior to the Columbia, MO 65212. snapping involves the greater trochanter when the hip is in exten- trochanter and its overlying soft tis- sion and snaps forward over the Copyright 1995 by the American Academy of Orthopaedic Surgeons. sues. The internal type involves the greater trochanter with flexion, so

Vol 3, No 5, September/October 1995 303 Coxa Saltans any small anatomic change or iliopectineal eminence and the ante- Other areas behind the iliopsoas swelling may precipitate snapping rior inferior iliac spine.4 The musculo- that are known to cause snapping over the greater trochanter. The tendinous junction consistently occurs are a prominence of the iliopectineal greater trochanteric bursa lies at the level of this osseous groove, ridge and exostoses of the lesser between the iliotibial tract and the with the bulk of the tendon being infer- trochanter. In some patients, a dis- greater trochanter, and it may ior to the bony . From its most crete tendinous slip arises from a become inflamed and cause pain lateral location, when the hip is in full position superior to the bony pelvis,4 when snapping occurs. flexion, abduction, and external rota- and this slip may snap on the tion, to its most medial position, when iliopectineal ridge. Internal Type the hip is in extension, adduction, and Another cause of internal snap- The internal type of coxa saltans internal rotation, the major conjoined ping is attributable to the iliopsoas was first reported from Argentina in iliopsoas tendon remains in this bursa. The bursa has well-defined a brief report of three cases.6 It was groove.1,4 However, it moves from the anatomic boundaries, with the mus- postulated that the psoas tendon lateral to the medial side of the culotendinous part of the iliopsoas was slipping over the iliopectineal femoral head when the hip moves muscle lying anterior and the cap- eminence. Following iliopsoas from flexion to extension, and it sule of the hip joint and the lengthening, good results were moves from the medial to the lateral iliopectineal eminence being poste- obtained in two of the three patients. side of the femoral head when the hip rior. The bursa extends medially to Studies reported from the Univer- moves from extension to flexion (Fig. the iliopectineal line and laterally to sity of Missouri pertaining to the inter- 1). In the majority of symptomatic the anterior inferior iliac spine. nal type of snapping have shown that cases of internal-type coxa saltans, it is Proximally, it may extend up into the iliacus and psoas muscles con- this motion back and forth over the the iliac fossa; distally, to the lesser verge and fuse together as they pass femoral head that causes the snap- trochanter. It is the largest synovial through a groove between the ping. bursa in the body and can measure up to 7 cm in length and 4 cm in width.8 The bursa and the hip joint communicate in approximately 15% of ; this communication may be secondary to attritional changes.4

Intra-articular Type If the snapping is caused by an intra-articular lesion, such as a loose body, it may occur intermittently if the loose body can lodge in the foveal area of the acetabulum or in a redun- dant synovial fold. Most of the intra- articular causes of snapping have a distinctive presentation and should not be confused with snapping of the external or internal type. Tears of the are included as a possible cause of snap- ping, but such tears far more often cause pain.9-11 They are usually located in the posterosuperior por- tion of the labrum, which seems to ABbe the most vulnerable to mechani- cal stress.9 There is also an increased incidence of labral tears in dysplastic Fig. 1 A, With flexion of the hip, the iliopsoas tendon shifts laterally in relation to the cen- ter of the femoral head. B, With extension of the hip, the iliopsoas tendon shifts medially in hips, which may be due to the con- relation to the center of the femoral head. stant increased pressure on the rim of the acetabulum.10 In severe

304 Journal of the American Academy of Orthopaedic Surgeons William C. Allen, MD, and Ray Cope, MD trauma cases, such as a dislocation When the external type of coxa for anterolateral knee instability, with a large tear of the labrum, saltans is suspected, the patient is with the mechanism being related to actual locking may occur. placed on his or her side with the alterations in the mechanics of the affected leg up. The hip is then iliotibial tract in susceptible individ- flexed actively by the patient as the uals.17 History and Physical examiner palpates the area of the Other unusual causes of snapping Examination greater trochanter so that the snap- include capsular and synovial folds, ping can be felt. As in the internal synovial chondromatosis, loose In cases of coxa saltans of the inter- type of coxa saltans, the diagnosis is intra-articular bodies, exostoses,12 nal and external types, the history is corroborated if the snapping can be and stenosing of the usually fairly diagnostic in itself. blocked by applying pressure at the iliopsoas tendon and sheath near its The patient will describe a snapping, level of the greater trochanter. femoral insertion.18,19 In children painful sensation and will usually Both the internal and external and teenagers, habitual hip disloca- point to the area of the greater types of snapping can sometimes be tion may occasionally present as a trochanter or the front of the hip. In best reproduced by the patient when snapping hip.20,21 Slipping of the addition, the patient will frequently he or she is standing. This is particu- iliofemoral ligaments over the volunteer to demonstrate the snap- larly true of the external type. When femoral head19 and slipping of the ping. Questions regarding specific this is the case, palpating the area of long head of the biceps femoris ten- activities that produce the snapping snapping and applying pressure just don over the ischial tuberosity22 will also generally guide the physi- as one would do with the patient on have also been proposed as causes of cian to the proper diagnosis. his or her side should be done for snapping, but no pathologic or sur- Patients with intra-articular corroboration of the diagnosis. gical basis has yet been identified.4 lesions usually complain of a clicking As noted previously, the most sensation rather than a snapping. common form of coxa saltans Pain is generally their primary com- involves slipping of either the ante- Radiologic Evaluation plaint. Tears of the labrum or small rior border of the gluteus maximus fracture fragments secondary to or the thickened posterior border of There appears to be uncertainty trauma are common causes. In such the iliotibial tract over the greater among radiologists about how coxa cases, the history will disclose that trochanter.1,4,12 Patients are charac- saltans is best investigated. Only a the pain was acute in onset and was teristically in their late teens or twen- single case report is available in the associated with significant trauma. ties at presentation; athletes and radiologic literature.23 Researchers A history of trauma may also be a dancers13 are frequently involved.14 at the University of Missouri have causative factor in the external and Most of the patients have pain, and if not found plain radiographs to be internal types of coxa saltans, but this pain is present, it is invariably sec- useful in diagnosis, except to is much less frequently the case. The ondary to trochanteric .12 exclude conditions such as synovial trauma described is usually minor This form of coxa saltans is consid- chondromatosis and loose bodies. and may have occurred several years ered to be external. A variety of plain-film measure- before the patient’s presentation. Other external causes of snapping ments have been described.16,24,25 It On physical examination when have recently been reported. After has been claimed that a smaller- the internal type of coxa saltans is total hip replacement, especially than-normal bi-iliac width is associ- suspected, the examiner can fre- when a curved femoral stem has ated with an increased degree of quently reproduce the snapping been used, snapping at the hip can valgus angulation at the hip, which by having the patient lie in a occur if the placement of the femoral can lead to imbalance between hip supine position and then flex and component is too far medial, with abductors and adductors.24,25 How- extend the hip. Sometimes it helps angulation of the stem in relation to ever, other studies have not con- to flex and then abduct the hip, fol- the long axis of the femur.15 A firmed this hypothesis and have lowed by extension and adduc- reduced femoral neck angle may found coxa vara to be more common tion. If the snapping occurs with also contribute to snapping. In both in patients with snapping.16 these motions, blocking the snap- circumstances, slipping of the poste- Magnetic resonance imaging has ping by applying finger pressure rior iliotibial tract over the greater not been used often. However, it over the iliopsoas tendon at the trochanter is thought to be responsi- may be of help in patients who have level of the femoral head will cor- ble for the snapping.15,16 Snapping intra-articular lesions, particularly roborate the diagnosis. has also been described after surgery labral tears.

Vol 3, No 5, September/October 1995 305 Coxa Saltans

A diagnostic role has also been proposed for computed tomogra- phy, and comparisons of the two iliopectineal eminences have been said to provide the most valuable evidence in the internal type of snap- ping.14 However, the iliopectineal eminence is involved in only a small percentage of such cases, and this study will therefore be of interest in only the occasional case. Computed tomography can be useful, however, in demonstrating the anatomy of the iliopsoas tendon. There are a few anecdotal reports of ultrasonography being diagnostic AB in cases of internal snapping. Cer- tainly, it would appear theoretically Fig. 2 Iliopsoas bursography. A, A hip arthrogram was initially obtained. The spinal nee- dle was then retracted approximately 5 mm, and the iliopsoas bursa (asterisk) was depicted. possible to demonstrate a tendinous The iliopsoas tendon (arrow) was seen as a filling defect. B, Injection of more contrast mate- snap with real-time ultrasound. rial demonstrated the full extent of the iliopsoas bursa (asterisk). The iliopsoas tendon However, allegedly successful (arrow) was again visualized as a filling defect. results have not generally been reproducible, and there are, as yet, no reported cases of success with the iliopsoas tendon sheath. The hip ent, and is of the external or internal ultrasonography in this area. should then be exercised or manipu- variety, the best conservative treat- Iliopsoas bursography is the lated through a full range of move- ment is rest and avoidance of those definitive and single most useful ment; even better is for the patient to activities that produce the snapping. procedure. It is easily performed1,8 voluntarily snap the hip. A sudden If the snapping has become present and, although invasive, is virtually jerking of the iliopsoas tendon, with with routine activities and is painful, free of complications in experienced a lateral to medial movement, is nonoperative treatment includes hands. diagnostic of this form of internal rest and the injection of hydrocorti- The technique of iliopsoas bur- snapping; this movement can be sone, followed by a careful exercise sography has been fully described.4,8 noted on the video monitor. program that includes stretching of After the usual patient preparation the involved muscles without hav- and draping, an 18-gauge spinal ing them snap. The vast majority of needle is placed under fluoroscopic Treatment patients with a symptomatic snap- control over the superomedial quad- ping hip improve with conservative rant of the femoral head. With the therapy.1,12 Under a controlled pro- patient under local anesthesia, the Conservative Therapy gram, it may be possible for the needle is advanced until bone con- One should think of the snapping patient to regain normal use of the tact is made and then is retracted 5 of the internal and external types as hip over a period of 6 to 12 months. mm. Contrast material is then a normal occurrence. Many people Even after this, the patient must be injected, defining a closed space experience benign, asymptomatic careful to avoid repetitive snapping extending from above the acetabu- snapping on an infrequent basis, and by modification of his or her exercise lum and across the medial aspect of no treatment is needed. program or sport. the femoral head toward the lesser It is the rare individual who expe- trochanter. riences symptomatic snapping. It The iliopsoas tendon is usually usually develops over a long period Surgical Treatment imaged as a filling defect seen adja- of time and finally becomes painful cent to the opacified iliopsoas bursa enough for the patient to seek med- External Type (Fig. 2). If desired, the needle can be ical help. If the snapping is of recent For the exceedingly rare patient retracted further, and contrast onset (within the previous 6 with external-type snapping who medium can be injected directly into months), is only intermittently pres- does not improve with conservative

306 Journal of the American Academy of Orthopaedic Surgeons William C. Allen, MD, and Ray Cope, MD therapy, surgery is required. In begins to arborize at this level and used, and a compressive dressing is most cases, excision of the greater varies from person to person, there applied. The procedure is usually trochanteric bursa with Z-plasty of may be many smaller branches, done with the patient under general the iliotibial band should be per- which should be preserved. Because anesthesia in an outpatient surgery formed. This procedure is explained the femoral neurovascular bundle unit, and the patient is discharged in detail in the literature.12,26 This lies on the anteromedial side of the the day of surgery. form of surgery is also indicated iliopsoas muscle, the tendinous por- when snapping develops after total tion, which is located under the mus- Intra-articular Type hip replacement or an operation cle, should be approached from the For patients with intra-articular designed to correct knee insta- lateral side of the muscle belly with lesions, arthroscopy is being done to bility.15-17 the use of blunt dissection medial to remove loose bodies or to resect the sartorius and then between the tears of the labrum.9,10 We have not Internal Type rectus femoris (straight head) and had experience with hip arthroscopy Painful internal-type snapping the muscle belly of the iliacus. The because so few patients need this that is refractory to conservative, conjoint tendon of the iliopsoas is procedure. Large loose bodies or nonoperative treatment is also exposed by turning the iliacus medi- synovial chondromatosis may war- extremely rare. Lengthening of the ally. As the tendon is followed dis- rant an open approach to the hip to posterolateral tendinous portion of tally, the surgeon can feel the remove the mechanical impediment the iliopsoas tendon will give good insertion of the tendon on the lesser they produce. results in most cases. Postopera- tuberosity. If spurs or exostoses on tively, many patients will continue the lesser tuberosity that could be to have some snapping, but almost causing the snapping are detected, Summary always the pain has been eliminated they should be removed with an and they are satisfied with the result. osteotome or a rongeur. The causes of coxa saltans can be This procedure will be described in The tendon is then partially classified as external, internal, and more detail, as it is not often found released about 2 cm proximal to the intra-articular. In the external vari- in the literature. lesser tuberosity. In this distal te- ety, a thickened area of the posterior The surgery is done via a cosmetic notomy, approximately 50% of the iliotibial band or the leading anterior groin incision extending from tendon is cut through. Three or four edge of the gluteus maximus snaps approximately l cm medial to the transverse incisions, approximately forward over the greater trochanter femoral pulse laterally along the 2 cm apart, are then made in the ten- with flexion of the hip. The mecha- inguinal crease for 8 to 10 cm. The don. The most proximal tenotomy is nism of the internal variety is similar incision crosses the femoral neu- at the level of the superior portion of except that it is the musculotendi- rovascular bundle medially and the the femoral head, which is easily felt nous iliopsoas that snaps over the lateral femoral cutaneous nerve at in the base of the wound through its structures deep to it (in most cases, the lateral end of the incision. The capsule. When the musculotendi- the femoral head and the anterior femoral artery and nerve are easily nous portion of the muscle is capsule of the hip). Intra-articular located because of the pulse. The lat- reached, as one moves proximally, conditions that can cause mechani- eral femoral cutaneous nerve, how- the tendinous portion is entirely cal snaps in the joint include syno- ever, varies in its anatomic position released so that continuity of the vial chondromatosis, loose bodies, somewhat as it crosses the sartorius iliopsoas is through the muscle fracture fragments, and labral tears. muscle from medial to lateral fibers and the investing structures The diagnosis can usually be made approximately 2.5 cm distal to the anteriorly. The tendinous portion of clinically if coxa saltans is of the exter- anterior superior iliac spine. Careful the muscle-tendon unit lies posteri- nal or internal type. Radiography, dissection will allow identification orly. The femoral nerve and vessels particularly iliopsoas bursography, of this nerve. lie anterior to the muscle and are can be useful in confirming the Starting at the medial border of thus protected as long as just the diagnosis. Computed tomography, the sartorius, after the nerve is tendinous portion is released. magnetic resonance imaging, and found, the deep fascia is opened, After the tenotomies, small blood arthrography may also be helpful, paralleling the skin incision and vessels are coagulated as needed, and particularly when there is an intra- extending medially to the femoral the deep fascia is closed with inter- articular cause. nerve. Care must be taken as one rupted sutures. A subcuticular clo- The vast majority of patients with approaches the nerve; because it sure is performed. No drains are snapping hip can be treated conser-

Vol 3, No 5, September/October 1995 307 Coxa Saltans vatively. However, surgery may be copy may prove useful in the treat- Acknowledgment: The authors are grate- indicated if the condition becomes ment of intra-articular lesions that ful to Frances Cope for audiovisual ser- vices. chronically symptomatic. Arthros- are causing discomfort.

References 1. Jacobson T, Allen WC: Surgical correc- 10. Suzuki S, Awaya G, Okada Y, et al: Diagnostic criteria and clinical signifi- tion of the snapping iliopsoas tendon. Arthroscopic diagnosis of ruptured cance. Arch Phys Med Rehabil 1958;39: Am J Sports Med 1990;18:470-474. acetabular labrum. Acta Orthop Scand 617-622. 2. Lyons JC, Peterson LFA: The snapping 1986;57:513-515 19. Micheli LJ: Overuse injuries in chil- iliopsoas tendon. Mayo Clin Proc 11. Altenberg AR: Acetabular labrum tears: dren’s sports: The growth factor. Orthop 1984;59:327-329. A cause of hip pain and degenerative Clin North Am 1983;14:337-360. 3. Binnie JF: Snapping hip. Ann Surg . South Med J 1977;70:174-175. 20. Stuart PR, Epstein HP: Habitual hip 1913;58:59-66. 12. Zoltan DJ, Clancy WG Jr, Keene JS: A dislocation. J Pediatr Orthop 1991;11: 4. Schaberg JE, Harper MC, Allen WC: new operative approach to snapping 541-542. The . Am J hip and refractory trochanteric bursitis 21. Walker J, Rang M: Habitual hip disloca- Sports Med 1984;12:361-365. in athletes. Am J Sports Med 1986; tion in a child: Another cause of the 5. Mayer L: Snapping hip. Surg Gynecol 14:201-204. snapping hip. Clin Pediatr 1992;31: Obstet 1919;29:425-428. 13. Howse AJG: Orthopedists and ballet. 562-563. 6. Nunziata A, Blumenfeld I: Cadera a Clin Orthop 1972;89:52-63. 22. Rask MR: “Snapping bottom”: Sublux- resorte: A proposito de una variedad. 14. Rotini R, Spinozzi C, Ferrari A: Snap- ation of the tendon of the long head of Prensa Med Argent 1951;38:1997-2001. ping hip: A rare form with internal eti- the . Muscle Nerve 7. Johnson EW: Buttock, hip joint, and ology. Ital J Orthop Traumatol 1991; 1980;3:250-251. thigh, in Hollinshead WH (ed): Anato- 17:283-288. 23. Staple TW, Jung D, Mork A: Snapping my for Surgeons: The Back and Limbs, 2nd 15. Larsen E, Gebuhr P: Snapping hip after tendon syndrome: Hip tenography with ed. New York: Harper & Row, 1969, total hip replacement: A report of four fluoroscopic monitoring. Radiology vol 3, p 695. cases. J Bone Joint Surg Am 1988;70:919- 1988;166:873-874. 8. Harper MC, Schaberg JE, Allen WC: 920. 24. Jacobs M, Young R: Snapping hip phe- Primary iliopsoas bursography in the 16. Larsen E, Johansen J: Snapping hip. nomenon among dancers. Am Correct diagnosis of disorders of the hip. Clin Acta Orthop Scand 1986;57:168-170. Ther J 1978;32:92-98. Orthop 1987;221:238-241. 17. Satku K, Chia J, Kumar VP: Snapping 25. Singleton MC, LeVeau BF: The hip joint: 9. Ikeda T, Awaya G, Suzuki S, et al: Torn hip: An unusual cause. J Bone Joint Surg Structure, stability and stress—A acetabular labrum in young patients: Br 1990;72:150-151. review. Phys Ther 1975;55:957-973. Arthroscopic diagnosis and manage- 18. Anderson TP: Trochanteric bursitis: 26. Brignall CG, Stainsby GD: The snap- ment. J Bone Joint Surg Br 1988;70:13-16. ping hip: Treatment by Z-plasty. J Bone Joint Surg Br 1991;73:253-254.

308 Journal of the American Academy of Orthopaedic Surgeons