Victor M. Ilizaliturri Jr. was born in Mexico City on 27th December 1967. He is a Specialist in Orthopaedic Surgery, and a subspecialist in Hip Reconstructive and Hip Preserving Surgery. He is currently the Chief of the service of Adult Joint Reconstruction at the National Rehabilitation Institute of Mexico and Professor of Adult Joint Reconstruction Hip and Knee from the Universidad Nacional Autónoma de México (UNAM). He is a well-known figure in hip arthroscopic surgery, lecturing, travelling and teaching widely. In addition he has contributed extensively to the design and development of special instruments for arthroscopic surgery of the hip joint. He is currently a consultant for Smith and Nephew Endoscopy in the field of hip arthroscopy and is a Founding Member of the International Society for Hip Arthroscopy.
The internal snapping hip syndrome is produced by the iliopsoas tendon snapping over the iliopectineal eminence or the femoral head. The iliopsoas tendon is located lateral to the iliopectineal eminence when the hip is in full flexion, with hip extension the tendon is displaced medially until it positions medial to the iliopectineal eminence when the hip is in neutral position. The snapping phenomenon can occur without pain in up to 10% of the general population and should be considered a normal occurrence. The symptomatic internal snapping hip syndrome always presents pain in the groin associated with the snapping phenomenon. The snapping phenomenon is reproduced when bringing the hip to extension from a flexed position. The patients report snapping while stair climbing or standing from a chair. The snapping phenomenon is always voluntary and reproducible, this is important to do a differential diagnosis with intra-articular pathology.
Examination and imaging
Physical examination of the internal snapping phenomenon is done with the patient supine by flexing the affected hip more than 90° and extending to neutral position. This maneuver will reproduce the snapping phenomenon at the front of the groin, which will be mentioned to the examiner by the patient when it occurs. The snapping phenomenon cannot be observed through the skin, but frequently produces an audible snap. This may be accentuated with abduction and external rotation in flexion, and adducting and internally rotating while extending. The snapping phenomenon may be palpated by placing the hand over the affected groin. When the snapping is symptomatic, there is always an apprehension response from the patient when it occurs. Other positive findings in physical examination such as the presence of a c-sign, a positive log roll test or a positive impingement test may be related to the presence of intra-articular hip pathology. More than half of the patients with internal snapping hip syndrome have associated intra-articular hip pathology.
Plain radiographs are usually normal; in some cases a cam femoroacetabular impingement deformity may be documented. Psoas bursography may outline the tendon and, if combined with fluoroscopy, may document the snapping phenomenon dynamically. The main problem is that it depends on the ability of the technician to reproduce the snapping while examining hip motion within the range of view of the C-arm. Ultrasonography of the iliopsoas tendon is a dynamic non invasive study that may document the snapping phenomenon as well as pathologic changes of the iliopsoas tendon and its bursa. Psoas ultrasonography also depends on the ability and experience of the examiner. More recently, ultrasonography has also been used to describe new mechanisms of iliopsoas snapping, like the bifid iliopsoas tendon or snapping of the iliopsoas over the iliacus muscle and snapping of the iliopsoas tendon over paralabral cysts. Because almost half of the patients with internal snapping hip syndrome have associated intra-articular hip parthology, magnetic resonance arthrography (MRA) is the diagnostic study we prefer. It may demonstrate intra-articular pathology and report changes related to the iliopsoas tendon and bursa. The snapping phenomenon cannot be documented using MRA.
Impingement
Iliopsoas impingement may be present in both natural and artificial hips.
In the case of a natural hip, it has been theorized that because of its close relationship to the anterior hip, a tight iliopsoas tendon may be a cause of anterior labral lesions. The clinical presentation of this form of iliopsoas impingement may not be accompanied by a snapping phenomenon and have positive impingement tests, log roll and mechanical hip symptoms more in accordance with symptoms related to a labral tear.
When iliopsoas impingement occurs in presence of total hip replacement (THR), affected patients typically report persisting groin pain that is exacerbated by stair climbing, getting into or out of bed or a chair and entering and exiting an automobile. A snapping phenomenon or a clunk is usually not present. Gait may be affected with the patient presenting a slight limp. It is important to remember that the patients must first be evaluated for more common causes of groin pain after THR like infection, component loosening and occult periprosthetic fractures. A typical finding at radiographs or CT is a protruding anterior implant rim uncovered by the bony anterior acetabular wall.
Conservative treatment for both conditions (iliopsoas impingement in natural and artificial hip joints) is the same including rest, NSAIDs and physical therapy. Iliopsoas injections are of limited therapeutic value, but they represent a very reliable diagnostic test. After failure of conservative treatment, surgical release of the iliopsoas tendon may be indicated.
| Images: Ilizaliturri VM |
In the case of iliopsoas impingement with a natural hip joint, hip arthroscopy will provide access for treatment of the associated lesions such as labral tears or underlying bony impingement.
When iliopsoas impingement is present in an artificial total hip joint, acetabular component revision for re-orientation and open iliopsoas release have been reported. Both techniques seem to be effective in the treatment of iliopsoas impingement with the open release of the iliopsoas tendon presenting less morbidity. It is also possible to perform endoscopic release of the iliopsoas tendon in a THR, but reported results in the peer-reviewed literature is limited.
Endoscopic release
Endoscopic release of the iliopsoas tendon has evolved over the past decade. A variety of surgical techniques is available for release of the iliopsoas tendon at different anatomical regions.
As described from proximal to distal, endoscopic release of the iliopsoas tendon may be transcapsular at two different sites: from the central compartment and from the hip periphery. It can also be performed within the iliopsoas bursa at its insertion on the lesser trochanter. For either one of these techniques, the patient is positioned for hip arthroscopy in supine or lateral decubitus (Figure 1).
Iliopsoas tendon from the central compartment is performed with the hip joint in traction. The anterolateral portal, as described by Byrd at the anterior superior corner of the greater trochanter, is used as the viewing portal. With a 70° arthroscope, the anterior capsule is identified. From the direct anterior portal, a radiofrequency hook probe or an arthroscopic banana knife is introduced to create an anterior hip capsulotomy relative to the 2 and 3 o’clock position of the labrum in a right hip or geographic zone 1. Fibers of the iliopsoas tendon are visualized through the capsulotomy. The tendon is further exposed using a mechanical shaver. A radiofrequency hook probe is used to release the tendon in a retrograde fashion leaving the iliacus muscle intact (Figure 2).
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Iliopsoas tendon release from the hip periphery is performed without traction. A 70° or a 30° arthroscope is positioned into the peripheral compartment anterior and inferior to the femoral neck through the anterolateral portal. Landmarks at the hip periphery must be identified. The medial synovial fold serves as the best landmark to identify the inferior aspect of the head and neck (6 o’clock position). The proximal origin of the medial synovial fold at the inferior head-neck junction is visualized. The field of view is rotated to the anterior hip capsule. The mid anterior portal is used to introduce instruments into the peripheral compartment. Between the anterior inferior labrum and the anterior inferior zona orbicularis a capsulotomy is performed and the iliopsoas tendon fibers identified through the capsulotomy, in some cases a natural communication between the anterior hip capsule and the iliopsoas bursa is present at this level. The tendon is further exposed using a mechanical shaver. Finally, the iliopsoas tendon is released in a retrograde fashion using a radiofrequency hook probe. The iliacus muscle is left intact behind the released iliopsoas tendon (Figure 3).
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The iliopsoas bursa
Using an accessory portal, a spinal needle is introduced into the iliopsoas immediately proximal to the lesser trochanter. The anterior aspect of the proximal femur may be palpated to navigate the needle in the sagital plane and an image intensifier is used to navigate the needle in the coronal plane. With the needle in position directly proximal to the lesser trochanter, the stylus is removed and a guidewire introduced, the cannulated hip arthroscopy instruments are used to establish a viewing portal. A 30° arthroscope is introduced and the fibers of the iliopsoas tendon at its insertion on the lesser trochanter is identified. A second accessory portal is established triangulating a spinal needle to the tip of the arthroscope. Once the needle is observed inside the iliopsoas bursa, a guide wire and cannulated hip arthroscopy instruments are used to establish a working portal. The iliopsoas tendon is further exposed using a mechanical shaver and released in a retrograde fashion using a radiofrequency hook probe (Figure 4).
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Surgical anatomy of the iliopsoas tendon is important when doing an endoscopic release. The level of the release will determine the volume of the tendon that is cut and the resulting volume of the muscle fibers that are kept un-released. In a cross sectional anatomic study of the iliopsoas tendon, Zellner et al reported the average diameter and percentage of tendon and muscle at different levels. Using 20 embalmed cadavers they measured the diameter of the muscle-tendon unit of the iliopsoas at the level of the labrum, the hip periphery and its insertion on the lesser trochanter. At each one of the described levels, they looked at the percentage of tendon and muscle. They reported that the average circumference of the iliopsoas muscle tendon unit at the level of the labrum was 68.3 mm in diameter, at the level of the hip periphery 58 mm in diameter and at the lesser trochanter 45.7 mm in diameter. At the level of the labrum, the muscle tendon unit consisted of 40% tendon and 60% muscle; at the level of the hip periphery, it consisted of 53% tendon and 47% muscle; and at the level of the lesser trochanter insertion, it consisted of 60% tendon and 40% muscle. Based on this information, a more proximal release will leave more muscle tissue left intact and affect less the overall volume of the muscle tendon unit. This, in theory, may produce less functional compromise but could also be related to more frequency of recurrence of the snapping phenomenon after release.
Our current protocol for release of the iliopsoas tendon in a primary case is at the level of the labrum. In the case of iliopsoas tendinitis in the presence of THR, our preferred technique is to release the tendon at its insertion on the lesser trochanter due to the large amount of scar tissue that may be present at the front of the prosthetic joint.
Results
Encouraging results have been reported with endoscopic release of the iliopsoas tendon in the treatment of the internal snapping hip syndrome. The most common technique reported has been release at the lesser trochanter. Endoscopic release at the lesser trochanter has also been successful in the treatment of athletic population with internal snapping hip syndrome. In general, there are higher success rates and less recurrence when the endoscopic technique is compared with the open procedures. This may be because in the endoscopic studies that are published, arthroscopic treatment of intra-articular associated pathology has been performed. Frequent procedures reported in the literature to treat associated injuries are remodeling of femoroacetabular impingement deformities, labral repair or partial labral resection and cartilage lesions repair (removal of unstable cartilage and microfractures).
There is less literature regarding the success of endoscopic transcapsular release of the iliopsoas tendon at the level of the labrum or at the hip periphery. The author has reported a comparative prospective randomized study of the technique for release of the iliopsoas tendon at the lesser trochanter and transcapsular at the hip periphery, and found no difference statistically significant difference between both techniques.
Heterotopic bone formation has been reported associated with release of the iliopsoas tendon. This complication may be associated with the need for further surgical procedures and compromise treatment outcome. This has been reported for both open and endoscopic release at the level of the lesser trochanter. Prophylaxis with 400 mg per day of celecoxib seems to be effective in preventing this complication, but more evidence is needed. In the case of internal snapping hip, recurrence may be secondary to incomplete release or inadequate management of associated bony deformities. More recently, the presence of a bifid iliopsoas tendon has been reported as a cause of recurrence of snapping after endoscopic iliopsoas tendon release. To avoid this complication, the presence of the bifid tendon should be identified before surgery with adequate imaging. It is better visualized with a long medial capsulotomy from the hip periphery.
