Commentary & Perspective on
"Surgical Correction of the Snapping Iliopsoas Tendon in Adolescents"
By Matthew B. Dobbs, MD et al.

Commentary & Perspective by
James H. Beaty, MD*,
Department of Orthopaedic Surgery, University of Tennessee-Campbell Clinic, Memphis, TN

Symptomatic "snapping hip" or coxa saltans is an uncommon condition that can be difficult to diagnose because of its rarity and because the symptoms can be caused by several different mechanisms. Generally, this condition is classified as one of three types: external, internal, and intra-articular^1-3. The external type, the most common, is usually caused by the sliding of the iliotibial tract over the greater trochanter³. The internal type most often involves snapping of the iliopsoas tendon over the iliopectineal eminence or the femoral head. Intra-articular snapping can be caused by a loose body in the joint, such as a fracture fragment or a torn labrum.

The difficulty of diagnosis is illustrated by the incorrect diagnoses initially made for all of the patients reported in this study (Table I), diagnoses that range from a "sprained hip" to aseptic necrosis to a herniated disk. The snapping about the hip was recognized in three patients but was attributed to the iliotibial band rather than to the iliopsoas tendon.

As Dobbs et al. pointed out, the most important tools in the diagnosis of snapping hip are the history and the physical examination. The first step toward a correct diagnosis is an awareness of the condition; there should be a high index of suspicion for this entity when an athlete engaged in running sports presents with salient symptoms. The position of the hip in which the snapping occurs, the location of the pain, and the specific activities that produce the snapping usually provide clear indications of the correct diagnosis. The reproducible painful snap of the iliopsoas that can be palpated anteriorly and medially over the affected hip is pathognomonic for the internal type of snapping hip.

Radiographs and magnetic resonance imaging scans can be used to rule out intra-articular causes of snapping but are not helpful in determining whether the iliopsoas tendon is involved in the etiology. Bursography, tenography, and ultrasound have been recommended to evaluate snapping of the iliopsoas tendon¹, but each modality has its limitations and, as the authors pointed out, imaging studies are generally unnecessary for the diagnosis.

The classic surgical treatment of the painful internal type of snapping hip has been lengthening of the iliopsoas tendon, which involves cutting through 50% of the tendon distally near its insertion on the lesser trochanter^1,2. Three to four additional cuts are made in the tendon slightly more proximally, and, when the musculotendinous portion of the muscle is reached, the tendinous portion is released entirely. Reported complications of this procedure have been hip flexion weakness and recurrent snapping. The technique described by Dobbs et al., fractional lengthening of the iliopsoas tendon at the musculotendinous junction, seems to have been effective in relieving symptoms while preserving hip flexion strength—snapping did not recur in any of the patients and all returned to previous levels of activity.

The major concerns of the orthopaedist presented with a patient who has symptoms of snapping hip are how to identify the etiology of the snapping and whether surgical treatment will be effective. This report of nine adolescents who had the internal type of snapping hip provides practical answers to the questions:

• How does one make the diagnosis? With use of the clinical examination and the history.
• What imaging studies are necessary? None, although radiographs and magnetic resonance imaging scans can be used to rule out intra-articular pathology.
• Will surgical treatment improve symptoms? For patients in whom the iliopsoas tendon is the cause of snapping hip, surgical lengthening can successfully relieve symptoms.

Snapping hip is a clinical diagnosis that gives us the opportunity to "think out of the box" rather than revert to our usual dependence on technology. Often we are too quick to order an MRI, a bone scan, or an ultrasound to provide a quick, definitive diagnosis. This report on the internal type of snapping hip not only makes us more aware of the condition, but also reminds us that some conditions can best be diagnosed simply by taking a careful history and performing a thorough examination of the patient.

*The author did not receive grants or outside funding in support of his research or preparation of this manuscript. He did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the author is affiliated or associated.

References

1. Allen WC, Cope R. Coxa saltans: the snapping hip revisited. J Am Acad Orthop Surg. 1995;3:303-8.
2. Jacobson T, Allen WC. Surgical correction of the snapping iliopsoas tendon. Am J Sports Med. 1990;18:470-4.
3. Zoltan DJ, Clancy WG Jr, Keene JS. A new operative approach to snapping hip and refractory trochanteric bursitis in athletes. Am J Sports Med. 1986;14:201-4.