Hip impingement: beyond femoroacetabular

Abstract

In the last 20 years, femoroacetabular impingement has been at the forefront of clinical practice as a cause of hip pain in young adults. As arthroscopic techniques for the hip continue to evolve, the possible presence of a new group of conditions creating mechanical conflict in and around the hip joint (ischiofemoral, subspine and iliopsoas impingement) has recently been elucidated whilst interest in already known 'impingement' syndromes (pelvic-trochanteric and pectineofoveal impingement) is now revived. This article attempts to increase awareness of these relatively uncommon clinical entities by describing their pathomorphology, contact mechanics, treatment and published results available to present. It is hoped that such knowledge will diversify therapeutic options for the clinician, thereby improving outcomes in a small but not negligible portion of patients with previously unexplained persistent symptoms.

Fig. 1.

Anteroposterior pelvic radiograph following a valgus-derotational subtrochanteric osteotomy of the right hip for a malunited peritrochanteric fracture with involvement of the lesser trochanter (LT). The original injury and the valgus component of the corrective osteotomy have brought the right LT in close proximity to the ischium. Such a patient would be at risk for ischiofemoral impingement.

Fig. 2.

Clinical photograph demonstrating how combined hip extension/adduction/external rotation is performed during examination for ischiofemoral impingement. The unaffected extremity is brought forward, providing enough clearance for the hip to be adducted.

Fig. 3.

Anteroposterior plain radiograph of a 30-year-old male recreational football player. The AIISs (arrows) are at the level of (right hip) and below (left hip) the acetabular rim. Note the concurrent positive crossover signs and prominent ischial spines, suggesting apical retroversion of the acetabulae.

Fig. 4.

Close-up view of the right hip from an anteroposterior plain radiograph of a 19-year-old female with positive crossover sign. The point of crossover is marked by a blue dot. Arguably, the AIIS continues distally with round borders (black arrows) extending below the acetabular margin, potentially contributing to a false appearance of acetabular retroversion. Such a patient would require further investigation with computed tomography, to include 3-D imaging.

Fig. 5.

Arthroscopic image of a discoloured, degenerate anterior labrum with inflammation of the adjacent capsule (black arrow) (A). Probing of the chondrolabral junction reveals an early labral detachment (B). FH, femoral head; Ac, acetabulum; L, labrum.

Fig. 6.

Anteroposterior plain radiograph (A) and corresponding 3-D CT (B) of a 20-year-old man showing the full spectrum of sequelae of Perthes disease (coxa breva, coxa plana and coxa magna, relative coxa vara due to a high-riding greater trochanter, steep acetabulum) in adulthood. Both hips were affected in this patient.

Fig. 7.

With a subtrochanteric valgus osteotomy (modified Wagner-type), the greater trochanter (GT) is essentially advanced distally and laterally. Note the intentional translation at the site of osteotomy (A). Anteroposterior pelvic radiograph of a 19-year-old woman with a history of multiple previous operations for a right congenitally short femur. The GT abuts the pelvis, despite a previous GT transfer. The neck-shaft angle measures 112° (B). The patient underwent a Morscher osteotomy (intra-operative radiographs shown) which involves sliding the femoral shaft distally and laterally along an osteotomy made at the desired neck-shaft angle. The GT is osteotomized and advanced at the same angle (C). Images provided by courtesy of Dror Paley, MD, FRCS(C).

Fig. 8.

Arthroscopic image of the peripheral compartment of a hip joint showing the medial synovial fold (arrow) originating from the femoral head (FH) and inserting distally onto the capsule (C). The intimate anatomical relationship of the medial synovial fold with the zona orbicularis (ZO) is also demonstrated. FN, femoral neck.

Fig. 9.

MR arthrogram (T₂-weighted fat-suppressed sequence) of a right hip in the coronal plane, showing the medial synovial fold (arrow) adjacent to the anteromedial femoral neck.

Fig. 10.

Arthroscopic technique of resection of the medial synovial fold. The patient is the one depicted in Fig. 8. The fold (arrow) is being resected with use of a deflectable radiofrequency probe (A). Corresponding fluoroscopic image showing the position of the probe against the medial femoral neck. External rotation of the hip (shown by the prominence of the lesser trochanter) facilitates access by bringing the fold more anteriorly (B). Final appearance with the medial synovial fold completely resected (arrow) (C). FH, femoral head; FN, femoral neck; ZO, zona orbicularis.