Femoral impingement in maximal hip flexion is anterior-inferior distal to the cam deformity in femoroacetabular impingement patients with femoral retroversion : implications for hip arthroscopy

AIMS

Femoroacetabular impingement (FAI) patients report exacerbation of hip pain in deep flexion. However, the exact impingement location in deep flexion is unknown. The aim was to investigate impingement-free maximal flexion, impingement location, and if cam deformity causes hip impingement in flexion in FAI patients.

METHODS

A retrospective study involving 24 patients (37 hips) with FAI and femoral retroversion (femoral version (FV) < 5° per Murphy method) was performed. All patients were symptomatic (mean age 28 years (SD 9)) and had anterior hip/groin pain and a positive anterior impingement test. Cam- and pincer-type subgroups were analyzed. Patients were compared to an asymptomatic control group (26 hips). All patients underwent pelvic CT scans to generate personalized CT-based 3D models and validated software for patient-specific impingement simulation (equidistant method).

RESULTS

Mean impingement-free flexion of patients with mixed-type FAI (110° (SD 8°)) and patients with pincer-type FAI (112° (SD 8°)) was significantly (p < 0.001) lower compared to the control group (125° (SD 13°)). The frequency of extra-articular subspine impingement was significantly (p < 0.001) increased in patients with pincer-type FAI (57%) compared to cam-type FAI (22%) in 125° flexion. Bony impingement in maximal flexion was located anterior-inferior at femoral four and five o'clock position in patients with cam-type FAI (63% (10 of 16 hips) and 37% (6 of 10 hips)), and did not involve the cam deformity. The cam deformity did not cause impingement in maximal flexion.

CONCLUSION

Femoral impingement in maximal flexion was located anterior-inferior distal to the cam deformity. This differs to previous studies, a finding which could be important for FAI patients in order to avoid exacerbation of hip pain in deep flexion (e.g. during squats) and for hip arthroscopy (hip-preservation surgery) for planning of bone resection. Hip impingement in flexion has implications for daily activities (e.g. putting on shoes), sports, and sex.Cite this article: Bone Joint Res 2023;12(1):22-32.

Extra-articular hip impingement: a review of the literature

Hip and groin pain is a common clinical problem. Multiple causes can generate hip or groin pain, often sharing clinical and demographic characteristics. Diagnostic imaging tests play an important role in the etiological diagnosis. New forms of extra-articular hip impingement have recently been recognized as a cause of hip pain and limited function especially in young active patients. These conditions include ischiofemoral impingement, anterior inferior iliac spine and subspine impingement, iliopsoas impingement and greater trochanteric-pelvic impingement. In general, they are caused by a mechanical conflict with an abnormal or excessive contact between the proximal femur and pelvis and/or soft tissue between them. In this manuscript we review the physiopathology, clinical presentation, the most common radiologic findings and treatment of these forms of extra-articular hip impingement.

Avulsion fracture of anterior inferior iliac spine complicated by hypertrophic malunion causing femoroacetabular impingement: Case report

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Hypertrophic malunion of anterior inferior iliac spine causing impingement.

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Failed conservative management.

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Surgical excision of hypertrophic fragment have been done to relieve the symptom.

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First case in Qatar.

Introduction

Avulsion fractures of the anterior inferior iliac spine are uncommon and such injuries are caused by the sudden forceful contraction of the straight head of rectus femoris muscle while the hip is hyperextended and the knee is flexed.

Case presentation

This case report describes the condition of 17 year old male footballer who complained of pain in the right groin for duration of 2 years after being involved in forceful sport activity. Detailed history, clinical examination, X-rays and CT scan revealed hypertrophic malunion of avulsion fracture of anterior inferior iliac spine causing an extra-articular type of femoroacetabular impingement. The patient was surgically treated when conservative management was unsuccessful.

Discussion

This is the first case of hypertrophic malunion of avulsion fracture of anterior inferior iliac spine with femoroacetabular impingement that has been recognized in Qatar. The patient was surgically treated in order to relieve symptoms and avoid osteoarthritis.

Conclusion

Malunited avulsion fracture of anterior inferior iliac spine can cause extra-articular femoroacetabular impingement.