Parafoveal chondral defects associated with femoroacetabular impingement.
BACKGROUND
Cam-type, pincer, and mixed femoroacetabular impingement (FAI) are accepted causes of labral and acetabular rim injury; however, the abnormal contact stresses associated with motion may damage other areas of the hip. Although cartilage damage to the femoral head has been reported previously in athletes, FAI-associated focal parafoveal chondral defects differ from previously reported lesions and represent a rare manifestation of the complex pathomechanics associated with FAI.


OBJECTIVE
We describe the clinical, radiographic, and surgical characteristics of a rare focal anterolateral parafoveal femoral chondral defect associated with FAI.


METHODS
We retrospectively reviewed 10 patients with symptomatic FAI diagnosed with this unique focal defect confirmed at the time of surgical dislocation. Patients presented with hip pain, clinical findings of FAI, and, frequently, with an identifiable lesion on MRI arthrography. The minimum clinical followup was 12 months (mean, 29 months; range, 12-72 months).


RESULTS
The consistent characteristics of these lesions associated with FAI differ from previously reported femoral chondral damage reported after hip dislocation or lateral impact in that there was no discrete injury such as a fall or dislocation/subluxation, no associated traumatic femoral lesion, and all were localized to the posterosuperior femoral head. Eight of 10 were diagnosed preoperatively using MR arthrography.


CONCLUSIONS
Despite radiographic similarities to findings of osteoarthritis and osteonecrosis, these FAI-associated femoral chondral defects were amenable to surgical reconstruction using first- or second-generation cartilage repair techniques during surgical treatment of impingement. The etiology of these lesions may be related to complex intraarticular forces generated by FAI-associated transient hip subluxation or forceful nonconcentric motion.


METHODS
Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
Department of Orthopaedic Surgery, William Beaumont Hospital, 3535 W 13 Mile Road #744, Royal Oak, MI 48073, USA. zaltzira@gmail.com
Ira
I
Zaltz
Michael
M
Leunig
D000293:Adolescent; D000328:Adult; D001175:Arthrography / Q000379:methods; D005260:Female; D057925:Femoracetabular Impingement / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology / Q000601:surgery; D005270:Femur Head / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008824:Michigan; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D013557:Switzerland; D016896:Treatment Outcome; D055815:Young Adult