Subradiological cam deformity of the head-neck junction: an occult cause of hip pain and chondrolabral damage.

PURPOSE: The goal of this study was to determine how frequently the conventionally defined "idiopathic" chondrolabral hip injuries are associated with subradiological cam deformities of the head-neck junction and whether a protective femoral osteochondroplasty may improve the outcome of their arthroscopic treatment.
METHODS: All the non-arthritic or pre-arthritic painful hips diagnosed as having a primary chondrolabral injury were retrospectively evaluated. Coxometric data, clinical history and physical findings were reviewed to rule out any possible secondary lesion. The medical records of the selected cases were analyzed as for imaging features, surgical findings and post-arthroscopy outcome.
RESULTS: Three cases out of 79 chondrolabral injuries were identified as "primary" on the basis of the preoperative assessment. All the three patients were female in their fourth decade and showed a joint damage consistent with undetected cam FAI (cartilage delamination in the anterolateral acetabular quadrant, minor pathology of the adjacent labrum with or without chondrolabral separation, abrasion signs and herniation pits along the anterolateral head-neck junction). The first patient received a simple chondrolabral treatment whose benefits deteriorated few months after surgery; the second patient underwent chondrolabral repair and femoral osteochondroplasty and is still pain-free; and the third patient had a beneficial revision arthroscopy for femoral osteochondroplasty after prior unsuccessful chondrolabral surgery.
CONCLUSIONS: If a chondrolabral injury of the hip is associated with MR arthrographic and arthroscopic indirect signs of cam FAI, a subradiological head-neck deformity should be considered despite normal alpha angles. In such cases, a protective femoral osteochondroplasty may increase the success rate of the chondrolabral repair. LEVEL OF EVIDENCE: IV.