Femoroacetabular Impingement (FAI)

Impingement symptoms are commonly attributed to a groin strain or hip tightness for months before the diagnosis is made. The pattern below warrants evaluation.

• Motion-related or position-related pain in the groin or front of the hip, sometimes felt in the buttock or thigh
• A pinching sensation deep in the hip when squatting, sitting low, or bringing the knee toward the chest
• Pain with prolonged sitting, which makes driving and desk work provocative
• Noticeably reduced hip rotation compared with the other side, particularly internal rotation when the hip is flexed
• Clicking, catching, or a sense of the hip locking during movement
• Stiffness that limits athletic positions such as a deep squat, a hockey stride, or a dance turnout
• Difficulty with cutting, pivoting, or explosive acceleration in sport

If groin pain has persisted beyond several weeks despite rest, or if your hip is catching or giving way, call our office for an evaluation. Adolescent and young adult athletes deserve particular attention, since research Dr. Christoforetti co-authored documented distinct intra-articular hip injury patterns in adolescent athletes across a five-year multicenter cohort (McGovern et al., [Int Orthop](https://pubmed.ncbi.nlm.nih.gov/32591961/)).

Because morphology alone is not a diagnosis, the evaluation is built to establish whether the shape of your hip is actually causing your symptoms.

Physical examination. The FADIR test, combining flexion, adduction, and internal rotation, is the most commonly used maneuver. It is very sensitive, with pooled sensitivity around 0.96, which means a negative test makes the diagnosis unlikely. Its specificity is poor, pooled near 0.11, which means a positive test on its own proves very little. The Warwick panel described it the same way, as "sensitive but not specific." Restricted internal rotation in flexion is often the more telling finding. No single test rules the condition in, and we do not pretend otherwise.

The limits of physical examination are documented in our own research. A multicenter study Dr. Christoforetti co-authored found that manual measurement of hip range of motion shows only moderate reliability even among experienced hip preservation surgeons (Harris et al., J Hip Preserv Surg).

Radiographs. A standing AP pelvis view plus a lateral view of the femoral neck are obtained first, as the Warwick Agreement recommends, to assess hip shape and rule out other causes of pain. The alpha angle quantifies cam morphology, and the lateral center-edge angle assesses coverage. A caution on thresholds: published cutoffs for an abnormal alpha angle range from 50 to well above 90 degrees depending on the method used, and the Warwick panel declined to endorse any single number, noting that alpha angles "cannot accurately discriminate between patients with cam type FAI syndrome and asymptomatic volunteers." We read these measurements as part of a continuum, not as a pass-fail line.

Cross-sectional imaging. MRI characterizes the labrum and cartilage alongside the bony shape, and is obtained when soft tissue assessment will change the plan. CT, including three-dimensional reconstruction, is reserved for complex bony anatomy such as suspected retroversion or version abnormalities, and for surgical planning.

Diagnostic injection. When the source of pain is unclear, an image-guided anesthetic injection into the joint helps confirm whether the pain originates inside the hip.

Two findings from Dr. Christoforetti's multicenter research inform how we read imaging. Acetabular coverage exists on a spectrum from undercovered to overcovered, and outcomes differ across that spectrum (Matsuda et al., Arthroscopy). Dysplasia and impingement also coexist more often than is generally appreciated, which was documented in a large multicenter analysis of dysplasia prevalence and associated findings (Matsuda et al., Arthroscopy). Distinguishing a hip that is pinching from one that is unstable changes the treatment entirely, and getting that distinction right is central to hip preservation.

Recovery is staged and driven by healing rather than by how you feel, and protocols vary legitimately between surgeons. The outline below reflects the most consistent elements across published protocols; your specific plan governs your recovery.

The first two to three weeks are protective. Weight-bearing is partial with crutches, extended to about six weeks if cartilage restoration was performed. Motion is restricted early, commonly limiting flexion and rotation, particularly when the capsule has been repaired. This phase is a genuine safety matter rather than a comfort measure, given that premature weight-bearing accounts for about half of reported femoral neck fractures after this surgery.

From roughly three to twelve weeks, weight-bearing advances to full once your gait is normal and pain-free, motion is restored, and strengthening of the hip and core begins. Stationary cycling is usually introduced early.

Around three months, a running progression begins, typically once you can walk briskly for thirty minutes without pain. Progression changes one variable at a time, distance or speed or terrain, rather than several at once.

Return to sport generally falls between four and six months for recreational activity, though professional athletes average closer to seven months before competitive play. Expectations should be calibrated to your actual sport. Among professional athletes in the major North American leagues, about 86 percent returned to play. Among long-distance runners, 74 percent returned to running but only 37 percent returned to long-distance running specifically. That gap between returning to activity and returning to your prior level is real, and we would rather discuss it before surgery than after.