Few complaints in sports medicine get misread as often as groin pain in a young athlete. It gets labeled a hip flexor strain, a groin pull, or a core injury, and the athlete goes back to training with a stretching program that never fully resolves it.
Months later, the pain is still there, deep in the front of the hip, worse after a long car ride or a hard change-of-direction session. In a meaningful share of those cases, the cause lies in the shape of the bone itself, with the muscles largely secondary, and understanding the mechanics behind persistent hip pain changes the entire treatment conversation.
Cam morphology, often called a cam lesion, sits at the center of that conversation. It's a bump of extra bone where the femoral head meets the femoral neck, turning a smoothly spherical ball into something closer to a pistol grip.
For an athlete who spends much of their training time in deep hip flexion, that small change in geometry has outsized consequences, which is why orthopedic surgeons like Michael Gaudiani II approach a stubborn groin complaint as a structural question first.
Image Source: Unsplash
Inside the Joint: What a Cam Lesion Actually Does
A healthy femoral head is nearly spherical and turns inside the acetabulum with clearance all around. A cam lesion takes away much of that clearance at the front of the neck. When the hip flexes and rotates inward, as it does in a squat, a hockey stride, a goalkeeper's dive, or a deep lunge, the aspherical part of the head gets driven into the rim of the socket when it should be gliding beneath it.
The labrum, the fibrocartilaginous ring that seals the joint, and the articular cartilage just behind it absorb the contact. Across thousands of repetitions, the labrum frays and tears, and the cartilage starts to separate from the bone underneath in a pattern clinicians call delamination. Damage clusters in the anterosuperior quadrant of the socket, so patients often feel pain in the front of the groin, away from the lateral spot they usually point to when they say hip.
For the same reason, the problem keeps progressing instead of settling down. A strained muscle heals, but a mismatch in joint shape stays put, and each season of high-flexion loading adds to whatever chondrolabral damage is already there.
Why the Lesion Shows Up in Athletes
Many patients assume cam morphology is congenital, but the prevailing evidence suggests it develops during adolescence. At the same time, the growth plate at the top of the femur is still open and responsive to load. High-impact, high-rotation sport during those years seems to change how the bone remodels around the physis, leaving a larger, flatter head-neck junction by the time the skeleton reaches maturity.
The epidemiology fits that picture. Soccer, ice hockey, basketball, and elite-level track and field all show higher rates of cam morphology than the general population, with the rates tilted toward athletes who specialized early and trained year-round as teenagers. Orthopedics has few clearer examples of adolescent training load shaping adult joint anatomy, and surgeons such as Michael Gaudiani II see the pattern reflected in the sporting histories of patients who arrive in clinic with unresolved groin pain in their twenties and thirties.
There's a complication, though, and it often gets lost in the clinic. Plenty of athletes with cam morphology feel perfectly fine. Screening studies of asymptomatic players regularly find it in a sizable share of the squad, so bone shape alone doesn't amount to a diagnosis.
The Difference Between a Finding and a Syndrome
Few distinctions in the workup matter as much as this one, and unnecessary surgery often starts when it's ignored. Femoroacetabular impingement syndrome (FAIS) requires three things together: symptoms the patient can describe, clinical signs on examination, and imaging findings that explain them. Imaging by itself describes anatomy and can't establish pathology.
When clinicians know what to listen for, the symptom pattern is fairly consistent. Athletes describe deep anterior groin pain and will often cup the side of the hip between thumb and forefinger, a gesture known as the C-sign.
Long periods of sitting make it worse, as does deep squatting. Some report catching or clicking, which usually points to a labral tear more than to the bone. On examination, internal rotation is measurably reduced with the hip flexed to ninety degrees, and the flexion-adduction-internal rotation maneuver brings on the familiar pain.
Radiographs and MRI then confirm what the history suggests. The alpha angle, measured on a Dunn lateral view or on radial MRI sequences, quantifies how far the head-neck junction deviates from spherical, with values above roughly fifty-five to sixty degrees generally considered cam morphology. MRI also shows the condition of the labrum and cartilage, which plain radiographs can't show.
Ruling Out the Conditions That Mimic It
Anterior hip and groin pain has a long differential, and skipping it leads to procedures that miss the actual pain generator. Adductor and iliopsoas pathology, athletic pubalgia, femoral neck stress fractures in distance runners, referred pain from the lumbar spine, and hip instability in athletes with generalized laxity can all look alike on presentation. Cam morphology can show up alongside any of them, and that overlap is where clinicians get caught.
A diagnostic intra-articular injection is often the best tiebreaker available. If a small volume of local anesthetic placed inside the joint substantially relieves the pain, the source is intra-articular. If it does nothing, the problem lies elsewhere, and reshaping bone won't touch it. Careful sequencing of this kind, working through what the evidence supports before deciding when surgery actually helps, is what separates durable outcomes from disappointing ones.
Where Rehabilitation Ends and Surgery Begins
For most symptomatic athletes, structured physical therapy comes first, and it deserves a genuine trial before anyone schedules a procedure. Its goals are specific to this problem: build control through the lumbopelvic complex, strengthen the deep hip rotators and abductors that stabilize the femoral head, retrain movement patterns so athletes spend less time at end-range flexion, and temporarily modify the training activities that provoke symptoms. Many athletes improve enough on this pathway alone to return to their sport without surgery.
If a well-run rehabilitation program fails and imaging shows correctable pathology, arthroscopic treatment becomes a reasonable next step. The procedure deals with both sides of the problem, reshaping the head-neck junction to restore clearance and repairing or reconstructing the damaged labrum to preserve the joint seal.
Randomized trials comparing arthroscopy with supervised physiotherapy for impingement syndrome have favored surgery on patient-reported hip scores, though by a moderate margin, and results depend heavily on patient selection.
Selection matters more than technique, and it's where the judgment of a surgeon such as Michael Gaudiani II carries the most weight. Athletes with preserved joint space and limited cartilage damage generally do well, with return to sport commonly measured at four to six months for straightforward cases and longer for cutting and contact sports. Athletes who already show established arthritic change respond poorly, since reshaping bone can't restore cartilage that is already gone.
The Long View on Hip Longevity
This anatomy draws so much research attention because it predicts outcomes decades later. Cam morphology is among the most consistently identified mechanical risk factors for hip osteoarthritis, and the damage builds quietly over years when an athlete is still performing well.
Seen that way, the clinical question extends past getting a player back for the second half of the season to whether the joint will hold up for the next thirty years.
Whether early surgery meaningfully alters that trajectory is still an open question, and honest practitioners admit as much. What's settled is that the athlete is better served by recognizing the pattern early, managing training load sensibly through adolescence, and avoiding procedures that don't match the pathology than by another round of stretching for a strain that was never a strain.
About Michael Gaudiani II
Michael Gaudiani II is an orthopedic surgeon whose clinical and academic interests center on sports medicine and treating joint injuries in active patients. His work has focused on the surgical and non-surgical management of conditions affecting the hip, knee, and shoulder, with particular attention to joint preservation in younger patients whose remaining decades of activity depend on the decisions made early in the course of an injury.
He completed his medical training at Case Western Reserve University School of Medicine and his orthopedic surgery residency in Detroit, and he continues to write and speak on evidence-based approaches to musculoskeletal care.
