Three Weeks of Groin Pain in a Cadet Who Wants a Note to Keep Training
Devon is a 21-year-old ROTC cadet and club soccer player with 3 weeks of deep left groin pain that began without any specific injury. It now aches at rest and wakes him at night. He runs about 40 miles per week plus ruck marches. Pain is reproduced at end-range hip flexion; log rolling is only mildly uncomfortable; FADIR is positive and the hop test is positive on the left. He has been treating it as a groin strain with stretching and keeps running because 'it loosens up after the first mile.' He is afebrile, with no hernia and a normal testicular exam. He asks for a note so he can keep training until his appointment in three weeks.
1. Give your differential and state which diagnosis must be excluded first, with the imaging you would order and why.
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Differential: femoral neck stress fracture, femoroacetabular impingement with labral pathology, adductor strain, sports hernia/inguinal disruption, sacroiliac dysfunction, lumbar radiculopathy, avascular necrosis, and - given night pain - infection or tumor.
Must exclude: femoral neck stress fracture. The features that point there rather than to muscle are insidious onset with no inciting event, pain at rest, night pain, a very high repetitive load (40 miles plus load carriage), and the classic 'it loosens up after the first mile' pattern of bone stress. Provocative tests are neither sensitive nor specific; a mildly positive log roll does not reassure.
Imaging: MRI of the hip without contrast, today. Radiographs are frequently normal early, and 'repeat films in three weeks' is the wrong answer in a patient with night pain and a high training load. If MRI is unavailable, a limited CT or bone scan can substitute, but MRI is the study that characterizes the fracture line and distinguishes compression from tension-sided involvement. Do not accept a clinical label of groin strain and allow continued running without imaging.
2. How does the specific anatomy of the femoral neck change management?
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Location determines urgency.
- Tension-sided (superolateral) fractures are pulled apart by normal loading. They carry a substantial risk of displacement, avascular necrosis, nonunion, and - in a 21-year-old - a possible arthroplasty. Management is strict non-weight-bearing, immediate orthopedic referral, and usually prophylactic internal fixation even when the line is incomplete.
- Compression-sided (inferomedial) fractures are stable under load. In a compliant, non-displaced patient they can often be managed nonoperatively with strict non-weight-bearing, crutches, and serial imaging, converting to surgery if the fracture propagates or symptoms persist.
Either way: no running, no marching, no impact until the location and extent are known, and screen the contralateral hip clinically, since bilateral involvement occurs.
The other judgment point is metabolic. A stress fracture in a 21-year-old male warrants checking vitamin D, calcium intake, energy availability, sleep, and testosterone if there are other suggestive features - a fracture here is a symptom, not just an overuse mishap. A displaced femoral neck fracture in this patient is a life-altering event, and the imaging report - not the athlete's training goals - sets the timeline.
3. He insists on a note to continue training. What do you say, and what does the recovery course look like?
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Do not write the note. Explain plainly: the concern is a fracture through the neck of the femur, and if it displaces he risks avascular necrosis, permanent hip damage, and possibly an early hip replacement at 21. Frame it as protecting his career rather than ending it - a two-to-four-week delay for imaging is small compared with months of recovery after a displaced fracture.
Now: crutches, strict non-weight-bearing on that side, urgent imaging, orthopedic referral, and no ruck marching or running regardless of how he feels. Document the counseling and the advice given.
Recovery course: nonoperative compression-sided injuries typically require 6–12 weeks of protected weight-bearing with serial imaging before walk-run progression; tension-sided injuries treated with fixation generally require 3–6 months before return to running, with sport return later and contingent on imaging and pain-free loading.
Address the drivers: the recent increase in mileage, load carriage, footwear, gait, sleep, and energy availability. Build the return on a graded mileage progression, and set expectations that 'loosening up after the first mile' is a warning sign, not a warm-up.