Thigh Pain After Hip Arthroplasty: Screening the Differential
A 72-year-old woman is 9 weeks post elective total hip arthroplasty via a posterior approach for osteoarthritis. She completed formal PT at 6 weeks and now returns with new anterior thigh pain that began insidiously 10 days ago, worse with weight-bearing and with rising from a low chair, and mildly better with rest. She denies a fall. Her surgical incision is well healed. Hip flexion is 95 degrees (was 110 at discharge), passive extension is 5 degrees short of neutral, and internal rotation reproduces a deep anterior groin ache. She has 4/5 hip flexor strength and a new antalgic gait. She reports low-grade fever for 3 days and night pain that wakes her. Her D-dimer is pending. She asks whether she should just "push through" with more strengthening.
1. What is your leading hypothesis, and what findings in this case raise concern beyond a typical postoperative muscle strain?
Read the worked answer
A postoperative periprosthetic joint infection must be the leading concern, with aseptic loosening and occult periprosthetic fracture as secondary considerations. Red flags here are the constellation, not any single finding:
- New night pain that wakes her and pain at rest
- Fever (even low grade) at 9 weeks
- A functional decline (loss of 15 degrees of flexion, new antalgic gait) rather than a plateau
- Pain that is insidious and progressive without a traumatic mechanism
A muscle strain would not produce fever, night pain, or progressive loss of range. Her request to "push through" should be declined until medical screening is complete. Note that D-dimer is more useful for thromboembolic disease than for infection; do not let a pending D-dimer delay the referral conversation.
2. How would you manage this visit and communicate with the surgeon? Include what you would and would not do in the session.
Read the worked answer
Do not load the hip, perform resisted strengthening, or apply aggressive stretching. Perform only a limited, gentle exam needed to document the baseline (active range, neurovascular screen, gait observation).
Actions:
- Same-day contact with the orthopaedic surgeon's office, describing the new pain pattern, fever, night pain, and loss of range, and requesting urgent evaluation (aspiration/labs per their protocol).
- Document objective findings and the referral in the record.
- Give the patient clear return precautions (worsening fever, inability to bear weight, wound drainage, systemic symptoms) and instructions not to progress exercise until cleared.
- Clarify that this is not a failure of her rehabilitation and that pausing is appropriate.
This is a case where the correct "intervention" is timely medical referral, not a therapeutic exercise progression.