Rare Sliding Hip Screw Migration Poses Life-Threatening Risks to Pelvic Vessels: Two Cases Highlight

Richard Laurence Donovan, Musculosketal Research Unit, University of Bristol Medical School, Bristol, UK, and colleagues reported two rare cases involving intrapelvic migration of the SHS lag screw caused by non-unions, posing a threat to the iliac vessels. They provided an up-to-date review of the literature, offering insights into the mechanisms by which a lag screw may migrate and proposing strategies to prevent this complication.

Patient 1, an 80-year-old woman, presented with persistent pain in her left hip and difficulty mobilizing. She had undergone SHS fixation for a left-sided trochanteric neck of femur fracture five months earlier and spent weeks in a rehabilitation center with ongoing physiotherapy. Still, she continued to experience pain since her surgery. Her medical history included ischemic heart disease, a previous cardiac arrest, and atrial fibrillation (AF). Her mental status was intact, with a score of 10/10 on the abbreviated mental test, and her life expectancy remained good.

The patient was seen in the outpatient clinic two months post-surgery and showed progress in recovery. At her 18-month follow-up, a telephone consultation was held with her daughter due to her declining health. She had moved to a care home, mobilized short distances with a Zimmer frame, and was mostly housebound. Aside from a shuffling gait, she reported no hip complaints. Given her overall health and difficulties attending the clinic, she was discharged, and she has since passed away.

Patient 2, another woman in her 80s, was referred to a tertiary center with a three-week history of right-sided hip pain, which worsened over the last few days. She retained a small amount of discomfort with a straight leg raise. She had previously undergone SHS fixation for a right-sided trochanteric neck of femur fracture seven years ago. Fifteen months post-surgery, she experienced right medial thigh tenderness, with imaging revealing the failure of the most distal plate screw by breakage, managed without additional surgery. Her medical history included AF, congestive cardiac failure, abdominal aortic aneurysm, chronic kidney disease, hypertension, and coeliac disease. She lived independently with minimal assistance twice weekly, using a Zimmer frame for mobility but rarely leaving her home.

This patient was seen in the outpatient clinic two months post-surgery and was recovering well, mobilizing with a wheeled frame and reporting only occasional right hip ache. Radiographs confirmed no further lag screw migration. She preferred to avoid surgery as her symptoms were managed, and she was discharged with an open appointment.

The authors emphasize that orthopedic surgeons should remain aware of this rare but serious complication, as intrapelvic screw migration can pose a threat to the iliac vessels. They highlight the importance of using contrast-enhanced cross-sectional imaging to assess proximity to neurovascular structures. If necessary, collaboration with general or vascular surgeons should be considered to plan the surgical approach for intrapelvic screw retrieval.

"Adhering to manufacturer operative technique guides and avoiding skipped surgical steps are crucial. Additionally, surgeons should ensure guidewires do not penetrate the femoral head and that the femoral head and neck are not over-reamed," they concluded.

Reference:

Donovan RL, Jiang M, Bassett J, et al. Rare intrapelvic migration of a sliding hip screw after hip fracture fixation. BMJ Case Reports CP 2024;17:e261689.