Adequate trauma of a well-fixed total hip prosthesis might cause relevant osseous injuries. Concomitant occult fractures of the implant itself are very rare. We report on two patients admitted to our institution and who were previously treated with similar types of short-stem total hip arthroplasty (THA). Both were unable to walk after an adequate trauma, although the initial admitting hospital misdiagnosed the exact diagnosis. Detailed reexamination later revealed a prosthetic neck fracture of the cement-free stem. Both patients were treated with a stem revision. In THA patient, special attention should be drawn to the implants after relevant trauma. A single examination shortly after trauma seems to be insufficient to diagnose implant-related injuries. A secondary follow-up several weeks after trauma, including at least X-rays, has to be recommended.