Journal of Innovative Clinical Trials and Case Reports

Abstract

Introduction: Knowles pins were historically used for femoral neck fractures and slipped upper femoral epiphysis (SUFE). Decades later, complications such as bursitis, implant prominence, migration, or difficult extraction may arise.

Case Presentation: AA 52-year-old female (BMI 36), HIV-positive but virally suppressed, presented with severe right hip osteoarthritis (Tönnis grade 3) and chronic left trochanteric bursitis from Knowles pins inserted in 1989. Knowles pin removal was performed first. Each pin demonstrated a completely flattened head with no recess or slot for engagement, making standard extraction techniques impossible. All four pins were removed using a vice grip. A right posterior-approach total hip arthroplasty followed uneventfully. At six weeks, she was pain-free bilaterally and mobilising unaided.

Conclusion: Knowles pins retained for more than 30 years may be extremely difficult, or even impossible, to remove using conventional extraction techniques. Chronic in-situ implants often undergo substantial deformation, bony overgrowth, and loss of the original drive interface, making standard removal tools ineffective. When a patient requires a contralateral total hip arthroplasty (THA), removal of the long-standing hardware can significantly enhance post-operative rehabilitation by reducing trochanteric pain, improving mobility, and eliminating mechanical irritation from the retained implants.