This paper by Engh et al. develops and validates a quantitative radiographic scoring system for assessing fixation of cementless femoral components. It assigns numeric values to major and minor radiographic signs, then tests the score against histologically confirmed cases and 1005 clinical cases. The goal is to predict osseointegration versus fibrous stabilization versus gross instability from plain radiographs alone.
Every cementless THA follow-up film should be read systematically, not just eyeballed for obvious loosening.
When you see a patient with hip pain after cementless THA, apply the Engh score: absent reactive lines around the porous surface and endosteal spot welds point toward osseointegration; extensive reactive lines in over half the porous-surfaced Gruen zones, progressive particle shedding, and calcar hypertrophy beneath a collar point toward failure.
A score below -10 means gross instability. The authors demonstrated that intraoperative stability testing is unreliable — if you take a patient back with a negative fixation score, revise the femoral stem even if it feels stable when you stress it.
Calcar atrophy on a cementless stem is not bone loss to worry about. It is a radiographic sign of successful osseointegration and distal load transfer. Do not confuse it with periprosthetic bone loss from instability.
This paper by Engh et al. develops and validates a quantitative radiographic scoring system for assessing fixation of cementless femoral components. It assigns numeric values to major and minor radiographic signs, then tests the score against histologically confirmed cases and 1005 clinical cases. The goal is to predict osseointegration versus fibrous stabilization versus gross instability from plain radiographs alone.
Every cementless THA follow-up film should be read systematically, not just eyeballed for obvious loosening.
When you see a patient with hip pain after cementless THA, apply the Engh score: absent reactive lines around the porous surface and endosteal spot welds point toward osseointegration; extensive reactive lines in over half the porous-surfaced Gruen zones, progressive particle shedding, and calcar hypertrophy beneath a collar point toward failure.
A score below -10 means gross instability. The authors demonstrated that intraoperative stability testing is unreliable — if you take a patient back with a negative fixation score, revise the femoral stem even if it feels stable when you stress it.
Calcar atrophy on a cementless stem is not bone loss to worry about. It is a radiographic sign of successful osseointegration and distal load transfer. Do not confuse it with periprosthetic bone loss from instability.