[Reflections on a small series of cementless total hip prostheses]

We report on our series of 48 patients with uncemented hip prostheses, with an average follow-up of 3 years. The clinical results, according to the Merle d'Aubigné's classification, are comparable to those obtained with cemented prostheses except for transitory pain, very often localized to the lateral aspect of the thigh, which seems to be correlated with the bone adaptation to the implant. Radiological findings are valuable in the assessment of long-term results with uncemented prostheses. During the operation, it is of utmost importance that the surgeon obtain a very tight fit of the prosthesis into the bone, which must be confirmed on postoperative X-ray. Under such conditions, the radiological appearance remains the same, showing a condensation line outlining the cup and absence of radiolucent lines along the stem. On the other hand, cortical thickening, bony condensation around the tip of the stem and sclerotic lines are the radiological evidence of bone adaptation to the prosthesis. They are not indicative of a less good result. Finally, radiolucent lines wider than 1 millimeter, extending along the stem, or a progressive sinking of the femoral component are the radiological signs of implant instability. In these rare cases, the prognosis may be compromised.