A tapered titanium femoral stem inserted without cement in a total hip arthroplasty. Radiographic evaluation and stability.

The results of 416 total hip arthroplasties performed in 372 patients with insertion of a Mallory-Head titanium femoral component without cement were reviewed retrospectively, to determine the stability and the radiographic parameters of stability for this type of stem. The average duration of clinical and radiographic follow-up was 3.7 years (range, 2.0 to 6.5 years). No revisions were performed to treat instability of the stem, pain, or osteolysis by the time of the latest follow-up examination. Although the clinical results were excellent, the radiographic signs of fixation that have been well described for chromium-cobalt stems were frequently absent. So-called endosteal spot welds, commonly seen in association with long, extensively coated stems, were seen infrequently. Resorptive bone-remodeling rarely extended beyond zones 1 and 7 of Gruen et al. Both endosteal and periosteal distal cortical hypertrophy was common, but the cause was unknown. Osteolysis of the distal aspect of the femur, shedding of the porous coating, and breakage of the stem were not seen. Forty-four stems (11 per cent) had initial subsidence; however, it nearly always stabilized within six months postoperatively and did not affect the eventual stability at the time of the short-term follow-up. The short-term clinical outcome confirmed the stability of these stems that had been determined from the radiographic findings and the lack of revisions. At the latest follow-up examination, 323 (87 per cent) of the patients (362 [87 per cent] of the hips) had no or slight pain in the lower limb over-all and only twenty-two (6 per cent) of the patients (twenty-seven [6 per cent] of the hips) had pain in the thigh. This tapered titanium femoral component appears to provide excellent short-term stability, without resorptive bone-remodeling, osteolysis, or a high prevalence of pain in the thigh. Radiographic evaluation of stability of this stem is clearly different from that of chromium-cobalt stems-particularly extensively coated anatomic medullary locking stems-in that so-called spot welds and severe resorptive bone changes were uncommon and distal cortical hypertrophy was common.