Abstract
Objective
While the short-stem design is not a new concept, interest has risen with increasing utilization of less invasive techniques. Especially, short stems are easier to insert through the direct anterior approach. In the radiographic evaluation of patients who underwent primary uncemented total hip arthroplasty (THA) using a TaperLoc Microplasty femoral component (Biomet, Warsaw, IN, USA), cortical hypertrophy was occasionally detected on three-month postoperative radiographs. The purpose of this study was to evaluate the radiographic changes associated with cortical hypertrophy of the femur three months postoperatively.
Methods
Between May 2010 and September 2014, 645 hips in 519 patients who received the TaperLoc Microplasty stem were evaluated. Six hips in four patients were lost to follow-up. Finally, 639 hips in 515 patients were included in this study; 248 hips underwent bilateral simultaneous THA and 391 hips underwent unilateral THA. There were 103 males and 412 females (average age, 63 ± 10.1 years; average height, 156 ± 8.13 cm; and average weight, 58 ± 12.2 kg). The postoperative radiographs immediately taken after the operation and three months postoperatively were compared. We evaluated cortical hypertrophy around the stem. Cortical hypertrophy >2 mm on anterior-posterior X-ray was defined as “excessive periosteal reaction” (Figure 1).
Results
Twenty-four (3.76%) of the 639 hips had an excessive periosteal reaction. Eight (1.25%) hips underwent bilateral simultaneous THA and sixteen (2.5%) hips underwent unilateral THA. With regard to the prevalence of the excessive periosteal reaction, there were no significant differences between the patients who underwent the unilateral procedure compared with those who underwent the bilateral procedure. Of these 24hips, 12 (50%) showed thigh pain in patients after surgery. The patients with an excessive periosteal reaction had an average age of 66 ± 9.02 years, an average height of 157 ± 6.4 cm, and an average weight of 61 ± 10.3 kg. There were no significant differences in age, height, and weight between the patients with an excessive periosteal reaction and all study patients. The thigh pain resolved spontaneously within three months after surgery in all patients, and no patient required revision surgery. Six (0.94%) hips had femoral periprosthetic fractures in the early postoperative period.
Conclusions
Excessive periosteal reaction, which was defined as cortical hypertrophy >2 mm on anterior-posterior X-ray three month postoperatively, occurred in 3.75% of the patients who received the TaperLoc Microplasty stem. Thigh pain occurred in half of the patients who had an excessive periosteal reaction. We speculated that this reaction was caused by the concentration of the torque or vertical load on the limited area of the femur in the early postoperative period. This stress was accompanied by femoral periprosthetic fractures in the early postoperative period, and patients without femoral periprosthetic fractures experienced an excessive periosteal reaction with thigh pain.
