Short stem total hip arthroplasty with the direct anterior approach demonstrates suboptimal fixation

Abstract

Purpose: Short stems use has increased substantially despite variable results reported in the literature. The purpose of this study was to report the rate of complications using a short stem implanted through the direct anterior approach (DAA), and to evaluate mid-term clinical and radiological results focusing on femoral stem fixation.

Methods: Between April 2009 and November 2014, 698 elective total hip arthroplasties (THAs) were performed using a fully hydroxyapatite-coated short stem (AMIStem-H®). The mean age was 65.7 years (SD 12.6). Patients were invited for clinical and radiological evaluation, and to complete patient-reported outcomes questionnaires at two and five years after surgery. The mean follow-up was 6.2 years (range 2-9.73 years).

Results: During the study period, 59 (8.5%) patients died and 24 (3.4%) were lost to follow-up. There were six (0.9%) dislocations and 12 (1.7%) fractures, seven occurred intra-operatively. Twenty-nine (4.2%) THAs required revision surgery. Eleven THAs were revised for aseptic loosening of the stem at a mean 4.9 years (1.2-7.3 years). Five years after surgery, radiographs of 324 THAs (324/425 eligible = 76.2%) were available. Stem subsidence ≥ 2 mm was present in 42 cases (12.9%), proximal radiolucencies in 101 hips (31.5%), cortical thickening in 52 (16.0%), and a pedestal in 219 (67.6%). An Engh score between - 10 and 0 was associated with lower HHS pain subscore (p = 0.005), a higher risk of stem revision for aseptic loosening (18.8% vs. 2.7%; p = 0.008), and was more frequent in younger patients with ASA score 1.

Conclusion: Patients presenting radiological alterations at five years had an increased risk of revision for aseptic stem loosening and also inferior clinical results. Our study warrants further continued scrutiny of mid- and long-term survivorship of the AMIStem-H®, with radiological results at five years indicating suboptimal fixation of the stem in younger and active patients.

Keywords: Complications; Loosening; Short stem; Total hip arthroplasty.

Fig. 1

Flowchart

Fig. 2

Kaplan-Meier failure function of Versafit cup/AMIS stem uncemented

Fig. 3

Distribution of detected radiological signs at 5-year FU

Fig. 4

Illustrative case of aseptic loosening of the femoral stem of a 57-year-old patient who had a total hip replacement on his left hip. Radiological features of progressive loosening and mobilization of the femoral stem at two and five year follow-up. Joint aspiration was negative for bacteria as well as deep tissue cultures obtained from intra-operative samples. The hip was subsequently revised with a cemented femoral stem

Fig. 5

Harris Hip Subscore pain according to Engh score category. Engh score dichotomized > 0 and ≤ 0: < − 10 “unstable” and – 10–0 = “suboptimum but stable” vs. 0–10 = “ingrowth suspected” and > 10 = “bone ingrowth”; Harris Hip Score: 0–44 = no pain. When comparing HHS pain in Engh > 0 and ≤ 0, there were proportionally more patients having a low HHS pain in the ≤ 0 group. p = 0.037 chi-square linear by linear