Mid-term results of a new-generation calcar-guided short stem in THA: clinical and radiological 5-year follow-up of 216 cases

Abstract

BackgroundIn recent years, a variety of short stems have been introduced. To date, mid- and long-term results of calcar-guided short-stem designs have been rarely available.Materials and methodsTwo hundred and sixteen calcar-guided short stems were included in combination with a cementless cup in a prospective study. Patients were allowed full weight-bearing on the first day postoperatively. Harris hip score (HHS) as well as pain and satisfaction on visual analogue scale (VAS) were assessed during a median follow-up of 61.7 months. Standardised radiographs were analysed at predefined time points regarding radiological alterations such as bone resorption and remodelling, radiolucency, osteolysis and cortical hypertrophy using modified Gruen zones.ResultsAt mid-term follow-up, no revision surgery of the stem had to be performed in the whole collective. At 5 years, HHS was 97.8 (SD 4.7), satisfaction on VAS was 9.7 (SD 0.7), rest pain on VAS was 0.1 (SD 0.5), and load pain on VAS was 0.6 (SD 1.2). Compared to the 2-year results, femoral bone resorption increased significantly at the 5-year follow-up (3.9% versus 42.3%). Rate of femoral cortical hypertrophy remained stable, occurring in a total of 9 hips (4.5%). At the 5-year follow-up, 2 stems (1.0%) showed non-progressive radiolucent lines with a maximum width of 2 mm. Signs of osteolysis were not observed. Compared to the 2-year follow-up, no further subsidence was observed.ConclusionsThe rate of stem revision (0%) at the mid-term follow-up was remarkable and indicates the principle of using a calcar-guided short stem as being a safe procedure. However, signs of bone-remodelling, indicating some amount of stress-shielding, must be acknowledged at 5 years depending on stem alignment and type of anchorage.Level of evidenceIV, Prospective observational studyTrial registration German Clinical Trials Register, DRKS00012634, 07/07/2017 (retrospectively registered)

Primary stability of calcar-guided short-stem total hip arthroplasty in the treatment of osteonecrosis of the femoral head: migration analysis using EBRA-FCA

“…To date, to our best knowledge, no analysis of the migration pattern of a new-generation short-stem design in patients with ONFH has been published, using a validated method like EBRA-FCA. The results of the present study showed similar outcomes compared to the previously published data in patients with osteoarthritis [ 7 , 10 , 21 , 34 ]. As it was found in patients with osteoarthritis, at mid-term no stem failure and revision occurred.…”

“…But it is still unknown if this prediction can be transferred to short-stem THA as well. Previous studies have performed migration analyses in short-stem THA following the indication of primary osteoarthritis using EBRA-FCA [ 7 , 21 , 34 ]. Kutzner et al [ 34 ] investigated the optimys stem in patients with primary and secondary osteoarthritis.…”

“…The design of calcar-guided stems, such as the optimys stem, differs to that of the early short stem designs with solely metaphyseal anchorage, such as the Metha stem. Whereas most varus hips achieve stabilization by three-point fixation in the metaphyseal bone, in calcar-guided short-stem THA, due to the design properties, some neutral and most valgus hips may also be stabilized by supplementing an additional fit-and-fill fixation in the proximal diaphysis [ 7 ] (Fig. 4 ).…”

“…This study aimed to investigate the migration pattern of a bone preserving and calcar-guided short-stem in patients with particularly the diagnosis of ONFH, using EBRA-FCA. The authors hypothesized that the investigated short-stem design can safely be used in patients with ONFH and that the migration pattern does not differ compared with the findings, previously published in patients with primary osteoarthritis [ 7 , 10 , 11 , 21 , 22 ].…”

Calcar-Guided Short Stems in Total Hip Arthroplasty: A Two-Year Prospective Multicentre Study

“…These THA related results were somewhat to be expected with regard to one of the most successful surgical procedures, if any. And our clinical results are in line with a study conducted by Kutzner et al [2].…”