The sampling frame consisted of 203 patients, 88% of whom who had undergone primary THA and 24% revision THA. Fifteen cases used HFPC-DMR-HA and 5 HFPC-DM-CEM acetabular cups and all twenty cases were included in the cohorts. Three (20%) and 2 patients (40%) were lost to 2-year follow-up, respectively (Fig. 2).
Sampling frame characteristics
Acetabular cups used in the sampling frame were 31 (15.3%) standard acetabular cups (STD) and 172 (84.7%) DM. DM were 15 (7.5%) HFPC-DMR-HA, 5 (2.5%) HFPC-DM-CEM and 152 (74.92%) other models (Figure 2). The overall female/male ratio was 107/96 (53%/47%) (Table 1) and DM were used in non-significantly different frequencies in the two genders (54.1%/45.9% Fisher exact test p = 0.436).
Mean age at the time of surgery was 69.1 [67.3, 70.9]. Patients treated with STD were significantly younger than patients treated with overall DM (mean difference 22.2 years [18.3, 26.1], p<0.0001). Patients with HFPC-DMR-HA were significantly older than patients with other DM cups (mean difference 5 years) (rank sum test: p = 0.0196).
All STD were used for primary THA. All revision THAs were performed with DM and represented 14% of DM use. Revision surgery accounted for 100% of HFPC-DM-CEM, 67% HFPC-DMR-HA and 6% of other DM cups.
Patients undergoing primary THA were younger than those undergoing revision THA (mean difference: 9.6 years [5.4, 13.8], p<0.0001).
The cohort median post-operative time to study follow-up date was 2.3 years (range: 1.7 ; 3.3) in HFPC-DMR-HA and 3.3 years (range: 1.7 ; 3.4) in HFPC-DM-CEM.
HFPC-DMR-HA cohort preoperative characteristics
Median patient age at the time of surgery was 85.6 years (range: 45.1 ; 93.3), female/male ratio was 60% / 40% and a median body mass index (BMI) of 24.6 kg.m− 2 (range: 14.5 ; 32.2) (Table 2). Revision THAs were due to loosening or fracture of the initial prosthesis (90%) and IPD (10%). Primary THAs were due to hip neck fracture or post-trauma necrosis (80%) and dysplasia (20%).
HFPC-DM-CEM cohort preoperative characteristics
Median patient age at the time of surgery was 78.8 years (range: 68.8 ; 86.9), female/male ratio was 60% / 40% and a median body mass index (BMI) of 25.8 kg.m− 2 (range: 22.8 ; 28.4) (Table 2). All cases (100%) were revision surgeries due to loosening or fracture of the initial prosthesis.
HFPC-DMR-HA cohort operative characteristics
All cases were performed with a posterior surgical approach. Acetabular shell diameters ranged from 44 mm to 64 mm. All shells were secured with two pegs and a screw and without cement and no bone grafting was reported. PE liners were fitted with mostly with ceramic femoral heads (87%) while the others were fitted with CoCr heads and a wide range of femoral stems were used (Table 2).
Median surgical time was 74minutes (range: 40 ; 120). No patient required bone grafting. Associated surgery was stem replacement in 27% of cases. One case required femoral cerclage wiring. All presented excellent intraoperative stability.
HFPC-DM-CEM cohort operative characteristics
All cases were performed with a posterior surgical approach. Acetabular shell diameters ranged from 46 mm to 52 mm. All shells were cemented without pegs or screws and one case (20%) required autogenic bone grafting. PE liners were fitted with mostly with ceramic femoral heads (80%) while the others were fitted with CoCr heads and a wide range of femoral stems were used (Table 2).
Median surgical time was 87minutes (range: 45 ; 120). Bone graft was required in one HFPC-DM-CEM. Associated surgery was stem replacement in 60% of cases. One case required femoral cerclage wiring. All but one presented excellent intraoperative stability.
Primary endpoint: Implant survival
One patient with HFPC-DMR-HA required revision surgery at 3 month follow-up related to a surgical site infection. No other revision or death occurred throughout follow-up. Implant survival was 94.7% [68.1; 99.2%] with a total time at risk of 31.3 years (Fig. 3).
No HFPC-DM-CEM required revision surgery and no patient death occurred at two year follow-up, implant survival was 100% with a total time at risk of 1.6 years.
Secondary endpoints: Postoperative implant or procedure-related complications
With HFPC-DMR-HA, 10 adverse events were reported in 9 (60%) patients, including 1 IPD (6.7%) at 1-year follow-up (Table 2). The most frequent adverse events were 3 deaths (20%) unrelated to the procedure and implant as well as 2 surgical site infections (13.3%) There was also 1 fracture of the operated area (Vancouver class A) after the patient fell at 2-year follow-up but no prosthetic revision was required.[11–12]
In patients with HFPC-DM-CEM, no post-operative adverse event was reported.
Secondary endpoints: Functional outcomes
In patients with HFPC-DMR-HA, mean within-patient HHS increased from preoperative baseline to 1-year follow-up by 44.9 [29.6, 60.3] (Wilcoxon signed-rank test p < 0.003) and mean within-patient mHHS increased from baseline to 1-year follow-up by 48.1 [33.9, 62.4] (p < 0.002) and from baseline to 2-year follow-up by 54.2 [36.2, 72.3] (p < 0.008).
In patients with HFPC-DM-CEM, mean within-patient HHS increased from preoperative baseline to 1-year follow-up by 27.7 [-11.1, 66.6] and mean within-patient mHHS increased from baseline to 1-year follow-up by 27.2 [-11.9, 66.3] and from baseline to 2-year follow-up by 45.3 [15.3, 75.4] but the small amount of data at follow-up prevented drawing statistical conclusions.
Pre- and postoperative HHS and mHHS summary in Table 3