Low Risk of Fracture Using a Cementless Triple-tapered Collared Femoral Stem with Automated Impaction in Direct Anterior Approach Total Hip Arthroplasty

Outcomes of 1,021 consecutive cases utilizing a triple tapered collared stem and automated broaching system

Background: For total hip arthroplasty (THA), a number of different femoral stem designs exist, each offering potential benefits and risks to patients. Preparation and implantation of the femoral component may be performed with manual instrumentation or with automated broaching systems. The combination of stem and femoral preparation choice may influence patient outcomes. The purpose of this study was to report on a large consecutive series of a collared, triple tapered, cementless stem broached and impacted with an automated system through a mini-posterior approach. Methods: 1021 consecutive THAs with a cementless triple-tapered fully coated titanium femoral stem performed by a single surgeon via a minimally invasive posterior approach all utilizing automated broaching (AB) were collected retrospectively. Patient demographic data, proximal femoral anatomical features, radiographic outcomes (e.g., subsidence), PROMIS scores, and intra-operative and postoperative complications were collected and analyzed. Results: 7/1021 (0.68%) intra-operative calcar fractures and 11/1021 (1.08%) postoperative periprosthetic femoral fractures were observed. The average postoperative subsidence was 0.5 mm. Subsidence was not associated with age, BMI, or proximal femoral anatomy (Dorr C). There were no revisions for postoperative mechanical loosening or instability. No increase in periprosthetic fracture was noted amongst the first 100 cases using AB (0/100) when compared to the subsequent 100 (0/100). All patients experienced statistically significant improvement in PROMIS scores postoperatively at 1-year follow-up. Conclusion: This large, consecutive, single surgeon series demonstrates excellent results of the aforementioned stem prepared and impacted with AB. At mid-term follow-up, there were no revisions for mechanical loosening and all-cause survivorship was 98.2%.

Preventing Periprosthetic Femur Fractures in Anterior-Based Approaches

Anterior approaches including the direct anterior and anterior-based muscle sparing approaches have grown in popularity for total hip arthroplasty. Despite many benefits, some studies have demonstrated an increased risk of periprosthetic fracture. Preoperatively, patient selection, careful templating, and strategic implant choice may decrease fracture risk. Recently, cemented stems and modern tapered, collared uncemented stems have been associated with lower fracture rates as well. Using careful surgical techniques, obtaining adequate exposure through sequential releases, and understanding various broaching strategies can all play a role in decreasing periprosthetic facture through anterior approaches to total hip arthroplasty.

Use of an Automated Surgical Impactor Reduces Femoral Broaching Time in Direct Anterior Approach Total Hip Arthroplasty: Results From a Randomized, Multicenter Study

Background

Impaction in total hip arthroplasty has typically been conducted using a mallet. A surgical automated impactor has been developed with the goal of reducing surgeon variability, fatigue, and injury. There is also potential to reduce the variability of each impaction step in which automated impaction is used, through reproducible and consistent application of force.

Methods

Patients were randomized into either the mallet control group, or the automated impaction study group (1:1 randomization). The primary endpoint analysis was conducted to demonstrate that femoral broaching time (in minutes) with an automated impactor is noninferior to femoral broaching time with manual instruments (mallet) under a noninferiority (NI) margin of 1.25 minutes, with a subsequent test of superiority. A total of 218 patients were randomized and treated (109 in each group).

Results

Mean femoral broaching time was 5.8 minutes in the automated impaction study group (automated), and 8.1 minutes in the mallet control group (mallet), a 28.4% reduction (P = .0005). However, there was not a difference in surgery duration between the groups. Three fractures were reported in the mallet group and 1 in the automated group.

Conclusions

In this randomized multicenter study, an automated impactor was shown to reduce femoral broaching time in primary total hip arthroplasty, with no increase in fractures, but no decrease in operating room time was noted.