Modular Stems in Revision Hip Arthroplasty: A Three-Step Technique

Abstract

Background: Complications such as periprosthetic fractures necessitate challenging revision surgeries. In particular, femoral stem revisions can be complicated by poor bone quality, making primary stability and leg length restoration difficult to achieve. Modular fluted tapered stems (MFTSs) have emerged as a viable option for these complex cases. This study aims to describe a reproducible three-step technique for femoral stem revision using MFTSs. The technique focuses on (1) obtaining distal primary stability, (2) restoring leg length, and (3) ensuring overall implant stability. Materials and methods: We conducted a retrospective analysis of ten patients who underwent revision THA using this three-step technique, with a minimum follow-up of 12 months. The mean patient age was 70.7 years, and the average follow-up was 24.2 months. Limits were the small sample size, the lack of clinical outcomes and the short-term follow-up. Results: There was no subsidence, a mean leg length discrepancy of 4 mm (p: 0.604), and no dislocations. However, heterotopic ossifications (HOs) were observed in 25% of patients, although no trochanteric migrations occurred. One patient experienced an intraoperative femoral fracture, which was successfully treated. Conclusions: This three-step approach can break down the revision procedure, making it more accessible to surgeons. The findings suggest that this technique is effective in achieving reliable outcomes in femoral stem revisions, potentially improving the standard of care for patients requiring complex THA revisions.

1. Introduction

Total hip arthroplasty (THA) has become a standard procedure that is performed worldwide; the increasing number of procedures has led to a comprehensible increasing number of complications and failures. According to the data of the Swedish National Hip Arthroplasty Register reported in 2023, periprosthetic fractures represented the third most common cause of THA revision with 9.5%. The second and first reasons reported were dislocation and aseptic loosening with 13.1% and 60.1%, respectively [1,2,3]. Other studies reported the incidence of postoperative periprosthetic femoral fractures after primary arthroplasty as 0.4–1.1%, rising to 2.1–24% after revision surgery, with a cumulative risk over 15 years of 1–4% [3,4]. Another recent registry study from the UK reported a cumulative probability within 10 years of 1% [4]. These discrepancies among different registries appear to be due to different usages of cemented stems. The widely recognized classification for periprosthetic fractures after THA is the Vancouver classification introduced by Duncan in 1995. This classification not only considers fracture position but also bone quality and stem loosening [5]. In 2020, Stoeffel et al. enriched this classification with clinical, radiographical and intraoperative findings in order to build an algorithmic approach to periprosthetic fractures [6]. Vancouver B2 and B3 typically necessitate stem replacements; these implants can be either cemented or cementless [7,8]. Often, in periprosthetic fractures, or generally in femoral stem revision, metaphyseal bone stock can be reduced or of poor quality and the surgeons are challenged to achieve the best primary stability of the implant that is possible, appropriate leg length variations and a low dislocation risk. Wagner proposed the distal fit, fluted, mono-block tapered stem in the late 1980s [9]. Years later, different companies start to produce and commercialize new designs with the introduction of modularity to properly fine-tune leg length discrepancies and hip stability [10,11]. Higher rates of non-union fractures and residual bone defects have been reported in the literature by using cemented stems instead of cementless options [7,12,13]. Midterm clinical outcomes recently reported in the literature appeared to be in favor of cementless stems when compared with cemented ones despite their higher complication rate [14]. Periprosthetic fractures are among the most common causes of failures and have been widely described by a large number of authors. This complication can be addressed by reduction and fixation, but more commonly an implant revision of the stem or of the acetabular component is needed. Modular revision stems became a valid option in stem revision during the last several years, especially in cases of reduced bone stock [15]. Revision surgery can appear to be difficult and challenging but, in this case, it can be optimized, identifying different steps that are reproducible and effective despite the complexity of the case. Despite this, this technique is widely used and has been described with outcomes up to three years [16]; to our knowledge, there is no other paper that describes this procedure by dividing it into steps in order to make it a reproducible procedure to manage stem revision in r-THA. The aim of this study is to describe a one-stage revision procedure of femoral stems in three steps which can be performed successfully even by operating surgeons with limited experience following an appropriate learning curve.

1.1. Surgical Technique

The technique is recommended for periprosthetic femoral fractures or revisions requiring extended trochanteric osteotomies. A thorough investigation of the case is recommended; in our experience, a CT scan is recommended to understand the extension of the lesion or deformities leading to problems in surgery planning. Periprosthetic joint infection has to be ruled out before surgery. An image intensifier can be needed and has to be available in order to manage intraoperative complications and fractures. The patient is prepped and draped and the approach to the femur is the one the surgeon prefers most. Our cases have all been approached with a posterolateral incision. The incision then has to be extended at least 5 cm distally to the fracture. The bone is then fully exposed through a subvastus approach and the bone fragment has to be clearly identified, cleaned by hematoma and safely protected with retractors. Capsulotomy is then performed by a transfemoral approach and the acetabular component can be tested for stability and integrity.

The femoral bone distal to the fracture is exposed and a prophylactic cerclage wire is passed and secured 2 cm distally on the intact femur. A high tension is recommended on this cerclage because it has to be reliable in distraction to prevent the propagation of the fracture and mimic the isthmus in distal fractures. We recommend measuring the length of the fracture from the cerclage to the tip of the trochanter after a rough reduction in order to have a reproducible measure during the entire surgery. The femoral canal is then prepared, reaming progressively, starting with a small size ream to center the major axis of the canal. The correct medullary reamer size is reached when the contact of the instrument on the bone is large and a good torque is obtained. In this part, bone must be carefully managed in order to avoid intraoperative cracks. The length of the fracture from the cerclage has to be checked at this point and the proximal measure has to stop in an intermediate measure; this is dependent on the instrumentation utilized. If the measure is bigger, a smaller ream has to be prepared; conversely, if the measure is smaller, a larger one has to be used. The distal definitive stem is now implanted after checking the integrity of the distal cerclage (Figure 1). The authors’ favorite technique is to oversize the distal body of 1 size to obtain a better stability.

The distal stem is now implanted and in this second step the length of the limb has to be restored. Bearing in mind the measure of the proximal fragment, the proximal trial body is chosen and implanted. Length is assessed by reducing the implant and roughly closing the fracture fragments on the provisional construct. The correct size is checked using the contralateral lower limb and palpating the tension on the gluteus medius and vastus lateralis tendons. If the measure is intermediate between two different sizes of the proximal body, the fine-tuning can be performed using different head sizes. Once the correct length of the limb is achieved, the proximal body is provisionally closed (Figure 2). and the third step can be addressed.

The stability is checked in all directions of the hip’s range of motion without reducing the fracture. The authors recommend achieving the best stability by avoiding muscle tension but checking impingements very carefully. In this phase, the anteversion and offset of the proximal body has to be tested and decided. The position of the trial construct has to be carefully checked and registered. The proximal part of the femur is now prepared and reamed with the proper instrumentation in order to allow a better anatomical proximal body housing; the definitive proximal body is now implanted in the same position that was tested the trial (Figure 3). In this case, the metaphyseal portion must be carefully managed in order to avoid the fractures’ propagation and trochanteric disruption. The proximal femoral bone is now wrapped around the stem, reducing the fracture, and using two to three cables, if the greater trochanter is intact and the tendons’ insertions are preserved, a plate is not useful (Figure 4 and Figure 5). Impingement and stability have to be checked again after reduction. The three steps are resumed in

Table 1. Description of the three steps.

Step	Goal	Key
1	Distal primary stability	Diaphyseal preparation to obtain distal stem stability to build on.
2	Leg length restoration	Trail proximal body selection and insertion to avoid leg length discrepancies.
3	Anteversion and offset fixation	Fixing the neck anteversion and offset selection to obtain a stable hip.
3A	Reduction and fixation	Metaphyseal trochanteric bone should be reduced and fixed after stem implantation with another stability evaluation to avoid impingements.

.

1.2. Postoperative Management

Surgical drainage has been used in all patients. Full weight bearing is allowed after the first postoperative day. Passive and active motion of the hip is encouraged from the first day. Heterotopic Ossification (HO) prophylaxis is not compulsory but can be considered according to surgeon’s findings and the soft tissue damage, since this evidence suggests that revision surgeries present higher risks of HO development [17].

2. Materials and Methods

A retrospective analysis has been performed. Patients included underwent surgery between January 2022 and November 2024. Procedures were performed in a high volume center for replacement surgeries. The study received ethical committee approval. Inclusion criteria were a minimum of 12 months of follow-up, and the implantation of a modular stem in revision hip arthroplasty for non-oncologic reasons with a three-step technique. Implants utilized in all cases were Arcos modular femoral revision systems (Zimmer Biomet, Warsaw, IN, USA). Patients selected were 18 years old. Once inclusions criteria were applied, 10 patients were evaluated in our final analysis. Six patients were excluded because they were lost to follow-up, while the remaining two patients died due to not-orthopedics-related reasons. The mean age at the time of surgery was 70.7 years old (ranging from 80 to 39 years old). The mean follow-up was 24.2 months (ranging from 34 to 12 months). Patients included had surgery in two cases for aseptic loosening, in seven cases because of periprosthetic fractures and one patient had surgery for nail failure (

Table 2. Numbers and percentages of reasons for revision among the included patients.

Reason for Revision:
Aseptic loosening	2/10 (20%)
Periprosthetic fractures	7/10 (70%)
Nail failure	1/10 (10%)

). Radiographic and clinical follow-up was performed at 2 months and 1 year postoperatively. A Student t-test was performed to obtain the confidence interval.

3. Results

The subsidence rate reported at a mean FUP of 1 year was 0%. Leg length discrepancies were evaluated, and the mean discrepancy was 3.7 mm (p: 0.604; CI −5.36 mm to +3.36 m). No dislocation occurred among the evaluated patients (dislocation rate 0%). One year X-rays reported 25% Heterotopic ossification (HO) development, with four patients showing Brooker II in three cases and one showing Brooker I [18]. No trochanteric migrations were seen in 1 year and no gluteus insufficiencies were founded. One case (10%) reported an intraoperative femoral fracture below the stem. This intraoperative complication happened after the nail removal, and the weakness of the diaphyseal cortical due to the remaining holes from the distal screws can justify this complication during distal preparation and/or implantation. This complication has been treated with a reduction and osteosynthesis using a plate.

4. Discussion

Femoral revision surgery is growing in number and complexity; every hip surgeon has to be aware of this and will have to manage this problem in future. Historically, the most common warning about modular stems includes junction failures and femoral stem fractures; data collected from national registries presented revision rates due to stem fractures as between 0.4 and 0.5%. Moreover, modular stem compared with primary implants presented lower rates of revisions after stem failures [19].

The use of modular stems has simplified the procedure and made it more reproducible; this is a warranty for better and more consistent results, even in less experienced hands.

We describe our workflow for the procedure that divides a complex surgery into a three-step approach in order to provide a learning option for surgeons approaching this procedure. Our limitations are a small sample size, a lack of clinical outcomes, a short follow-up and high variability in reasons for revision.

A recent article and review of the literature by Schreiner et al. about the treatment of periprosthetic Vancouver B2 and B3 with modular uncemented stems reported encouraging results [20]. Their study included eighteen patients with a minimum follow-up of 18 months. The Mean Harris Hip score reported was 72.5, and the fracture healing rate was 94.4%. The trochanteric migration reported in their cohort was 38.9%. Complications described were PJIs in two cases, with an 11.1% total occurrence in the above mentioned cohort, one case of hip instability and two cases of wound healing disorders. They did not report any femoral shaft fractures during the procedures. Our cohort reported 0% trochanteric migrations using cables. Moreover, a recent review reported 5% non-union rates using cables for trochanteric fixation [21]. Satisfying results have also been described with a distally locked revision stem with an additional extended trochanteric osteotomy performed; their reported fracture healing rates were 95.8% [22]. Fink et al. analyzed these implants and their outcomes in Vancouver B1 periprosthetic fractures. In their study, the Harris Hip score improved from 22.2 preoperatively to 81.5 postoperatively. In radiological evaluation, no subsidence was seen and bony ingrowth occurred in all the included hips [23]. A recent review by Koutalos et al. [24] recorded results among the literature about modular and mono-block stems. Their results showed better radiological outcomes in terms of subsidence in modular stems compared with non-modular stems, despite a higher rate of intraoperative periprosthetic fractures. Nonetheless, there is significant variability among the modern designs of modular stems regarding geometry and stem taper angle; this could affect the rates of intraoperative fractures and the results reported in the literature. Clinical results collected in the aforementioned review showed similar Harris Hip scores (HHSs) when modular and mono-block stems are compared [25]. This evidence has been confirmed in a study conducted by Huang et al. [26]. Dividing a complex procedure composed of several steps into three well-stated and organized steps can lead surgeons to approach these surgeries with a schematized work flow, helping them obtain satisfactory results.

The results are encouraging in the literature [27,28,29] and in our practice in terms of clinical results and survivorship.

5. Conclusions

In conclusion, femoral stem revision surgery, particularly for periprosthetic fractures, presents a complex challenge that requires a methodical approach. These are the preliminary findings of an easy and reproducible approach to a challenging procedure even in cases with poor bone stock or significant deformities.

This type of surgery is usually reserved for experienced surgeons. This paper aims to break down the procedure as much as possible to help surgeons approach it with good reproducibility of results. However, future studies that include broader patient samples and are enriched with clinical outcomes are needed to definitively propose this technique as the standard for these cases.