**3. Types of hemiarthroplasty**

#### **3.1 Based on prosthesis head component**

#### *3.1.1 Bipolar vs unipolar hemiartroplasty*

Hemiarthroplasty can be unipolar (the head is attached to the stem) or bipolar (in which there is an additional polyethylene bearing between the stem and the endoprosthetic head component). Previous systems, like the Moore, were unipolar arthroplasties with no modularity between the head and stem. Modularity is available in modern hip fracture arthroplasty systems for both unipolar and bipolar arthroplasties. In a bipolar arthroplasty, the second articulation ought to broaden the range of motion and reduce wear on the natural acetabulum, in principle. The production of particle wear debris as a result of the polyethylene might potentially result in osteolysis [15].

It is debatable that prosthesis should be used in hemiarthroplasty. Bipolar prosthesis is preferred by certain authors over unipolar prostheses by others. The motion at

### *Hemiarthroplasty DOI: http://dx.doi.org/10.5772/intechopen.106400*

the inner bearing of the bipolar prosthesis, in addition to the prosthesis-acetabulum interface, is its potential benefit. The quantity of acetabular erosion should be reduced as a result. According to radiological proof and clinically proven pain reduction, however, investigations have revealed that the bipolar prosthesis acts similarly to the unipolar prosthesis and that the inner bearing loses mobility with time. Additionally, the bipolar prosthesis' two- to five-fold higher price tag than that of the unipolar prosthesis raises the question of whether it has an impact on older patients' quality of life and functional outcomes following fractures with high death rates [16].

Less wear on the acetabular cartilage is a putative benefit of the bipolar design. This has led to the suggestion that it might be a better option for patients who are more active and have longer life expectancies. Although there is a chance that the stem will become looser, and synovitis will develop as a result of polyethylene wear on the inner surface of the bipolar head covered in polyethylene. Despite the fact that several RCTs have failed to produce conclusive results on differences in clinical outcomes between the unipolar and the bipolar designs, there are few studies that report on acetabular wear using a grading system [17].

The results of unipolar and bipolar hemiarthroplasty procedures following femoral neck fracture have also been shown to be indistinguishable in several recent prospective investigations. Parker et al. revealed no variations in mortality or complication rates between unipolar and bipolar hemiarthroplasty treatment in a recent evidence-based Cochrane study [16].

### **3.2 Based on prostesis assembly**

### *3.2.1 Monoblock vs modular*

Monoblock and modular prostheses are the two main types of prosthesis assembly that can be used in hip hemiarthroplasty. The diameter of the patient's femoral head affects the prosthesis size for a monoblock hemiarthroplasty. The most popular monoblock hemi-arthroplasty is the collared Thompson. These implants usually fail to correctly restore the patient's original hip geometry because of the pre-fabricated design of the prosthesis, which limits its ability to be modified intra-operatively to accommodate for variations in femoral neck offset or leg length [18].

The stem, neck, and head components of a modular hemiarthroplasty are all manufactured separately. The surgeon can modify component size while assembling these intra-operatively, allowing for a more accurate restoration of the patient's original hip.

### **3.3 Based on technique of femoral stem insertion**

### *3.3.1 Cemented vs uncemented hemiarthroplasty*

According to the method of implant fixation, hemiarthroplasty prosthesis can be divided into two different types: cemented and uncemented hemiarthroplasty. However, controversy still exists regarding whether cemented or uncemented implant fixation is preferable in this patient population [19].

During hip arthroplasty, fixation of the femoral stem can be accomplished with cement or via bony growth into a porous-coated implant [2].

Design-wise, hemiarthroplasty stems can be either cemented or uncemented, both of which have a track record of effectiveness. Comparable to the debate over cement- or cementless-prostheses in primary hip arthroplasty, the controversy over cemented or non-cemented hemiar-throplasty is similar. Although each has advantages and disadvantages of its own, it is not clear which is better. Uncemented stems, which operate using the press-ft approach, may offer advantages in terms of less invasive and shorter surgery time, but they also carry a risk of periprosthetic fractures and thigh discomfort from implant loosening because they perform poorly when it comes to osteointegration with osteoporotic bone [20]. Due to the quality of younger patient bone stock, cementless hip arthroplasties are generally considered to be more suitable for them [21].

There is insufficient evidence from randomized studies to declare one method of hemiarthroplasty to be better than the other in hip fracture surgery. According to some researchers, patients with cemented stems recover more quickly and with less discomfort than those who had non-cemented press fits [22] Primary cementless complete hip arthroplasties usually result in reports of mid-thigh discomfort.

Bone quality is crucial for non-cemented prostheses, in elderly people, it is typically subpar. Inability to create a congruent fit and interference with bone in-growth are two relative contraindications for non-cemented total hip prostheses, both of which prevent the formation of rigid initial stability [21].

The use of a cemented stem, on the other hand, results in better implant fixation because the cement improves the anchor-age, with fewer chances of loosening and thigh pain but higher risks of cardiovascular and respiratory problems because of cement-related toxicity and embolization of cement monomer, or "cement disease." [23]. Furthermore, in cemented situations, revision procedures become quite challenging [24].

Cement implantation has a well-established impact on the cardiopulmonary system, ranging from temporary hypotension and hypoxemia to abrupt mortality [25]. Uncertainty surrounds the pathogenic mechanism behind this. The majority of experts feel that it is a direct result of fat and marrow emboli [26]; other ideas include cement toxicity, reflex autonomic effects, prostaglandin-induced vasodilatation, and thromboplast in activating the clotting cascade, lowering platelet count and oxygen tension [27]. No of the underlying mechanism, the small cardiopulmonary alterations seem to be temporary and not clinically meaningful. The prevalence of unexpected intraoperative death appears to be less than (0.2%) [28].

In choosing between these techniques, there is limited evidence contrasting the functional outcomes, morbidity, and mortality with cemented or uncemented stems [29]. The cemented group has been shown to be associated with greater blood loss and operative time, the revision rate is lower, with significantly less thigh pain and better mobility [29]. In some investigation, the cemented prosthesis provided stable early fixation with good functional outcomes at 1-year follow-up [30].

There are no differences between using current cemented and uncemented hemiarthroplasty for the treatment of intracapsular hip fractures in terms of mortality risk. The frequency of intraoperative and periprosthetic fractures is much lower with modern cemented hemiarthroplasty, but anesthesia and surgical time are prolonged [31].
