Restoration of Some Anatomical Dimensions By Spiron Short Stem Hip Replacement Applied To Vietnamese People

Background: The process of using proximal bone in hip arthroplasty will allow the remaining bone to be preserved in future surgeries. To take advantage of these advantages, many types of short stem prosthetics have been developed in recent years. The obtained survey parameters combined with the obtained anatomical parameters shown that the Spiron joint is suitable when applied to adult Vietnamese. Research subjects and methods: The anatomical dimensions of the hip joint related to Spiron joint replacement were analyzed by the authors. Results: The anatomical results with Spiron showed that the acetabular average diameter and tilt angle were 49.77 mm and 41.55°. The femoral neck-to-body angle, the femoral upper-neck diameter, the distance from the crest to the hard shell along the femoral neck axis was on average 131.52°, 34, 32mm, and 51.39mm, respectively. The offset distance from the center of the crest to the axis of the femur is 38.33mm. These parameters show the working ability as well as stability when replaced by the Spiron joint. Conclusion: When applied to adult Vietnamese, the femoral neck diameter is consistent with the Spiron diameter. Preoperative planning is needed to check the femoral neck angle and femoral neck length prior to surgery to see if the Spiron joint replacement is eligible. The ndings of this study support the assumption that it is feasible to use Spiron prostheses in joint replacement in Vietnamese adults.


Introduction
Hip replacement is often used to treat degenerative joint diseases, aseptic necrosis of the femoral head, and ankylosing spondylitis in ankylosing spondylitis. In Vietnam, hip replacement is most common in Avascular necrosis (AVN) of the femoral head. This disease usually occurs in the 40-60 age group and more and more young patients need joint replacement. The number of young patients with aseptic necrosis of the femoral head in Vietnam is increasing day by day. This patient will have to face the second and the third time joint replacement after the rst time joint replacement [1][2][3].
When having to replace the joint for the second and third time, it will face a more di cult and complicated technique along with a much higher rate of complications and symptoms than the rst joint replacement. Since then, a number of short stem joints designed with the aim of preserving the bones of the neck and upper femur were born. Recently, Spiron short stems joints have been used a lot for young patients, however, studies on Spiron hip joints have only been limited to a short follow-up period and a small number of patients. The researchers all agree that the results need to be followed up for a longer time [4,5]. In general, studies show that the introduction of the short-stem hip joint in general and the Spiron hip, in particular, has overcome di culties and limit complications when replacing joints [6,7].
However, it also presents many disadvantages such as more di culty when reaming and placing the acetabulum due to retention of the femur neck or di culty in choosing the position when placing the mandrel exactly as desired.
When it comes to total hip arthroplasty (THA), the orthopedic community has seen a growing interest in more conservative surgical techniques for hip arthroplasty [8][9][10]. Meanwhile, second-generation hip resurfacing and minimally invasive surgery (MIS) have received widespread attention. After a period of application, both of these THA methods encounter worrisome problems. As the number of hip rehabilitation decreases, both patients and surgeons are looking for other potentially successful conservative treatments for THA. Recent studies have focused the surgeon's interest on short-stem replacement designs. Today, there are many types of short stem implants with little clari cation on the basis of design, xation, surgical technique, and clinical outcome [11,12]. Almost every major implant company now offers short stems and comes in a variety of designs. However, it is important to note that not all short stems achieve initial xation at the same bone interface region. Furthermore, surgical techniques vary widely, and the postoperative radiological interpretation of the position and xation of the short stem requires careful consideration [13,14]. Research by Thielen et al. [15] shows that the advantages of cement-free total hip arthroplasty are immobilization through bone growth and avoidance of problems associated with polymethyl methacrylate (PMMA). However, achieving the perfect position for bone restorations requires precise preparation of the pulp cavity with a variety of shafts of different shapes and sizes. Other problems noted with the use of cementless systems include fractures, bone resorption and excessive movement between the implant and bone. Important technical aspects of cementless total hip arthroplasty involve optimal t and ll, for the restoration to be stable, bone growth is promoted, and weight-bearing is transferred to the physiologically proximal femur.
In order to contribute to limiting the disadvantages and promoting the advantages of Spiron short joint, it is necessary to improve surgical techniques to restore hip anatomy after replacement. Therefore, it is necessary to study the anatomy of the hip joint to have an orientation to choose the appropriate joint size, position, and angle of the Spiron mandibular joint, thereby restoring the anatomical structure to maximize the function of the joint. Nowadays, there are only a few studies on the size of the femoral head alone, but none have studied the anatomical dimensions of the hip related to Spiron replacement, especially applied to other human races together. Stemming from the above reasons, in order to further improve the effectiveness of treatment, we carried out this work with the goal of determining some dimensions of hip anatomy for adult Vietnamese.

Hip Anatomical Parameters Related To Spiron Joint Replacement For Vietnamese People
The study was conducted on 129 normal hip X-ray lms of 83 Vietnamese adults aged 18-50. The study period was conducted from February 2012 to October 2016, at the Institute of Trauma and Orthopedics, 108 Vietnam Central Military Hospital. This process aims to nd the average value of the hip anatomical index representing the Vietnamese, the study sample size follows WHO guidelines and is determined by: where: n is the sample size, α is the coe cient of signi cance, Z is the con dence coe cient (Z = 1.96 with 95% con dence), p = 0.58 is the predicted proportion in the population, d = 0.09 is the absolute error.  (Fig. 2b). P is the midpoint of arc XC, Q is the midpoint of arc YD (Fig. 2c). The length of the superior border of the femoral neck: is the distance from point X to point C (Fig. 2a). The length of the lower border of the femoral neck: is the distance from the Y point to the D point (Fig. 2b). The upper and lower distance between the femoral neck (legacy neck): is the distance between the 2 points P and Q (Fig.   2c).

Study dimensions and measurement methods
Indicators related to the selection and placement of the Spiron mandibular mandrel include the distance from the base of the femoral head to the medial edge of the lateral femoral wall, the angle of the neck of the femoral body, the distance from the center of the crest to the anatomical axis of the femur (offset). The distance from the base of the femoral head (close to the femoral head) to the medial edge of the lateral femoral wall (along the median axis of the femoral neck) is the distance from point I to point K as shown in Fig To determine the size through the X-ray lm of the hip, the authors use the standard object as described in Fig. 4a, through the standard size will accurately determine the true size in the X-ray lm. The reference object is a ball 28 mm in diameter, mounted on a transparent plastic block through which it is easy to place the reference object in the desired positions. Before imaging, the reference object is placed midway and closest to the groin (so that the reference object is in the same plane as the femoral head, between and closest to the hip joints) as shown in Figs. 4c and d. The patient lies supine with legs extended, heels 20cm apart, feet internally rotated (for consistency and accuracy, all patients with both legs are xed on a wooden stand (20 cm wide base, the sidewall is tilted 20 degrees, upper is 2 thumbs tied as shown in Fig.   4b), this position allows the foot to rotate between 15º -20º), balanced hip distance, distance from the ball to the pubic joint is 100cm (Figs. 4c and d) The results obtained as described in Table 1     The results in table 8 show that the distance from the center of the crest to the femoral shaft (offset) is 38.33 mm. Thus, the results of our study are equivalent to those of Sanchita R. and Siwach R.C [9]. This is a size that has received little research attention, but it is very important in restoring hip function. Since the beginning of hip replacement surgery in the literature, there has been a lot of debate about whether to reduce or increase offset. In terms of biomechanics, there are both advantages and disadvantages when the offset changes. The advantage of increasing offset is that the extension of the swingarm reduces the load on the joints, reduces the risk of collision, and expands the free range of motion of the joint. The disadvantage of an increase in offset is an increased load on the distal end of the mandrel. Clinical features: Patient height, pain level, hip range of motion, walking ability, Harris score, complications such as nerve damage, infection, joint dislocation, deep vein thrombosis, etc. After measuring and calculating the necessary parameters for the surgical procedure, the expected mandibular placement according to the index calculated into the femoral neck (Fig. 6a). After selecting a suitable mandrel, re-determine the o cial femoral neck cut position by measuring the distance from the greater trochanter and the lesser trochanter to the plate (AC, BD lines - Fig. 6b), the AB line is the o cial femoral neck cut.
The model calculates the dimensions of the acetabulum diameter, the angle of the acetabulum as described in Figs. 7a and b. The angle of the femoral neck: before surgery (Fig. 8a), the angle between the mandibular axis and the anatomical axis of the femur after surgery (Fig. 8b). The distance from the end of the mandrel to the post-operative hard bone wall and the time of nal examination: Measured from the center of the plane of the end of the mandrel to the medial edge of the lateral wall of the femur along the mandibular axis (Fig. 8b).
Distance from the medial inferior ridge of the bilateral acetabulum (teardrop) to the line passing through the superior border of the trochanter and the limb deviation (mm) as shown in Fig. 9. Measuring the length of the lower extremities of the patients after surgery if the limb deviation is less than 5 mm, they are classi ed into the group of results where the legs are of equal length.
Studying a number of hip anatomical indices related to Spiron joint replacement helps to determine the measurement method and the range of this value from which to make a pre-operative plan on the computer (Fig. 6a). Through the analysis to determine the femoral neck cut position (Fig. 6b), the oscillometric distance of the femoral neck angle (concentrated in the range 125° -135° (73.6 %)), the distance from the center crest to the anatomical axis of the femur (27.1 -51.2mm), etc., to compare with the values measured during surgery. If the measured value is outside of this range, care should be taken to check that the measurement method is correct, the position of the Spiron mandrel is correct. This is a very important job to help improve the quality of treatment.
In fact, if the exact size of the hip handle cannot be predicted, when reaming the femoral neck or placing the shank larger than the actual size, the risk of femoral neck fracture is very high. With a standard hip shank, the upper femur bone is thick and hard to break, while in Spiron joint replacement, the femoral neck is thin and weak, so it is easier to break. If for fear of breaking the femoral neck, the joint handle is smaller than the actual size, then the joint is not pressed against the hard bone wall, the more spongy bone will quickly cause joint loosening. In short-handle hip replacement in general and Spiron hip replacement in particular, due to the retention of the femoral neck, the observation, reaming, and acetabular placement are often more di cult than in long stem hip replacement, so preoperative planning Using the computer to accurately predict the size of the acetabulum, the joint will help the surgeon to be proactive in this case.

Conclusion
The mean femoral neck-body angle was 131.52°, and the mean femoral upper-neck diameter was 34.32 mm. The average distance from the base of the crest to the hard shell along the femoral neck axis is 51.39 mm. The distance from the center of the crest to the axis of the femur (offset) is 38.33 mm.
The short stem hip replacement in general and Spiron hip replacement in particular, due to retention of the femoral neck, observation, reaming, and acetabular placement is often more di cult than standard hip replacements. So preoperative planning is required. Using the computer to accurately predict the size of the acetabulum, the joint will help the surgeon to be proactive in this case.

Declarations
The data in the manuscript was created by the authors Ethics approval and consent to participate The study has been approved by the Ethical Committee in Biomedical Research, 108 Military Central Hospital, Hanoi, Vietnam (No. 225/QD-V108). All patients in the study were asked for their consent, and they agreed to participate in the study. They were noti ed of their complete right to withdraw from the study at any time without threats or disadvantages.

Consent to Participate
Consent to Participate was obtained from all individual participants included in the study.

Consent to Publish
Consent to Publish was obtained from all individual participants included in the study.

Con ict of Interest
The authors declare that they have no con ict of interest.   Preoperative planning on radiographs and formal femoral neckline determination  Distance from the center of the crest to the anatomical axis of the femur (offset) Figure 9 Distance from the inferior ridge in the acetabulum to the line passing through the superior border of the 2 minor trochanters and limb deviation