Materials
In the Moscow City Arthroplasty Center of Botkin City Hospital and Sechenov University during the period from 2012 to 2018, a total of 103 THAs were performed in 93 patients. The maximum follow-up period was 84 months, and the minimum follow-up period was 15 months. The mean follow-up duration was 4 years (49.5 ± 11.7 months). The distribution of patients by the number of previously performed operations in different years (during the period from 2012 to 2018), ages, and diagnoses is presented in Table 1.
Table 1
Distribution of patients by year and number of surgical interventions performed according to the preoperative diagnosis.
Year | Number of patients | Number of interventions | Age (years) | Sex | Diagnosis/number of surgeries |
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FF | MМ | FHAN | Unilateral idiopathic coxarthrosis | Bilateral idiopathic coxarthrosis | Dysplastic unilateral coxarthrosis | Femoral neck pseudarthrosis |
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2012 | 113 | 15 | 40.2 ±5.7 | 66 | 99 | F-2 M-2 Total 4 | F-3 M-5 Total 8 | F-1 M-0 Total 1 | 0 | 0 |
2013 | 111 | 11 | 43.3 ±2.1 | 55 | 66 | F-0 M-4 Total 4 | F-3 M-3 Total 6 | 0 | F-1 M-0 Total 1 | 0 |
2014 | 111 | 13 | 39.1 ±8.7 | 44 | 55 | F-4 M-0 Total 4 | F-2 M-5 Total 7 | F-1 M-1 Total 2 | 0 | 0 |
2015 | 113 | 15 | 42.9 ±7.6 | 66 | 77 | F-3 M-1 Total 4 | F-0 M-5 Total 5 | F-1 M-2 Total 3 | F-1 M-0 Total 1 | 0 |
2016 | 118 | 19 | 40.8 ±5.3 | 55 | 113 | F-0 M-2 Total 2 | F-1 M-9 Total 10 | F-0 M-1 Total 1 | F-2 M-2 Total 4 | F-0 M-1 Total 1 |
2017 | 118 | 20 | 48.1 ±2.1 | 55 | 113 | 0 | F-2 M-12 Total 14 | F-1 M-2 Total 3 | F-0 M-1 Total 1 | 0 |
2018 | 99 | 10 | 39.8 ±9.1 | 44 | 55 | 0 | F-0 M-5 Total 5 | F-1 M-0 Total 1 | 0 | 0 |
Total | 993 | 103 | 46.7 ±12.1 | 335 | 558 | 18 surgeries | 55 surgeries | 22 surgeries | 7 surgeries | 1 surgery |
The large variation in the number of interventions in different years is explained not only by economic issues but also by the difficulty of choosing active people of working age from a cohort of elderly patients. Thirty-five women and 58 men aged 19 to 64 years were surgically treated. The number of treated women in the study was 1.6 times less than that of men. Women of childbearing age (19 to 40 years) predominated, and these individuals also had a high degree of physical activity, which was a determining factor for choosing the CoC friction pair.
Sixty-four patients (68%) experienced idiopathic coxarthrosis. These patients were of fairly young working age (31 to 64 years; average 46 years) and had previously engaged in amateur and professional sports. Of these, 50 (53.8%) were men and 16 (17.2%) were women. In the entire studied population, bilateral THA was performed in 11 patients (11.9%) experiencing bilateral destruction of the hip joints. Of these, 6 were men (54.5%) and 5 were women (45.5%). A total of 18 cases of femoral head aseptic necrosis (FHAN) were registered in our patient population. The sex distribution of those with FHAN was equal. Seven THAs for dysplastic coxarthrosis were performed in 4 women and 3 men. Only 1 patient (1.1%), aged 60 years, experienced femoral neck pseudoarthrosis, which was the outcome of previous incorrect osteosynthesis for femoral neck fracture. Three patients (women aged 49, 57 and 58 years) with bilateral destruction of the hip joints refused consent to required hip arthroplasty of the second joint.
When performing THA, we sought to maximize the use of large cups depending on a specific condition, and accordingly, we aimed to use large-diameter tribological pairs to prevent luxation by the implant itself. The use of a large-diameter friction pair reduces the risk of endoprosthesis luxation due to an increased distance that the femoral neck travels until impingement with the edge of the acetabular component [26], [3]. However, it is possible that a large-diameter tribological pair can produce various acoustic noises in the implanted prosthesis. Will it bother the patient? How will tribological pairs with different diameters behave in fairly young, previously active and healthy patients? Accordingly, for observation and evaluation of the results, all 103 THA cases were divided into working groups where different CoC diameters were used: 40 mm, 44 mm, and 48 mm. There were 2 exceptions: female patients of small stature, i.e., 149 and 152 cm, with BMIs of 13.2 and 14.8, respectively. The minimum size of the native acetabulum, even after preparation, allowed the implantation of a cup with a ceramic head of a maximum of only 36 mm. A more significant geometric parameter in such a situation is the difference between the diameter of the cup and the size of the endoprosthetic head. We believe that this situation is quite representative, and these 2 patients did not require separate allocation but were included in the group of patients with a 40-mm diameter ceramic head. The general characteristics of the patients are presented in Table 2.
The durations of surgical interventions were similar between groups. The longer intervention duration time in group 3 was due to the thickness of the subcutaneous adipose tissue in the trochanteric region and the time required for its suturing. The higher intraoperative blood loss in group 3 can be explained by the larger diameter of the acetabulum. In the postoperative period, standard drainage was established intraarticularly for 2 days to provide an active aspiration of discharge in 100% of patients. There was little difference in postoperative blood loss among the 3 groups. Intraoperative and postoperative blood loss in all groups analysed was not critical. Body mass index was comparable in all groups regardless of sex. The time intervals for monitoring patients after surgery were similar.
Table 2
General characteristics of patients with different Maxera Cup CoC diameters.
Parameter | Friction pair diameter, 40 mm | Friction pair diameter, 44 mm | Friction pair diameter, 48 mm |
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Total number of patients, 93 - Males, 58 (62.4%) - Females, 35 (37.6%) | Males, 13 (22.4%) Females, 11 (31.4%) | Males, 20 (34.5%) Females, 14 (40%) | Males, 25 (43.1%) Females, 10 (28.6%) |
Total number of interventions, 103 | 31 (30.1%) | 38 (36.9%) | 34 (33%) |
Patient age (years) Males Females | 41.9 (± 2.1) 28.7 (± 2.6) | 49.8 (± 6.6) 34.5 (± 8.7) | 50.8 (± 3.6) 32.8 (± 4.4) |
BMI | Males, 23.2 (± 5.4) Females, 20.6 (± 7.4) | Males, 24.1 (± 9.8) Females, 23.3 (± 6.7) | Males, 25.3 (± 7.6) Females, 21.8 (± 9.8) |
Intervention duration (min) | 83.4 (± 15.5) | 88.7 (± 14.7) | 91.1 (± 15.6) |
Intraoperative blood loss (ml) | 249.1 (± 86.7) | 292.1 (± 66.7) | 310.5 (± 74.3) |
Postoperative blood loss (ml) | 420.3 (± 110.6) | 439.9 (± 116.7) | 484.2 (± 112.4) |
Duration of follow-up (months) | 69.5 (± 6.5) | 71.5 (± 7.2) | 70.4 (± 4.1) |
All patients underwent a preoperative and postoperative clinical examination of the range of motion. The data obtained were recorded in the HHS protocol. In 100% of patients, prior to arthroplasty, impaired gait and claudication were noted. Eighty-one patients (87%) were able to ambulate only with additional support. Of these, 63 patients (77.8%) walked with a cane, and 18 patients (22.3%) walked with crutches. Seventy-four patients (79.6%) used railings for support when climbing stairs. Only 27 patients (29%) in the entire cohort could pass at a distance of 2–3 quarters. When wearing socks and shoes, 13 patients (14%) required outside aid. When moving around the city, only 36 patients (38.7%) used public transport, and the remaining patients preferred a car with a driver. Only 30 patients (32.3%) from the cohort of those who had a driver license could independently drive a car. The clinical preoperative examination showed fixed flexion contracture in 78 patients (83.9%) and fixed adduction in 62 patients (66.7%). More than 15 degrees of internal rotation during extension was registered in 2 cases (1.94%). A difference in the length of the lower limbs of more than 1 cm was registered in 73 patients (78.5%).
Methods
The monoblock Maxera Cup (Zimmer Biomet) acetabular system was used in all cases as the acetabular component with 4th -generation ceramic insert Biolox delta ceramics (CeramTec Gmbh). The Maxera Cup has large-diameter bearings for Biolox delta or Biolox option femoral heads and ranges in size from 36 to 48 mm. The cup is made of Tivanium titanium alloy of cementless fixation with an internal cone of 18 degrees and a fixed aluminium-zirconium ceramic insert (bearing). The full hemispherical cup design has three sets of paired anti-rotation ribs to ensure the stability of the press-fit fixation. The CoC friction pair provides increased wear resistance and high resistance to destruction, as well as chemical and hydrothermal stability.
Our choice of the Maxera Cup was obvious. It allows a larger diameter of the head to be achieved. The use of a cup with a factory-installed ceramic insert precludes the incorrect positioning of the insert and reduces the duration of the implantation procedure. There is no need to screw the screws into the cup, which also reduces intraoperative time.
We used a fourth-generation CoC friction pair in all 103 cases. A range of monoblock Maxera Cup sizes was used, where the choice was primarily dependent on the size of the patient’s acetabulum, the presence of acetabular cysts, a deficiency at the bone edge, the presence of osteophytes, and the intent to implant the cavity that can provide the largest friction pair size with an increased range of joint motion and anti-luxation function. The average size of the implanted endoprosthetic cup was 58 mm (range 48–64 cm).
At the preoperative planning stage, hip joint CT was performed in patients with dysplastic arthrosis, thus revealing the possibility of achieving full acetabular sphericity and acetabular depth when installing the Maxera Cup with minimal bone margin deficiency. Otherwise, the patient was excluded from the study cohort and excluded from the study. These clinical situations required other options for restoring and creating the supporting ability of the acetabulum (multiperforated cups, tantalum devices, reinforcing rings, bone grafting of the defect and others). The use of a Maxera Cup (Zimmer Biomet) in our study was 100%. We used different femoral components of the endoprosthesis (Zimmer Biomet), as presented in Table 3.
Table 3
Choice of implanted femoral components of the endoprosthesis.
Name of the endoprosthesis stem (Zimmer Biomet) | Clinical diagnosis | Number used (n = 103) |
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Fitmore Hip Stem | Idiopathic coxarthrosis, FHAN | 66 (64.1%) |
CLS Spotorno Stem | Idiopathic coxarthrosis, FHAN | 7 (6.8%) |
Wagner Cone Prothesis Hip Stem | Dysplastic coxarthrosis, proximal femoral dysplasia | 2 (1.9%) |
Avenir Hip Stem | Dysplastic coxarthrosis, FHAN, acetabular dysplasia | 17 (16.5%) |
M/L Taper Hip Prothesis | Idiopathic coxarthrosis, FHAN | 6 (5.9%) |
Alloclassic Zweymuller Stem | Idiopathic coxarthrosis, FHAN | 5 (4.8%) |
The choice of hip stem depended on the shape of the medullary canal, bone quality, proximal femoral dysplasia and femoral neck torsion. Considering the prevalence of young patients of working age, we preferred Fitmore proximal fixation stems (66 cases, 64.1%) not only to achieve osseointegration but also to maximally spare the patient’s own proximal femoral bone tissue. In 2 cases of acetabular dysplasia, the Avenir stem was implanted. In 2 cases of proximal femoral dysplasia with a version of the femoral neck, the Wagner conical stem was implanted to allow proper positioning of the endoprosthesis components. In this situation, a preoperative hip joint CT scan was performed. The achieved functional results were evaluated using the Harris Hip Score (HHS) scale, where the sum of 80–100 points indicated a good result, 70–79 points indicated a satisfactory result, and less than 70 points indicated an unsatisfactory result.
Thus, all 103 THAs in 93 patients were divided into 3 groups according to the diameters of the CoC friction pairs used (40, 44, and 48 mm). One hundred percent of the patients were available for examination. The patients were evaluated using the HHS before surgical intervention, at 3 months, 6 months, and 1 year after arthroplasty and subsequently at intervals of 1–3 years, 3–5 years, and 5–7 years, which allowed us to obtain mid-term results. An X-ray examination was performed before surgery (standard X-ray of the pelvis with two hip joints on one film, damaged hip joint in frontal view and in Lauenstein setup view) and at the time points described above. CT was performed in cases of joint dysplasia.
The data obtained in this study were processed using the statistical software Statistica 10.0 and IBM SPSS Statistics 22.0. We used the Kolmogorov-Smirnov test to statistically analyse the study results to determine the normality of data distribution. Normally distributed continuous variables are presented as the mean (M) ± standard deviation (SD). To describe qualitative characteristics, relative (%) and absolute values were used. Student’s t-test was used for the comparative analysis of quantitative parameters (parameters were studied before and after the operation). The chi-square test was used to compare qualitative characteristics.