Federal Scientific Clinical Center of Miners’ Health Protection, 

Leninsk-Kuznetsky, Russia

 

 During our analysis of the available specialized literature we have not found any estimation scales which could be used only for evaluation of outcomes of treatment for the acetabulum [13, 15, 19, 20]. It may be associated with the fact that many specialists do not give their attention to separation of the acetabulum into the individual segment, but they mean it as a part of the pelvis, although it is the second segment according to the AO classification [12, 17, 26]. Such approach cannot be reviewed as appropriate one, because of difference in the priority functions of the pelvic ring and the acetabulum (support and motion) [6, 23, 24, 27]. Among the existing estimation scales and systems (R. et J. Judet – 1952, Merle D’Aubigne and Postel –1954, M. Shepherd – 1954, M. Laransky – 1967, R.A. Goodwin – 1968, W.H. Harris – 1969, J. Charnley – 1972, B. Sterer – 1981, R. Johnston – 1990, M. Binkley – 1999) the greatest proportion provides either estimation after endoprosthetics or estimation before and after reconstructive surgery [15, 22, 25]. Therefore, according to our opinion, the greatest interest is associated not with the fact of joint replacement, but with the data about posttraumatic changes in the joints within the following years resulting in total joint replacement. That particular group of patients characterizes long term outcomes of treatment to the full degree [10, 16, 18, 21]. The opinions of the authors are contradictory in understanding the causes of posttraumatic complications including coxarthrosis and aseptic necrosis of the femoral head as judged by multiple literature sources. Some authors believe that perfect reposition (less than 1 mm of residual displacement) gives better long term results in comparison with unsatisfactory reposition (5 mm and over). If posttraumatic arthrosis appears, it develops significantly later and with slower progression than after unsatisfactory reposition. Other authors note that it is the situation when precision of joint reposition does not correlate with an outcome, which is defined by injury severity: the degree of destruction of anatomic structures and decompensation of joint perfusion. But, one way or another, the rate of unsatisfactory outcomes is high as before. Patients with posttraumatic coxarthrosis are 17-80 %, with ANFH after dislocation – 10-26 %. At prehospital stage the posttraumatic changes in the hip joint are identified in 60-90 % of patients; one-third of them requires endoprosthetics [2, 4, 5, 7, 11, 14, 21].

Objective – to investigate the determining factors of probability of development of degenerative changes in the hip joint as result of injuries to the acetabulum and the femoral head.

 

MATERIALS AND METHODS

In our study coxarthrosis and ANFH developed in 68 among 269 (25.3 %) patients with acetabular injuries according to the operating classification developed in Clinical Center of Miners’ Health Protection and based on the anatomic biomechanical principle of injury estimation [1, 8, 9]. The logic of construction of the classification is based on the following facts. The acetabulum is an incorrect hemisphere. Therefore, it is more reasonable to distribute it into the columns and walls, but not sectors [1, 3]. Moreover, their positioning is defined by the nature according to the sources forming the acetabulum (I – pubic – the smallest one, II – iliac – the biggest one, III – sciatic). The coxal bone goes through the ossification process by means of three main nuclei, which are meant for iliac, ischial and pubic bones. In the place of their fusion the acetabulum develops. The development of the acetabulum continues with the age, mainly by means of changing relation between its deepness and diameter (up to 0.60 in adults). The definition of the type of acetabular injury consists in citation of injured sectors in different combinations – I, II, III. The injury to all sectors is designated with IV. In the overwhelming number of cases the acetabular injuries are mediated and depend on the position of the femoral head (caput) at the moment of the injury and on its displacement after the injury. Therefore, we use the number of the sector (cap I, cap II, cap III). In case of dislocation of the head to the pelvic cavity (in central dislocation its position is designated as cap IV, and in normal centering in the acetabulum – cap 0). The fracture of the femoral head is designated as cap F (Lat. fractura). During classifying acetabular injuries we have found some particularities. According to our data, injuries to several sectors are observed in 72.6 %. In case of monosectoral injury to the acetabulum the highest proportion is associated with the injured regions in the sector III (17.4 %), followed by the sector II (7.8 %) and the sector I (2.2 %). Moreover, injuries in the first sector are often classified as stable injury to the pelvic ring (fractures of horizontal ramus of the pubic bone, fracture of the ischial bone). Dislocation of the femoral head towards different sectors was found in 54.9 %, and centering in the acetabulum was in 45.1 %. The highest amount of dislocations was found in the direction of the sector III (69.8 %).

Among 145 patients with different injuries to the femoral head 40 patients with primary endoprosthetics and lost contacts were excluded. The final subgroup included 83 patients with dislocations, fractures and dislocation-fractures of the femoral head. In such patients we could trace the long term results of treatment in different periods. In this group 41 patients (49.4 % among 83 patients) demonstrated destructive changes: with dislocation in 22 patients (26.5 %), fracture of the head in 11 (13.3 %) and fracture-dislocation in 8 patients (9.6 %). After recalculation for all patients who were treated in these nosologic groups (n = 105), except for the patients who received primary endoprosthetics, the relationship was as indicated below: the highest number of changes (56.4 %, 39 patients) was noted in dislocations, followed by fracture-dislocations (47 %, 17 patients) and fractures of the femoral head (22.4 %, 49 patients).

 

RESULTS AND DISCUSSION

The analysis of formation of the predictors was performed in the groups of the patients who were distributed according to the principle of a dominating injury: dislocation, fracture and fracture-dislocation of the femoral head.

1. The first group – the patients with dislocations of the femoral head. The risk of developing coxarthrosis is related to the following factors: the location of dislocation, time of reduction, treatment technique and presence of osteoporosis. The performed analysis showed that development of coxarthrosis was not influenced by such factors as osteoporosis and treatment technique (table 1).

Table 1
The patients with developed coxarthrosis in the group 1

Note: P > 0.05 with using χ² test

Time of reduction of dislocation and its location are the independent predictors of coxarthrosis non-correlating with each other. So, development of coxarthrosis is significantly related to location of the injury in the sector 3: 92.4 % in relation to 7.6 % without coxarthrosis. The relation was 50/50 % for location in the sector 2. As for the sector 1, the relationship is 30 % to 70 % (70 % in the patients without coxarthrosis).  The time factor was associated with coxarthrosis in case of dislocation reduction beyond 2 hours. In case of reduction of dislocation within 2 hours the probability of coxarthrosis was not higher than 10 %. Therefore, in location of dislocation in the sectors 1 and 2 the time of reduction was the determining factor (predictor) of the risk. In location in the sector 3 the time of reduction influenced (but not significantly) on the risk of coxarthrosis (table 2).

Table 2
Time of dislocation reduction in the patients in the group 1

Note: P < 0.05 with using χ² test

2. The second group included the patients with fractures of the femoral head. The following factors were important: location of the fracture, treatment technique and presence of osteoporosis. The degree of osteoporosis did not make any influence (table 3).

Table 3
The patients in the group 2 with developed coxarthrosis depending on degree of expressiveness of osteoporosis

Note: P > 0.05 with using χ² test

The factors influencing on developing coxarthrosis were: location of the fracture of the femoral head (superior or inferior hemisphere), method of treatment (conservative, surgical [osteosynthesis for the femoral head or removal of the fragment]). The distribution is presented in the tables 4-5.

Table 4
Dependence on location in relation to hemispheres in the group 2

Note: P < 0.00001 with using χ² test

Table 5

The patients in the group 2 with developed coxarthrosis depending on location in relation to hemispheres and treatment methods

*-statistically significant difference in coxarthrosis development for conservative technique and osteosynthesis for upper hemisphere.

** - statistically significant difference in coxarthrosis development depending on the technique in location in lower hemisphere.

After analyzing the results we could observe that in case of the injury to the superior hemisphere the possibility of developing degenerative processes was significantly higher and with statistical differences from the group with injuries to the inferior hemisphere regardless of the technique of treatment. Probably it is conditioned by the fact that the injury to the joint causes disarrangement in sealing (vacuum effect), congruence, stability, and the load does not demonstrate uniform distribution through the whole head. The parts of the superior hemisphere become more loaded that leads to rapid wear-out. Therefore, endoprosthetics is the method of choice for such injuries (if the patient’s state is appropriate). If injuries are situated in the inferior hemisphere the alternative variants are conservative technique and surgical removal of fragments of the femoral head. The possibility of complications is statistically lower for conservative treatment.                                                             

3. The third group included the patients with fracture-dislocations of the femoral head. The risk of coxarthrosis was associated with the following factors: location of fracture-dislocation, time of reduction, technique of treatment, osteoporosis (table 6).

Table 6
The patients in developed coxarthrosis in the group 3

None of the examined indicators influenced on development of coxarthrosis during the analysis! Apparently it is associated with significant destructions of bone- ligamentous structures that define further development of complications.

CONCLUSION     

Therefore, the predictor estimation of the results of treatment in the patients with acetabular injuries showed that the possibility of coxarthrosis increases with:

-         dislocation of the femoral head in the sector III,

-         uncorrected dislocation of the joint within 2 hours after injuries,

-         fractures of the femoral head in the superior hemisphere,

-         synthesized fractures of the femoral head in the inferior hemisphere,

-         fracture-dislocation of the femoral head as the most severe injury resulting in maximal possibility of coxarthrosis.