5.1. Patient-Related Factors
The relationship between age and the occurrence of osteosynthesis failure remains controversial. Several authors found no correlation between these two variables
[7]
[8]
. In our study, no association was found between age and mechanical complications.
Women appear more exposed to proximal femur fractures. Bone loss accelerates in women immediately after menopause, increasing the risk of fractures related to calcium-phosphorus metabolism disorders. SHANG-WEN
[9]
identified female sex as a statistically significant predictive factor for screw cut-out (p = 0.001).
In our study, no correlation was found between consultation delay and osteosynthesis failure. Medical literature does not seem to address the correlation between a patient’s pre-fracture autonomy and mechanical failures. According to Langlais
[10]
, patient autonomy is an important factor in postoperative outcomes. In our study, a statistically significant link was found between pre-fracture autonomy and the occurrence of mechanical complications (p = 0.009). However, a study with a larger number of patients may be necessary to confirm this association (47 patients were excluded from our study. This could bias the results).
5.2. Fracture-Related Factors
Some authors, like MORVAN
[6]
and BARRIOS
[11]
, consider osteoporosis a risk factor for osteosynthesis failure. The risk of screw cut-out increases with the degree of osteoporosis. The more severe the osteoporosis, the less tolerant the implant is to poor positioning. The risk of osteosynthesis failure may depend on the degree of osteoporosis as assessed by Singh’s index. Conversely, others such as NORDIN
[12]
found no correlation between osteoporosis and therapeutic failure. In our study, we also found no such association.
Mechanical complications occur both after osteosynthesis of fractures in the trochanteric region and those in the femoral neck. In his study, REINA
[13]
reported 2 cases (4%) of mechanical complications in femoral neck fractures. PARKER
[14]
and SIKAND
[15]
reported similar complication rates. In our series, most failures were seen after osteosynthesis of trochanteric fractures, but no significant correlation was found.
5.3. Surgical Technique-Related Factors
In our study, the time between hospital admission and surgery was not identified as a predictor of failure. However, most mechanical failures (7 cases) occurred in patients operated on more than 96 hours after trauma.
The quality of fracture reduction was assessed using the criteria of BAUMGARTNER
[5]
[6]
. The literature shows disagreement about the correlation between fracture reduction quality and the risk of mechanical failure. Some authors
[7]
[16]
[17]
believe that poor reduction increases the risk of implant failure. Others, such as KASHIGAR
[18]
and GELLER
[19]
, found no statistically significant relationship.
MORVAN
[6]
observed that only 1 osteosynthesis out of 112 failed when the reduction was considered good, while over 12% of poorly reduced fractures experienced failure. However, this result should be interpreted cautiously. Poor reduction combines two criteria: interfragmentary displacement greater than 4 mm (often due to complex fractures) and a varus cervico-diaphyseal angle.
In our study, 3 failures were recorded in patients (n = 7) with poor reductions, but the association was not statistically significant (p = 0.2).
Most authors agree that TAD is a major predictive factor for osteosynthesis failure. A TAD > 25 mm significantly increases the risk of failure
[5]
[6]
[20]
, whereas a TAD < 25 mm reduces it. It is currently the only statistically proven mechanical failure predictor for DHS fixation .
However, in our study, a TAD < 20 mm was also associated with increased risk of screw migration into the hip joint (p = 0.023), which is highly significant. A small TAD could be associated with intra-articular migration of the screw, especially in elderly osteoporotic subjects. Therefore, a normal TAD should be between 20 and 25 mm. A study with a larger cohort would be needed to confirm this assertion.
Coviello et al.
[21]
have proven that the findings suggest that if reduction parameters are adequately achieved, an increase in TAD cutoff does not appear to influence the risk of implant failure.
According to several authors, the optimal frontal screw position is the middle or inferior third of the femoral neck (PRM between 0 - 0.66)
[5]
[6]
[9]
[20]
. In our study, the best positions were central or inferior. A superior screw position was associated with osteosynthesis failure in one of two patients.
As for the lateral view, PRM also defines screw position. Several authors
[6]
[8]
[18]
agree that the ideal lateral position is the middle third (PRM 0.34 - 0.66). Screws placed near the margins of the femoral head are more likely to fail, as noted by HSUEH
[16]
. Our results align with those found in the literature.
Recent studies have shown that the DHS plate screw still gives good anatomical and functional results
[22]
.