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Aim: The aim of this study was to evaluate the validity of Pauwels' classification of femoral neck fractures., Method: A study of literature was performed., Results: It has never been proven that the inclination of the fracture plane has a prognostic relevance. A number of papers prove the contrary, there are no publications where Pauwels' classification has been used successfully in selecting treatment modalities. Pauwels' theory of fracture inclination angle has not been transferred into clinical practice. This discrepancy probably goes back to the fact that the angle cannot be determined preoperatively, that in the majority of femoral neck fractures the angle is within the range of 40 to 60 degrees, that the theoretical angle variations do practically not exist, and that the shearing forces are reduced to an unknown amount by friction resistance due to the uneven fracture plane. The mechanical laws of the pseudarthrosis of the femoral neck cannot be extrapolated to acute fractures., Conclusion: The theory of Pauwels has apparently no clinical relevance for the majority of acute fractures, except for the rare transcervical fractures, and should not be considered any longer as a classification of acute femoral neck fractures due to the lack of prognostic and therapeutic relevance.

In a retrospective multicenter study we followed-up 30 fractures of the neck of the femur in children aged 11 years (1.5-15 years) for 4.8 years (0.5-20.0 years). It is the aim of this study to analyse factors possibly related to outcome, like age at injury, type of fracture, interval between injury and treatment, method of stabilization and postoperative interval until full weight bearing. At follow-up subjective parameters (pain, weather sensitiveness), clinical parameters (range of motion, claudication, leg length discrepancies) and radiological parameters (hip series) were investigated and medical charts and roentgenograms were reviewed using a standardized protocol. 29 of 30 children (96.7%) have sustained displaced fractures. Non-operative treatment has been applied in 4 children. 26 femoral neck fractures (type I: 1, type II: 8, type III: 17) were stabilized by internal fixation using screws and/or pins. Following non-operative treatment one child suffered a coxa vara and another child suffered a avascular femoral head necrosis in combination with coxa vara and leg length shortening of 4 cm. Following operative treatment 9 of 26 children (34.6%) suffered a avascular femoral head necrosis and 3 children (11.5%) suffered a coxa vara. In 6 of 26 children (23%) we observed leg length discrepancies > 2 cm. We were not able to demonstrate any significant follow-up result differencies between the groups of children who have sustained type II or type III fractures, or between the groups of children aged < 10 years when compared to children aged > 10 years, or between the group of children who were operated on within 6 hours after the accident when compared to the group of children operated > 6 hours after the accident. We observed no significant follow-up result differences between the groups of children who had different intervals between operation and full weight bearing. Operative fracture management remains the treatment of choice in the majority of displaced femoral neck fractures in children. However, in our limited study we were not able to demonstrate any significant follow-up result differences between the group of children treated by immediate open reduction and internal fixation (interval injury - operation < 6 hours) when compared to children who had been operated > 6 hours after the injury.

The lag screw osteosynthesis of medial femoral neck fractures is a straightforward procedure with little danger of complications. A conclusion may be drawn from the results of several authors that this method may even have a favourable influence in reducing the frequency of pseudarthrosis. In order to come to a final conclusion, however, the results of large treatment programmes would have to be studied. Fractures which are technically accurately treated allow probably full weight bearing. Lag screw osteosynthesis using more than 2 spongiosa screws in a parallel position has proved, both theoretically and practically, to be a useful method of treatment. The caudal screws increase the stability due to their position on the caudal rim of the femoral neck, while the cranial screws ensure against rotation and exertion of tensile force.

A correlation between the intra-articular pressure in the hip joint and blood flow in the femoral head has been demonstrated in both experimental and clinical data. A small effusion volume (2.5 cc) is capable of causing pathological pressure values, depending upon the position of the joints, although the highest volume capacity in the hip is well over 10 cc. Relief of post-traumatic tension hemarthrosis seems to be an essential therapeutic step, as it may prevent necrosis of the femoral head.

Valgus fractures of the femoral neck during growth are a rarity. Four cases are reported, and, in addition, one patient from the literature. Three were treated by bed rest, two by primary screw fixation. Clinical results were good; there was no necrosis. In accordance with the experience with similar fractures in adults primary osteosynthesis is recommended in all cases to prevent secondary displacement. Decompression of the hip joint by aspiration should be done for diagnosis and for decompression of tension haemarthrosis.

An experimental study was undertaken to evaluate the torque and axial force of the 6.5 mm ASIF lag screw implanted in the femoral neck after a subcapital osteotomy. The experiments were carried out on autopsied bones of more than 60 years of age. The average torque was 204 cmN, the screws in the upper half of the femoral head showing a higher torque than those in the lower half. The axial tension was measured by strain gauge transducer. Depending on the length of the thread of the screw (16 or 32 mm) the average tension reaches 1162 N or 1960 N. By tightening the screw until the impression of optimum fit is obtained, 70% of the maximum axial force is reached. It can therefore be estimated that at the beginning an interfragmentary pressure of 4000 to 8000 N is exerted on a medial femoral neck fracture fixed by four ASIF lag screws.