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Neck fracture of a cementless forged titanium alloy femoral stem following total hip arthroplasty: a case report and review of the literature.

Grivas TB, Savvidou OD, Psarakis SA, Bernard PF, Triantafyllopoulos G, Kovanis I, Alexandropoulos P - J Med Case Rep (2007)

Bottom Line: Fractures of the neck of the femoral component have been reported in uncemented total hip replacements, however, to our knowledge, no fractures of the neck of a cementless forged titanium alloy femoral stem coated in the proximal third with hydroxy-apatite have been reported in the medical literature.This case report describes a fracture of the neck of a cementless forged titanium alloy stem coated in the proximal third with hydroxy-apatite.The neck of the femoral stem failed from fatigue probably because of a combination of factors described analytically below.

View Article: PubMed Central - HTML - PubMed

Affiliation: Orthopaedic Department, "Thriasio" General Hospital, G, Gennimata Avenue, Magula, 19600, Greece. grivastb@vodafone.net.gr.

ABSTRACT

Introduction: Fractures of the neck of the femoral component have been reported in uncemented total hip replacements, however, to our knowledge, no fractures of the neck of a cementless forged titanium alloy femoral stem coated in the proximal third with hydroxy-apatite have been reported in the medical literature.

Case presentation: This case report describes a fracture of the neck of a cementless forged titanium alloy stem coated in the proximal third with hydroxy-apatite.

Conclusion: The neck of the femoral stem failed from fatigue probably because of a combination of factors described analytically below.

No MeSH data available.


Related in: MedlinePlus

Intergranular fracture (region a).
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Figure 6: Intergranular fracture (region a).

Mentions: The examination of the stem and neck (figures 3 and 4) shows that this model has a neck machined for a better range of motion and impingement avoidance, with material removed mainly on the medial side, but machining extends also to the posterior and anterior aspects. Apparently, the fracture occurred at the smallest section of the neck, where the diameter is reduced to approximately 9.8 mm, corresponding to a surface area of 75 mm2. The laser etched markings lie on the anterior aspect of the stem, when used in a left hip. Additional laser etched markings are made on the neck, giving the indication relative to the characteristics of the cone (SEM 8. 00' and SpD2 = 12,45). These markings lie also on the anterior aspect, when the stem is implanted on a left hip. Scanning electron microscope figures of the fracture surface of the part supporting the head clearly show that the fracture has ended on the posterior side. Typical beach marks can be seen in the middle of the surface (arrows on figure 5). This beach marks are characteristic of the beginning of intergranular fracture, after a first stage of fatigue crack propagation. The second stage of the fracture consists in an intergranular fracture, located in the region marked a on figure 5, and shown more clearly in figure 6. The very last stage consists in a shear lip (marked region b in figure 5 and figure 7), oriented to 45° relative to the plane of intergranular fracture, and characteristic of the very end of the fracture due to shear stresses. Except for the intergranular fracture, which is very clear, the other fracture surfaces are smeared and polished from abrasive contact in vivo as enhanced by biological lubrication (see fragment contact in figure 2). Examination of the edges of the surface with a stereomicroscope reveals marks of tools, probably iatrogenically caused during retrieval of the implant. Unfortunately, these marks lie on the anterior aspect just in the vicinity of the laser markings, and interfere with possible other marks of fracture. Scanning electron microscope examination of the edge of the surface near the laser markings cannot show any clear evidence of initiation of fatigue fracture, mainly because of the tool marks and of the abraded surface in this region (figures 8 and 9). No typical striations could be found near the edge of the surface. The marks shown in figure 8 (near the "O") are more probably due to attrition because there are several such marks in this region, with different orientations.


Neck fracture of a cementless forged titanium alloy femoral stem following total hip arthroplasty: a case report and review of the literature.

Grivas TB, Savvidou OD, Psarakis SA, Bernard PF, Triantafyllopoulos G, Kovanis I, Alexandropoulos P - J Med Case Rep (2007)

Intergranular fracture (region a).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2235876&req=5

Figure 6: Intergranular fracture (region a).
Mentions: The examination of the stem and neck (figures 3 and 4) shows that this model has a neck machined for a better range of motion and impingement avoidance, with material removed mainly on the medial side, but machining extends also to the posterior and anterior aspects. Apparently, the fracture occurred at the smallest section of the neck, where the diameter is reduced to approximately 9.8 mm, corresponding to a surface area of 75 mm2. The laser etched markings lie on the anterior aspect of the stem, when used in a left hip. Additional laser etched markings are made on the neck, giving the indication relative to the characteristics of the cone (SEM 8. 00' and SpD2 = 12,45). These markings lie also on the anterior aspect, when the stem is implanted on a left hip. Scanning electron microscope figures of the fracture surface of the part supporting the head clearly show that the fracture has ended on the posterior side. Typical beach marks can be seen in the middle of the surface (arrows on figure 5). This beach marks are characteristic of the beginning of intergranular fracture, after a first stage of fatigue crack propagation. The second stage of the fracture consists in an intergranular fracture, located in the region marked a on figure 5, and shown more clearly in figure 6. The very last stage consists in a shear lip (marked region b in figure 5 and figure 7), oriented to 45° relative to the plane of intergranular fracture, and characteristic of the very end of the fracture due to shear stresses. Except for the intergranular fracture, which is very clear, the other fracture surfaces are smeared and polished from abrasive contact in vivo as enhanced by biological lubrication (see fragment contact in figure 2). Examination of the edges of the surface with a stereomicroscope reveals marks of tools, probably iatrogenically caused during retrieval of the implant. Unfortunately, these marks lie on the anterior aspect just in the vicinity of the laser markings, and interfere with possible other marks of fracture. Scanning electron microscope examination of the edge of the surface near the laser markings cannot show any clear evidence of initiation of fatigue fracture, mainly because of the tool marks and of the abraded surface in this region (figures 8 and 9). No typical striations could be found near the edge of the surface. The marks shown in figure 8 (near the "O") are more probably due to attrition because there are several such marks in this region, with different orientations.

Bottom Line: Fractures of the neck of the femoral component have been reported in uncemented total hip replacements, however, to our knowledge, no fractures of the neck of a cementless forged titanium alloy femoral stem coated in the proximal third with hydroxy-apatite have been reported in the medical literature.This case report describes a fracture of the neck of a cementless forged titanium alloy stem coated in the proximal third with hydroxy-apatite.The neck of the femoral stem failed from fatigue probably because of a combination of factors described analytically below.

View Article: PubMed Central - HTML - PubMed

Affiliation: Orthopaedic Department, "Thriasio" General Hospital, G, Gennimata Avenue, Magula, 19600, Greece. grivastb@vodafone.net.gr.

ABSTRACT

Introduction: Fractures of the neck of the femoral component have been reported in uncemented total hip replacements, however, to our knowledge, no fractures of the neck of a cementless forged titanium alloy femoral stem coated in the proximal third with hydroxy-apatite have been reported in the medical literature.

Case presentation: This case report describes a fracture of the neck of a cementless forged titanium alloy stem coated in the proximal third with hydroxy-apatite.

Conclusion: The neck of the femoral stem failed from fatigue probably because of a combination of factors described analytically below.

No MeSH data available.


Related in: MedlinePlus