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Failure of fixation of trochanteric femur fractures: Clinical recommendations for avoiding Z-effect and reverse Z-effect type complications.

Pires RE, Santana EO, Santos LE, Giordano V, Balbachevsky D, Dos Reis FB - Patient Saf Surg (2011)

Bottom Line: Literature-based explanations for this phenomenon are provided together with recommendations of how to avoid such complications.Although intramedullary fixation is an established method of treatment of femoral intertrochanteric and subtrochanteric fractures, the evolution of the procedure may include complications associated with the migration of the interlocking head screws.The occurrence of Z-effect and reverse Z-effect has not been completely elucidated, but the main causes of such complications are probably fracture fixation in varus position, severe medial comminution, inappropriate entry point of the nail and poor bone quality.

View Article: PubMed Central - HTML - PubMed

Affiliation: Hospital Felício Rocho, Av, do Contorno 9790, 30110-060, Belo Horizonte, MG, Brasil. robinsonesteves@ig.com.br.

ABSTRACT

Background: Z-effect and reverse Z-effect are complications that arise from the surgical treatment of pertrochanteric fractures of the femur with proximal femoral nails (PFN) comprising two interlocking head screws. Such complications are induced by the migration of screws in opposite directions, which may lead to failure of the osteosynthesis.

Findings: The paper describes three cases of pertrochanteric fractures that were treated with PFN with two interlocking screws that evolved to either Z-effect or reverse Z-effect. Literature-based explanations for this phenomenon are provided together with recommendations of how to avoid such complications.

Conclusions: Although intramedullary fixation is an established method of treatment of femoral intertrochanteric and subtrochanteric fractures, the evolution of the procedure may include complications associated with the migration of the interlocking head screws. The occurrence of Z-effect and reverse Z-effect has not been completely elucidated, but the main causes of such complications are probably fracture fixation in varus position, severe medial comminution, inappropriate entry point of the nail and poor bone quality.

No MeSH data available.


Related in: MedlinePlus

Case 3 - Radiographies of the left hip joint showing the correct consolidation of the left intertrochanteric femoral fracture (A), together with the lateral migration of the superior screw while the sliding screw remained in the original position. The removal of the superior screw is shown in (B).
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Figure 3: Case 3 - Radiographies of the left hip joint showing the correct consolidation of the left intertrochanteric femoral fracture (A), together with the lateral migration of the superior screw while the sliding screw remained in the original position. The removal of the superior screw is shown in (B).

Mentions: An 80-year old housewife was injured in a fall resulting in lateral trauma of the left hip that was diagnosed as an intertrochanteric fracture of the left femur (AO/OTA 31-A2.1). The patient had a history of ischemic cardiomyopathy and had undergone angioplasty and vascular stenting, and was receiving a daily dose of Clopidogrel® (75 mg). The patient was submitted to osteosynthesis with PFN (Synthes®, Rio Claro, SP, Brazil) one day after the trauma and evolved with fracture consolidation in a favorable position. After surgery, the patient returned to normal functional activities but the superior screw migrated laterally after 6 months. Although the inferior screw remained in the normal position the cranial screw migrated, probably owing to poor bone quality. The superior screw was removed after consolidation of the fracture. Since the sliding screw was well positioned with regard to the tip apex distance, and the fracture was adequately reduced, no failure in osteosynthesis occurred. Radiographic images are presented in Figure 3.


Failure of fixation of trochanteric femur fractures: Clinical recommendations for avoiding Z-effect and reverse Z-effect type complications.

Pires RE, Santana EO, Santos LE, Giordano V, Balbachevsky D, Dos Reis FB - Patient Saf Surg (2011)

Case 3 - Radiographies of the left hip joint showing the correct consolidation of the left intertrochanteric femoral fracture (A), together with the lateral migration of the superior screw while the sliding screw remained in the original position. The removal of the superior screw is shown in (B).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3142479&req=5

Figure 3: Case 3 - Radiographies of the left hip joint showing the correct consolidation of the left intertrochanteric femoral fracture (A), together with the lateral migration of the superior screw while the sliding screw remained in the original position. The removal of the superior screw is shown in (B).
Mentions: An 80-year old housewife was injured in a fall resulting in lateral trauma of the left hip that was diagnosed as an intertrochanteric fracture of the left femur (AO/OTA 31-A2.1). The patient had a history of ischemic cardiomyopathy and had undergone angioplasty and vascular stenting, and was receiving a daily dose of Clopidogrel® (75 mg). The patient was submitted to osteosynthesis with PFN (Synthes®, Rio Claro, SP, Brazil) one day after the trauma and evolved with fracture consolidation in a favorable position. After surgery, the patient returned to normal functional activities but the superior screw migrated laterally after 6 months. Although the inferior screw remained in the normal position the cranial screw migrated, probably owing to poor bone quality. The superior screw was removed after consolidation of the fracture. Since the sliding screw was well positioned with regard to the tip apex distance, and the fracture was adequately reduced, no failure in osteosynthesis occurred. Radiographic images are presented in Figure 3.

Bottom Line: Literature-based explanations for this phenomenon are provided together with recommendations of how to avoid such complications.Although intramedullary fixation is an established method of treatment of femoral intertrochanteric and subtrochanteric fractures, the evolution of the procedure may include complications associated with the migration of the interlocking head screws.The occurrence of Z-effect and reverse Z-effect has not been completely elucidated, but the main causes of such complications are probably fracture fixation in varus position, severe medial comminution, inappropriate entry point of the nail and poor bone quality.

View Article: PubMed Central - HTML - PubMed

Affiliation: Hospital Felício Rocho, Av, do Contorno 9790, 30110-060, Belo Horizonte, MG, Brasil. robinsonesteves@ig.com.br.

ABSTRACT

Background: Z-effect and reverse Z-effect are complications that arise from the surgical treatment of pertrochanteric fractures of the femur with proximal femoral nails (PFN) comprising two interlocking head screws. Such complications are induced by the migration of screws in opposite directions, which may lead to failure of the osteosynthesis.

Findings: The paper describes three cases of pertrochanteric fractures that were treated with PFN with two interlocking screws that evolved to either Z-effect or reverse Z-effect. Literature-based explanations for this phenomenon are provided together with recommendations of how to avoid such complications.

Conclusions: Although intramedullary fixation is an established method of treatment of femoral intertrochanteric and subtrochanteric fractures, the evolution of the procedure may include complications associated with the migration of the interlocking head screws. The occurrence of Z-effect and reverse Z-effect has not been completely elucidated, but the main causes of such complications are probably fracture fixation in varus position, severe medial comminution, inappropriate entry point of the nail and poor bone quality.

No MeSH data available.


Related in: MedlinePlus