BackgroundZ-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.FindingsThe 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.ConclusionsAlthough 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.

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Background:Malunion, nonunion, congenital abnormalities, and osteometabolic diseases are the main causes of long bone deformities1. Although the exact incidence is unclear, it is estimated that about 10% of all fractures have some complication in terms of fracture-healing. In addition to the aesthetic impact, malunions generally substantially impair function and quality of life1.Every malunion is unique, and treatment is usually planned according to the degree of deformity and the postoperative expectations of the patient2. However, it is noteworthy that deformity correction usually requires a high degree of surgical expertise. Several techniques have been proposed over the years, and new techniques that utilize current technologies are available, such as computer-assisted single-cut osteotomy3. In 2009, Russell et al. proposed the clamshell technique for diaphyseal malunions4-6. This technique is our preferred treatment for diaphyseal malunions and acute fractures in the setting of a previous malunion or deformity. The following videos will thoroughly describe the steps to perform this useful and effective surgical technique for malunion correction.Description:The key principle of the “clamshell osteotomy” is to create a comminuted fracture at the malunion site and utilize an intramedullary rod as a template for deformity correction4,5.Alternatives:Multiple osteotomy types and fixation methods are currently available for diaphyseal malunion correction. Among the osteotomies, opening or closing wedge, uniplanar, multiplanar, oblique, and dome methods may be utilized. In addition, several fixation methods can be utilized, including plates and screws, intramedullary rods, and external fixators2,6.Rationale:The clamshell technique is a useful and effective treatment option for diaphyseal malunions of the lower extremity. The ability to utilize an intramedullary nail as a template for deformity correction makes the procedure simpler than previously described techniques, which require perfect preoperative planning to avoid over- and undercorrection. The versatility of this procedure justifies its incorporation into the therapeutic arsenal for treatment of complex diaphyseal malunions.Expected Outcomes:To our knowledge, all previously reported cases utilizing the clamshell osteotomy have resulted in positive outcomes4-6. Russell et al. presented a case series of 10 patients with posttraumatic diaphyseal malunions (4 femoral and 6 tibial), in which all patients showed coronal and sagittal-plane correction to within 4°, limb-length inequality correction to within 2 cm, and complete correction of translation, rotation, and joint-line orientation angles4. In addition, all osteotomies healed uneventfully. The reported complications included broken interlocking screws in 1 case, need for dynamization in 1 case, and superficial wound dehiscence in 2 cases (1 of which required surgical debridement). Pires et al. presented 4 cases of clamshell osteotomies performed for the treatment of acute fractures in the setting of a previou...

Complex lower extremity trauma with large soft tissue defects requires early wound coverage to reduce the risk of complications. In particular circumstances, however, local or free flaps may be contraindicated due to local or systemic issues. This study presents a helpful and effective salvage procedure for soft tissue reconstruction that uses autologous fat grafting combined with negative pressure wound therapy. Level of Evidence V; Therapeutic Studies; Expert Opinion.