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العنوان
Constrained acetabular component in total hip arthroplasty /
المؤلف
Hamed, Khaled Khairat.
هيئة الاعداد
باحث / Khaled Khairat Hamed
مشرف / Ahmed Emad Eldin Rady
مشرف / Tamer Abd Elmaguid Fayyad
مناقش / Tamer Abd Elmaguid Fayyad
تاريخ النشر
2014.
عدد الصفحات
104 P. :
اللغة
الإنجليزية
الدرجة
ماجستير
التخصص
جراحة العظام والطب الرياضي
تاريخ الإجازة
1/1/2014
مكان الإجازة
جامعة عين شمس - كلية الطب - قسم جراحة العظام
الفهرس
Only 14 pages are availabe for public view

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from 104

Abstract

The dislocation is a leading cause of failure after THA.Consrained liners was developed as an effective solution for dislocation after THR.The hip joint is supported by many ligaments and muscles.Hip abductors are very important for hip stability.The acetabular abduction angle and acetabular anteversion are important for positioning of the acetabular component.Two forces acting on the hip joint ,the abductors and the body weight.A common cuase for dislocation is malpositioning of the components,occurring most commonly during the first 3 months after index operation.Once dislocation occurs, approximately 25% of cases re-dislocate.Dislocation is either posterior or anterior.The underlying mechanism is impingement at the maximum extent of the primary arc of movement at the articulation interface.Many risk facrors responsible for dislocation some related to the patient and others to the surgery like muscle balance, cognitive disorders,surgical approach and component malpositioning.Once dislocation occurred ,closed reduction is the primary management.If failed ,open reduction or even revision should be considered.Many surgical solution available for treatment of instability after THA.Such as large femoral heads,modular component exchange and constrained liners.Constrained liners act by capturing the femoral head by the edge of the liner.This mechanism of action limits the ROM causes increased interfacial stresses and volumetric wear of the polyethelene cup.Constrained acetabular liners are typically indicated in cases of instability after THA when other causes are excluded.They are used as well in primary THA in patients with neuromuscular disorders and abductors dysfunction.The constrained liners are very effective solution for instability but ther is many drawbacks as discussed befor. Limited ROM leads to increased stress and wear leading to failure of the liner.The common mode of failure is type III which is failure of the femoral head-locking mechanism due to fracture or displacement of the locking ring.Reduction of dislocated acetabulare liner is more complicated than conventional one and usually needs open reduction.