Protrusio acetabuli is the protrusion of the acetabulum into the pelvic cavity. With the medial movement of the acetabulum, the femoral head also shifts into the pelvis. Although the condition was first recognized in 1816, it was not until 120 years later that it was classified into primary (idiopathic) and secondary disease[1]. By today, a large number of conditions are known to cause secondary protrusio acetabuli [1]; the category of primary protrusio acetabuli is maintained for cases whose origins cannot be attributed to other diseases. As diagnostic techniques keep improving, the number of primary cases keeps decreasing [2].

Infections by gonoccous and echinococcus as well as tuberculosis were found early on to cause protrusio acetabuli. The main inflammatory conditions that cause protrusio acetabuli are rheumatoid arthritis [3], ankylosing spondylitis [4], psoriatic arthritis, acute idiopathic chondrolysis, and Reiter’s syndrome. A number of metabolic diseases are also associated with protrusio acetabuli. Among these are osteogenesis imperfecta, osteoporosis, hyperparathyroidism, and Paget’s disease. Some genetic ailments associated with protrusio acetabuli are sickle cell disease [5], trisomy 18, Ehlers-Danlos syndrome, and Marfan’s disease. Neoplastic disease and trauma to the bone, such as fractures, can also result in protrusio acetabuli [6].

Primary protrusio acetabuli is caused by deficiency or destruction of the bone structure or developmental abnormalities. It can be the source of osteoarthritis; senile patients with protrusio acetabuli almost always report with osteoarthritis [7]. Primary protrusio acetabuli is most frequently bilateral and affects women more than men. Several familial cases have been reported which were compatible with an autosomal dominant inheritance pattern [2]. Primary protrusio acetabuli showcases mainly with stiffness, limitation of movement, and possibly pain [2].

• Anemia

  The authors conclude that sickle-cell anemia can predispose to development of protrusio acetabuli. [ncbi.nlm.nih.gov]

  Protrusion of the acetabulum is relatively frequent in patients with sickle cell anemia. [rrnursingschool.biz]

• Reiter Syndrome

  The prevalence and characteristics of PA were studied in 50 adults and 25 children with SNSA (40 ankylosing spondylitis, 24 psoriatic arthropathy, and 11 Reiter's syndrome). [ncbi.nlm.nih.gov]

  The prevalence and characteristics of PA were studied in 50 adults and 25 children with SNSA (40 ankylosing spondylitis, 24 psoriatic arthropathy, and 11 Reiter's syndrome}. [kundoc.com]

  The main inflammatory conditions that cause protrusio acetabuli are rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, acute idiopathic chondrolysis, and Reiter’s syndrome. [symptoma.com]

  ’s syndrome ü Osteolysis following hip Replacement Metabolic ü Paget’s disease ü Osteogenesis imperfecta ü Ochronosis ü Acrodysostosis ü Osteomalacia (very high incidence –50%) ü Hyperparathyroidism Traumatic ü Sequalae of acetabular fracture ü Surgical [orthopaedicprinciples.blogspot.com]

• Marfanoid Habitus

  A wide range of musculoskeletal involvement occurs including marfanoid habitus, kyphosis, scoliosis, slipped epiphyses, joint laxity and degenerative arthritis. Congenital myopia and micrognathia are the most characteristic non-skeletal features. [ncbi.nlm.nih.gov]

• Dysostosis

  Abstract Progressive protrusio acetabuli in a patient with acrodysostosis (peripheral dysostosis Type 12) has not, as far as we know, been reported previously. [ncbi.nlm.nih.gov]

• Pelvic Mass

  BACKGROUND: The differential diagnosis in an elderly woman with a complex pelvic mass includes benign and malignant diseases. CASE: A woman in her ninth decade was discovered to have both a breast mass and a pelvic mass at examination. [ncbi.nlm.nih.gov]

  Conclusion: Protrusio Acetabuli Prosthetica can present as pelvic mass without any other associated symtoms. Although a rare complication, with noted morbidity, it might still be reconstructable. [jocr.co.in]

  The presence of any pelvic mass in association with total hip replacement should prompt consideration of presence of protrusio acetabuli and associated vascular pathology. CT can highlight any associated pelvic mass and thrombosis within vessels. [docksci.com]

  And the case for arthroscopic treatment of global pincer impingement. ( 22551946 ) Matsuda D.K. 2012 15 Protrusio Acetabuli Prosthetica - a cause of a Pelvic Mass Presenting to the Gynaecologist. ( 27298861 ) 2012 16 Protrusio acetabuli and total hip [malacards.org]

• Thrombosis

  We present a case of severe prosthetic migration with the formation of haematoma and impingement on iliac vessels leading to thrombosis and subsequent pulmonary embolus. [ncbi.nlm.nih.gov]

  CT can highlight any associated pelvic mass and thrombosis within vessels. The prevention of further deep vein thrombosis requires treatment of the prosthetic abnormality and removal of associated mass. [docksci.com]

  Post-operatively he developed a large right-sided ilio-femoral deep venous thrombosis. [researchgate.net]

• Ectopia Lentis

  Two patients had simultaneously ectopia lentis and myopia. [researchgate.net]

• Coxa Vara

  Observe intense osteoporosis, severe coxa vara deformity, and dislocated fracture of the right femoral shaft Fig. 4.19. Osteogenesis imperfecta in a 16-year-old girl. [rrnursingschool.biz]

  vara and decreased femoral anteversion Treatment Depends on age and degree of degenerative changes Medial wall bone grafts Joint replacement surgery may be necessary Acetabular Protrusio. [learningradiology.com]

• Flexion Contracture

  Abstract The family of a child who developed symptoms and flexion contractures with protrusio acetabuli rapidly between the age of 8 and 11 was examined. [ncbi.nlm.nih.gov]

  (From Leroy et al. 1998) lescence or adulthood, and range from none to severe hip pain, limitation of hip motion, flexion contracture, and abnormal gait. [rrnursingschool.biz]

• Oligoarthritis

  Such a mode of presentation has not been described previously in the context of childhood chronic inflammatory arthritides, and may represent a separate oligoarthritis subtype of JIA. [ncbi.nlm.nih.gov]

  The older age of onset of our reported cohort with an oligoarthritis pattern contrasts with the peak of onset of age of 2–3 yr for the common or classical oligoarthritis JIA subtype. [academic.oup.com]

• Decrease in Height

  However, the study group had more women, decreased mean height and weight, and lower preoperative Merle d'Aubigné-Postel scores, which were inherent differences at the time of first presentation. [ncbi.nlm.nih.gov]

  However, the study group had more women, decreased mean height and weight, and lower preoperative Merle d’Aubigné-Postel scores, which were inherent differences at the time of first presentation. [researchgate.net]

• Lordosis

  Systemic lupus erythematosus ( Drug-induced ) - Dermatomyositis ( Juvenile dermatomyositis ) - Polymyositis - Scleroderma - Sjögren's syndrome - Behçet's disease - Polymyalgia rheumatica - Eosinophilic fasciitis - Hypermobility Dorsopathies Kyphosis - Lordosis [bionity.com]

• Breast Mass

  CASE: A woman in her ninth decade was discovered to have both a breast mass and a pelvic mass at examination. After diagnostic breast biopsy results that confirmed invasive breast carcinoma, pelvic examination and ultrasonography were performed. [ncbi.nlm.nih.gov]

• Stroke

  Author information 1 Division of Cardiology, Department of Medicine, Heart Vascular Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea. 2 Division of Cardiology, Department of Medicine, Heart Vascular Stroke [ncbi.nlm.nih.gov]

  Unusual association of diseases/symptoms CASE REPORT Protrusio acetabuli: a rare cause of pulmonary embolus Colm Murphy,1 Barry James O’Neill,2 John Francis Quinlan,2 Ronan Collins1 1 Stroke Unit and Department of Gerontology, Adelaide & Meath Hospital [docksci.com]

• Neglect

  These pathological alterations are responsible for neglecting MLD 46 in most studies on the postcranium of A. africanus. [researchgate.net]

• Foot Drop

  drop, Flat feet, Club foot, Unequal leg length, Winged scapula) patella (Luxating patella, Chondromalacia patellae ) Protrusio acetabuli - Hemarthrosis - Arthralgia - Osteophyte Systemic connective tissue disorders Polyarteritis nodosa - Churg-Strauss [bionity.com]

Workup has to start with a thorough history (including family history), and careful physical examination of the hip. Blood tests (such as complete blood count, the presence of C-reactive protein) and synovial biopsy will aid in the diagnosis. An anteroposterior radiogram is the most usual diagnostic tool, using plain radiography. Some investigators advocate the use of the false profile view, which reveals excessive cartilage destruction [8]. Magnetic resonance arthrography is useful for the detection of structural changes in the early stages of the disease.

In young patients, the condition is difficult to diagnose because the radiological signs are not characteristic. The difficulty also lies in differentiating protrusio acetabuli from acute idiopathic chondrolysis. With complaints of stiffness and pain – and with secondary causes, such as inflammation and trauma excluded –young people would be diagnosed with idiopathic chondrolysis if they display loss of joint space. If they also exhibit signs of an acetabular protrusion in addition to the loss of joint space, the diagnosis is protrusio acetabuli. Some investigators regard protrusio acetabuli and idiopathic chondrolysis as the same condition [9]; however, for various reasons, this view is not universally accepted. For example, idiopathic chondrolysis does not show a female preponderance [2].

A critical measurement for diagnosis deduced from radiographs is the center-edge angle of Wiberg [2], which is between 25 and 40 degrees in normal hips. An angle of more than 46 degrees indicates protrusio acetabuli. However, several authors find the angle measurement inadequate for diagnosis; for example, angles greater than 46 degrees can also be found in the general population [10]. Another important indication of protrusio acetabuli is the extent to which the medial wall of the acetabulum shifts medially in relation to the ilioischial line (Kohler’s line). Some investigators require the acetabular wall to reach the ilioischial line, while others call for the line to be crossed to establish the diagnosis. Yet another widely used criterion is the arrangement of the teardrop. Using the above criteria for diagnosis requires the careful centering of radiographic images. Other anatomical criteria can be used. A grading of the protrusion is provided by determination of the distance of the acetabulum from the upper margin of the superior pubic ramus [11].

• HLA-B27

  None were considered to have a specific subtype of juvenile idiopathic arthritis (JIA) and all tested were negative for HLA-B27. Elevation of serum inflammatory markers was variable. Protrusio acetabuli was the predominant radiological feature. [ncbi.nlm.nih.gov]

  Cases would be excluded if found to be HLA-B27-positive, to fulfil criteria for other forms of JIA (other than oligoarthritis), or to have a family history of HLA-B27-associated disease or psoriasis or psoriatic arthritis. [academic.oup.com]

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2. Dunlop CC, Jones CW, Maffulli N. Protrusio acetabuli. Bull Hosp Jt Dis. 2005;62:105-114.
3. Vaishya R. Bilateral protrusio acetabuli of the hip. BMJ Case Rep. 2014 Mar 17;2014.
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9. Sherlock DA. Acute idiopathic chondrolysis and primary acetabular protrusio may be the same disease. J Bone Joint Surg Br. 1995 May;77(3):392-395.
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11. Sotelo-Garza A, Charnley J. The results of Charnley arthroplasty of hip performed for protrusio acetabuli. Clin Orthop Relat Res. 1978 May;(132):12-18.