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Protrusio Acetabuli

Protrusio acetabuli is a distortion of the hip where the acetabulum and femoral head migrate into the pelvic cavity. The disease can be idiopathic (primary) or can be secondary to a number of conditions, such as trauma, inflammation or other diseases. The cornerstone of diagnosis is anteroposterior radiography and the treatment varies by age. For the skeletally immature youth, a fusion of the triradiate cartilage may be recommended but is not frequently carried out because the protrusion does not always deteriorate. For young adults, valgus intertrochanteric osteotomy is performed. For older patients, total joint replacement is the procedure of choice.


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].

  • The authors conclude that sickle-cell anemia can predispose to development of protrusio acetabuli.[ncbi.nlm.nih.gov]
  • We have described a patient with sickle cell anemia who had this complication probably as a result of osteopenia. Thus sickle cell anemia should be added to the list of potential causes of protrusio acetabuli.[ncbi.nlm.nih.gov]
  • Protrusion of the acetabulum is relatively frequent in patients with sickle cell anemia.[rrnursingschool.biz]
  • Bilateral protrusio acetabuli in sickle cell anemia. South Med J 1990 ; 83 : 328 –9. 27 Mandell GA, Harcke HT, Scott CI, Caro PA, Einsig HJ, Bowen JR. Protrusio acetabuli in neurofibromatosis: nondysplastic and dysplastic forms.[academic.oup.com]
Reiter's 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 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]
Pelvic Mass
  • The differential diagnosis in an elderly woman with a complex pelvic mass includes benign and malignant diseases. 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]
  • 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]
  • Abstract Favorites PDF Get Content & Permissions Hip Arthroscopy Complicated by a Deep Vein Thrombosis in a Patient with May-Thurner Syndrome Lieberman, Elizabeth G.; Bell, Courtney D.; Herzka, Andrea JBJS Case Connector. 8(3):e57-e57, September 2018.[journals.lww.com]
  • Preoperatively, joint space narrowing and osteophytes were more frequent posteroinferior (joint space narrowing 18% versus 2%, p 0.008; osteophytes 21% versus 4%, p 0.007), medial (joint space narrowing 33% versus 5%, p 0.001) and anterior (osteophytes[ncbi.nlm.nih.gov]
  • At the age of 16 the proband underwent bilateral total replacement arthroplasty; histologically the changes were those of fibrocartilaginous replacement and osteophyte formation.[ncbi.nlm.nih.gov]
  • Although the superior joint space on the false profile views was still normal with little osteophytic reaction, the posteroinferior joint space was clearly narrowed in four hips (Fig. 4 A), an argument against joint-preserving surgery.[ncbi.nlm.nih.gov]
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]
Ectopia Lentis
  • The presence of PA did not correlate with the presence of ectopia lentis, aortic root diameter, or history of aortic dissection. The presence of PA did not have a significant impact on the final diagnosis of MFS.[ncbi.nlm.nih.gov]


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].


  • A detailed history and physical examination revealed previous radiation treatment of prostate cancer requiring extensive preoperative workup and consultation.[ncbi.nlm.nih.gov]
  • In addition, this book covers epidemiology and mechanisms of injury, diagnosis, treatment principles, avoidance of pitfalls, rehabilitation, outcome assessment, economics of hip fracture treatment and prevention.[books.google.ro]
  • TREATMENT • Adolescent or Young Adult Patients: VITO by Pauwels 8.[slideshare.net]
  • Treatment of the condition is contingent upon (1) reestablishment of the radiographically determined anatomic position of the acetabulum and (2) construction of a medial prosthetic or biologic buttress.[ncbi.nlm.nih.gov]


  • It is concluded that PA is a frequent complication in SNSA; however, its presence does not seem to modify the functional prognosis of these patients.[ncbi.nlm.nih.gov]
  • The prognosis in untreated dysplasia of the hip. A study of radiographic factors that predict the outcome. J Bone Joint Surg Am (1995) 77 (7):985–9. Google Scholar 24. Nunley RM, Prather H, Hunt D, Schoenecker PL, Clohisy JC.[frontiersin.org]


  • A genetic etiology has been proposed in developmental dysplasia of the hip, while the etiology of primary protrusio acetabuli is widely debated.[ncbi.nlm.nih.gov]
  • Adrenal cortical steroids may play a significant role in the etiology of this condition in rheumatoid arthritis.[ncbi.nlm.nih.gov]
  • This is the first case seen in the literature, despite various studies conducted about the etiology, no common factor was found.[turkosteoporozdergisi.org]
  • It is important to consider all etiologic possibilities before evaluating treatment options.[ncbi.nlm.nih.gov]


  • In addition, this book covers epidemiology and mechanisms of injury, diagnosis, treatment principles, avoidance of pitfalls, rehabilitation, outcome assessment, economics of hip fracture treatment and prevention.[books.google.ro]
  • INCIDENCE AND EPIDEMIOLOGY It is more frequent in female (10:1), and bilateral; is very common in advanced rheumatoid arthritis patients (1) .[scielo.br]
Sex distribution
Age distribution


  • These terms are essentially descriptive and ambiguous in the sense that they do not impart information regarding the likely pathophysiology of the disease.[academic.oup.com]


  • Early operation on those patients showing rapid development of protrusio may prevent complications.[ncbi.nlm.nih.gov]
  • In addition, this book covers epidemiology and mechanisms of injury, diagnosis, treatment principles, avoidance of pitfalls, rehabilitation, outcome assessment, economics of hip fracture treatment and prevention.[books.google.ro]
  • Gel foam strips were then placed around the periphery of the graft to prevent interposition of cement between it and the articular surface.[mjdrdypu.org]
  • Also included is a special in-depth chapter on medical malpractice offering expert guidance on legal issues and principles, malpractice perspectives and prevention and informed consent.[books.google.de]



  1. Leunig M, Nho SJ, Turchetto L, Ganz R. Protrusio acetabuli: new insights and experience with joint preservation. Clin Orthop Relat Res. 2009 Sep;467(9):2241-2250.
  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.
  4. Dwosh IL, Resnick D, Becker MA. Hip involvement in ankylosing spondylitis. Arthritis Rheum. 1976 Jul-Aug;19(4):683-692.
  5. Martinez S, Apple JS, Baber C, Putman CE, Rosse WF. Protrusio acetabuli in sickle-cell anemia. Radiology. 1984 Apr;151(1):43-44.
  6. Gillard AJ, Deyle GD. Acetabular fracture and protrusio acetabuli in an elderly patient following a fall. J Orthop Sports Phys Ther. 2009 Sep;39(9):703.
  7. Hooper JC, Jones EW. Primary protrusion of the acetabulum. J Bone Joint Surg Br. 1971 Feb;53(1):23-29.
  8. Lequesne MG, Laredo JD. The faux profil (oblique view) of the hip in the standing position. Contribution to the evaluation of osteoarthritis of the adult hip. Ann Rheum Dis. 1998 Nov;57(11):676-681.
  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.
  10. Armbuster TG, Guerra J Jr, Resnick D, et al. The adult hip: an anatomic study. Part I: the bony landmarks. Radiology. 1978 Jul;128(1):1-10.
  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.

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Last updated: 2018-06-22 04:30