Acetabular, Fractures

With the increased use of CT, further simplified approaches to acetabular fractures have been proposed (Harris et al. 2004a,b). 

Fig. 12.22a-j. Acetabular fractures. Elementary group (a) posterior wall, (b) anterior wall, (c) posterior column, (d) anterior column, (e) transverse. Complex group (f) posterior column and posterior wall, (g) both columns, (h) transverse and posterior wall, (i) T shaped, (j) anterior column and posterior hemi-transverse... 

With a displaced acetabular fracture, open reduction, stable internal fixation and early motion is often indicated. Reduction of a femoral head dislocation should be paramount, as there is a relationship between the occurrence of avascular necrosis and prolonged dislocation (Heeg et al. 1989). Recurrent dislocation may occur from a capsular defect, loose fragments within the joint and remodelling of the joint. 

Hallel T, Salvati EA (1977) Premature closure of the triradiate cartilage. A case report and animal experiment. Clin Orthop Relat Res (124) 278-281 Harley JD, Mack LA, et al. (1982) CT of acetabular fractures comparison with conventional radiography. AJR Am J Roentgenol 138 413-417... 

Harris JH Jr, Coupe KJ, et al. (2004) Acetabular fractures revisited part 2, a new CT-based classification. AJR Am J Roentgenol 182 1367-1375... 

Wedegartner U, Gatzka C, Rueger JM, Adam G (2003) Multislice CT (MSCT) in the detection and classification of pelvic and acetabular fractures. Rofo 175 105-111 Wintermark M, Mouhsine E, Theumann N, Mordasini P, van Melle G, Leyvraz PF, Schnyder P (2003) Thoracolumbar spine fractures in patients who have sustained severe trauma depiction with multi-detector row CT. Radiology 227 681-689... 

The use of alfernafive bearings entails potential risks for the patient. With MOM bearings, the concern is the potential for cancer associated with longterm elevated metal ion exposure. With COC, the concern is the risk of fracture for the femoral head and/or the acetabular liner. With highly crosslinked UHMWPE, following extensive multi-institutional testing, researchers have not yet been able to determine the risks relative to conventional UHMWPE for hip replacements. 

The AP radiograph should be closely reviewed for signs of pelvic ring discontinuity by identifying various anatomical lines, the absence of which implies ring disruption or a fracture. These lines are the ischio-ilial line, ilio-pectineal line, and the anterior and posterior acetabular walls. The ilio-ischial line is formed by the posterior structures of the pelvis and the ilio-pectineal by the anterior acetabular structures (Ersoy et al. 1995) (Fig. 12.3). 

Approximately 30% of pelvic fractures seen on CT can be missed on plain films (Resnik et al. 1992 Berg et al. 1996). In particular, AP radiographs may miss sacroiliac diastasis, acetabular, intra-articular and vertical shear fractures (Montana et al. 1986 ... 

CT is important for detecting small fractures of the acetabulum, looking for acetabular displacement and also for detecting intra-articular foreign bodies. 

Percutaneous cementoplasty (PC) consists of injecting acrylic cement (polymethylmethacrylate) in bone and is a perfect example of a minimally invasive technique in the musculoskeletal system. PC has been performed since 1984. Its role is to consolidate weight-bearing bone and to treat pain. Bone packing with acrylic cement is a procedure aimed at preventing pathological fractures and pain in patients with vertebral body lesions and acetabular metastasis. 

A great disadvantage, however, is the limited service Ufe of acetabular sockets made from PE-UHMW, Table 5.130. In approx. 30% of all PE-UHMW hip joint sockets implanted, complications developed after eleven years. In addition to fractures of acetabular sockets, abrasion and creep were the main problems encountered. While in-vitro investigations revealed relatively low abrasion rates of 0.2 to 0.9 j/m/year, abrasion rates as high as 150 to 200 fita were detected in in-vivo investigations on PE-UHMW in combinations with steel or ceramics [970]. 

Osteochondritis, mandibular cysts, ankle-foot fracture, calcaneus cystic lipoma, acetabular revision, tumoral cavities... 

The main limitations of the alumina/UHMWPE pair are their sensitivity to the watery means, which can cause static fatigue, and their low resistance to the fracture, that can get to be critical in zones of stress concentrations. These conditions are present in the hip implants (watery atmosphere, severe cycles of tensions, overloads, impacts, etc.)[20,21]. Nevertheless, the main problem is the relaxation of the acetabular component with emission of particles. These particles are accumulated and been able to induce very adverse tissue reactions. 

RegenOss JRI Orthopaedics) Type I coUagen Hbres Mg-rich, nano-HA Long bone fractures, revision hip arthroplasty to fill acetabular defects and spinal fusion... 

Starting in lune 2000, a new alumina matrix nanocomposite material (BIOLOX Delta, CeramTec, Plochingen, Germany) has been available as a femoral head material [101]. This ceramic biomaterial is now broadly used across the orthopedic industry in both femoral heads and acetabular liners. According to the manufacturer, more than 320,000 femoral heads and 160,000 acetabular inserts have been implanted on a worldwide basis as of 2008 [106]. The primary advantage of this alumina matrix composite is its increased strength, fracture toughness, and wear resistance relative to alumina (Table 6.2) [112]. 

Over the past 8 years, a few reports of rim fracture of remelted crosslinked liners have surfaced in the literature [174, 175], as well as in FDA Maude reports (see http // www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfMAUDE/ search.CFM). These case reports are usually associated with thin liners associated with acetabular shells implanted with a high abduction angle. Due to the small numbers reported thus far in the literature, the incidence of rim fracture necessitating revision of crosslinked polyethylenes remains poorly understood. None of the numerous clinical studies of remelted polyethylenes have reported rim fracture as a clinically relevant failure mode. However, the few rare cases of rim fracture have provided motivation for improving the mechanical behavior of crosslinked polyethylenes, especially for thin liners. 

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