Total hip replacements

Research based on Wolff s law of bone transformation has resulted in some other important observations. Fluctuating loads, such as those that occur in walking, are better for bone than consistentiy appUed loads, such as weight gain. However, if the effective appUed load becomes extreme, pressure necrosis, ie, bone death, occurs. Pressure necrosis is a significant concern in hip arthroplasty. Necrosis means the localized death of living tissue. Undue pressure on living cells causes death. Some total hip replacement failures are the direct result of pressure necrosis. 

Bechtol in reviewing his clinical experience with 1087 cemented Charnley and Bechtol total hip replacements concluded that prosthetic stem failure is actually the final sequence of previous failures of bony and cement support. His suggested sequence of events leading to prosthetic stem failure have been substantiated in the literature and are as follows ... 

Bechtol, C. O., Failure of Femoral Implant Components in Total Hip Replacement Operations , Orthopaedic Review, 4, 23-29 (1975)... 

The bisphosphonates are used to treat osteoporosis in postmenopausal women, Paget s disease of the bone, and postoperative treatment after total hip replacement (etidronate). 

Eriksson B. I., Kalebo P Anthmyr B. A., et al. Prevention of deep-vein thrombosis and pulmonary embolism after total hip replacement. Comparison of low molecular weight heparin and unfractionated heparin. J Bone Joint Surg [Am] 1991 73A, 484-93. 

Case Study of Materials Selection for Total Hip Replacement. Materials Department, Queen Mary and Westfield College, University of London, http //www.materials.qmul.ac.uk/casestud/implants/... 

Prophylaxis should be continued throughout the period of risk. For general surgical procedures and medical conditions, prophylaxis can be discontinued once the patient is able to ambulate regularly and other risk factors are no longer present. Most clinical trials support the use of antithrombotic therapy for 21 to 35 days after total hip replacement and hip fracture repair surgeries. 

Heterotopic ossification (etidronate) Prevention and treatment of heterotopic ossification following total hip replacement or caused by spinal injury. 

Complicating total hip replacement 20 mg/kg/day for 1 month preoperatively, then 20 mg/kg/day for 3 months postoperatively total treatment period is 4 months. 

Ghck HA, Connell ML, Koffer H, Eisenberg JM, Kelley MA. The economic impact of prophylaxis against venous thromboembolism in patients undergoing total hip replacement. Chn Res 1988 36 337A. 

Heterotopic ossification complicating total hip replacement PO 20 mg/kg/day for 1 mo before surgery then 20 mg g/day for 3 mo after surgery. 

Total hip replacement 20 mg/kg/d for 1 month before surgery and 3 months after surgery... 

Silane Crosslinking. Further, silane crosslinked UHMWPE has been used for acetabular cups for total hip replacements in goats. In this case, the number of in vivo debris particles appeared to be greater for crosslinked materials than conventional UHMWPE (29). 

An interesting finding regarding potentially toxic chromium (and cobalt) in the body is elevated blood and urine levels of these metals in patients who have undergone total hip replacement.5 The conclusion of the study was that devices such as prosthetic hips that involve metal-to-metal contact may result in potentially toxic levels of metals in biological fluids. 

Schaffer, A.W. et al., Increased blood cobalt and chromium after total hip replacement, J. Toxicol. Clin. Toxicol., 37, 839-844, 1999. 

StangierJ, Eriksson Bl, Dahl OE, etal. Pharmacokinetic profile of the oral direct thrombin inhibitor dabigatran etexilate in healthy volunteers and patients undergoing total hip replacement. J Clin Pharmacol 2005 45 555-563. 

Eriksson Bl, Dahl OE, Ahnfelt L, et al. Dose escalating safety study of a new oral direct thrombin inhibitor, dabigatran etexilate, in patients undergoing total hip replacement BISTRO I. J Thromb Haemost 2004 2 1573-1580. 

Elevated levels of chromium in blood, serum, urine, and other tissues and organs have been observed in patients with cobalt-chromium knee and hip arthroplasts (Michel et al. 1987 Sunderman et al. 1989). Whether corrosion or wear of the implant can release chromium (or other metal components) into the systemic circulation depends on the nature of the device. In one study, the mean postoperative blood and urine levels of chromium of nine patients with total hip replacements made from a cast cobalt-chromium-molybdenum alloy were 3.9 and 6.2 pg/F, respectively, compared with preoperative blood and urine levels of 1.4 and 0.4 pg/F, respectively. High blood and urinary levels of chromium persisted when measured at intervals over a year or more after surgery. These data suggest significant wear or corrosion... 

Coleman RF, Herrington J, Scales JT. 1973. Concentration of wear products in hair, blood, and urine after total hip replacement. Br Med J i 527-529. 

Two major clinical studies14 (621 patients who underwent elective total knee replacement, and 706 patients who underwent elective total hip replacement) have evaluated the efficacy and safety of rivaroxaban in the prophylaxis of thrombosis in patients undergoing orthopedic surgery. In these studies, rivaroxaban (2.5-10 mg b.i.d.) compared favorably with enoxaparin (40 mg once daily). 

Inhibition of abnormal calcification initials explorations of BPs as inhibitors of calcification showed promise, and early applications of etidronate included use in myositis ossificans, as well as in patients who had undergone total hip replacement surgery, in order to prevent subsequent heterotopic ossification and to improve mobility [10]. 

Refludan) jugular vein thrombus growth of thrombus growth compared to standard heparin et al. 1990 thrombosis after total hip replacement decreased rate of DVT et al. 1997... 

Learmonth ID. Biocompatibility a biomechanical and biological concept in total hip replacement. Surgeon 2003 1 1-8. 

Bonis LCHau(hO,JbigensaiLN, Lassen MR Enoxaparin versus dextran 70 in the prevention of postoperative deep vein thrombosis after total hip replacement. A Danish multicenter shkdy. Proceeding of the Danish Enoxaparin Symposium, Feb 3,1990... 

Eriksson BI, Zadirisson BE, Teger-Nilsson AC, Rish rg B Thrombosis prophylaxis with low molecular weight heparin in total hip replacement. BrJSurg (1988) 75(11) 10S3-10S7. 

LeyvrazPF, Richard J, BadmaonF, Van Melle O, Treyvaud JM, Livio JJ, Candardjis G Adjusted versus ficed suhcitaneous heparin in the i -evention of deep vein thrombosis after total hip replacement. N Eng JMed (1983) 309 954-958. 

Matzsch T, Bergqvist D, Fredin H, Hedner U Safety and efficacy of a low molecular weight heparin (Logiparin) versus dextran as ja-ophylaxis against thrombosis after total hip replacement. Acta Chirur... 

Eriksson BI, Wille-Jra-gensen P, Kalebo P, Mouret P, Rosendier N, Bosdi P, Baur M, Ekman S, Badi D, Lindratt S, Close P A comparison of recombinant hirudin with a low molecular weight heparin to prevent dvomboembolicoomfdi oiis after total hip replacement. iV ng/ JMed (1997) 337 1329-1335. 

Total hip replacement is an operation where the surgeon removes the rough surfaces of bone at the joint and replaces them with new smooth surfaces of the implant used. The modern hip replacement implant is complex and made of several components that the surgeon carefully fits together during surgery. Some of the components are made of metal and others of a special hard medical plastic. 

Regional damage from methylmethacrylate is generally the result of poor surgical technique, whereby the cement inadvertently reaches other tissues and structures. For example, leaking methylmethacrylate cement during fixation of the acetabular cup in a total hip replacement can cause sciatic nerve compression and result in severe lasting leg pain (5). 

Histaminfreisetzung und kardiovaskulare Reaktionen nach Implantation von Knochenzement bei totalem Huftgelenkersatz. [Histamine release and cardiovascular reactions to implantation of bone cement during total hip replacement.] Anaesthesist 1991 40(1) 25-32. 

Oleksak M, Edge AJ. Compression of the sciatic nerve by methylmethacrylate cement after total hip replacement. J Bone Joint Surg Br 1992 74(5) 729-30. 

Hayes A, Murphy DB, McCarroll M. The efficacy of singledose aprotinin 2 million KIU in reducing blood loss and its impact on the incidence of deep venous thrombosis in patients undergoing total hip replacement surgery. J Clin Anesth 1996 8(5) 357-60. 

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