Total hip

The next advance in total hip arthroplasty came with the development of various porous surface treatments which allow bone tissue to grow into the metal porous coating on the femoral stem of the hip implant and on the acetabular component of the total joint replacement. These developments arose because of patients who were not able to tolerate cemented implants because of allergies to the cement, methylmethacrylate. More youthflil patients are better served by a press-fit implant as well. Figure 12 shows the difference between textured and beaded surface-treated orthopedic prostheses. 

The acetabular component is as integral to successful total hip arthroplasty as is the femoral hip stem component. The life of the acetabular component depends on proper placement and bone preparation in the acetabular region of the hip girdle, proper use of bone cement, and superior component design. 

The head of the femoral component then articulates with an ion-bombarded, HDPE, high walled, acetabular liner which fits iato a screwed ia, machined, titanium, chromium—cobalt—molybdenum or vanadium—aluminum metallic alloy hydroxyapatite-coated acetabular shell/cup. Each of the separate parts of the modular system for total hip arthroplasty is manufactured ia several different sizes. 

Total hip implants of the nature described have hospital Hst prices ia the range of 5000— 8000. Fully custom-made implants cost approximately 10,000. The low end basic total hip implant is forged or cast stainless steel, cemented ia place, one size fits all, and costs 1000. 

Resorption of bone tissue occurs in total hip joint replacement patients if sufficient stresses are not adequately transmitted to the remaining bone in exactiy the same way that the bone transmitted those stresses originally. Therefore, the design and proper placement of the neck coUar and hip stem must be effective in recreating anatomical stmcture. 

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. 

One of the main problems of corrosion testing in-vivo and the interpretation of the mechanisms of corrosion which have taken place in-vivo after the implant has been removed from a patient is well illustrated in Figure 2.35 used by Semlitsch and Willet to illustrate the types of corrosion which are associated with a total hip joint replacement. This figure shows that many corrosion mechanisms could be taking place simultaneously in a system of this nature. 

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. 

All women included in MORE met criteria for osteoporosis defined as a lumbar spine or femoral neck bone mineral density (BMD) T score equal to or less than 2.5 or as the presence of a radiographic vertebral fracture. These women are considered to be at lower risk for breast cancer than women with normal BMD since this parameter could partially reflect a woman s lifetime exposure to estrogens (Zhang et al. 1997). After the start of MORE, NHANES III criteria standardizing total hip BMD measurements became available allowing part of... 

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. 

Reduction of weight, dietary fat intake, alcohol intake, and dose may reverse the effects on serum triglycerides, allowing patients to continue therapy. Musculoskeletal effects In a clinical trial (N = 217) of a single course of therapy for isotretinoin, 7.9% of patients had decreases in lumbar spine bone mineral density greater than 4%, and 10.6% of patients had decreases in total hip bone mineral density greater than 5%. 

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. 

Mechanical pain and disability due to permanent joint deformities require joint orthosis. Long-term relief of pain and improvements of function have been achieved with total hip, knee, shoulder, wrist and multiple joint replacements. 

Total hip surgery Subcutaneous 2500 international units 1-2 hr before surgery, then 2500 units 6 hr after surgery, then 5000 units/dayfor 7-10 days. 

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. 

Metallic biomaterials (metals such as Ti or its alloys and others) are used for the manufacture of orthopaedic implants due to their excellent biocompatibility with respect to electrical and thermal conductivity and their mechanical properties, e.g., for hard tissue replacement such as total hip and knee joints, for fracture healing aids such as bone plates and screws or dental implants. For example, Co-Cr-Mo alloys are employed for metal-on-metal hip bearings in total joint replacements. Problems with implants occur because of ion release in patients with metal implants. To control this ion release, the ultratrace determination of Co, Cr and Mo in the blood (or serum) and urine of patients with Co-Cr-Mo alloy hip implants is carried out routinely in the author s laboratory. The trace metal determination of Co, Cr and Mo in complex matrices such as urine and blood by ICP-MS is not trivial due to the low concentrations expected in the sub-ngmF1 range, the possible danger of contamination during sample collection, sample preparation and the... 

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). 

Brief History. B.W., a 75-year-old woman, fell at home and experienced a sudden sharp pain in her left hip. She was unable to walk and was taken to a nearby hospital where x-ray examination showed an impacted fracture of the left hip. The patient was alert and oriented at the time of admission. She had a history of arteriosclerotic cardiovascular disease and diabetes mellitus, but her medical condition was stable. The patient was relatively obese, and a considerable amount of osteoarthritis was present in both hips. Two days after admission, a total hip arthroplasty was performed under general anesthesia. Meperidine (Demerol) was given intramuscularly as a preoperative sedative. General anesthesia was induced by intravenous administration of thiopental (Pentothal) and sustained by inhalation of halothane (Fluothane). The surgery was completed successfully, and physical therapy was initiated at the patient s bedside on the subsequent day. 

Lieberman JR, Hsu WK. Prevention of venous thromboembolic disease after total hip and knee arthroplasty. J Bone Joint SurgAm. 2005 87 2097-2112. 

Peichl P, Griesmacher A, Kumpan W, et al. Clinical outcome of salmon calcitonin nasal spray treatment in postmenopausal women after total hip arthroplasty. Gerontology. 2005 51 242-252. 

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. 

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