Introduction and background
While the benefits of total hip replacements are numerous, there is a known incidence of associated pain leading to early revision. Have attempts at improving the prosthetic implant, shortened lengths of hospital stay, minimally invasive procedures and metal on metal bearings been a process of revolution or as in the case of Gulliver, devolution?
The goal of the surgeon has historically been pain relief and a 20-year plus satisfactory outcome when performing a total hip. More recently, survivorship prioritization seems to have been replaced by restoration of hip anatomical geometry, thereby optimizing muscle tension and strength, equalization of leg lengths, and enhancement of hip stability all via modularity. The newer generations of prostheses have been designed in an attempt to facilitate and accommodate the latest fads in surgical approaches so as to lessen the scar length, perhaps minimize muscle damage-still a matter of debate-and return the patient to full activity status in days or weeks rather than months.
I just received an AMA alert that by 2030, 42% of Americans will be obese. Short incision, less hospital stay, prompt return to activity, who are we kidding? Lets look more closely at the cost of supposed progress in the newest prosthetic designs.
Metal Fretting and Corrosion. This has been reported with cobalt chrome and cobalt chrome- titanium junctions. The more modularity and junctions between metals, the more potential metal debris generation. Metal on metal bearings produce small metallic wear debris. Furthermore, elevated blood serum ion levels and metal hypersensitivity resulting in an adverse local tissue reaction may occur with metal-metal articulate surface bearings causing premature failure due to osteolysis, aseptic loosening and pseudo tumor formation.
So what should you do and look for whether or not you are in pain after a total hip replacement?
Evaluation for infection-a screening serum ESR, C-Reactive Protein, and WBC. If any of these are abnormal, a hip aspiration need be performed.
Serum metal ion levels-serum chromium ion levels above 17ug/L and cobalt ion levels above 19ug/L suggest metallosis within the joint. Pseudotumors have been found at lower levels and are identified by ultrasound and CT scans. In the United Kingdom, the cut off level is 7 parts per billion (7ppb) chromium or cobalt.
Metal hypersensitivity-Nickel is the worst offender but chromium and cobalt may play a role. The problem is the area is still poorly understood with the only available testing including patch testing and the lymphocyte transformation test.
Radiographic analysis-Your physician will look for signs of loosening, osteolysis and pseudotumor formation
If you have a painful total hip replacement, you need an evaluation.
There is another consideration, postpone or avoid the replacement. Might Regenerative medicine and stem cell management, help control you pain and possibly postpone or even help avoid a total joint replacement?
Mitchell B. Sheinkop, M.D.
312-475-1893 or 312-475-1893
1565 N. LaSalle Street
Chicago, Illinois 60610