Biomedical subjects
Publications and source records attributed to Wayne M Goldstein.
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We studied the P.F.C. Sigma rotating-platform total knee arthroplasties performed during 2004 and 2005 to assess implant size variations in men versus women and size variation in bilateral knees. We subsequently studied commercial femoral radiograph templates to compare mediolateral and anteroposterior dimensions. Sixty-four percent of women more frequently had a tibial tray one size smaller with respect to the femur and 63.5% of men had the same-sized femur and tibia. Bilateral knees were the same size in both sides 97% of the time in women, and 90% in men. The template comparison found that the P.F.C. Sigma rotating-platform femur had a mediolateral dimension that was smaller than many knee replacements commercially available.
We describe experience with 2000 cruciate-retaining Sigma RP total knee arthroplasties performed between September 2000 to January 2006. All procedures were performed with a midvastus arthrotomy, medioposterior release, and posterior condylar clean-out technique. This implant design uses a congruent polyethylene bearing to diminish contact stress while allowing rotation between the polyethylene bearing surface and tibial tray. Of the 2000 knees, 1596 had follow-up data at one year. Seven hundred-twenty-seven had an average flexion of 123 degrees, 692 had an average Knee Society Score of 94, and 672 had an average function score of 86.
Postoperative leg length inequality after total hip arthroplasty frequently leads to medical liability issues because no standard exists regarding the acceptable disparity. Modular stems allow control of offset, independent sizing of the distal femoral anatomy, as well as proximal medullary sizing. The authors compared the restoration of leg length in two cohort protocols. In the 2001 cohort, tapered stems were exclusively used, giving priority to fit and fill of the medullary canal. In the 2004 cohort, porous-tapered stems, or an S-ROM modular stem (DePuy Orthopaedics Inc., Warsaw, Ind) when needed, were used based on preoperative templating to restore the center of femoral head rotation. Prior to and after surgery, length from center measurements were taken (center of rotation of the femoral head to the top of the lesser trochanter) and the vertical vector to compare the difference in actual leg length. In the 2001 cohort, the mean increase of length from center was 9 mm (7 mm leg length). In the 2004 cohort, 25% of the hips were inappropriate for tapered stems. S-ROMs were used because a tapered stem would lengthen the leg. In the standard offset tapered stem, the mean increase of length from center was 6 mm (4 mm leg length). In the high offset tapered stem, the mean increase of length from center was 7 mm (5 mm leg length). In the S-ROM stem with varying offsets, the mean increase of length from center was 6 mm (4 mm leg length). Only the S-ROM consistently avoids overlengthening in the majority of patients.
The conversion of previous hip surgery to total hip arthroplasty creates a durable construct that is anatomically accurate. Most femoral components with either cemented or cementless design have a fixed tapered proximal shape. The proximal femoral anatomy is changed due to previous hip surgery for fixation of an intertrochanteric hip fracture, proximal femoral osteotomy, or a fibular allograft for avascular necrosis. The modular S-ROM (DePuy Orthopaedics Inc., Warsaw, Ind) hip stem accommodates these issues and independently prepares the proximal and distal portion of the femur. In preparation and implantation, the S-ROM hip stem creates less hoop stresses on potentially fragile stress risers from screws and thin bone. The S-ROM hip stem also prepares a previously distorted anatomy by milling through cortical bone that can occlude the femoral medullar canals and recreate proper femoral anteversion and reduces the risk of intraoperative or postoperative periprosthetic fracture due to the flexible titanium-slotted stem. The S-ROM femoral stem is recommended for challenging total hip reconstructions.
As surgeons learn to perform minimally invasive hip arthroplasty procedures, the various techniques will evolve and one or two approaches may eventually become the standard. Currently, most of these procedures are reserved for the nonmorbidly obese patients; however, as techniques are perfected and surgeons gain experience, this patient population may eventually be served. Surgeons must present information to patients in a responsible manner and clarify the actual versus perceived advantages of the MITH. It is unfortunate that some patients may abandon an experienced surgeon (who will likely give an excellent long-term clinical outcome) for an inexperienced surgeon who can provide a smaller incision (with long-term benefits thus far unknown). Surgeons must also address the same comorbidities and complications for MITH arthroplasty as with the conventional approaches such as DVT, fat embolism, pain control, and wound healing. Routines for postoperative care and screening for complications must remain within the plan of care for the standard incision and MITH patient.information to patients in a responsible manner and clarify the actual versus perceived advantages of the MITH. It is unfortunate that some patients may abandon an experienced surgeon (who will likely give an excellent long-term clinical outcome) for an inexperienced surgeon who can provide a smaller incision (with long-term benefits thus far unknown). Surgeons must also address the same comorbidities and complications for MITH arthroplasty as with the conventional approaches such as DVT, fat embolism, pain control, and wound healing. Routines for postoperative care and screening for complications must remain within the plan of care for the standard incision and MITH patient.
TOTAL HIP ARTHROPLASTY (THA) has been proven to decrease a patient's pain and improve function and quality of life. This procedure has been performed in the United States since 1960. Follow-up data suggest long-term success with a decreasing rate of complications and low rate of revision. MORE THAN 168,000 THA procedures are performed in the United States every year. There is an 80% chance these hip replacements will last at least 20 years. CURRENT IMPROVEMENTS in hip designs, surgical techniques, fixation methods, prophylactic therapies, preadmission education, and rehabilitation have contributed to improved patient outcomes.
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