Mid-term survivorship results for a rotating-platform knee prosthesis.

Interest in mobile-bearing knee prostheses is increasing in the US market. We studied results at 2 to 5 years with a mobile-bearing system that includes a cobalt-chrome tibial tray and femoral component with a polyethylene cruciate-retaining tibial component insert that allows rotation around a central axis and can be used with cruciate-retaining or posterior-stabilized femoral components. The inserts used in this study were cruciate retaining and did not include the posterior-stabilized design. The goal of this study was to demonstrate the function and safety of this prosthesis along with the lack of spinout, which is a major concern in the mobile-bearing knee. Four hundred thirty-five knees constituted the study cohort and underwent survivorship analysis and complication reporting. Routine clinic evaluations included pre- and postoperative radiographs and Knee Society knee and function scores at 6 and 12 weeks and every 2 years. The most recent follow-up data within 2 to 5 years was included for the study along with survey data. Flexion at most recent follow-up averaged 125°. Knee Society score at most recent visit averaged 88 of 100. Knee Society function score averaged 83 of 100. Radiographic results were available for 226 knees, with 97.3% assessed as normal and 6 with these issues: patella stress fracture (3), aseptic tibial loosening (1), patellar osteolysis (1), and patella aseptic loosening (1). In comparison with the fixed-bearing knee equivalent, this mobile-bearing knee demonstrated at least equivalent results in terms of survivorship, function, and patient satisfaction in the short- and mid-term.

Leg length inequality in total hip arthroplasty.

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.

Modular femoral component for conversion of previous hip surgery in total hip arthroplasty.

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.

Training the scrub person on S-ROM technique total hip arthroplasty.

The role of the scrub person requires the following abilities: assessing situations immediately, carrying out correct actions, using critical thinking and good judgment, and communicating effectively with all members of the surgical team. The scrub person greatly contributes to the success of total joint replacement surgery. He or she must understand the instrumentation, sizes, trials that are required, and proposed procedural steps to prepare the femur and acetabulum for implantation. A knowledgeable, competent scrub person enhances the flow of surgery and helps keep the time of the procedure to a minimum.

Posterior-lateral approach to minimal incision total hip arthroplasty.

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.