Clinical correlation of femoral component migration in hip resurfacing arthroplasty analyzed by Einzel-Bild-Röntgen-analyze-femoral component analysis

Towards the First Generation of Biomimetic Fixation for Resurfacing Arthroplasty Endoprostheses

This paper presents advances in designs of resurfacing arthroplasty endoprostheses that occurred through their historical generations. The critical characteristics of contemporary generation hip resurfacing arthroplasty endoprostheses are given and the failures resulting from the specific generation cemented and short stem fixation of the femoral component are reviewed. On the background of these failures, the critical need arises for an alternative approach to the fixation of components of resurfacing arthroplasty leading towards the first generation of biomimetic fixation for resurfacing arthroplasty endoprostheses. The state of the art of the completed bioengineering research on the first biomimetic fixation for resurfacing arthroplasty endoprostheses is presented. This new design type of completely cementless and stemless resurfacing arthroplasty endoprostheses of the hip joint (and other joints), where endoprosthesis components are embedded in the surrounding bone via the prototype biomimetic multi-spiked connecting scaffold (MSC-Scaffold), initiates the first at all generations of biomimetic endoprostheses of diarthrodial joints.

Migration pattern of a cobalt-chrome monoblock acetabular component after metal-on-metal hip resurfacing

OBJECTIVES

The purpose of this study was to study the initial fixation and migration pattern of a monoblock acetabular component used for a metal on metal hip resurfacing using Einzel Bild Roentgen Analyse (EBRA).

METHODS

99 patients with a mean age of 49.6 years (range 28.5-66.3 years) of whom 14 were bilateral underwent a hip resurfacing (Conserve Plus®, MicroPort, Memphis, TN) for a total of 113 resurfacings. Acetabular component orientation was noted with 35 of the 113 components (31.0%) having a lucency >2 mm on the immediate postoperative radiograph.

RESULTS

The mean follow-up for our cohort of 113 hips is 50 months (2-79 months). When examining the 2-year migration mark, 37 of the 113 hips exceeded the threshold of 0.5 mm/year with a median total migration of 1.40 mm (range 1.02-4.24). 6 resurfacings underwent revision surgery for aseptic loosening of the acetabular component at a mean time of 43.6 months. Presence of initial lucency (OR 2.29, p = 0.05) was the only significant predictor of migration over threshold at 2-years. Those that had migrated over the threshold (1.0 mm) at 2 years were at significantly greater risk of continued migration at 4 years.

CONCLUSIONS

The migration pattern of this component raises concerns about long term performance, with postoperative lucencies representing a significant factor for future migration.

The thermal effects of lavage on 57 ox femoral heads prepared for hip resurfacing arthroplasty

BACKGROUND AND PURPOSE

Previously, we have documented surface temperatures recorded by thermography great enough to cause osteonecrosis of the femoral head during hip resurfacing. We now performed an in vitro investigation with 3 questions: (1) whether water irrigation reduced bone surface temperature, (2) whether external bone temperatures were similar to core temperatures, and (3) whether blunting of the reamer affected temperature generation.

METHODS

Using an ox-bone model, 57 femoral heads were peripherally reamed. The surface temperatures of bone were measured using a thermal camera and internal bone temperatures were measured using 2 theromocouples. We measured the effects of cooling with water at room temperature and with ice-cooled water. Progressive blunting of reamers was assessed over the 57 experiments.

RESULTS

Mean and maximum temperatures generated during peripheral reaming were greater when no irrigation was used. Ice-cold saline protected femoral heads from thermal damage. External bone temperatures were much greater than internal temperatures, which were not sufficiently elevated to cause osteonecrosis regardless of lavage. Blunting of the reamer was not found to have a statistically significant effect in this study.

INTERPRETATION

Cooling with ice-cooled water is recommended. Internal bone temperatures are not elevated despite the high surface temperatures reached during femoral head resurfacing.

Long-term results with the Wagner metal-on-metal hip resurfacing prosthesis

The purpose of this study was to report the long-term results of the metal-on-metal Wagner resurfacing prosthesis. Between January 1991 and August 2004, 54 Wagner resurfacing prostheses were implanted in 52 patients. There were 45 female patients (1 bilateral case) and 7 male patients (1 bilateral case). All the operative procedures were performed using the anterior approach. Of those cases available, the average time to follow-up was nine years. The average Merle dAubign score improved from 8.3 preoperatively to 17.3 postoperatively (p-value < 0.001). Seventeen prostheses required revision. Radiographic evidence of femoral neck narrowing was seen in three prostheses that remained in situ. Combined with a stricter diagnosis and an exact operating technique, the Wagner metal-on-metal surface replacement of the hip joint may offer an alternative surface replacement option.