Michael Solomon

Metal Sensitivity as a Cause of Groin Pain in Metal-on-Metal Hip Resurfacing

We describe 4 patients pooled from our patient populations who presented with groin pain at different periods postoperatively after implantation of a metal-on-metal hip resurfacing. Each patient underwent exploratory surgery after radiographic imaging, hematologic testing, and microbiological assessment of joint aspirations failed to explain their symptoms. Samples of periprosthetic tissues revealed extensive amounts of lymphocytic infiltrates that were suggestive of an immunologic reaction. The patients obtained complete resolution of symptoms subsequent to revision surgery. The incidence of implant failures resulting from metal sensitivity is unknown owing to the difficulty in making a confirmed diagnosis. The possibility that this is the source of groin pain should be considered when other reasons for symptoms of pain and/or joint effusion in hips with metal-on-metal resurfacing arthroplasties have been discounted.

Fracture and loosening of Charnley femoral stems. Comparison between first-generation and subsequent designs

We report the results of a 4- to 17-year clinical and radiological follow-up of 264 Charnley first-generation stems in comparison with those of 402 second- and subsequent-generation stems. The incidence of fracture was 4.1% in first-generation stems and 0.5% in second- and subsequent-generation stems. The incidence of stem loosening requiring or likely to require revision was 3.1% in first-generation and 11.4% in second-generation stems. We believe that the increased loosening rate in second- and subsequent-generation stems is due to their larger cross-sectional area, which produces an increase in flexural stiffness.

Survivorship of cemented total hip arthroplasty in patients 50 years of age or younger.

One hundred fifty-six Charnley low-friction arthroplasties performed in patients 50 years of age or younger are reviewed. Excluding sepsis, survivorship analysis showed a 12% probability of mechanical failure at 10 years. The detailed clinical and radiological results of 130 hips with a 3-16-year follow-up period are presented. Revision surgery was required in 14 hips (10.8%), for the following reasons: sepsis (2.3%), loose sockets (2.3%), loose stems (5.4%), and stem fracture (0.8%). Evidence of radiological loosening indicative of pending failure was present in 14 hips (12.0%). At 10 years the predicted failure rate of the surviving hips was 12%.

Total hip arthroplasty complicated by a malignant fibrous histiocytoma: A case report

Tumors associated with total hip arthroplasty are uncommon. The authors report the eighth case of a malignant fibrous histiocytoma associated with a total joint arthroplasty and discuss its etiology and significance.

Variation in functional pelvic tilt in patients undergoing total hip arthroplasty

Aims The pelvis rotates in the sagittal plane during daily activities. These rotations have a direct effect on the functional orientation of the acetabulum. The aim of this study was to quantify changes in pelvic tilt between different functional positions. Patients and Methods Pre‐operatively, pelvic tilt was measured in 1517 patients undergoing total hip arthroplasty (THA) in three functional positions ‐ supine, standing and flexed seated (the moment when patients initiate rising from a seated position). Supine pelvic tilt was measured from CT scans, standing and flexed seated pelvic tilts were measured from standardised lateral radiographs. Anterior pelvic tilt was assigned a positive value. Results The mean pelvic tilt was 4.2° (‐20.5° to 24.5°), ‐1.3° (‐30.2° to 27.9°) and 0.6° (‐42.0° to 41.3°) in the three positions, respectively. The mean sagittal pelvic rotation from supine to standing was ‐5.5° (‐21.8° to 8.4°), from supine to flexed seated was ‐3.7° (‐48.3° to 38.6°) and from standing to flexed seated was 1.8° (‐51.8° to 39.5°). In 259 patients (17%), the extent of sagittal pelvic rotation could lead to functional malorientation of the acetabular component. Factoring in an intra‐operative delivery error of ± 5° extends this risk to 51% of patients. Conclusion Planning and measurement of the intended position of the acetabular component in the supine position may fail to predict clinically significant changes in its orientation during functional activities, as a consequence of individual pelvic kinematics. Optimal orientation is patient‐specific and requires an evaluation of functional pelvic tilt pre‐operatively.

The flying buttress acetabular bone-graft.

Primary total hip arthroplasty is often required in the end-stage osteoarthritic hip secondary to hip dysplasia. At the time of surgery, a decision is made whether to bone-graft the dysplastic acetabulum to accommodate the acetabular component. A technique is described to augment the acetabular bone stock by adding a flying buttress autograft to the structural shelf graft.

A TECHNIQUE OF REVISION OF FAILED ACETABULAR COMPONENTS LEAVING THE FEMORAL COMPONENT IN SITU

Management of a failed acetabular prosthesis in the presence of a well-fixed femoral prosthesis poses a technical challenge in revision joint arthroplasty. While failures can occur at any age during the lifetime of a prosthesis, a pattern has emerged of earlier failure of the femoral component and later failure of the acetabular component. The authors describe a technique in which the stable femoral prosthesis is left in situ during acetabular revision. The advantages of this technique include excellent exposure of the acetabulum, reduction in operative time and intraoperative morbidity, as well as early postoperative mobilization.