Evolution of surgical techniques for the treatment of angular and torsional deviation in DDH: 20 years experience.

The anatomical abnormalities associated with developmental dysplasia of the hip (DDH) increase the complexity of hip arthroplasty. In addition, previous femoral osteotomy can deform the proximal femur. Noncemented cups and stems are specifically designed for dysplasia to recover the true acetabular region in Crowe grade IV and sometimes Crowe grade III; additional surgical procedures are required. The purpose of the study was to analyse the surgical procedure and then the reconstructive options in DDH. From 1984 until now, total arthroplasty has been performed, on dysplastic hips, in 2,101 patients for 2,308 hips (207 patients bilateral 9% rate). All the procedures were performed by the senior authors (LS, GG) at the same hospital specialised in elective hip surgery. More than 80% of patients came from Northern Italy. The average age was 51 (range 32-83), 565 cases had involved a previous femoral osteotomy. Out of these 2,308 cases, 128 cases needed treatment for corrections of femoral side deformity; 64 cases were subjected to a greater trochanter osteotomy. In 12 cases, proximal femur shortening was involved. In 9 cases, rotational abnormality and shortening were controlled with a distal femur osteotomy. Fifty-five cases were treated by a shortening subtrochanteric osteotomy that allows corrections of any deformity. Only noncemented stems were used. Long-term results in these patients are consistently inferior (70% survival rate at 15 years) compared to those in the non-DDH population (97.7% survival at 15 years). On the femoral side, early failures are the reflection of a learning curve and are due to insufficient fixation of the osteotomy. The more promising outcomes are those involving a shortening subtrochanteric osteotomy.

First implant acetabular components: historical aspects, a comparison of models and a review of the literature.

The article describes the features of the most commonly-used acetabular components in first implants in light of development in construction as regards intrinsic features, materials used, biological behavior, and design. The following versions are examined: screwable cone-shaped trunk, cemented polyethylene, cemented metal-back, HA-coated press-fit, expansion, dysplastic hip, and anti-dislocating components. The screwable cone-shaped trunk acetabular component takes hold in the acetabular bone through torsion and compression, and threading provides greater stability as compared to equivalent models that have wings or screws. Cemented polyethylene acetabular components are characterized by low costs and good results, on the condition that some specific parameters are respected (the presence of a dry bone bed, pressurization of the cement, use in elderly patients who do very little physical activity). Cemented metal-back acetabular components have features similar to polyethylene components, from which they differ because of the possibility of being able to substitute the internal polyethylene component without having to revision the entire acetabulum. HA-coated press-fit components have solved the problems encountered in cemented versions, such as loosening and the generation of polyethylene particulate, at the same time obtaining excellent osteo-integration. The expansion cup self-stabilizes thanks to a memory effect due to the contraction-relaxation mechanism with which it is lodged, adapting to the micro-movements of the acetabulum. Components used in the dysplastic hip are particular versions with a reduced diameter that have specific hooks that provide stabilization, capable of settling in the pathologic bone with minimum reaming of the same. Anti-dislocation cups are special models that have bipolar inserts or a ring (plastic or metal) that blocks the head in the prosthetic acetabulum, obstructing its dislocation.

Primary total hip arthroplasty using a grit-blasted, press-fit femoral prosthesis.Long-term results with survivorship analysis.

BACKGROUND: This report presents the initial experience with the use of a grit-blasted, press-fit femoral prosthesis. METHODS: The first 300 consecutive primary total hip arthroplasty procedures using a collarless, three-dimensional tapered, straight, titanium alloy stem with a grit-blasted surface (performed in 299 patients) were evaluated with independent clinical and radiographic follow-up examinations up to sixteen years. Eight different types of acetabular components, including a cementless all-polyethylene socket in 80 percent of the cases, were used. Radiographic evaluation, performed by an independent observer using a zonal analysis method, included assessment of component migration, Enghs implant-bone femoral fixation score, implant-bone demarcations, and periprosthetic osteolysis. The average duration of long-term radiographic follow-up was 12.6 years (range; 10 to 16 years). RESULTS: At last examination only five hips were lost to follow-up and 69 patients were deceased. The overall mechanical failure rate (i.e. unstable with or without revision) of the femoral component was 2 percent. The femoral revision rate was 7 percent (two hips for aseptic loosening, five hips for septic loosening, and twelve hips with osseointegrated stems for severe progressive femoral osteolysis) and the acetabular revision rate was 27 percent (revised for either socket migration or progressive peri-acetabular osteolysis or both). Survivorship, based on any revision (femoral or acetabular) was 89 percent at ten years and 62 percent at fourteen years; survivorship of the femoral component was 95 percent at ten years and 90 percent at fourteen years. The incidence of femoral periprosthetic osteolysis, by radiographic examination at ten years or more was 47 percent, including 12 hips (5 percent) with distal endosteal osteolysis. Femoral implant-bone fixation was stable, bone-ongrowth in 97 percent; stable, fibrous-fixation in 1 percent, and unstable, fibrous-fixation in 2 percent of the cases. CONCLUSIONS: The grit-blasted, press-fit, collarless, tapered femoral component continued to per-form well clinically and radiographically up to sixteen years of follow-up despite the challenging environment of periprosthetic osteolysis associated with the acetabular component design. The high incidence of failure among the cementless all-polyethylene sockets was not unexpected and the use of this acetabular implant was discontinued in 1985. While considered a "first-generation" cementless stem, this implant is still in use virtually without design modifications. This study demonstrates the durability of the results of the grit-blasted femoral component and indicates that such an implant offers a viable alternative for fixation without bone cement. (Hip International 2002; 2: 55-72).

The CLS system. Theoretical concept and results.

The CLS femoral prosthesis is a titanium stem designed as a 3-dimensional taper for press-fit implantation. The distal part of the prosthesis is intentionally made small so that it will not fill the intramedullary canal in the proximal diaphysis. The surface is bead blasted and has no bone ingrowth surface. Ribs in the proximal part of the prosthesis are designed to minimize rotational migration. The CLS acetabular component is a 6-sided expanding cup intended for implant with press-fit stabilization. This article emphasizes indications for use of the CLS, and it includes a brief report on clinical and radiographical results. Data from a review of the first 300 CLS stems implanted from 1983 to 1985 with an 82-month average follow-up suggested that neither bone ingrowth nor distal fit and fill are necessary for stable secondary fixation of an uncemented stem.

[Personal experiences with uncemented prostheses]. / Unsere Erfahrungen mit nicht-zementierten Prothesen.

Experience with different types of non-cemented total hip endoprostheses is critically discussed. Three radiological criteria of a good result indicated: the presence of radiolucent lines, cancellous transformation, and a particular appearance and thickness of the cortex. The radiological changes and clinical results make it possible to draw a 'survival curve' for each type of implant. This series shows that unsatisfactory results have been due mostly to primary diaphyseal, distal fixation of the prosthetic stem. The CLS prosthesis, with mainly metaphyseal primary anchorage, is presented. Discussion of the radiologically and histologically established response of bone.