HIP International

In the great majority of the cases the “Anteversion Angle” (AVA) is in the normal range (10-20°) and on insertion the femoral stem follows automatically the direction of the femoral neck. There are basically 5 means of correcting an increased AVA: 1) The smaller the diameter of the endoprosthetic stem and the more its cross-section is circular the easier it is to modify the rotational position. 2) The lower the resection of the femoral neck the greater the freedom of correction of the anteversion. 3) A custom-made femoral endoprosthesis. 4) A non-cemented endoprosthesis with a stem circular in cross section - such as the conical stem of Wagner - can easily be positioned in a great variety of rotational positions. 5) To correct an AVA of the femur of more than 45 degrees an inter- or sub-trochanteric derotational osteotomy of the femur is indicated. With this not only is the AVA corrected but also the greater trochanter is brought from its posterior position to a more lateral one and the functional lever arm of the abductors is lengthened. To stabilize the osteotomy the use of a femoral endo-prosthesis with a non-cemented stem which is stable in rotation all along its length is recommended.

A new non-invasive screener for the detection of proximal deep vein thrombosis was evaluated in two consecutive series of patients undergoing primary total hip replacement. The system, which utilises computerised strain gauge venous occlusion plethysmography, was simple to use and allowed serial screening of large numbers of patients without complication. Comparison with venography in 112 patients gave a specificity of 96% (106/110) and a sensitivity of 100% (2/2) for clinically important proximal DVT.

Based on this study, a larger management study was performed. After total hip replacement, 516 patients were serially screened and all were followed to at least four months (mean 7.6 months) from surgery. Venography was only requested after a positive screening test. The screener correctly identified proximal and major calf thrombi in this group allowing early treatment. There were no fatal pulmonary emboli.

This initial assessment suggests that computerised strain gauge plethysmography may be useful in identifying those patients with silent venous thrombosis after total replacement.

We report a retrospective study of the incidence of major complications following Charnley-Hastings bipolar hemiarthroplasty in 117 patients with 120 fractures of the femoral neck. Primary hemiarthroplasty (n=40) was used for irreducible or old fractures and secondary hemiarthroplasty (n=80) for fractures with disturbed healing. The mean age was 80 (54-95) years. The mean follow-up was 34 (0-149) months. There was no major complication in 87.2 percent. Mortality was 10.3 percent after 6 months and 13.7 percent after one year. Dislocation occurred in 7.5 percent, prosthetic loosening in 4.2 percent, acetabular fracture and deep infection in 0.8 percent respectively. Reoperation was required in 7.5 percent: open reduction after dislocation (2.5 percent), conversion to a Charnley total hip arthroplasty (3.3 percent), Girdlestone arthroplasty (0.8 percent) and exchange of a loose femoral component (0.8 percent). We conclude that the selective use of bipolar hemiarthroplasty for fractures of the femoral neck carries few major complications. Patient selection must be strict in order to reduce the risk of dislocation.

A variety of instruments and techniques have been developed to facilitate cement removal in THA revisions. Many of these methods can lead to femoral fractures or uncontrolled cortical perforation, increasing bone damage. The purpose of this brief report is to present a new device that particularly facilitates the extraction of the cement plug from the femoral canal. The basic characteristic of this system is to guide different specific tools, with a high reliability, through the middle of the cement plug. In our experience, this device has always permitted femoral cement extraction without serious complications.

Fractures of the femoral head are not frequent and are almost always combined with dislocation of the hip. We reviewed 43 cases of femoral head fractures (33 men, 10 women), mean age 38.6 years. Using Pipkin's classification there were 13 type 1 cases, 5 type 2 and 25 type 4. Twenty-nine patients (67.4%) were seen again after a minimum of two years. Overall, there were ten excellent results, nine good, four fair and six poor. Complications were three cases of ischemic necrosis, eleven secondary arthritis, and three cases of heterotopic ossification.

CT is an extremely useful method for assessing these lesions, especially in cases with small intra-articular fragments (Pipkin 1 and 4). Therapeutic indications obtained from this study were a non-invasive approach for Pipkin type 1 lesions, except those with a large intra-articular fragment, surgery for Pipkin type 2 cases, with osteosynthesis of the fragments, mainly using Herbert screws, and surgery particularly for Pipkin type 4, especially for osteosynthesis of the fragments of acetabular wall.

Aseptic loosening is the major cause of failure in primary total hip replacements. Loss of bone stock occurs in both cementless and cemented implants. Impaction of morsellised allograft represents a major advance in the restoration of bone loss at revision hip surgery. This study was designed to test the early stability of the femoral impaction construct. Polished double tapered stems were inserted into neomedullary canals within impacted allograft in fibreglass femora. Subsidence was measured during cyclical loading. Four methods of impaction grafting were tested: allograft alone; allograft and heparinised blood; allograft/cement/heparinised blood; allograft/cement/clotted blood.

Uncemented impaction grafting failed at low loads and few cycles. The cemented technique supported higher loads. Heparinised blood reduced the strength of the composite. Initial stability was achieved with allograft, cement and clotted blood. There is need for caution in the early post-operative period due to the wide variation in initial stability of the allograft composite. The reliability of this technique has been increased by the use of specialised instruments. Experimental studies and clinical experience suggest that this approach to revision surgery is technique dependent.

Total hip replacement is one alternative in the management of refractory coxarthrosis in patients with cerebral palsy. There are however concerns regarding both loosening and dislocation especially in the athetoid variant. We report two successful cases of total hip replacement in athetoid cerebral palsy and conclude that total hip replacement offers the only real chance of improving the patient's symptoms while at the same time maintaining or improving mobility in this group.