A custom-made guide-wire positioning device for Hip Surface Replacement Arthroplasty: description and first results

<p>Abstract</p> <p>Background</p> <p>Hip surface replacement arthroplasty (SRA) can be an alternative for total hip arthroplasty. The short and long-term outcome of hip surface replacement arthroplasty mainly relies on the optimal size and position of the femoral component. This can be defined before surgery with pre-operative templating. Reproducing the optimal, templated femoral implant position during surgery relies on guide wire positioning devices in combination with visual inspection and experience of the surgeon. Another method of transferring the templated position into surgery is by navigation or Computer Assisted Surgery (CAS). Though CAS is documented to increase accurate placement particularly in case of normal hip anatomy, it requires bulky equipment that is not readily available in each centre.</p> <p>Methods</p> <p>A custom made neck jig device is presented as well as the results of a pilot study.</p> <p>The device is produced based on data pre-operatively acquired with CT-scan. The position of the guide wire is chosen as the anatomical axis of the femoral neck. Adjustments to the design of the jig are made based on the orthopedic surgeon's recommendations for the drill direction. The SRA jig is designed as a slightly more-than-hemispherical cage to fit the anterior part of the femoral head. The cage is connected to an anterior neck support. Four knifes are attached on the central arch of the cage. A drill guide cylinder is attached to the cage, thus allowing guide wire positioning as pre-operatively planned.</p> <p>Custom made devices were tested in 5 patients scheduled for total hip arthroplasty. The orthopedic surgeons reported the practical aspects of the use of the neck-jig device. The retrieved femoral heads were analyzed to assess the achieved drill place in mm deviation from the predefined location and orientation compared to the predefined orientation.</p> <p>Results</p> <p>The orthopedic surgeons rated the passive stability, full contact with neck portion of the jig and knife contact with femoral head, positive. There were no guide failures. The jig unique position and the number of steps required to put the guide in place were rated 1, while the complexity to put the guide into place was rated 1-2. In all five cases the guide wire was accurately positioned. Maximum angular deviation was 2.9° and maximum distance between insertion points was 2.1 mm.</p> <p>Conclusions</p> <p>Pilot testing of a custom made jig for use during SRA indicated that the device was (1) successfully applied and user friendly and (2) allowed for accurate guide wire placement according to the preoperative plan.</p

Technical pearls in total hip arthroplasty

Total hip arthroplasty (THA) has had a big impact on the quality of life of millions of patients. Primary THA has a very high success rate and implant survival time of more than 30 years have been reported. However, because of the high number of procedures performed, the small percentage of patients requiring a revision surgery still represent a large number of patients. Templating by means of radiography of hip joints with a defectuous implant-bone fixation can be hindered by the presence of cement and/or by reduced bone quality. Selection of the implant should be guided by the altered anatomy of the femur and/or acetabulum. In some cases the commercially available implants do not allow fixation and restoration of the joint mechanics. To adapt the implants to the patient's anatomy custom production can be envisioned. Custom made stem implants have been used since 1987 in our centre. Adaptations have been made and tests for evaluating implant stability have been evaluated. Also a new technique that has the objective to help the surgeon in determing the correct stem insertion during surgery has shown promissing results. Several changes in design of the acetabular component have progressively improved the cup stability, even in revision surgery. But a small number of patients present with pelvic and acetabular bone defects that cannot be bridged by the standard cup implants. Also custom made acetabular implants are progressively been used and the new production techniques offer promissing perspective

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