抄録
The clinical results were analysed using a new surface replacement type of elbow prosthesis made of alumina ceramics, both with an old type composed of a humeral mold (poliycystalline alumina) and an ulnar plate (HDP), and a recently developed new type replacing the ulnar plate with a ceramic peg (Fig.1) .
Twenty-three elbows of 19 rheumatoid arthritic patients were operated on with the ceramic prosthesis, and followed up for 36 months on an average (old type; 51 months, new type; 21 months) . Average age at operation was 53.1 years (32-72 years) . Two patients died during the follow-up time, and the other 17 patients were studied clinically and roentogenologically.
The criteria for operative indication for this prosthesis was painful contracture (flexion up to 100 degrees), painful instability due to joint surface destruction and ankylosis, but fairly good bone stock seen remaining on X-ray examinations.
In operative procedures the posterior approach modified from the Campbell method was made, and trimming of the humeral end was carried out by using a cutting guide (Fig.2) ; anterior angulation (30 degrees) of the humeral component was very essential for obtaining better flexion range and prosthetic fixation. In postoperative care, splintage was continued for over 6 weeks, but active ROM exercise was started at 3 weeks. Clinical evaluations were done by R. B. Brigham hospital scores and X-ray examinations were made every six months.
Postoperative assessment particularly showed sufficient pain relief and good stabillity. There was average post-operative improvement of 53 points in clinical score assessment; in the old type from 29.6 to 77.0 points, and in the new type from 20.5 to 78.6 points (Fig. 3) .The results were somewhat better in new type, because of development of operative technique and prosthetic design. In postoperative ROM, the average flexion/extension was 125/30 degrees and average pronation/supination was 35/38 degrees (Fig. 4) .Such improvement of flexion/extension was very advantangeous in daily life actirities such as face washing, hair dressing and eating, but the limited rotation disturbed management in hand work.
Some complications (Table 1) were experienced mainly due to early operative inskillfulness. Antero-posterior subdislocation was cured with a longer splintage and flexor muscle exercise, but slight lateral instability under 10 degrees was still observed. Olecranon fracture was fixed with wires at revision.
This ceramic elbow prosthesis is now used for limited cases but the clinical result was be very promising for the reconstruction of destructed rheumatoid elbows.
