Omarthrose ecentrée : symposium

Cuff tear arthropathy is defined as the combination of a gleno-humeral arthritis and a massive rotators cuff tear. It is generally admitted that the cuff tear, or its deficiency jeopardises the results of anatomic prosthesis. Grammont imagined and grew the concept of the reverse prosthesis whose aim was to remedy the insufficiency of the rotator cuff and whose use has dramatically modified the therapeutic approach in these complicated situations. The aim of this symposium is to analyse the results of shoulder arthroplasty (anatomic prosthesis, bipolar or reverse) in cuff tear arthropathy, in massive and isolated cuff tears which justify the use of prosthetic surgery, and in centered osteoarthritis with deficient cuff also justifying this use. Massive cuff tears and cuff tear arthropathy have been considered as the stages of a same pathology by Hamada whose classification has been used for the purposes of this study. Out of the 738 initial prosthesis, 111 have been eliminated because of death, incomplete files or lost of sight, without any known complication. Out of the remaining 627 who were used as a basis for this symposium (representing 85% of initial cases), 570 who still had their prosthesis were reviewed and their functional results analysed after 2 years or more. The population was mainly female (72%) who were injured on the dominant side (75%) with a mean age of 72 years. The preoperative Constant score was in average 24 and 24% of the patients had already been operated on their shoulder. For those who had an acetabulization of the acromion, the strength in external rotation was significantly less satisfying and the lesion of the infraspinatus and the teres minor were more frequent. 48 hemiarthroplasties, 52 bipolar and 527 reverse prosthesis were studied. At revision, with an average follow up of 52 months, the revision rate was 23% for hemiarthroplasties, 14% for reversed prosthesis and only 8% for bipolar prosthesis. The prosthesis was removed in 21% of hemiarthroplasties, 5% of reverse and 2% of bipolar. No infection to report in the hemi group or the bipolar group, whereas there was an infection rate of 5% in the reverse group. Nevertheless, the Constant score was significantly better with reverse (62) than with bipolar (45) or hemi (44). The active elevation was also better with the reverse whereas the external rotation was not as good as with anatomic prosthesis. The analytic study of the results of the reverse prosthesis shows a negative influence of the lesion of the sub-scapularis and the teres minor. The results are disappointing with young patients and those who had surgical precedents. On X-ray, we can notice 0.5% of humeral loosening withouth any correlation to the fact that the implant is cemented or not, 3.6% of glenoid loosening and 68% of scapular notches without any significant change on the Constant score. Their occurrence is correlated to a preoperative rising of the humeral head and a superior glenoid lesion. It is observed more frequently with the supero-lateral approach compared to the delto-pectoral one. The frequency of these notches grows with the follow up and their occurrence is often associated to humeral radiolucent lines. On the long term, the survival rate of these prosthesis is 89% at 10 years. The Constant score deteriorates gradually after 7 years; this seems to be linked to the occurrence of x-ray modifications in the years that followed. The main complications observed with reverse prosthesis were the infections (5.1%), the glenoid problems (5.1%), the instabilities (3.6%), the acromion fractures (3.0%). Infections can be treated by a wash out and antibiotics in the first 3 months, then the removal of the prosthesis becomes necessary. The instabilities occur more often for males, with delto-pectoral approach and with 36mm diameter glenoids. The glenoid problems are frequent in the first years and often due to technical errors or material defects (unscrewing of the glenosphere). Acromion fractures have an important clinical impact when they concern the spine and there healing is difficult to obtain, whichever method is used. In conclusion, the use of a prosthesis for cuff tear arthropathies must be thought about, especially in massive cuff tear without osteoarthritis, in patients with previous surgery, and in patients younger than 70. If the active elevation is conserved and the patient is young, the use of an hemi or a bipolar prosthesis can be debated. In other cases, the indication of a reverse prosthesis is preferable given that the clinical results are better. In these cases, the surgical technique must be accurate, bearing in mind the advantages and disadvantages of the two possible approaches, the type of implant (36 vs 42), the position and orientation of the glenoid baseplate according to the pre-operative bone wear, the orientation of the humeral implant, the need for reinsertion of the subscapularis and, maybe, the possibility of an associated transfer of the latissimus dorsi.