| Complications of Shoulder Arthroplasty: How To Avoid and How to Treat (P) - Index

VIII. Notching of the Scapula After Reverse Arthroplasty. A Concern?

G. Walch, MD, Ch. Lévigne, MD, A. Young, MD

Classification

Scapular notching has been classified into 5 grades by Sirveaux and Nerot: Grade 0 = No notch; Grade 1 = the defect concerns only the pillar; Grade 2 = contact with the lower screw of the baseplate; Grade 3 = extension over the lower screw; and Grade 4 = extension reaches the central peg (15).

Pathogenesis and Progression

Notching has been recognized as a consequence of a mechanical impingement between the humeral part and the lateral pillar of the scapula (2,3,15). Chemical osteolysis could be associated because of PE wear debris as a consequence of this mechanical impingement. Progression is controversial: some authors have reported that it appears during the first year and then stabilizes (14); whereas for others the frequency and the severity of notching have been observed to increase with time (11).

Clinical consequence

None has been reported regarding pain, Constant score and range of motion in most of the publications (9,10). Sirveaux et al were the only group to report a significant clinical influence (16).

How to avoid it

— Glenoid height: the base plate must be implanted low enough to have the sphere overhanging the inferior part of the scapula (13,14). Kelly et al proposed the 12mm rule with the Grammont type prosthesis in order to anticipate the obliquity of the scapula lateral pillar and the reaming (7).

— Tilt of the sphere: Inferior tilt of the sphere prevents contact between humerus and scapula in adduction. Some authors (13,14)) do not recognize a biomechanical or clinical influence of inferior tilt. Although inferior positioning is the most important factor, inferior tilting may help to prevent notching, moreover inferior tilting helps to prevent at any cost superior tilting which is always detrimental for notching and baseplate stability (12).

— Lateralization of the sphere: The lateralization may be part of the sphere design (5,8) or related to bone graft (1). It seems that the frequency of notching decreases with the amount of lateralization. Excessive lateralization may cause glenoid loosening due to the lever arm on the glenoid anchorage.

— Eccentric spheres are another option to lower the position of the sphere and clear the lateral scapular pillar (6).

— Decreased inclination angle: with 155° inclination of the humeral cup, the Grammont type design increases the potential for contact between the humerus and scapula. A lower inclination angle significantly decreases this risk (6,8) but increases the risk of prosthetic instability.

— Deltopectoral approach: This approach allows better exposure of the inferior part of the glenoid to satisfactorily position the baseplate. It is recognized that it is more difficult to implant the baseplate inferiorly with downward tilt using a superolateral approach (10,11).

— Preoperative superior erosion of the glenoid: The preoperative type of the glenoid erosion (types E2 and E3 according to Favard (4)) influences surgical positioning of the baseplate(12). Spontaneous upward rotation of the scapula in the coronal plane has also been recognized as a risk factor for notching because of the resulting inappropriate superior tilt of the glenoid side.

— Larger glenosphere (42mm diameter): Guttierez et all showed in a computerized model that increased glenosphere diameter resulted in greater “impingement free” range of motion (6).

— Surgeon Experience: Rather than trying to solve the problem with one major effect (lateralization, inclination, glenoid height...) it is probably better (and less risky) to use a little bit of everything, i.e. 3 to 4 mm lateralization, 3 to 4 mm inferior overhanging, 10° inferior tilt, 145° inclination angle...

Conclusion

Although no definite relationship has been established between scapular notching and glenoid loosening in Reverse Shoulder Arthroplasty, and notching does not influence the long term follow-up (>10 years) of the reverse prosthesis, notching has been recognized as a disturbing and worrying radiological sign.


References

1. Boileau P, Watkinson DJ, Hatzidakis AM, Balg F. Grammont reverse prosthesis: design, rationale, and biomechanics. J Shoulder Elbow Surg 2005;14(1 suppl S):147S-61S.

2. Delloye C, Joris D, Colette A, Eudier A, Dubuc JE. Complications mécaniques de la prothèse totale inverse de l’épaule. Rev Chir Orthop 2002;88:410-4.

3. De Wilde L, Mombert M, Van Petegem P, Verdonk R. Revision of shoulder replacement with a reversed shoulder prosthesis (Delta III): report of five cases. Acta Orthop Belg 2001;67:348-53.

4. Favard L, Lautmann S, Sirveaux F, Oudet D, Kerjean Y, Huguet D. Hemiarthroplasty versus reverse arthroplasty in the treatment of osteoarthritis with massive rotator cuff tear. In: Walch G, Boileau P, Molé D, editors. 2000 Prothèses d’épaule... recul de 2 à 10 ans. Paris. Sauramps Medical;2001 p.261-8.

5. Frankle M, Siegal S, Pupello D, Saleem A, Mighell M, Vasey M. The reverse shoulder prosthesis for glenohumeral arthritis associated with severe rotator cuff deficiency. A minimum two-year follow-up study of sixty patients. J Bone Joint Surg Am 2005;87:1697-705.

6. Guttierrez S, Comiskey CA IV, Luo ZP, Pupello DR, Franckle MA. Range of impingement-free abduction and adduction deficit after reverse shoulder arthroplasty. Hierarchy of surgical and implant design-related factors. J Bone Joint Surg Am 2008;90:2606-15. Doi:10.2106/JBJS.H00012.

7. Kelly JD, Humphrey CS,Norris TR. Optimizing glenosphere position and fixation in reverse shoulder arthroplasty. J Shoulder Elbow Surg 2008;17:589-594.

8. Kempton LB, Balasubramamiam M, Ankerson E, Wiater JM. A radiographic analysis of the effects of prosthesis design on scapular notching following reverse total shoulder arthroplasty. Journal Shoulder Elbow Surg 2011;20:571-576.

9. Lévigne C, Boileau P, Favard L, Garaud P, Molé D, Sirveaux F, Walch G. Scapular notching in reverse shoulder arthroplasty. In: Boileau P, ed. Nice Shoulder Course. Reverse Shoulder Arthroplasty. Montpellier, France: Sauramps Medical; 2006:253-272.

10. Lévigne C, Boileau P, Favard L, Garaud P, Molé D, Sirveaux F, Walch G. Scapular notching in reverse shoulder arthroplasty. J Shoulder Elbow Surg 2008;17:925-935.

11. Lévigne C, Garret J, Boileau P, Alami G, Favard L, Walch G. Scapular Notching in Reverse Shoulder Arthroplasty: Is it important to avoid it and How? Clin Orthop Relat Res 2011;469:2512-2520 DOI 10.1007/s11999-010-1695-8.

12. Lévigne C, Nérot C, Boileau P, Sirveaux F, Molé D, Favard L. Scapular notching. Rev Chir Orthop reparatrice Appa Mot 2007;93:3S74--3S81.

13. Nyffeler RW, Werner CM, Gerber C. Biomechanical relevance of glenoid component positioning in the reverse Delta III total shoulder prosthesis. J Shoulder Elbow Surg 2005;14:524-8.

14. Simovitch R, Zumstein M, Lohri E, Helmy M, Gerber C. Predictors of scapular notching in patients managed with the Delta III reverse shoulder replacement. J Bone Joint Surg Am 2007;89:588-600.

15. Sirveaux F. La prothèse de Grammont dans le traitement des arthropathies de l’épaule à coiffe détruite. A propos d’une série multicentrique de 42 cas. Faculté de médecine de Nancy, thèse de l’université de Nancy I, 1997; p.245.

16. Sirveaux F, Favard L, Oudet D, Huguet D, Walch G, Molé D. Grammont inverted total shoulder arthroplasty in the treatment of glenohumeral osteoarthritis with massive rupture of the cuff. Results of a multicentric study of 80 shoulders. J Bone joint Surg Br 2004;86:388-95.