Tips

Total Shoulder Arthroplasty Using a Bone-Sparing, Precision Multiplanar Humeral Prosthesis

Publish date: February 1, 2018

References

1. Williams GR Jr, Wong KL, Pepe MD, et al. The effect of articular malposition after total shoulder arthroplasty on glenohumeral translations, range of motion, and subacromial impingement. J Shoulder Elbow Surg. 2001;10(5):399-409.

2. Nyffeler RW, Sheikh R, Jacob HA, Gerber C. Influence of humeral prosthesis height on biomechanics of glenohumeral abduction. An in vitro study. J Bone Joint Surg Am. 2004;86-A(3):575-580.

3. Iannotti JP, Spencer EE, Winter U, Deffenbaugh D, Williams G. Prosthetic positioning in total shoulder arthroplasty. J Shoulder Elbow Surg. 2005;14(1 Supple S):111S-121S.

4. Terrier A, Ramondetti S, Merlini F, Pioletti DD, Farron A. Biomechanical consequences of humeral component malpositioning after anatomical total shoulder arthroplasty. J Shoulder Elbow Surg. 2010;19(8):1184-1190.

5. Denard PJ, Raiss P, Sowa B, Walch G. Mid- to long-term follow-up of total shoulder arthroplasty using a keeled glenoid in young adults with primary glenohumeral arthritis. J Shoulder Elbow Surg. 2013;22(7):894-900.

6. Figgie HE 3rd, Inglis AE, Goldberg VM, Ranawat CS, Figgie MP, Wile JM. An analysis of factors affecting the long-term results of total shoulder arthroplasty in inflammatory arthritis. J Arthroplasty. 1988;3(2):123-130.

7. Franta AK, Lenters TR, Mounce D, Neradilek B, Matsen FA 3rd. The complex characteristics of 282 unsatisfactory shoulder arthroplasties. J Shoulder Elbow Surg. 2007;16(5):555-562.

8. Flurin PH, Roche CP, Wright TW, Zuckerman JD. Correlation between clinical outcomes and anatomic reconstruction with anatomic total shoulder arthroplasty. Bull Hosp Jt Dis (2013). 2015;73 Suppl 1:S92-S98.

9. Kurtz S, Ong K, Lau E, Mowat F, Halpern M. Projections of primary and revision hip and knee arthroplasty in the United States from 2005 to 2030. J Bone Joint Surg Am. 2007;89(4):780-785.

10. Goldberg SS, Akyuz E, Murthi AM, Blaine T. Accuracy of humeral articular surface restoration in a novel anatomic shoulder arthroplasty technique and design: a cadaveric study. Journal of Shoulder and Elbow Arthroplasty. 2018;2:2471549217750791.

11. Iannotti JP, Gabriel JP, Schneck SL, Evans BG, Misra S. The normal glenohumeral relationships. An anatomical study of one hundred and forty shoulders. J Bone Joint Surg Am. 1992;74(4):491-500.

12. Jun BJ, Lee TQ, McGarry MH, Quigley RJ, Shin SJ, Iannotti JP. The effects of prosthetic humeral head shape on glenohumeral joint kinematics during humeral axial rotation in total shoulder arthroplasty. J Shoulder Elbow Surg. 2016;25(7):1084-1093.

13. Alidousti H, Giles JW, Emery RJH, Jeffers J. Spatial mapping of humeral head bone density. J Shoulder Elbow Surg. 2017;26(9):1653-1661.

14. Harrold F, Wigderowitz C. Humeral head arthroplasty and its ability to restore original humeral head geometry. J Shoulder Elbow Surg. 2013;22(1):115-121.

15. Hertel R, Knothe U, Ballmer FT. Geometry of the proximal humerus and implications for prosthetic design. J Shoulder Elbow Surg. 2002;11(4):331-338.

16. Wirth MA, Ondrla J, Southworth C, Kaar K, Anderson BC, Rockwood CA 3rd. Replicating proximal humeral articular geometry with a third-generation implant: a radiographic study in cadaveric shoulders. J Shoulder Elbow Surg. 2007;16(3 Suppl):S111-S116.

17. Pearl ML, Kurutz S, Postacchini R. Geometric variables in anatomic replacement of the proximal humerus: How much prosthetic geometry is necessary? J Shoulder Elbow Surg. 2009;18(3):366-370.

18. Pearl ML, Volk AG. Coronal plane geometry of the proximal humerus relevant to prosthetic arthroplasty. J Shoulder Elbow Surg. 1996;5(4):320-326.

19. Alolabi B, Youderian AR, Napolitano L, et al. Radiographic assessment of prosthetic humeral head size after anatomic shoulder arthroplasty. J Shoulder Elbow Surg. 2014;23(11):1740-1746.

The success of total shoulder arthroplasty (TSA) is largely dependent on how accurate the proximal humeral anatomy is reconstructed and the glenohumeral relationships are restored.^1-4 Numerous studies have demonstrated a relationship of worse clinical outcomes and implant failure with nonanatomic implant placement.^5-8 The majority of arthroplasty systems rely on surgeon-dependent decision-making to determine the location of the border of the articular surface and, ultimately, the amount and location of bone to be resected. Even in experienced hands, the ability to reproducibly restore the joint line is inconsistent.³

In contrast, the majority of total knee arthroplasty (TKA) systems have been designed with instrumentation that guides the surgeon precisely regarding where and how much femoral bone must be resected, and the corresponding implant is designed with the same thickness to preserve the location of the joint line. Cutting block instrumentation rather than freehand cuts enables reproducibility of TKA while being performed for an estimated 700,000 times annually in the US.⁹

To achieve similar high levels of reproducibility in shoulder arthroplasty, a new technique was developed based on the principle of providing instrumentation to assist the surgeon in accurately restoring the proximal humeral joint line. This technical article describes the technique of using a multiplanar instrumented cutting system and matching implants to perform TSA. The technique shown was previously studied and was found to allow surgeons to recreate the original anatomy of the humerus with very high precision.¹⁰

The humeral prosthesis described in this article has an articular surface that is slightly elliptical to more closely match the actual shape of the humerus bone.¹¹ Biomechanical studies have demonstrated that implants designed with a nonspherical shape have more similar motion and kinematics to those of the native humeral head.¹² The undersurface of the implant has a concave four-plane geometry that matches with the bone cuts created by the cutting guides (Figures 1, 2).

This provides rotation stability, and the implant rests on the strong subchondral bone of the proximal humerus proximal to the anatomic neck rather than relying on metaphyseal bone or canal fixation, as recommended by Aldoiusti.¹³ It also allows optimal implant placement with complete freedom with respect to inclination, version, and medial/posterior offset from the humeral canal.

Continue to: The implant respects the relationship...