Conflicts of Interest Consulting (C), Royalty (R)

Transcription

1 Principles of Anatomic Total Shoulder Arthroplasty Joseph P. Iannotti MD, PhD Maynard Madden Professor and Chairman Orthopaedic and Rheumatologic Institute Cleveland Clinic Conflicts of Interest Consulting (C), Royalty (R) DePuy Johnson and Johnson (R) DJO Orthopaedics (C) Tornier (R) Zimmer (R) Integra (C,R) Custom Orthopaedic Solutions (C) Failed Arthroplasty Literature: 10% of anatomic total shoulder arthroplasty fail from loosening or glenoid wear after years Non anatomic replacement is responsible for early failures. How to avoid component malposition 1

2 How do you define an anatomic humeral head replacement? Size of the humeral head: radius of curvature and humeral head thickness Location of the humeral head: eccentric taper NSA varies degrees The Normal Humeral Head can be approximated by a sphere defined by three lateral landmarks in the sagital plane Youdarian el al JSES

3 Intra-operative assessement of humeral head size and location Intraoperative templating 2D post operative assessment 3

4 Standard OA Shoulder: What Went Wrong? Assessment of the Glenoid OA is the most common indication for TSA At least 75% of patients have some posterior bone loss resulting in increased glenoid retroversion Defining the Vault Shape The interior of the glenoid vault is a complex shape Can this shape be defined and is it consistent between individuals? 4

5 The Glenoid Vault Defined: Solid Computer Models of the Shape Codsi JSES 2007 Use of the Glenoid Vault Model to Define Glenoid Bone Loss Normal side Abnormal side Scalise et al JSES 2007 (12 samples less than 1% difference in calculated bone loss and 3 degrees of version between the two methods, kappa value 0.75) Use of the vault model to define glenoid bone loss and native glenoid version and joint line Patient Normal version varies 0 to 15 Average -6.0 Scalise JSES

6 Glenoid Vault Bone Model Define pre operative glenoid version and inclination and the location of the joint line (lateral offset) Helps in selection of the optimal implant and its location to restore pre morbid joint line Clinical Significance of Retroverted Glenoid Component Ho et al (JBJS 2012 accepted) - Clinical study of anchor peg glenoid 67 cases 2-8 year follow up. - Osteolysis of the center peg was seen in 20 cases (30%) had a - Greater than 15 degrees of component retroversion - 5 fold increase with Osteolysis around the center peg Effect of Glenoid Component Retroversion on Glenoid Lucent Lines 1 Preoperative Retroversion (deg) Retroversion < Retroversion 25 Retroversion > 25 Grade 1 n= ± /16 (25%) 6/16 (38%) 6/16 (38%) Grade 2 & 3 n= ± /37 (43%) 18/37 (49%) 3/37 (8%) Grade 1 vs. Grade 2/3 p=0.036* p=0.031* Last X-ray FU Time (years) 5.1 ± ± 1.5 p=0.0006* 3 Postoperative Glenoid Version Retroversion > 15 3 Postoperative Lazarus Lucency Grade 0 Grade 1 Grade 2 Grade 3 Grade 4 Grade ± (50%) 0 (0%) 2 (10%) 11 (55%) 4 (20%) 3 (15%) 0 (0%) ± (27%) 36 (80%) 9 (20%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) p=0.041* p=0.094 p<

7 Correction of Version: Ream High Side vs. Augmented Glenoid Standard implant in zero degrees of retroversion: center peg is eccentric to the center of the glenoid and the joint line is medialized over 1 cm Standard implant in native version of 8 degrees of retroversion: Center peg is now the center of the glenoid and the joint line is medialized less than 1 cm 7

8 5 mm augmented implant in native version of 8 degrees of retroversion: Center peg is now the center of the glenoid and the joint line is not medialized: Minimum bone removal [i1] Design Rationale Spherical anterior backside Conical posterior backside (13 degree angle) - Design effectively counteracts posterior loading 13 8

9 Size Range +7mm +5mm +3mm Design and Testing Results: Initial Fixation 9

10 Simulated Biologic Fixation A B C D 10

11 C-2 COR B-2 HSA = Humeral scapula alignment HGA = Humeral glenoid alignment Blue line = Native joint line In the B-2 Glenoid HSA and HGA are both Greater than zero and vary between patients Some glenoid start off with greater retroversion and C2 glenoid 11

12 Glenoid Planning 12

13 B2 Glenoid two year post op 13

14 2 year follow up Step Augmented Glenoid Preliminary Result Retrospective 40 patients - 29 males, 11 females years old Mean f/u 22 months Inclusion: - Osteoarthritis - Primary arthroplasty Exclusion: - Revision - RA (diagnosed or presumed) - Post-capsulorrhaphy - Post-traumatic/-instability - Poor quality radiographs Modified Walch Classification B2 premorbid glenoid >25% B3 premorbid glenoid <25% C also subclassified as C1 and C2 14

15 Osteolysis Osteolysis Grade 1 No Osteolysis Grade 2 A B B3 and C Bone Ingrowth Grade 3 More osteolysis in more pathologic glenoids (p=0.017) - A 0% - B2 13% - B3 and C 33.3% CHANGE in alignment at FINAL follow up by Walch class Recurrent subluxation - A and B2 0 patients - B3 and C -- 2 patients, both C2 1 patient revised for loosening - C2 No posterior humeral head instability (dislocation) Two subscap failures - One repaired and recentered - One unrepaired, anteriorly subluxated ROM and PENN Shoulder Score Pre op 2-3 year follow up Forward elevation 112 ± ± 19 Ext rot 21 ± ± 17 Int rot L5 ± 4 T11 ± 3 PENN Score 24.6 ± ± 17.3 Significant improvements in ROM and Penn No differences based on preop morphology or postop osteolysis grade 15

16 Conclusions Despite similar post- operative alignment, preop morphology influenced osteolysis when using a stepped glenoid B3s, C1s, C2s may be better served with different augment shapes or RSA Comparative study is required Summary A stepped augmented glenoid can be successful for management of acquired glenoid posterior bone loss: Best B2 Stepped bone graft for the younger and active patient Augmented step glenoid is best used for a B2 glenoid Unclear of best management for the B3, C1 and C2 glenoid : Consider a reverse especially older patient Thank You 16