Total Shoulder Arthroplasty: Glenoid Component - Wheeless' Textbook of Orthopaedics

- Discussion:
- indications are controversial;
- this needs to be performed prior to insertion of the humeral component;
- increased glenoid loosening rates from eccentric loading & excessive glenoid wear can be expected with w/ rotator cuff arthropathy;
- glenoid version:
- in the report by RS Churchill MD et al, 344 human scapular bones (172 matched pairs) were measured for their
glenoid height, width, inclination, and version;
- sample consisted of 50 black men, 50 white men, 50 black women, and 22 white women, all of whom were
aged 20 to 30 years at the time of death;
- no difference in glenoid size was noted between black and white patients;
- overall glenoid version for the entire study group was 1.23° of retroversion;
- difference in glenoid version between black and white patients was statistically significant;
- average glenoid version for black and white patients measured 0.20° and 2.65° of retroversion, respectively (P = .000014);
- the glenoid version for black and white men measured 0.11° and 2.87° of retroversion, respectively (P = .00034);
- glenoid version for black and white women measured 0.30° and 2.16° of retroversion, respectively (P = .034);
- no statistical difference in glenoid version was found between men and women of the same race;
- ref: Glenoid size, inclination, and version: An anatomic study.
R. Sean Churchill, MD. J Shoulder Elbow Surg 2001;10:327-32
- bone loss:
- posterior bone loss:
- many w/ osteoarthritis have posterior glenoid bone loss, where as pts w/ rheumatoid arthritis may have central (medial) erosion;
- if postior glenoid erosion is present, it may be necessary to alter amount of humeral retroversion from nl 35 deg to a less retroverted position;
- hence the glenoid will be positioned in more retroversion than normal, but the humeral head will be in less retroversion, and therefore the two
will balance each other out;
- w/ more substantial posteior erosion, then a glenoid component w/ posterior augmentation will be necessary;
- central bone loss:
- in many cases, can be managed w/ bone grafting or use of a larger portion of cement;
- references:
- Glenoid bone-grafting in total shoulder arthroplasty.
- glenoid resurfacing:
- alternative to glenoid resurfacing;
- in pts w/ OA or RA has yielded excellent clinical results;
- bone grafting:
- indicated for glenoid insufficiency w/ insufficient bone stock for appropriate component fixation:
- cortical penetration of component keel into the glenoid neck;
- incomplete peripheral contact of the glenoid component flange;
- greater than 20 deg of retroversion or anteversion of the glenoid component;
- alteration of glenoid version may affect glenoid component fixation in these patients;
- in the report by JM Hill MD et al, the authors evaluated the long-term results associated with the use of
bone-grafting for restoration of glenoid volume and version at the time of total shoulder arthroplasty;
- 21 shoulders received an internally fixed, corticocancellous bone graft for the restoration of peripheral
glenoid bone stock at the time of total shoulder arthroplasty between 1980 and 1989;
- grafting was indicated when glenoid bone stock was insufficient to maintain adequate version or fixation of the prosthesis;
- 17 shoulders were available for follow-up; the average duration of follow-up for the thirteen shoulders that did not have prosthetic
failure within the first two years was seventy months;
- TSR was performed because of osteoarthritis in five shoulders, chronic anterior fracture-dislocation
in five, capsulorrhaphy arthropathy in three, inflammatory arthritis in two, recurrent dislocation
in one, and failure of a previous arthroplasty in one;
- all patients had some form of anterior or posterior instability preoperatively;
- there were five anterior and twelve posterior glenoid defects.
- bone from the resected humeral head was used for grafting in fifteen shoulders, and bicortical
iliac-crest bone was used in two;
- average glenoid version after grafting was 4° of retroversion, with an average correction of 33°;
- range of glenoid version was 22° of anteversion to 30° of retroversion
- graft failed to maintain the original correction in three shoulders due to nonunion, dissolution, or shift;
- 5 total shoulder replacements failed, necessitating glenoid revision at two to ninety-one months postoperatively;
- failures were associated with recurrent massive cuff tears (one shoulder), persistent instability (two shoulders), improper
component placement (one shoulder), and loss of graft fixation (one shoulder);
- grafts that were used for posterior defects were technically more difficult to place and transfix than
were those used for anterior defects;
- 1/5 components that had been inserted with an anterior graft failed;
- 4/12 components that had been inserted with a posterior graft failed;
- according to the criteria of Neer et al., the functional result was rated as excellent in three shoulders,
satisfactory in six, and unsatisfactory in eight;
- ref: Long-Term Results of Total Shoulder Arthroplasty Following Bone-Grafting of the Glenoid
James M. Hill, MD JBJS (Am) 83:877-883 (2001)

- Complications:
- excessive offset (over stuffing the shoulder):
- "over-stuffing the shoulder" with placement of a glenoid component will lateralize the humeral component and
will place the subscapularis tendon under increased tension and risk rupture;
- avoid excessively large components and neck lengths since this will increase capsular tension and will result
in decrease in motion and increase instability;
- surgeon should be able to pass one finger between the acromion and the prosthetic head, should be able to inferiorly translate the humeral
head so that one half of the glenoid is exposed;
- humeral head component should allow enough posterior translation in order to allow exposure of the anterior half of the glenoid (about 15 mm of posterior translation);
- the abducted arm should allow 70 deg of internal rotation and 40 deg of external rotation;
- overstuffing the joint is more likely with total shoulder replacement (rather than hemiarthroplasty) because the glenoid component will add to the offset;
- glenoid lossening:
- radiolucencies around the glenoid component will eventually be seen in 60% of patients;
- some authors note that in many cases radiographs may fail to show loosening because the radiographic beam is not perpendicular
to the bone-component interface;
- flouroscopically positioned radiographs may improve radiographic diagnosis of loosening;

Total shoulder arthroplasty versus hemiarthroplasty for rheumatoid arthritis of the shoulder: Results of 303 consecutive cases