In performing total shoulder arthroplasty, some surgeons advocate "correction" of preoperative retroversion by eccentrically reaming the anterior glenoid bone.
Eccentric reaming can compromise the amount of bone remaining for glenoid component fixation (see Glenoid morphology after reaming in computer-simulated total shoulder arthroplasty; Eccentric reaming in total shoulder arthroplasty: a cadaveric study; Perforation tolerance of glenoid implants to abnormal glenoid retroversion, anteversion, and medialization; Version Correction via Eccentric Reaming Compromises Remaining Bone Quality in B2 Glenoids: A Computational Study).
The two Steve Lippitt diagrams below contrast the amount of bone remaining for glenoid component support with corrective reaming (above) and with non-corrective reaming (below).
So we wondered how much was glenoid version actually changed by "corrective reaming"?
In a few studies, the preoperative to postoperative change in version was measured using the same imaging technique.
Effect of glenoid deformity on glenoid component placement in primary shoulder arthroplasty. compared retroversion measured with CT scans before and after total shoulder arthroplasty in which the surgeon attempted to correct version to zero degrees. The preoperative and postoperative retroversion is shown for their 13 patients in the chart below.
Change ranged from 3 to 11 degrees for the patients starting with >10 degrees of retroversion. The relationship between postoperative version and clinical outcome was not reported.
Serial 3D CT analysis of humeral head alignment in relation to glenoid correction and outcomes after total shoulder arthroplasty used preoperative and postoperative CT scans to assess retroversion before and after total shoulder arthroplasty in which glenoid retroversion was corrected toward neutral using asymmetric high side reaming in cases of asymmetric glenoid wear. For their 23 patients the mean preoperative version of −10 ± 7° (range, −28° to 6°) was corrected to a postoperative version of −4° ± 9° (range, −20° to 15°) (P < .001).
Average change of 6 degrees. Postoperative version did not correlate with clinical outcome.
3-dimensionally printed patient-specific glenoid drill guides vs. standard nonspecific instrumentation: a randomized controlled trial comparing the accuracy of glenoid component placement in anatomic total shoulder arthroplasty achieved an average of 12.2 degrees version correction using a patient specific guide in 19 patients with preoperative retroversion of 12.9 degrees and an average of 10.6 degree correction using a standard guide in 17 patients with a preoperative retroversion of 14.7 degrees. The average error in version correction was 3.1 degrees for the patient specific guide group and 5 degrees for the standard guide. The effect of glenoid version on clinical outcome was not reported.
However, for a large percentage of articles on corrective reaming, the resulting change in glenoid version was not measured.
Total shoulder arthroplasty in patients with a B2 glenoid addressed with corrective reaming The mean preoperative retroversion for 59 patients measured with CT scans was 18° (range, –1° to 36°). Glenoid deformities were addressed using a high side, corrective ream with the goal of achieving a final retroversion angle within 10° to 15° of neutral. The postoperative version was not measured.
Thus, the preoperative to postoperative change in version is not known.
The authors of Total Shoulder Arthroplasty for Primary Glenohumeral Osteoarthritis: does the posterior humeral subluxation persist after correction of the glenoid version at 5 years minimum? studied 62 TSA patients with 32 B2, 13 B3 and 17 type C glenoids. For the entire group preoperative retroversion by CT scan was 23° (95% CI [21-24])]. Surgery was planned preoperatively in order to obtain a 0° retroversion relative to the scapular plane using anterior asymmetric reaming. They could not analyze the change in retroversion because they did not perform an early postoperative CT scan.
Thus, the preoperative to postoperative change in version is not known.
The authors of Total shoulder arthroplasty in patients with a B2 glenoid addressed with corrective reaming: mean 8-year follow-up analyzed the radiographs for 26 shoulders having corrective reaming and total shoulder arthroplasty with standard glenoid components for shoulders with B2 arthritic pathoanatomy. A preoperative CT scan was used to define the deformity. The authors planned for an estimated glenoid retroversion correction to 10-15° of neutral. The retroversion deformity was address by high-side reaming. The average preoperative retroversion was 18.9° ± 6.7. Postoperative retroversion was not measured.
Thus, the preoperative to postoperative change in version is not known.
Outcomes of anatomic total shoulder arthroplasty in patients with excessive glenoid retroversion: a case-control study compared 40 patients treated with TSA with more than 20° of glenoid retroversion preoperatively as assessed by CT scans to a matched cohort of 80 patients with less than 20° of retroversion. In cases of eccentric wear, the glenoid typically preferentially reaming the anterior glenoid and partially correcting glenoid version. The outcomes for the two groups were similar. Postoperative CT scans were not available to assess postoperative glenoid version.
Thus, the preoperative to postoperative change in version is not known.
Comment: The amount of change resulting from "corrective" reaming was small in those few reports in which it was measured. In most reports, the authors don't present how much version was changed by corrective reaming.
Two studies suggest that it may not be clinically important to address glenoid retroversion
Does Postoperative Glenoid Retroversion Affect the 2-Year Clinical and Radiographic Outcomes for Total Shoulder Arthroplasty? presented a series of 71 patients having shoulder arthroplasty with standard glenoid components without specific attempt to modify glenoid retroversion by overreaming the anterior glenoid, bone grafting, or use of special glenoid components. These patients had standardized preoperative and postoperative radiographs. The average preoperative retroversion was 13.6 ± 11.9 degrees; the average postoperative retroversion was 10.2 ± 9.5 degrees. A 3.4 degree change. In this investigation, >15 degrees of postoperative glenoid retroversion was not associated with inferior clinical results at 2 years after surgery. The authors suggested that arthritic glenohumeral joints can be managed without specific attempts to modify glenoid version.
Glenoid retroversion does not impact clinical outcomes or implant survivorship after total shoulder arthroplasty with minimal, noncorrective reaming reviewed 151 anatomic total shoulder arthroplasties with a mean follow-up of 4.6 years. A non-augmented all polyethylene pegged glenoid component after minimal non-corrective reaming - just sufficient to provide concentricity of the reamer and the native glenoid and thus a stable fit of the glenoid implant on the bone.
The mean preoperative retroversion assessed by CT scan was 15.6° (range, 0.2-42.1). Linear regression analysis found no significant association between preoperative retroversion and any postoperative patient reported outcome. A total of 5 (3.3%) failures occurred due to glenoid implant loosening (3 patients) and Cutibacterium acnes infection (2 patients) with no association between failure causation and increased retroversion. No correlation could be found between the Walch classification and postoperative postoperative patient reported outcome. The authors conclude that anatomic total shoulder replacement with minimal and noncorrective glenoid reaming demonstrates reliable increases in patient satisfaction and clinical outcomes at a mean of 4.6-year follow-up in patients with up to 40° of native retroversion. Higher values of retroversion were not associated with early deterioration of clinical outcomes, revisions, or failures.
Here is a recent analysis of the published literature.
See also
Arthritic glenoid retroversion: what to do about it, is an augmented glenoid of value?
and
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Here are some videos that are of shoulder interest
Shoulder arthritis - what you need to know (see this link).
How to x-ray the shoulder (see this link).
The ream and run procedure (see this link).
The total shoulder arthroplasty (see this link).
The cuff tear arthropathy arthroplasty (see this link).
The reverse total shoulder arthroplasty (see this link).
The smooth and move procedure for irreparable rotator cuff tears (see this link).
Shoulder rehabilitation exercises (see this link).
