47.1.1 Goals

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  To restore a more neutral version of the glenoid (0–7 degrees) and establish a more centralized glenohumeral contact.

  
  
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  To mitigate the high posterior contact seen at higher retroversion.

  
  
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  To allow for a properly sized and adequately fixed glenoid component in primary total shoulder arthroplasty (TSA).

47.1.2 Advantages

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  Prevent early component loosening and failure by correcting glenoid retroversion.

  
  
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  Decrease risk of peripheral peg penetration into the glenoid vault by correcting glenoid retroversion with excessive anterior glenoid vault bone loss.

  
  
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  Biologic solution for extreme glenoid bone loss or deformity.

  
  
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  Avoids eccentric reaming, which has been shown to reduce bone density of the remaining bone at the fixation surface for glenoid component in TSA.

47.1.3 Indications

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  Classic Walch B2 consisting of “biconcave” glenoid wear pattern.

  
  
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  Walch B3 modification consisting of monoconcave glenoid with preferential posterior wear.

  
  
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  Humeral head subluxation greater than 75% (cannot be safely corrected with eccentric anterior reaming).

  
  
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  Glenoids with retroversion greater than 15 degrees (cannot be safely corrected with eccentric anterior reaming); therefore, bone graft, augmented implants, or patient-specific implants are better options depending upon the degree of deformity.

47.1.4 Contraindications

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  Uncontained surface defects as seen in primary arthroplasty for osteoarthritis (OA) or rotator cuff arthropathy (these defects require structural bone grafts).

  
  
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  Excessive deformity that precludes adequate fixation and incorporation of bone graft because of compromised biomechanical forces.

47.2.1 Preoperative Planning

Measurement of Glenoid Bone Loss for Fossa Defect in Osteoarthritis

In addition to standard anteroposterior (AP)/lateral X-ray imaging, an axillary X-ray is helpful to evaluate posterior wear. Up to 40% of patients have some extent of posterior wear. The specific amount of bone loss may be difficult to quantify on radiographs. CT imaging (2D and 3D) is extremely valuable to reliably and accurately gauge glenoid retroversion. Classification systems are based on axial imaging; thus, CT imaging is critical ( Fig. 47.1 ). Superimposing the patient’s contralateral normal scapula over the abnormal scapula is one way to help elucidate the degree of posterior fossa bone loss while also showing the abnormal shape of the glenoid secondary to osteophyte formation. MRI can be helpful in making the distinction between the paleoglenoid (native) and the neoglenoid. Thus, with T1- and T2-weighted images, there may be better identification of the “hidden” biconcave glenoid.

Patient-specific guides and operative planning tools are now available in the difficult cases to plan for graft size, shape, and implant positioning ( Fig. 47.2 ).

Related posts:

45 Posterior Glenoid Wear in Total Shoulder Replacement: Eccentric Reaming 46 Posterior Glenoid Wear in Anatomic Total Shoulder Replacement: Augmented Polyethylene Glenoid Component 48 Convertible Components in Shoulder Arthroplasty 58 Stem Removal: Humeral Osteotomy 43 Stemless Anatomic Shoulder Replacement 39 Deltopectoral Approach for Shoulder Arthroplasty

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