The stiff arthritic shoulder with flattened posteriorly decentered humeral head. Tips for a successful anatomic arthroplasty.

Posterior subluxation of the humeral head in primary osteoarthritis of the shoulder is common. It is usually associated with a B2 Walch glenoid deformity. When there is associated flattening of the humeral head, as seen in this case below, usually there is significant limitation is motion and stiffness. 

When planning the total shoulder anatomic replacement, it is important not to proceed with an aggressive humeral head cut. Significant decrease of the volume of the head due to an aggressive humeral head cut will help with glenoid exposure BUT it will make the posterior instability worse. While some surgeons use posterior augmented glenoid components, I prefer to address the instability with soft tissue balancing, conservative humeral head cut, eccentric humeral head - dialing eccentricity anteriorly - and possible closure of the rotator cuff interval at the end of the surgery. 

Below you will find xrays of a case that illustrates a clinical situation where such approach had to be used.

The ideal position of the glenosphere in primary reverse total shoulder arthroplasty

The reverse shoulder arthroplasty is a highly technical operation. It requires appropriate soft tissue balancing and correct component positioning. When done for primary rotator cuff arthropathy has a very high success rate in restoring mobility and providing pain relief. When Paul Grammont introduced with procedure in France in the 1980s, the rest of the world saw it with scepticism and some orthopaedic surgeons had concerns. Today, it provides solutions for problems that we did not have a solution before. Below are the radiographs of a patient that has primary rotator cuff arthropathy, the patient is an elderly individual 70 years or older.

Postoperative radiographs show a press fit stem, inferior placement of the glenosphere and overhanging inferiorly by 2mm to avoid notching. Inferior tilting of the glenoid component is seen as well.

The superior screw at the 12 o'clock position is aiming towards the base of the coracoid, the inferior 6 o'clock screw is aiming to the spine of the scapula. The posterior screw is aimed inferiorly and anteriorly and the anterior screw superiorly and posteriorly. These are important details that achieve appropriate implantation and seating of the glenosphere which is the most critical aspect of this surgery.

The overhanging of the glenosphere by 2 mm avoids impingement of the polyethylene to the scapula

Correct position of the glenosphere

The axillary view shows  the appropriate orientation of the glenosphere.

Eccentric prosthetic humeral head for Walch B2 arthritic glenoids.

The following case illustrates the benefit of using anteriorly directed eccentric head in anatomic arthroplasty to address the posterior subluxation of the humeral head seen often with a B2 arthritic glenoid. The details of the technique can be found by clicking here.

The deforming forces in proximal humerus fractures

Proximal humerus fracture fixation is challenging when there is insufficient bone density, more than 2 parts, an associated dislocation, and more importantly bone loss or impaction of the head in the setting of an obese patient or large deltoid which makes the exposure difficult. 

The deforming forces can be eliminated to a certain extend when the patient is placed in the supine position with the arm on a hand table and abducted to 90 degrees which relaxes the deltoid to allow for space retraction and application of the plate. The most significant deforming forces are:

1. Pectoralis major pulls the shaft anterior and medial

2. The greater tuberosity is pulled superiorly and posteriorly by the supraspinatus, infraspinatus and teres minor

Those forces can be significant and suture passing around the fragments can help with manipulation of the bone fragments. In the majority of cases the difficulty is in raising the articular surface, filling the defects of the bone without overstuffing and repairing the tuberosities. The head shaft angle is better tolerated in the valgus than in the varus position.

It is important to achieve the following after ORIF if possible:

a. Avoid long head screws as the most common complication is head screw penetration

b. Choose isolated screw fixation only in the young patient with good bone stock

c. Restore medial disrupted bone hinge

d. avoid step off in head splits

e. try to proceed with ORIF of head splits in young patients and avoid arthroplasty.

f. avoid superior migration of the greater tuberosity - or posterior superior migration - of more than 5 mm.

g. Pass sutures around the rotator cuff and tight them to the plate.

h. Avoid superior placement of the plate as it may impinge to the acromion with elevation of the shoulder or arm

Below is a fracture treated with ORIF taking into consideration those principles.

Proximal humerus fracture dislocation - Do we need to address the instability acutely?

This is a middle aged patient with a proximal humerus fracture dislocation. On the axillary view it is demonstrated that the humeral head is locked in a anteriorly dislocated position. The anterior inferior rim of the glenoid created the Hill Sachs lesion. The impaction was significant as the greater tuberosity is separated from the head and displaced and half of the glenoid is impacted in the humerus. Those injuries do have sometimes an associated soft tissue or bony Bankart lesion. Most of the time it is not necessary to address the instability at the time of fixation of the fracture, there is no need for repair of the soft tissues and no need for ORIF of the small glenoid fracture when it is present.

The stiffness that develops due to the proximal humerus fracture limits the ROM of the shoulder and for that reason the shoulder remains stable. Close follow up after surgery is recommended as such fractures can become unstable in the acute postoperative period.