Shoulder arthroplasty for osteoarthritis in the setting of dysplastic arthritic glenoid

Although the Walch classification is widely used in the description of the glenoid version, it seems that not all arthritic glenoid deformities fit this classification system. There is no doubt that the most challenging cases of glenoid arthritic deformities are the type C glenoids as demonstrated below.

Most of time the type C glenoid represents a combination of posterior humeral de-centering, with bone deficiency of the glenoid posteriorly as well as posterior erosion and retroversion of the glenoid surface. Exposure and reaming of the glenoid can be very difficult as insertion of a reamer requires further posterior translation of the humerus.

Correction of the retroversion with resection of anterior glenoid bone is not recommended as this requires significant bone removal, reaming pass the subchondral plate and exposure of cancellous bone which does not provide good fixation for a glenoid implant. In addition, such bone resection will eventually decrease the size of the glenoid and lead to smaller glenoid -socket- which increases instability.

Below is a case of primary osteoarthritis of the shoulder with significant retroversion and a type C glenoid. The retroversion was to 60 degrees which was addressed with concentric reaming of the glenoid and implantation of an anterior eccentric head, as well as, closure of the rotator cuff interval.

The AP xray above demonstrates the medial erosion of the glenoid as shown by the acromial index. The method of calculation of the acromion index is shown below.

The axillary x-ray was not "a true" axillary view as the spinoglenoid notch cannot be seen. For this reason a CT was obtained which gives better understanding of the glenoid deformity.

There was 60 degrees of retroversion of the glenoid while the humeral head was posteriorly subluxated. As shown below the ration of AB/AC should be approximately 50% in order for the humeral head to "sit" in the center of the glenoid. In our case this ratio was 0%.

The AB/AC ratio was increased with placement of an anteriorly directed eccentric head. The humeral cut was "conservative" to avoid "under-stuffing of the joint and instability. The drop-back during passive forward elevation was addressed with soft tissue balancing by closure of the rotator cuff interval

As seen on this last x-ray, hypothetical implantation of a glenoid component would have placed the construct in high risk of early glenoid failure due to posterior edge loading of the glenoid implant. For this reason a hemi-arthroplasty was performed with concentric reaming of the glenoid. 

Six months after surgery she has significant improvement in active forward elevation with near full active forward elevation.

Simulation of her postoperative motion is shown below

Short stems in the treatment of post-traumatic humeral head avascular necrosis with retained hardware

Fixation of the humeral stem in the humeral canal is achieved at the tip of the stem and at the calcar area of the humeral head. Patients with retained proximal humerus plates and avascular necrosis of the humeral head are good candidates for short stems as long as they have good bone density proximally at the humerus for fixation of the stem. It seems that this is the ideal case scenario to avoid loosening and failure of the implant.

The following x-rays are of a patient who had two prior surgeries and had zero degrees of shoulder external rotation in full adduction. In 90 degrees of abduction the external rotation was to 0 and internal rotation to 45 degrees. Active forward elevation was to 70 degrees.

There is post-collapse avascular necrosis with dense bone proximally on the Grashey view. On the axillary view the there is posterior subluxation on a Walch type B glenoid.

Preop planning to assess how much bone needs to be removed with humeral cut

Posterior subluxation of the humerus relative to glenoid

Based on the work of Saltzman, Mercer et al.

J Shoulder Elbow Surg. 2011 Apr;20(3):363-71. A reproducible and practical method for documenting the position of the humeral head center relative to the scapula on standardized plain radiographs.

Center of rotation in normal shoulders is seen above, by the work done at UW.




The dense AVN and hard bone required the use of the flexible reamers for reaming to avoid iatrogenic fracture or penetration

The plate was retained and the center of rotation reproduced with a short stem hemi prosthesis

Anterior inferior eccentric head and anterior eccentric humeral canal reaming and implant position eliminated the subluxation

The surgery was completed with implantation of a short non cemented stem by removing proximal locking and non locking screws. The benefit of this approach is the following:

1. Less soft tissue dissection
2. Preservation of the plate, eliminates the risk of stress riser development through the screw holes of the plate
3. If cemented is required there is no distal cement extravasation
4. Overlapping of the prosthesis with the plate minimizes the risk of stress riser between the two implants
5. Eccentric humeral head directed anteriorly or anterio-inferiorly corrects the posterior subluxation of the humeral head as seen on axillary x-ray.
6. Most importantly, a future revision surgery is not complicated as removal of the undersized non cemented stem is easy with preserved proximal humeral bone.

Patient selection is important when a decision is made to use this approach in revision cases.

Short stems in reverse total shoulder arthroplasty

Short stems with metaphyseal fixation are attractive to surgeons as they provide the option of easier revision or extraction if necessary. In addition, the "curved" and not straight humeral endosteal canal is reamed asymmetrically when conventional stems are used which creates a stress riser at the tip of the long stems. Undersizing the stem distally is an option to avoid this problem. Regardless of the approach used, the modulus of elasticity of the bone is different compared to metal and the risk of peri-prosthetic fracture cannot be eliminated. Below is an example of short stem - press fit used in reverse total shoulder arthroplasty which may provide the benefit of minimizing asymmetric reaming at the tip of the stem.

Posterior chondrolabral cleft and recurrent shoulder instability

Posterior chondrolabral clefts are associated with glenoid dysplasia and 35% of the time are bilateral according to a study published by the Hospital for Special Surgery (HSS). Although it is difficult to determine whether these lesions are associated with multidirectional, posterior or anterior instability it is recommended to perform examination under anesthesia to evaluate the direction of dislocation or subluxation of the humeral head. The following case is a teenager with a 6 month history of subluxations that were associated with spasms of the anterior shoulder musculature. The patient was treated with 6 months of therapy without improvement of the instability symptoms.

Chondrolabral clefts are located in the posterior inferior labrum, according a HSS study. MRI study studies show that are not normal anatomic variants as there are associated with rounded posterior glenoid rims, glenoid dysplasia and future instability.

Schematic preservation of the rounded posterior glenoid rim

Exam under anesthesia and fluoroscopy demonstrated posterior subluxation of the humeral head on the axillary view with the load and shift test.

Anterior directed force with load and shift test shows no dislocation

Posterior subluxation during load and shift test under anesthesia

MRI demonstrates 1. Round posterior glenoid rim 2. Chondrolabral cleft at the posterior inferior glenoid

Rounded posterior rim of the glenoid and chondrolabral cleft on MRI

Exam under anesthesia demonstrated no dislocation with the load and shift test.

6 o ' clock glenoid 

Chondrolabral cleft posterior

Arthroscopic load and shift test demonstrated posterior subluxation of the humeral head  (+2 on the load and shift test).

Anterior directed force shows no subluxation during load and shift test

Posterior directed force during load and shift test shows posterior subluxation

Capsulolabral repair using three sutures

One suture anteriorly at the bankart area was placed to complete the capsulolabral repair.

Arthroscopic capsulolabral repair was performed at the area of the cleft. An additional suture for reduction of the capsular volume was placed at the Bankart area where the capsulolabral repair was re-enforced. No anchors were used in this case.

It is speculated that the glenoid dysplasia in combination with the loss of the concavity compression and negative suction pressure leads to instability. Closure of the cleft and shoulder joint capsule reduction seems to be an effective method of addressing the problem.