Friday, July 1, 2016

Glenoid dysplasia - evaluation and management

As pointed out in our post earlier this month (see this link), glenoid dysplasia is a failure of normal development of the bony aspect of the glenoid side of the glenohumeral articulation. Here are some typical radiographs (Thanks for Dr Jason Hsu for this nice case example.)

Note that on the axillary view the humeral head is not decentered or subluxated relative to the glenoid articular surface (note that the term 'subluxation' is often misused in retroverted glenoids see this link).

An MRI scan shows that the posterior aspect of the glenoid socket is formed by soft tissue, rather than bone and cartilage. 

Glenoid dysplasia rarely becomes symptomatic early in life and may remain minimally symptomatic into adulthood.
Symptoms may result from stiffness, instability or arthritis.
Stiffness can usually be managed with range of motion exercises. 
Instability is less common than might be imagined. It can often be managed with strengthening the external rotators to help reduce the tendency for posterior decentering. Labral repairs, posterior glenoid osteotomy and posterior bone grafting are usually not helpful in managing posterior decentering. Work on flexibility and on external rotation range and tone, avoid bench press, pushups, focus on lat pulls and rowing as shown here:
Arthritis is initially managed with range of motion exercises, external rotator strengthening and non-steroidal anti-inflammatory medications. Surgical management is most effectively and safely accomplished with a hemiarthroplasty as shown here without attempting to change glenoid version and without attempting to resurface the glenoid. 

Note that the humeral head prosthesis is centered in the retroverted glenoid.

Dr Hsu comments on this case:

"The X-ray and the MRI are the same patient. The x-ray does not show a narrowed joint space, but that is deceiving because it actually was just a very hypertrophic inferior and posterior labrum (not cartilage) keeping the joint space open. The MRI is also deceiving because it is only one cut where there is cartilage on the humeral head.  I performed an arthroscopy first to assess the joint. If the cartilage looked okay, I planned to do a debridement and biceps procedure given the appearance of the biceps on MRI. If there was significant cartilage wear, I would convert to a hemiarthroplasty.

After putting the scope in and doing a bit of a debridement, the entire superior humeral head was devoid of cartilage, so we converted to hemiarthroplasty pretty quickly. I also debrided back a large stump of hypertrophic labrum that was forming a step-off on the glenoid face – I didn’t resect too much, just enough to make the surface smooth.

In this case, the patient was not posteriorly unstable at all – in fact, she was a bit tight in the back, so I did not need to do any additional procedures such as an eccentric head or a rotator interval plication."

Recently a Canadian colleague posed these questions about a case of  dysplasia:

"Thank you again for sharing your blog and personal experience with glenoid dysplasia. The patient I previously emailed you about (57 y.o. male - in the ppt. presentation) - he has had 2 previous arthroscopic debridements in the 1990's and more recently has tried non-op modified stretching/strengthening program + cortisone injection and continues to have severe pain (not instability) symptoms unfortunately - he has advanced arthritic changes.

He wants to move forward with surgery. I have discussed that all procedures seem unpredictable. I have consented him for a hemiarthroplasty. I know after discussing this case with you, this is your "go to operation" for this shoulder condition when patients fail non-op care. I have a couple quick questions as it pertains to the hemi procedure:

1. As with all shoulder procedures, there is a risk that the hemi procedure does not work for this patient and he continues to have persistent shoulder pain (likely from glenoid erosive changes) .... in your experience, what have you offered patients as a revision procedure if the hemi fails? This is obviously not an easy revision as there are limited options due to the glenoid deficiency and inability to implant a glenoid component. I don't want to go into the procedure thinking that it will fail, but at the same time, its nice to know of a revision option (haha)

2. Is there any role for a "stemless" HH replacement or even a "resurfacing" humeral cmpt to preserve humeral bone stock?

3. Is there any role to performing a small amount of glenoid reaming (ream and run) to stimulate a biological response (fibrocartilage)? --- this would not be performed to make any version correction but more to stimulate a biological response to decrease incidence of glenoid erosion. Based on the dysplastic nature of the glenoid, I would think reaming is not possible

4. any role for using an "inset glenoid"  --- perhaps this would be a revision option .... not sure how successful it would be for the primary procedure?

5. has a CT scan preoperatively helped you determine if a glenoid component can be implanted? or in your experience, most if not all truly dysplastic glenoids do not permit implantation of a standard glenoid? This is why I wonder about this "inlay" option (not a lot of glenoid bone stock is required) ---- new technology though which makes me concerned"

We responded: 
In specific answer to your five questions:
(1) We come to hemi for the well-informed well-motivated patient with dysplasia+substantial cartilage loss by process of exclusion: TSA and R and R are risky, RSA often complex and too much for the younger patient.
We tell them that this is our best option, but that the results are not guaranteed. We tell them there is no good revision option if this fails.
(2) We can see zero advantage of stemless or resurfacing in that loss of humeral bone stock is not an issue with a hemiarthroplasty with impaction grafting and that they take away the option of an anteriorly eccentric head which may be necessary in these cases.
(3) We would not ream – difficult and unlikely to help
(4) We love the inventor of the inset glenoid, but have not fallen in love with the prosthesis
(5) We do not get more useful information from a CT scan (more radiation more expense) than we get from a standardized axillary view (as shown above). These cases point out the fallacy of using the scapular plane to define subluxation (draw Friedman’s line to see why). Subluxation is defined as the posterior displacement of the humeral head in relation to the glenoid face. In your case, there is not a lot of posterior subluxation on your well-done axillary view! We’d not be thinking about a plastic glenoid for fear of failure

Here are some other relevant posts: