Monday, November 18, 2024

A B2 glenoid in a 67 year old man - 12 year followup after a basic arthroplasty

 An active man in his mid 60s presented with pain and stiffness of his left shoulder. His radiographs at presentation showed an arthritic shoulder with the humeral head posteriorly decentered on a retroverted biconcave glenoid.


After discussion of the option of a reverse total shoulder, he elected to proceed with an anatomic total shoulder.

The procedure was performed without preoperative CT scanning or preoperative 3D planning. General anesthesia was used without a nerve block. The shoulder was exposed with a subscapularis peel preserving the long head of the biceps. The glenoid was conservatively reamed without attempting to alter version. A standard non-augmented all polyethylene glenoid with an ingrowth central peg was used. The standard length smooth humeral stem was fixed with impaction autografting. 

At the age of 80, he returned for routine followup. His 12 year x-rays (shown below) reveal no evidence of stress shielding, component loosening, or instability.

 He reported excellent comfort and function. 


You can support cutting edge shoulder research that is leading to better care for patients with shoulder problems, click on this link

Follow on twitter/X: https://x.com/RickMatsen

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). 


Saturday, November 16, 2024

Using humeral head geometry to establish immediate postoperative mobility and stability in a B2 glenoid

A man in his 50s from another state presented with a grinding and aching pain in his left shoulder after prior arthroscopic surgery and cortisone injections. 

On his Simple Shoulder Test he reported the inability to tuck in his shirt behind his back, to place his hand behind his head with his elbow out to the side, to lift a gallon of milk, to toss under hand, to throw overhand, and had difficulty doing his work as a general contractor.  He was previously a competitive archer, however he was currently unable to hold his bow properly given the range of motion deficits and pain in his left shoulder.

His examination revealed 140 degrees of humerothoracic motion of which only 80 degrees was humeroscapular. External rotation was limited to 0 degrees at the side and 10 degrees with the arm in abduction. Internal rotation with the arm abducted was 10 degrees. Reach up the back was to the gluteal area. 

His preoperative x-rays are shown below. The axillary truth view showed severe posterior decentering of the humeral head on a biconcave glenoid. 

After discussion of the options of an anatomic and a reverse total shoulder, the patient elected a ream and run procedure

The surgical challenge was to manage the posterior instability while loosening this tight shoulder (avoiding overstuffing).  Without using a preoperative CT or 3D planning, it was anticipated that the posterior decentering would require the use of an anteriorly eccentric humeral head component with a short stem to provide secure fixation that would resist eccentric loading.

At surgery, the stiffness of the shoulder was confirmed on examination under general anesthesia, no nerve block was used. The shoulder was approached through a deltopectoral incision and a subscapularis peel. The long head of the biceps was preserved. 

The humeral head was deformed as anticipated.

Extensive subscapularis and anterior / inferior capsular releases were performed as shown in these diagrams from Steve Lippitt.



The glenoid was conservatively reamed to a single concavity without attempting to "correct" glenoid retroversion.

The sizing of the humeral head component was determined by trialing, paying attention to the 40, 50, 60 rules and assuring that easy flexion to at least 150 degrees could be achieved.

Implant manufacturers typically describe the size of their humeral head components in terms of diameter of curvature and height.

It is useful to recognize that the humeral head component is a spherical cap (shown in blue below) with a height of h and a radius of r (half the diameter of curvature).

The volume of the humeral head is an important factor in determining the degree of stuffing of the joint. The humeral head volume is determined by 

The effect of changing the diameter curvature and the height of the humeral component are show in diagrams below. As pointed out by Jason Hsu, increasing the height has a greater effect on humeral head volume than increasing the diameter of curvature.

This effect is quantitatively demonstrated in the table below showing the humeral head volume for a commonly used range of prosthetic humeral head diameters and radii. The different component geometries are arranged in order of decreasing head volume. Note that it is the head height that is the primary driver of joint volume.


In this case a 54 20 head provided the necessary stability and mobility as demonstrated by this photo taken after wound closure.


His immediate postoperative x-rays show the impaction grafted humeral stem with an anteriorly eccentric humeral head centered in the conservatively reamed glenoid. 

Four days after his surgery he reported that he was taking only Tylenol for his shoulder and sent this report:

 

You can support cutting edge shoulder research that is leading to better care for patients with shoulder problems, click on this link

Follow on twitter/X: https://x.com/RickMatsen

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). 



Can Computer Vision/AI solve a challenge in clinical shoulder arthroplasty research?

Shoulder surgeons are trying to understand the clinical importance of preoperative shoulder pathoanatomy and its modification by arthroplasty. Large-scale multicenter studies are necessary for investigating the relationship between standardized preoperative and sequential postoperative anatomical measurements and the outcome realized by the patient. 

The validity of such studies will depend on (1) standardization of the measurement methods across different centers, (2) human-observer independency avoiding the risk of inter-observer variation and observer bias, and (3) highly efficient methods that enable the evaluation of very large numbers of images. While CT scans are commonly used for characterizing preoperative shoulder anatomy, they are impractical for evaluating the postoperative anatomy and changes over time.  Standardized anteroposterior and axillary radiographs provide a practical and cost-effective approach for making preoperative and postoperative measurements using the same imaging method.

A recent study, Can computer vision / artificial intelligence locate key reference points and make clinically relevant measurements on axillary radiographs? demonstrated the potential of artificial intelligence in assessing clinically important relationships on standardized axillary x-rays. Standardized pre and post arthroplasty axillary radiographs were manually annotated by shoulder surgeons locating six reference points as shown the figure below:


The anterior and posterior edges of the glenoid face are indicated by the green dots.

The center of the glenoid face by the blue dot.

The base of the glenoid vault by the yellow dot. 

The spinoglenoid notch by black dot at tip of arrow.

The circle fitting the humerus articular surface by the blue circle.


These points were then used to measure glenoid version and humeroglenoid alignment (HGA-AP). Version was measured as the angle between the red and green lines. HGA-AP was measured as the perpendicular distance (double headed arrow) between the centre of the circle (star) and the perpendicular bisector (yellow line) of the glenoid face line (red line) divided by the diameter of the circle (dotted white line)




These annotated images were used to train a computer vision model that could identify these reference points and determine humeroglenoid alignment in the anterior to posterior direction and glenoid version without human guidance. 


The model's accuracy was tested on a separate test set of 52 axillary images that were not used in training the model, comparing the model's reference point locations, humero-glenoid alignment and glenoid version to the corresponding values assessed by the two surgeons. 


The model performed efficiently, allowing the rapid uploading of images and analysis of reference points, glenoid version, and humeroglenoid alignment (HGA-AP) without human participation. The model was able to produce the measurements in a matter of seconds compared to approximately two hours required for surgeon assessment of the relatively small set of 52 images.


The model was able to rapidly identify all six reference point locations to within a mean of 2 mm of the surgeon-assessed points. The mean variation in alignment and version measurements between the surgeon assessors and the model was similar to the variation between the two surgeon assessors.


The average differences between the surgeon- and the model-assessed reference points for the test set are shown below



The mean differences in glenoid version and HGA-AP between the surgeon assessors, between each surgeon assessor and the model, and between the average of the two surgeon assessors the model is shown below



The inter-observer variability between the two surgeons was similar to that between the average of the two surgeons and model 


While it will require substantial further refinement before it is ready for broad scale application, this proof-of-principle study does demonstrate the development and validation of a computer vision/artificial intelligence model that can independently identify key landmarks and determine the glenohumeral relationship and glenoid version on axillary radiographs. This observer-independent approach has the potential to enable efficient assessment of shoulder radiographs, substantially lessening the burden of manual x-ray interpretation and enabling scaling of these measurements across large numbers of patients from multiple centers so that pre- and postoperative anatomy can be correlated with patient reported clinical outcomes. 


Other studies have reported the use of artificial intelligence to classify shoulder implants 


Classifying shoulder implants in X-ray images using deep learning "In a data set containing X-ray images of shoulder implants from 4 manufacturers and 16 different models, deep learning is able to identify the correct manufacturer with an accuracy of approximately 80% in 10-fold cross validation, while other classifiers achieve an accuracy of 56% or less"


Development of a machine learning algorithm to identify total and reverse shoulder arthroplasty implants from X-ray images. "This proof of concept study demonstrates that machine learning can assist with preoperative planning and improve cost-efficiency in shoulder surgery."


A novel hybrid machine learning based system to classify shoulder implant manufacturers. "The proposed hybrid machine learning algorithms achieve the goal of low cost and high performance compared to other studies in the literature."


Deep learning to automatically classify very large sets of preoperative and postoperative shoulder arthroplasty radiographs. "We developed an efficient, accurate, and reliable AI algorithm to automatically identify key imaging features of laterality, imaging view, and implant type in shoulder radiographs. This algorithm represents the first step to automatically classify and organize shoulder radiographs on a large scale in very little time, which will profoundly enrich shoulder arthroplasty registries."


Artificial intelligence for automated identification of total shoulder arthroplasty implants. "A DL model demonstrated excellent accuracy in identifying 22 unique TSA implants from 8 manufacturers. "


EFFICACY OF ARTIFICIAL INTELLIGENCE-BASED MODELS FOR SHOULDER ARTHROPLASTY IMPLANT DETECTION AND CLASSIFICATION USING UPPER LIMB RADIOGRAPHS: A SYSTEMATIC REVIEW AND META-ANALYSIS "AI-based classification of shoulder implant types can be considered a sensitive method."


Other studies have explored the use of artificial intelligence to make measurements on x-ray images


The Development of a Yolov8-Based Model for the Measurement of Critical Shoulder Angle (CSA), Lateral Acromion Angle (LAA), and Acromion Index (AI) from Shoulder X-ray Images. "The results indicated that automatic measurement methods align with manual measurements with high accuracy and offer an effective alternative for clinical applications".


The acetabularization index: a novel measure of acromial bone loss prior to reverse shoulder arthroplasty. "AI is a reliably measurable tool on radiographs and 2D CT scans"


While others have used artificial intelligence to assess humeral fractures


Clinical validation of artificial intelligence-based preoperative virtual reduction for Neer 3- or 4-part proximal humerus fractures "The AI-based preoperative virtual reduction model showed good performance in the reduction model in proximal humerus fractures with faster working times."


Artificial intelligence versus radiologist in the accuracy of fracture detection based on computed tomography images: a multi-dimensional, multi-region analysis "The optimized AI model improves the diagnostic efficacy in detecting extremity fractures on radiographs, and the optimized AI model is significantly better than radiologists in detecting avulsion fractures, "


From the foregoing it is evident that we are on the forefront of the application of computer vision/artificial intelligence to enhance clinically important shoulder research. 


Stay tuned!



You can support cutting edge shoulder research that is leading to better care for patients with shoulder problems, click on this link

Follow on twitter/X: https://x.com/RickMatsen

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). 


Thursday, November 14, 2024

Periprosthetic infections of the shoulder - Part 2

Treatment

There is no "standard" treatment for shoulder periprosthetic infections because of the wide variety in clinical presentation (obvious vs stealth), the condition of the patient (septic, frail or otherwise healthy), and the condition of the bone (fragile or strong, cemented, well fixed, or loose implants). 

Thus, the surgeon must customize the treatment to each clinical situation.

Our philosophy is to prioritize preservation of shoulder function over clearance of all bacteria from the surgical field (recognizing that no approach to the treatment of periprosthetic infections can reliably sterilize the surgical field).

Below is a summary of the recent literature and some of our thoughts to aid the surgeon in clinical decision making.

It is essential that every attempt be made to obtain cultures before starting a course of antibiotic therapy, otherwise the chances of identifying the pathogen may be lost. However, in approaching a revision surgery for suspected periprosthetic infection, it is probably ok to administer immediate preoperative antibiotics in that their administration does not seem to alter the results of deep intraoperative cultures.

Debridement, antibiotics, with implant retention DAIR seems particularly applicable in acute obvious infections in shoulders with securely fixed and stable implants (link, link, link, link). Surgeons can consider a partial implant exchange to enable better access for debridement, such as the removal and replacement of a humeral liner in a reverse total shoulder. However, this approach appears to be less effective in resolving the infection than implant exchange, probably because of bacteria-containing biofilms adherent to the implants in established infections (link, link). Some advocate repeating this procedure, the double DAIR.

Complete single stage appears to be the preferred treatment when a periprosthetic infection is suspected, provided that that the existing implants can be removed without excessive damage to the bone of the humerus and glenoid. The single stage is covered in detail in this post. The effectiveness of the single stage - as well as its safety in comparison to the two stage approach - are covered in quite a number of publications (link, linklink, link, link, link, link, link, link, link, link, link, link, link, link, link, link, link, link, link).

Some surgeons advocate the use of a reamer-irrigator-aspirator (RIA) system for cleaning out the medullary canal of long bones, such as the humerus.

The essentials of our approach to the single stage are shown below.


A variation on the single stage, is the Paused Singe Stage (PaSS). As pointed out by Armand Hatzidakis and Jason Hsu  this approach can be useful in the management of a patient who is systemically ill from an obvious infection. It prioritizes debridement while avoiding damaging the remaining bone to an extent that would compromise later reconstruction - this can be referred to as "unresectable hardware". After the debridement, a wound vac is placed with irrigation.


In this case the cultures were overwhelming positive for MSSA

After a few days a functional implant is inserted 


While series of cases treated with PaSS are as yet unavailable, we consider this approach when a conventional single stage cannot be safely performed,

Another variation of the single stage is the functional composite spacer described by Jon LevyThis approach avoids some of the problems associated with the polymethacrylate spacer used in the usual two stage revision (glenoid wear, loosening, difficult in extraction, fracture). After debridement, the surgeon fashions a humeral hemiarthroplasty implant with antibiotic cement coated around the stem.



While large series are at present unavailable, this is a useful approach for reserving a metallic humeral head-glenoid articulation. In the initial reports some patients had good function up to five years after surgery without a second procedure.

Two Stage 
The two stage revision consists of debridement, implant removal and insertion of an antibiotic containing polymethylmethacrylate spacer followed weeks later by removal of the spacer and insertion of the definitive implant. 

A number of articles have been published regarding the two stage treatment of periprosthetic infections. Many emphasize the problems encountered with this approach (link, link, link, link, link. The two stage seems to have an increased risk in patients with high comorbidity index. It has been noted that the microbial spectrum is changed but not eliminated at the second stage (link, link, link). The two stage is more costly than other approaches. Complications are not infrequently encountered with the two stage revision (link, link, link, link, link, link, link, link). The amount of antibiotic eluted from the spacer is limited.






Spacer for life
Because of the complications associated with the second stage of the two stage approach, some surgeons have reported stopping after the first stage, leaving the spacer in for life (link, link, link, link, link, link)

Resection arthroplasty
Resection of the implants without reimplantation has been reported, but the functional outcomes are poor.

Antibiotic therapy
Surgical treatment of periprosthetic infections is accompanied by antibiotic therapy, usually determined by consultation with experts in infectious disease. 

If preoperative aspiration or biopsy reveals the causative organism, pathogen-specific therapy can be started at the time of surgical revision. If not, the antibiotic choice is made empirically. 

There is evidence supporting the use of topical vancomycin, which may reduce the need for prolonged courses of systemic antibiotics. The SOLARIO trial: SHORT OR LONG ANTIBIOTIC REGIMES IN ORTHOPAEDICS: A RANDOMISED OPEN LABEL MULTI-CENTRE CLINICAL TRIAL found that when local antibiotics are administered, a short regime (≤7 days) of systemic antibiotics was non-inferior to 4 weeks of systemic antibiotics when treating orthopaedic infections. In addition, there were substantially fewer side effects with a short regime (≤7 days) of systemic antibiotics. This approach may also help to prevent the emergence of antibiotic resistance through the overuse of antibiotics as well as saving heath care dollars. 

We commonly use preoperative intravenous ceftriaxone and vancomycin in that they offer coverage for Cutibacterium and coagulase negative staphylococcus (link, link). 

While the use of postoperative intravenous antibiotics administered via a peripherally inserted central catheter (PICC) has been commonly used, the complications and inconvenience have diminished enthusiasm for this approach (link, link). An important clinical trial, Oral versus Intravenous Antibiotics for Bone and Joint Infection, concluded that oral antibiotic therapy was noninferior to intravenous antibiotic therapy when used during the first 6 weeks for complex orthopedic infection, as assessed by treatment failure at 1 year. 

Recognizing that Cutibacterium is the most common organism to cause periprosthetic shoulder infections, oral doxycline seems to offer a balance between safety and efficacy in the initial postoperative treatment until the results of intraoperative cultures become available to guide subsequent therapy. 

The future - phage therapy?
Because of issues with antibiotic resistance, allergies and side effects, there is interest in the application of viral phage therapy in the treatment of periprosthetic infections. 

How effective is treatment?
It is difficult to know whether surgical and medical treatment has successfully eradicated bacteria from an infected shoulder (unless a subsequent surgery is performed with five negative deep cultures). 

There is evidence that the prognosis is worse for individuals with high levels of Cutibacterium on unprepared skin and for shoulders infected with staph aureus

The bottom line
Since the goal of treatment is preserving the comfort and function of the shoulder, perhaps the most practical approach for determining the success of treatment is through the sequential, longitudinal documentation of the patient's self-assessed comfort and the ability to perform individual important shoulder functions. 


Please join us for the AAOS Infection course!!!



Follow on twitter/X: https://x.com/RickMatsen
Follow on facebook: https://www.facebook.com/shoulder.arthritis
Follow on LinkedIn: https://www.linkedin.com/in/rick-matsen-88b1a8133/

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).