The selected article for discussion during the month of November is:

“Accuracy of Sonographically Guided and Palpation Guided Scaphotrapezio-trapezoid Joint Injections” (Smith, et al)

Access the article here

Questions for discussion:

1. The authors propose that further study is required to determine the accuracy of sonographic visualization of overflow to adjacent regions, and to explore clinical implications of that overflow.  How would you design such a study? What clinical implications would you anticipate?

2. The primary author favors the simplicity of the palmar approach for sonographically guided scaphotrapeziotrapezoid joint injections. Do you have experience with the palmar and/or dorsal approach? Based on your experience, how would you compare the ease and accuracy of the two approaches?

3. The authors suggest that future clinical investigations may focus on and determine whether sonographically guided scaphotrapeziotrapezoid joint injections confer superior clinical benefits compared to palpation guided injections in patients with symptomatic scaphotrapeziotrapezoid arthritis. How would you design such an investigation?

4. Do you have questions or comments for these authors?

The Practice Gap

Scaphotrapeziotrapezoid arthritis is a common cause of radial wrist pain in elderly populations, resulting in substantial pain and disability. Identifying symptomatic scaphotrapeziotrapezoid arthritis in the setting of carpometacarpal arthritis is crucial so that appropriate non-operative treatment, including injections, may be appropriately prescribed.  In addition, when surgery is indicated,  isolated carpometacarpal fusion or arthroplasty that does not involve excision of the trapezium is contraindicated in the setting of severe scaphotrapeziotrapezoid arthritis.  

But the diagnosis of symptomatic scaphotrapeziotrapezoid arthritis remains clinically challenging because of the complex nature and deep location of this articulation as well as the high prevalence of concomitant pain generators.

• The accuracy with which physical examination can identify symptomatic scaphotrapeziotrapezoid arthritis has not been established.
• Although radiographs may reveal scaphotrapeziotrapezoid arthritis, this finding lacks specificity for symptoms arising from this region.
• Conversely, arthroscopic studies have reported that radiographs may also lack sensitivity to detect clinically important scaphotrapeziotrapezoid arthritis in some cases.

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Research study design

• The senior author (J.S.) completed sonographically guided scaphotrapeziotrapezoid joint injections in 20 unembalmed cadaveric specimens using diluted blue latex.
• A coinvestigator (J.S.B) then completed palpation guided injections in the same 20 specimens using a diluted yellow latex solution.

All injections were completed in the Mayo Clinic Procedural Skills Laboratory, and cadaveric specimens were obtained through the Department of Anatomy’s Mayo Foundation Bequest Program.

Inclusion/Exclusion criteria: All specimens were visibly free of trauma or postsurgical changes affecting the scaphotrapezoid region of either the palmar or the dorsal hand. Fresh-frozen specimens were thawed at room temperature immediately before the study.

Injection Procedures:

• Sonographically guided injections were completed using a palmar approach.
• Palpation guided injections were performed using a dorsal approach.

Assessment:

At a minimum of 24 hours after injection, a fellowship-trained hand surgeon dissected each specimen to assess the accuracy of injectate placement. Injections were graded as accurate (latex in the scaphotrapeziotrapezoid joint) or inaccurate (no latex in the joint),

Statistics:

Descriptive statistics were used to report the accuracy of sonographically and palpation guided injections. Differences in the rates of accurate versus inaccurate injections between the two groups were assessed for significance using a 2-tailed Fisher exact test, with significance set at P < .05.

Results

• All 20 sonographically guided injections placed latex within the scaphotrapeziotrapezoid joint.
• 16/20 palpation guided injections resulted in latex being found within the same joints (80% accuracy)

Conclusions

The results of this study suggest that sonographically guided scaphotrapzeiotrapezoid joint injections performed via a palmar approach are significantly more accurate than palpation guided injections performed via a dorsal approach. Clinicians should consider using sonographic guidance to perform scaphotrapeziotrapezoid joint injections when precise intra-articular placement is paramount.