CMC Joint Injection

CMC Joint Injection (Carpometacarpal Joint) is used in case of Acute or chronic capsulitis, or OA of the CMC joint.

Equipment Needed

• Syringe: 1 ml
• Needle: Orange, 25 gauge / 0.5 inch (16 mm)
• Kenalog 40: Thumb, 10 mg / Fingers, 10 mg
• Lidocaine: 0.75 ml, 2% / 0.5 ml, 2%
• Total volume: 1 ml / 0.75 ml

Related Anatomy

The first metacarpal articulates with the trapezium. The easiest entry site is at the apex of the snuffbox on the dorsum of the wrist.

The joint line is found by passively flexing and extending the thumb while palpating for the joint space between the two bones. Mark the entry point slightly more proximally to allow for the rounded shape of the base of the metacarpal.

Be aware that the radial artery lies at the base of the snuffbox. The distal thumb joint and all finger joints can best be infiltrated from the medial or lateral aspect at the joint line, with the digit in slight flexion.

See Also: Wrist Anatomy

CMC Joint Injection Technique

• Patient rests hand in midposition, with thumb up, and applies traction of thumb with their other hand traction
• Identify gap of joint space at apex of snuffbox on dorsum of wrist
• Insert needle perpendicularly into gap
• Inject solution as a bolus

Tape the thumb using a spica technique, or tape two fingers together to splint them for a few days. The patient then begins gentle active and passive mobilizing exercise within the pain-free range and is advised against overuse of the thumb or fingers. Dipping the fingers into warm wax baths and using the wax ball as an exercise tool can be beneficial.

Notes

Ultrasound may be used to accurately perform intra-articular CMC Joint injections. Ultrasound provides a viable alternative to fluoroscopy when accurate injection into the CMC joint is required for diagnostic or therapeutic purposes.

Trapeziometacarpal joint capsulitis is a common lesion of older women, and the results of infiltration are uniformly excellent. Often, it is several years before a repeat injection is required, provided the patient does not grossly overuse the joint.

Infiltrating the thumb and finger joints can be difficult because osteophytosis will almost certainly be present. It is sometimes necessary to anaesthetize the capsule with some of the solution while trying to enter the joint. Gapping the side of the joint being entered also helps, and an even finer needle, such as a 30 gauge needle, can be used.

First carpometacarpal and scaphotrapezotrapezoidal (STT) OA of the thumb may coexist, with tenderness at the proximal joint line. If unsure of the main source of pain, inject the more distal joint first to avoid confusion from a possible anaesthetic block of surrounding cutaneous nerves when performing CMC Joint injection .

References

1. Hazani R, Engineer NJ, Elston J, Wilhelmi BJ. Anatomic landmarks for Basal joint injections. Eplasty. 2012;12:e2. Epub 2012 Jan 18. PMID: 22276223; PMCID: PMC3261775.
2. Day CS, Gelberman R, Patel AA, Vogt MT, Ditsios K, Boyer MI. Basal joint osteoarthritis of the thumb: a prospective trial of steroid injection and splinting. J Hand Surg Am. 2004 Mar;29(2):247-51. doi: 10.1016/j.jhsa.2003.12.002. PMID: 15043897.
3. Helm AT, Higgins G, Rajkumar P, Redfern DR. Accuracy of intra-articular injections for osteoarthritis of the trapeziometacarpal joint. Int J Clin Pract. 2003 May;57(4):265-6. PMID: 12800455.
4. Umphrey GL, Brault JS, Hurdle MF, Smith J. Ultrasound-guided intra-articular injection of the trapeziometacarpal joint: description of technique. Arch Phys Med Rehabil. 2008 Jan;89(1):153-6. doi: 10.1016/j.apmr.2007.07.048. PMID: 18164346.
5. Mandl LA, Hotchkiss RN, Adler RS, Ariola LA, Katz JN. Can the carpometacarpal joint be injected accurately in the office setting? Implications for therapy. J Rheumatol. 2006 Jun;33(6):1137-9. PMID: 16755661.