Casting light on the overlooked trigger point of the interosseous muscles in metatarsalgia: insights and treatment strategies
Article information
We read the article "A problem-based approach in musculoskeletal ultrasonography: central metatarsalgia" by Son et al. [1], published in your journal, with great interest. The authors suggest that using ultrasound for diagnosing metatarsalgia can lead to more accurate and effective diagnostic and treatment outcomes. Additionally, they provide valuable information on the application of ultrasound in diagnosing various conditions, including Morton's neuroma, intermetatarsal bursitis, plantar plate injury, metatarsophalangeal joint synovitis, metatarsal fracture, and submetatarsal bursitis [1]. We agree entirely and respectfully with the authors; however, we would like to discuss the importance and treatment methods of trigger points of the interosseous muscles. These were not discussed in the article, yet they play a crucial role in the etiology of metatarsalgia.
Myofascial pain syndrome (MPS) is a prevalent condition in patients with musculoskeletal pathologies and can lead to pain in the foot region. The myofascial trigger points in the interosseous muscles can cause radiating pain along the distal portion of the affected metatarsal bone, extending from the lateral side of the finger to the dorsum (Fig. 1A) [2]. Diagnosing this condition can be challenging when the trigger points of these muscles are not considered in the differential diagnosis of metatarsalgia. Indeed, this aspect of MPS is often underdiagnosed according to the literature [3].
Anatomical considerations regarding the trigger point of the interosseous muscle and the blind technique.
A. The red area shows the most common referred pain pattern from the trigger point of the interosseous muscle; X marks the location of the trigger point. B. A photograph shows the blind technique needling position from the top view. C. A photograph shows the blind technique needling position from the side view.
The trigger points of the interosseous muscles are often not visualized using ultrasonography. The diagnosis is usually made based on the patient's anamnesis and the detection of taut bands on palpation of the muscles. Generally, eliciting a twitch response is favorable for the treatment of trigger points [4]. These trigger points can be addressed using dry needling therapy, which may be performed with either a blinded or an ultrasound-guided approach.
In the blinded technique, needling is conducted with the patient in a supine position. The patient's hip and knee are positioned in slight flexion, and the ankle in slight dorsiflexion. The flat palpation technique is used for needling. The needle is inserted perpendicularly, penetrating the skin from the dorsal region of the foot to the plantar region. A needle size of 0.16×30 mm is recommended (Fig. 1B, C) [5].
In the ultrasound-guided dry needling technique, the patient is positioned supine with the foot and ankle maintained in a neutral position. The probe is then positioned axially between the metatarsal bones (Fig. 2A). Using an out-ofplane approach, the needle is advanced toward the muscle at an angle ranging from 0° to 60°. Care must be taken to avoid the dorsal metatarsal arteries during needle advancement (Fig. 2B, C). The needling process is continued until a twitch response is elicited, signifying that the trigger point has been reached [5].
Ultrasound guidance for treatment of the trigger point of the interosseous muscle.
A. In the ultrasound-guided approach, the ultrasound probe is placed and needling is performed in the appropriate position. B. The metatarsal bones and interosseous muscles are visualized. C. The metatarsal arteries are visualized and avoided. MT, metatarsal bone; DI, dorsal interosseous muscle; PI, dorsal interosseous muscle; DMA, dorsal metatarsal artery.
The myofascial trigger points of the interosseous muscle can lead to metatarsalgia and may be treated using either the blind technique or ultrasound guidance. This letter aims to highlight the significance and treatment algorithm of interosseous trigger points in the foot. Clinicians should include the myofascial trigger points of the interosseous muscle in the differential diagnosis of metatarsalgia.
Notes
No potential conflict of interest relevant to this article was reported.