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Novel Therapeutic Approach for Extensor Digiti Minimi Tendon Traction in Chronic Ulnar-Sided Wrist Pain Diagnosed as Triangular Fibrocartilage Complex Injury: A Case Report
Korean J Sports Med 2023;41:250-255
Published online December 1, 2023;  https://doi.org/10.5763/kjsm.2023.41.4.250
© 2023 The Korean Society of Sports Medicine.

Cheol-Jung Yang1, Jeong Won Seong2

1Department of Orthopedic Surgery, Borntouch Orthopaedic Clinic, Seoul, Korea, 2Department of Family Medicine, Sarang Clinic, Jinju, Korea
Correspondence to: Jeong Won Seong
Department of Family Medicine, Sarang Clinic, 477 Jinnyangho-ro, Jinju 52686, Korea
Tel: +82-2-442-0087, Fax: +82-2-428-0087, E-mail: tongsaresearch@gmail.com
Received October 10, 2023; Accepted October 20, 2023.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
 Abstract
Ulnar-sided wrist pain is common in sports medicine and orthopedics, typically diagnosed as a triangular fibrocartilage complex (TFCC) injury. We present a case study involving a 22-year-old male who has been experiencing chronic left wrist pain for the past 9 months. He was diagnosed with a TFCC injury and received conservative treatment. Surgery was recommended if the pain persisted after 9 months. He exhibited tenderness in the dorsal radioulnar joint region and the proximal one-third portion of the extensor digiti minimi (EDM) muscle. At a tendon traction point (TTP) over the EDM muscle, 4 mL of isotonic saline was injected at presentation, 1 and 3 weeks later. The pain significantly improved, and he did not experience any adverse effects or worsening of his symptoms during the 13-month follow-up. The injection therapy at the TTP of the EDM can be considered in chronic unhealed ulnar-sided wrist pain, including TFCC injury, to release the tightly contracted EDM muscle.
Keywords : Ulnar-sided wrist pain, Triangular fibrocartilage complex, Extensor digiti minimi, Tendon traction point
Introduction

Ulnar-sided wrist pain is a common issue in sports medicine and orthopedics, particularly within the realm of upper extremity pain1. In sports activities, the wrist is subjected to repetitive stresses or acute trauma, which can lead to ulnar-sided wrist injuries, becoming a significant source of disability for many athletes.

The traditional approach to musculoskeletal pain often centers on radiological abnormalities, but many patients report discomfort without any abnormal findings on radiological examinations. In the wrist, ulnar-sided wrist pain may be caused by triangular fibrocartilage complex (TFCC) injury, lunotriquetral ligament injuries, and ulnar impaction syndrome1. Nevertheless, functional tendon traction of a muscle can lead to musculoskeletal pain either at the point of insertion on the periosteum or through repeated friction within the surrounding tissue, potentially leading to inflammation2,3. We termed the concept mentioned above as the tendon traction point (TTP). Based on our clinical experience, we are aware that TTP can induce various pain symptoms3.

The volar and dorsal radioulnar ligaments of TFCC are continuations of the dorsal muscular layers, including the extensor digiti minimi (EDM) tendon4,5. Unhealed ulnar-sided wrist pain diagnosed as TFCC injury is possibly caused by the EDM tendon traction syndrome; the tightly contracted EDM tendons can act as TTP and contract TFCC, causing ulnar-sided wrist pain.

In this report, we present a case of chronic ulnar-sided wrist pain diagnosed as a TFCC injury, which was effectively treated with three injections of isotonic saline into the TTP of the EDM muscle. The application of the TTP concept led to the improvement of chronic ulnar-sided wrist pain by releasing the tightly contracted EDM muscle.

The patient provided written informed consent for the publication of this case report and the accompanying images. This case study was approved by the Institutional Review Board of the Armed Forces Medical Command (AFMC) in Seongnam, South Korea (No. AFMC-18072-IRB-18-060).

Case Report

A 22-year-old healthy man (176 cm, 72 kg) with a complaint of left ulnar-sided wrist pain persisting for 9 months visited the orthopedic outpatient department clinic. He was a soldier and frequently engaged in dumbbell exercises and lifting heavy objects as part of his duties. The ulnar-sided wrist pain was exacerbated when he gripped and pronated his wrist while handling heavy objects. Upon physical examination, his wrist displayed a normal range of motion, but tenderness was noted in the dorsal radioulnar joint (DRUJ) region. There were no clicking or popping sensations with wrist motion, and DRUJ instability was not observed. Plain wrist radiography revealed no abnormal findings, while magnetic resonance imaging (MRI) indicated a partial tear of the TFCC proximal lamina (Fig. 1). Nine months ago, he was diagnosed with a TFCC injury at an orthopedic clinic and had been undergoing conservative treatments, which included the use of nonsteroidal anti-inflammatory drugs, multiple physical therapy sessions, and a steroid injection at the painful region. However, there was no improvement in wrist pain, and surgery was recommended.

Fig. 1. Magnetic resonance imaging revealed a partial tear of the triangular fibrocartilage complex proximal lamina (arrow).

During the physical examination, tenderness was noted in the DRUJ region, and there was notably more pronounced tenderness over the proximal one-third portion of the EDM muscle when compared to the opposite side. Although the patient has been treated for TFCC injury for a long time, it has not improved. As a result, we hypothesized that the point of tenderness in the EDM was the TTP and that the tightly contracted EDM tendon stimulated the TFCC, leading to inflammation and chronic ulnar-sided wrist pain. He was subsequently diagnosed with EDM tendon traction syndrome3,4.

As a therapeutic intervention, to release the TTP within the EDM muscle, a 4 mL isotonic saline injection was administered at the proximal one-third portion of the EDM, which was the most tender region of the EDM muscle—under ultrasound guidance (Fig. 2A and B). The injection was repeated at 1 and 3 weeks after the first injection.

Fig. 2. Ultrasound-guided injection into the proximal one-third portion of the extensor digiti minimi (EDM) muscle, which was most tender. (A) Ultrasonography verified the needle’s placement within the EDM muscle (arrow, 23-gauge needle). (B) Color Doppler ultrasonography confirmed the flow of the injected isotonic saline within the EDM muscle. ECU, extensor carpi ulnaris; EDC, extensor digitorum communis.

Functional outcomes were measured using the Disabilities of the Arm, Shoulder and Hand (DASH) score and a visual analog scale (VAS). The parameters were evaluated prior to each injection, initially as a baseline assessment, and during each subsequent visit to assess the effects of the previous injection. The final assessment of outcomes took place 13 months following the initial injection, during which the patient was asked to report any adverse effects during each visit for evaluation.

Before the first injection, the baseline DASH and VAS scores were 23.3 and 5 points, respectively. One week after the first injection, those scores improved to 9.2 and 2 points, respectively, and further improved to 2.5 and 0 points, respectively, at 13 months after the first injection (Fig. 3). During the 13-month follow-up, there were no adverse effects or exacerbation of symptoms noted. At this point, the patient reported feeling comfortable with no wrist pain during dumbbell exercises and when lifting heavy objects, expressing satisfaction with the treatment results.

Fig. 3. One week following the initial injection, Disabilities of the Arm, Shoulder and Hand (DASH) and visual analog scale (VAS) scores showed improvements of 14.1 and 3 points, respectively. These improvements were further enhanced to 20.8 and 5 points, respectively, at the 13-month follow-up after the first injection. Both results exceeded their respective minimal clinically important differences and remained consistent 13 months after the first injection. The VAS scale ranges from 0 to 10, with lower scores indicating better outcomes. Outcome measurements were taken before the injection. The asterisks indicate the time of injection.
Discussion

Ulnar-sided wrist pain is common in TFCC injuries1. The TFCC consists of the triangular fibrocartilage, ulnar collateral ligament, extensor carpi ulnaris sheath, as well as the superficial and deep volar and dorsal radioulnar ligaments6. In a previous study, MRI signal enhancement at the distal wrist was more frequently associated with ulnar-sided wrist pain. This radiographic finding was present in only 32% of cases with symptomatic TFCC tears.

In a retrospective review of 908 patients, the reported sensitivity and specificity of MRI in diagnosing TFCC tears ranged from 73% to 76% and 41% to 44%, respectively7. This finding suggests that it may be difficult to differentiate corresponding structural sources of ulnar-sided wrist pain from unrelated incidental findings and highlights the importance of performing a detailed physical examination.

This case report is meaningful because it describes the case of refractory wrist pain on the ulnar side for 9 months in a healthy adult male who was diagnosed with TFCC injury and was successfully treated with three injections of isotonic saline into the proximal one-third portion of the EDM, the most tender region of the EDM muscle. The ulnar-sided wrist pain was treated by using the TTP concept to release the tightly contracted EDM muscle.

Seong and Kwon2 and Seong3 defined TTP as a point at which a muscle’s physically contracted tendons stimulate the periosteum at their insertion or produce repeated friction within the surrounding tissue, causing a “crackling” sound or resulting in inflammation. The surrounding tissues involve connective tissue such as retinaculum that can cause friction to tightened tendons around joints and to protruding tubercles, tuberosities, trochanters, and epicondyles. Moreover, the bursa and tendon sheaths are structures filled with synovial fluid to reduce friction in tendons. Friction in these areas results in bursitis or tenosynovitis and is characterized as inflammatory pain.

In a previous study, the volar and dorsal radioulnar ligaments of TFCC were found to be continuations of the dorsal muscular layers, including the EDM tendon4,5. In our case, we hypothesized that the tightly contracted EDM tendon stimulated TFCC, which caused inflammation and chronic wrist pain on the ulnar side. Therefore, to improve ulnar-sided wrist pain, releasing the tension within the EDM in which the TTP had formed is necessary. The injection therapy includes the intramuscular administration of isotonic saline into the muscles responsible for the pain. This approach provides a means to reach treatment points that target muscle tension, potentially leading to the resolution of the contracted EDM muscle.

In the present case, the ulnar-sided wrist pain significantly improved after three injections of isotonic saline into the TTP of the EDM muscle. The functional outcomes of DASH and VAS improved by 14.1 and 3 points and 20.8 and 5 points at 1 week and 13 months, following the first injection of isotonic saline, respectively. The DASH is a valid measure of physical function in wrist pain, and a minimal clinically important difference (MCID) of 10 points has been reported to be significant8. The VAS is a dependable and widely applicable tool for assessing pain intensity, with a reported MCID of 2 points9. The present measurement outcomes of DASH and VAS surpassed their respective MCIDs and were maintained at 13 months after the first injection.

Apart from TFCC injury, ulnar-sided wrist pain can result from various other conditions, including DRUJ instability, extensor carpi ulnaris (ECU) tenosynovitis, lunotriquetral ligament injuries, and ulnar impaction syndrome1. When a patient complains of musculoskeletal pain, the structural problems are usually focused, and surgical treatment is often recommended when conservative treatment has failed. Prior to surgical treatment, it is important to determine whether the cause of musculoskeletal pain is functional pain caused by TTP, as in this case. The proximal one-third tender region of the EDM muscle can act as the TTP and contract the TFCC, causing ulnar-sided wrist pain. The TTP can cause ulnar-sided wrist pain through pathologic isotonic contraction of the EDM muscle.

Certain studies have indicated that intramuscular isotonic saline injection for pain reduction in the control group exhibits comparable effectiveness, showing no statistically significant inferiority when compared to the experimental group, such as lidocaine injection for fibromyalgia, prolotherapy injections for chronic low-back pain, platelet-rich plasma injections for chronic rotator cuff tears, and autologous blood and corticosteroid injections for lateral epicondylitis10-13. In these studies, the observed pain improvement following the administration of isotonic saline injections was attributed to a placebo effect10-13. However, we only used isotonic saline to release TTP without using other commonly used chemical agents, such as lidocaine or steroids.

Isotonic saline was typically chosen for this study because of its affordability and favorable side effect profile. Clinical studies have suggested that the effects of muscle injection are not due to the pharmacological effect of the injected drug but due to the mechanical effect of the needle and injection14,15. Regardless of the solution used, the tightly contracted tendon of the muscle is recovered following the injection as the mechanical release of tightened tendon, not due to the chemical effect of the injected drug14,15.

Furthermore, isotonic saline is more secure and accessible than other chemical agents10,13. Several studies have also focused on the ECU muscle to alleviate ulnar-sided wrist pain with injection of the ECU muscle1,6. This study, to our knowledge, represents the first report of addressing ulnar-sided wrist pain through the resolution of TTP formation within the EDM muscle.

This report is subject to several limitations. First, this study reported the clinical findings of only one patient. Second, TTP injection treatment was not compared with other treatments. However, the significant improvement in chronic ulnar-sided wrist pain persisting for over 9 months with only a few injections highlights the importance of the TTP concept in the management of pain.

This case report highlights that releasing TTP in the EDM muscle should be considered for chronic ulnar-sided wrist pain, including TFCC injury, especially when conservative treatment has failed. Increased tension in the EDM muscle can serve as a TTP and contract TFCC, causing ulnar-sided wrist pain. Patients often complain of the most intense tenderness within the proximal one-third portion of the EDM muscle acts as TTP, and isotonic saline injection therapy into this point has a fundamental therapeutic improvement.

Conflict of Interest

No potential conflict of interest relevant to this article was reported.

Acknowledgments

This work was supported by the TongSa (Association of Pain and Function Analysis) Research Fund. The authors thank Ms. Hye-Sun Han for her invaluable technical assistance and contributions to the graphic design.

Author Contributions

Conceptualization: JWS. Writing–original draft: CJY. Writing–review & editing: CJY, JWS.

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