Effectiveness and Safety of Triangular Fibrocartilage Complex Injection Regarding Anatomical Landmarks: A Cadaveric Study

Abstract

Background  Triangular fibrocartilage complex (TFCC) injections can be applied using anatomical landmarks or under the guide of ultrasound (US). US is not always available, and the physician may rely on the anatomical landmarks.

Objective  The study aims to evaluate the effectiveness and safety of TFCC injection with anatomic landmarks.

Methods  Forty wrist specimens from cadavers were randomly assigned to four rapid blue stain injection groups as follows: Group A: perpendicular to skin with 5 mm depth; Group B: perpendicular to skin with 10 mm depth; Group C: 45-degree angulation to skin surface, oriented from proximal to distal with 10 mm depth; and Group D: 45-degree angulation to skin surface, oriented from distal to proximal with 10 mm depth. TFCC specimens were excised and evaluated with microscopy, and adjacent neurovascular structures were checked for any injury.

Results  Injections in group A were more accurate than others, in which 8/10 injections were successful. Group C injections were least accurate in that only 4/10 were successful. The other remaining groups (groups B and D) revealed similar results (5/10 were successful). However, statistical analyses did not show any significant difference ( p -value = 0.35). No injury to neurovascular structures was seen.

Conclusion  Needle placement perpendicular to skin with 5 mm depth and just medial to ulnar styloid can be used as an accurate method of palpation-guided technique for TFCC injections.

Triangular fibrocartilage complex (TFCC) is an essential stabilizer of ulnocarpal and distal radioulnar joint in supination/pronation and axial load to the wrist. TFCC consists of various components, including articular disc, meniscus homologue, and ulnocarpal, dorsal, palmar radioulnar, ulnar collateral, ulnotriquetral, and ulnolunate ligaments. ¹ Injuries to TFCC whether traumatic or degenerative may lead to pain and instability of the wrist. ^{2 3} The first-line management for TFCC injuries is conservative treatments, including rest, immobilization, analgesics, and physiotherapy. ⁴ If the patient does not respond to conservative treatment, invasive modalities such as corticosteroid injection or surgery are recommended. ⁵ Injection in TFCC similar to other regions in the musculoskeletal system can be applied using anatomical landmarks or ultrasound (US) guide. ^{6 7} Some believe that relying on anatomical landmarks is not a precise method due to lack of direct visualization of the structures. ⁸ However, in some outpatient clinics, US is not available, and the physician may rely on the anatomical landmarks. To our best knowledge, no precise descriptive technique based on anatomical landmarks and needle direction has been published. In the present cadaveric study, we evaluated the effectiveness and safety of TFCC injection with anatomic landmarks.

Materials and Methods

Forty wrist specimens from 20 fresh male cadavers, aged 20 to 70 years, without any noticeable scar or deformity in the wrist, were obtained. Since body mass index (BMI) could affect the depth of skin, we did not include grossly fat or lean cadavers. The procedures, including injection and dissection of the specimens, were performed by an orthopaedic surgery resident. The experiments were performed following Human Tissue Storage and Use Policy. The experiment was reviewed and approved by the ethical committee of Shiraz University of Medical Sciences. Informed written consent was obtained from the first-degree relative of the deceased people.

Injection Technique

We positioned the forearms in pronation and identified the tip of ulnar styloid bone at the medial aspect of the wrist as the landmark for injection ( Fig. 1 ). We injected 0.1 cc of methylene blue with insulin syringe in each wrist specimen. The 40 specimens were randomly assigned to 4 groups consisting of 10 wrist specimens as follows: Group A: perpendicular to skin with 5 mm depth; Group B: perpendicular to skin with 10 mm depth; Group C: 45-degree angulation to skin surface, oriented from proximal to distal with 10 mm depth; and Group D: 45-degree angulation to skin surface, oriented from distal to proximal with 10 mm depth.

Fig. 1.

The tip of ulnar styloid bone identified as an anatomical landmark for methylene blue injection in triangular fibrocartilage complex.

Histopathologic Evaluation

After injection, the wrists were dissected, and TFCC specimens were excised and fixed in formalin. Also, adjacent neurovascular structures were checked for any injury during the injection. Cross-section samples of TFCC specimen were provided and stained with hematoxylin-eosin. Color changes were observed under a microscope, and recorded with Olympus DP12 Digital Camera system (Olympus Optical, Tokyo, Japan). This observation was double-blinded and performed by a pathologist. Those specimens in which the blue color stained the TFCC complex were considered as a successful injection ( Fig. 2 ).

Fig. 2.

High-power microscopy of the negative ( A ) and positive ( B ) staining of triangular fibrocartilage complex samples with methylene blue.

Statistical Analysis

Data are expressed as mean ± standard deviation. Statistical significance between groups was analyzed by the chi-square test, using SPSS version 11.5 (SPSS, Chicago, Illinois). A p -value <0.05 was considered to be statistically significant.

Results

Forty wrist specimens from 20 cadavers underwent dissection after TFCC injection. The mean age of the recruited cadavers was 48.8 ± 12.9 years, ranging from 25 to 70 years ( Table 1 ). Sixteen (80%) cadavers were male, and the other four (20%) were female. In the gross exploration of the injection site, no injury to neurovascular structures was seen regardless of the method of injection. Injections in group A (perpendicular and 5 mm depth) were more accurate than others, in which 8/10 injections were successful. The group C (45-degree angulation proximal to distal and 10 mm depth) injections were least accurate in that only 4/10 were successful. The other remaining groups (groups B and D) revealed similar results (5/10 were successful). Despite variation in the success rate of injections in different groups, statistical analyses did not show any significant difference ( p  = 0.35).

Table 1. Baseline characteristics and positive triangular fibrocartilage complex staining following dye injection.

Variable	Mean (SD)	p -Value
Age	48.8 (12.9)
Sex ( n  = 20)	n (%)
Male	16 (80)
Female	4 (20)
Positive TFCC staining ( n   = 40)
Group A, n  = 10	8 (80)	0.35
Group B, n  = 10	5 (50)
Group C, n  = 10	4 (40)
Group D, n  = 10	5 (50)

Abbreviations: TFCC, triangular fibrocartilage complex; SD, standard deviation.

Note: Group A, perpendicular and 5 mm depth; Group B, perpendicular and 10 mm depth; Group C, 45-degree angulation proximal to distal and 10 mm depth; Group D, 45-degree angulation distal to proximal and 10 mm depth.

Discussion

Steroid injection can be used as a nonoperative method in the treatment of TFCC injuries. Despite the superficial lying of ulnocarpal joint, precise needle placement and injection into TFCC can be challenging due to small space, variable anatomy, and injection method. Initially, some studies used fluoroscopy to increase the accuracy of injections. Nevertheless, fluoroscopy is expensive, requires cumbersome equipment, and also exposes the patient and physician to ionizing radiation. ⁹ On the contrary, recently, US has been used as a popular and precise utility and without the risk of radiation for guided intra-articular injections. ¹⁰ However, US is expensive and also needs expert physician. Therefore, intra-articular injections are often performed without US guidance. Familiarization with the ulnocarpal anatomical landmarks is an essential requirement for proper and effective injection. Incorrect injection not only can lead to ineffective treatment but also may cause inadvertent complications. ¹¹ However, previous studies on palpation-guided intra-articular injections have revealed that the accuracy rate was low compared with radiographic or sonographic-guided methods. ¹² Contrarily, our results showed 80% accuracy rate. The best explanation is that the previously reported studies had no formal and precise palpation technique, and correct placement of the needle. Nam et al ⁸ evaluated palpation- versus US-guided techniques in wrist injections. They showed that sonography-guided injections are more accurate than palpation-guided technique. Majority of previous studies suggests US-guided injections due to its higher accuracy. ^{13 14 15 16} However, some studies revealed that despite the greater accuracy rate of sonographic-guided injections versus palpation-guided method, there are no ^{17 18 19} or modest ^{20 21} differences in their clinical outcomes. To our best knowledge, no formal and precise description for a palpation-guided technique for TFCC injections has been published. Our study presents the first published cadaveric description of a palpation-guided technique for TFCC injection. Our results suggest that the best technique for effective TFCC injection is to place the needle perpendicular to the skin, just medial to ulnar styloid with 5 mm depth. There are some limitations in this study. First, the number of cases was relatively small. Second, we did not evaluate the cadavers for possible needle barriers such as osteophytes or ulnar styloid nonunions. Third, all the injections were performed in medium-sized cadavers. Fourth, this work was done on cadavers, so the results may not exactly be representative of the clinical outcome. We selected the cadavers from same sex and with same BMI and excluded the cadavers in extremes of age (older than 70 and younger than 17 years) to make our specimens more similar. Also, we excluded those wrist specimens with gross pathology or scar at their upper extremities. However, minor variations may still be preset among the specimens and it was inevitable. The strong point of this study is that this is the first study that evaluated different methods of palpation for TFCC injection.

Conclusion

Needle placement perpendicular to skin with 5 mm depth and just medial to ulnar styloid can be used as an accurate method of palpation-guided technique for TFCC injections.

Funding Statement

Funding The project was financially supported by Shiraz University of Medical Sciences.