What Is the Triangular Fibrocartilage Complex?

Liu Bo	(Deputy Chief Physician)	Beijing Jishuitan Hospital Hand Surgery
Chen Shanlin	(Deputy Chief Physician)	Beijing Jishuitan Hospital Hand Surgery
Tian Guanglei	(Chief physician)	Beijing Jishuitan Hospital Hand Surgery

Western Medicine Name: Triangular fibrocartilage complex injury

Affiliated Department: surgical-

Triangular fibrochondral complex injury

Triangular fibrocartilage complex (TFCC) refers to a group of important structures on the ulnar side of the wrist, including joint discs, meniscus homologues, volar and dorsal distal ulnar radial ligaments, and ulnar extensor carpal tendon sheath deep , Ulnar joint capsule, ulnar menstrual ligament and ulnar triangle ligament. The volar and dorsal distal ulnar radial ligament includes superficial and deep fibers, and the two layers converge at the radial attachment. The superficial part surrounds the articular disc and stops at the ulnar styloid process, but there is no clear-cut stop. The deep side palmar and dorsal fibers converge near the near-end point to form a joint tendon that stops at the depression of the base of the ulnar styloid process, which is also the ulnar attachment point of the ulnar ligament. This group of composite structures is anatomically fused but functions differently. The main functions of TFCC are (1) the ulnar extension of the articular surface of the distal radius, covering the ulnar head; (2) conducting the axial stress between the ulnar-wrist joints, and absorbing part of the load; (3) forming the radius and the distal end of the ulna. Elastic connection to provide rotational stability; (4) Provide support to the ulnar side of the wrist joint. The complex anatomy and multiple functions of the TFCC make it vulnerable to trauma and degeneration ^[1] .

Classification of triangular fibrocartilage complex injury diseases

The most commonly used type for triangular fibrocartilage complex injury is the Palmer type. The classification is divided into traumatic (type I) and degenerative (type II) injuries, which are instructive for treatment, so it is important to understand the Palmer classification ^[2] .

Triangular fibrocartilage complex injury type

Acute and traumatic injuries are divided into four subtypes according to the location of the injury. Type IA injury refers to the damage to the central blood supply area, which cannot usually be repaired directly; Type IB (ulnar avulsion) refers to the avulsion of TFCC from the attachment point of the ulnar side, sometimes combined with ulnar styloid fracture; Type IC (ulnar side) Distal) refers to the injury involving the TFCC palmar attachment site or the distal ligament of the ulnar wrist joint, which can be repaired; the type ID (radial avulsion) injury site is at the TFCC radial attachment point, with or without radial sigmoid Notch fracture.

Triangular fibrocartilage complex injury type

The degenerative TFCC injuries all involve the central part, and are divided into five stages A to E according to the presence or absence of TFCC perforation, softening of the lunar and ulnar cartilage, lumbar triangular ligament damage, and degenerative carpal arthritis. Most of these pathological changes are secondary to ulna impact. Generally speaking, type II injuries cannot be repaired by surgery.

According to the TFCC injury time classification, acute injury refers to the injury time less than three months from the repair time. Compared with the healthy side, it can recover more than 80% of the grip strength and joint mobility, and its prognosis is better than subacute (three months to One year) and chronic injuries (more than one year). TFCC subacute injury can also be repaired directly, but the general strength will be reduced. Occasional chronic injuries can also be repaired, but the results are not satisfactory compared to acute injuries. It is estimated that the cause is related to the pulling of ligaments and degeneration of fibrocartilage edges. Chronic injuries usually require ulnar shortening and / or TFCC debridement.

Injury mechanism of triangular fibrocartilage complex

TFCC injury can occur when the hand is supported by a fall. At this time, the wrist joint is subjected to axial stress at the position of the wrist extension and pronation. Other mechanisms of injury include greater rotational violence or stretched violence. Common causes of injury include: (1) forces on the ulnar side of the wrist of tennis, golf, badminton, and other athletes, and rapid twisting activities; (2) the driver was subjected to rotational tension while holding the steering wheel in a car accident; (3) with a person The wrist was violent during the scuffle; (4) The weight was accidentally lifted or the wrist was strained. Because the TFCC structure is hidden in a small space of the ulnar wrist joint, the pain and swelling symptoms at the time after the injury may not be particularly obvious. Patients often mistakenly think that it is just a common wrist sprain, which often delays consultation and treatment of the injury. Injuries that fall to the ground are often accompanied by more obvious injuries such as distal radius fractures. TFCC injuries are also easily overlooked or missed at the first visit. Dr. Lindau and colleagues found that 39 of the 51 patients with displaced distal radius fractures had TFCC tears, and that the infraulnar radial joint instability was common at the 1-year follow-up after injury ^[3] .

Clinical manifestations of triangular fibrocartilage complex injury

Patients usually have the above-mentioned typical medical history, seeing the doctor because of pain in the ulnar side of the wrist and the popping of the wrist during rotation. Symptoms of TFCC injury usually include diffuse, deep pain or soreness on the ulnar side of the wrist, and sometimes a burning sensation. It usually radiates to the back and rarely to the palm. Pain can also be induced when holding an object hard, resulting in reduced grip. These symptoms are exacerbated by ulnar deviation, excessive wrist extension, and forearm rotation. Patients often complain of pain on the ulnar side of the wrist when doing wrist rotation, making it difficult to twist towels, drive a car, and use a spoon. Many patients experience pain on the ulnar side of the wrist when straddling a bed or chair armrest, but this symptom is not a specific diagnostic indicator.

Diagnosis and differential diagnosis of triangular fibrocartilage complex injury

TFCC traumatic and degenerative injuries cannot be distinguished by symptoms. For whatever reason, increased wrist stress before or after pronation can cause ulnar pain in the wrist. Therefore, Palmer classification is based on the cause of the injury, not on symptoms. In fact, type I injuries are mostly caused by hyperextension falls or sudden stress in the pronation of the wrist and / or ulnar deviation, while the history of type II injuries is mostly hidden and chronic with no history of acute trauma.

For TFCC damage, physical examination is a very valuable assessment method. Acute TFCC injury is usually associated with ulnar swelling of the wrist. The sensitivity and specificity of ulnar head depression in diagnosing discontinuity of ulna head recession and / or tear of ulnar triangle ligament were 95% and 86%, respectively. The TFCC squeeze test may be positive, that is, pain occurs when axial stress is applied when the ulnar scale is off. Check the stability of the distal ulnar radial joint in the pronation and supination position of the forearm, and check whether the piano key sign of the ulnar head is positive. If combined with tearing of the lunar triangle ligament, it may be accompanied by local tenderness of the injury and a positive shear test of the moon triangle. Stabilize the radius and passively move the ulna. If the degree of slippage increases relative to the radius ulna, it indicates that the distal ulnar and radial joint (DRUJ) is unstable. Since the slip of the joint varies depending on the position of the forearm and the individual, the examination should be performed in all positions of the forearm and compared with the contralateral side.

Imaging examinations begin with standard posterior anterior and lateral radiographs. Further shooting of pronation fists can observe static and dynamic ulna variation. Although X-rays cannot directly show soft tissue lesions, some indirect information can be obtained, such as ulnar variation, the condition of the inferior ulnar radial joint, and whether there is a ulnar styloid process or a fracture of the distal radius. And when there is no or positive mutation in the ulnar bone, it is indirectly proved that the ulnar carpal bone stress is too large, and the method of reducing the load should be considered during treatment.

CT is a common imaging method used to check for DRUJ instability. But the conclusion must be combined with clinical examination and avoid overdiagnosis.

With the improvement of sensitivity, specificity and accuracy, in recent years, magnetic resonance imaging (MRI) has become the main method for the diagnosis of TFCC. However, the effectiveness of MRI in the diagnosis of localized TFCC injury still depends on the improvement of image quality and the experience of readers. If the injury is considered degenerative and combined with ulna impact syndrome (type II injury), MRI examination can reveal edema on the ulnar side of the moon. In general, MRI examinations can provide the surgeon with valuable information before an incision or wrist arthroscopy is needed.

Wrist arthroscopy is the gold standard and the best method for diagnosing TFCC injuries, because the best method for arthroscopic examination can more accurately diagnose the type and severity of tears. This minimally invasive technique allows direct observation of cartilage discs under strong light and magnification, and probes can also be used to probe the tension of the cartilage discs. Normal probes are used to probe normal cartilage discs, the tension of the cartilage discs is tense, and in patients with tears around the periphery of the cartilage discs, the tension of the cartilage discs disappears and local accumulation occurs. In addition, arthroscopy is very effective in identifying Palmer type IA and ID injuries (including whether the ulnar and radial dorsal ligaments of the lower ulnar joint are involved), and the treatment of these two injuries is completely different. Arthroscope also has the function of diagnosis and treatment at the same time, irreparable and degenerative TFCC damage can be debrided, and repairable damage can be repaired at the same time.

Previously, carpal angiography was an important method for judging TFCC injury, but later it was found that the results were poorly correlated with the clinic and was questioned. Asymptomatic wrist joints, including young people, have a high incidence of perforations. In addition, arthroscopy is less sensitive than arthroscopy. With the increasing use of non-invasive magnetic resonance imaging and arthroscopy, the use of arthrography has decreased significantly.

When the patient complains of wrist ulnar pain, other causes should be ruled out first, such as ulnar extensor carpal tendonitis or subluxation, menstrual triangle ligament injury, leg triangle arthritis, and ulnar wrist impact syndrome. The elimination of the above causes can be carried out through careful physical examination and imaging examination, and selective local closed injection can be used to help identify if necessary. For intra-articular lesions, such as meniscus ligament injury or ulnar-carpal impingement syndrome, diagnostic wrist arthroscopy facilitates direct and accurate diagnosis and evaluation of the lesion.

Triangle fibrocartilage complex injury treatment

There are many ways to treat TFCC injuries, and what kind of treatment needs to be taken depends on the following factors: whether there is wrist pain (including mechanical irritation caused by the injury or persistent joint pain caused by synovitis), whether it is accompanied by fracture or fracture deformity healing And whether there is instability of the distal ulnar radial joint.

If the patient's medical history and examination suggest TFCC injury, the X-ray examination is normal, and there is no evidence of clinical instability. The acute phase can be fixed with long arm casts or braces for 4-6 weeks. Occasionally, physical therapy can be applied. If the symptoms do not resolve after the fixation, further tests such as magnetic resonance imaging and arthroscopy are required. TFCC injuries that have been ineffective for 2-3 months have been indicated for arthroscopic surgery.

Another indication for surgery is instability of the distal ulnar radial joint. If the patient has radiological or clinical instability, early evaluation of arthroscopy and repair should be considered.

The method of surgical treatment depends on the type of injury. In general, for traumatic central injury, if the injury does not involve the dorsal metacarpal ligament, it will not affect the function of TFCC, and arthroscopic debridement can obtain a good therapeutic effect. TFCC peripheral tears can be repaired under arthroscopy. If factors of ulnar carpal impact are combined, surgical treatment is required at the same time. For degenerative TFCC injury, it is mostly secondary to ulna impact. Generally speaking, this type of injury cannot repair the TFCC's own injury through surgery, but it can obtain good results by treating the causes of degeneration. Current surgical methods include ulnar shortening, arthroscopic or incision wafer surgery, degenerative TFCC, softened cartilage, torn ligaments, scarring of the joint capsule, and debridement of the synovium.

Prognosis of triangular fibrocartilage complex injury

The application of arthroscopy has changed the status and results of TFCC injury treatment. Pain in the ulnar side of the wrist, even the rare type I injuries, can be effectively treated with the help of arthroscopy. Small surgical scars and short braking time after surgery can give patients the opportunity to return to work earlier.

Acute TFCC injury means that the injury time is less than three months from the repair time. Compared with the healthy side, many cases can have the opportunity to recover more than 80% of the grip strength and joint mobility, and its prognosis is better than subacute (three months to one year) And chronic injuries (more than one year). TFCC subacute injuries can sometimes be repaired directly, but the strength generally decreases. In rare cases, chronic injuries can also be repaired, but the results are unsatisfactory compared with acute injuries. It is estimated that the cause is related to the pulling of ligaments and the degeneration of fibrocartilage edges. Therefore, for chronic injuries, ulnar shortening and / or TFCC debridement are usually required. If symptomatic chronic distal ulnar radial joint instability is involved, some patients also need to perform reconstruction of the distal ulnar radial ligament ^[4] .

Rehabilitation of triangular fibrocartilage complex injury

If only arthroscopic TFCC debridement is performed, braking is generally not required after surgery. If arthroscopic TFCC repair is performed, the wrist should be worn for 4-6 weeks after the wrist is in a neutral elbow brace. After 6 weeks, he started to gradually perform passive joint exercise exercises and gentle active strength training. After about 10-12 weeks, he gradually resumed daily activities and generally resumed physical activities after 6 months.