Radioulnar (distal) joint (art. radioulnaris distalis).

Radioulnar (distal) joint (art. radioulnaris distalis).

Classification. It is a cylindrical, uniaxial joint.

Structure.

The joint
is formed by the articulation of the articular circumference of the head of the ulna and the ulnar notch of the radius.
The distal radioulnar joint is separated from the wrist joint by a triangular-shaped disc. The capsule and ligamentous apparatus are common to the wrist joint. Functions

.
The proximal and distal radioulnar joints together form a combined cylindrical (rotator) joint: the radius rotates around the ulna. Movements in these joints are carried out simultaneously around the vertical axis (pronation - supination).
Radiocarpal joint (art. radiocarpea) – fig. 7.

Classification. The structure of the joint is complex. The shape of the articular surfaces is elliptical with two axes of movement.

Structure.

The joint
is formed by the carpal articular surface of the radius, the articular disc and the articular surfaces of the carpal bones: scaphoid, lunate, triquetrum.
The capsule is attached along the edge of the articular surfaces, capturing the radius, ulna and bones of the proximal row of the wrist. Strengthened by ligaments: carpal collateral radial and ulnar, radiocarpal palmar and dorsal (ligg. collaterale carpi radiale et ulnare, radiocarpeum palmare et dorsale).

Functions

.
Movements in the joint around the frontal (flexion and extension of the hand) and sagittal (abduction and adduction of the hand) axes.

Rice. 7. Joints and ligaments of the hand. Frontal cut: 1 - radius bone, 2 - radiocarpal joint, 3 - radial collateral ligament of the wrist, 4 - midcarpal joint, 5 - intercarpal joint, 6 - carpometacarpal joint, 7 - intermetacarpal joint, 8 - interosseous intercarpal ligaments , 9 – collateral ulnar ligament, 10 – distal radioulnar joint, 11 – articular disc, 12 – ulna.

Joints of the hand - fig. 8.

Midcarpal joint (art. mediocarpea). The joint is formed by the articular surfaces of the first and second rows of carpal bones. Complex, closer to elliptical in shape. The ligamentous apparatus and, in most cases, the capsule are common with the wrist joint.

Intercarpal joints (artt. intercarpeae) are located between the individual bones of the wrist, flat, inactive.

Carpometacarpal joints (artt. carpometacarpeae) are formed by the articular surfaces of the second row of carpal bones and the articular surfaces of the bases of the metacarpal bones. The carpometacarpal joints of the II-V fingers are closer to elliptical in shape and have little mobility.

Rice. 8. Connections of the bones of the hand, palmar surface: 1 – ulna, 2 – distal radioulnar joint, 3 – ulnar collateral ligament of the wrist, 4 – pisiform bone, 5 – hook of the hamate, 6 – carpometacarpal palmar ligament, 7 – metacarpal palmar ligaments, 8 - deep transverse metacarpal ligaments, 9 - metacarpophalangeal joint, 10 - interphalangeal joints, 11 - deep digital flexor tendon, 12 - superficial digital flexor tendon, 13 - carpometacarpal joint of the thumb, 14 - capitate bone , 15 – radial collateral ligament of the wrist, 16 – palmar radiocarpal ligament, 17 – radiocarpal joint, 18 – radial bone, 19 – interosseous membrane of the forearm.

Carpometacarpal joint of the 1st finger (art. carpometacarpea pollicis)

is a simple, saddle-shaped joint.
Formed by the articular surfaces of the trapezium bone and the base of the first metacarpal bone. The capsule is attached along the edge of the articular surfaces. Functions
.
Movements in this joint are carried out around two axes: sagittal and frontal.
Around the sagittal axis - adduction and abduction of the thumb relative to the index finger, and around the frontal axis - flexion with simultaneous opposition to the other fingers and extension of the thumb. Intermetacarpal joints (artt. intercarpeae) are formed by the adjacent lateral surfaces of the bases of the II-V metacarpal bones. These joints are flat; in them there is a slight displacement of the bones relative to each other during flexion and extension of the hand.

Metacarpophalangeal joints (artt. metacarpophalangeae) are formed by the articular surfaces of the heads of the metacarpal bones and the bases of the proximal phalanges. The articular surfaces of the heads are rounded, and the articular sockets are ellipsoidal. The capsule is attached along the edge of the articular surfaces. Strengthened by ligaments: lateral, ligg. collateralia (collateral), palmar,

ligg.
palmaria (contain fibrous cartilage), deep transverse metacarpal,
lig.
metacarpea transversa profunda. Functions
.
In the joints, movements around the frontal axis are possible - flexion and extension of the fingers, around the sagittal axis - abduction and adduction of the fingers.

Interphalangeal joints (artt. interphalangeae). Classification.

Simple,
typical trochlear, uniaxial joints . Structure. Formed by the articular surfaces of the articulating phalanges (the head and base of adjacent bones participate in the formation of the joint).
The capsule is attached along the edge of the articular surfaces. The joints are strengthened by a complex of collateral and palmar (ligg. collateralia et palmaria) ligaments.
Functions
.
In the joints, movement around the frontal axis is possible - flexion and extension of the phalanges of the fingers.

Subluxation of the distal radioulnar joint

Dislocation is a complete dislocation, subluxation is a partial dislocation [3]. Subluxation occurs when the articular surfaces are partially displaced but maintain some contact with each other [4].

Clinically Relevant Anatomy

The distal radioulnar joint (DRJ) is a synovial hinge joint. A synovial hinge is a type of synovial joint. The synovial joint allows movement at the point of contact between the articulating bones. The synovial joint consists of one bone that rotates around another.

It is stabilized by internal and external mechanisms [5].

Internal stabilizers:

• Volar and dorsal radioulnar ligaments
• Triangular fibrocartilage
• Capsule
• Ulnar collateral ligament.

External stability is achieved through static and dynamic forces:

1) Dynamic stabilizers:

• Extensor carpi ulnaris
• Pronator quadratus

2) Static stabilizers:

• Soft tissue: interosseous membrane

Epidemiology/etiology

The cause of dorsal subluxation is extreme pronation and extension with a strengthened extensor ulnaris and ulnar carpal ligaments that pull the head of the ulna through the dorsal capsule.[5] The triangular fibrocartilaginous complex, avulsion and rupture of the volar radiocarpal ligament will allow this dislocation to occur.

Characteristics / Clinical picture

Dislocations are classified as acute or chronic. Acute dislocations occur in several clinical conditions [6]:

• isolated injury
• result of fractures: radial head
• distal radial
• both bones of the forearm

In isolated injuries, dorsal ulna dislocations result from overpronation, while palmar ulna dislocations result from hypersupination.

There are simple and complex types of distal radioulnar joint dislocation. Simple dislocations are repaired spontaneously or by closed means with minimal effort. Complex dislocations include irreducible or easily subluxated or dislocated cases.

Chronic instability of the distal radioulnar joint may also occur as an isolated injury or may be associated with malunion of the distal radius. Chronic instability of the distal radioulnar joint is initially dynamic, then becomes static as osteoarthritis of the joint progresses. Joint stability depends on both intact limiting ligaments and congruence of the radioulnar joint.

Diagnostic procedures

• Computed tomography (CT) [7]
• Radiography (X-ray) [8]
• Clinical examination [9]
• Radioulnar coefficient [6]

Survey

The physical examination begins with examining rotation: pronation and supination of the wrist, if rotation is limited and painful, you have 2 options [6]:

• supination is blocked by dorsal luxation
• pronation is blocked by palm dislocation

If subluxation or dislocation of the distal radioulnar joint is an isolated injury, the only apparent cause is swelling. All movements of the wrist are often painful.

Treatment [6]

Soft tissue reconstruction: surgery

Chronic instability without any impairment can be treated with soft tissue reconstruction. Therefore, there are two different reconstruction methods: extra-articular and intra-articular. Extra-articular reconstructions provide stability between the radius and ulna without opening the distal radioulnar and elbow joints. Intra-articular reconstructions restore normal triangular fibrocartilaginous ligaments.

Open or closed reduction: surgery

Another operation that can be performed is an open or closed reduction. Closed reduction must be performed under regional anesthesia to ensure adequate muscle relaxation. Closed reduction, in order to avoid concern for subluxations of the distal radioulnar joint, should be based on the direction of dislocation. Open reduction is used when closed reduction is impossible or insufficient. Associated fractures should be assessed based on their pattern.

Immobilization

Treatment of simple subluxation in the acute situation consists of immobilization in a reduced position: neutral forearm position for bidirectional instability, supination for dorsal ulnar dislocations, and pronation for volar ulnar dislocations for six weeks in an above-the-elbow cast. The position and duration of postoperative immobilization are similar to simple dislocations.

Physiotherapy

Racing [10]

Fracture braces do not cross the elbow or wrist joint and therefore allow full movement and function of all joints of the arm, including rotation of the forearm. Patients report that the custom-fitted brace is more comfortable and has a lower profile than a commercial brace. The patient typically adjusts the tension of the brace to maximize comfort and minimize instability. The voltage can be reduced to avoid over-correction of the DLLS translation.

Fracture bracing may improve the symptoms of chronic post-traumatic or post-operative instability of DLL and may be a viable alternative to medical treatment, especially for patients with lower requirements. More active patients often choose surgical stabilization rather than choosing to continue wearing a brace indefinitely.

Effect of upper limb immobilization on isometric muscle strength, movement time and triphasic electromyographic characteristics [11]

1. The strength of the forearm flexors is significantly reduced by immobilization, while the forearm extensors remain unchanged.
2. The travel time of the ballistic movements was negligible.
3. During flexion, there was a significant decrease in antagonist (triceps brachii) spike EEMG amplitude (needle electromyography), and there was a significant decrease in agonist peak EEMG amplitude and agonist second burst EEMG amplitude during flexion, indicating an overall decrease in the amount of muscle electrical activity. During extension, there was a significant decrease in the amplitude of the iEMG peak of the agonist and the amplitude of the iEMG peak of the antagonist.

The focus of rehabilitation should be on preventing muscle atrophy by blocking the decrease in neuromuscular activity associated with limb immobilization. Although this focus may not eliminate all atrophy associated with injury and subsequent immobilization, it can provide significant reduction, resulting in significant savings in disability and rehabilitation time.

Low-volume muscular endurance and strength training during 3 weeks of forearm immobilization were effective in preventing functional decline [12].

They observed a decrease in muscle function after 3 weeks of forearm immobilization. However, low-volume endurance and strength training (about 2 minutes per session) reduced the magnitude of the decline in muscle function caused by immobilization. This low volume workout may be suitable for older cases.

Brief muscular endurance and strength training: First, an intermittent isometric hand squeeze exercise with a maximum voluntary contraction of 70% for 2 seconds with a 2 second rest interval was repeated 10 times. A dynamic handgrip exercise was then performed with a maximum voluntary contraction of 30% at a rate of 1 repetition per 1 second until exhaustion.

Physiotherapy for immobilization with plaster [13]

After immobilization, patients often suffer from decreased cardiovascular performance, muscle strength, and range of motion of the immobilized limb. Physical therapy can reduce recovery time, can allow the patient to quickly and safely return to normal activities, can improve function, and reduce the risk of future injury.

Cardio or aerobic exercise may be reduced if your immobilized limb results in decreased physical activity. To improve your cardiovascular health, a physical therapist can design a program tailored to your needs and injuries.

About 10 days after immobilization, muscle atrophy, or loss of muscle strength and size, begins to occur. To reduce atrophy, a physical therapist will often prescribe isometric exercises. It improves muscle strength and slows down muscle atrophy.

During 6-8 weeks of immobilization, muscle tissue and other connective tissues not only weaken, but can also tighten and limit normal movement. The immobilized limb is rigid and stiff, depending on the duration of immobilization. A physical therapist can help you progress faster and more safely through exercises, stretches and other treatments, helping you regain normal use of your limb and reducing the risk of damage to weakened tissue. For active people or athletes, this therapy includes higher level exercises such as plyometric, proprioceptive and sports training.

Sources

1. Pürisa H, et al. Ligament reconstruction using the Fulkerson-Watson method to treat chronic isolated distal radioulnar joint instability: short-term results. Acta Orthop Traumatol Turc. 2011;45(3):168-74.
2. Youtube. Distal Radioulnar Joint Subluxation/Dislocation. https://www.youtube.com/watch?v=MgwMXK_MQ8Y.
3. Medical dictionary. Subluxation. https://www.medterms.com/script/main/art.asp?articlekey=5581fckLRGrades of recommendation: A strong evidence (book but there are references in the text)
4. World Health Organisation, The WHO manual of diagnostic imaging. Subluxation distal radioulnar joint.https://whqlibdoc.who.int/publications/2002/9241545550_eng.pdf.
5. Tsai PC and Paksima N. The Distal Radioulnar Joint. Bulletin of the NYU Hospital for Joint Diseases 2009;67(1):90-6. https://www.ncbi.nlm.nih.gov/pubmed/19302063.
6. Wheeless' Textbook of Orthopedics. https://www.wheelessonline.com/ortho/radial_ulnar_joint_instability.
7. Lo IK, et al. The radioulnar ratio: a new method of quantifying distal radioulnar joint subluxation. J Hand Surg Am. 2001 Mar;26(2):236-43. https://www.ncbi.nlm.nih.gov/pubmed/11279569.
8. Wechsler RJ, et al. Computed tomography diagnosis of distal radioulnar subluxation. Skeletal Radiol. 1987;16(1):1-5. https://www.ncbi.nlm.nih.gov/pubmed/3823954.
9. Watanabe A., et al. Ulnar-sided wrist pain. II. Clinical imaging and treatment. Skeletal Radiol. September 2010; 39(9): 837–857. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2904904/?tool=pmcentrez.
10. Millard GM et al. Functional bracing for distal radioulnar instability joint. J Hand Surg Am. 2002 Nov;27(6):972-7.
11. Vaughan VG. Effects of Upper Limb Immobilization on Isometric Muscle Strength, Movement Time, and Triphasic Electromyographic Characteristics. Phys Ther. 1989 Feb;69(2):119-29.
12. Matsumura M. et al. Low-volume muscular endurance and strength training during 3-week forearm immobilization was effective in preventing functional deterioration. Dyn Med. 2008 Jan 15;7:1.
13. William L., and Mullennax JA Physical Therapy for Cast Immobilization. Columbus, Georgia. https://www.hughston.com/hha/a_14_2_3.htm.