I. Brief development
The technique of wrist arthroscopy was developed from other large joints (knee, shoulder). 1918 Kenji Takagi applied a 7.3 mm cystoscope to observe the knee joint of a cadaver, and in 1931 he successfully observed the internal structure of the knee joint for the first time by applying a 3.5 mm arthroscope he developed and dilating the joint cavity with fluid. Since then, thanks to the hard work of many scholars such as Masaki Watanabe and John B. McGinty, the Arthroscopy Society, the International Arthroscopy Association (IAA) and the Arthroscopy Association of North America (AANA) were established. The Journal of Arthroscopic and Related Surgery was founded, and the theory of arthroscopy was developed, and the instruments and techniques were improved. In the 1980s, arthroscopic instruments and equipment underwent radical changes, and special sets of instruments were developed for specific diseases. The pointer was expanded to achieve excellent clinical results for repair and shaping of meniscal injuries and repair and reconstruction of cruciate ligaments, and the application in other joints was rapidly developed.
The application of wrist arthroscopy was first reported by Yung-Cheng Chen in 1979, but it was not until the mid-1980s that wrist arthroscopic techniques were widely accepted as a diagnostic method for the wrist. Based on the fine anatomical knowledge of the wrist, Terry L. Whipple, Gary Poehling, James Roth, and A. Lee Osterman and other scholars developed arthroscopic treatment techniques for the wrist. The use of 2.7mm, 1.9mm or even smaller 1.0mm diameter arthroscopes allows access to any joint of the hand for observation, and wrist arthroscopy has been extended to the interphalangeal joint. “However, due to the complex structure of the wrist joint, the many articular surfaces of the wrist bone, the multiple phases of motion, the small intertrochanteric ligaments, and the large variety of tissue structures such as blood vessels, nerves, and tendons around the wrist joint, the current repair techniques are mostly developed on the basis of the knee and shoulder joints, and there are problems with the operational feasibility and effectiveness of these mature techniques for the wrist joint. There are problems of operational feasibility and effectiveness, i.e. whether the current instruments can effectively reach the operating site and how to produce an effective biomechanical repair effect, so the wrist arthroscopy technology is still looking forward to greater development, and is far from reaching the realm of “comfortable operation, minimally invasive and efficient” of the current large joint repair. At present, it has only achieved some success in treating wrist synovitis, triangular fibrocartilage injury, distal radius fracture, dorsal carpal cyst, intercarpal ligament (intercarpal ligament and lunar triangular ligament) and carpal fracture (navicular fracture).
II. Special instruments and equipment for wrist arthroscopy
Compared with traditional incisional surgery, arthroscopic surgical equipment and instruments have their own special characteristics. With the understanding of joint anatomy and pathology, instruments for arthroscopy have been continuously developed, and today, arthroscopic equipment and instruments have become a widely functional surgical hardware system, which generally includes: arthroscope, surgical instruments, imaging system, power system and record storage system. The imaging and recording storage systems for wrist arthroscopy are the same as those for other large joints, but because of the delicate structure of the wrist joint and the small joint space, the arthroscope and surgical instruments used to enter and exit the joint space are more delicate and complex, and have their own special characteristics.
(A) Arthroscopy
Wrist arthroscopes are usually rigid, with diameters of 2.7 mm, 2.5 mm and 1.9 mm, and some scholars use 2.9 mm and 1.0 mm. 2.7 mm and 2.5 mm arthroscopes provide a larger field of view and are suitable for the radial carpal joint, 1.9 mm arthroscopes have a smaller field of view and are suitable for the midcarpal joint and the distal radial ulnar joint, and 1.0 mm arthroscopes are usually used for the interphalangeal joint. arthroscope is usually used for the interphalangeal joint, and arthroscopes of 2.9 mm or more are generally more difficult to access. Arthroscopic lenses have certain tilt angles, 0°, 30° and 70°. 0° and 30° lenses are mainly used to observe anterior tissues, and 70° lenses are mainly used to observe lateral and posterior tissues. By rotating the lens, the field of view can be increased and different parts of the body can be observed, but attention should be paid to the blind area in the center of rotation. At present, 30° arthroscopic lens is mostly used clinically, which has the characteristics of wide field of view, no blind area and part of the central field of view always exists when rotating, which is more in line with the surgical requirements. (Figure 1)
Figure 1 1.9 mm 30° wrist arthroscope, probe and Figure 2 Wrist traction tower (Linvatec, USA)
Arthroscopic sheath and sheath core
(II) Auxiliary equipment
1.Wrist traction stand, because the joint space of wrist joint is very narrow, it needs to perform proper traction in order to have enough operating space. Although some scholars believe that the traction state is not conducive to wrist movement and has hindrance to arthroscopic examination and surgery, the wrist arthroscopic treatment in traction state is still the mainstream at present. There are four types of traction brackets in use: the commonly used Whipple Wrist Traction Tower (Figure 2), the newly used Arc Wrist Tower from Acumed, the suspension traction bracket used as a supplemental alternative, and the finger splint traction bracket used in Europe. In the first three types, finger splint traction is used, and traction of the index and middle fingers is usually sufficient, sometimes traction of the index, middle, ring and little fingers and the thumb is required. The latter two do not have a fixed device for the forearm, the surgery is fixed by the assistant forearm, the wrist joint is more free, but the surgical assistant is more tired, can not always maintain the angle of the wrist joint, causing some difficulties for the frequent access to the arthroscope and surgical instruments; the first two are the opposite.
2, gravity perfusion system and joint irrigation pump, the gravity perfusion system of the wrist joint mainly consists of a higher can support 3-4 500ml or 1-2 3l saline plastic bag boom or bracket, each saline plastic bag between the connecting tube and the inlet pipe (usually using the general infusion tube). When using the plastic bag suspended with a height of about 2m, a maintain a certain water pressure. The infusion tube is connected to the arthroscopic sheath as the water intake. Since the wrist joint gap is very narrow and the lens is relatively close to the tissue structure, it is easy to cause blurring of the field of view, so it is more important to maintain continuous and unobstructed irrigation, and generally one or more outlets are used, and a 20-gauge syringe needle can be used. Some scholars also use joint irrigation pumps in doing wrist arthroscopy, which is better for maintaining a continuous clear view, but it is important to pay attention to the pressure and to take appropriate measures to prevent the occurrence of forearm interosseous compartment syndrome, especially when dealing with distal radius fractures.
3, light source, arthroscopic surgery are currently using cold light source lighting, for wrist arthroscopy to xenon lamp effect is better, halogen lamp can be used as an emergency, xenon lamp color temperature up to 6000k or more, can provide a clear field of view, conducive to correctly distinguish the subtle intra-articular tissue structure changes, while halogen lamp color temperature is generally below 5000k, the field of view is more dim, not conducive to long-term use.
(iii) Manual instruments.
1, probe, wrist arthroscopy using the front end of the probe is 70 ° curved, easy to enter the wrist joint, relatively thin, suitable for finger control, with directional instructions, is the most commonly used instrument. During wrist arthroscopy, the soft tissues blocking the field of view can be plucked away and the texture of the ligaments and cartilage can be probed. The tip of the probe is 1 mm in diameter and can be used to estimate the extent of injury.
2, manual cutting forceps, as with other beat arthroscopy, the manual cutting forceps used in wrist arthroscopy also have left, right curved, straight and upper and lower openings. Smaller diameter, generally 2.0mm and 2.75mm, length of 65mm and 90mm, the head has a blunt type and spade type two.
Grasping forceps, grasping forceps is a common instrument for wrist arthroscopy, used to remove the free body and some soft tissue fragments in the joint, sometimes can also pull the tissue to understand the tension, diameter of 2.0mm and 2.75mm, length of 65mm and 90mm, the head has a standard blunt round and mosquito type micro-tip two.
Small joint strippers (spatulas) and intra-articular knives, small joint strippers (spatulas) are widely used with a slightly curved head to facilitate access to the joint, 65 mm and 90 mm in length, 2.75 mm in diameter, and two types of strippers and spatulas, mainly used to loosen adhesions and remove bone fragments, and sometimes like probes to probe ligament tension and assist in the repositioning of intra-articular fractures. Like large joints, the knives are also shaped like banana knives, half-moon knives, hook knives, etc. They are protected by sheaths to prevent damage to surrounding tissues when entering and leaving the joint, and are now mostly replaced by other surgical instruments.
(iv) Power system
Arthroscopic surgery not only requires manual instruments, but also often uses electric instruments, mainly planer. The power system includes the power host, operating handle and planer head, sometimes the host can also be connected to orthopedic power instruments, and the direction and speed can be controlled by the handle or foot switch, and the handle has an outlet pipe that can be connected to the negative pressure suction device, which is conducive to the timely removal of intra-articular tissue debris and has the characteristics of wide use and easy operation. Wrist arthroscopy uses a small planing handle connected with a planing tip of about 3.0 mm in diameter, and there are different types of planing tips for synovial soft tissue cleaning, for bone cartilage cleaning and for bone resection.
The basic operation and basic anatomical knowledge of wrist arthroscopy technique
Knowledge of wrist anatomy is very important for the use of wrist arthroscopy. The production of access, lesion identification and repair all depend on a comprehensive and profound understanding of the anatomy; the magnified observation of the tissue structure under wrist arthroscopy at the near microscopic level promotes the development and improvement of anatomical knowledge, and the two complement each other.
(A) Anesthesia, which can be general anesthesia, brachial plexus block anesthesia and local anesthesia at the surgical site, usually brachial plexus block anesthesia is used.
(b) Position, supine position, pneumatic tourniquet placed on the upper third of the affected upper limb, placed on the bedside operating table, shoulder joint abduction 60° to 90°, usually using Whipple traction tower, fixing the upper arm and forearm to the base plate and column of the traction tower, respectively, and adjusting the length and tilt of the bar through the traction finger sleeve, so that the traction force is maintained at 10lb to 15lb and the wrist joint is tilted forward 15° or so. If possible, the “C” shaped arm of the small mobile X-ray machine is placed flat with a sterile clear plastic sleeve, and the center of the ray is aligned with the wrist joint.
(iii) Dissection and examination of the wrist arthroscope
Under anesthesia, tourniquet and traction, the surgical markers are traced, which are more accurate and do not show much displacement during surgery. The radial trochanter, Lister’s tuberosity, ulnar tuberosity and the tip of the ulnar trochanter are marked on the dorsal side of the wrist joint, then the contour lines of the distal end of the ulnar radius are connected and outlined, the bases of the 2, 3 and 4 metacarpals are marked, the extensor tendon and the ulnar carpal extensor tendon are marked, and the distal transverse carpal crest and its midpoint and the radial carpal tendon are marked on the dorsal side of the wrist joint. The commonly used dorsal approach to the radial carpal joint is located between the dorsal extensor tendon sheaths, from which the name is derived. (Figure 3)
Figure 3 Schematic diagram of the commonly used wrist arthroscopic approach
The 3/4 approach, located between the dorsal third and fourth extensor tendon sheaths, i.e., from the common extensor tendon to the radial side of the index finger tendon and the ulnar side of the long thumb extensor tendon. The bony marker is Lister’s node, which has a soft spot on the mid-designated radial line approximately 25 px distal to it, which is this approach. 4/5 approach, located on the ulnar side of the tendon from the common extensor tendon to the tendon of the little finger, and on the radial side of the intrinsic extensor tendon of the little finger. Because of the distal inclination of the radius, this approach is somewhat closer to the 3/4 approach (it cannot be farther than the 3/4 approach), at the soft point on the ulnar side of the fourth extensor tendon sheath. 6R approach, on the radial side of the ulnar carpal extensor tendon (sixth extensor tendon sheath), at the soft point on the ulnar side of the intrinsic extensor tendon of the little finger. 6U approach, on the ulnar side of the ulnar carpal extensor tendon (sixth extensor tendon sheath), dorsal to the ulnar carpal flexor tendon, at the ulnar styloid process distal to its tip. The midcarpal access (radial MCR and ulnar MCU), which are located approximately 25 px distal to the 3/4 and 4/5 accesses, respectively. Each access is marked according to the above position, and the marker line is usually centered on the access point longitudinally and is approximately 0.5 mm long.
Generally, saline is injected into the joint first to expand the wrist joint. To avoid damaging the dorsal branch of the ulnar nerve, the tip of the ulnar styloid process and the ulnar side of the ulnar extensor tendon should be stabbed obliquely in the direction of the proximal radius with a 20-gauge injection needle, and 3 to 5 ml of saline is injected after confirming entry into the joint cavity. At the location of the marked line, using a triangular scalpel, just the skin is incised and there is a mosquito-type vascular clamp to separate the subcutaneous tissue and bluntly break through the joint capsule to enter the joint.
Usually, the 3/4 approach is established first, thinking that this approach is the one that allows observation of most of the intra-articular structures and does not cause damage to the important ligaments of the dorsal wrist. Once the 3/4 approach is established, arthroscopic observation is possible, and the establishment of other approaches is more accurate and simple under the guidance of arthroscopic images and illumination. The 4/5 access and 6R access are generally used for access to instruments during therapeutic procedures. The 6U approach is generally used as an outlet access with an inlet tube attached to the sheath of the arthroscope.
Other approaches include the 1/2 approach, the STT approach (navicular size polygonal joint), the triangular hook approach (TH), and the palmar (VR radial and VU ulnar) approach. 1/2 approach, which is located between the tendon sheath of the short extensor thumb tendon and the tendon sheath of the long and short extensor carpal tendon on the radial side, must be done with care to avoid injury because the radial artery and sensory branches of the radial nerve travel through this area. The STT approach is usually done under the guidance of the arthroscope of the MCR approach and is located 25 px slightly distal to the radius of the MCR approach, on the ulnar side of the thumb extensor tendon, at the junction of the navicular bone and the greater and lesser pollicis, taking care not to damage the radial artery on the radial side of the thumb extensor tendon.The TH approach is located in the gap between the ulnar carpal extensor tendon and the deltoid hook joint, which is generally used as the outlet of the midcarpal joint due to the tight anatomy, and the wrist joint is radially deviated and palpated The VR approach is established through an incision on the surface of the radial carpal flexor tendon on the palmar side, and the radial carpal flexor tendon is retracted ulnarly to break through the base of its tendon sheath into the joint; the VU approach is established through a longitudinal incision at the midpoint of the transverse wrist on the palmar side, and breaks through into the joint immediately ulnarly to the superficial flexor tendon; the palmar approach is established under direct vision, with the aim of not The palmar approach was established under direct vision in order not to damage the vasculature, nerves and tendons on the palmar side. Although these approaches are not routinely used, they are of great value in the management of specific pathological conditions.
A systematic and thorough examination must be performed to ensure that no site is missed. The general order of examination is to start with the radial side then slowly move to the ulnar side. The articular surface and surrounding synovium opposite the radial styloid and navicular bone are first noted for degenerative changes and synovitis. As the arthroscope moves ulnarly, the palmar extrinsic ligament can be seen on the palmar side of the articular cartilage surface of the navicular bone. It begins as the radial navicular head ligament (RSC), followed by the broader long radial lunar ligament (LRL), with a distinct gap between them (Figure 4). Then the soft tissue-like radial navicular lunar ligament (RSL, also known as Testut’s ligament) is visible, smaller often with blood vessels traveling on its surface, and the RSL ligament is the marker of the navicular lunar interosseous ligament (SLIL) and the navicular lunar interosseous joint, and then to the ulnar side is the lunar recess and lunar articular surface of the distal radius.
Figure 4 Wrist arthroscopy 3/4 access view (left side) Figure 5 Probe examination of the TFCC (trampoline test)
Now, note the examination of the triangular fibrocartilage complex (TFCC), which begins with its attachment to the ulnar portion of the radius. The integrity of the TFCC is checked by palpating the central disc with a probe, which is known as the “trampoline test” (Figure 5). If there is no tension in the central disk or if there are cracks on its smooth surface, a tear should be suspected. Both the central and peripheral areas of the TFCC should be examined, as these areas can be damaged, resulting in loss of tension in the TFCC, and the distal ulnar part of the TFCC, the ulnar styloid fossa, is often mistaken for a tear. The next step is to examine the lunotriquetral joint.
Next, the lunotriquetral joint and the ulnar carpal ligament are examined. The lunotriquetral ligament (LTIL) is the distinctive depressed structure between the lunar and triangular bones, and the thickened portion of the ulnar capsule is called the ulnar lunar ligament (UL) and the ulnar triangular ligament (UT), respectively, according to its location. These structures on the ulnar side are best visualized arthroscopically through the 4/5 approach and the 6R approach.
After completing the radial carpal examination, the midcarpal joint must also be examined, which has a significant impact on the diagnosis and treatment of wrist disorders. The first and most obvious sign of the midcarpal joint is the proximal cabochon of the cephalic bone. Turn the arthroscope proximally to observe the radial navicular-lunar interosseous joint and the lunar-triangular interosseous joint, and use a probe to check the stability of these two joints. Advancing the arthroscope along the cephalic bone distal to the radial side, the navicular size polygonal joint can be seen, while advancing the arthroscope along the cephalic bone distal to the ulnar side, the cephalic hook joint can be seen, and attention should be paid to check for early arthritic manifestations.
IV. Treatment techniques of wrist arthroscopy
Since the 1990s, the treatment techniques of wrist arthroscopy have developed greatly, most of them follow the large arthroscopic techniques, or improve on them by using special instruments developed for small joints, and there is a breakthrough in the understanding of acute and chronic diseases of the wrist joint (such as ulnar pain of the wrist), and also more and more wrist surgeries have been carried out, and some obvious clinical treatment results have been achieved.
Under the guidance of arthroscopy, surgical instruments are used to correct the damaged tissue structure in the joint and remove various tissue debris through instruments and irrigation by using the “triangle technique”. For degenerative arthritis of the wrist joint and some stability ligament injuries, the symptoms can be improved by the cleanup procedure.
2.Dorsal carpal cyst excision, 70% of the dorsal carpal cysts come from the ligament between the carpal bones, arthroscopically, the tip of the cyst is shaved off and the origin of the cyst is cleaned up, which can reduce the chance of recurrence, and the arthroscopic surgery incision is small and beautiful.
3. The repositioning and internal fixation of navicular fractures and distal radius fractures, which are the most common and more successful fractures handled arthroscopically in the wrist. The magnified direct view effect of wrist arthroscopy improves the anatomical repositioning of the cartilage surface of intra-articular fractures and does not require incision of the joint capsule and does not damage the limited blood supply to the wrist bone, which is useful for fracture healing and postoperative functional recovery.
4, ligament repair and reconstruction, common ligament injuries in the wrist joint are TFCC, SLIL and LTIL ligament injuries, currently common wrist arthroscopic ligament repair reports are TFCC injury type Ib and Ic, the clinical repair effect is about 70%, more satisfactory. For repair of SLIL and LTIL injuries, open repair was mostly used in the past, and the wrist arthroscope was cleaned up and fixed with kerf pins to keep the carpal bones (navicular bone and lunar bone, lunar bone and triangular bone) in a relatively normal position and wait for the injured ligaments to heal.
5, carpal tunnel syndrome treatment, carpal arthroscopy treatment of carpal tunnel syndrome there are two methods, single-incision and double-incision method, using special instruments, there are careful not to damage the superficial palmar arch and median nerve and its branches, because the carpal tunnel under the pathological state is relatively narrow, also with attention to the intervention of the instrument on the nerve extrusion injury. The immediate and long-term clinical results are not significantly superior compared with the current small incision open surgery.
V. Complications of wrist arthroscopy
Wrist arthroscopy has certain complications, the incidence of which is reported to be about 5.2%. These include general arthroscopic complications, as well as complications related to traction and arm position, the establishment of arthroscopic access, and special repair techniques.
In general, postoperative infections are extremely rare in wrist arthroscopy, and superficial and deep-infection may occur in wrist arthroscopy-assisted percutaneous needle fixation where the needle tail is left outside the skin after the procedure. Injury and fracture of the instruments may also occur during the arthroscopic operation, mainly because the wrist arthroscopic instruments are particularly slender. A good preoperative inspection of the integrity and finish of the instruments and a gentle operation during the operation will help to minimize such complications.
For some cases with skin lesions, such as rheumatoid arthritis, systemic lupus erythematosus or some elderly people, the skin of the fingers is thin and brittle, which is easily damaged. In addition, arthroscopic surgery is long, so we should pay attention to the change of traction weight and tourniquet time to reduce the impact on joint capsule and ligaments (including elbow and shoulder joints) and peripheral nerves.
Complications related to the establishment of arthroscopic access to the wrist are mainly injuries to its surrounding vessels, nerves and tendons. Due to the great variability in the alignment of the cutaneous nerves, the so-called safe area is only relative and the only way to reduce injuries is to operate carefully. When entering the joint, care should be taken not to use sharp sheath cores to prevent damage to the cartilaginous articular surface, and intra-articular instrumentation must be operated within the field of view of the arthroscope. Sharp instruments and materials (e.g., kerf pins) can be dilated and separated by fine vascular forceps before entering to push the nerves and vessels apart and reduce the chance of injury.
With the use of wrist arthroscopy to assist in the repositioning and internal fixation of distal radius fractures, care should be taken to prevent the occurrence of interosseous compartment syndrome in the forearm. The use of gravity irrigation of the joint instead of a pressure pump can reduce the chance of occurrence, in addition to the use of a sterilized elastic bandage wrapped around the forearm to reduce fluid entry into the interosseous compartment. Wrist arthroscopy has made very effective progress in treating some types of injuries in TFCC, although attention should be paid to the damage to the cutaneous nerve from suture knots, and some procedures can be done under direct vision with appropriate skin incision to reduce complications.
Complications of wrist arthroscopy will inevitably occur, but with increased operative experience, anatomical knowledge, the addition of surgical instruments and careful surgical manipulation, the chance of occurrence can be reduced.