General Principles of Arthroscopy

Probe

The probe is perhaps the most used and important diagnostic instrument after the arthroscope. The probe has become known over the years as “the extension of the arthroscopist’s finger.” It is used in both diagnostic and operative arthroscopy, and is the safest instrument that one can use when learning triangulation techniques ( Fig. 49.4 ). The probe is essential for palpating intraarticular structures and planning the approach to a surgical procedure. A tactile sensation regarding what is normal and what is abnormal soon develops. It is better to “see and feel” rather than to “see” alone. The probe can be used to feel the consistency of a structure, such as the articular cartilage; to determine the depth of chondromalacic areas; to identify and palpate loose structures within the joint, such as tears of the menisci; to maneuver loose bodies into more accessible grasping positions; to palpate the anterior cruciate ligament (ACL) and determine the tension in the ligamentous and synovial structures within the joint; to retract structures within the joint for exposure; to elevate a meniscus so that its undersurface can be viewed; and to probe the fossae and recesses, such as the popliteal hiatus within the joint. Most probes are right angled with a tip size of 3 to 4 mm, and this known size of the hook can be used to measure the size of intraarticular lesions. The arthroscope magnifies, and the closer the arthroscope, the greater the magnification. Care should be taken in using the tip of the probe; much of the palpation with the probe within the joint is actually done with the elbow of the probe rather than the tip or toe of the instrument.

Scissors

Arthroscopic scissors are 3 to 4 mm in diameter and are available in both small and large sizes. The jaws of the scissors may be straight or hooked ( Fig. 49.5 ). Hooked scissors are preferred because the configuration of the jaws tends to hook the tissue and pull it between the cutting edges of the scissors, rather than pushing the material away from the jaws, which can occur with straight scissors. Optional accessory scissors designs include right- and left-curved scissors and angled cutting scissors. The difference between these two designs is based on the location of the angulation. The shank of the curved scissors is gently curved to accommodate right and left positioning, whereas the angled scissors, usually with a rotating type of jaw mechanism, actually cut at an angle to the shaft of the scissors. These accessory designs are useful for detaching difficult-to-reach meniscal fragments.

Basket Forceps

The basket or punch biopsy forceps is one of the most commonly used operative arthroscopic instruments (see Fig. 49.5 ). The standard basket forceps has an open base that permits each punch or bite of tissue to drop free within the joint and does not require the instrument to be removed from the joint and cleaned with each bite. Small fragments of tissue that drop free within the joint through the open-floor punch or basket forceps can be irrigated out or subsequently removed from the joint by suction. This instrument is available in 3- to 5-mm sizes with a straight or curved shaft. It is useful for trimming the peripheral rim of the meniscus or can be used instead of scissors to cut across meniscal or other tissue. Wide, low-profile baskets are excellent for meniscal work. The configuration of the jaws of the basket forceps may be straight or hooked; again, the hooked configuration is preferred. Baskets are available in an assortment of angles, including 30, 45, and 90 degrees, which are especially useful for trimming the anterior portions of the meniscus. They also are available in 15-degree down-biting and up-biting curves to make it easier to get around the femoral condyle during resection of the posterior meniscal horn. As with other arthroscopic instruments, the proper technique is to make small bites to avoid excessive pressure on the joints and pins of the instrument and to prevent frequent breakage.

Hinged, jawed suction punches are available to cleanly bite small bits of meniscus or other small tissues and suction them from the joint through a channel in the shaft of the punch. This prevents fragments of tissue from floating in the joint, blocking vision, and ensures removal of all free fragments from the joint. This instrument, however, often is too large to reach tight posterior areas.

Grasping Forceps

Grasping forceps (see Fig. 49.5 ) are useful for retrieving material from the joint, such as loose bodies or synovium, or for placing meniscal flaps and other tissues under tension while cutting with a second instrument. Most grasping forceps have some type of ratchet closure on the handle to secure the tissue within the jaws. The jaws of the grasping forceps may be of single- or double-action design and may have regular serrated interdigitating teeth or one or two sharp teeth to better secure the grasped tissue. The double-action grasping forceps, of which both jaws open, are especially preferred for securing an osteocartilaginous loose body because the single-action types frequently allow it to slip from between the jaws.

Knife Blades

Most arthroscopic knives currently used are disposable, single-use instruments. A variety of disposable blade designs are available: hooked or retrograde blades; regular down-cutting blades, both straight and curved; and Smillie-type end-cutting blades. Magnetic properties are also helpful in retrieving the blade if it is inadvertently broken inside the joint. These blades should be inserted through cannula sheaths or encased within a retractable sheath mechanism so that the cutting portion of the blade is only exposed when it enters the field of arthroscopic vision and not as it enters through the entry portal.

Motorized Shaving Systems

The motorized shaving systems are all basically of similar design, consisting of an outer, hollow sheath and an inner, hollow rotating cannula with corresponding windows ( Fig. 49.6 ). The window of the inner sheath functions as a two-edged, cylindrical blade that spins within the outer hollow tube. Suction through the cylinder brings the fragments of soft tissue into the window, and as the blade rotates, the fragments are amputated, sucked to the outside, and collected in a suction trap. Numerous cutting tips have been developed for specific situations and functions. The diameter of the cutting tip is usually 3 to 5.5 mm, and many of the tips have variable sizes to allow access to smaller or tighter joints. Special blades have been designed for meniscal cutting or trimming, synovial resection, and shaving of articular cartilage. Special burrs and abraders have been designed for arthroscopic acromioplasty and ACL reconstructions. Most systems use a foot pedal to control the motor and allow for variable speed and direction. Reversing the rotation of the cutting blade intermittently often improves cutting efficiency and minimizes clogging with debris. Motorized shavers have been developed for small joints with a 2-mm shaver and burr.

Finally, the cutting tip should always be positioned within the visual field, and the position of the window should be located before activating the rotary motion of the blade.

Electrosurgical, Laser, and Radiofrequency Instruments

Electrocautery has been used as an arthroscopic tool for cutting and hemostasis most often after arthroscopic synovectomy and subacromial decompression. It also has been used for both cutting and hemostasis in lateral retinacular release for malalignment of the patella.

At a much lower cost, radiofrequency systems have been reported to produce heat energy similar to that of lasers which have fallen out of favor. The two types available are monopolar and bipolar. Monopolar devices use a grounding pad and draw energy through the body; with bipolar devices, energy is transferred between electrodes at the site of treatment. Current controversies include the depth of tissue penetration, the amount of cell death, and the ability of the devices to monitor and to control temperature. Reported complications of radiofrequency meniscal ablation include articular cartilage damage, osteonecrosis, and tissue damage caused by the irrigant.

Implants

A variety of implants, both metal and biodegradable, have been developed for use in arthroscopic procedures, including suture anchors, meniscal repair devices, and devices for tendon and ligament fixation and articular cartilage repair.

Suture anchors are used to attach ligaments and tendons to bone without the need for creating a bony tunnel for the passage of sutures. Instead, sutures are passed through an eyelet on the suture anchor, which is inserted into the bone. According to Barber and Richards, desirable characteristics of a suture anchor are that it must fix the suture to the bone, not pull out of the bone, permit an easy surgical technique (the ability to tie an arthroscopic slip knot), and not cause long-term problems; other desirable features include biocompatibility, adequate strength, easy insertion, and the ability to allow early rehabilitation. Suture anchors are used most often for arthroscopic procedures around the shoulder. Small-diameter all-suture anchors, polyetheretherketone (PEEK) biocomposite or metal anchors can be used; these have less potential for producing osteolytic reactions that have been associated with bioabsorbable implants.

Meniscal repair devices, of varying designs and materials, allow an all-inside meniscal repair without the need for arthroscopic knot-tying, accessory portals, or incisions. The first-generation meniscal repair devices were solid flexible devices placed across the tear to hold the meniscal fragments in place. Today’s fourth-generation devices are low profile, have a suture tension construct, and provide much greater fixation strength. The techniques for use of specific meniscal repair devices are discussed in Chapter 45, Chapter 51 .

Depending on the graft chosen, cruciate ligament fixation devices can be used for bone-to-bone fixation or for soft tissue-to-bone fixation. They may be made from either biodegradable or nonbiodegradable materials.

Miscellaneous Equipment

A variety of sheaths and trocars are required for arthroscopic surgery, and they must accommodate the arthroscope and accessory equipment being used. When possible, sharp instruments should be placed through sheaths to protect the soft tissues of the skin portals. Motorized instruments can be used with or without a sheath. The initial perforation through the capsular and synovial tissue may be made with a No. 11 blade and blunt trocar or with a sharp trocar carefully passed through the appropriate instrument sheath. Some systems allow cannulas to be interchanged for inflow, arthroscope, and motorized shaver systems. Disposable plastic cannulas with sealed ends reduce fluid extravasation.

As arthroscopic surgery procedures have advanced to cater for more joints, additional instruments have been developed. “Switching sticks” are simple rods placed through the cannula to maintain the portal while the cannula is exchanged. For a larger operating cannula, a dilator is used before exchange. The Wissinger rod was designed to assist in establishing a portal on the opposite side of a joint from a previously established portal. Traction devices have been developed for use in the shoulder, elbow, and ankle for better exposure (see Chapter 50, Chapter 52 ). There has also been an explosion of procedure-specific instruments, many of which are described in the pertinent operative sections in Chapter 50, Chapter 51, Chapter 52 .