Arthroscopic surgery is a minimally invasive surgical technique where surgical procedures are performed through two to three 3-MM slit incisions (portals) in the skin.
A surgical telescope (arthroscopic) is placed through these portals into the underlying joint and through additional portals specifically designed instruments can be inserted to perform the procedure. The joint is distended with a saline solution usually through a pump to allow clear unobstructed viewing of the joint.
A fiber optic cable connects a small camera on the arthroscope to the viewing monitor and the surgeon manipulates the instruments while viewing the monitor. This is usually done at an ambulatory surgery center as an outpatient under general or local anesthesia. Regional nerve blocks can accompany anesthesia to further control postoperative pain.
Arthroscopic methods have progressively evolved during the last three decades making most open procedures obsolete. Barring most extra-articular (outside of the joint) restructions and joint replacement almost all surgical procedures are done in a fully arthroscopic manner.
Almost all ailments of the knee can be treated arthroscopically. What historically took months for recovery now takes days or weeks with arthroscopic approaches. Typically two portals are used although additional portals can be used without affecting recovery.
The most common reason for using arthroscopic surgery in the knee is a torn meniscus (cartilages) in the knee, one medially (inner side) and one laterally (outer side). The meniscus is a very important structure transmitting 50% of the joint load medially and 70% laterally. It iscomprised of fibrocartilage and has a very poor blood supply, its nutrition being received from the joint fluid. Because of this poor blood supply, tears of the meniscus rarely heal on their own and almost always require surgical treatments. The meniscus can tear from a variety of reasons. In the first few decades of life this usually requires a significant trauma to the knee (i.e., sports injury).
Past the age of 40 even simple activities such as rising from a chair or stepping awkwardly off a curb can cause a tear. Unfortunately, from a practical standpoint, there is nothing one can do to prevent a meniscus from tearing. Once torn, the can usually cause pain in the back part of the knee. This is occasionally associated with swelling and the pain can be worsened with flexion of the knee.
The symptoms can sometimes be intermittent or seen only with high levels of activity. The diagnosis can be made with a clinical examination and if necessary confirmed with an MRI scan, which is approximately 95% accurate for detecting meniscal tears. Because the meniscus does not heal, the damaged portion needs to be removed. The smaller the tear present the less amount of tissue needs to be removed and conversely, with a larger tear, more meniscal tissue must be removed. Obviously, because it is an important transmitter of load in the joint, it is advantageous to treat a meniscus tear when it is small so that less tissue has to be removed.
Certain tears that occur where the meniscus connects to the joint and can be repaired by sewing. These tears usually involve the entire meniscus and occur in younger individuals. Removal of the entire meniscus in these large tears predisposes one to significant arthritis and therefore preservation of the meniscus is extremely important. Because the meniscus has no real blood supply we rely on the blood supply of the neighboring tissues to grow into the tear and heal it. Accordingly, the tear must be less than 5mm or closer to the joint lining for any meniscal tear to predictably heal. Special instrumentation is required for meniscal suturing.
Large needles with sutures are passed up through the joints and exit the skin on the side of the meniscus that is being repaired in order to retrieve the sutures. The incision is necessary to prevent injury to the saphenous nerve, which gives sensation to the inner leg and ankle. For lateral suturing an incision is also used because there is a risk of injury to the peroneal nerve, which allows you to raise your foot up and down in the popliteal artery, which is the main artery behind the knee. For all adolescents and young adults I feel that all attempts should be made to repair the meniscus rather than removing it and if possible prevent future arthritis.
The most mechanically sound suture configuration is a vertical suture that is placed by hand. Usually 6 to 16 sutures are placed depending on the tear size. Commercial devices have been developed, but none have achieved the same degree of mechanical strength as a suture placed by hand. All of them, in fact, have been shown to be inferior to suturing by hand. Several of these devices are associated with joint damage. Unfortunately, great skill and patience is required to successfully sew a meniscus and for this reason it is surely preferred. My policy is to sew all tears that meet appropriate requirements. If a meniscal tear doesn’t heal after suturing, the torn portion can be removed at a later date if it causes symptoms.
Orthopedic Corner | Leon Mead MD Orthopedic Doctor | 730 Goodlette Road North, Suite 201 Naples Florida 34102 | Phone: (239) 262-1119