Arthroscopy of the Knee Joint: Explained

Arthroscopy of the knee joint is a medical procedure used in both diagnosis and therapy of various injuries or degenerative changes of joints. Arthroscopy is primarily used in orthopedics and trauma surgery. The arthroscope is a variant of the endoscope that is used exclusively in the therapy and diagnosis of pathological joint changes. Decisive for the function of any arthroscope is the basic principle of its construction. Regardless of where the device is used, every arthroscope consists of an optical system of special rod lenses and a small but powerful light source. Furthermore, irrigation devices are often integrated into the arthroscope. Using arthroscopy, it was possible for the first time to perform minimally invasive surgical interventions in the joint area. Diagnostic arthroscopy is of particular importance in surgery and orthopedics because, on the one hand, it can be performed as a stand-alone examination and, on the other hand, it can be used directly as part of peri- and preoperative diagnostics (its use is possible during and before surgery).

Indications (areas of application)

Absolute indications

  • Symptomatic knee injury – arthroscopy should be used primarily after a severe traumatic knee injury. To determine the damage that has occurred to the ligamentous structures, cartilage, and menisci, it is sometimes necessary for arthroscopy to be performed by an experienced surgeon or orthopedic surgeon.
  • Blockage of the knee joint – as a result of trauma, it may not be possible to move the affected knee joint after several weeks of attempts. In addition to identifying the joint structure responsible for the blockage, therapeutic intervention by means of arthroscopy as a whole is also often effective in achieving the goal.

Relative indications

  • Meniscal lesion – if there is a suspicion for the presence of damage to the meniscus, the use of arthroscopy should be considered for both diagnosis and therapy in cases of therapy-resistant pain. However, it should be remembered that meniscal damage does not always have to be persistent (permanent) and conservative therapy may have the same effect as surgical intervention in some cases.
  • Unclear chronic knee joint pain – chronic pain in the knee joint, especially in elderly patients, is usually due to degenerative changes in the knee joint in the context of years of overuse of the joint. However, if there is no clear cause for the occurrence of chronic pain, an arthroscopy should possibly be performed in addition to image diagnosis.
  • Surgical preparation – the precise planning of a surgical intervention on the knee joint requires the use of diagnostic tools. Here, in addition to imaging diagnostics, arthroscopy should also be mentioned. In the meantime, however, arthroscopy is no longer the procedure of choice in surgical planning.

Contraindications

  • Infection – if there is inflammation in the surgical area, arthroscopy cannot be performed under any circumstances.
  • Immunosuppressive therapy – treatment with cortisone or other immunosuppressive drugs should be considered an absolute contraindication to performing arthroscopy. The risk of secondary infection is significantly increased by the use of such substances. If there is a non-drug weakening of the immune system, the arthroscopy may also not normally be performed.
  • Coagulation disorders – the use of anticoagulant substances or the presence of a pathological coagulation disorder should lead the surgeon either to cancel the planned procedure or to stabilize coagulation by additional measures. With the help of blood tests (coagulation status), it is possible to check the blood clotting characteristics and allow the patient to undergo the procedure.

Before surgery

Arthroscopy represents a minimally invasive diagnostic or therapeutic procedure that can be used on an outpatient basis. Due to this, general anesthesia is usually not necessary. Furthermore, food abstinence is also not necessary before the examination.However, it should be noted that the procedure can also be used during a surgical intervention, so that special preoperative measures must of course be carried out here as part of the preparation for surgery.

The surgical procedure

Arthroscopy was considered the absolute gold standard (first-choice procedure) in knee joint diagnostics just a few years ago. The reason for this status was primarily the fact that arthroscopy could be used to visualize the interior of the knee joint with moderate effort. Nowadays, however, the procedure is usually no longer the primary diagnostic procedure used because it is an invasive method and magnetic resonance imaging (MRI) is more expensive but noninvasive. Therefore, the use of MRI, as opposed to arthroscopy, has increased significantly. Despite all this, arthroscopy still enjoys relatively high popularity because it can be performed on an outpatient basis and can be described as having few complications overall. Of crucial importance to the usefulness of arthroscopy is the integrated video camera. In order for it to be used optimally, the surgeon must have excellent vision. It is therefore essential that the positioning and position of the knee joint are adapted to the structures to be examined. The following structures of the knee joint can be visualized and examined with arthroscopy:

  • Meniscus – the presence of tears in both menisci can be checked by arthroscopy and simultaneous palpation (palpation) of the menisci. Although inspection of the menisci is also feasible using noninvasive magnetic resonance imaging, arthroscopy is considered the procedure of choice because therapeutic care of the meniscal lesion (meniscal damage) can be provided immediately after abnormality is detected by arthroscopy.
  • Joint surface – for optimal assessment of the joint surface, it is necessary to use adequate inspection (appraisal) and palpation for assessment in addition to performing arthroscopy. With the help of this combination, it becomes possible to differentiate between both old and fresh lesions (injuries) and to unerringly detect degenerative changes. However, despite the aforementioned possibilities, it is relatively difficult to specify the exact clinical impact of the detected changes. The performance of clinical studies has shown that patients in whom significant degenerative changes in the knee joint were detected, sometimes complained of no symptoms.
  • Ligamentous injuries – ligamentous injuries can also be assessed with the aid of arthroscopy, although it should be noted here that the significance of the diagnostic procedure is primarily dependent on the ligament affected. In particular, the anterior of the two cruciate ligaments is clearly visible during the examination, but the posterior is much more difficult to assess. Unlike the two cruciate ligaments, the collateral ligaments cannot be assessed by arthroscopy because they are extraarticular (outside the knee joint). Furthermore, the stability of the knee joint can be assessed under anesthesia during a surgical procedure.
  • Synovial membrane – this membrane of the joint, which, among other things, serves to nourish the joint and has an important function for stability, is relatively often characterized by an inflammatory process, which can be detected relatively easily with the help of a biopsy during arthroscopy, However, the relevance of the findings produced must be considered low, since the procedure is limited to a few rare pathological processes. However, the usefulness of the procedure can be seen when a completely inconspicuous synovial membrane is detected, as this makes an intra-articular (within the joint) cause highly unlikely.
  • “Free joint bodies” – arthroscopy is used both to find and remove the so-called free joint bodies, which can arise due to joint folds and adhesions in the joint area. The exact significance for the development of pain must be clarified individually for each patient. Existing adhesions make it much more difficult to perform an examination in normal cases. Adhesions can be removed during an arthroscopic examination or by a separate arthroscopy.
  • Foreign bodies – the presence of foreign bodies in the knee joint may be the result of trauma (injury) or a result of surgery.A foreign body can not only lead to pain and restricted movement, the likelihood of inflammatory infiltration of the joint is massively increased.

After surgery

Since the procedure can usually be used on an outpatient basis, only a short period of rest is required after the procedure is performed before the knee joint can be loaded again without concern. A follow-up examination is performed one week after the procedure. If necessary, it may be necessary to relieve the affected knee joint by using forearm supports while walking.

Possible complications

Compared with invasive therapeutic procedures, arthroscopy can be considered to have few complications. Although it is a minimally invasive procedure, serious complications can still occur, although it should be noted that this is highly rare.

  • Embolism – as a result of thrombus (clot) formation, there is a possibility of migration of the thrombus, so that in the worst case, as a result of blockage of a heart supply vessel, a myocardial infarction (heart attack) can occur. This can also lead to death. However, due to the short lying time after the procedure is performed, the risk is very low.
  • Infection – in the course of arthroscopy, the development of an inflammatory process is possible, but relatively rare. The risk of infection is present even with near-optimal hospital hygiene. The risk of infection is additionally dependent on the duration of lying before the performance of arthroscopy.
  • Vascular lesions – in the area of the knee joint, the supplying vessels are relatively superficial and unprotected, so that a handling error in the use of an arthroscope can lead to damage to nerve and vascular structures. Particular care must be taken to avoid damage to the popliteal artery, especially in the knee region, as this usually forces the surgeon to perform an amputation. The fibular nerve and the saphenous nerve can also be damaged by the procedure, so that far-reaching consequential damage can occur.

Further notes

  • International expert panel – Rapid Recommendations section in the journal BMJ: Arthroscopic debridement (“knee joint toilet”) of the knee joint should no longer be part of the therapy in patients.
    • With degenerative knee joint osteoarthritis.
    • With meniscus tear
    • Purely mechanical symptoms
    • Absent or minimal signs of osteoarthritis on imaging
    • Sudden onset of symptoms not due to trauma
  • Billing note in the care of SHI-insured patients with gonarthrosis: as of spring 2016, arthroscopies may only be billed for patients with trauma, acute joint blockages and meniscus-related indications in which the existing gonarthrosis is only to be considered a concomitant disease. The method evaluation concluded that the procedures studied have no evidence of benefit compared to sham surgery or no treatment (IQWIG).