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Principles of Arthroscopy

Principles of Arthroscopy

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  • Arthroscopy is a minimally invasive surgical procedure on a joint in which an examination and sometimes treatment of damage is performed using an arthroscope, an endoscope introduced into the joint via small incisions
  • It was introduced by Prof Kenji Takaji in Tokyoin 1919.
  • Since its introduction in the past three decades, arthroscopy has changed theorthopaedic surgeon's approach to the diagnosis and treatment of joint pathologies.
  • Low morbidity, with high degree of clinical
  • accuracy has encouraged the use of arthroscopy to assist in diagnostic, therapeutic and prognostic purposes.
  • Arthroscopic procedures should serve as adjuncts to and not as replacements for thorough clinical evaluation; arthroscopy is not a substitute for clinical skills.
  • Improvements in arthroscopy includimg advancement in the instruments has led to use of arthroscopy in advanced surgery including all joints of the body including spine surgery.


  • Decreased morbidity
  • Better cosmesis
  • Decreased metabolic response
  • Improved diagnosis
  • Reduced hospital stay and cost
  • Decreased complication rate


  • Technical requires patience
  • Cost of instrumentsIndications
  • Diagnostic
  • For preoperative evaluation and confirmation of joint disease
  • For medicolegal reasons


  • Increased risk of sepsis
  • Should not take the place of history, physical examination and non invasive investigations
  • Partial or complete ankylosis
  • In minimally deranged joint that could be managed conservatively
  • Anaesthesia depends on which joint is to be scoped
  • Local, Spinal, General anaesthesia
  • Informed consent obtained


  • ARTHROSCOPE: Three basic optical systems have been used in rigid arthroscopes:

  1. (the classic thin lens system,
  2. the rod-lens system designed by Professor Hopkins of Redding, England
  3. the graded index (GRIN) lens system.

  • Certain features most important are the:

    •  Diameter: between 1-7mm
    • Angle of inclination that is the angle between axis of the arthroscope and line perpendicular to the surface of the lens and it’s usually between 0-120. 25 and 30 degree scopes are commonly used and 70 and 90 for viewing corners
    • Field of view: refers to viewing angle encompassed by the lens and varies according to scope. 1.9mm scope has 65” 2.7mm has 90” 40mm has 115”
    • Fiberoptic technology, the use of magnifying lenses, and digital monitors have allowed advancements in arthroscope design.
  • Newer arthroscopes offer an increased field of view with smaller scope diameters, better depth of field with improved optics, and better flow through the sheath.
  • Light source
  • TV camera

  • Other instruments

    • Probe: this is regarded as an extension of the arthroscopist’s finger. Its essential both for diagnostic and therapeutic purposes. Essential for palpating intraarticular structures and for planning approach.
    • Scissors: usually 3-4mm in diameter. The jaws may be straight or hooked.
    • Basket (punch) biopsy forceps: useful in trimming peripheral rim of the meniscus
    • Grasping forceps: to retrieve materials from the joint or to place meniscal flaps under tension while cutting.

grasping forceps

    • Knife blades: most blades currently in use are single use disposable. Usually they come with a sheath which is only released when inside the joint and not in the scope.
    • Motorised shaving system: 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. The window of the inner sheath functions as a two-edged, cylindrical blade that spins within the outer hollow tube.
    • Most systems use a foot pedal to control the motor and allow both clockwise and counterclockwise rotation
motorised shaver system
    • Implants: suture anchor, meniscal repair device, device for tendon and ligament fixation
    • Laser and radiofrequency instruments
    • Fluid for distension
    • Tourniquet


  • Proficiency in arthroscopic techniques requires a great deal of patience andpersistence.
  • The instruments are small and delicate and must be maneuvered in tight, confined spaces.
  • Everything is magnified, and because the arthroscope is monocular and twodimensional, depth perception is a matter of experience rather than observation.

  • Triangulation:

    • Triangulation involves the use of one or more instruments inserted through separate portals and brought into the optical field of the a rthroscope, the tip of the instrument and thearthroscope forming the apex of a triangle.
    • The principle of triangulation is the basis for operative arthroscopy.
    • Triangulation separates the arthroscope from the operating instrument, allowing the viewing arthroscope to be enlarged and increasing the field of view.
  • The angle of inclination can be varied to allow improved visual access to more areas of the joint.
  • Separation of the instruments from the arthroscope improves depth perception and permits independent movement of the arthroscope and the surgical instrument, which is essential for operative arthroscopy.
  • A major setback of triangulation is the necessity of mastering the psychomotor skills to bring two or more objects together in a confined space while using monocular vision.
  • Diagnostic proficiency in simple triangulation with a probe is the critical skill, and once this is mastered, additional skills may be developed.
  • Triangulation of more than one instrument into the optical field of the arthroscope is occasionally required.
  • If it is available, a straight-ahead lens (0- degree) arthroscope makes the learning of triangulation techniques easier. The more angled the fore-lens of the arthroscope, the more difficult the orientation and triangulation procedures.
  • Thorough recognition of the intraarticular anatomy (e.g., recognizing the intercondylar notch and the anterior cruciate ligament or dividing the menisci into thirds and directing the instruments toward that known structure) increases triangulation skills.
  • To begin triangulation, the arthroscope should be at a distance from the area to be probed to give a wide field of visio.
  • When the instrument is located, the scope and the instrument are advanced together toward the intended area, reducing the field of vision while increasing the magnification.
  • A mistake commonly made by beginning arthroscopists is placing the scope too close to objects, thus losing the larger field of vision necessary to maintain constant visual orientation.


  • Commonly positioned supine on table for knee arthroscopy with the knee at 90” and tourniquet applied proximally.
  • Portal points should be marked preoperatively. The standard portal points are the
  • Anterolateral
  • Anteromedial
  • superolateral
  • Optional portals are the posterolateral, posteromedial, proximal mid patella medial and lateral, acessory far medial and lateral portals, central transpatella tendon portal.

marked knee

The knee should be divided routinely into the following compartments for arthroscopic examination:

  1. Suprapatellar pouch and patellofemoral joint
  2. Medial gutter
  3. Medial compartment
  4. Intercondylar notch
  5. Posteromedial compartment
  6. Lateral compartment
  7. Lateral gutter and posterolateral compartment


  • Damage to intraarticular structures
  • Damage to extraarticular structures
  • Hemarthroses
  • Thromboprophylaxis
  • Infection
  • Synovial herniation/fistula
  • Instrument breakage

Follow up

  • Usually patients who have had their joint scoped return to sedentary life immediately and to active function in about 2weeks.
  • They are usually discharged immediate post op or maximum 48hrs post operative.

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