Technological Influences on Knee & Shoulder Surgery
By Dr Michael Ledger, Orthopaedic Surgeon, Mercy Hospital. Tel 0412 785 234
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echnological developments continue to refine and improve orthopaedic surgery, especially for shoulder and knee procedures. Many shoulder operations that previously required open exposures can now be performed arthroscopically thanks to improved instrumentation, better implants designed for arthroscopic work, and surgeons who have developed the clinical usefulness of new arthroscopic techniques. significant muscle atrophy are difficult to satisfactorily repair, either arthroscopically or using standard open techniques.
Knee surgery has a similar story. The improved accuracy and better results that computer navigation has brought to total knee replacement (TKR), have more recently been extended to uni-compartmental knee replacement and high tibial osteotomy.
Navigation systems and knee surgery
Computer navigation systems give the surgeon real-time measures of accuracy that allows for precise component implantation and improved lower limb alignment. The aim is to enhance the longevity of a joint replacement and reduce the need for revision surgery.
Arthroscopic shoulder stabilisation
Shoulder dislocation is most common in younger active patients, often during sport. Typically, the ligaments and labrum at the front of the shoulder joint tear as the shoulder dislocates. Thereafter, contact athletes and younger active people may develop ongoing shoulder instability, and will require surgical stabilisation.
n A . Arthroscopic view of rotator cuff tear.
The keyhole arthroscopic technique aims to restore the soft tissue “bumper” at the front of the glenoid, to prevent the shoulder from dislocating forwards again. Small bone anchors are inserted into the rim of the glenoid, and the torn labrum and capsule are brought back to their normal position with sutures, so they can heal and attach to the bone. The capsule at the front of the shoulder (in the interval between biceps and subscapularis) can also be tightened arthroscopically if necessary, without overly restricting external rotation.
The arthroscope has also improved our understanding and treatment of other associated but less commonly seen injuries. For example, a large anterior labral tear can extend circumferentially to involve the posterior labrum – this can be repaired with the same techniques. Or the attachment of the long head of biceps may be torn (a SLAP lesion) or inferior glenohumeral ligament tears visualised and repaired.
Patient selection: Arthroscopic stabilisation is suitable for most patients. Pre-operative imaging studies (x-ray and MRI) will determine if there is a significant bone defect at the anterior glenoid margin (Bankart lesion) or at the back of the humeral head (Hill-Sachs lesion). If this is the case, an open stabilisation procedure may be necessary.
n B. Anchors in place and sutures ready for tying knots.
Additionally, the trackers are active throughout the surgery, providing the surgeon with intra-operative feedback regarding the accuracy of bone cuts and overall alignment and balance, prior to final implantation of the prosthesis.
This translates into maximal consistency and accuracy for each patient.
Newer systems have been developed that are easier to use, add no extra time to the procedure, and have distinct advantages for the patient. Navigation avoids the use of intra-medullary jigs that can cause problems associated with systemic fat emboli.2 The “lighter” version of navigation does not require navigation pins to be inserted separately; rather, the navigation trackers are mounted on new specialised TKR instrumentation.
n C . Final tendon repair using the arthroscope.
Arthroscopic rotator cuff repair
This relatively new technique is considered advantageous due to small skin incisions and less extensive damage to extra-articular structures (than open repair). Other advantages include reduced blood loss and less muscle damage, resulting in less postoperative pain.1 The technique may also reduce post-operative shoulder stiffness, sometimes seen after rotator cuff repair.
Improvements in instrumentation and expertise over time now means we are able to arthroscopically repair partial thickness tears, full thickness tears, subscapularis tendon tears, and even larger cuff tears involving more than one tendon. At the same time, if necessary, long head of biceps pathology, subacromial spurs and impingement, and acromioclavicular joint degenerative changes can be addressed. Patient selection: All patients with a symptomatic rotator cuff tear be considered. Very large chronic retracted tears associated with
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Minimally invasive wireless “pointers” and “trackers” send data about knee movement (kinematics) to the computer. This information is translated into real-time images that provide the surgeon with a comprehensive understanding of the knee mechanics before any bone is cut.
Applying the same navigational accuracy to medial unicompartmental knee replacement and high tibial osteotomy also should benefit both of these techniques. n
Refs
1. Tsuyoshi Shinoda et al. A comparative study of surgical invasion in arthroscopic and open rotator cuff repair. Journal of Shoulder and Elbow Surgery 2009;18, 4 : 596-599
2. J. S. Church et al. Embolic phenomena during computer-assisted and conventional total knee replacement. J Bone Joint Surg Br, Apr 2007; 89-B: 481485.
Mercy Hospital Mount Lawley, Thirlmere Road, Mount Lawley 6050 • Tel 08 9370 9222 • Fax 08 9370 9488 • Email: hospital@mercycare.com.au
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