ATOK (Arthroscopic Trans-Osseous Knotless) Rotator Cuff Repair
Dr. Michael Sandow
Wakefield Orthopaedic Clinic
The gold standard for repair of disrupted rotator cuff has been the trans-osseous repair. This has stood the test of time and whle arthroscopic repairs have attempted to improve on the execution and means of repair, the open trans-osseous repair has remained the benchmark.
The holy grail of rotator cuff repair however is the ability to perform the trans-osseous repair with its attendant mechanical advantages but by an arthroscopic technique – and without the need to tie knots.
There is a plethora of techniques described as “trans-osseous equivalent” which aim to use anchors either in a double or single row approach and then add a further over the top type repair to provide a downward pressure on the cuff itself to hold the lateral margin down.
While the elegance of inserting anchors into the humeral head and then tying the tendon down onto them has been promoted heavily, and there are multiple studies looking at pull out strengths in cadaver bones and similar, there are a number of mechanical compromises which are required. The art of tying knots is somewhat of a challenge and consequently there are now techniques which avoid insertion of knots to achieve the repair to the great tuberosity. While previously the tendon was pulled into a cancellous bed, the tendon is now laid onto a bare area of bone and the area of bone is now no longer even scarified as various studies have shown that this is sufficient for poorly vascular tendon to heal onto sclerotic great tuberosity bone.
The insertion of a tendon into a cancellous bed trench such as used in the standard trans-osseous repair may have some advantage but these have not been proven. The rotator cuff that is tied down onto the greater tuberosity surface with anchors and knots has a number of possible compromises. Any give of the knot or the anchor will allow for gapping of apposition of the greater tuberosity to the tendon. This in itself may interfere with healing and various reports have suggested an incomplete healing rate with arthroscopic repairs.
At Wakefield Orthopaedic Clinic we have been using a trans-osseous open repair technique but have now developed a means of achieving the trans-osseous repair but through an arthroscopic technique and without the requirement to tie knots. This involves inserting the sutures into the torn end of the rotator cuff and then preparing a trench and then trans-osseously passing the sutures using a specially designed jig. An anchor is inserted in retrograde fashion to lock the sutures onto the lateral cortex.
At this stage we are using the Smith & Nephew Footprint anchor in an off licence technique and initial series show good cuff apposition with follow up MRI scans showing the durable position of the anchor and correct positioning of the tendon.
We also have an improved and patented anchor which is still under development. The ATOK technique we believe will prove to be the holy grail of rotator cuff repairs. It has the advantages of trans-osseous repair, it avoids knots in the subacromial space and knot tying generally and is adjustable with a low mechanical failure rate – and all this with the reduced morbidity of the arthroscopic approach. Further studies are now underway to validate the apparent satisfactory initial outcome. Preliminary results have been very encouraging.
For more details, contact:
Business Manager, Wakefield Orthopaedic Clinic
Document created: 26 August 2010