A Ten Year Experience with Minimally Invasive Partial Knee Replacement

Associate Professor Michael Neil, a member of Invivo's Medical Advisory Panel discusses partial knee replacement and the latest technology assisting patients.

The surgical treatment of patients with single compartment bone on bone arthritis of the knee remains a challenging problem, particularly in the younger, more active age group. In days gone by, patients who underwent an open meniscectomy often developed bone on bone arthritis 20 years later. These patients are becoming less frequent as there was a move towards arthroscopic surgery about 15-20 years ago. Nevertheless, with patients living longer and with increasing participation in impact sports at all ages, there are still large numbers of patients who present with this challenging problem.

A young, active patient having a total knee replacement has a high chance of needing revision. Further, the results of this procedure in uni-compartmental arthritis are not all that brilliant - it is a case of too much surgery for a limited problem.

To overcome this tibial "wedge osteotomy" was devised. While conservative in that there is no implant in the knee, there is a high complication rate, a high failure rate (50% in the long term) and recovery time is slow.

15 years ago an American, Dr John Repicci who trained in both dentistry and orthopaedic surgery developed partial knee replacement carried out on an outpatient basis. Some ten years ago I trained with Dr. Repicci and then set up a day surgery "Uni knee programme" which continues today. With three other colleagues, we designed our own version of the "Repicci" partial knee, which has now been sold to a large multinational device company, for distribution primarily in the Asia Pacific region. It is quite rare for an orthopaedic implant to be fully designed and manufactured in Australia for distribution overseas. I now have experience with over 1000 cases, using in great part the designed modified device. A recent clinical review showed a patient satisfaction rate of over 95%. Strict criteria for the survey were used, for example, if a patient cannot walk because of a painful foot, he will score poorly, even though the implant is working well.

Surgery

Most patients undergo their surgery in the day surgery unit and are discharged that day or the next morning. The procedure is carried out under direct visualisation using a relatively small incision. Great attention is given to analgesia, both throughout the procedure and post operatively. Local analgesia through a catheter infuses into the joint for a few days and NSAID's play a major role.

Recovery

Walking aids are discarded by day seven. Most patients are back at work in two weeks. Non impact sports can be resumed at six weeks with full recovery taking one year.

Revision

Our implant has a 10 year life expectancy, but in practice few fail - most revisions take place because of progression of arthritis.

Informed Consent

It is important that the patient be aware that undue delay can lead to more extensive arthritis, which would preclude the use of a partial replacement. Also, patients have a diagnostic arthroscopy prior to implantation, to be sure the knee is suitable for partial knee replacement. They understand that we may not proceed if the knee is not suitable.

The most serious complications of surgery are infection (which is quite rare because of minimal exposure), fracture, nerve and vessel injury (loss of the post tibial nerve is a major neurological problem), early wear and tear with loosening, and lastly failure, persistent medial tibial pain.

As John Repicci has taught us, partial knee replacement is like having a filling for one bad tooth. Who would have all their teeth out and a denture for a single bad tooth? So why would you have a total knee replacement for a single bad compartment in your knee?

More information is available at www.hipandkneesurgery.net

Michael J Neil
MB BS(UNSW), FRCSEd(Orth), FRACS(Orth), FAOrthA
Director St Vincent's Bone & Joint, Department of Orthopaedic Surgery, St Vincent's Clinic, SYDNEY.
Conjoint Associate Professor of Orthopaedic Surgery, University of New South Wales, SYDNEY.
Invivo Medical Advisor

REFERENCES

1. Ahlback S. Osteoarthrosis of the knee: A radiographic investigation. Acta Radiol. (Stockh). 1968; 277:7-72.
2. Dearborn J.T.,Eakin C.L.,Skinner H.B. Medial compartment arthrosis of the knee. Amer Jour Orthop. Jan 1996;18-24.
3. Marmor L. Unicompartmental knee arthroplasty: ten to 13 year follow up study. Clin Orthop. 226: 14, 1988.
4. Barnes C.L., Scott R.D. Unicompartmental knee arthroplasty. AAOS Instructional course lectures Vol 42,Ch.29 :309-313. 1993.
5. Scott R.D., Santore R.F. Unicondylar unicompartmental replacement for osteoarthritis of the knee. J. Bone and Joint Surg., 63-A:536-544, April 1991.
6. Fu Freddie H., Browner Bruce D. Management of Osteoarthritis of the Knee: An international consensus. Monograph series 25, American Academy of orthopaedic Surgeons. Chapter 8, p67-80.
7. Repicci JA, Eberle RW: Minimally invasive surgical technique for unicondylar knee arthroplasty. J. South Orthop Assoc 1999; 8:20-27.
8. Repicci JA, Hartman JF: Minimally invasive unicondylar knee arthroplasty for the treatment of Unicompartmental osteoarthritis: An outpatient arthritic bypass procedure. Orthop Clin North Am. In press.
9. Australian Orthopaedic Association National Joint Replacement Registry Annual Report 2007.